table.c revision 31491
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 "$Id$"; 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#define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */ 61 62#define NIL ((TABLE_ENTRY *)0) 63 64extern int debug; 65struct timeval tp; 66struct timezone txp; 67 68typedef struct table_entry TABLE_ENTRY; 69 70struct table_entry { 71 CTL_MSG request; 72 long time; 73 TABLE_ENTRY *next; 74 TABLE_ENTRY *last; 75}; 76 77TABLE_ENTRY *table = NIL; 78 79void delete __P((TABLE_ENTRY *)); 80CTL_MSG *find_request(); 81CTL_MSG *find_match(); 82int new_id __P((void)); 83void print_request __P((char *, CTL_MSG *)); 84 85/* 86 * Look in the table for an invitation that matches the current 87 * request looking for an invitation 88 */ 89CTL_MSG * 90find_match(request) 91 register CTL_MSG *request; 92{ 93 register TABLE_ENTRY *ptr; 94 time_t current_time; 95 96 gettimeofday(&tp, &txp); 97 current_time = tp.tv_sec; 98 if (debug) 99 print_request("find_match", request); 100 for (ptr = table; ptr != NIL; ptr = ptr->next) { 101 if ((ptr->time - current_time) > MAX_LIFE) { 102 /* the entry is too old */ 103 if (debug) 104 print_request("deleting expired entry", 105 &ptr->request); 106 delete(ptr); 107 continue; 108 } 109 if (debug) 110 print_request("", &ptr->request); 111 if (strcmp(request->l_name, ptr->request.r_name) == 0 && 112 strcmp(request->r_name, ptr->request.l_name) == 0 && 113 ptr->request.type == LEAVE_INVITE) 114 return (&ptr->request); 115 } 116 return ((CTL_MSG *)0); 117} 118 119/* 120 * Look for an identical request, as opposed to a complimentary 121 * one as find_match does 122 */ 123CTL_MSG * 124find_request(request) 125 register CTL_MSG *request; 126{ 127 register TABLE_ENTRY *ptr; 128 time_t current_time; 129 130 gettimeofday(&tp, &txp); 131 current_time = tp.tv_sec; 132 /* 133 * See if this is a repeated message, and check for 134 * out of date entries in the table while we are it. 135 */ 136 if (debug) 137 print_request("find_request", request); 138 for (ptr = table; ptr != NIL; ptr = ptr->next) { 139 if ((ptr->time - current_time) > MAX_LIFE) { 140 /* the entry is too old */ 141 if (debug) 142 print_request("deleting expired entry", 143 &ptr->request); 144 delete(ptr); 145 continue; 146 } 147 if (debug) 148 print_request("", &ptr->request); 149 if (strcmp(request->r_name, ptr->request.r_name) == 0 && 150 strcmp(request->l_name, ptr->request.l_name) == 0 && 151 request->type == ptr->request.type && 152 request->pid == ptr->request.pid) { 153 /* update the time if we 'touch' it */ 154 ptr->time = current_time; 155 return (&ptr->request); 156 } 157 } 158 return ((CTL_MSG *)0); 159} 160 161void 162insert_table(request, response) 163 CTL_MSG *request; 164 CTL_RESPONSE *response; 165{ 166 register TABLE_ENTRY *ptr; 167 time_t current_time; 168 169 gettimeofday(&tp, &txp); 170 current_time = tp.tv_sec; 171 request->id_num = new_id(); 172 response->id_num = htonl(request->id_num); 173 /* insert a new entry into the top of the list */ 174 ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY)); 175 if (ptr == NIL) { 176 syslog(LOG_ERR, "insert_table: Out of memory"); 177 _exit(1); 178 } 179 ptr->time = current_time; 180 ptr->request = *request; 181 ptr->next = table; 182 if (ptr->next != NIL) 183 ptr->next->last = ptr; 184 ptr->last = NIL; 185 table = ptr; 186} 187 188/* 189 * Generate a unique non-zero sequence number 190 */ 191int 192new_id() 193{ 194 static int current_id = 0; 195 196 current_id = (current_id + 1) % MAX_ID; 197 /* 0 is reserved, helps to pick up bugs */ 198 if (current_id == 0) 199 current_id = 1; 200 return (current_id); 201} 202 203/* 204 * Delete the invitation with id 'id_num' 205 */ 206int 207delete_invite(id_num) 208 int id_num; 209{ 210 register TABLE_ENTRY *ptr; 211 212 ptr = table; 213 if (debug) 214 syslog(LOG_DEBUG, "delete_invite(%d)", id_num); 215 for (ptr = table; ptr != NIL; ptr = ptr->next) { 216 if (ptr->request.id_num == id_num) 217 break; 218 if (debug) 219 print_request("", &ptr->request); 220 } 221 if (ptr != NIL) { 222 delete(ptr); 223 return (SUCCESS); 224 } 225 return (NOT_HERE); 226} 227 228/* 229 * Classic delete from a double-linked list 230 */ 231void 232delete(ptr) 233 register TABLE_ENTRY *ptr; 234{ 235 236 if (debug) 237 print_request("delete", &ptr->request); 238 if (table == ptr) 239 table = ptr->next; 240 else if (ptr->last != NIL) 241 ptr->last->next = ptr->next; 242 if (ptr->next != NIL) 243 ptr->next->last = ptr->last; 244 free((char *)ptr); 245} 246