1/*	$OpenBSD: table.c,v 1.20 2019/08/09 22:52:13 cheloha Exp $	*/
2
3/*
4 * Copyright (c) 1983 Regents of the University of California.
5 * 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/*
33 * Routines to handle insertion, deletion, etc on the table
34 * of requests kept by the daemon. Nothing fancy here, linear
35 * search on a double-linked list. A time is kept with each
36 * entry so that overly old invitations can be eliminated.
37 *
38 * Consider this a mis-guided attempt at modularity
39 */
40#include <sys/queue.h>
41#include <sys/socket.h>
42#include <sys/time.h>
43#include <protocols/talkd.h>
44
45#include <stdlib.h>
46#include <string.h>
47#include <syslog.h>
48#include <unistd.h>
49
50#include "talkd.h"
51
52#define MAX_ID 16000	/* << 2^15 so I don't have sign troubles */
53
54struct	timeval tp;
55
56typedef struct table_entry TABLE_ENTRY;
57
58struct table_entry {
59	CTL_MSG request;
60	time_t	time;
61	TAILQ_ENTRY(table_entry) list;
62};
63TAILQ_HEAD(, table_entry)	table;
64
65static void	delete(TABLE_ENTRY *);
66
67/*
68 * Init the table
69 */
70void
71init_table(void)
72{
73	TAILQ_INIT(&table);
74}
75
76/*
77 * Look in the table for an invitation that matches the current
78 * request looking for an invitation
79 */
80CTL_MSG *
81find_match(CTL_MSG *request)
82{
83	TABLE_ENTRY *ptr, *next;
84	time_t current_time;
85
86	gettimeofday(&tp, NULL);
87	current_time = tp.tv_sec;
88	if (debug)
89		print_request("find_match", request);
90	for (ptr = TAILQ_FIRST(&table); ptr != NULL; ptr = next) {
91		next = TAILQ_NEXT(ptr, list);
92		if ((current_time - ptr->time) > MAX_LIFE) {
93			/* the entry is too old */
94			if (debug)
95				print_request("deleting expired entry",
96				    &ptr->request);
97			delete(ptr);
98			continue;
99		}
100		if (debug)
101			print_request("", &ptr->request);
102		if (ptr->request.type == LEAVE_INVITE &&
103		    strcmp(request->l_name, ptr->request.r_name) == 0 &&
104		    strcmp(request->r_name, ptr->request.l_name) == 0)
105			return (&ptr->request);
106	}
107	if (debug)
108		syslog(LOG_DEBUG, "find_match: not found");
109
110	return (NULL);
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(CTL_MSG *request)
119{
120	TABLE_ENTRY *ptr, *next;
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 = TAILQ_FIRST(&table); ptr != NULL; ptr = next) {
132		next = TAILQ_NEXT(ptr, list);
133		if ((current_time - ptr->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 (request->pid == ptr->request.pid &&
144		    request->type == ptr->request.type &&
145		    strcmp(request->r_name, ptr->request.r_name) == 0 &&
146		    strcmp(request->l_name, ptr->request.l_name) == 0) {
147			/* update the time if we 'touch' it */
148			ptr->time = current_time;
149			return (&ptr->request);
150		}
151	}
152	return (NULL);
153}
154
155void
156insert_table(CTL_MSG *request, CTL_RESPONSE *response)
157{
158	TABLE_ENTRY *ptr;
159	time_t current_time;
160
161	if (debug)
162		print_request( "insert_table", request );
163	gettimeofday(&tp, NULL);
164	current_time = tp.tv_sec;
165	request->id_num = new_id();
166	response->id_num = htonl(request->id_num);
167	/* insert a new entry into the top of the list */
168	ptr = malloc(sizeof(TABLE_ENTRY));
169	if (ptr == NULL) {
170		syslog(LOG_ERR, "insert_table: Out of memory");
171		_exit(1);
172	}
173	ptr->time = current_time;
174	ptr->request = *request;
175	TAILQ_INSERT_HEAD(&table, ptr, list);
176}
177
178/*
179 * Generate a unique non-zero sequence number
180 */
181int
182new_id(void)
183{
184	static int current_id = 0;
185
186	current_id = (current_id + 1) % MAX_ID;
187	/* 0 is reserved, helps to pick up bugs */
188	if (current_id == 0)
189		current_id = 1;
190	return (current_id);
191}
192
193/*
194 * Delete the invitation with id 'id_num'
195 */
196int
197delete_invite(int id_num)
198{
199	TABLE_ENTRY *ptr;
200
201	if (debug)
202		syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
203	TAILQ_FOREACH(ptr, &table, list) {
204		if (ptr->request.id_num == id_num)
205			break;
206		if (debug)
207			print_request("", &ptr->request);
208	}
209	if (ptr != NULL) {
210		delete(ptr);
211		return (SUCCESS);
212	}
213	return (NOT_HERE);
214}
215
216/*
217 * Classic delete from a double-linked list
218 */
219static void
220delete(TABLE_ENTRY *ptr)
221{
222
223	if (debug)
224		print_request("delete", &ptr->request);
225	TAILQ_REMOVE(&table, ptr, list);
226	free((char *)ptr);
227}
228