talkd.tproj/table.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.0 (the 'License').  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License."
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25  * Copyright (c) 1983, 1993
  26  *      The Regents of the University of California.  All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Redistributions in binary form must reproduce the above copyright
  34  *    notice, this list of conditions and the following disclaimer in the
  35  *    documentation and/or other materials provided with the distribution.
  36  * 3. All advertising materials mentioning features or use of this software
  37  *    must display the following acknowledgement:
  38  *      This product includes software developed by the University of
  39  *      California, Berkeley and its contributors.
  40  * 4. Neither the name of the University nor the names of its contributors
  41  *    may be used to endorse or promote products derived from this software
  42  *    without specific prior written permission.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  45  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  48  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54  * SUCH DAMAGE.
  55  */
  56
  57 #ifndef lint
  58 static char sccsid[] = "@(#)table.c     8.1 (Berkeley) 6/4/93";
  59 #endif /* not lint */
  60
  61 /*
  62  * Routines to handle insertion, deletion, etc on the table
  63  * of requests kept by the daemon. Nothing fancy here, linear
  64  * search on a double-linked list. A time is kept with each
  65  * entry so that overly old invitations can be eliminated.
  66  *
  67  * Consider this a mis-guided attempt at modularity
  68  */
  69 #include <sys/param.h>
  70 #include <sys/time.h>
  71 #include <sys/socket.h>
  72 #include <protocols/talkd.h>
  73 #include <syslog.h>
  74 #include <unistd.h>
  75 #include <stdio.h>
  76 #include <stdlib.h>
  77 #include <string.h>
  78 #include "talkd.h"
  79
  80 #define MAX_ID 16000    /* << 2^15 so I don't have sign troubles */
  81
  82 #define NIL ((TABLE_ENTRY *)0)
  83
  84 extern  int debug;
  85 struct  timeval tp;
  86 struct  timezone txp;
  87
  88 typedef struct table_entry TABLE_ENTRY;
  89
  90 struct table_entry {
  91         CTL_MSG request;
  92         long    time;
  93         TABLE_ENTRY *next;
  94         TABLE_ENTRY *last;
  95 };
  96
  97 TABLE_ENTRY *table = NIL;
  98 CTL_MSG *find_request();
  99 CTL_MSG *find_match();
 100
 101 void    delete __P((TABLE_ENTRY *ptr));
 102
 103 /*
 104  * Look in the table for an invitation that matches the current
 105  * request looking for an invitation
 106  */
 107 CTL_MSG *
 108 find_match(request)
 109         register CTL_MSG *request;
 110 {
 111         register TABLE_ENTRY *ptr;
 112         time_t current_time;
 113
 114         gettimeofday(&tp, &txp);
 115         current_time = tp.tv_sec;
 116         if (debug)
 117                 print_request("find_match", request);
 118         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 119                 if ((ptr->time - current_time) > MAX_LIFE) {
 120                         /* the entry is too old */
 121                         if (debug)
 122                                 print_request("deleting expired entry",
 123                                     &ptr->request);
 124                         delete(ptr);
 125                         continue;
 126                 }
 127                 if (debug)
 128                         print_request("", &ptr->request);
 129                 if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
 130                     strcmp(request->r_name, ptr->request.l_name) == 0 &&
 131                      ptr->request.type == LEAVE_INVITE)
 132                         return (&ptr->request);
 133         }
 134         return ((CTL_MSG *)0);
 135 }
 136
 137 /*
 138  * Look for an identical request, as opposed to a complimentary
 139  * one as find_match does
 140  */
 141 CTL_MSG *
 142 find_request(request)
 143         register CTL_MSG *request;
 144 {
 145         register TABLE_ENTRY *ptr;
 146         time_t current_time;
 147
 148         gettimeofday(&tp, &txp);
 149         current_time = tp.tv_sec;
 150         /*
 151          * See if this is a repeated message, and check for
 152          * out of date entries in the table while we are it.
 153          */
 154         if (debug)
 155                 print_request("find_request", request);
 156         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 157                 if ((ptr->time - current_time) > MAX_LIFE) {
 158                         /* the entry is too old */
 159                         if (debug)
 160                                 print_request("deleting expired entry",
 161                                     &ptr->request);
 162                         delete(ptr);
 163                         continue;
 164                 }
 165                 if (debug)
 166                         print_request("", &ptr->request);
 167                 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
 168                     strcmp(request->l_name, ptr->request.l_name) == 0 &&
 169                     request->type == ptr->request.type &&
 170                     request->pid == ptr->request.pid) {
 171                         /* update the time if we 'touch' it */
 172                         ptr->time = current_time;
 173                         return (&ptr->request);
 174                 }
 175         }
 176         return ((CTL_MSG *)0);
 177 }
 178
 179 void
 180 insert_table(request, response)
 181         CTL_MSG *request;
 182         CTL_RESPONSE *response;
 183 {
 184         register TABLE_ENTRY *ptr;
 185         time_t current_time;
 186
 187         gettimeofday(&tp, &txp);
 188         current_time = tp.tv_sec;
 189         request->id_num = new_id();
 190         response->id_num = htonl(request->id_num);
 191         /* insert a new entry into the top of the list */
 192         ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
 193         if (ptr == NIL) {
 194                 syslog(LOG_ERR, "insert_table: Out of memory");
 195                 _exit(1);
 196         }
 197         ptr->time = current_time;
 198         ptr->request = *request;
 199         ptr->next = table;
 200         if (ptr->next != NIL)
 201                 ptr->next->last = ptr;
 202         ptr->last = NIL;
 203         table = ptr;
 204 }
 205
 206 /*
 207  * Generate a unique non-zero sequence number
 208  */
 209 int
 210 new_id()
 211 {
 212         static int current_id = 0;
 213
 214         current_id = (current_id + 1) % MAX_ID;
 215         /* 0 is reserved, helps to pick up bugs */
 216         if (current_id == 0)
 217                 current_id = 1;
 218         return (current_id);
 219 }
 220
 221 /*
 222  * Delete the invitation with id 'id_num'
 223  */
 224 int
 225 delete_invite(id_num)
 226         int id_num;
 227 {
 228         register TABLE_ENTRY *ptr;
 229
 230         ptr = table;
 231         if (debug)
 232                 syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
 233         for (ptr = table; ptr != NIL; ptr = ptr->next) {
 234                 if (ptr->request.id_num == id_num)
 235                         break;
 236                 if (debug)
 237                         print_request("", &ptr->request);
 238         }
 239         if (ptr != NIL) {
 240                 delete(ptr);
 241                 return (SUCCESS);
 242         }
 243         return (NOT_HERE);
 244 }
 245
 246 /*
 247  * Classic delete from a double-linked list
 248  */
 249 void
 250 delete(ptr)
 251         register TABLE_ENTRY *ptr;
 252 {
 253
 254         if (debug)
 255                 print_request("delete", &ptr->request);
 256         if (table == ptr)
 257                 table = ptr->next;
 258         else if (ptr->last != NIL)
 259                 ptr->last->next = ptr->next;
 260         if (ptr->next != NIL)
 261                 ptr->next->last = ptr->last;
 262         free((char *)ptr);
 263 }