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Annotation of 43BSD/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.  The Berkeley software License Agreement
        !             4:  * specifies the terms and conditions for redistribution.
        !             5:  */
        !             6: 
        !             7: #ifndef lint
        !             8: static char sccsid[] = "@(#)table.c    5.2 (Berkeley) 3/13/86";
        !             9: #endif not lint
        !            10: 
        !            11: /*
        !            12:  * Routines to handle insertion, deletion, etc on the table
        !            13:  * of requests kept by the daemon. Nothing fancy here, linear
        !            14:  * search on a double-linked list. A time is kept with each 
        !            15:  * entry so that overly old invitations can be eliminated.
        !            16:  *
        !            17:  * Consider this a mis-guided attempt at modularity
        !            18:  */
        !            19: #include <stdio.h>
        !            20: #include <sys/time.h>
        !            21: #include <syslog.h>
        !            22: 
        !            23: #include <protocols/talkd.h>
        !            24: 
        !            25: #define MAX_ID 16000   /* << 2^15 so I don't have sign troubles */
        !            26: 
        !            27: #define NIL ((TABLE_ENTRY *)0)
        !            28: 
        !            29: extern int debug;
        !            30: struct timeval tp;
        !            31: struct timezone *txp;
        !            32: 
        !            33: typedef struct table_entry TABLE_ENTRY;
        !            34: 
        !            35: struct table_entry {
        !            36:        CTL_MSG request;
        !            37:        long    time;
        !            38:        TABLE_ENTRY *next;
        !            39:        TABLE_ENTRY *last;
        !            40: };
        !            41: 
        !            42: TABLE_ENTRY *table = NIL;
        !            43: CTL_MSG *find_request();
        !            44: CTL_MSG *find_match();
        !            45: char   *malloc();
        !            46: 
        !            47: /*
        !            48:  * Look in the table for an invitation that matches the current
        !            49:  * request looking for an invitation
        !            50:  */
        !            51: CTL_MSG *
        !            52: find_match(request)
        !            53:        register CTL_MSG *request;
        !            54: {
        !            55:        register TABLE_ENTRY *ptr;
        !            56:        long current_time;
        !            57: 
        !            58:        gettimeofday(&tp, &txp);
        !            59:        current_time = tp.tv_sec;
        !            60:        if (debug)
        !            61:                print_request("find_match", request);
        !            62:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !            63:                if ((ptr->time - current_time) > MAX_LIFE) {
        !            64:                        /* the entry is too old */
        !            65:                        if (debug)
        !            66:                                print_request("deleting expired entry",
        !            67:                                    &ptr->request);
        !            68:                        delete(ptr);
        !            69:                        continue;
        !            70:                }
        !            71:                if (debug)
        !            72:                        print_request("", &ptr->request);
        !            73:                if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
        !            74:                    strcmp(request->r_name, ptr->request.l_name) == 0 &&
        !            75:                     ptr->request.type == LEAVE_INVITE)
        !            76:                        return (&ptr->request);
        !            77:        }
        !            78:        return ((CTL_MSG *)0);
        !            79: }
        !            80: 
        !            81: /*
        !            82:  * Look for an identical request, as opposed to a complimentary
        !            83:  * one as find_match does 
        !            84:  */
        !            85: CTL_MSG *
        !            86: find_request(request)
        !            87:        register CTL_MSG *request;
        !            88: {
        !            89:        register TABLE_ENTRY *ptr;
        !            90:        long current_time;
        !            91: 
        !            92:        gettimeofday(&tp, &txp);
        !            93:        current_time = tp.tv_sec;
        !            94:        /*
        !            95:         * See if this is a repeated message, and check for
        !            96:         * out of date entries in the table while we are it.
        !            97:         */
        !            98:        if (debug)
        !            99:                print_request("find_request", request);
        !           100:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !           101:                if ((ptr->time - current_time) > MAX_LIFE) {
        !           102:                        /* the entry is too old */
        !           103:                        if (debug)
        !           104:                                print_request("deleting expired entry",
        !           105:                                    &ptr->request);
        !           106:                        delete(ptr);
        !           107:                        continue;
        !           108:                }
        !           109:                if (debug)
        !           110:                        print_request("", &ptr->request);
        !           111:                if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
        !           112:                    strcmp(request->l_name, ptr->request.l_name) == 0 &&
        !           113:                    request->type == ptr->request.type &&
        !           114:                    request->pid == ptr->request.pid) {
        !           115:                        /* update the time if we 'touch' it */
        !           116:                        ptr->time = current_time;
        !           117:                        return (&ptr->request);
        !           118:                }
        !           119:        }
        !           120:        return ((CTL_MSG *)0);
        !           121: }
        !           122: 
        !           123: insert_table(request, response)
        !           124:        CTL_MSG *request;
        !           125:        CTL_RESPONSE *response;
        !           126: {
        !           127:        register TABLE_ENTRY *ptr;
        !           128:        long current_time;
        !           129: 
        !           130:        gettimeofday(&tp, &txp);
        !           131:        current_time = tp.tv_sec;
        !           132:        request->id_num = new_id();
        !           133:        response->id_num = htonl(request->id_num);
        !           134:        /* insert a new entry into the top of the list */
        !           135:        ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
        !           136:        if (ptr == NIL) {
        !           137:                syslog(LOG_ERR, "insert_table: Out of memory");
        !           138:                _exit(1);
        !           139:        }
        !           140:        ptr->time = current_time;
        !           141:        ptr->request = *request;
        !           142:        ptr->next = table;
        !           143:        if (ptr->next != NIL)
        !           144:                ptr->next->last = ptr;
        !           145:        ptr->last = NIL;
        !           146:        table = ptr;
        !           147: }
        !           148: 
        !           149: /*
        !           150:  * Generate a unique non-zero sequence number
        !           151:  */
        !           152: new_id()
        !           153: {
        !           154:        static int current_id = 0;
        !           155: 
        !           156:        current_id = (current_id + 1) % MAX_ID;
        !           157:        /* 0 is reserved, helps to pick up bugs */
        !           158:        if (current_id == 0)
        !           159:                current_id = 1;
        !           160:        return (current_id);
        !           161: }
        !           162: 
        !           163: /*
        !           164:  * Delete the invitation with id 'id_num'
        !           165:  */
        !           166: delete_invite(id_num)
        !           167:        int id_num;
        !           168: {
        !           169:        register TABLE_ENTRY *ptr;
        !           170: 
        !           171:        ptr = table;
        !           172:        if (debug)
        !           173:                syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
        !           174:        for (ptr = table; ptr != NIL; ptr = ptr->next) {
        !           175:                if (ptr->request.id_num == id_num)
        !           176:                        break;
        !           177:                if (debug)
        !           178:                        print_request("", &ptr->request);
        !           179:        }
        !           180:        if (ptr != NIL) {
        !           181:                delete(ptr);
        !           182:                return (SUCCESS);
        !           183:        }
        !           184:        return (NOT_HERE);
        !           185: }
        !           186: 
        !           187: /*
        !           188:  * Classic delete from a double-linked list
        !           189:  */
        !           190: delete(ptr)
        !           191:        register TABLE_ENTRY *ptr;
        !           192: {
        !           193: 
        !           194:        if (debug)
        !           195:                print_request("delete", &ptr->request);
        !           196:        if (table == ptr)
        !           197:                table = ptr->next;
        !           198:        else if (ptr->last != NIL)
        !           199:                ptr->last->next = ptr->next;
        !           200:        if (ptr->next != NIL)
        !           201:                ptr->next->last = ptr->last;
        !           202:        free((char *)ptr);
        !           203: }

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