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Annotation of micropolis/src/tk/tktcp.c, revision 1.1

1.1     ! root        1: /* tkTCP.c --
        !             2:  *
        !             3:  *     This file provides basic capabilities to establish a server,
        !             4:  * attached to a TCP/IP port, that attaches to a Tcl interpreter.
        !             5:  * Such servers provide a remote-procedure-call mechanism for Tcl
        !             6:  * without needing to resort to Tk's X-window-based complexities, and
        !             7:  * also allow access to services that are not bound to any particular
        !             8:  * display.
        !             9:  */
        !            10: 
        !            11: static char RCSid [] =
        !            12:   "$Header: /cluster21/kennykb/src/tclTCP.1.0beta/RCS/tclTCP.c,v 1.7 1992/05/05 18:31:13 kennykb Exp kennykb $";
        !            13: /* $Source: /cluster21/kennykb/src/tclTCP.1.0beta/RCS/tclTCP.c,v $
        !            14:  * $Log: tclTCP.c,v $
        !            15:  * Revision 1.7  1992/05/05  18:31:13  kennykb
        !            16:  * Changed the flow through the `delete server' code to make it work even
        !            17:  * if a server is deleted while a client is active.
        !            18:  * The change avoids aborts at termination time if the server delete code
        !            19:  * is reached before the application exits.
        !            20:  *
        !            21:  * Revision 1.6  1992/03/04  20:04:00  kennykb
        !            22:  * Modified source code to use the Tcl configurator and corresponding include
        !            23:  * files.
        !            24:  *
        !            25:  * Revision 1.5  1992/02/25  15:21:30  kennykb
        !            26:  * Modifications to quiet warnings from gcc
        !            27:  * ,
        !            28:  *
        !            29:  * Revision 1.4  1992/02/24  19:30:30  kennykb
        !            30:  * Merged branches (a) updated tcpTrustedHost and (b) broken-out event mgr.
        !            31:  *
        !            32:  * Revision 1.3  1992/02/20  16:22:53  kennykb
        !            33:  * Event management code removed and broken out into a separate file,
        !            34:  * simpleEvent.c
        !            35:  *
        !            36:  * Revision 1.2.1.1  1992/02/24  19:12:30  kennykb
        !            37:  * Rewrote tcpTrustedHost to be more forgiving of unusual configurations.
        !            38:  * It now looks through all aliases for the local host and the loopback
        !            39:  * pseudo-host.
        !            40:  *
        !            41:  * Revision 1.2  1992/02/18  14:43:21  kennykb
        !            42:  * Fix for bug 920218.1 in `History' file.
        !            43:  *
        !            44:  * Revision 1.1  1992/02/14  19:57:51  kennykb
        !            45:  * Initial revision
        !            46:  *
        !            47:  */
        !            48: 
        !            49: static char copyright [] = 
        !            50:   "Copyright (C) 1992 General Electric. All rights reserved."          ;
        !            51: 
        !            52: /*
        !            53:  *   Permission to use, copy, modify, and distribute this
        !            54:  *   software and its documentation for any purpose and without
        !            55:  *   fee is hereby granted, provided that the above copyright
        !            56:  *   notice appear in all copies and that both that copyright
        !            57:  *   notice and this permission notice appear in supporting
        !            58:  *   documentation, and that the name of General Electric not be used in
        !            59:  *   advertising or publicity pertaining to distribution of the
        !            60:  *   software without specific, written prior permission.
        !            61:  *   General Electric makes no representations about the suitability of
        !            62:  *   this software for any purpose.  It is provided "as is"
        !            63:  *   without express or implied warranty.
        !            64:  *
        !            65:  *   This work was supported by the DARPA Initiative in Concurrent
        !            66:  *   Engineering (DICE) through DARPA Contract MDA972-88-C-0047.
        !            67:  */
        !            68: 
        !            69: #include <errno.h>
        !            70: #include <sys/types.h>
        !            71: #include <sys/ioctl.h>
        !            72: #include <sys/socket.h>
        !            73: #include <netinet/in.h>
        !            74: #include <netdb.h>
        !            75: #include <arpa/inet.h>
        !            76: 
        !            77: /* Only some copies of netinet/in.h have the following defined. */
        !            78: 
        !            79: #ifndef INADDR_LOOPBACK
        !            80: #ifdef __STDC__
        !            81: #define INADDR_LOOPBACK 0x7f000001UL
        !            82: #else
        !            83: #define INADDR_LOOPBACK (unsigned long) 0x7f000001L
        !            84: #endif /* __STDC__ */
        !            85: #endif /* INADDR_LOOPBACK */
        !            86: 
        !            87: #include <signal.h>
        !            88: 
        !            89: #include <tclInt.h>
        !            90: #include <tclUnix.h>
        !            91: #include <tk.h>
        !            92: #include "tkTCP.h"
        !            93: 
        !            94: /* Kernel calls */
        !            95: 
        !            96: /* There doesn't seem to be any place to get these....
        !            97:  * certainly not a portable one.
        !            98:  */
        !            99: 
        !           100: extern int accept _ANSI_ARGS_((int, struct sockaddr *, int *));
        !           101: extern int bind _ANSI_ARGS_((int, const struct sockaddr *, int));
        !           102: extern int close _ANSI_ARGS_((int));
        !           103: extern int connect _ANSI_ARGS_((int, const struct sockaddr *, int));
        !           104: extern int gethostname _ANSI_ARGS_((char *, int));
        !           105: extern int getsockname _ANSI_ARGS_((int, struct sockaddr *, int *));
        !           106: extern int ioctl _ANSI_ARGS_((int, int, char *));
        !           107: extern int listen _ANSI_ARGS_((int, int));
        !           108: extern int read _ANSI_ARGS_((int, char *, int));
        !           109: extern int select _ANSI_ARGS_((int, fd_set *, fd_set *, fd_set *,
        !           110:                               struct timeval *));
        !           111: extern int socket _ANSI_ARGS_((int, int, int));
        !           112: extern int getdtablesize _ANSI_ARGS_((void));
        !           113: 
        !           114: 
        !           115: /* Configuration parameters */
        !           116: 
        !           117: /*
        !           118:  * TCP_LISTEN_BACKLOG gives the maximum backlog of connection requests
        !           119:  * that may be queued for any server
        !           120:  */
        !           121: 
        !           122: #define TCP_LISTEN_BACKLOG 3
        !           123: 
        !           124: /* Internal data structures */
        !           125: 
        !           126: /*
        !           127:  * For each server that is established in any interpreter, there's a
        !           128:  * record of the following type.  Note that only one server may be
        !           129:  * running at a time in any interpreter, unless the Tk services are
        !           130:  * available for event management.
        !           131:  */
        !           132: 
        !           133: typedef struct tcp_ServerData {
        !           134:   Tcl_Interp *         interp; /* Interpreter in which connections */
        !           135:                                /* are processed. */
        !           136:   char                 name[ 16 ];
        !           137:                                /* Name of the server object. */
        !           138:   int                  socketfd;
        !           139:                                /* Filedescriptor of the socket at */
        !           140:                                /* which the server listens for connections */
        !           141:   char *               command;
        !           142:                                /* Command to be executed (using */
        !           143:                                /* Tcl_Eval) when a connection request */
        !           144:                                /* arrives. */
        !           145:   Tcl_FreeProc *       freeCommand;
        !           146:                                /* Procedure to free the command when */
        !           147:                                /* it's no longer needed. */
        !           148:   int                  stopFlag;
        !           149:                                /* Flag == TRUE if the server is trying */
        !           150:                                /* to shut down. */
        !           151:   int                  raw;    /* Flag == TRUE if for raw socket mode. */
        !           152:   struct tcp_ClientData * firstClient;
        !           153:                                /* First in the list of clients at this */
        !           154:                                /* server */
        !           155:   struct tcp_ServerData * next, * prev;
        !           156:                                /* Linkage in the list of all active servers */
        !           157: } Tcp_ServerData;
        !           158: 
        !           159: /*
        !           160:  * Each client of a server will have a record of the following type.
        !           161:  */
        !           162: 
        !           163: typedef struct tcp_ClientData {
        !           164:   struct tcp_ServerData * server;
        !           165:                                /* Server to which the client belongs */
        !           166:   char                 name [16];
        !           167:                                /* Name of the client */
        !           168:   int                  socketfd;
        !           169:                                /* Filedescriptor of the socket of the */
        !           170:                                /* the client's connection. */
        !           171:   struct sockaddr_in   peeraddr;
        !           172:                                /* IP address from which the client */
        !           173:                                /* established the connection. */
        !           174:   char *               command;
        !           175:                                /* Command to execute when the client */
        !           176:                                /* sends a message */
        !           177:   Tcl_FreeProc *       freeCommand;
        !           178:                                /* Procedure to free the command when it's */
        !           179:                                /* no longer needed */
        !           180:   Tcl_CmdBuf           inputBuffer;
        !           181:                                /* Buffer where client commands are stored */
        !           182:   char *               resultString;
        !           183:                                /* Result of executing a command on the */
        !           184:                                /* client */
        !           185:   char *               resultPointer;
        !           186:                                /* Pointer to the portion of resultString */
        !           187:                                /* that remains to be transmitted back */
        !           188:                                /* to the client */
        !           189:   Tcl_FreeProc *       freeResultString;
        !           190:                                /* Procedure to free the result string when */
        !           191:                                /* it's no longer needed. */
        !           192:   int                  activeFlag;
        !           193:                                /* Flag == 1 iff a command is pending on */
        !           194:                                /* this client. */
        !           195:   int                  closeFlag;
        !           196:                                /* Flag == 1 if the client should be closed */
        !           197:                                /* once its result has been returned. */
        !           198:   struct tcp_ClientData *next, *prev;
        !           199:                                /* Next and previous entries in the list of */
        !           200:                                /* clients at this server */
        !           201: } Tcp_ClientData;
        !           202: 
        !           203: /* Static variables in this file */
        !           204: 
        !           205: static char * tcpCurrentClient = NULL;
        !           206:                                /* The name of the client for which a */
        !           207:                                /* command is being processed. */
        !           208: static Tcp_ServerData * tcpFirstServer = NULL;
        !           209:                                /* Pointer to the first in a list of */
        !           210:                                /* servers active in the current process. */
        !           211: 
        !           212: /* Declarations for static functions within this file. */
        !           213: 
        !           214: /* Static procedures in this file */
        !           215: 
        !           216: static void simpleDeleteFileHandler1 _ANSI_ARGS_((ClientData, int));
        !           217: 
        !           218: static void simpleDeleteFileHandler2 _ANSI_ARGS_((ClientData));
        !           219: 
        !           220: static int
        !           221: tcpClientCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           222:                              int argc, char * * argv));
        !           223: 
        !           224: static int
        !           225: tcpConnectCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           226:                              int argc, char * * argv));
        !           227: 
        !           228: static int
        !           229: tcpEvalCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           230:                            int argc, char * * argv));
        !           231: 
        !           232: static int
        !           233: tcpLoginCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           234:                             int argc, char * * argv));
        !           235: 
        !           236: static int
        !           237: tcpMainLoopCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           238:                                int argc, char * * argv));
        !           239: 
        !           240: static int
        !           241: tcpPollCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           242:                            int argc, char * * argv));
        !           243: 
        !           244: static int
        !           245: tcpServerCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           246:                              int argc, char * * argv));
        !           247: 
        !           248: static int
        !           249: tcpServersCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           250:                              int argc, char * * argv));
        !           251: static int
        !           252: tcpWaitCommand _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           253:                             int argc, char * * argv));
        !           254: 
        !           255: static int
        !           256: tcpServerObjectCmd _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           257:                                int argc, char * * argv));
        !           258: static void
        !           259: deleteTcpServerObjectCmd _ANSI_ARGS_((ClientData clientData));
        !           260: 
        !           261: static int
        !           262: tcpServerObjectAcceptCmd _ANSI_ARGS_((ClientData clientData,
        !           263:                                      Tcl_Interp * interp, int argc,
        !           264:                                      char * * argv));
        !           265: 
        !           266: static int
        !           267: tcpServerObjectClientsCmd _ANSI_ARGS_((ClientData clientData,
        !           268:                                       Tcl_Interp * interp, int argc,
        !           269:                                       char * * argv));
        !           270: 
        !           271: static int
        !           272: tcpServerObjectConfigCmd _ANSI_ARGS_((ClientData clientData,
        !           273:                                      Tcl_Interp * interp, int argc,
        !           274:                                      char * * argv));
        !           275: 
        !           276: static int
        !           277: tcpServerObjectStartCmd _ANSI_ARGS_((ClientData clientData,
        !           278:                                     Tcl_Interp * interp, int argc,
        !           279:                                     char * * argv));
        !           280: 
        !           281: static int
        !           282: tcpServerObjectStopCmd _ANSI_ARGS_((ClientData clientData,
        !           283:                                    Tcl_Interp * interp, int argc,
        !           284:                                    char * * argv));
        !           285: 
        !           286: static void
        !           287: tcpDeleteServer _ANSI_ARGS_((Tcp_ServerData * server));
        !           288: 
        !           289: static int
        !           290: tcpServerObjectConfig _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           291:                                   int argc, char * * argv));
        !           292: 
        !           293: static int
        !           294: tcpClientObjectCmd _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           295:                                int argc, char * * argv));
        !           296: 
        !           297: static int
        !           298: tcpClientObjectCloseCmd _ANSI_ARGS_((ClientData clientData,
        !           299:                                     Tcl_Interp * interp,
        !           300:                                     int argc, char * * argv));
        !           301: 
        !           302: static int
        !           303: tcpClientObjectCommandCmd _ANSI_ARGS_((ClientData clientData,
        !           304:                                       Tcl_Interp * interp,
        !           305:                                       int argc, char * * argv));
        !           306: 
        !           307: static int
        !           308: tcpClientObjectDoCmd _ANSI_ARGS_((ClientData clientData, Tcl_Interp * interp,
        !           309:                                  int argc, char * * argv));
        !           310: 
        !           311: static int
        !           312: tcpClientObjectHostnameCmd _ANSI_ARGS_((ClientData clientData,
        !           313:                                        Tcl_Interp * interp,
        !           314:                                        int argc, char * * argv));
        !           315: 
        !           316: static int
        !           317: tcpClientObjectServerCmd _ANSI_ARGS_((ClientData clientData,
        !           318:                                      Tcl_Interp * interp,
        !           319:                                      int argc, char * * argv));
        !           320: 
        !           321: static void
        !           322: deleteTcpClientObjectCmd _ANSI_ARGS_((ClientData clientData));
        !           323: 
        !           324: static int
        !           325: tcpConnectionObjectCmd _ANSI_ARGS_((ClientData clientData,
        !           326:                                    Tcl_Interp * interp,
        !           327:                                    int argc, char * * argv));
        !           328: 
        !           329: static int
        !           330: tcpConnectionObjectCloseCmd _ANSI_ARGS_((ClientData clientData,
        !           331:                                         Tcl_Interp * interp,
        !           332:                                         int argc, char * * argv));
        !           333: 
        !           334: static int
        !           335: tcpConnectionObjectSendCmd _ANSI_ARGS_((ClientData clientData,
        !           336:                                        Tcl_Interp * interp,
        !           337:                                        int argc, char * * argv));
        !           338: 
        !           339: static void
        !           340: deleteTcpConnectionObjectCmd _ANSI_ARGS_((ClientData clientData));
        !           341: 
        !           342: static void
        !           343: tcpServerAcceptConnection _ANSI_ARGS_((ClientData clientData, int mask));
        !           344: 
        !           345: static void
        !           346: tcpReturnResultToClient _ANSI_ARGS_((Tcp_ClientData * client,
        !           347:                                     Tcl_Interp * interp,
        !           348:                                     int status, int closeflag));
        !           349: 
        !           350: static void
        !           351: tcpWriteResultToClient _ANSI_ARGS_((ClientData clientData, int mask));
        !           352: 
        !           353: static void
        !           354: tcpClientReadError _ANSI_ARGS_((Tcp_ClientData * client));
        !           355: 
        !           356: static void
        !           357: tcpClientWriteError _ANSI_ARGS_((Tcp_ClientData * client));
        !           358: 
        !           359: static void
        !           360: tcpPrepareClientForInput _ANSI_ARGS_((Tcp_ClientData * client));
        !           361: 
        !           362: static void
        !           363: tcpReceiveClientInput _ANSI_ARGS_((ClientData clientData, int mask));
        !           364: 
        !           365: static void
        !           366: tcpCloseClient _ANSI_ARGS_((Tcp_ClientData * client));
        !           367: 
        !           368: static int
        !           369: tcpTrustedHost _ANSI_ARGS_((char * hostname));
        !           370: 
        !           371: static int
        !           372: tcpSendCmdToServer _ANSI_ARGS_((Tcl_Interp * interp, int s, char * message));
        !           373: 
        !           374: static int
        !           375: tcpReceiveResultFromServer _ANSI_ARGS_((Tcl_Interp * interp, int s));
        !           376: 
        !           377: /*
        !           378:  * simpleReportBackgroundError --
        !           379:  *
        !           380:  *     This procedure is invoked to report a Tcl error in the background,
        !           381:  * when TCL_ERROR has been passed out to the outermost level.
        !           382:  *
        !           383:  *     It tries to run `bgerror' giving it  the error message.  If this
        !           384:  * fails, it reports the problem on stderr.
        !           385:  */
        !           386: 
        !           387: void
        !           388: simpleReportBackgroundError (interp)
        !           389:      Tcl_Interp * interp;
        !           390: {
        !           391: 
        !           392:   char *argv[2];
        !           393:   char *command;
        !           394:   char *error;
        !           395:   char *errorInfo, *tmp;
        !           396:   int status;
        !           397:   int unixStatus;
        !           398: 
        !           399:   /* Get the error message out of the interpreter. */
        !           400: 
        !           401:   error = (char *) ckalloc (strlen (interp -> result) + 1);
        !           402:   strcpy (error, interp -> result);
        !           403: 
        !           404:   /* Get errorInfo, too */
        !           405: 
        !           406:   tmp = Tcl_GetVar (interp, "errorInfo", TCL_GLOBAL_ONLY);
        !           407:   if (tmp == NULL) {
        !           408:     errorInfo = error;
        !           409:   } else {
        !           410:     errorInfo = (char *) ckalloc (strlen (tmp) + 1);
        !           411:     strcpy (errorInfo, tmp);
        !           412:   }
        !           413: 
        !           414:   /* Build a `bgerror' command to report the error */
        !           415: 
        !           416:   argv[0] = "bgerror";
        !           417:   argv[1] = error;
        !           418:   command = Tcl_Merge (2, argv);
        !           419: 
        !           420:   /* Try to run the command */
        !           421: 
        !           422:   status = Tcl_Eval (interp, command, 0, (char **) NULL);
        !           423: 
        !           424:   if (status != TCL_OK) {
        !           425: 
        !           426:     /* Command failed.  Report the problem to stderr. */
        !           427: 
        !           428:     tmp = Tcl_GetVar (interp, "errorInfo", TCL_GLOBAL_ONLY);
        !           429:     if (tmp == NULL) {
        !           430:       tmp = interp -> result;
        !           431:     }
        !           432:     unixStatus = fprintf (stderr, "\n\
        !           433: ------------------------------------------------------------------------\n\
        !           434: Tcl interpreter detected a background error.\n\
        !           435: Original error:\n\
        !           436: %s\n\
        !           437: \n\
        !           438: User \"bgerror\" procedure failed to handle the background error.\n\
        !           439: Error in bgerror:\n\
        !           440: %s\n",
        !           441:             errorInfo, tmp);
        !           442:     if (unixStatus < 0) {
        !           443:       abort ();
        !           444:     }
        !           445:   }
        !           446: 
        !           447:   Tcl_ResetResult (interp);
        !           448: 
        !           449:   free (command);
        !           450: 
        !           451:   ckfree (error);
        !           452: 
        !           453:   if (errorInfo != error) {
        !           454:     ckfree (errorInfo);
        !           455:   }
        !           456: }
        !           457: 
        !           458: /*
        !           459:  * simpleCreateFileHandler --
        !           460:  *
        !           461:  *     This procedure is invoked to create a handle to cause a callback
        !           462:  *     whenever a condition (readable, writable, exception) is
        !           463:  *     present on a given file.
        !           464:  *
        !           465:  *     In the Tk environment, the file handler is created using Tk's
        !           466:  *     Tk_CreateFileHandler procedure, and the callback takes place
        !           467:  *     from the Tk main loop.  In a non-Tk environment, a
        !           468:  *     Tcp_FileHandler structure is created to describe the file, and
        !           469:  *     this structure is linked to a chain of such structures
        !           470:  *     processed by the server main loop.
        !           471:  */
        !           472: 
        !           473: void
        !           474: simpleCreateFileHandler (fd, mask, proc, clientData)
        !           475:      int fd;
        !           476:      int mask;
        !           477:      Tk_FileProc * proc;
        !           478:      ClientData clientData;
        !           479: {
        !           480:   Tk_CreateFileHandler (fd, mask, (Tk_FileProc *) proc, clientData);
        !           481: 
        !           482:   /* It is possible that we have a file handler scheduled for deletion.
        !           483:    * This deletion has to be cancelled if we've requested creation of
        !           484:    * another one.
        !           485:    */
        !           486: 
        !           487:   Tk_CancelIdleCall ((Tk_IdleProc *) simpleDeleteFileHandler2,
        !           488:                     (ClientData) fd);
        !           489: }
        !           490: 
        !           491: /*
        !           492:  * simpleDeleteFileHandler --
        !           493:  *
        !           494:  *     This function is invoked when the program is no longer interested in
        !           495:  * handling events on a file.  It removes any outstanding handler on the file.
        !           496:  *
        !           497:  *     The function is a little tricky because a file handler on the file may
        !           498:  * be active.  In a non-Tk environment, this is simple; the SIMPLE_DELETE flag
        !           499:  * is set in the handler's mask, and the main loop deletes the handler once
        !           500:  * it is quiescent.  In Tk, the event loop won't do that, so what we do
        !           501:  * is set a DoWhenIdle to delete the handler and return.  The DoWhenIdle
        !           502:  * gets called back from the Tk event loop at a time that the handler is
        !           503:  * quiescent, and deletes the handler.
        !           504:  */
        !           505: 
        !           506: void
        !           507: simpleDeleteFileHandler (fd)
        !           508:      int fd;
        !           509: {
        !           510:   /* First of all, we have to zero the file's mask to avoid calling the same
        !           511:      handler over again if the file is still ready. */
        !           512:   Tk_CreateFileHandler (fd, 0, (Tk_FileProc *) simpleDeleteFileHandler1,
        !           513:                        (ClientData) NULL);
        !           514:   Tk_DoWhenIdle ((Tk_IdleProc *) simpleDeleteFileHandler2,
        !           515:                 (ClientData) fd);
        !           516: }
        !           517: 
        !           518: 
        !           519: /* ARGSUSED */
        !           520: static void
        !           521: simpleDeleteFileHandler1 (clientData, mask)
        !           522:      ClientData clientData;
        !           523:      int mask;
        !           524: {
        !           525:   (void) fprintf (stderr, "in simpleDeleteFileHandler1: bug in tkEvent.c");
        !           526:   abort ();
        !           527: }
        !           528: 
        !           529: static void
        !           530: simpleDeleteFileHandler2 (clientData)
        !           531:      ClientData clientData;
        !           532: {
        !           533:   int fd = (int) clientData;
        !           534: 
        !           535:   Tk_DeleteFileHandler (fd);
        !           536: }
        !           537: 
        !           538: /*
        !           539:  *----------------------------------------------------------------------
        !           540:  * Tk_TcpCmd:
        !           541:  *
        !           542:  * This procedure implements a `tcp' command for Tcl.  It provides the
        !           543:  * top-level actions for TCP/IP connections.
        !           544:  *
        !           545:  * This command is divided into variants, each with its own procedure:
        !           546:  *
        !           547:  *     tcp client
        !           548:  *             Returns the current active client, or an error if there is
        !           549:  *             none.
        !           550:  *     tcp connect host port
        !           551:  *             Establish a connection to a server running at `port' on
        !           552:  *             `host.'
        !           553:  *     tcp eval client command
        !           554:  *             Do default command processing for command "$command",
        !           555:  *             originating at client "$client".
        !           556:  *     tcp login client
        !           557:  *             Do default login processing for $client.
        !           558:  *     tcp mainloop
        !           559:  *             Start the main loop for a server or group of servers.
        !           560:  *     tcp poll
        !           561:  *             Poll for whether servers have work to do.
        !           562:  *     tcp servers
        !           563:  *             Returns a list of the currently active servers.
        !           564:  *     tcp server ?args?
        !           565:  *             Set up a server to run in the current interpreter.
        !           566:  *     tcp wait
        !           567:  *             Wait for a server to have work to do.
        !           568:  *----------------------------------------------------------------------
        !           569:  */
        !           570: 
        !           571: int
        !           572: Tk_TcpCmd (clientData, interp, argc, argv)
        !           573:      ClientData clientData;
        !           574:      Tcl_Interp * interp;
        !           575:      int argc;
        !           576:      char * * argv;
        !           577: {
        !           578:   char c;
        !           579:   unsigned length;
        !           580: 
        !           581:   if (argc < 2) {
        !           582:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [0],
        !           583:                      " command ?args?\"", (char *) NULL);
        !           584:     return TCL_ERROR;
        !           585:   }
        !           586: 
        !           587:   c = argv [1] [0];
        !           588:   length = strlen (argv [1]);
        !           589: 
        !           590:   if ((c == 'c') && (length >= 2) &&
        !           591:       (strncmp (argv [1], "client", length) == 0)) {
        !           592:     return tcpClientCommand (clientData, interp, argc-1, argv+1);
        !           593:   }
        !           594:   if ((c == 'c') && (length >= 2) &&
        !           595:       (strncmp (argv [1], "connect", length) == 0)) {
        !           596:     return tcpConnectCommand (clientData, interp, argc-1, argv+1);
        !           597:   }
        !           598:   if ((c == 'e') && (strncmp (argv [1], "eval", length) == 0)) {
        !           599:     return tcpEvalCommand (clientData, interp, argc-1, argv+1);
        !           600:   }
        !           601:   if ((c == 'l') && (strncmp (argv [1], "login", length) == 0)) {
        !           602:     return tcpLoginCommand (clientData, interp, argc-1, argv+1);
        !           603:   }
        !           604:   if ((c == 'm') && (strncmp (argv [1], "mainloop", length) == 0)) {
        !           605:     return tcpMainLoopCommand (clientData, interp, argc-1, argv+1);
        !           606:   }
        !           607:   if ((c == 'p') && (strncmp (argv [1], "poll", length) == 0)) {
        !           608:     return tcpPollCommand (clientData, interp, argc-1, argv+1);
        !           609:   }
        !           610:   if ((c == 's') && (length >= 7)
        !           611:       && (strncmp (argv [1], "servers", length) == 0)) {
        !           612:     return tcpServersCommand (clientData, interp, argc-1, argv+1);
        !           613:   }
        !           614:   if ((c == 's') && (strncmp (argv [1], "server", length) == 0)) {
        !           615:     return tcpServerCommand (clientData, interp, argc-1, argv+1);
        !           616:   }
        !           617:   if ((c == 'w') && (strncmp (argv [1], "wait", length) == 0)) {
        !           618:     return tcpWaitCommand (clientData, interp, argc-1, argv+1);
        !           619:   }
        !           620:   Tcl_AppendResult (interp, "bad option \"", argv [1],
        !           621:                    "\": should be client, eval, login,",
        !           622:                    " mainloop, poll, servers, server or wait",
        !           623:                    (char *) NULL);
        !           624:   return TCL_ERROR;
        !           625: 
        !           626: }
        !           627: 
        !           628: /*
        !           629:  * tcpClientCommand --
        !           630:  *
        !           631:  *     This procedure is invoked to process the "tcp client" Tcl command.
        !           632:  * It returns the name of the currently-active client, or an error if there
        !           633:  * is none.
        !           634:  */
        !           635: 
        !           636: /* ARGSUSED */
        !           637: static int
        !           638: tcpClientCommand (clientData, interp, argc, argv)
        !           639:      ClientData clientData;
        !           640:      Tcl_Interp * interp;
        !           641:      int argc;
        !           642:      char * * argv;
        !           643: {
        !           644:   /* Check syntax */
        !           645: 
        !           646:   if (argc != 1) {
        !           647:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1], " ",
        !           648:                      argv [0], "\"", (char *) NULL);
        !           649:     return TCL_ERROR;
        !           650:   }
        !           651: 
        !           652:   /* Make sure there is a current client */
        !           653: 
        !           654:   if (tcpCurrentClient == NULL) {
        !           655:     Tcl_SetResult (interp, "no current client", TCL_STATIC);
        !           656:     return TCL_ERROR;
        !           657:   }
        !           658: 
        !           659:   Tcl_SetResult (interp, tcpCurrentClient, TCL_VOLATILE);
        !           660:   return TCL_OK;
        !           661: }
        !           662: 
        !           663: /* tcpConnectCommand --
        !           664:  *
        !           665:  *     This procedure is invoked to process the "tcp connect" Tcl command.
        !           666:  * It takes two arguments: a host name and a port.  It tries to establish a
        !           667:  * connection to the specified port and host.
        !           668:  */
        !           669: 
        !           670: /* ARGSUSED */
        !           671: static int
        !           672: tcpConnectCommand (clientData, interp, argc, argv)
        !           673:      ClientData clientData;
        !           674:      Tcl_Interp * interp;
        !           675:      int argc;
        !           676:      char * * argv;
        !           677: {
        !           678:   struct hostent * host;
        !           679:   struct sockaddr_in sockaddr;
        !           680:   int haddr;
        !           681:   int port;
        !           682:   int status;
        !           683:   int f;
        !           684:   char name [20];
        !           685: 
        !           686:   /* Check syntax */
        !           687: 
        !           688:   if (argc != 3) {
        !           689:     Tcl_AppendResult (interp, "wrong # args, should be \"", argv [-1], " ",
        !           690:                      argv [0], " hostname port#\"", (char *) NULL);
        !           691:     return TCL_ERROR;
        !           692:   }
        !           693: 
        !           694:   /* Decode the host name */
        !           695: 
        !           696:   sockaddr.sin_family = AF_INET;
        !           697:   host = gethostbyname (argv [1]);
        !           698:   if (host != NULL) {
        !           699:     memcpy ((char *) &(sockaddr.sin_addr.s_addr),
        !           700:            (char *) (host -> h_addr_list [0]),
        !           701:            (size_t) (host -> h_length));
        !           702:   } else {
        !           703:     haddr = inet_addr (argv [1]);
        !           704:     if (haddr == -1) {
        !           705:       Tcl_AppendResult (interp, argv[1], ": host unknown", (char *) NULL);
        !           706:       return TCL_ERROR;
        !           707:     }
        !           708:     sockaddr.sin_addr.s_addr = haddr;
        !           709:   }
        !           710: 
        !           711:   /* Decode the port number */
        !           712: 
        !           713:   status = Tcl_GetInt (interp, argv [2], &port);
        !           714:   if (status) return status;
        !           715:   sockaddr.sin_port = htons (port);
        !           716: 
        !           717:   /* Make a socket to talk to the server */
        !           718: 
        !           719:   f = socket (AF_INET, SOCK_STREAM, 0);
        !           720:   if (f < 0) {
        !           721:     Tcl_AppendResult (interp, "can't create socket: ",
        !           722:                      Tcl_UnixError (interp), (char *) NULL);
        !           723:     return TCL_ERROR;
        !           724:   }
        !           725: 
        !           726:   /* Connect to the server */
        !           727: 
        !           728:   status = connect (f, (struct sockaddr *) &sockaddr, sizeof sockaddr);
        !           729:   if (status < 0) {
        !           730:     Tcl_AppendResult (interp, "can't connect to server: ",
        !           731:                      Tcl_UnixError (interp), (char *) NULL);
        !           732:     (void) close (f);
        !           733:     return TCL_ERROR;
        !           734:   }
        !           735: 
        !           736:   /* Get the server's greeting message */
        !           737: 
        !           738:   status = tcpReceiveResultFromServer (interp, f);
        !           739: 
        !           740:   if (status == TCL_OK) {
        !           741: 
        !           742:     /* Stash the greeting, make the connection object and return it. */
        !           743: 
        !           744:     sprintf (name, "tcp_connection_%d", f);
        !           745:     (void) Tcl_SetVar2 (interp, "tcp_greeting", name, interp -> result,
        !           746:                        TCL_GLOBAL_ONLY);
        !           747:     Tcl_CreateCommand (interp, name, (Tcl_CmdProc *) tcpConnectionObjectCmd,
        !           748:                       (ClientData) f,
        !           749:                       (Tcl_CmdDeleteProc *) deleteTcpConnectionObjectCmd);
        !           750:     Tcl_SetResult (interp, name, TCL_VOLATILE);
        !           751:     return TCL_OK;
        !           752:   } else {
        !           753: 
        !           754:     /* Error reading greeting, quit */
        !           755: 
        !           756:     (void) close (f);
        !           757:     return TCL_ERROR;
        !           758:   }
        !           759: }    
        !           760: 
        !           761: /*
        !           762:  * tcpEvalCommand --
        !           763:  *
        !           764:  *     This procedure is invoked to process the "tcp eval" Tcl command.
        !           765:  * "tcp eval" is the default command invoked to process connections once
        !           766:  * a connection has been accepted by "tcp login".
        !           767:  */
        !           768: 
        !           769: /* ARGSUSED */
        !           770: static int
        !           771: tcpEvalCommand (clientData, interp, argc, argv)
        !           772:      ClientData clientData;
        !           773:      Tcl_Interp * interp;
        !           774:      int argc;
        !           775:      char * * argv;
        !           776: {
        !           777:   int status;
        !           778: 
        !           779:   /* Argc == 2 means that we're logging out a client.  Default is to ignore
        !           780:    * the logout.
        !           781:    */
        !           782: 
        !           783:   if (argc == 2) {
        !           784:     return TCL_OK;
        !           785:   }
        !           786: 
        !           787:   /* Three-argument form is a command from a client.  Default is to eval
        !           788:    * the command */
        !           789: 
        !           790:   if (argc != 3) {
        !           791:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1],
        !           792:                      " ", argv [0], " client command\"", (char *) NULL);
        !           793:     return TCL_ERROR;
        !           794:   }
        !           795: 
        !           796:   status = Tcl_Eval (interp, argv [2], 0, (char * *) NULL);
        !           797:   return status;
        !           798: }  
        !           799: 
        !           800: /*
        !           801:  * tcpLoginCommand --
        !           802:  *
        !           803:  *     This procedure is invoked to process the "tcp login" Tcl command.
        !           804:  * It is the default command procedure at initial connection to a server.
        !           805:  * It is invoked with the name of a client.  It returns TCL_OK, together
        !           806:  * with a greeting message, if the login succeeds, and TCL_ERROR, together
        !           807:  * with a denial message, if it fails.
        !           808:  *
        !           809:  *     The authentication procedure is as follows:
        !           810:  *
        !           811:  * - If the client is on the local host, the connection is accepted.
        !           812:  * - If the client's IP address is the same as the local host's IP address,
        !           813:  *   the connection is accepted.
        !           814:  * - Otherwise, the connection is refused.
        !           815:  *
        !           816:  *     Obviously, there are other authentication techniques.  The use can
        !           817:  * replace this command with an arbitrary Tcl script.
        !           818:  */
        !           819: 
        !           820: /*ARGSUSED*/
        !           821: static int
        !           822: tcpLoginCommand (clientData, interp, argc, argv)
        !           823:      ClientData clientData;
        !           824:      Tcl_Interp * interp;
        !           825:      int argc;
        !           826:      char * * argv;
        !           827: {
        !           828:   char * hostName;             /* Name of the client's host */
        !           829:   int status;
        !           830: 
        !           831:   /* Check command syntax */
        !           832: 
        !           833:   if (argc != 2) {
        !           834:     Tcl_AppendResult (interp, "wrong # args; should be \"", argv [-1], " ",
        !           835:                      argv [0], " clientName\"", (char *) NULL);
        !           836:     return TCL_ERROR;
        !           837:   }
        !           838: 
        !           839:   /* Get the hostname by doing $client hostname */
        !           840: 
        !           841:   status = Tcl_VarEval (interp, argv [1], " hostname", (char *) NULL);
        !           842:   if (status == TCL_OK) {
        !           843:     hostName = (char *) ckalloc (strlen (interp -> result) + 1);
        !           844:     strcpy (hostName, interp -> result);
        !           845: 
        !           846:     /* Check that the host is trusted */
        !           847:     
        !           848:     if (tcpTrustedHost (hostName)) {
        !           849: 
        !           850:       /* Change the command to `tcp eval' for next time */
        !           851: 
        !           852:       status = Tcl_VarEval (interp, argv [1], " command {tcp eval}",
        !           853:                            (char *) NULL);
        !           854: 
        !           855: 
        !           856:       if (status == TCL_OK) {
        !           857: 
        !           858:        /* Return a greeting message */
        !           859: 
        !           860:        Tcl_ResetResult (interp);
        !           861:        Tcl_AppendResult (interp, "GE DICE TCP-based Tcl server\n", RCSid,
        !           862:                          "\n", copyright, (char *) NULL);
        !           863: 
        !           864:        return TCL_OK;
        !           865: 
        !           866:       }
        !           867: 
        !           868:     }
        !           869: 
        !           870:     ckfree ((char *) hostName);
        !           871:   }
        !           872: 
        !           873:   /* Host isn't trusted or one of the commands failed. */
        !           874: 
        !           875:   Tcl_SetResult (interp, "Permission denied", TCL_STATIC);
        !           876:   return TCL_ERROR;
        !           877: }
        !           878: 
        !           879: /*
        !           880:  * tcpMainLoopCommand:
        !           881:  *
        !           882:  *     This procedure is invoked in a non-Tk environment when the server
        !           883:  * implementor wishes to use a main loop built into the library.  It
        !           884:  * repeatedly polls ofr work to be done, returning only when the last server
        !           885:  * is closed.
        !           886:  *
        !           887:  *     In a Tk environment, the procedure returns immediately.
        !           888:  */
        !           889: 
        !           890: /*ARGSUSED*/
        !           891: static int
        !           892: tcpMainLoopCommand (clientData, interp, argc, argv)
        !           893:      ClientData clientData;
        !           894:      Tcl_Interp * interp;
        !           895:      int argc;
        !           896:      char * * argv;
        !           897: {
        !           898: 
        !           899:   int status;
        !           900: 
        !           901:   if (argc != 1) {
        !           902:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1],
        !           903:                      " ", argv [0], "\"", (char *) NULL);
        !           904:     return TCL_ERROR;
        !           905:   }
        !           906: 
        !           907:   errno = 0; status = -1;
        !           908: 
        !           909:   /* In a non-Tk environment, errno has a Unix error or 0 for no clients
        !           910:    * or servers.  In a Tk environment, errno is zero at this point.
        !           911:    */
        !           912: 
        !           913:   if (errno != 0) {
        !           914:     Tcl_AppendResult (interp, "select: ", Tcl_UnixError (interp),
        !           915:                      (char *) NULL);
        !           916:     return TCL_ERROR;
        !           917:   }
        !           918: 
        !           919:   return TCL_OK;
        !           920: }
        !           921: 
        !           922: 
        !           923: /*
        !           924:  * tcpPollCommand:
        !           925:  *
        !           926:  *     This procedure is invoked to process the "tcp poll" Tcl
        !           927:  * command.  It requests that pending events for the servers be processed.
        !           928:  * It returns a count of events that were processed successfully.
        !           929:  *
        !           930:  *     In a Tk environment, the procedure reports that no servers are known
        !           931:  * to the event handler.  This is correct -- servers register with Tk, not
        !           932:  * with the simple event handler.
        !           933:  */
        !           934: 
        !           935: /*ARGSUSED*/
        !           936: static int
        !           937: tcpPollCommand (clientData, interp, argc, argv)
        !           938:      ClientData clientData;
        !           939:      Tcl_Interp * interp;
        !           940:      int argc;
        !           941:      char * * argv;
        !           942: {
        !           943:   int status;
        !           944: 
        !           945:   if (argc != 1) {
        !           946:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1],
        !           947:                      " ", argv [0], "\"", (char *) NULL);
        !           948:     return TCL_ERROR;
        !           949:   }
        !           950: 
        !           951:   /* Do the poll */
        !           952: 
        !           953:   errno = 0; status = -1;
        !           954: 
        !           955:   /* Check for trouble */
        !           956: 
        !           957:   if (status < 0) {
        !           958:     if (errno == 0) {
        !           959:       Tcl_SetResult (interp, "no servers known to event handler", TCL_STATIC);
        !           960:     } else {
        !           961:       Tcl_AppendResult (interp, "select: ", Tcl_UnixError (interp),
        !           962:                        (char *) NULL);
        !           963:     }
        !           964:     return TCL_ERROR;
        !           965:   }
        !           966: 
        !           967:   /* Return the number of events processed. */
        !           968: 
        !           969:   sprintf (interp -> result, "%d", status);
        !           970:   return TCL_OK;
        !           971: }
        !           972: 
        !           973: /* tcpServerCommand:
        !           974:  *
        !           975:  *     This procedure is invoked to process the "tcp server" Tcl
        !           976:  * command.  It requests that a server be created to listen at a
        !           977:  * TCP/IP port, whose number may be assigned by the system or
        !           978:  * specified by the user with the "-port" option.
        !           979:  *
        !           980:  *     A command string is supplied for use when the server begins to
        !           981:  * accept connections.  See the documentation of tcpServerObjectCmd
        !           982:  * for a description of the command string.
        !           983:  *
        !           984:  *     If the server is created successfully, the return value will
        !           985:  * be the name of a "server object" that can be used for future
        !           986:  * actions upon the server.  This object will be usable as a Tcl
        !           987:  * command; the command is processed by the tcpServerObjectCmd function.
        !           988:  *
        !           989:  * Syntax:
        !           990:  *     tcp server ?-port #? ?-command string?
        !           991:  * 
        !           992:  * Results:
        !           993:  *     A standard Tcl result.  Return value is the name of the server
        !           994:  *     object, which may be invoked as a Tcl command (see
        !           995:  *     tcpServerObjectCmd for details).
        !           996:  */
        !           997: 
        !           998: /* ARGSUSED */
        !           999: static int
        !          1000: tcpServerCommand (clientData, interp, argc, argv)
        !          1001:      ClientData clientData;
        !          1002:      Tcl_Interp * interp;
        !          1003:      int argc;
        !          1004:      char * * argv;
        !          1005: {
        !          1006:   int unixStatus;
        !          1007:   int one;
        !          1008:   char * message;
        !          1009:   char * nargv [3];
        !          1010:   int nargc;
        !          1011: 
        !          1012:   /* Create a structure to hold the tcp server's description. */
        !          1013: 
        !          1014:   Tcp_ServerData * server =
        !          1015:     (Tcp_ServerData *) ckalloc (sizeof (Tcp_ServerData));
        !          1016: 
        !          1017:   /* Set up the interpreter and the default command. Clear the list of
        !          1018:    * clients. */
        !          1019: 
        !          1020:   server -> interp = interp;
        !          1021:   server -> command = "tcp login";
        !          1022:   server -> freeCommand = TCL_STATIC;
        !          1023:   server -> stopFlag = 0;
        !          1024:   server -> raw = 0;
        !          1025:   server -> firstClient = (Tcp_ClientData *) NULL;
        !          1026: 
        !          1027:   /* Create the socket at which the server will listen. */
        !          1028: 
        !          1029:   server -> socketfd = socket (AF_INET, SOCK_STREAM, 0);
        !          1030:   if (server -> socketfd < 0) {
        !          1031:     Tcl_AppendResult (interp, "can't create socket: ",
        !          1032:                      Tcl_UnixError (interp), (char *) NULL);
        !          1033:   } else {
        !          1034: 
        !          1035:     /* Set up the socket for non-blocking I/O. */
        !          1036: 
        !          1037:     one = 1;
        !          1038:     unixStatus = ioctl (server -> socketfd, FIONBIO, (char *) &one);
        !          1039:     if (unixStatus < 0) {
        !          1040:       Tcl_AppendResult (interp, "can't set non-blocking I/O on socket: ",
        !          1041:                        Tcl_UnixError (interp), (char *) NULL);
        !          1042:     } else {
        !          1043: 
        !          1044:       /* Server structure has been created and socket has been opened.
        !          1045:        * Now configure the server.
        !          1046:        */
        !          1047: 
        !          1048:       if (tcpServerObjectConfig ((ClientData) server, interp, argc, argv)
        !          1049:          == TCL_OK)
        !          1050:        {
        !          1051: 
        !          1052:          /* Link the server on the list of active servers */
        !          1053: 
        !          1054:          if (tcpFirstServer)
        !          1055:            tcpFirstServer -> prev = server;
        !          1056:          server -> next = tcpFirstServer;
        !          1057:          tcpFirstServer = server;
        !          1058:          server -> prev = NULL;
        !          1059: 
        !          1060:          /* Add the server object command */
        !          1061:          
        !          1062:          sprintf (server -> name, "tcp_server_%d", server -> socketfd);
        !          1063: 
        !          1064:          Tcl_CreateCommand (interp, server -> name,
        !          1065:                             (Tcl_CmdProc *) tcpServerObjectCmd,
        !          1066:                             (ClientData) server,
        !          1067:                             (Tcl_CmdDeleteProc *) deleteTcpServerObjectCmd);
        !          1068: 
        !          1069:          Tcl_SetResult (interp, server -> name, TCL_STATIC);
        !          1070:          
        !          1071:          return TCL_OK;
        !          1072: 
        !          1073:        }
        !          1074:     }
        !          1075: 
        !          1076:     /* Error in configuring the server.  Trash the socket. */
        !          1077:     
        !          1078:     unixStatus = close (server -> socketfd);
        !          1079:     if (unixStatus < 0) {
        !          1080:       nargc = 3;
        !          1081:       nargv [0] = "(also failed to close socket: ";
        !          1082:       nargv [1] = Tcl_UnixError (interp);
        !          1083:       nargv [2] = ")";
        !          1084:       message = Tcl_Concat (nargc, nargv);
        !          1085:       Tcl_AddErrorInfo (interp, message);
        !          1086:       free (message);
        !          1087:     }
        !          1088:   }
        !          1089:       
        !          1090:   /* Error in creating the server -- get rid of the data structure */
        !          1091: 
        !          1092:   if (server -> freeCommand != NULL) {
        !          1093:     (*(server -> freeCommand)) (server -> command);
        !          1094:   }
        !          1095:   ckfree ((char *) server);
        !          1096:   return TCL_ERROR;
        !          1097: }
        !          1098: 
        !          1099: /*
        !          1100:  * tcpServersCommand:
        !          1101:  *
        !          1102:  *     The following procedure is invoked to process the `tcp servers' Tcl
        !          1103:  * command.  It returns a list of the servers that are currently known.
        !          1104:  */
        !          1105: 
        !          1106: /* ARGSUSED */
        !          1107: static int
        !          1108: tcpServersCommand (clientData, interp, argc, argv)
        !          1109:      ClientData clientData;
        !          1110:      Tcl_Interp * interp;
        !          1111:      int argc;
        !          1112:      char * * argv;
        !          1113: {
        !          1114:   Tcp_ServerData * server;
        !          1115: 
        !          1116:   /* Check syntax */
        !          1117: 
        !          1118:   if (argc != 1) {
        !          1119:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1], " ",
        !          1120:                      argv [0], "\"", (char *) NULL);
        !          1121:     return TCL_ERROR;
        !          1122:   }
        !          1123: 
        !          1124:   for (server = tcpFirstServer; server != NULL; server = server -> next) {
        !          1125:     Tcl_AppendElement (interp, server -> name, 0);
        !          1126:   }
        !          1127: 
        !          1128:   return TCL_OK;
        !          1129: }
        !          1130: 
        !          1131: /*
        !          1132:  * tcpWaitCommand:
        !          1133:  *
        !          1134:  *     This procedure is invoked to process the "tcp wait" Tcl
        !          1135:  * command.  It requests that the process delay until an event is
        !          1136:  * pending for a TCP server.
        !          1137:  *
        !          1138:  * It returns a count of pending events.
        !          1139:  *
        !          1140:  *     In a Tk environment, the procedure returns an error message stating
        !          1141:  * that no servers are known to the event handler.  This is correct.  The
        !          1142:  * servers register with Tk's event handler, and are not known to the simple
        !          1143:  * event handler.
        !          1144:  */
        !          1145: 
        !          1146: /*ARGSUSED*/
        !          1147: static int
        !          1148: tcpWaitCommand (clientData, interp, argc, argv)
        !          1149:      ClientData clientData;
        !          1150:      Tcl_Interp * interp;
        !          1151:      int argc;
        !          1152:      char * * argv;
        !          1153: {
        !          1154:   int status;
        !          1155: 
        !          1156:   if (argc != 1) {
        !          1157:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1],
        !          1158:                      " ", argv [0], "\"", (char *) NULL);
        !          1159:     return TCL_ERROR;
        !          1160:   }
        !          1161: 
        !          1162:   /* Do the poll */
        !          1163: 
        !          1164:   errno = 0; status = -1;
        !          1165: 
        !          1166:   /* Check for trouble */
        !          1167: 
        !          1168:   if (status < 0) {
        !          1169:     if (errno == 0) {
        !          1170:       Tcl_SetResult (interp, "no servers known to event handler", TCL_STATIC);
        !          1171:     } else {
        !          1172:       Tcl_AppendResult (interp, "select: ", Tcl_UnixError (interp),
        !          1173:                        (char *) NULL);
        !          1174:     }
        !          1175:     return TCL_ERROR;
        !          1176:   }
        !          1177: 
        !          1178:   /* Return the number of events pending. */
        !          1179: 
        !          1180:   sprintf (interp -> result, "%d", status);
        !          1181:   return TCL_OK;
        !          1182: }
        !          1183: 
        !          1184: /*
        !          1185:  * tcpServerObjectCmd --
        !          1186:  *
        !          1187:  *     This procedure is invoked when a command is called on a server
        !          1188:  *     object directly.  It dispatches to the appropriate command processing
        !          1189:  *     procedure to handle the command.
        !          1190:  *
        !          1191:  * $server accept
        !          1192:  *     [Internal call] - Accept a connection.
        !          1193:  * $server clients
        !          1194:  *     Return a list of all clients connected to a server.
        !          1195:  * $server configure ?args?
        !          1196:  *     Revise or query a server's configuration.
        !          1197:  * $server start
        !          1198:  *     Start a server running.
        !          1199:  * $server stop
        !          1200:  *     Terminate a server.
        !          1201:  */
        !          1202: 
        !          1203: static int
        !          1204: tcpServerObjectCmd (clientData, interp, argc, argv)
        !          1205:      ClientData clientData;
        !          1206:      Tcl_Interp * interp;
        !          1207:      int argc;
        !          1208:      char * * argv;
        !          1209: {
        !          1210:   int c;
        !          1211:   unsigned length;
        !          1212: 
        !          1213:   if (argc < 2) {
        !          1214:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [0],
        !          1215:                      " command ?args?\"", (char *) NULL);
        !          1216:     return TCL_ERROR;
        !          1217:   }
        !          1218: 
        !          1219:   c = argv [1] [0];
        !          1220:   length = strlen (argv [1]);
        !          1221:   
        !          1222:   if (c == 'a' && strncmp (argv [1], "accept", length) == 0) {
        !          1223:     return tcpServerObjectAcceptCmd (clientData, interp, argc-1, argv+1);
        !          1224:   }
        !          1225:   if (c == 'c' && length >= 2 && strncmp (argv [1], "clients", length) == 0) {
        !          1226:     return tcpServerObjectClientsCmd (clientData, interp, argc-1, argv+1);
        !          1227:   }
        !          1228:   if (c == 'c' && length >= 2
        !          1229:       && strncmp (argv [1], "configure", length) == 0) {
        !          1230:     return tcpServerObjectConfigCmd (clientData, interp, argc-1, argv+1);
        !          1231:   }
        !          1232:   if (c == 's' && length >= 3 && strncmp (argv [1], "start", length) == 0) {
        !          1233:     return tcpServerObjectStartCmd (clientData, interp, argc-1, argv+1);
        !          1234:   }
        !          1235:   if (c == 's' && length >= 3 && strncmp (argv [1], "stop", length) == 0) {
        !          1236:     return tcpServerObjectStopCmd (clientData, interp, argc-1, argv+1);
        !          1237:   }
        !          1238:   Tcl_AppendResult (interp, argv [0], ": ", "bad option \"", argv [1],
        !          1239:                    "\": should be clients, configure, start, or stop",
        !          1240:                    (char *) NULL);
        !          1241:   return TCL_ERROR;
        !          1242: }
        !          1243: 
        !          1244: /*
        !          1245:  * tcpServerObjectAcceptCmd --
        !          1246:  *
        !          1247:  *     The following procedure handles the `accept' command on a
        !          1248:  *     server object.  It is called in the background by
        !          1249:  *     tcpServerAcceptConnection when a connection request appears on
        !          1250:  *     a server.  It is responsible for creating the client and
        !          1251:  *     accepting the connection request.
        !          1252:  *
        !          1253:  * Results:
        !          1254:  *     Returns a standard TCL result.  The return value is the name
        !          1255:  *     of the client if the call is successful.
        !          1256:  *
        !          1257:  * Side effects:
        !          1258:  *     A Tcl command named after the client object is created.
        !          1259:  */
        !          1260: 
        !          1261: static int
        !          1262: tcpServerObjectAcceptCmd (clientData, interp, argc, argv)
        !          1263:      ClientData clientData;
        !          1264:      Tcl_Interp * interp;
        !          1265:      int argc;
        !          1266:      char * * argv;
        !          1267: {
        !          1268:   register Tcp_ServerData * server = (Tcp_ServerData *) clientData;
        !          1269:   register Tcp_ClientData * client;
        !          1270:   int rubbish;
        !          1271:   int unixStatus;
        !          1272:   int nargc;
        !          1273:   char * nargv [3];
        !          1274:   char * message;
        !          1275: 
        !          1276:   /* Check command syntax */
        !          1277: 
        !          1278:   if (argc != 1) {
        !          1279:     Tcl_AppendResult (interp, "wrong # args, should be \"", argv [-1], " ",
        !          1280:                      argv [0], "\"", (char *) NULL);
        !          1281:     return TCL_ERROR;
        !          1282:   }
        !          1283: 
        !          1284:   /* Create the client data structure */
        !          1285: 
        !          1286:   client = (Tcp_ClientData *) ckalloc (sizeof (Tcp_ClientData));
        !          1287: 
        !          1288:   /* Accept the client's connection request */
        !          1289: 
        !          1290:   rubbish = sizeof (struct sockaddr_in);
        !          1291:   client -> socketfd = accept (server -> socketfd,
        !          1292:                               (struct sockaddr *) &(client -> peeraddr),
        !          1293:                               &rubbish);
        !          1294:   if (client -> socketfd < 0) {
        !          1295:     Tcl_AppendResult (interp, "can't accept connection: ",
        !          1296:                      Tcl_UnixError (interp), (char *) NULL);
        !          1297:     ckfree ((char *) client);
        !          1298:     return TCL_ERROR;
        !          1299:   }
        !          1300: 
        !          1301:   /* Set up the socket for non-blocking I/O */
        !          1302: 
        !          1303:   rubbish = 1;
        !          1304:   unixStatus = ioctl (client -> socketfd, FIONBIO, (char *) &rubbish);
        !          1305:   if (unixStatus < 0) {
        !          1306:     Tcl_AppendResult (interp,
        !          1307:                      "can't set non-blocking I/O on client's socket: ",
        !          1308:                      Tcl_UnixError (interp), (char *) NULL);
        !          1309:     unixStatus = close (client -> socketfd);
        !          1310:     if (unixStatus < 0) {
        !          1311:       nargc = 3;
        !          1312:       nargv [0] = "(also failed to close socket: ";
        !          1313:       nargv [1] = Tcl_UnixError (interp);
        !          1314:       nargv [2] = ")";
        !          1315:       message = Tcl_Concat (nargc, nargv);
        !          1316:       Tcl_AddErrorInfo (interp, message);
        !          1317:       free (message);
        !          1318:     }
        !          1319:     ckfree ((char *) client);
        !          1320:     return TCL_ERROR;
        !          1321:   }
        !          1322: 
        !          1323:   /* Set up the client's description */
        !          1324: 
        !          1325:   client -> server = server;
        !          1326:   sprintf (client -> name, "tcp_client_%d", client -> socketfd);
        !          1327:   client -> command = malloc (strlen (server -> command) + 1);
        !          1328:   client -> freeCommand = (Tcl_FreeProc *) free;
        !          1329:   strcpy (client -> command, server -> command);
        !          1330:   client -> inputBuffer = Tcl_CreateCmdBuf ();
        !          1331:   client -> resultString = client -> resultPointer = (char *) NULL;
        !          1332:   client -> freeResultString = (Tcl_FreeProc *) NULL;
        !          1333:   client -> activeFlag = 0;
        !          1334:   client -> closeFlag = 0;
        !          1335:   client -> next = server -> firstClient;
        !          1336:   if (client -> next != NULL) {
        !          1337:     client -> next -> prev = client;
        !          1338:   }
        !          1339:   client -> prev = NULL;
        !          1340:   server -> firstClient = client;
        !          1341: 
        !          1342:   /* Create the Tcl command for the client */
        !          1343:   
        !          1344:   Tcl_CreateCommand (interp, client -> name,
        !          1345:                     (Tcl_CmdProc *) tcpClientObjectCmd,
        !          1346:                     (ClientData) client,
        !          1347:                     (Tcl_CmdDeleteProc *) deleteTcpClientObjectCmd);
        !          1348: 
        !          1349:   /* Return the client's name */
        !          1350: 
        !          1351:   Tcl_SetResult (interp, client -> name, TCL_STATIC);
        !          1352:   return TCL_OK;
        !          1353: }
        !          1354: 
        !          1355: /*
        !          1356:  * tcpServerObjectClientsCmd --
        !          1357:  *
        !          1358:  *     This procedure in invoked in response to the `clients' command
        !          1359:  * on a TCP server object.  It returns a list of clients for the server.
        !          1360:  */
        !          1361: 
        !          1362: static int
        !          1363: tcpServerObjectClientsCmd (clientData, interp, argc, argv)
        !          1364:      ClientData clientData;
        !          1365:      Tcl_Interp * interp;
        !          1366:      int argc;
        !          1367:      char * * argv;
        !          1368: {
        !          1369:   Tcp_ServerData * server = (Tcp_ServerData *) clientData;
        !          1370:   Tcp_ClientData * client;
        !          1371: 
        !          1372:   /* Check syntax */
        !          1373: 
        !          1374:   if (argc != 1) {
        !          1375:     Tcl_AppendResult (interp, "wrong # args, should be\"", argv [-1], " ",
        !          1376:                      argv [0], "\"", (char *) NULL);
        !          1377:     return TCL_ERROR;
        !          1378:   }
        !          1379: 
        !          1380:   for (client = server -> firstClient; client != NULL;
        !          1381:        client = client -> next) {
        !          1382:     Tcl_AppendElement (interp, client -> name, 0);
        !          1383:   }
        !          1384: 
        !          1385:   return TCL_OK;
        !          1386: }
        !          1387: 
        !          1388: /*
        !          1389:  * tcpServerObjectConfigCmd --
        !          1390:  *
        !          1391:  *     This procedure is invoked in response to the `config' command
        !          1392:  *     on a TCP server object.  With no arguments, it returns a list
        !          1393:  *     of valid arguments.  With one argument, it returns the current
        !          1394:  *     value of that option.  With multiple arguments, it attempts to
        !          1395:  *     configure the server according to that argument list.
        !          1396:  * Results:
        !          1397:  *     Returns a standard Tcl result.
        !          1398:  */
        !          1399: 
        !          1400: static int
        !          1401: tcpServerObjectConfigCmd (clientData, interp, argc, argv)
        !          1402:      ClientData clientData;
        !          1403:      Tcl_Interp * interp;
        !          1404:      int argc;
        !          1405:      char * * argv;
        !          1406: {
        !          1407:   int unixStatus;
        !          1408:   int c;
        !          1409:   unsigned length;
        !          1410: 
        !          1411:   /* No arguments -- return a list of valid options. */
        !          1412: 
        !          1413:   if (argc <= 1) {
        !          1414:     Tcl_SetResult (interp, "-command -port", TCL_STATIC);
        !          1415:     return TCL_OK;
        !          1416:   }
        !          1417: 
        !          1418:   /* One argument -- query a particular option */
        !          1419: 
        !          1420:   if (argc == 2) {
        !          1421:     register Tcp_ServerData * server = (Tcp_ServerData *) clientData;
        !          1422:     char * arg = argv [1];
        !          1423: 
        !          1424:     if (arg [0] != '-') {
        !          1425:       Tcl_AppendResult (interp, argv [-1], " ", argv [0],
        !          1426:                        ": bad option \"", arg,
        !          1427:                        "\" -- each option must begin with a hyphen.",
        !          1428:                        (char *) NULL);
        !          1429:       return TCL_ERROR;
        !          1430: 
        !          1431:     }
        !          1432: 
        !          1433:     length = strlen (++arg);
        !          1434:     c = arg [0];
        !          1435: 
        !          1436:     if (c == 'c' && strncmp (arg, "command", length) == 0) {
        !          1437: 
        !          1438:       /* Command option -- Get the command name */
        !          1439: 
        !          1440:       Tcl_SetResult (interp, server->name, TCL_STATIC);
        !          1441:       return TCL_OK;
        !          1442: 
        !          1443:     }
        !          1444: 
        !          1445:     if (c == 'p' && strncmp (arg, "port", length) == 0) {
        !          1446: 
        !          1447:       /* Port option -- Get the port number */
        !          1448: 
        !          1449:       struct sockaddr_in portaddr;
        !          1450:       int rubbish = sizeof (struct sockaddr_in);
        !          1451: 
        !          1452:       unixStatus = getsockname (server -> socketfd,
        !          1453:                                (struct sockaddr *) &portaddr, &rubbish);
        !          1454:       if (unixStatus < 0) {
        !          1455:        Tcl_AppendResult (interp, argv [-1], ": can't read port #: ",
        !          1456:                          Tcl_UnixError (interp), (char *) NULL);
        !          1457:        return TCL_ERROR;
        !          1458:       }
        !          1459:       Tcl_ResetResult (interp);
        !          1460:       sprintf (interp -> result, "%d", (int) ntohs (portaddr.sin_port));
        !          1461:       return TCL_OK;
        !          1462:     }
        !          1463:        
        !          1464:     /* Unknown option */
        !          1465: 
        !          1466:     Tcl_AppendResult (interp, argv [-1], ": unknown option \"", arg,
        !          1467:                      "\" -- must be -command or -port", (char *) NULL);
        !          1468:     return TCL_ERROR;
        !          1469:   }
        !          1470: 
        !          1471:   return tcpServerObjectConfig (clientData, interp, argc, argv);
        !          1472: }  
        !          1473: 
        !          1474: /*
        !          1475:  * tcpServerObjectStartCmd --
        !          1476:  *
        !          1477:  *     This procedure is invoked to process the "start" command on a
        !          1478:  *     TCP server object.  It sets the server up so that new
        !          1479:  *     connection requests will create "server-client" objects and
        !          1480:  *     invoke the server's command with them.
        !          1481:  *
        !          1482:  *     If Tk is available, the "start" command returns to the caller.
        !          1483:  *     If Tk is not available, the "start" command immediately enters
        !          1484:  *     a loop that attempts to process the connection events (and
        !          1485:  *     other file events as well).  The loop may be exited by
        !          1486:  *     executing a `stop' command on the server object.  (The `stop'
        !          1487:  *     command also exists in the Tk environment, since there is more
        !          1488:  *     to stopping a server than just breaking out of its event
        !          1489:  *     loop.)
        !          1490: */
        !          1491: 
        !          1492: static int
        !          1493: tcpServerObjectStartCmd (clientData, interp, argc, argv)
        !          1494:      ClientData clientData;
        !          1495:      Tcl_Interp * interp;
        !          1496:      int argc;
        !          1497:      char * * argv;
        !          1498: {
        !          1499:   register Tcp_ServerData * server = (Tcp_ServerData *) clientData;
        !          1500:   int unixStatus;
        !          1501: 
        !          1502:   /* Check command syntax */
        !          1503: 
        !          1504:   if (argc != 1) {
        !          1505:     Tcl_AppendResult (interp, "wrong # args, should be \"", argv [-1], " ",
        !          1506:                      argv [0], "\"", (char *) NULL);
        !          1507:     return TCL_ERROR;
        !          1508:   }
        !          1509: 
        !          1510:   /* Listen at the server's socket */
        !          1511: 
        !          1512:   unixStatus = listen (server -> socketfd, TCP_LISTEN_BACKLOG);
        !          1513:   if (unixStatus < 0) {
        !          1514:     Tcl_AppendResult (interp, argv [-1], ": can't listen at socket: ",
        !          1515:                      Tcl_UnixError (interp), (char *) NULL);
        !          1516:     return TCL_ERROR;
        !          1517:   }
        !          1518: 
        !          1519:   /* Add a file handler to gain control at tcpServerAcceptConnection
        !          1520:    * whenever a client attempts to connect.
        !          1521:    */
        !          1522: 
        !          1523:   simpleCreateFileHandler (server -> socketfd, TK_READABLE,
        !          1524:                           (Tk_FileProc *) tcpServerAcceptConnection,
        !          1525:                           clientData);
        !          1526:   return TCL_OK;
        !          1527: }
        !          1528: 
        !          1529: /*
        !          1530:  * tcpServerObjectStopCmd
        !          1531:  *
        !          1532:  *     This procedure is invoked in response to the `$server stop' Tcl
        !          1533:  * command.  It destroys the server's object command.  Destroying the object
        !          1534:  * command, in turn, attempts to shut down the server in question.  It closes
        !          1535:  * the listen socket, closes all the clients, and sets the `stop' flag for
        !          1536:  * the server itself.  It then calls `tcpServerClose' to try to get rid of
        !          1537:  * the server.
        !          1538:  *
        !          1539:  *     If one or more clients are active, the server does not shut down
        !          1540:  * until they can be closed properly.
        !          1541:  */
        !          1542: 
        !          1543: static int
        !          1544: tcpServerObjectStopCmd (clientData, interp, argc, argv)
        !          1545:      ClientData clientData;
        !          1546:      Tcl_Interp * interp;
        !          1547:      int argc;
        !          1548:      char * * argv;
        !          1549: {
        !          1550:   register Tcp_ServerData * server = (Tcp_ServerData *) clientData;
        !          1551: 
        !          1552:   if (argc != 1) {
        !          1553:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1],
        !          1554:                      " ", argv [0], "\"", (char *) NULL);
        !          1555:     return TCL_ERROR;
        !          1556:   }
        !          1557: 
        !          1558:   /* Delete the server command */
        !          1559: 
        !          1560:   Tcl_DeleteCommand (interp, server -> name);
        !          1561: 
        !          1562:   return TCL_OK;
        !          1563: }
        !          1564: 
        !          1565: /*
        !          1566:  * deleteTcpServerObjectCmd --
        !          1567:  *
        !          1568:  *     This procedure is called when a server's object command is deleted.
        !          1569:  *
        !          1570:  *     It is the first procedure called when a server is shut down.  It
        !          1571:  * closes the listen socket and deletes its file handler.  It also attempts
        !          1572:  * to close all the clients.
        !          1573:  *
        !          1574:  *     It may be that a client needs to be able to complete a data transfer
        !          1575:  * before it can be closed.  In this case, the `close flag' for the client is
        !          1576:  * set.  The client will be deleted when it reaches a quiescent point.
        !          1577:  *
        !          1578:  *     Once all the clients are gone, tcpDeleteServer removes the server's
        !          1579:  * client data structure.
        !          1580:  */
        !          1581: 
        !          1582: static void
        !          1583: deleteTcpServerObjectCmd (clientData)
        !          1584:      ClientData clientData;
        !          1585: {
        !          1586:   register Tcp_ServerData * server = (Tcp_ServerData *) clientData;
        !          1587:   register Tcp_ClientData * client, * nextClient;
        !          1588: 
        !          1589:   /* Close the listen socket and delete its handler */
        !          1590: 
        !          1591:   simpleDeleteFileHandler (server -> socketfd);
        !          1592:   (void) close (server -> socketfd);
        !          1593:   server -> socketfd = -1;
        !          1594: 
        !          1595:   /* Close all clients */
        !          1596: 
        !          1597:   for (client = server -> firstClient; client != NULL; client = nextClient) {
        !          1598:     nextClient = client -> next;
        !          1599:     if (client -> activeFlag)
        !          1600:       client -> closeFlag = 1;
        !          1601:     else
        !          1602:       tcpCloseClient (client);
        !          1603:   }
        !          1604: 
        !          1605:   /* Remove the server from the list of servers. */
        !          1606: 
        !          1607:   if (server -> next != NULL)
        !          1608:     server -> next -> prev = server -> prev;
        !          1609:   if (server -> prev != NULL)
        !          1610:     server -> prev -> next = server -> next;
        !          1611:   else
        !          1612:     tcpFirstServer = server -> next;
        !          1613: 
        !          1614:   /* If all clients are closed, get to tcpDeleteServer now.  Otherwise, set
        !          1615:    * the server's stop flag and return.
        !          1616:    */
        !          1617: 
        !          1618:   if (server -> firstClient == NULL) {
        !          1619:     tcpDeleteServer (server);
        !          1620:   } else {
        !          1621:     server -> stopFlag = 1;
        !          1622:   }
        !          1623: }
        !          1624: 
        !          1625: /*
        !          1626:  * tcpDeleteServer --
        !          1627:  *
        !          1628:  *     This procedure is invoked as the final phase of deleting a TCP server.
        !          1629:  * When execution gets here, the server's listen socket has been closed and
        !          1630:  * the handler has been removed.  The server's object command has been deleted.
        !          1631:  * The server has been removed from the list of active servers.  All the
        !          1632:  * server's clients have been closed.  The server's login command has been
        !          1633:  * deleted.  All that remains is to deallocate the server's data structures.
        !          1634:  */
        !          1635: 
        !          1636: static void
        !          1637: tcpDeleteServer (server)
        !          1638:      Tcp_ServerData * server;
        !          1639: {
        !          1640:   /* Get rid of the server's initial command */
        !          1641: 
        !          1642:   if (server -> command != NULL && server -> freeCommand != NULL) {
        !          1643:     (*(server -> freeCommand)) (server -> command);
        !          1644:   }
        !          1645: 
        !          1646:   /* Get rid of the server's own data structure */
        !          1647: 
        !          1648:   (void) ckfree ((char *) server);
        !          1649: }
        !          1650: 
        !          1651: /*
        !          1652:  * tcpServerObjectConfig --
        !          1653:  *
        !          1654:  *     This procedure is invoked to configure a TCP server object.
        !          1655:  *     It may be called from tcpServerCommand when the server is
        !          1656:  *     first being created, or else from tcpServerObjectCmd if the
        !          1657:  *     server object is called with the "config" option.
        !          1658:  *
        !          1659:  *     In any case, the arguments are expected to contain zero or
        !          1660:  *     more of the following:
        !          1661:  *
        !          1662:  *     -port <number>
        !          1663:  *             Requests that the server listen at a specific port.
        !          1664:  *             Default is whatever the system assigns.
        !          1665:  *
        !          1666:  *     -command <string>
        !          1667:  *             Specifies the initial command used when a client
        !          1668:  *             first connects to the server.  The command is
        !          1669:  *             concatenated with the name of a "server-client" object
        !          1670:  *             that identifies the client, and then called:
        !          1671:  *                     command client
        !          1672:  *             Default is "tcp login"
        !          1673:  *
        !          1674:  *     -raw
        !          1675:  *             Puts the server in raw socket mode.
        !          1676:  *
        !          1677:  * Result:
        !          1678:  *     A standard TCL result.
        !          1679:  */
        !          1680: 
        !          1681: static int
        !          1682: tcpServerObjectConfig (clientData, interp, argc, argv)
        !          1683:      ClientData clientData;
        !          1684:      Tcl_Interp * interp;
        !          1685:      int argc;
        !          1686:      char * * argv;
        !          1687: {
        !          1688: 
        !          1689:   register Tcp_ServerData * server = (Tcp_ServerData *) clientData;
        !          1690: 
        !          1691:   int status;
        !          1692:   int unixStatus;
        !          1693: 
        !          1694:   /* On entry, argc shows one plus the number of parameters.  Argv[-1] */
        !          1695:   /* and argv[0] give the command that got us here: either "tcp */
        !          1696:   /* server" or else "serverName config" */
        !          1697: 
        !          1698:   int a;
        !          1699:   unsigned length;
        !          1700:   int c;
        !          1701: 
        !          1702:   /* Step through the parameters */
        !          1703: 
        !          1704:   for (a = 1; a < argc; ++a) {
        !          1705:     char * arg = argv [a];
        !          1706: 
        !          1707:     if (arg [0] != '-') {
        !          1708:       Tcl_AppendResult (interp, argv [-1], ": bad option \"", arg,
        !          1709:                        "\" -- each option must begin with a hyphen.",
        !          1710:                        (char *) NULL);
        !          1711:       return TCL_ERROR;
        !          1712:     } else {
        !          1713: 
        !          1714:       length = strlen (++arg);
        !          1715:       c = arg [0];
        !          1716: 
        !          1717:       if (c == 'c' && strncmp (arg, "command", length) == 0) {
        !          1718: 
        !          1719:        /* Command option -- Get the command name */
        !          1720: 
        !          1721:        ++a;
        !          1722:        if (a >= argc) {
        !          1723:          Tcl_AppendResult (interp, argv [-1],
        !          1724:                            ": \"-command\" must be followed by a string.",
        !          1725:                            (char *) NULL);
        !          1726:          return TCL_ERROR;
        !          1727:        }
        !          1728: 
        !          1729:        /* Free the old command name */
        !          1730: 
        !          1731:        if (server -> freeCommand != NULL) {
        !          1732:          (*(server -> freeCommand)) (server -> command);
        !          1733:        }
        !          1734: 
        !          1735:        /* Put in the new command name */
        !          1736: 
        !          1737:        server -> command = (char *) malloc (strlen (argv [a]) + 1);
        !          1738:        strcpy (server -> command, argv [a]);
        !          1739:        server -> freeCommand = (Tcl_FreeProc *) free;
        !          1740: 
        !          1741:       } else if (c == 'p' && strncmp (arg, "port", length) == 0) {
        !          1742: 
        !          1743:        /* Port option -- get the port number */
        !          1744: 
        !          1745:        char * portstr;
        !          1746:        int portno;
        !          1747:        struct sockaddr_in portaddr;
        !          1748: 
        !          1749:        ++a;
        !          1750:        if (a >= argc) {
        !          1751:          Tcl_AppendResult (interp, argv [-1],
        !          1752:                            ": \"-port\" must be followed by a number.",
        !          1753:                            (char *) NULL);
        !          1754:          return TCL_ERROR;
        !          1755:        }
        !          1756:        portstr = argv [a];
        !          1757:        status = Tcl_GetInt (interp, portstr, &portno);
        !          1758:        if (status) return status;
        !          1759: 
        !          1760:        /* Set the port number */
        !          1761: 
        !          1762:        memset ((void *) & portaddr, 0, sizeof (struct sockaddr_in));
        !          1763:        portaddr.sin_port = htons (portno);
        !          1764:        unixStatus = bind (server -> socketfd,
        !          1765:                           (struct sockaddr *) &portaddr,
        !          1766:                           sizeof (struct sockaddr_in));
        !          1767:        if (unixStatus < 0) {
        !          1768:          Tcl_AppendResult (interp, argv [-1],
        !          1769:                            ": can't set port number: ",
        !          1770:                            Tcl_UnixError (interp), (char *) NULL);
        !          1771:          return TCL_ERROR;
        !          1772:        }
        !          1773: 
        !          1774:       } else if (c == 'r' && strncmp (arg, "raw", length) == 0) {
        !          1775: 
        !          1776:        /* raw option -- set raw socket mode */
        !          1777: 
        !          1778:        server -> raw = 1;
        !          1779: 
        !          1780:       } else {
        !          1781: 
        !          1782:        /* Unknown option */
        !          1783: 
        !          1784:        Tcl_AppendResult (interp, argv [-1],
        !          1785:                          ": unknown option \"", arg - 1,
        !          1786:                          "\" -- must be -command or -port", (char *) NULL);
        !          1787:        return TCL_ERROR;
        !          1788:       }
        !          1789:     }
        !          1790:   }
        !          1791: 
        !          1792:   Tcl_SetResult (interp, server -> name, TCL_STATIC);
        !          1793:   return TCL_OK;
        !          1794: }
        !          1795: 
        !          1796: /*
        !          1797:  * tcpClientObjectCmd --
        !          1798:  *
        !          1799:  *     This procedure handles the object command for a Tcp client (on
        !          1800:  *     the server side).  It takes several forms:
        !          1801:  *             $client command ?command?
        !          1802:  *                     With no arguments, returns the client's
        !          1803:  *                     current command.  With arguments, replaces the
        !          1804:  *                     client's command with the arguments
        !          1805:  *             $client close
        !          1806:  *                     Deletes the client.  If a command is being
        !          1807:  *                     processed on the client's behalf, the client
        !          1808:  *                     will not be deleted until the command's result
        !          1809:  *                     is returned.
        !          1810:  *             $client do ?args?
        !          1811:  *                     Concatenate the client's command with ?args?,
        !          1812:  *                     and execute the result.  Called in background
        !          1813:  *                     when a command arrives and on initial
        !          1814:  *                     connection.
        !          1815:  *             $client hostname
        !          1816:  *                     Returns the name of the host where the client
        !          1817:  *                     is running.
        !          1818:  *             $client server
        !          1819:  *                     Returns the name of the server to which the client
        !          1820:  *                     is connected.
        !          1821:  */
        !          1822: 
        !          1823: static int
        !          1824: tcpClientObjectCmd (clientData, interp, argc, argv)
        !          1825:      ClientData clientData;
        !          1826:      Tcl_Interp * interp;
        !          1827:      int argc;
        !          1828:      char * * argv;
        !          1829: {
        !          1830:   int c;
        !          1831:   unsigned length;
        !          1832: 
        !          1833:   if (argc < 2) {
        !          1834:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [0],
        !          1835:                      " command ?args?\"", (char *) NULL);
        !          1836:     return TCL_ERROR;
        !          1837:   }
        !          1838: 
        !          1839:   c = argv [1] [0];
        !          1840:   length = strlen (argv [1]);
        !          1841:   
        !          1842:   if (c == 'c' && length >= 2 && strncmp (argv [1], "close", length) == 0) {
        !          1843:     return tcpClientObjectCloseCmd (clientData, interp, argc-1, argv+1);
        !          1844:   }
        !          1845:   if (c == 'c' && length >= 2 && strncmp (argv [1], "command", length) == 0) {
        !          1846:     return tcpClientObjectCommandCmd (clientData, interp, argc-1, argv+1);
        !          1847:   }
        !          1848:   if (c == 'd' && strncmp (argv [1], "do", length) == 0) {
        !          1849:     return tcpClientObjectDoCmd (clientData, interp, argc-1, argv+1);
        !          1850:   }
        !          1851:   if (c == 'h' && strncmp (argv [1], "hostname", length) == 0) {
        !          1852:     return tcpClientObjectHostnameCmd (clientData, interp, argc-1, argv+1);
        !          1853:   }
        !          1854:   if (c == 's' && strncmp (argv [1], "server", length) == 0) {
        !          1855:     return tcpClientObjectServerCmd (clientData, interp, argc-1, argv+1);
        !          1856:   }
        !          1857: 
        !          1858:   Tcl_AppendResult (interp, "bad option \"", argv [1],
        !          1859:                    "\": should be close, command, do, hostname or server",
        !          1860:                    (char *) NULL);
        !          1861:   return TCL_ERROR;
        !          1862: }
        !          1863: 
        !          1864: /* 
        !          1865:  * tcpClientObjectCloseCmd --
        !          1866:  *
        !          1867:  *     This procedure is called when the Tcl program wants to close a client.
        !          1868:  * If the client is active, it sets a flag to close the client when it
        !          1869:  * becomes quiescent.  Otherwise, it closes the client immediately.
        !          1870:  */
        !          1871: 
        !          1872: static int
        !          1873: tcpClientObjectCloseCmd (clientData, interp, argc, argv)
        !          1874:      ClientData clientData;
        !          1875:      Tcl_Interp * interp;
        !          1876:      int argc;
        !          1877:      char * * argv;
        !          1878: {
        !          1879:   register Tcp_ClientData * client = (Tcp_ClientData *) clientData;
        !          1880: 
        !          1881:   if (argc != 1) {
        !          1882:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1], " ",
        !          1883:                      argv [0], "\"", (char *) NULL);
        !          1884:     return TCL_ERROR;
        !          1885:   }
        !          1886: 
        !          1887:   if (client -> activeFlag)
        !          1888:     client -> closeFlag = 1;
        !          1889:   else
        !          1890:     tcpCloseClient (client);
        !          1891: 
        !          1892:   return TCL_OK;
        !          1893: }
        !          1894: 
        !          1895: /* 
        !          1896:  * tcpClientObjectCommandCmd --
        !          1897:  *
        !          1898:  *     Query/change the command associated with a client object
        !          1899:  *
        !          1900:  * Syntax:
        !          1901:  *     $client command ?newcommand?
        !          1902:  *
        !          1903:  * Return:
        !          1904:  *     A standard Tcl result containing the client's command.
        !          1905:  */
        !          1906: 
        !          1907: static int
        !          1908: tcpClientObjectCommandCmd (clientData, interp, argc, argv)
        !          1909:      ClientData clientData;
        !          1910:      Tcl_Interp * interp;
        !          1911:      int argc;
        !          1912:      char * * argv;
        !          1913: {
        !          1914:   register Tcp_ClientData * client = (Tcp_ClientData *) clientData;
        !          1915: 
        !          1916:   /* Check syntax */
        !          1917: 
        !          1918:   if (argc > 2) {
        !          1919:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1], " ",
        !          1920:                      argv [0], " ?command?\"", (char *) NULL);
        !          1921:     return TCL_ERROR;
        !          1922:   }
        !          1923: 
        !          1924:   /* Set command if necessary */
        !          1925: 
        !          1926:   if (argc == 2) {
        !          1927:     if (client -> freeCommand != (Tcl_FreeProc *) NULL) {
        !          1928:       (*client -> freeCommand) (client -> command);
        !          1929:     }
        !          1930:     client -> command = malloc (strlen (argv [1]) + 1);
        !          1931:     strcpy (client -> command, argv [1]);
        !          1932:     client -> freeCommand = (Tcl_FreeProc *) free;
        !          1933:   }
        !          1934: 
        !          1935:   /* Return command in any case */
        !          1936: 
        !          1937:   Tcl_SetResult (interp, client -> command, TCL_STATIC);
        !          1938: 
        !          1939:   return TCL_OK;
        !          1940: }
        !          1941: 
        !          1942: /*
        !          1943:  * tcpClientObjectDoCmd --
        !          1944:  *
        !          1945:  *     The following procedure handles the `do' command on a client
        !          1946:  *     object.  It is called
        !          1947:  *             (a) as "$client do", at login.
        !          1948:  *             (b) as "$client do <command>", when the client sends a
        !          1949:  *                     command. 
        !          1950:  *             (c) as "$client do", with no further arguments, when
        !          1951:  *                     the connection is closed.
        !          1952:  *     It concatenates the client's saved command string with the
        !          1953:  *     client's name, and then with the passed command, resulting in
        !          1954:  *     a command:
        !          1955:  *             saved_command client passed_command
        !          1956:  *     which is then passed to Tcl_Eval for processing.
        !          1957:  *      During the processing of the command, the `active' flag is set for
        !          1958:  *     the client, to avoid having the client closed prematurely.
        !          1959:  */
        !          1960: static int
        !          1961: tcpClientObjectDoCmd (clientData, interp, argc, argv)
        !          1962:      ClientData clientData;
        !          1963:      Tcl_Interp * interp;
        !          1964:      int argc;
        !          1965:      char * * argv;
        !          1966: {
        !          1967: 
        !          1968:   register Tcp_ClientData * client = (Tcp_ClientData *) clientData;
        !          1969:   int status;
        !          1970:   int closeflag;
        !          1971:   char * prevClient;
        !          1972:   char * excmd;
        !          1973:   unsigned excmdl;
        !          1974:   int scanflags;
        !          1975: 
        !          1976:   /* Check command syntax */
        !          1977: 
        !          1978:   if (argc > 2) {
        !          1979:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1],
        !          1980:                      " ", argv [0], " ?command?\"", (char *) NULL);
        !          1981:     return TCL_ERROR;
        !          1982:   }
        !          1983: 
        !          1984:   prevClient = tcpCurrentClient;
        !          1985:   tcpCurrentClient = client -> name;
        !          1986: 
        !          1987:   /* Evaluate the client's command, passing the client name and message */
        !          1988: 
        !          1989:   closeflag = 0;
        !          1990:   client -> activeFlag = 1;
        !          1991: 
        !          1992:   if (argc == 2) {
        !          1993:     excmdl = Tcl_ScanElement (argv [1], &scanflags) + 1;
        !          1994:     excmd = (char *) ckalloc (excmdl);
        !          1995:     excmdl = Tcl_ConvertElement (argv [1], excmd, scanflags);
        !          1996:     excmd [excmdl] = '\0';
        !          1997:   } else {
        !          1998:     excmd = (char *) NULL;
        !          1999:   }
        !          2000: 
        !          2001:   status = Tcl_VarEval (interp, client -> command, " ", client -> name, " ",
        !          2002:                        excmd, (char *) NULL);
        !          2003: 
        !          2004:   if (excmd)
        !          2005:     ckfree (excmd);
        !          2006:   
        !          2007:   if (status != TCL_OK && argc < 2) {
        !          2008:     closeflag = 1;
        !          2009:   }
        !          2010: 
        !          2011:   client -> activeFlag = 0;
        !          2012:   tcpCurrentClient = prevClient;
        !          2013: 
        !          2014:   /* If the client command throws an error on login or logout,
        !          2015:    * the client should be disconnected.
        !          2016:    * In any case, the result should be reported back to the client.
        !          2017:    */
        !          2018: 
        !          2019:   if (! (client -> server -> raw)) {
        !          2020:     tcpReturnResultToClient (client, interp, status, closeflag);
        !          2021:   } else {
        !          2022:     tcpPrepareClientForInput (client);
        !          2023:   }
        !          2024: 
        !          2025:   /* The client may have been closed by the ReturnResult operation. DON'T
        !          2026:    * USE IT AFTER THIS POINT.
        !          2027:    */
        !          2028: 
        !          2029:   return TCL_OK;
        !          2030: }
        !          2031: 
        !          2032: /*
        !          2033:  * tcpClientObjectHostnameCmd --
        !          2034:  *
        !          2035:  *     This procedure is invoked in response to the `$client hostname'
        !          2036:  * Tcl command.  It returns the name of the peer host on which the client
        !          2037:  * runs.
        !          2038:  */
        !          2039: 
        !          2040: static int
        !          2041: tcpClientObjectHostnameCmd (clientData, interp, argc, argv)
        !          2042:      ClientData clientData;
        !          2043:      Tcl_Interp * interp;
        !          2044:      int argc;
        !          2045:      char * * argv;
        !          2046: {
        !          2047:   register Tcp_ClientData * client = (Tcp_ClientData *) clientData;
        !          2048: 
        !          2049:   struct hostent * hostdesc;
        !          2050: 
        !          2051:   if (argc != 1) {
        !          2052:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1], " ",
        !          2053:                      argv [0], "\"", (char *) NULL);
        !          2054:     return TCL_ERROR;
        !          2055:   }
        !          2056: 
        !          2057:   hostdesc = gethostbyaddr ((char *) &(client -> peeraddr.sin_addr.s_addr),
        !          2058:                            sizeof (client -> peeraddr.sin_addr.s_addr),
        !          2059:                            AF_INET);
        !          2060:   
        !          2061:   if (hostdesc != (struct hostent *) NULL) {
        !          2062:     Tcl_SetResult (interp, hostdesc -> h_name, TCL_VOLATILE);
        !          2063:   } else {
        !          2064:     Tcl_SetResult (interp, inet_ntoa (client -> peeraddr.sin_addr),
        !          2065:                   TCL_VOLATILE);
        !          2066:   }
        !          2067: 
        !          2068:   return TCL_OK;
        !          2069: }
        !          2070: 
        !          2071: /*
        !          2072:  * tcpClientObjectServerCmd --
        !          2073:  *
        !          2074:  *     This procedure is invoked in response to the `$client server'
        !          2075:  * Tcl command.  It returns the name of the server to which the client
        !          2076:  * is connected.
        !          2077:  */
        !          2078: 
        !          2079: static int
        !          2080: tcpClientObjectServerCmd (clientData, interp, argc, argv)
        !          2081:      ClientData clientData;
        !          2082:      Tcl_Interp * interp;
        !          2083:      int argc;
        !          2084:      char * * argv;
        !          2085: {
        !          2086:   register Tcp_ClientData * client = (Tcp_ClientData *) clientData;
        !          2087: 
        !          2088:   if (argc != 1) {
        !          2089:     Tcl_AppendResult (interp, "wrong # args: should be \"", argv [-1], " ",
        !          2090:                      argv [0], "\"", (char *) NULL);
        !          2091:     return TCL_ERROR;
        !          2092:   }
        !          2093: 
        !          2094:   Tcl_SetResult (interp, client -> server -> name, TCL_STATIC);
        !          2095: 
        !          2096:   return TCL_OK;
        !          2097: }
        !          2098: 
        !          2099: /*
        !          2100:  * deleteTcpClientObjectCmd --
        !          2101:  *
        !          2102:  *     This procedure is invoked when a client object's command has
        !          2103:  * been deleted.  WARNING -- deleting a client object command when the
        !          2104:  * client is active is a FATAL error that cannot be reported through the
        !          2105:  * Tcl interpreter.
        !          2106:  *
        !          2107:  *     This procedure does all the cleanup necessary to getting rid of the
        !          2108:  * client.
        !          2109:  */
        !          2110: 
        !          2111: static void
        !          2112: deleteTcpClientObjectCmd (clientData)
        !          2113:      ClientData clientData;
        !          2114: {
        !          2115:   register Tcp_ClientData * client = (Tcp_ClientData *) clientData;
        !          2116:   register Tcp_ServerData * server = client -> server;
        !          2117: 
        !          2118:   /* Make sure the client is really dead. */
        !          2119: 
        !          2120:   if (client -> activeFlag) {
        !          2121:     fprintf (stderr, "attempt to delete an active TCP client!\n\n");
        !          2122:     abort ();
        !          2123:   }
        !          2124: 
        !          2125:   /* Remove any handler for data on the client's socket. */
        !          2126: 
        !          2127:   simpleDeleteFileHandler (client -> socketfd);
        !          2128: 
        !          2129:   /* Now it's safe to close the socket */
        !          2130: 
        !          2131:   (void) close (client -> socketfd);
        !          2132: 
        !          2133:   /* Get rid of the command */
        !          2134: 
        !          2135:   if (client -> command != NULL && client -> freeCommand != NULL) {
        !          2136:     (*(client -> freeCommand)) (client -> command);
        !          2137:   }
        !          2138: 
        !          2139:   /* Get rid of the input buffer */
        !          2140: 
        !          2141:   Tcl_DeleteCmdBuf (client -> inputBuffer);
        !          2142: 
        !          2143:   /* Get rid of any pending result */
        !          2144: 
        !          2145:   if (client -> resultString != NULL && client -> freeResultString != NULL) {
        !          2146:     (*(client -> freeResultString)) (client -> resultString);
        !          2147:   }
        !          2148: 
        !          2149:   /* Unlink the client from the list of active clients */
        !          2150: 
        !          2151:   if (client -> prev == NULL)
        !          2152:     client -> server -> firstClient = client -> next;
        !          2153:   else
        !          2154:     client -> prev -> next = client -> next;
        !          2155: 
        !          2156:   if (client -> next != NULL)
        !          2157:     client -> next -> prev = client -> prev;
        !          2158: 
        !          2159:   /* Now it's ok to destroy the client's data structure */
        !          2160: 
        !          2161:   ckfree ((char *) client);
        !          2162: 
        !          2163:   /* Handle a deferred close on the server if necessary */
        !          2164: 
        !          2165:   if (server -> stopFlag && server -> firstClient == NULL)
        !          2166:     tcpDeleteServer (server);
        !          2167: }
        !          2168: 
        !          2169: /*
        !          2170:  * tcpConnectionObjectCmd --
        !          2171:  *
        !          2172:  *     This procedure is invoked to process the object command for a client-
        !          2173:  * side connection object.  It takes a couple of diferent forms:
        !          2174:  *
        !          2175:  *     $connection close
        !          2176:  *             Closes the connection.
        !          2177:  *     $connection send arg ?arg....?
        !          2178:  *             Catenates the arguments into a Tcl command, and sends them
        !          2179:  *             to the server.
        !          2180:  */
        !          2181: 
        !          2182: static int
        !          2183: tcpConnectionObjectCmd (clientData, interp, argc, argv)
        !          2184:      ClientData clientData;
        !          2185:      Tcl_Interp * interp;
        !          2186:      int argc;
        !          2187:      char * * argv;
        !          2188: {
        !          2189:   unsigned length;
        !          2190:   int c;
        !          2191:   char * arg;
        !          2192: 
        !          2193:   if (argc < 2) {
        !          2194:     Tcl_AppendResult (interp, "wrong # args, should be \"", argv [0], " ",
        !          2195:                      "command ?args?\"", (char *) NULL);
        !          2196:     return TCL_ERROR;
        !          2197:   }
        !          2198: 
        !          2199:   arg = argv [1];
        !          2200:   c = arg [0];
        !          2201:   length = strlen (arg);
        !          2202: 
        !          2203:   if (c == 'c' && strncmp (arg, "close", length) == 0) {
        !          2204:     return tcpConnectionObjectCloseCmd (clientData, interp, argc-1, argv+1);
        !          2205:   }
        !          2206:   if (c == 's' && strncmp (arg, "send", length) == 0) {
        !          2207:     return tcpConnectionObjectSendCmd (clientData, interp, argc-1, argv+1);
        !          2208:   }
        !          2209: 
        !          2210:   Tcl_AppendResult (interp, "unknown command \"", arg,
        !          2211:                    "\": must be close or send", (char *) NULL);
        !          2212:   return TCL_ERROR;
        !          2213: }
        !          2214: 
        !          2215: /*
        !          2216:  * tcpConnectionObjectCloseCmd --
        !          2217:  *
        !          2218:  *     This procedure is invoked in response to a `close' command on a
        !          2219:  * client-side connection object.  It closes the socket and deletes the
        !          2220:  * object command.
        !          2221:  */
        !          2222: 
        !          2223: /* ARGSUSED */
        !          2224: static int
        !          2225: tcpConnectionObjectCloseCmd (clientData, interp, argc, argv)
        !          2226:      ClientData clientData;
        !          2227:      Tcl_Interp * interp;
        !          2228:      int argc;
        !          2229:      char * * argv;
        !          2230: {
        !          2231:   if (argc != 1) {
        !          2232:     Tcl_AppendResult (interp, "wrong # args, should be \"", argv [-1], " ",
        !          2233:                      argv [0], "\"", (char *) NULL);
        !          2234:     return TCL_ERROR;
        !          2235:   }
        !          2236: 
        !          2237:   Tcl_DeleteCommand (interp, argv [-1]);
        !          2238:   return TCL_OK;
        !          2239: }
        !          2240: 
        !          2241: /*
        !          2242:  * tcpConnectionObjectSendCmd --
        !          2243:  *
        !          2244:  *     This procedure is invoked in response to a `send' command on a client-
        !          2245:  * side connection object.  It catenates the `send' arguments into a single
        !          2246:  * string, presents that string to the server as a command, and returns the
        !          2247:  * server's reply.
        !          2248:  */
        !          2249: 
        !          2250: static int
        !          2251: tcpConnectionObjectSendCmd (clientData, interp, argc, argv)
        !          2252:      ClientData clientData;
        !          2253:      Tcl_Interp * interp;
        !          2254:      int argc;
        !          2255:      char * * argv;
        !          2256: {
        !          2257:   char * message;
        !          2258:   int f = (int) clientData;
        !          2259:   int status;
        !          2260: 
        !          2261:   if (argc < 2) {
        !          2262:     Tcl_AppendResult (interp, "wrong # args, should be \"", argv [-1], " ",
        !          2263:                      argv [0], " command\"", (char *) NULL);
        !          2264:     return TCL_ERROR;
        !          2265:   }
        !          2266: 
        !          2267:   /* Paste together the message */
        !          2268: 
        !          2269:   message = Tcl_Merge (argc-1, argv+1);
        !          2270: 
        !          2271:   /* Send the command to the server */
        !          2272: 
        !          2273:   status = tcpSendCmdToServer (interp, f, message);
        !          2274:   if (status != TCL_OK)
        !          2275:     return status;
        !          2276: 
        !          2277:   /* Get the server's reply */
        !          2278: 
        !          2279:   return tcpReceiveResultFromServer (interp, f);
        !          2280: }
        !          2281: 
        !          2282: /*
        !          2283:  * deleteTcpConnectionObjectCmd --
        !          2284:  *
        !          2285:  *     This procedure is called when a connection object is to be
        !          2286:  * deleted.  It just has to close the socket that the object uses.
        !          2287:  */
        !          2288: 
        !          2289: static void
        !          2290: deleteTcpConnectionObjectCmd (clientData)
        !          2291:      ClientData clientData;
        !          2292: {
        !          2293:   int f = (int) clientData;
        !          2294:   (void) close (f);
        !          2295: }
        !          2296: 
        !          2297: /*
        !          2298:  * tcpCloseClient --
        !          2299:  *
        !          2300:  *     This procedure is called when the program is completely done with
        !          2301:  * a client object.  If the `active' flag is set, there is still a reference
        !          2302:  * to the dead client, but we shouldn't have come here in that case.
        !          2303:  */
        !          2304: 
        !          2305: static void
        !          2306: tcpCloseClient (client)
        !          2307:      Tcp_ClientData * client;
        !          2308: {
        !          2309:   if (client -> activeFlag) 
        !          2310:     abort ();
        !          2311: 
        !          2312:   /* Deleting the client command is all we need to do -- the delete
        !          2313:    * procedure does everything else.
        !          2314:    */
        !          2315: 
        !          2316:   Tcl_DeleteCommand (client -> server -> interp, client -> name);
        !          2317: }
        !          2318: 
        !          2319: /*
        !          2320:  * tcpServerAcceptConnection --
        !          2321:  *
        !          2322:  *     This procedure is invoked as a file handler whenever a server's
        !          2323:  *     socket is ready for `reading' -- i.e., has a connection request
        !          2324:  *     outstanding.
        !          2325:  *
        !          2326:  *     It calls the `accept' command on the server to create a client.
        !          2327:  *     If the `accept' is successful, it then calls the `do'
        !          2328:  *     command on the client.  If either call fails, a background error
        !          2329:  *     is reported.
        !          2330:  */
        !          2331: 
        !          2332: /* ARGSUSED */
        !          2333: static void
        !          2334: tcpServerAcceptConnection (clientData, mask)
        !          2335:      ClientData clientData;
        !          2336:      int mask;
        !          2337: {
        !          2338:   register Tcp_ServerData * server = (Tcp_ServerData *) clientData;
        !          2339: 
        !          2340:   int status;
        !          2341: 
        !          2342:   char * clientName;
        !          2343: 
        !          2344:   /* Accept the connection with `$server accept' */
        !          2345: 
        !          2346:   status = Tcl_VarEval (server -> interp, server -> name, " accept",
        !          2347:                     (char *) NULL);
        !          2348: 
        !          2349:   /* On success, try to execute the client's command with `$client do' */
        !          2350: 
        !          2351:   if (status == TCL_OK) {
        !          2352:     clientName = (char *) ckalloc (strlen (server -> interp -> result) + 1);
        !          2353:     strcpy (clientName, server -> interp -> result);
        !          2354:     status = Tcl_VarEval (server -> interp, clientName, " do", (char *) NULL);
        !          2355: 
        !          2356:     /* Client may have been closed at this point.  Don't refer to it again. */
        !          2357:   }
        !          2358: 
        !          2359:   if (status != TCL_OK) {
        !          2360:     simpleReportBackgroundError (server -> interp);
        !          2361:   }
        !          2362:   Tcl_ResetResult (server -> interp);
        !          2363: }
        !          2364: 
        !          2365: /*
        !          2366:  * tcpTrustedHost --
        !          2367:  *
        !          2368:  *     This procedure is invoked whenever the code must determine whether
        !          2369:  * a host is trusted.  A host is considered trusted only if it is the local
        !          2370:  * host.
        !          2371:  *
        !          2372:  * Results:
        !          2373:  *     Returns a Boolean value that is TRUE iff the host is trusted.
        !          2374:  */
        !          2375: 
        !          2376: /* The HOSTCMP macro is just strcmp, but puts its args on stderr if
        !          2377:  * the DEBUG_TRUSTED_HOST flag is #define'd.  It's used because this
        !          2378:  * code can be a little flaky; if `hostname' returns a name that is
        !          2379:  * completely unknown in the database, this macro will trace what happened.
        !          2380:  */
        !          2381: 
        !          2382: #ifdef DEBUG_TRUSTED_HOST
        !          2383: #define HOSTCMP( name1, name2 )                                        \
        !          2384:   (fprintf (stderr, "tcpTrustedHost: comparing %s with %s\n",  \
        !          2385:            (name1), (name2)),                                  \
        !          2386:    strcmp ((name1), (name2)))
        !          2387: #else
        !          2388: #define HOSTCMP( name1, name2 )                                        \
        !          2389:   strcmp ((name1), (name2))
        !          2390: #endif
        !          2391: 
        !          2392: static int
        !          2393: tcpTrustedHost (hostName)
        !          2394:      char * hostName;
        !          2395: {
        !          2396:   char localName [128];
        !          2397:   struct hostent * hostEnt;
        !          2398:   struct in_addr hostAddr;
        !          2399:   int unixStatus;
        !          2400:   int i;
        !          2401: 
        !          2402:   /* This procedure really has to do things the hard way.  The problem is
        !          2403:    * that the hostname() kernel call returns the host name set by the system
        !          2404:    * administrator, which may not be the host's primary name as known to
        !          2405:    * the domain name system.  Furthermore, the host presented may be one
        !          2406:    * of the names for the loopback port, 127.0.0.1, and this must be checked,
        !          2407:    * too.
        !          2408:    */
        !          2409: 
        !          2410:   /* Start assembling a list of possibilities for the host name.  First
        !          2411:    * possibility is the name that the kernel returns as hostname ().
        !          2412:    */
        !          2413: 
        !          2414:   unixStatus = gethostname (localName, 127);
        !          2415:   if (unixStatus >= 0) {
        !          2416: 
        !          2417:     if (!HOSTCMP( hostName, localName )) return 1;
        !          2418: 
        !          2419:     /* Next possibility is a.b.c.d notation for all of the local addresses,
        !          2420:      * plus all the nicknames for the host. 
        !          2421:      */
        !          2422: 
        !          2423:     hostEnt = gethostbyname (localName);
        !          2424:     if (hostEnt != (struct hostent *) NULL) {
        !          2425:       if (!HOSTCMP( hostName, hostEnt -> h_name )) return 1;
        !          2426:       if (hostEnt -> h_aliases != (char * *) NULL) {
        !          2427:        for (i = 0; hostEnt -> h_aliases [i] != (char *) NULL; ++i) {
        !          2428:          if (!HOSTCMP( hostName, hostEnt -> h_aliases [i] )) return 1;
        !          2429:        }
        !          2430:       }
        !          2431:       if (hostEnt -> h_addr_list != (char * *) NULL) {
        !          2432:        for (i = 0; hostEnt -> h_addr_list [i] != (char *) NULL; ++i) {
        !          2433:          /* note that the address doesn't have to be word-aligned (!) */
        !          2434:          memcpy ((char *) &hostAddr,
        !          2435:                  hostEnt -> h_addr_list [i],
        !          2436:                  hostEnt -> h_length);
        !          2437:          if (!HOSTCMP( hostName, inet_ntoa (hostAddr) )) return 1;
        !          2438:        }
        !          2439:       }
        !          2440:     }
        !          2441:   }
        !          2442: 
        !          2443:   /* Finally, there's the possibility of the loopback address, and all of 
        !          2444:    * its aliases.*/
        !          2445: 
        !          2446:   if (!HOSTCMP( hostName, "0.0.0.0" )) return 1;
        !          2447:   if (!HOSTCMP( hostName, "127.0.0.1" )) return 1;
        !          2448:   hostAddr.s_addr = htonl (INADDR_LOOPBACK);
        !          2449:   hostEnt = gethostbyaddr ((char *) &hostAddr, sizeof hostAddr, AF_INET);
        !          2450:   if (hostEnt != (struct hostent *) NULL) {
        !          2451:     if (!HOSTCMP( hostName, hostEnt -> h_name )) return 1;
        !          2452:     if (hostEnt -> h_aliases != (char * *) NULL) {
        !          2453:       for (i = 0; hostEnt -> h_aliases [i] != (char *) NULL; ++i) {
        !          2454:        if (!HOSTCMP( hostName, hostEnt -> h_aliases [i] )) return 1;
        !          2455:       }
        !          2456:     }
        !          2457:     if (hostEnt -> h_addr_list != (char * *) NULL) {
        !          2458:       for (i = 0; hostEnt -> h_addr_list [i] != (char *) NULL; ++i) {
        !          2459:        /* note that the address doesn't have to be word-aligned (!) */
        !          2460:        memcpy ((char *) &hostAddr,
        !          2461:                hostEnt -> h_addr_list [i],
        !          2462:                hostEnt -> h_length);
        !          2463:        if (!HOSTCMP( hostName, inet_ntoa (hostAddr) )) return 1;
        !          2464:       }
        !          2465:     }
        !          2466:   }
        !          2467: 
        !          2468:   return 0;
        !          2469: }
        !          2470: 
        !          2471: /*
        !          2472:  * tcpReturnResultToClient --
        !          2473:  *
        !          2474:  *     This procedure is invoked to return a result to a client.  It
        !          2475:  * extracts the interpreter's result string, bundles it with the return
        !          2476:  * status, and stores it in the client's `resultString' area.
        !          2477:  *
        !          2478:  *     It then calls tcpWriteResultToClient to try to start sending the
        !          2479:  * result.
        !          2480:  */
        !          2481: 
        !          2482: static void
        !          2483: tcpReturnResultToClient (client, interp, status, closeflag)
        !          2484:      Tcp_ClientData * client;
        !          2485:      Tcl_Interp * interp;
        !          2486:      int status;
        !          2487:      int closeflag;
        !          2488: {
        !          2489:   char * argv [2];
        !          2490:   char rint [16];
        !          2491:   unsigned length;
        !          2492:   char * result;
        !          2493:   
        !          2494:   /* Put together a message comprising the return status and the interpreter
        !          2495:    * result */
        !          2496: 
        !          2497:   sprintf (rint, "%d", status);
        !          2498:   argv [0] = rint;
        !          2499:   argv [1] = interp -> result;
        !          2500:   result = Tcl_Merge (2, argv);
        !          2501:   length = strlen (result);
        !          2502:   client -> resultString = (char *) malloc (length + 2);
        !          2503:   strcpy (client -> resultString, result);
        !          2504:   strcpy (client -> resultString + length, "\n");
        !          2505:   free (result);
        !          2506:   client -> resultPointer = client -> resultString;
        !          2507:   client -> freeResultString = (Tcl_FreeProc *) free;
        !          2508: 
        !          2509:   Tcl_ResetResult (interp);
        !          2510:   client -> closeFlag |= closeflag;
        !          2511:   
        !          2512:   /* Now try to send the reply. */
        !          2513: 
        !          2514:   tcpWriteResultToClient ((ClientData) client, TK_WRITABLE);
        !          2515: 
        !          2516:   /* tcpWriteResultToClient closes the client if it fails; don't depend on
        !          2517:    * having the client still be usable. */
        !          2518: }
        !          2519: 
        !          2520: /*
        !          2521:  * tcpWriteResultToClient --
        !          2522:  *
        !          2523:  *     This procedure is invoked to issue a write on a client socket.
        !          2524:  * It can be called directly by tcpReturnResultToClient, to attempt the
        !          2525:  * initial write of results.  It can also be called as a file handler,
        !          2526:  * to retry a write that was previously blocked.
        !          2527:  */
        !          2528: 
        !          2529: /* ARGSUSED */
        !          2530: static void
        !          2531: tcpWriteResultToClient (clientData, mask)
        !          2532:      ClientData clientData;
        !          2533:      int mask;
        !          2534: {
        !          2535:   register Tcp_ClientData * client = (Tcp_ClientData *) clientData;
        !          2536: 
        !          2537:   int unixStatus;
        !          2538:   int length;
        !          2539: 
        !          2540:   length = strlen (client -> resultPointer);
        !          2541: 
        !          2542:   /* Issue the write */
        !          2543: 
        !          2544:   unixStatus = write (client -> socketfd, client -> resultPointer,
        !          2545:                      length);
        !          2546:   
        !          2547:   /* Test for a total failure */
        !          2548: 
        !          2549:   if (unixStatus < 0) {
        !          2550:     if (errno != EWOULDBLOCK) {
        !          2551:       tcpClientWriteError (client);
        !          2552:       /* tcpClientWriteError closes the client as a side effect.  Don't depend
        !          2553:        * on the client still being there.
        !          2554:        */
        !          2555:       return;
        !          2556:     } else {
        !          2557:       unixStatus = 0;          /* Pretend that EWOULDBLOCK succeeded at
        !          2558:                                 * writing zero characters. */
        !          2559:     }
        !          2560:   }
        !          2561: 
        !          2562:   /* Test for a partial success */
        !          2563: 
        !          2564:   if (unixStatus < length) {
        !          2565:     client -> resultPointer += unixStatus;
        !          2566:     simpleCreateFileHandler (client -> socketfd, TK_WRITABLE,
        !          2567:                             (Tk_FileProc *) tcpWriteResultToClient,
        !          2568:                             clientData);
        !          2569:   }
        !          2570: 
        !          2571:   /* Total success -- prepare the client for the next input */
        !          2572: 
        !          2573:   else {
        !          2574:     if (client -> freeResultString != NULL) {
        !          2575:       (*(client -> freeResultString)) (client -> resultString);
        !          2576:     }
        !          2577:     client -> resultString = client -> resultPointer = (char *) NULL;
        !          2578:     client -> freeResultString = (Tcl_FreeProc *) NULL;
        !          2579:     simpleDeleteFileHandler (client -> socketfd);
        !          2580:     if (client -> closeFlag) {
        !          2581:       tcpCloseClient (client);
        !          2582: 
        !          2583:       /* After tcpCloseClient executes, the client goes away.  Don't depend
        !          2584:         on it's still being there. */
        !          2585: 
        !          2586:     } else {
        !          2587:       tcpPrepareClientForInput (client);
        !          2588:     }
        !          2589:   }
        !          2590: }   
        !          2591: 
        !          2592: /*
        !          2593:  * tcpPrepareClientForInput --
        !          2594:  *
        !          2595:  *     This procedure is invoked to prepare a client to accept command
        !          2596:  * input.  It establishes a handler, tcpReceiveClientInput, that does the
        !          2597:  * actual command buffering.
        !          2598:  */
        !          2599: 
        !          2600: static void
        !          2601: tcpPrepareClientForInput (client)
        !          2602:      Tcp_ClientData * client;
        !          2603: {
        !          2604:   simpleCreateFileHandler (client -> socketfd, TK_READABLE,
        !          2605:                           (Tk_FileProc *) tcpReceiveClientInput,
        !          2606:                           (ClientData) client);
        !          2607: }
        !          2608: 
        !          2609: /*
        !          2610:  * tcpReceiveClientInput --
        !          2611:  *
        !          2612:  *     This procedure is called when a server is awaiting input from a client
        !          2613:  * and the client socket tests to be `ready to read'.  It reads a bufferload
        !          2614:  * of data from the client, and places it in the client's command buffer.  If
        !          2615:  * the command is complete, it then tries to invoke the command.
        !          2616:  */
        !          2617: 
        !          2618: /* ARGSUSED */
        !          2619: static void
        !          2620: tcpReceiveClientInput (clientData, mask)
        !          2621:      ClientData clientData;
        !          2622:      int mask;
        !          2623: {
        !          2624:   register Tcp_ClientData * client = (Tcp_ClientData *) clientData;
        !          2625:   register Tcp_ServerData * server = client -> server;
        !          2626:   register Tcl_Interp * interp = server -> interp;
        !          2627: 
        !          2628:   static char buffer [BUFSIZ+1];
        !          2629:   int unixStatus;
        !          2630:   char * command;
        !          2631:   int status;
        !          2632:   char * docmd;
        !          2633:   char * argv [3];
        !          2634:   int argc;
        !          2635:   int i;
        !          2636: 
        !          2637:   /* Try to read from the client */
        !          2638: 
        !          2639:   errno = 0;
        !          2640:   unixStatus = read (client -> socketfd, buffer, BUFSIZ);
        !          2641:   if (unixStatus <= 0 && errno != EWOULDBLOCK)
        !          2642:     tcpClientReadError (client);
        !          2643: 
        !          2644:   /* tcpClientReadError closes the client and reports the error.
        !          2645:      In any case, if the read failed, we want to return. */
        !          2646: 
        !          2647:   if (unixStatus <= 0)
        !          2648:     return;
        !          2649: 
        !          2650:   if (server -> raw) {
        !          2651:     char buf[512];
        !          2652: 
        !          2653:     sprintf(buf, "RawInput %s %d %d", client -> name, buffer, unixStatus);
        !          2654: printf("TCP executing: %s\n", buf);
        !          2655:     status = Tcl_Eval (interp, buf, 0, (char * *) NULL);
        !          2656: 
        !          2657:     tcpPrepareClientForInput (client);
        !          2658: 
        !          2659:   } else {
        !          2660: 
        !          2661:     /* Assemble the received data into the buffer */
        !          2662: 
        !          2663:     buffer [unixStatus] = '\0';
        !          2664:     command = Tcl_AssembleCmd (client -> inputBuffer, buffer);
        !          2665:     if (command != (char *) NULL) {
        !          2666: 
        !          2667:       /* Process the received command. */
        !          2668: 
        !          2669:       simpleDeleteFileHandler (client -> socketfd);
        !          2670:       argc = 3;
        !          2671:       argv [0] = client -> name;
        !          2672:       argv [1] = "do";
        !          2673:       argv [2] = command;
        !          2674:       docmd = Tcl_Merge (argc, argv);
        !          2675:       status = Tcl_Eval (interp, docmd, 0, (char * *) NULL);
        !          2676:       free (docmd);
        !          2677: 
        !          2678:       /* At this point, the client may have been closed.  Don't try to
        !          2679:         refer to it. */
        !          2680: 
        !          2681:       if (status != TCL_OK) {
        !          2682:        simpleReportBackgroundError (interp);
        !          2683:       }
        !          2684:     }
        !          2685:   }
        !          2686: }
        !          2687: 
        !          2688: /* tcpClientReadError --
        !          2689:  *
        !          2690:  *     This procedure is called when an attempt to read the command from a
        !          2691:  * client fails.  There are two possibilities:
        !          2692:  *
        !          2693:  *     The first is that there really was a read error, originating in the
        !          2694:  * socket system.  In this case, the error should be reported at background
        !          2695:  * level, and the client should be closed.
        !          2696:  *
        !          2697:  *     The second is that the read reached the end-of-information marker in
        !          2698:  * the client's stream.  In this case, the `do' command should be called on
        !          2699:  * the client one last time, and then the client should be closed.
        !          2700:  *
        !          2701:  *     If the application needs to clean the client up after a read error,
        !          2702:  * it must define the `tcperror' procedure and process the error.
        !          2703:  */
        !          2704: 
        !          2705: static void
        !          2706: tcpClientReadError (client)
        !          2707:      Tcp_ClientData * client;
        !          2708: {
        !          2709:   Tcp_ServerData * server = client -> server;
        !          2710:   Tcl_Interp * interp = server -> interp;
        !          2711:   int status;
        !          2712: 
        !          2713:   if (errno != 0) {
        !          2714: 
        !          2715:     /* Read error */
        !          2716: 
        !          2717:     status = Tcl_VarEval (interp, "error {", client -> name, ": read error: ",
        !          2718:                          Tcl_UnixError (interp), "}", (char *) NULL);
        !          2719:     simpleReportBackgroundError (interp);
        !          2720:     
        !          2721:   } else {
        !          2722: 
        !          2723:     /* End of file */
        !          2724: 
        !          2725:     status = Tcl_VarEval (interp, client -> name, " do", (char *) NULL);
        !          2726:     if (status != TCL_OK)
        !          2727:       simpleReportBackgroundError (interp);
        !          2728:   }
        !          2729: 
        !          2730:   tcpCloseClient (client);
        !          2731: }
        !          2732: 
        !          2733: /* tcpClientWriteError --
        !          2734:  *
        !          2735:  *     This procedure is invoked when an attempt to return results to a client
        !          2736:  * has failed.  It reports the error at background level and closes the client.
        !          2737:  *
        !          2738:  *     If the application needs to clean up the client after a write error,
        !          2739:  * it must define the `tcperror' procedure to catch the error.
        !          2740:  */
        !          2741: 
        !          2742: static void
        !          2743: tcpClientWriteError (client)
        !          2744:      Tcp_ClientData * client;
        !          2745: {
        !          2746:   Tcp_ServerData * server = client -> server;
        !          2747:   Tcl_Interp * interp = server -> interp;
        !          2748: 
        !          2749:   (void) Tcl_VarEval (interp, "error {", client -> name, ": read error: ",
        !          2750:                        Tcl_UnixError (interp), "}", (char *) NULL);
        !          2751:   simpleReportBackgroundError (interp);
        !          2752:   tcpCloseClient (client);
        !          2753: }
        !          2754: 
        !          2755: /* tcpSendCmdToServer --
        !          2756:  *
        !          2757:  *     This procedure is invoked to send a command originated by a client
        !          2758:  * using the `$connection send' Tcl command.
        !          2759:  *
        !          2760:  *     The message is passed without a newline appended.  The server requires
        !          2761:  * a newline, which is sent in a separate call.
        !          2762:  */
        !          2763: 
        !          2764: static int
        !          2765: tcpSendCmdToServer (interp, s, message)
        !          2766:      Tcl_Interp * interp;
        !          2767:      int s;
        !          2768:      char * message;
        !          2769: {
        !          2770:   int length;
        !          2771:   int unixStatus;
        !          2772:   int rubbish;
        !          2773:   static char newline = '\n';
        !          2774:   void (*oldPipeHandler) ();
        !          2775: 
        !          2776:   /* Set the socket for blocking I/O */
        !          2777: 
        !          2778:   rubbish = 0;
        !          2779:   unixStatus = ioctl (s, FIONBIO, (char *) &rubbish);
        !          2780:   if (unixStatus < 0) {
        !          2781:     Tcl_AppendResult (interp, "can't set blocking I/O on socket: ",
        !          2782:                      Tcl_UnixError (interp), (char *) NULL);
        !          2783:     return TCL_ERROR;
        !          2784:   }
        !          2785: 
        !          2786:   /* Keep a possible broken pipe from killing us silently */
        !          2787: 
        !          2788:   oldPipeHandler = signal (SIGPIPE, SIG_IGN);
        !          2789: 
        !          2790:   /* Write the message */
        !          2791:   
        !          2792:   length = strlen (message);
        !          2793:   unixStatus = write (s, message, length);
        !          2794:   if (unixStatus < length) {
        !          2795:     (void) signal (SIGPIPE, oldPipeHandler);
        !          2796:     Tcl_AppendResult (interp, "can't send message to server: ",
        !          2797:                      Tcl_UnixError (interp), (char *) NULL);
        !          2798:     return TCL_ERROR;
        !          2799:   }
        !          2800: 
        !          2801:   /* Write the terminating newline */
        !          2802: 
        !          2803:   unixStatus = write (s, &newline, 1);
        !          2804:   if (unixStatus < 1) {
        !          2805:     (void) signal (SIGPIPE, oldPipeHandler);
        !          2806:     Tcl_AppendResult (interp, "can't send newline to server: ",
        !          2807:                      Tcl_UnixError (interp), (char *) NULL);
        !          2808:     return TCL_ERROR;
        !          2809:   }
        !          2810: 
        !          2811:   (void) signal (SIGPIPE, oldPipeHandler);
        !          2812:   return TCL_OK;
        !          2813: }
        !          2814: 
        !          2815: /*
        !          2816:  * tcpReceiveResultFromServer --
        !          2817:  *
        !          2818:  *     This procedure is invoked to get the result transmitted from
        !          2819:  * a remote server, either on establishing the connection or on processing
        !          2820:  * a command.  It returns a standard Tcl result that is usually the result
        !          2821:  * returned by the server.
        !          2822:  */
        !          2823: 
        !          2824: static int
        !          2825: tcpReceiveResultFromServer (interp, s)
        !          2826:      Tcl_Interp * interp;
        !          2827:      int s;
        !          2828: {
        !          2829:   int status;
        !          2830:   int unixStatus;
        !          2831:   int junk;
        !          2832:   Tcl_CmdBuf cmdbuf;
        !          2833:   struct timeval tick;
        !          2834:   struct timeval * tickp;
        !          2835:   fd_set readfds;
        !          2836:   char buf [BUFSIZ+1];
        !          2837:   char * reply;
        !          2838:   int rargc;
        !          2839:   char * * rargv;
        !          2840:   int rstatus;
        !          2841: 
        !          2842:   /* Read the result using non-blocking I/O */
        !          2843: 
        !          2844:   junk = 1;
        !          2845:   unixStatus = ioctl (s, FIONBIO, (char *) &junk);
        !          2846:   if (unixStatus < 0) {
        !          2847:     Tcl_AppendResult (interp, "can't set nonblocking I/O on socket: ",
        !          2848:                      Tcl_UnixError (interp), (char *) NULL);
        !          2849:     return TCL_ERROR;
        !          2850:   }
        !          2851: 
        !          2852:   /* Make a buffer to receive the result */
        !          2853: 
        !          2854:   cmdbuf = Tcl_CreateCmdBuf ();
        !          2855: 
        !          2856:   /* Wait for the result to appear */
        !          2857: 
        !          2858:   tickp = (struct timeval *) 0;
        !          2859:   FD_ZERO( &readfds );
        !          2860:   FD_SET( s, &readfds );
        !          2861:   for ( ; ; ) {
        !          2862: 
        !          2863:     unixStatus = select (s + 1, &readfds, (fd_set *) NULL, (fd_set *) NULL,
        !          2864:                         tickp);
        !          2865: 
        !          2866:     if (unixStatus < 0) {
        !          2867:       status = TCL_ERROR;
        !          2868:       Tcl_AppendResult (interp, "error selecting socket for reply: ",
        !          2869:                        Tcl_UnixError (interp), (char *) NULL);
        !          2870:       break;
        !          2871:     }
        !          2872: 
        !          2873:     if (unixStatus == 0) {
        !          2874:       status = TCL_ERROR;
        !          2875:       Tcl_SetResult (interp, "timed out waiting for server reply", TCL_STATIC);
        !          2876:       break;
        !          2877:     }
        !          2878: 
        !          2879:     /* Read the result */
        !          2880: 
        !          2881:     unixStatus = read (s, buf, BUFSIZ);
        !          2882: 
        !          2883:     if (unixStatus < 0) {
        !          2884:       status = TCL_ERROR;
        !          2885:       Tcl_AppendResult (interp, "error reading server reply: ",
        !          2886:                        Tcl_UnixError (interp), (char *) NULL);
        !          2887:       break;
        !          2888:     }
        !          2889: 
        !          2890:     if (unixStatus == 0) {
        !          2891:       status = TCL_ERROR;
        !          2892:       Tcl_SetResult (interp, "Connection closed.", TCL_STATIC);
        !          2893:       break;
        !          2894:     }
        !          2895: 
        !          2896:     /* Parse the (partial) command */
        !          2897:     
        !          2898:     buf [unixStatus] = '\0';
        !          2899:     reply = Tcl_AssembleCmd (cmdbuf, buf);
        !          2900:     if (reply != NULL) {
        !          2901:       status = TCL_OK;
        !          2902:       break;
        !          2903:     }
        !          2904: 
        !          2905:     /* Partial command not yet complete.  Set timeout for reading the
        !          2906:      * rest of the result. */
        !          2907: 
        !          2908:     tick.tv_sec = 30;
        !          2909:     tick.tv_usec = 0;
        !          2910:     tickp = &tick;
        !          2911:   }
        !          2912: 
        !          2913:   /* When we come here, either the status is TCL_ERROR and the error
        !          2914:    * message is already set, or else the status is TCL_OK and `reply'
        !          2915:    * contains the result that we have to return.  The first element of
        !          2916:    * `reply' has the status, and the second has the result string. */
        !          2917: 
        !          2918:   /* Split the list elements */
        !          2919: 
        !          2920:   if (status == TCL_OK) {
        !          2921:     status = Tcl_SplitList (interp, reply, &rargc, &rargv);
        !          2922:     if (status != TCL_OK) {
        !          2923:       Tcl_SetResult (interp, "server returned malformed list", TCL_STATIC);
        !          2924:       status = TCL_ERROR;
        !          2925:     }
        !          2926:   }
        !          2927: 
        !          2928:   /* Verify the element count */
        !          2929: 
        !          2930:   if (status == TCL_OK) {
        !          2931:     if (rargc != 2) {
        !          2932:       Tcl_SetResult (interp, "server returned malformed list", TCL_STATIC);
        !          2933:       status = TCL_ERROR;
        !          2934:       free ((char *) rargv);
        !          2935:     } else {
        !          2936:       status = Tcl_GetInt (interp, rargv [0], &rstatus);
        !          2937:       if (status != TCL_OK) {
        !          2938:        Tcl_SetResult (interp, "server returned unrecognizable status",
        !          2939:                       TCL_STATIC);
        !          2940:        status = TCL_ERROR;
        !          2941:        free ((char *) rargv);
        !          2942:       }
        !          2943:     }
        !          2944:   }
        !          2945: 
        !          2946:   /* Return the result reported by the server */
        !          2947: 
        !          2948:   if (status == TCL_OK) {
        !          2949:     Tcl_SetResult (interp, rargv [1], TCL_VOLATILE);
        !          2950:     status = rstatus;
        !          2951:     free ((char *) rargv);
        !          2952:   }
        !          2953: 
        !          2954:   Tcl_DeleteCmdBuf (cmdbuf);
        !          2955:   return status;
        !          2956: }

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