libexec/talkd/table.c

   1 /*
   2  * Copyright (c) 1983, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#)table.c  8.1 (Berkeley) 6/4/93
  34  * $FreeBSD: src/libexec/talkd/table.c,v 1.7 1999/08/28 00:10:17 peter Exp $
  35  * $DragonFly: src/libexec/talkd/table.c,v 1.3 2003/11/14 03:54:31 dillon Exp $
  36  */
  37
  38 /*
  39  * Routines to handle insertion, deletion, etc on the table
  40  * of requests kept by the daemon. Nothing fancy here, linear
  41  * search on a double-linked list. A time is kept with each
  42  * entry so that overly old invitations can be eliminated.
  43  *
  44  * Consider this a mis-guided attempt at modularity
  45  */
  46 #include <sys/param.h>
  47 #include <sys/time.h>
  48 #include <sys/socket.h>
  49 #include <protocols/talkd.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <string.h>
  53 #include <syslog.h>
  54 #include <unistd.h>
  55
  56 #define MAX_ID 16000    /* << 2^15 so I don't have sign troubles */
  57
  58 extern  int debug;
  59 struct  timeval tp;
  60 struct  timezone txp;
  61
  62 typedef struct table_entry TABLE_ENTRY;
  63
  64 struct table_entry {
  65         CTL_MSG request;
  66         long    time;
  67         TABLE_ENTRY *next;
  68         TABLE_ENTRY *last;
  69 };
  70
  71 TABLE_ENTRY *table = NULL;
  72
  73 void delete (TABLE_ENTRY *);
  74 CTL_MSG *find_request();
  75 CTL_MSG *find_match();
  76 int new_id (void);
  77 void print_request (char *, CTL_MSG *);
  78
  79 /*
  80  * Look in the table for an invitation that matches the current
  81  * request looking for an invitation
  82  */
  83 CTL_MSG *
  84 find_match(request)
  85         register CTL_MSG *request;
  86 {
  87         register TABLE_ENTRY *ptr;
  88         time_t current_time;
  89
  90         gettimeofday(&tp, &txp);
  91         current_time = tp.tv_sec;
  92         if (debug)
  93                 print_request("find_match", request);
  94         for (ptr = table; ptr != NULL; ptr = ptr->next) {
  95                 if ((ptr->time - current_time) > MAX_LIFE) {
  96                         /* the entry is too old */
  97                         if (debug)
  98                                 print_request("deleting expired entry",
  99                                     &ptr->request);
 100                         delete(ptr);
 101                         continue;
 102                 }
 103                 if (debug)
 104                         print_request("", &ptr->request);
 105                 if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
 106                     strcmp(request->r_name, ptr->request.l_name) == 0 &&
 107                      ptr->request.type == LEAVE_INVITE)
 108                         return (&ptr->request);
 109         }
 110         return (NULL);
 111 }
 112
 113 /*
 114  * Look for an identical request, as opposed to a complimentary
 115  * one as find_match does
 116  */
 117 CTL_MSG *
 118 find_request(request)
 119         register CTL_MSG *request;
 120 {
 121         register TABLE_ENTRY *ptr;
 122         time_t current_time;
 123
 124         gettimeofday(&tp, &txp);
 125         current_time = tp.tv_sec;
 126         /*
 127          * See if this is a repeated message, and check for
 128          * out of date entries in the table while we are it.
 129          */
 130         if (debug)
 131                 print_request("find_request", request);
 132         for (ptr = table; ptr != NULL; ptr = ptr->next) {
 133                 if ((ptr->time - current_time) > MAX_LIFE) {
 134                         /* the entry is too old */
 135                         if (debug)
 136                                 print_request("deleting expired entry",
 137                                     &ptr->request);
 138                         delete(ptr);
 139                         continue;
 140                 }
 141                 if (debug)
 142                         print_request("", &ptr->request);
 143                 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
 144                     strcmp(request->l_name, ptr->request.l_name) == 0 &&
 145                     request->type == ptr->request.type &&
 146                     request->pid == ptr->request.pid) {
 147                         /* update the time if we 'touch' it */
 148                         ptr->time = current_time;
 149                         return (&ptr->request);
 150                 }
 151         }
 152         return (NULL);
 153 }
 154
 155 void
 156 insert_table(request, response)
 157         CTL_MSG *request;
 158         CTL_RESPONSE *response;
 159 {
 160         register TABLE_ENTRY *ptr;
 161         time_t current_time;
 162
 163         gettimeofday(&tp, &txp);
 164         current_time = tp.tv_sec;
 165         request->id_num = new_id();
 166         response->id_num = htonl(request->id_num);
 167         /* insert a new entry into the top of the list */
 168         ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
 169         if (ptr == NULL) {
 170                 syslog(LOG_ERR, "insert_table: Out of memory");
 171                 _exit(1);
 172         }
 173         ptr->time = current_time;
 174         ptr->request = *request;
 175         ptr->next = table;
 176         if (ptr->next != NULL)
 177                 ptr->next->last = ptr;
 178         ptr->last = NULL;
 179         table = ptr;
 180 }
 181
 182 /*
 183  * Generate a unique non-zero sequence number
 184  */
 185 int
 186 new_id()
 187 {
 188         static int current_id = 0;
 189
 190         current_id = (current_id + 1) % MAX_ID;
 191         /* 0 is reserved, helps to pick up bugs */
 192         if (current_id == 0)
 193                 current_id = 1;
 194         return (current_id);
 195 }
 196
 197 /*
 198  * Delete the invitation with id 'id_num'
 199  */
 200 int
 201 delete_invite(id_num)
 202         int id_num;
 203 {
 204         register TABLE_ENTRY *ptr;
 205
 206         ptr = table;
 207         if (debug)
 208                 syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
 209         for (ptr = table; ptr != NULL; ptr = ptr->next) {
 210                 if (ptr->request.id_num == id_num)
 211                         break;
 212                 if (debug)
 213                         print_request("", &ptr->request);
 214         }
 215         if (ptr != NULL) {
 216                 delete(ptr);
 217                 return (SUCCESS);
 218         }
 219         return (NOT_HERE);
 220 }
 221
 222 /*
 223  * Classic delete from a double-linked list
 224  */
 225 void
 226 delete(ptr)
 227         register TABLE_ENTRY *ptr;
 228 {
 229
 230         if (debug)
 231                 print_request("delete", &ptr->request);
 232         if (table == ptr)
 233                 table = ptr->next;
 234         else if (ptr->last != NULL)
 235                 ptr->last->next = ptr->next;
 236         if (ptr->next != NULL)
 237                 ptr->next->last = ptr->last;
 238         free((char *)ptr);
 239 }