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table.c revision 1.10 
      1 /*	$NetBSD: table.c,v 1.10 2009/03/16 01:13:38 lukem Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1983, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #ifndef lint
     34 #if 0
     35 static char sccsid[] = "@(#)table.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: table.c,v 1.10 2009/03/16 01:13:38 lukem Exp $");
     38 #endif
     39 #endif /* not lint */
     40 
     41 /*
     42  * Routines to handle insertion, deletion, etc on the table
     43  * of requests kept by the daemon. Nothing fancy here, linear
     44  * search on a double-linked list. A time is kept with each
     45  * entry so that overly old invitations can be eliminated.
     46  *
     47  * Consider this a mis-guided attempt at modularity
     48  */
     49 #include <sys/param.h>
     50 #include <sys/time.h>
     51 #include <sys/socket.h>
     52 #include <protocols/talkd.h>
     53 #include <inttypes.h>
     54 #include <syslog.h>
     55 #include <unistd.h>
     56 #include <stdio.h>
     57 #include <stdlib.h>
     58 #include <string.h>
     59 #include "extern.h"
     60 
     61 #define MAX_ID 16000	/* << 2^15 so I don't have sign troubles */
     62 
     63 #define NIL ((TABLE_ENTRY *)0)
     64 
     65 struct	timeval tp;
     66 
     67 typedef struct table_entry TABLE_ENTRY;
     68 
     69 struct table_entry {
     70 	CTL_MSG request;
     71 	time_t	time;
     72 	TABLE_ENTRY *next;
     73 	TABLE_ENTRY *last;
     74 };
     75 
     76 TABLE_ENTRY *table = NIL;
     77 
     78 static void delete(TABLE_ENTRY *);
     79 
     80 /*
     81  * Look in the table for an invitation that matches the current
     82  * request looking for an invitation
     83  */
     84 CTL_MSG *
     85 find_match(CTL_MSG *request)
     86 {
     87 	TABLE_ENTRY *ptr;
     88 	time_t current_time;
     89 
     90 	gettimeofday(&tp, NULL);
     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  */
    117 CTL_MSG *
    118 find_request(CTL_MSG *request)
    119 {
    120 	TABLE_ENTRY *ptr;
    121 	time_t current_time;
    122 
    123 	gettimeofday(&tp, NULL);
    124 	current_time = tp.tv_sec;
    125 	/*
    126 	 * See if this is a repeated message, and check for
    127 	 * out of date entries in the table while we are it.
    128 	 */
    129 	if (debug)
    130 		print_request("find_request", request);
    131 	for (ptr = table; ptr != NIL; ptr = ptr->next) {
    132 		if ((ptr->time - current_time) > MAX_LIFE) {
    133 			/* the entry is too old */
    134 			if (debug)
    135 				print_request("deleting expired entry",
    136 				    &ptr->request);
    137 			delete(ptr);
    138 			continue;
    139 		}
    140 		if (debug)
    141 			print_request("", &ptr->request);
    142 		if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
    143 		    strcmp(request->l_name, ptr->request.l_name) == 0 &&
    144 		    request->type == ptr->request.type &&
    145 		    request->pid == ptr->request.pid) {
    146 			/* update the time if we 'touch' it */
    147 			ptr->time = current_time;
    148 			return (&ptr->request);
    149 		}
    150 	}
    151 	return ((CTL_MSG *)0);
    152 }
    153 
    154 void
    155 insert_table(CTL_MSG *request, CTL_RESPONSE *response)
    156 {
    157 	TABLE_ENTRY *ptr;
    158 	time_t current_time;
    159 
    160 	gettimeofday(&tp, NULL);
    161 	current_time = tp.tv_sec;
    162 	request->id_num = new_id();
    163 	response->id_num = htonl(request->id_num);
    164 	/* insert a new entry into the top of the list */
    165 	ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
    166 	if (ptr == NIL) {
    167 		syslog(LOG_ERR, "insert_table: Out of memory");
    168 		_exit(1);
    169 	}
    170 	ptr->time = current_time;
    171 	ptr->request = *request;
    172 	ptr->next = table;
    173 	if (ptr->next != NIL)
    174 		ptr->next->last = ptr;
    175 	ptr->last = NIL;
    176 	table = ptr;
    177 }
    178 
    179 /*
    180  * Generate a unique non-zero sequence number
    181  */
    182 uint32_t
    183 new_id(void)
    184 {
    185 	static uint32_t current_id = 0;
    186 
    187 	current_id = (current_id + 1) % MAX_ID;
    188 	/* 0 is reserved, helps to pick up bugs */
    189 	if (current_id == 0)
    190 		current_id = 1;
    191 	return (current_id);
    192 }
    193 
    194 /*
    195  * Delete the invitation with id 'id_num'
    196  */
    197 u_char
    198 delete_invite(uint32_t id_num)
    199 {
    200 	TABLE_ENTRY *ptr;
    201 
    202 	ptr = table;
    203 	if (debug)
    204 		syslog(LOG_DEBUG, "delete_invite(%"PRIu32")", id_num);
    205 	for (ptr = table; ptr != NIL; ptr = ptr->next) {
    206 		if (ptr->request.id_num == id_num)
    207 			break;
    208 		if (debug)
    209 			print_request("", &ptr->request);
    210 	}
    211 	if (ptr != NIL) {
    212 		delete(ptr);
    213 		return (SUCCESS);
    214 	}
    215 	return (NOT_HERE);
    216 }
    217 
    218 /*
    219  * Classic delete from a double-linked list
    220  */
    221 static void
    222 delete(TABLE_ENTRY *ptr)
    223 {
    224 
    225 	if (debug)
    226 		print_request("delete", &ptr->request);
    227 	if (table == ptr)
    228 		table = ptr->next;
    229 	else if (ptr->last != NIL)
    230 		ptr->last->next = ptr->next;
    231 	if (ptr->next != NIL)
    232 		ptr->next->last = ptr->last;
    233 	free((char *)ptr);
    234 }
    235