2.11BSD#431 - /usr/src/libexec/talkd/table.c

   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: #if defined(DOSCCS) && !defined(lint)
   8: static char sccsid[] = "@(#)table.c	5.2.1 (2.11BSD GTE) 1/1/94";
   9: #endif
  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: #include <sys/types.h>
  23: #include <netinet/in.h>
  24: 
  25: #include <protocols/talkd.h>
  26: 
  27: #define MAX_ID 16000    /* << 2^15 so I don't have sign troubles */
  28: 
  29: #define NIL ((TABLE_ENTRY *)0)
  30: 
  31: extern  int debug;
  32: struct  timeval tp;
  33: struct  timezone *txp;
  34: 
  35: typedef struct table_entry TABLE_ENTRY;
  36: 
  37: struct table_entry {
  38:     CTL_MSG request;
  39:     long    time;
  40:     TABLE_ENTRY *next;
  41:     TABLE_ENTRY *last;
  42: };
  43: 
  44: TABLE_ENTRY *table = NIL;
  45: CTL_MSG *find_request();
  46: CTL_MSG *find_match();
  47: char    *malloc();
  48: 
  49: /*
  50:  * Look in the table for an invitation that matches the current
  51:  * request looking for an invitation
  52:  */
  53: CTL_MSG *
  54: find_match(request)
  55:     register CTL_MSG *request;
  56: {
  57:     register TABLE_ENTRY *ptr;
  58:     long current_time;
  59: 
  60:     gettimeofday(&tp, &txp);
  61:     current_time = tp.tv_sec;
  62:     if (debug)
  63:         print_request("find_match", request);
  64:     for (ptr = table; ptr != NIL; ptr = ptr->next) {
  65:         if ((ptr->time - current_time) > MAX_LIFE) {
  66:             /* the entry is too old */
  67:             if (debug)
  68:                 print_request("deleting expired entry",
  69:                     &ptr->request);
  70:             delete(ptr);
  71:             continue;
  72:         }
  73:         if (debug)
  74:             print_request("", &ptr->request);
  75:         if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
  76:             strcmp(request->r_name, ptr->request.l_name) == 0 &&
  77:              ptr->request.type == LEAVE_INVITE)
  78:             return (&ptr->request);
  79:     }
  80:     return ((CTL_MSG *)0);
  81: }
  82: 
  83: /*
  84:  * Look for an identical request, as opposed to a complimentary
  85:  * one as find_match does
  86:  */
  87: CTL_MSG *
  88: find_request(request)
  89:     register CTL_MSG *request;
  90: {
  91:     register TABLE_ENTRY *ptr;
  92:     long current_time;
  93: 
  94:     gettimeofday(&tp, &txp);
  95:     current_time = tp.tv_sec;
  96:     /*
  97: 	 * See if this is a repeated message, and check for
  98: 	 * out of date entries in the table while we are it.
  99: 	 */
 100:     if (debug)
 101:         print_request("find_request", request);
 102:     for (ptr = table; ptr != NIL; ptr = ptr->next) {
 103:         if ((ptr->time - current_time) > MAX_LIFE) {
 104:             /* the entry is too old */
 105:             if (debug)
 106:                 print_request("deleting expired entry",
 107:                     &ptr->request);
 108:             delete(ptr);
 109:             continue;
 110:         }
 111:         if (debug)
 112:             print_request("", &ptr->request);
 113:         if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
 114:             strcmp(request->l_name, ptr->request.l_name) == 0 &&
 115:             request->type == ptr->request.type &&
 116:             request->pid == ptr->request.pid) {
 117:             /* update the time if we 'touch' it */
 118:             ptr->time = current_time;
 119:             return (&ptr->request);
 120:         }
 121:     }
 122:     return ((CTL_MSG *)0);
 123: }
 124: 
 125: insert_table(request, response)
 126:     CTL_MSG *request;
 127:     CTL_RESPONSE *response;
 128: {
 129:     register TABLE_ENTRY *ptr;
 130:     long current_time;
 131: 
 132:     gettimeofday(&tp, &txp);
 133:     current_time = tp.tv_sec;
 134:     request->id_num = new_id();
 135:     response->id_num = htonl(request->id_num);
 136:     /* insert a new entry into the top of the list */
 137:     ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
 138:     if (ptr == NIL) {
 139:         syslog(LOG_ERR, "insert_table: Out of memory");
 140:         _exit(1);
 141:     }
 142:     ptr->time = current_time;
 143:     ptr->request = *request;
 144:     ptr->next = table;
 145:     if (ptr->next != NIL)
 146:         ptr->next->last = ptr;
 147:     ptr->last = NIL;
 148:     table = ptr;
 149: }
 150: 
 151: /*
 152:  * Generate a unique non-zero sequence number
 153:  */
 154: new_id()
 155: {
 156:     static int current_id = 0;
 157: 
 158:     current_id = (current_id + 1) % MAX_ID;
 159:     /* 0 is reserved, helps to pick up bugs */
 160:     if (current_id == 0)
 161:         current_id = 1;
 162:     return (current_id);
 163: }
 164: 
 165: /*
 166:  * Delete the invitation with id 'id_num'
 167:  */
 168: delete_invite(id_num)
 169:     long id_num;
 170: {
 171:     register TABLE_ENTRY *ptr;
 172: 
 173:     ptr = table;
 174:     if (debug)
 175:         syslog(LOG_DEBUG, "delete_invite(%ld)", id_num);
 176:     for (ptr = table; ptr != NIL; ptr = ptr->next) {
 177:         if (ptr->request.id_num == id_num)
 178:             break;
 179:         if (debug)
 180:             print_request("", &ptr->request);
 181:     }
 182:     if (ptr != NIL) {
 183:         delete(ptr);
 184:         return (SUCCESS);
 185:     }
 186:     return (NOT_HERE);
 187: }
 188: 
 189: /*
 190:  * Classic delete from a double-linked list
 191:  */
 192: delete(ptr)
 193:     register TABLE_ENTRY *ptr;
 194: {
 195: 
 196:     if (debug)
 197:         print_request("delete", &ptr->request);
 198:     if (table == ptr)
 199:         table = ptr->next;
 200:     else if (ptr->last != NIL)
 201:         ptr->last->next = ptr->next;
 202:     if (ptr->next != NIL)
 203:         ptr->next->last = ptr->last;
 204:     free((char *)ptr);
 205: }

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