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Annotation of 43BSD/contrib/courier/daemon/courierd.c, revision 1.1.1.1

1.1       root        1: #ifndef lint
                      2: static char sccsid[] = "@(#)courierd.c 4.4 (Berkeley) 9/17/85";
                      3: #endif
                      4: 
                      5: /*
                      6:  * Courier program instantiation server
                      7:  *
                      8:  * When a connection is made, it reads the program name as a Courier string.
                      9:  * The directory /usr/new/lib/courier is used as a database of program names;
                     10:  * the executable program must either reside there or have a link there.
                     11:  * The program is spawned with user and group ID equal to that of the
                     12:  * executable file, and must write a single zero byte back to the caller to 
                     13:  * indicate successful instantiation.
                     14:  * If instantiation was unsuccessful, the daemon will write back a null-
                     15:  * terminated error message.
                     16:  */
                     17: #include <sys/types.h>
                     18: #include <sys/socket.h>
                     19: #include <sys/stat.h>
                     20: #include <sys/wait.h>
                     21: 
                     22: #include <netinet/in.h>
                     23: 
                     24: #include <stdio.h>
                     25: #include <signal.h>
                     26: #include <errno.h>
                     27: #include <netdb.h>
                     28: #include <setjmp.h>
                     29: #include <syslog.h>
                     30: 
                     31: #include "../lib/courier.h"
                     32: 
                     33: #define LIBCOURIER "/usr/new/lib/courier"
                     34: 
                     35: jmp_buf        alarmbuf;
                     36: int    catch();
                     37: 
                     38: main(argc, argv)
                     39:        int argc;
                     40:        char **argv;
                     41: {
                     42:        struct sockaddr_in sin;
                     43:        Cardinal n, nbytes;
                     44:        struct stat statbuf;
                     45:        char name[200];
                     46:        int len;
                     47: 
                     48:        len = sizeof (sin);
                     49:        if (getpeername(0, &sin, &len) < 0) {
                     50:                fprintf(stderr, "%s: ", argv[0]), perror("getpeername");
                     51:                _exit(1);
                     52:        }
                     53:        openlog("courier", LOG_ODELAY, LOG_DAEMON);
                     54:        if (chdir(LIBCOURIER)) {
                     55:                syslog(LOG_ERR, "chdir: %s: %m", LIBCOURIER);
                     56:                _exit(2);
                     57:        }
                     58:        setpgrp(0, getpid());
                     59:        signal(SIGHUP, SIG_DFL);
                     60:        signal(SIGINT, SIG_DFL);
                     61:        signal(SIGQUIT, SIG_DFL);
                     62:        signal(SIGALRM, catch);
                     63: 
                     64:        dup2(0, 1);
                     65: 
                     66:        alarm(60);
                     67:        if (setjmp(alarmbuf) == 0)
                     68:                read(0, &n, sizeof(Cardinal));
                     69:        alarm(0);
                     70: 
                     71:        UnpackCardinal(&nbytes, &n);
                     72:        /*
                     73:         * Courier strings are always word-aligned, so if the byte count is odd,
                     74:         * we must also read the padding byte.
                     75:         */
                     76:        read(0, name, nbytes + (nbytes % 2));
                     77:        name[nbytes] = '\0';
                     78: 
                     79:        if (name[0] == '/' || name[0] == '.' || stat(name, &statbuf) != 0)
                     80:                goto bad;
                     81:        setgroups(0, 0);
                     82:        setregid(statbuf.st_gid, statbuf.st_gid);
                     83:        setreuid(statbuf.st_uid, statbuf.st_uid);
                     84:        execl(name, name, 0);
                     85: bad:
                     86:        error("Unknown Courier program.\n");
                     87:        syslog(LOG_ERR, "Unknown Courier program");
                     88:        exit(1);
                     89: }
                     90: 
                     91: /*
                     92:  * Catch alarm clock so read's will timeout.
                     93:  */
                     94: catch()
                     95: {
                     96: 
                     97:        longjmp(alarmbuf, 1);
                     98: }
                     99: 
                    100: /*
                    101:  * Write back a null-terminated error message.
                    102:  */
                    103: error(s)
                    104:        char *s;
                    105: {
                    106:        write(1, s, strlen(s)+1);
                    107: }

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