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  */
  36
  37 /*
  38  * Routines to handle insertion, deletion, etc on the table
  39  * of requests kept by the daemon. Nothing fancy here, linear
  40  * search on a double-linked list. A time is kept with each
  41  * entry so that overly old invitations can be eliminated.
  42  *
  43  * Consider this a mis-guided attempt at modularity
  44  */
  45 #include <sys/param.h>
  46 #include <sys/time.h>
  47 #include <sys/socket.h>
  48 #include <protocols/talkd.h>
  49 #include <stdio.h>
  50 #include <stdlib.h>
  51 #include <string.h>
  52 #include <syslog.h>
  53 #include <unistd.h>
  54
  55 #include "extern.h"
  56
  57 #define MAX_ID 16000    /* << 2^15 so I don't have sign troubles */
  58
  59 extern  int debug;
  60 struct  timeval tp;
  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 static void delete(TABLE_ENTRY *);
  72
  73 TABLE_ENTRY *table = NULL;
  74
  75 /*
  76  * Look in the table for an invitation that matches the current
  77  * request looking for an invitation
  78  */
  79 CTL_MSG *
  80 find_match(CTL_MSG *request)
  81 {
  82         TABLE_ENTRY *ptr;
  83         time_t current_time;
  84
  85         gettimeofday(&tp, NULL);
  86         current_time = tp.tv_sec;
  87         if (debug)
  88                 print_request("find_match", request);
  89         for (ptr = table; ptr != NULL; ptr = ptr->next) {
  90                 if ((ptr->time - current_time) > MAX_LIFE) {
  91                         /* the entry is too old */
  92                         if (debug)
  93                                 print_request("deleting expired entry",
  94                                     &ptr->request);
  95                         delete(ptr);
  96                         continue;
  97                 }
  98                 if (debug)
  99                         print_request("", &ptr->request);
 100                 if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
 101                     strcmp(request->r_name, ptr->request.l_name) == 0 &&
 102                      ptr->request.type == LEAVE_INVITE)
 103                         return (&ptr->request);
 104         }
 105         return (NULL);
 106 }
 107
 108 /*
 109  * Look for an identical request, as opposed to a complimentary
 110  * one as find_match does
 111  */
 112 CTL_MSG *
 113 find_request(CTL_MSG *request)
 114 {
 115         TABLE_ENTRY *ptr;
 116         time_t current_time;
 117
 118         gettimeofday(&tp, NULL);
 119         current_time = tp.tv_sec;
 120         /*
 121          * See if this is a repeated message, and check for
 122          * out of date entries in the table while we are it.
 123          */
 124         if (debug)
 125                 print_request("find_request", request);
 126         for (ptr = table; ptr != NULL; ptr = ptr->next) {
 127                 if ((ptr->time - current_time) > MAX_LIFE) {
 128                         /* the entry is too old */
 129                         if (debug)
 130                                 print_request("deleting expired entry",
 131                                     &ptr->request);
 132                         delete(ptr);
 133                         continue;
 134                 }
 135                 if (debug)
 136                         print_request("", &ptr->request);
 137                 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
 138                     strcmp(request->l_name, ptr->request.l_name) == 0 &&
 139                     request->type == ptr->request.type &&
 140                     request->pid == ptr->request.pid) {
 141                         /* update the time if we 'touch' it */
 142                         ptr->time = current_time;
 143                         return (&ptr->request);
 144                 }
 145         }
 146         return (NULL);
 147 }
 148
 149 void
 150 insert_table(CTL_MSG *request, CTL_RESPONSE *response)
 151 {
 152         TABLE_ENTRY *ptr;
 153         time_t current_time;
 154
 155         gettimeofday(&tp, NULL);
 156         current_time = tp.tv_sec;
 157         request->id_num = new_id();
 158         response->id_num = htonl(request->id_num);
 159         /* insert a new entry into the top of the list */
 160         ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
 161         if (ptr == NULL) {
 162                 syslog(LOG_ERR, "insert_table: Out of memory");
 163                 _exit(1);
 164         }
 165         ptr->time = current_time;
 166         ptr->request = *request;
 167         ptr->next = table;
 168         if (ptr->next != NULL)
 169                 ptr->next->last = ptr;
 170         ptr->last = NULL;
 171         table = ptr;
 172 }
 173
 174 /*
 175  * Generate a unique non-zero sequence number
 176  */
 177 int
 178 new_id(void)
 179 {
 180         static int current_id = 0;
 181
 182         current_id = (current_id + 1) % MAX_ID;
 183         /* 0 is reserved, helps to pick up bugs */
 184         if (current_id == 0)
 185                 current_id = 1;
 186         return (current_id);
 187 }
 188
 189 /*
 190  * Delete the invitation with id 'id_num'
 191  */
 192 int
 193 delete_invite(unsigned int id_num)
 194 {
 195         TABLE_ENTRY *ptr;
 196
 197         ptr = table;
 198         if (debug)
 199                 syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
 200         for (ptr = table; ptr != NULL; ptr = ptr->next) {
 201                 if (ptr->request.id_num == id_num)
 202                         break;
 203                 if (debug)
 204                         print_request("", &ptr->request);
 205         }
 206         if (ptr != NULL) {
 207                 delete(ptr);
 208                 return (SUCCESS);
 209         }
 210         return (NOT_HERE);
 211 }
 212
 213 /*
 214  * Classic delete from a double-linked list
 215  */
 216 static void
 217 delete(TABLE_ENTRY *ptr)
 218 {
 219
 220         if (debug)
 221                 print_request("delete", &ptr->request);
 222         if (table == ptr)
 223                 table = ptr->next;
 224         else if (ptr->last != NULL)
 225                 ptr->last->next = ptr->next;
 226         if (ptr->next != NULL)
 227                 ptr->next->last = ptr->last;
 228         free((char *)ptr);
 229 }