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Annotation of 43BSDTahoe/etc/talkd/table.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1983 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms are permitted
        !             6:  * provided that the above copyright notice and this paragraph are
        !             7:  * duplicated in all such forms and that any documentation,
        !             8:  * advertising materials, and other materials related to such
        !             9:  * distribution and use acknowledge that the software was developed
        !            10:  * by the University of California, Berkeley.  The name of the
        !            11:  * University may not be used to endorse or promote products derived
        !            12:  * from this software without specific prior written permission.
        !            13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            15:  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            16:  */
        !            17: 
        !            18: #ifndef lint
        !            19: static char sccsid[] = "@(#)table.c    5.5 (Berkeley) 6/18/88";
        !            20: #endif /* not lint */
        !            21: 
        !            22: /*
        !            23:  * Routines to handle insertion, deletion, etc on the table
        !            24:  * of requests kept by the daemon. Nothing fancy here, linear
        !            25:  * search on a double-linked list. A time is kept with each 
        !            26:  * entry so that overly old invitations can be eliminated.
        !            27:  *
        !            28:  * Consider this a mis-guided attempt at modularity
        !            29:  */
        !            30: #include <stdio.h>
        !            31: #include <sys/time.h>
        !            32: #include <syslog.h>
        !            33: #include <sys/param.h>
        !            34: 
        !            35: #include <protocols/talkd.h>
        !            36: 
        !            37: #define MAX_ID 16000   /* << 2^15 so I don't have sign troubles */
        !            38: 
        !            39: #define NIL ((TABLE_ENTRY *)0)
        !            40: 
        !            41: extern int debug;
        !            42: struct timeval tp;
        !            43: struct timezone *txp;
        !            44: 
        !            45: typedef struct table_entry TABLE_ENTRY;
        !            46: 
        !            47: struct table_entry {
        !            48:        CTL_MSG request;
        !            49:        long    time;
        !            50:        TABLE_ENTRY *next;
        !            51:        TABLE_ENTRY *last;
        !            52: };
        !            53: 
        !            54: TABLE_ENTRY *table = NIL;
        !            55: CTL_MSG *find_request();
        !            56: CTL_MSG *find_match();
        !            57: char   *malloc();
        !            58: 
        !            59: /*
        !            60:  * Look in the table for an invitation that matches the current
        !            61:  * request looking for an invitation
        !            62:  */
        !            63: CTL_MSG *
        !            64: find_match(request)
        !            65:        register CTL_MSG *request;
        !            66: {
        !            67:        register TABLE_ENTRY *ptr;
        !            68:        long current_time;
        !            69: 
        !            70:        gettimeofday(&tp, &txp);
        !            71:        current_time = tp.tv_sec;
        !            72:        if (debug)
        !            73:                print_request("find_match", request);
        !            74:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !            75:                if ((ptr->time - current_time) > MAX_LIFE) {
        !            76:                        /* the entry is too old */
        !            77:                        if (debug)
        !            78:                                print_request("deleting expired entry",
        !            79:                                    &ptr->request);
        !            80:                        delete(ptr);
        !            81:                        continue;
        !            82:                }
        !            83:                if (debug)
        !            84:                        print_request("", &ptr->request);
        !            85:                if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
        !            86:                    strcmp(request->r_name, ptr->request.l_name) == 0 &&
        !            87:                     ptr->request.type == LEAVE_INVITE)
        !            88:                        return (&ptr->request);
        !            89:        }
        !            90:        return ((CTL_MSG *)0);
        !            91: }
        !            92: 
        !            93: /*
        !            94:  * Look for an identical request, as opposed to a complimentary
        !            95:  * one as find_match does 
        !            96:  */
        !            97: CTL_MSG *
        !            98: find_request(request)
        !            99:        register CTL_MSG *request;
        !           100: {
        !           101:        register TABLE_ENTRY *ptr;
        !           102:        long current_time;
        !           103: 
        !           104:        gettimeofday(&tp, &txp);
        !           105:        current_time = tp.tv_sec;
        !           106:        /*
        !           107:         * See if this is a repeated message, and check for
        !           108:         * out of date entries in the table while we are it.
        !           109:         */
        !           110:        if (debug)
        !           111:                print_request("find_request", request);
        !           112:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !           113:                if ((ptr->time - current_time) > MAX_LIFE) {
        !           114:                        /* the entry is too old */
        !           115:                        if (debug)
        !           116:                                print_request("deleting expired entry",
        !           117:                                    &ptr->request);
        !           118:                        delete(ptr);
        !           119:                        continue;
        !           120:                }
        !           121:                if (debug)
        !           122:                        print_request("", &ptr->request);
        !           123:                if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
        !           124:                    strcmp(request->l_name, ptr->request.l_name) == 0 &&
        !           125:                    request->type == ptr->request.type &&
        !           126:                    request->pid == ptr->request.pid) {
        !           127:                        /* update the time if we 'touch' it */
        !           128:                        ptr->time = current_time;
        !           129:                        return (&ptr->request);
        !           130:                }
        !           131:        }
        !           132:        return ((CTL_MSG *)0);
        !           133: }
        !           134: 
        !           135: insert_table(request, response)
        !           136:        CTL_MSG *request;
        !           137:        CTL_RESPONSE *response;
        !           138: {
        !           139:        register TABLE_ENTRY *ptr;
        !           140:        long current_time;
        !           141: 
        !           142:        gettimeofday(&tp, &txp);
        !           143:        current_time = tp.tv_sec;
        !           144:        request->id_num = new_id();
        !           145:        response->id_num = htonl(request->id_num);
        !           146:        /* insert a new entry into the top of the list */
        !           147:        ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
        !           148:        if (ptr == NIL) {
        !           149:                syslog(LOG_ERR, "insert_table: Out of memory");
        !           150:                _exit(1);
        !           151:        }
        !           152:        ptr->time = current_time;
        !           153:        ptr->request = *request;
        !           154:        ptr->next = table;
        !           155:        if (ptr->next != NIL)
        !           156:                ptr->next->last = ptr;
        !           157:        ptr->last = NIL;
        !           158:        table = ptr;
        !           159: }
        !           160: 
        !           161: /*
        !           162:  * Generate a unique non-zero sequence number
        !           163:  */
        !           164: new_id()
        !           165: {
        !           166:        static int current_id = 0;
        !           167: 
        !           168:        current_id = (current_id + 1) % MAX_ID;
        !           169:        /* 0 is reserved, helps to pick up bugs */
        !           170:        if (current_id == 0)
        !           171:                current_id = 1;
        !           172:        return (current_id);
        !           173: }
        !           174: 
        !           175: /*
        !           176:  * Delete the invitation with id 'id_num'
        !           177:  */
        !           178: delete_invite(id_num)
        !           179:        int id_num;
        !           180: {
        !           181:        register TABLE_ENTRY *ptr;
        !           182: 
        !           183:        ptr = table;
        !           184:        if (debug)
        !           185:                syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
        !           186:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !           187:                if (ptr->request.id_num == id_num)
        !           188:                        break;
        !           189:                if (debug)
        !           190:                        print_request("", &ptr->request);
        !           191:        }
        !           192:        if (ptr != NIL) {
        !           193:                delete(ptr);
        !           194:                return (SUCCESS);
        !           195:        }
        !           196:        return (NOT_HERE);
        !           197: }
        !           198: 
        !           199: /*
        !           200:  * Classic delete from a double-linked list
        !           201:  */
        !           202: delete(ptr)
        !           203:        register TABLE_ENTRY *ptr;
        !           204: {
        !           205: 
        !           206:        if (debug)
        !           207:                print_request("delete", &ptr->request);
        !           208:        if (table == ptr)
        !           209:                table = ptr->next;
        !           210:        else if (ptr->last != NIL)
        !           211:                ptr->last->next = ptr->next;
        !           212:        if (ptr->next != NIL)
        !           213:                ptr->next->last = ptr->last;
        !           214:        free((char *)ptr);
        !           215: }

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