table.c revision 22989
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 * $Id$ 34 */ 35 36#ifndef lint 37static char sccsid[] = "@(#)table.c 8.1 (Berkeley) 6/4/93"; 38#endif /* not lint */ 39 40/* 41 * Routines to handle insertion, deletion, etc on the table 42 * of requests kept by the daemon. Nothing fancy here, linear 43 * search on a double-linked list. A time is kept with each 44 * entry so that overly old invitations can be eliminated. 45 * 46 * Consider this a mis-guided attempt at modularity 47 */ 48#include <sys/param.h> 49#include <sys/time.h> 50#include <sys/socket.h> 51#include <protocols/talkd.h> 52#include <syslog.h> 53#include <unistd.h> 54#include <stdio.h> 55#include <stdlib.h> 56#include <string.h> 57 58#define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */ 59 60#define NIL ((TABLE_ENTRY *)0) 61 62extern int debug; 63struct timeval tp; 64struct timezone txp; 65 66typedef struct table_entry TABLE_ENTRY; 67 68struct table_entry { 69 CTL_MSG request; 70 long time; 71 TABLE_ENTRY *next; 72 TABLE_ENTRY *last; 73}; 74 75TABLE_ENTRY *table = NIL; 76CTL_MSG *find_request(); 77CTL_MSG *find_match(); 78 79/* 80 * Look in the table for an invitation that matches the current 81 * request looking for an invitation 82 */ 83CTL_MSG * 84find_match(request) 85 register CTL_MSG *request; 86{ 87 register TABLE_ENTRY *ptr; 88 time_t current_time; 89 90 gettimeofday(&tp, &txp); 91 current_time = tp.tv_sec; 92 if (debug) 93 print_request("find_match", request); 94 for (ptr = table; ptr != NIL; ptr = ptr->next) { 95 if ((ptr->time - current_time) > MAX_LIFE) { 96 /* the entry is too old */ 97 if (debug) 98 print_request("deleting expired entry", 99 &ptr->request); 100 delete(ptr); 101 continue; 102 } 103 if (debug) 104 print_request("", &ptr->request); 105 if (strcmp(request->l_name, ptr->request.r_name) == 0 && 106 strcmp(request->r_name, ptr->request.l_name) == 0 && 107 ptr->request.type == LEAVE_INVITE) 108 return (&ptr->request); 109 } 110 return ((CTL_MSG *)0); 111} 112 113/* 114 * Look for an identical request, as opposed to a complimentary 115 * one as find_match does 116 */ 117CTL_MSG * 118find_request(request) 119 register CTL_MSG *request; 120{ 121 register TABLE_ENTRY *ptr; 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 = table; ptr != NIL; ptr = ptr->next) { 133 if ((ptr->time - current_time) > MAX_LIFE) { 134 /* the entry is too old */ 135 if (debug) 136 print_request("deleting expired entry", 137 &ptr->request); 138 delete(ptr); 139 continue; 140 } 141 if (debug) 142 print_request("", &ptr->request); 143 if (strcmp(request->r_name, ptr->request.r_name) == 0 && 144 strcmp(request->l_name, ptr->request.l_name) == 0 && 145 request->type == ptr->request.type && 146 request->pid == ptr->request.pid) { 147 /* update the time if we 'touch' it */ 148 ptr->time = current_time; 149 return (&ptr->request); 150 } 151 } 152 return ((CTL_MSG *)0); 153} 154 155insert_table(request, response) 156 CTL_MSG *request; 157 CTL_RESPONSE *response; 158{ 159 register TABLE_ENTRY *ptr; 160 time_t current_time; 161 162 gettimeofday(&tp, &txp); 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 */ 184new_id() 185{ 186 static int current_id = 0; 187 188 current_id = (current_id + 1) % MAX_ID; 189 /* 0 is reserved, helps to pick up bugs */ 190 if (current_id == 0) 191 current_id = 1; 192 return (current_id); 193} 194 195/* 196 * Delete the invitation with id 'id_num' 197 */ 198delete_invite(id_num) 199 int id_num; 200{ 201 register TABLE_ENTRY *ptr; 202 203 ptr = table; 204 if (debug) 205 syslog(LOG_DEBUG, "delete_invite(%d)", id_num); 206 for (ptr = table; ptr != NIL; ptr = ptr->next) { 207 if (ptr->request.id_num == id_num) 208 break; 209 if (debug) 210 print_request("", &ptr->request); 211 } 212 if (ptr != NIL) { 213 delete(ptr); 214 return (SUCCESS); 215 } 216 return (NOT_HERE); 217} 218 219/* 220 * Classic delete from a double-linked list 221 */ 222delete(ptr) 223 register TABLE_ENTRY *ptr; 224{ 225 226 if (debug) 227 print_request("delete", &ptr->request); 228 if (table == ptr) 229 table = ptr->next; 230 else if (ptr->last != NIL) 231 ptr->last->next = ptr->next; 232 if (ptr->next != NIL) 233 ptr->next->last = ptr->last; 234 free((char *)ptr); 235} 236