talkd.tproj/table.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1983, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58 #ifndef lint
  59 static char sccsid[] = "@(#)table.c     8.1 (Berkeley) 6/4/93";
  60 #endif /* not lint */
  61
  62 /*
  63  * Routines to handle insertion, deletion, etc on the table
  64  * of requests kept by the daemon. Nothing fancy here, linear
  65  * search on a double-linked list. A time is kept with each
  66  * entry so that overly old invitations can be eliminated.
  67  *
  68  * Consider this a mis-guided attempt at modularity
  69  */
  70 #include <sys/param.h>
  71 #include <sys/time.h>
  72 #include <sys/socket.h>
  73 #include <protocols/talkd.h>
  74 #include <syslog.h>
  75 #include <unistd.h>
  76 #include <stdio.h>
  77 #include <stdlib.h>
  78 #include <string.h>
  79 #include "talkd.h"
  80
  81 #define MAX_ID 16000    /* << 2^15 so I don't have sign troubles */
  82
  83 #define NIL ((TABLE_ENTRY *)0)
  84
  85 extern  int debug;
  86 struct  timeval tp;
  87 struct  timezone txp;
  88
  89 typedef struct table_entry TABLE_ENTRY;
  90
  91 struct table_entry {
  92         CTL_MSG request;
  93         long    time;
  94         TABLE_ENTRY *next;
  95         TABLE_ENTRY *last;
  96 };
  97
  98 TABLE_ENTRY *table = NIL;
  99 CTL_MSG *find_request();
 100 CTL_MSG *find_match();
 101
 102 void    delete __P((TABLE_ENTRY *ptr));
 103
 104 /*
 105  * Look in the table for an invitation that matches the current
 106  * request looking for an invitation
 107  */
 108 CTL_MSG *
 109 find_match(request)
 110         register CTL_MSG *request;
 111 {
 112         register TABLE_ENTRY *ptr;
 113         time_t current_time;
 114
 115         gettimeofday(&tp, &txp);
 116         current_time = tp.tv_sec;
 117         if (debug)
 118                 print_request("find_match", request);
 119         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 120                 if ((ptr->time - current_time) > MAX_LIFE) {
 121                         /* the entry is too old */
 122                         if (debug)
 123                                 print_request("deleting expired entry",
 124                                     &ptr->request);
 125                         delete(ptr);
 126                         continue;
 127                 }
 128                 if (debug)
 129                         print_request("", &ptr->request);
 130                 if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
 131                     strcmp(request->r_name, ptr->request.l_name) == 0 &&
 132                      ptr->request.type == LEAVE_INVITE)
 133                         return (&ptr->request);
 134         }
 135         return ((CTL_MSG *)0);
 136 }
 137
 138 /*
 139  * Look for an identical request, as opposed to a complimentary
 140  * one as find_match does
 141  */
 142 CTL_MSG *
 143 find_request(request)
 144         register CTL_MSG *request;
 145 {
 146         register TABLE_ENTRY *ptr;
 147         time_t current_time;
 148
 149         gettimeofday(&tp, &txp);
 150         current_time = tp.tv_sec;
 151         /*
 152          * See if this is a repeated message, and check for
 153          * out of date entries in the table while we are it.
 154          */
 155         if (debug)
 156                 print_request("find_request", request);
 157         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 158                 if ((ptr->time - current_time) > MAX_LIFE) {
 159                         /* the entry is too old */
 160                         if (debug)
 161                                 print_request("deleting expired entry",
 162                                     &ptr->request);
 163                         delete(ptr);
 164                         continue;
 165                 }
 166                 if (debug)
 167                         print_request("", &ptr->request);
 168                 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
 169                     strcmp(request->l_name, ptr->request.l_name) == 0 &&
 170                     request->type == ptr->request.type &&
 171                     request->pid == ptr->request.pid) {
 172                         /* update the time if we 'touch' it */
 173                         ptr->time = current_time;
 174                         return (&ptr->request);
 175                 }
 176         }
 177         return ((CTL_MSG *)0);
 178 }
 179
 180 void
 181 insert_table(request, response)
 182         CTL_MSG *request;
 183         CTL_RESPONSE *response;
 184 {
 185         register TABLE_ENTRY *ptr;
 186         time_t current_time;
 187
 188         gettimeofday(&tp, &txp);
 189         current_time = tp.tv_sec;
 190         request->id_num = new_id();
 191         response->id_num = htonl(request->id_num);
 192         /* insert a new entry into the top of the list */
 193         ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
 194         if (ptr == NIL) {
 195                 syslog(LOG_ERR, "insert_table: Out of memory");
 196                 _exit(1);
 197         }
 198         ptr->time = current_time;
 199         ptr->request = *request;
 200         ptr->next = table;
 201         if (ptr->next != NIL)
 202                 ptr->next->last = ptr;
 203         ptr->last = NIL;
 204         table = ptr;
 205 }
 206
 207 /*
 208  * Generate a unique non-zero sequence number
 209  */
 210 int
 211 new_id()
 212 {
 213         static int current_id = 0;
 214
 215         current_id = (current_id + 1) % MAX_ID;
 216         /* 0 is reserved, helps to pick up bugs */
 217         if (current_id == 0)
 218                 current_id = 1;
 219         return (current_id);
 220 }
 221
 222 /*
 223  * Delete the invitation with id 'id_num'
 224  */
 225 int
 226 delete_invite(id_num)
 227         int id_num;
 228 {
 229         register TABLE_ENTRY *ptr;
 230
 231         ptr = table;
 232         if (debug)
 233                 syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
 234         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 235                 if (ptr->request.id_num == id_num)
 236                         break;
 237                 if (debug)
 238                         print_request("", &ptr->request);
 239         }
 240         if (ptr != NIL) {
 241                 delete(ptr);
 242                 return (SUCCESS);
 243         }
 244         return (NOT_HERE);
 245 }
 246
 247 /*
 248  * Classic delete from a double-linked list
 249  */
 250 void
 251 delete(ptr)
 252         register TABLE_ENTRY *ptr;
 253 {
 254
 255         if (debug)
 256                 print_request("delete", &ptr->request);
 257         if (table == ptr)
 258                 table = ptr->next;
 259         else if (ptr->last != NIL)
 260                 ptr->last->next = ptr->next;
 261         if (ptr->next != NIL)
 262                 ptr->next->last = ptr->last;
 263         free((char *)ptr);
 264 }