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 #define NIL ((TABLE_ENTRY *)0)
  59
  60 extern  int debug;
  61 struct  timeval tp;
  62 struct  timezone txp;
  63
  64 typedef struct table_entry TABLE_ENTRY;
  65
  66 struct table_entry {
  67         CTL_MSG request;
  68         long    time;
  69         TABLE_ENTRY *next;
  70         TABLE_ENTRY *last;
  71 };
  72
  73 TABLE_ENTRY *table = NIL;
  74
  75 void delete (TABLE_ENTRY *);
  76 CTL_MSG *find_request();
  77 CTL_MSG *find_match();
  78 int new_id (void);
  79 void print_request (char *, CTL_MSG *);
  80
  81 /*
  82  * Look in the table for an invitation that matches the current
  83  * request looking for an invitation
  84  */
  85 CTL_MSG *
  86 find_match(request)
  87         register CTL_MSG *request;
  88 {
  89         register TABLE_ENTRY *ptr;
  90         time_t current_time;
  91
  92         gettimeofday(&tp, &txp);
  93         current_time = tp.tv_sec;
  94         if (debug)
  95                 print_request("find_match", request);
  96         for (ptr = table; ptr != NIL; ptr = ptr->next) {
  97                 if ((ptr->time - current_time) > MAX_LIFE) {
  98                         /* the entry is too old */
  99                         if (debug)
 100                                 print_request("deleting expired entry",
 101                                     &ptr->request);
 102                         delete(ptr);
 103                         continue;
 104                 }
 105                 if (debug)
 106                         print_request("", &ptr->request);
 107                 if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
 108                     strcmp(request->r_name, ptr->request.l_name) == 0 &&
 109                      ptr->request.type == LEAVE_INVITE)
 110                         return (&ptr->request);
 111         }
 112         return ((CTL_MSG *)0);
 113 }
 114
 115 /*
 116  * Look for an identical request, as opposed to a complimentary
 117  * one as find_match does
 118  */
 119 CTL_MSG *
 120 find_request(request)
 121         register CTL_MSG *request;
 122 {
 123         register TABLE_ENTRY *ptr;
 124         time_t current_time;
 125
 126         gettimeofday(&tp, &txp);
 127         current_time = tp.tv_sec;
 128         /*
 129          * See if this is a repeated message, and check for
 130          * out of date entries in the table while we are it.
 131          */
 132         if (debug)
 133                 print_request("find_request", request);
 134         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 135                 if ((ptr->time - current_time) > MAX_LIFE) {
 136                         /* the entry is too old */
 137                         if (debug)
 138                                 print_request("deleting expired entry",
 139                                     &ptr->request);
 140                         delete(ptr);
 141                         continue;
 142                 }
 143                 if (debug)
 144                         print_request("", &ptr->request);
 145                 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
 146                     strcmp(request->l_name, ptr->request.l_name) == 0 &&
 147                     request->type == ptr->request.type &&
 148                     request->pid == ptr->request.pid) {
 149                         /* update the time if we 'touch' it */
 150                         ptr->time = current_time;
 151                         return (&ptr->request);
 152                 }
 153         }
 154         return ((CTL_MSG *)0);
 155 }
 156
 157 void
 158 insert_table(request, response)
 159         CTL_MSG *request;
 160         CTL_RESPONSE *response;
 161 {
 162         register TABLE_ENTRY *ptr;
 163         time_t current_time;
 164
 165         gettimeofday(&tp, &txp);
 166         current_time = tp.tv_sec;
 167         request->id_num = new_id();
 168         response->id_num = htonl(request->id_num);
 169         /* insert a new entry into the top of the list */
 170         ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
 171         if (ptr == NIL) {
 172                 syslog(LOG_ERR, "insert_table: Out of memory");
 173                 _exit(1);
 174         }
 175         ptr->time = current_time;
 176         ptr->request = *request;
 177         ptr->next = table;
 178         if (ptr->next != NIL)
 179                 ptr->next->last = ptr;
 180         ptr->last = NIL;
 181         table = ptr;
 182 }
 183
 184 /*
 185  * Generate a unique non-zero sequence number
 186  */
 187 int
 188 new_id()
 189 {
 190         static int current_id = 0;
 191
 192         current_id = (current_id + 1) % MAX_ID;
 193         /* 0 is reserved, helps to pick up bugs */
 194         if (current_id == 0)
 195                 current_id = 1;
 196         return (current_id);
 197 }
 198
 199 /*
 200  * Delete the invitation with id 'id_num'
 201  */
 202 int
 203 delete_invite(id_num)
 204         int id_num;
 205 {
 206         register TABLE_ENTRY *ptr;
 207
 208         ptr = table;
 209         if (debug)
 210                 syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
 211         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 212                 if (ptr->request.id_num == id_num)
 213                         break;
 214                 if (debug)
 215                         print_request("", &ptr->request);
 216         }
 217         if (ptr != NIL) {
 218                 delete(ptr);
 219                 return (SUCCESS);
 220         }
 221         return (NOT_HERE);
 222 }
 223
 224 /*
 225  * Classic delete from a double-linked list
 226  */
 227 void
 228 delete(ptr)
 229         register TABLE_ENTRY *ptr;
 230 {
 231
 232         if (debug)
 233                 print_request("delete", &ptr->request);
 234         if (table == ptr)
 235                 table = ptr->next;
 236         else if (ptr->last != NIL)
 237                 ptr->last->next = ptr->next;
 238         if (ptr->next != NIL)
 239                 ptr->next->last = ptr->last;
 240         free((char *)ptr);
 241 }