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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)table.c 8.1 (Berkeley) 6/4/93 34 * $FreeBSD: src/libexec/talkd/table.c,v 1.7 1999/08/28 00:10:17 peter Exp $ 35 */ 36 37 /* 38 * Routines to handle insertion, deletion, etc on the table 39 * of requests kept by the daemon. Nothing fancy here, linear 40 * search on a double-linked list. A time is kept with each 41 * entry so that overly old invitations can be eliminated. 42 * 43 * Consider this a mis-guided attempt at modularity 44 */ 45 #include <sys/param.h> 46 #include <sys/time.h> 47 #include <sys/socket.h> 48 #include <protocols/talkd.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <syslog.h> 53 #include <unistd.h> 54 55 #include "extern.h" 56 57 #define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */ 58 59 extern int debug; 60 struct timeval tp; 61 62 typedef struct table_entry TABLE_ENTRY; 63 64 struct table_entry { 65 CTL_MSG request; 66 long time; 67 TABLE_ENTRY *next; 68 TABLE_ENTRY *last; 69 }; 70 71 static void delete(TABLE_ENTRY *); 72 73 TABLE_ENTRY *table = NULL; 74 75 /* 76 * Look in the table for an invitation that matches the current 77 * request looking for an invitation 78 */ 79 CTL_MSG * 80 find_match(CTL_MSG *request) 81 { 82 TABLE_ENTRY *ptr; 83 time_t current_time; 84 85 gettimeofday(&tp, NULL); 86 current_time = tp.tv_sec; 87 if (debug) 88 print_request("find_match", request); 89 for (ptr = table; ptr != NULL; ptr = ptr->next) { 90 if ((ptr->time - current_time) > MAX_LIFE) { 91 /* the entry is too old */ 92 if (debug) 93 print_request("deleting expired entry", 94 &ptr->request); 95 delete(ptr); 96 continue; 97 } 98 if (debug) 99 print_request("", &ptr->request); 100 if (strcmp(request->l_name, ptr->request.r_name) == 0 && 101 strcmp(request->r_name, ptr->request.l_name) == 0 && 102 ptr->request.type == LEAVE_INVITE) 103 return (&ptr->request); 104 } 105 return (NULL); 106 } 107 108 /* 109 * Look for an identical request, as opposed to a complimentary 110 * one as find_match does 111 */ 112 CTL_MSG * 113 find_request(CTL_MSG *request) 114 { 115 TABLE_ENTRY *ptr; 116 time_t current_time; 117 118 gettimeofday(&tp, NULL); 119 current_time = tp.tv_sec; 120 /* 121 * See if this is a repeated message, and check for 122 * out of date entries in the table while we are it. 123 */ 124 if (debug) 125 print_request("find_request", request); 126 for (ptr = table; ptr != NULL; ptr = ptr->next) { 127 if ((ptr->time - current_time) > MAX_LIFE) { 128 /* the entry is too old */ 129 if (debug) 130 print_request("deleting expired entry", 131 &ptr->request); 132 delete(ptr); 133 continue; 134 } 135 if (debug) 136 print_request("", &ptr->request); 137 if (strcmp(request->r_name, ptr->request.r_name) == 0 && 138 strcmp(request->l_name, ptr->request.l_name) == 0 && 139 request->type == ptr->request.type && 140 request->pid == ptr->request.pid) { 141 /* update the time if we 'touch' it */ 142 ptr->time = current_time; 143 return (&ptr->request); 144 } 145 } 146 return (NULL); 147 } 148 149 void 150 insert_table(CTL_MSG *request, CTL_RESPONSE *response) 151 { 152 TABLE_ENTRY *ptr; 153 time_t current_time; 154 155 gettimeofday(&tp, NULL); 156 current_time = tp.tv_sec; 157 request->id_num = new_id(); 158 response->id_num = htonl(request->id_num); 159 /* insert a new entry into the top of the list */ 160 ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY)); 161 if (ptr == NULL) { 162 syslog(LOG_ERR, "insert_table: Out of memory"); 163 _exit(1); 164 } 165 ptr->time = current_time; 166 ptr->request = *request; 167 ptr->next = table; 168 if (ptr->next != NULL) 169 ptr->next->last = ptr; 170 ptr->last = NULL; 171 table = ptr; 172 } 173 174 /* 175 * Generate a unique non-zero sequence number 176 */ 177 int 178 new_id(void) 179 { 180 static int current_id = 0; 181 182 current_id = (current_id + 1) % MAX_ID; 183 /* 0 is reserved, helps to pick up bugs */ 184 if (current_id == 0) 185 current_id = 1; 186 return (current_id); 187 } 188 189 /* 190 * Delete the invitation with id 'id_num' 191 */ 192 int 193 delete_invite(unsigned int id_num) 194 { 195 TABLE_ENTRY *ptr; 196 197 ptr = table; 198 if (debug) 199 syslog(LOG_DEBUG, "delete_invite(%d)", id_num); 200 for (ptr = table; ptr != NULL; ptr = ptr->next) { 201 if (ptr->request.id_num == id_num) 202 break; 203 if (debug) 204 print_request("", &ptr->request); 205 } 206 if (ptr != NULL) { 207 delete(ptr); 208 return (SUCCESS); 209 } 210 return (NOT_HERE); 211 } 212 213 /* 214 * Classic delete from a double-linked list 215 */ 216 static void 217 delete(TABLE_ENTRY *ptr) 218 { 219 220 if (debug) 221 print_request("delete", &ptr->request); 222 if (table == ptr) 223 table = ptr->next; 224 else if (ptr->last != NULL) 225 ptr->last->next = ptr->next; 226 if (ptr->next != NULL) 227 ptr->next->last = ptr->last; 228 free((char *)ptr); 229 } 230