table.c revision 262435 
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. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#ifndef lint
31#if 0
32static char sccsid[] = "@(#)table.c	8.1 (Berkeley) 6/4/93";
33#endif
34static const char rcsid[] =
35  "$FreeBSD: stable/10/libexec/talkd/table.c 262435 2014-02-24 08:21:49Z brueffer $";
36#endif /* not lint */
37
38/*
39 * Routines to handle insertion, deletion, etc on the table
40 * of requests kept by the daemon. Nothing fancy here, linear
41 * search on a double-linked list. A time is kept with each
42 * entry so that overly old invitations can be eliminated.
43 *
44 * Consider this a mis-guided attempt at modularity
45 */
46#include <sys/param.h>
47#include <sys/time.h>
48#include <sys/socket.h>
49#include <netinet/in.h>
50#include <protocols/talkd.h>
51#include <stdio.h>
52#include <stdlib.h>
53#include <string.h>
54#include <syslog.h>
55#include <unistd.h>
56
57#include "extern.h"
58
59#define MAX_ID 16000	/* << 2^15 so I don't have sign troubles */
60
61#define NIL ((TABLE_ENTRY *)0)
62
63static struct timeval tp;
64
65typedef struct table_entry TABLE_ENTRY;
66
67struct table_entry {
68	CTL_MSG request;
69	long	time;
70	TABLE_ENTRY *next;
71	TABLE_ENTRY *last;
72};
73
74static void delete(TABLE_ENTRY *);
75
76static TABLE_ENTRY *table = NIL;
77
78/*
79 * Look in the table for an invitation that matches the current
80 * request looking for an invitation
81 */
82CTL_MSG *
83find_match(CTL_MSG *request)
84{
85	TABLE_ENTRY *ptr;
86	time_t current_time;
87
88	gettimeofday(&tp, NULL);
89	current_time = tp.tv_sec;
90	if (debug)
91		print_request("find_match", request);
92	for (ptr = table; ptr != NIL; ptr = ptr->next) {
93		if ((ptr->time - current_time) > MAX_LIFE) {
94			/* the entry is too old */
95			if (debug)
96				print_request("deleting expired entry",
97				    &ptr->request);
98			delete(ptr);
99			continue;
100		}
101		if (debug)
102			print_request("", &ptr->request);
103		if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
104		    strcmp(request->r_name, ptr->request.l_name) == 0 &&
105		     ptr->request.type == LEAVE_INVITE)
106			return (&ptr->request);
107	}
108	return ((CTL_MSG *)0);
109}
110
111/*
112 * Look for an identical request, as opposed to a complimentary
113 * one as find_match does
114 */
115CTL_MSG *
116find_request(CTL_MSG *request)
117{
118	TABLE_ENTRY *ptr;
119	time_t current_time;
120
121	gettimeofday(&tp, NULL);
122	current_time = tp.tv_sec;
123	/*
124	 * See if this is a repeated message, and check for
125	 * out of date entries in the table while we are it.
126	 */
127	if (debug)
128		print_request("find_request", request);
129	for (ptr = table; ptr != NIL; ptr = ptr->next) {
130		if ((ptr->time - current_time) > MAX_LIFE) {
131			/* the entry is too old */
132			if (debug)
133				print_request("deleting expired entry",
134				    &ptr->request);
135			delete(ptr);
136			continue;
137		}
138		if (debug)
139			print_request("", &ptr->request);
140		if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
141		    strcmp(request->l_name, ptr->request.l_name) == 0 &&
142		    request->type == ptr->request.type &&
143		    request->pid == ptr->request.pid) {
144			/* update the time if we 'touch' it */
145			ptr->time = current_time;
146			return (&ptr->request);
147		}
148	}
149	return ((CTL_MSG *)0);
150}
151
152void
153insert_table(CTL_MSG *request, CTL_RESPONSE *response)
154{
155	TABLE_ENTRY *ptr;
156	time_t current_time;
157
158	gettimeofday(&tp, NULL);
159	current_time = tp.tv_sec;
160	request->id_num = new_id();
161	response->id_num = htonl(request->id_num);
162	/* insert a new entry into the top of the list */
163	ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
164	if (ptr == NIL) {
165		syslog(LOG_ERR, "insert_table: Out of memory");
166		_exit(1);
167	}
168	ptr->time = current_time;
169	ptr->request = *request;
170	ptr->next = table;
171	if (ptr->next != NIL)
172		ptr->next->last = ptr;
173	ptr->last = NIL;
174	table = ptr;
175}
176
177/*
178 * Generate a unique non-zero sequence number
179 */
180int
181new_id(void)
182{
183	static int current_id = 0;
184
185	current_id = (current_id + 1) % MAX_ID;
186	/* 0 is reserved, helps to pick up bugs */
187	if (current_id == 0)
188		current_id = 1;
189	return (current_id);
190}
191
192/*
193 * Delete the invitation with id 'id_num'
194 */
195int
196delete_invite(u_int32_t id_num)
197{
198	TABLE_ENTRY *ptr;
199
200	ptr = table;
201	if (debug)
202		syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
203	for (ptr = table; ptr != NIL; ptr = ptr->next) {
204		if (ptr->request.id_num == id_num)
205			break;
206		if (debug)
207			print_request("", &ptr->request);
208	}
209	if (ptr != NIL) {
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	if (table == ptr)
226		table = ptr->next;
227	else if (ptr->last != NIL)
228		ptr->last->next = ptr->next;
229	if (ptr->next != NIL)
230		ptr->next->last = ptr->last;
231	free((char *)ptr);
232}
233