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/* $OpenBSD: table.c,v 1.15 2014/10/08 02:10:05 deraadt Exp $ */
/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Routines to handle insertion, deletion, etc on the table
* of requests kept by the daemon. Nothing fancy here, linear
* search on a double-linked list. A time is kept with each
* entry so that overly old invitations can be eliminated.
*
* Consider this a mis-guided attempt at modularity
*/
#include <sys/param.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/queue.h>
#include <protocols/talkd.h>
#include <syslog.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "talkd.h"
#define MAX_ID 16000 /* << 2^15 so I don't have sign troubles */
struct timeval tp;
struct timezone txp;
typedef struct table_entry TABLE_ENTRY;
struct table_entry {
CTL_MSG request;
time_t time;
TAILQ_ENTRY(table_entry) list;
};
TAILQ_HEAD(, table_entry) table;
static void delete(TABLE_ENTRY *);
/*
* Init the table
*/
void
init_table(void)
{
TAILQ_INIT(&table);
}
/*
* Look in the table for an invitation that matches the current
* request looking for an invitation
*/
CTL_MSG *
find_match(CTL_MSG *request)
{
TABLE_ENTRY *ptr, *next;
time_t current_time;
gettimeofday(&tp, &txp);
current_time = tp.tv_sec;
if (debug)
print_request("find_match", request);
for (ptr = TAILQ_FIRST(&table); ptr != NULL; ptr = next) {
next = TAILQ_NEXT(ptr, list);
if ((current_time - ptr->time) > MAX_LIFE) {
/* the entry is too old */
if (debug)
print_request("deleting expired entry",
&ptr->request);
delete(ptr);
continue;
}
if (debug)
print_request("", &ptr->request);
if (ptr->request.type == LEAVE_INVITE &&
strcmp(request->l_name, ptr->request.r_name) == 0 &&
strcmp(request->r_name, ptr->request.l_name) == 0)
return (&ptr->request);
}
if (debug)
syslog(LOG_DEBUG, "find_match: not found");
return ((CTL_MSG *)0);
}
/*
* Look for an identical request, as opposed to a complimentary
* one as find_match does
*/
CTL_MSG *
find_request(CTL_MSG *request)
{
TABLE_ENTRY *ptr, *next;
time_t current_time;
gettimeofday(&tp, &txp);
current_time = tp.tv_sec;
/*
* See if this is a repeated message, and check for
* out of date entries in the table while we are it.
*/
if (debug)
print_request("find_request", request);
for (ptr = TAILQ_FIRST(&table); ptr != NULL; ptr = next) {
next = TAILQ_NEXT(ptr, list);
if ((current_time - ptr->time) > MAX_LIFE) {
/* the entry is too old */
if (debug)
print_request("deleting expired entry",
&ptr->request);
delete(ptr);
continue;
}
if (debug)
print_request("", &ptr->request);
if (request->pid == ptr->request.pid &&
request->type == ptr->request.type &&
strcmp(request->r_name, ptr->request.r_name) == 0 &&
strcmp(request->l_name, ptr->request.l_name) == 0) {
/* update the time if we 'touch' it */
ptr->time = current_time;
return (&ptr->request);
}
}
return ((CTL_MSG *)0);
}
void
insert_table(CTL_MSG *request, CTL_RESPONSE *response)
{
TABLE_ENTRY *ptr;
time_t current_time;
if (debug)
print_request( "insert_table", request );
gettimeofday(&tp, &txp);
current_time = tp.tv_sec;
request->id_num = new_id();
response->id_num = htonl(request->id_num);
/* insert a new entry into the top of the list */
ptr = malloc(sizeof(TABLE_ENTRY));
if (ptr == NULL) {
syslog(LOG_ERR, "insert_table: Out of memory");
_exit(1);
}
ptr->time = current_time;
ptr->request = *request;
TAILQ_INSERT_HEAD(&table, ptr, list);
}
/*
* Generate a unique non-zero sequence number
*/
int
new_id(void)
{
static int current_id = 0;
current_id = (current_id + 1) % MAX_ID;
/* 0 is reserved, helps to pick up bugs */
if (current_id == 0)
current_id = 1;
return (current_id);
}
/*
* Delete the invitation with id 'id_num'
*/
int
delete_invite(int id_num)
{
TABLE_ENTRY *ptr;
if (debug)
syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
TAILQ_FOREACH(ptr, &table, list) {
if (ptr->request.id_num == id_num)
break;
if (debug)
print_request("", &ptr->request);
}
if (ptr != NULL) {
delete(ptr);
return (SUCCESS);
}
return (NOT_HERE);
}
/*
* Classic delete from a double-linked list
*/
static void
delete(TABLE_ENTRY *ptr)
{
if (debug)
print_request("delete", &ptr->request);
TAILQ_REMOVE(&table, ptr, list);
free((char *)ptr);
}
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