libexec/talkd/table.c

   1 /*      $NetBSD: table.c,v 1.9 2009/03/16 01:04:32 lukem Exp $  */
   2
   3 /*
   4  * Copyright (c) 1983, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 #if 0
  35 static char sccsid[] = "@(#)table.c     8.1 (Berkeley) 6/4/93";
  36 #else
  37 __RCSID("$NetBSD: table.c,v 1.9 2009/03/16 01:04:32 lukem Exp $");
  38 #endif
  39 #endif /* not lint */
  40
  41 /*
  42  * Routines to handle insertion, deletion, etc on the table
  43  * of requests kept by the daemon. Nothing fancy here, linear
  44  * search on a double-linked list. A time is kept with each
  45  * entry so that overly old invitations can be eliminated.
  46  *
  47  * Consider this a mis-guided attempt at modularity
  48  */
  49 #include <sys/param.h>
  50 #include <sys/time.h>
  51 #include <sys/socket.h>
  52 #include <protocols/talkd.h>
  53 #include <inttypes.h>
  54 #include <syslog.h>
  55 #include <unistd.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59 #include "extern.h"
  60
  61 #define MAX_ID 16000    /* << 2^15 so I don't have sign troubles */
  62
  63 #define NIL ((TABLE_ENTRY *)0)
  64
  65 struct  timeval tp;
  66
  67 typedef struct table_entry TABLE_ENTRY;
  68
  69 struct table_entry {
  70         CTL_MSG request;
  71         time_t  time;
  72         TABLE_ENTRY *next;
  73         TABLE_ENTRY *last;
  74 };
  75
  76 TABLE_ENTRY *table = NIL;
  77
  78 static void delete(TABLE_ENTRY *);
  79
  80 /*
  81  * Look in the table for an invitation that matches the current
  82  * request looking for an invitation
  83  */
  84 CTL_MSG *
  85 find_match(CTL_MSG *request)
  86 {
  87         TABLE_ENTRY *ptr;
  88         time_t current_time;
  89
  90         gettimeofday(&tp, NULL);
  91         current_time = tp.tv_sec;
  92         if (debug)
  93                 print_request("find_match", request);
  94         for (ptr = table; ptr != NIL; 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 ((CTL_MSG *)0);
 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(CTL_MSG *request)
 119 {
 120         TABLE_ENTRY *ptr;
 121         time_t current_time;
 122
 123         gettimeofday(&tp, NULL);
 124         current_time = tp.tv_sec;
 125         /*
 126          * See if this is a repeated message, and check for
 127          * out of date entries in the table while we are it.
 128          */
 129         if (debug)
 130                 print_request("find_request", request);
 131         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 132                 if ((ptr->time - current_time) > MAX_LIFE) {
 133                         /* the entry is too old */
 134                         if (debug)
 135                                 print_request("deleting expired entry",
 136                                     &ptr->request);
 137                         delete(ptr);
 138                         continue;
 139                 }
 140                 if (debug)
 141                         print_request("", &ptr->request);
 142                 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
 143                     strcmp(request->l_name, ptr->request.l_name) == 0 &&
 144                     request->type == ptr->request.type &&
 145                     request->pid == ptr->request.pid) {
 146                         /* update the time if we 'touch' it */
 147                         ptr->time = current_time;
 148                         return (&ptr->request);
 149                 }
 150         }
 151         return ((CTL_MSG *)0);
 152 }
 153
 154 void
 155 insert_table(CTL_MSG *request, CTL_RESPONSE *response)
 156 {
 157         TABLE_ENTRY *ptr;
 158         time_t current_time;
 159
 160         gettimeofday(&tp, NULL);
 161         current_time = tp.tv_sec;
 162         request->id_num = new_id();
 163         response->id_num = htonl(request->id_num);
 164         /* insert a new entry into the top of the list */
 165         ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
 166         if (ptr == NIL) {
 167                 syslog(LOG_ERR, "insert_table: Out of memory");
 168                 _exit(1);
 169         }
 170         ptr->time = current_time;
 171         ptr->request = *request;
 172         ptr->next = table;
 173         if (ptr->next != NIL)
 174                 ptr->next->last = ptr;
 175         ptr->last = NIL;
 176         table = ptr;
 177 }
 178
 179 /*
 180  * Generate a unique non-zero sequence number
 181  */
 182 uint32_t
 183 new_id(void)
 184 {
 185         static uint32_t current_id = 0;
 186
 187         current_id = (current_id + 1) % MAX_ID;
 188         /* 0 is reserved, helps to pick up bugs */
 189         if (current_id == 0)
 190                 current_id = 1;
 191         return (current_id);
 192 }
 193
 194 /*
 195  * Delete the invitation with id 'id_num'
 196  */
 197 u_char
 198 delete_invite(uint32_t id_num)
 199 {
 200         TABLE_ENTRY *ptr;
 201
 202         ptr = table;
 203         if (debug)
 204                 syslog(LOG_DEBUG, "delete_invite(%"PRIu32")", id_num);
 205         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 206                 if (ptr->request.id_num == id_num)
 207                         break;
 208                 if (debug)
 209                         print_request("", &ptr->request);
 210         }
 211         if (ptr != NIL) {
 212                 delete(ptr);
 213                 return (SUCCESS);
 214         }
 215         return (NOT_HERE);
 216 }
 217
 218 /*
 219  * Classic delete from a double-linked list
 220  */
 221 static void
 222 delete(TABLE_ENTRY *ptr)
 223 {
 224
 225         if (debug)
 226                 print_request("delete", &ptr->request);
 227         if (table == ptr)
 228                 table = ptr->next;
 229         else if (ptr->last != NIL)
 230                 ptr->last->next = ptr->next;
 231         if (ptr->next != NIL)
 232                 ptr->next->last = ptr->last;
 233         free((char *)ptr);
 234 }