table.c revision 241777
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 241777 2012-10-20 10:33:15Z ed $"; 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 <netinet/in.h> 54#include <protocols/talkd.h> 55#include <stdio.h> 56#include <stdlib.h> 57#include <string.h> 58#include <syslog.h> 59#include <unistd.h> 60 61#include "extern.h" 62 63#define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */ 64 65#define NIL ((TABLE_ENTRY *)0) 66 67static struct timeval tp; 68 69typedef struct table_entry TABLE_ENTRY; 70 71struct table_entry { 72 CTL_MSG request; 73 long time; 74 TABLE_ENTRY *next; 75 TABLE_ENTRY *last; 76}; 77 78static void delete(TABLE_ENTRY *); 79 80static TABLE_ENTRY *table = NIL; 81 82/* 83 * Look in the table for an invitation that matches the current 84 * request looking for an invitation 85 */ 86CTL_MSG * 87find_match(CTL_MSG *request) 88{ 89 TABLE_ENTRY *ptr; 90 time_t current_time; 91 92 gettimeofday(&tp, NULL); 93 current_time = tp.tv_sec; 94 if (debug) 95 print_request("find_match", request); 96 for (ptr = table; ptr != NIL; ptr = ptr->next) { 97 if ((ptr->time - current_time) > MAX_LIFE) { 98 /* the entry is too old */ 99 if (debug) 100 print_request("deleting expired entry", 101 &ptr->request); 102 delete(ptr); 103 continue; 104 } 105 if (debug) 106 print_request("", &ptr->request); 107 if (strcmp(request->l_name, ptr->request.r_name) == 0 && 108 strcmp(request->r_name, ptr->request.l_name) == 0 && 109 ptr->request.type == LEAVE_INVITE) 110 return (&ptr->request); 111 } 112 return ((CTL_MSG *)0); 113} 114 115/* 116 * Look for an identical request, as opposed to a complimentary 117 * one as find_match does 118 */ 119CTL_MSG * 120find_request(CTL_MSG *request) 121{ 122 TABLE_ENTRY *ptr; 123 time_t current_time; 124 125 gettimeofday(&tp, NULL); 126 current_time = tp.tv_sec; 127 /* 128 * See if this is a repeated message, and check for 129 * out of date entries in the table while we are it. 130 */ 131 if (debug) 132 print_request("find_request", request); 133 for (ptr = table; ptr != NIL; ptr = ptr->next) { 134 if ((ptr->time - current_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 (strcmp(request->r_name, ptr->request.r_name) == 0 && 145 strcmp(request->l_name, ptr->request.l_name) == 0 && 146 request->type == ptr->request.type && 147 request->pid == ptr->request.pid) { 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 156void 157insert_table(CTL_MSG *request, CTL_RESPONSE *response) 158{ 159 TABLE_ENTRY *ptr; 160 time_t current_time; 161 162 gettimeofday(&tp, NULL); 163 current_time = tp.tv_sec; 164 request->id_num = new_id(); 165 response->id_num = htonl(request->id_num); 166 /* insert a new entry into the top of the list */ 167 ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY)); 168 if (ptr == NIL) { 169 syslog(LOG_ERR, "insert_table: Out of memory"); 170 _exit(1); 171 } 172 ptr->time = current_time; 173 ptr->request = *request; 174 ptr->next = table; 175 if (ptr->next != NIL) 176 ptr->next->last = ptr; 177 ptr->last = NIL; 178 table = ptr; 179} 180 181/* 182 * Generate a unique non-zero sequence number 183 */ 184int 185new_id(void) 186{ 187 static int current_id = 0; 188 189 current_id = (current_id + 1) % MAX_ID; 190 /* 0 is reserved, helps to pick up bugs */ 191 if (current_id == 0) 192 current_id = 1; 193 return (current_id); 194} 195 196/* 197 * Delete the invitation with id 'id_num' 198 */ 199int 200delete_invite(u_int32_t id_num) 201{ 202 TABLE_ENTRY *ptr; 203 204 ptr = table; 205 if (debug) 206 syslog(LOG_DEBUG, "delete_invite(%d)", id_num); 207 for (ptr = table; ptr != NIL; ptr = ptr->next) { 208 if (ptr->request.id_num == id_num) 209 break; 210 if (debug) 211 print_request("", &ptr->request); 212 } 213 if (ptr != NIL) { 214 delete(ptr); 215 return (SUCCESS); 216 } 217 return (NOT_HERE); 218} 219 220/* 221 * Classic delete from a double-linked list 222 */ 223static void 224delete(TABLE_ENTRY *ptr) 225{ 226 227 if (debug) 228 print_request("delete", &ptr->request); 229 if (table == ptr) 230 table = ptr->next; 231 else if (ptr->last != NIL) 232 ptr->last->next = ptr->next; 233 if (ptr->next != NIL) 234 ptr->next->last = ptr->last; 235 free((char *)ptr); 236} 237