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