1 /* $OpenBSD: table.c,v 1.14 2009/10/27 23:59:31 deraadt Exp $ */ 2 3 /* 4 * Copyright (c) 1983 Regents of the University of California. 5 * 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 /* 33 * Routines to handle insertion, deletion, etc on the table 34 * of requests kept by the daemon. Nothing fancy here, linear 35 * search on a double-linked list. A time is kept with each 36 * entry so that overly old invitations can be eliminated. 37 * 38 * Consider this a mis-guided attempt at modularity 39 */ 40 #include <sys/param.h> 41 #include <sys/time.h> 42 #include <sys/socket.h> 43 #include <sys/queue.h> 44 #include <protocols/talkd.h> 45 #include <syslog.h> 46 #include <unistd.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include "talkd.h" 51 52 #define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */ 53 54 struct timeval tp; 55 struct timezone txp; 56 57 typedef struct table_entry TABLE_ENTRY; 58 59 struct table_entry { 60 CTL_MSG request; 61 time_t time; 62 TAILQ_ENTRY(table_entry) list; 63 }; 64 TAILQ_HEAD(, table_entry) table; 65 66 static void delete(TABLE_ENTRY *); 67 68 /* 69 * Init the table 70 */ 71 void 72 init_table(void) 73 { 74 TAILQ_INIT(&table); 75 } 76 77 /* 78 * Look in the table for an invitation that matches the current 79 * request looking for an invitation 80 */ 81 CTL_MSG * 82 find_match(CTL_MSG *request) 83 { 84 TABLE_ENTRY *ptr, *next; 85 time_t current_time; 86 87 gettimeofday(&tp, &txp); 88 current_time = tp.tv_sec; 89 if (debug) 90 print_request("find_match", request); 91 for (ptr = TAILQ_FIRST(&table); ptr != NULL; ptr = next) { 92 next = TAILQ_NEXT(ptr, list); 93 if ((current_time - ptr->time) > MAX_LIFE) { 94 /* the entry is too old */ 95 if (debug) 96 print_request("deleting expired entry", 97 &ptr->request); 98 delete(ptr); 99 continue; 100 } 101 if (debug) 102 print_request("", &ptr->request); 103 if (ptr->request.type == LEAVE_INVITE && 104 strcmp(request->l_name, ptr->request.r_name) == 0 && 105 strcmp(request->r_name, ptr->request.l_name) == 0) 106 return (&ptr->request); 107 } 108 if (debug) 109 syslog(LOG_DEBUG, "find_match: not found"); 110 111 return ((CTL_MSG *)0); 112 } 113 114 /* 115 * Look for an identical request, as opposed to a complimentary 116 * one as find_match does 117 */ 118 CTL_MSG * 119 find_request(CTL_MSG *request) 120 { 121 TABLE_ENTRY *ptr, *next; 122 time_t current_time; 123 124 gettimeofday(&tp, &txp); 125 current_time = tp.tv_sec; 126 /* 127 * See if this is a repeated message, and check for 128 * out of date entries in the table while we are it. 129 */ 130 if (debug) 131 print_request("find_request", request); 132 for (ptr = TAILQ_FIRST(&table); ptr != NULL; ptr = next) { 133 next = TAILQ_NEXT(ptr, list); 134 if ((current_time - ptr->time) > MAX_LIFE) { 135 /* the entry is too old */ 136 if (debug) 137 print_request("deleting expired entry", 138 &ptr->request); 139 delete(ptr); 140 continue; 141 } 142 if (debug) 143 print_request("", &ptr->request); 144 if (request->pid == ptr->request.pid && 145 request->type == ptr->request.type && 146 strcmp(request->r_name, ptr->request.r_name) == 0 && 147 strcmp(request->l_name, ptr->request.l_name) == 0) { 148 /* update the time if we 'touch' it */ 149 ptr->time = current_time; 150 return (&ptr->request); 151 } 152 } 153 return ((CTL_MSG *)0); 154 } 155 156 void 157 insert_table(CTL_MSG *request, CTL_RESPONSE *response) 158 { 159 TABLE_ENTRY *ptr; 160 time_t current_time; 161 162 if (debug) 163 print_request( "insert_table", request ); 164 gettimeofday(&tp, &txp); 165 current_time = tp.tv_sec; 166 request->id_num = new_id(); 167 response->id_num = htonl(request->id_num); 168 /* insert a new entry into the top of the list */ 169 ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY)); 170 if (ptr == NULL) { 171 syslog(LOG_ERR, "insert_table: Out of memory"); 172 _exit(1); 173 } 174 ptr->time = current_time; 175 ptr->request = *request; 176 TAILQ_INSERT_HEAD(&table, ptr, list); 177 } 178 179 /* 180 * Generate a unique non-zero sequence number 181 */ 182 int 183 new_id(void) 184 { 185 static int 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 int 198 delete_invite(int id_num) 199 { 200 TABLE_ENTRY *ptr; 201 202 if (debug) 203 syslog(LOG_DEBUG, "delete_invite(%d)", id_num); 204 TAILQ_FOREACH(ptr, &table, list) { 205 if (ptr->request.id_num == id_num) 206 break; 207 if (debug) 208 print_request("", &ptr->request); 209 } 210 if (ptr != NULL) { 211 delete(ptr); 212 return (SUCCESS); 213 } 214 return (NOT_HERE); 215 } 216 217 /* 218 * Classic delete from a double-linked list 219 */ 220 static void 221 delete(TABLE_ENTRY *ptr) 222 { 223 224 if (debug) 225 print_request("delete", &ptr->request); 226 TAILQ_REMOVE(&table, ptr, list); 227 free((char *)ptr); 228 } 229