table.c revision 90261
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 34#ifndef lint 35#if 0 36static char sccsid[] = "@(#)table.c 8.1 (Berkeley) 6/4/93"; 37#endif 38static const char rcsid[] = 39 "$FreeBSD: head/libexec/talkd/table.c 90261 2002-02-05 21:06:56Z imp $"; 40#endif /* not lint */ 41 42/* 43 * Routines to handle insertion, deletion, etc on the table 44 * of requests kept by the daemon. Nothing fancy here, linear 45 * search on a double-linked list. A time is kept with each 46 * entry so that overly old invitations can be eliminated. 47 * 48 * Consider this a mis-guided attempt at modularity 49 */ 50#include <sys/param.h> 51#include <sys/time.h> 52#include <sys/socket.h> 53#include <protocols/talkd.h> 54#include <stdio.h> 55#include <stdlib.h> 56#include <string.h> 57#include <syslog.h> 58#include <unistd.h> 59 60#include "extern.h" 61 62#define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */ 63 64#define NIL ((TABLE_ENTRY *)0) 65 66extern int debug; 67struct timeval tp; 68struct timezone txp; 69 70typedef struct table_entry TABLE_ENTRY; 71 72struct table_entry { 73 CTL_MSG request; 74 long time; 75 TABLE_ENTRY *next; 76 TABLE_ENTRY *last; 77}; 78 79static void delete(TABLE_ENTRY *); 80 81TABLE_ENTRY *table = NIL; 82 83/* 84 * Look in the table for an invitation that matches the current 85 * request looking for an invitation 86 */ 87CTL_MSG * 88find_match(CTL_MSG *request) 89{ 90 TABLE_ENTRY *ptr; 91 time_t current_time; 92 93 gettimeofday(&tp, &txp); 94 current_time = tp.tv_sec; 95 if (debug) 96 print_request("find_match", request); 97 for (ptr = table; ptr != NIL; ptr = ptr->next) { 98 if ((ptr->time - current_time) > MAX_LIFE) { 99 /* the entry is too old */ 100 if (debug) 101 print_request("deleting expired entry", 102 &ptr->request); 103 delete(ptr); 104 continue; 105 } 106 if (debug) 107 print_request("", &ptr->request); 108 if (strcmp(request->l_name, ptr->request.r_name) == 0 && 109 strcmp(request->r_name, ptr->request.l_name) == 0 && 110 ptr->request.type == LEAVE_INVITE) 111 return (&ptr->request); 112 } 113 return ((CTL_MSG *)0); 114} 115 116/* 117 * Look for an identical request, as opposed to a complimentary 118 * one as find_match does 119 */ 120CTL_MSG * 121find_request(CTL_MSG *request) 122{ 123 TABLE_ENTRY *ptr; 124 time_t current_time; 125 126 gettimeofday(&tp, &txp); 127 current_time = tp.tv_sec; 128 /* 129 * See if this is a repeated message, and check for 130 * out of date entries in the table while we are it. 131 */ 132 if (debug) 133 print_request("find_request", request); 134 for (ptr = table; ptr != NIL; ptr = ptr->next) { 135 if ((ptr->time - current_time) > MAX_LIFE) { 136 /* the entry is too old */ 137 if (debug) 138 print_request("deleting expired entry", 139 &ptr->request); 140 delete(ptr); 141 continue; 142 } 143 if (debug) 144 print_request("", &ptr->request); 145 if (strcmp(request->r_name, ptr->request.r_name) == 0 && 146 strcmp(request->l_name, ptr->request.l_name) == 0 && 147 request->type == ptr->request.type && 148 request->pid == ptr->request.pid) { 149 /* update the time if we 'touch' it */ 150 ptr->time = current_time; 151 return (&ptr->request); 152 } 153 } 154 return ((CTL_MSG *)0); 155} 156 157void 158insert_table(CTL_MSG *request, CTL_RESPONSE *response) 159{ 160 TABLE_ENTRY *ptr; 161 time_t current_time; 162 163 gettimeofday(&tp, &txp); 164 current_time = tp.tv_sec; 165 request->id_num = new_id(); 166 response->id_num = htonl(request->id_num); 167 /* insert a new entry into the top of the list */ 168 ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY)); 169 if (ptr == NIL) { 170 syslog(LOG_ERR, "insert_table: Out of memory"); 171 _exit(1); 172 } 173 ptr->time = current_time; 174 ptr->request = *request; 175 ptr->next = table; 176 if (ptr->next != NIL) 177 ptr->next->last = ptr; 178 ptr->last = NIL; 179 table = ptr; 180} 181 182/* 183 * Generate a unique non-zero sequence number 184 */ 185int 186new_id(void) 187{ 188 static int current_id = 0; 189 190 current_id = (current_id + 1) % MAX_ID; 191 /* 0 is reserved, helps to pick up bugs */ 192 if (current_id == 0) 193 current_id = 1; 194 return (current_id); 195} 196 197/* 198 * Delete the invitation with id 'id_num' 199 */ 200int 201delete_invite(int id_num) 202{ 203 TABLE_ENTRY *ptr; 204 205 ptr = table; 206 if (debug) 207 syslog(LOG_DEBUG, "delete_invite(%d)", id_num); 208 for (ptr = table; ptr != NIL; ptr = ptr->next) { 209 if (ptr->request.id_num == id_num) 210 break; 211 if (debug) 212 print_request("", &ptr->request); 213 } 214 if (ptr != NIL) { 215 delete(ptr); 216 return (SUCCESS); 217 } 218 return (NOT_HERE); 219} 220 221/* 222 * Classic delete from a double-linked list 223 */ 224static void 225delete(TABLE_ENTRY *ptr) 226{ 227 228 if (debug) 229 print_request("delete", &ptr->request); 230 if (table == ptr) 231 table = ptr->next; 232 else if (ptr->last != NIL) 233 ptr->last->next = ptr->next; 234 if (ptr->next != NIL) 235 ptr->next->last = ptr->last; 236 free((char *)ptr); 237} 238