1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
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/*
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/param.h>
41#include <sys/time.h>
42#include <sys/socket.h>
43#include <netinet/in.h>
44#include <protocols/talkd.h>
45#include <stdio.h>
46#include <stdlib.h>
47#include <string.h>
48#include <syslog.h>
49#include <unistd.h>
50
51#include "extern.h"
52
53#define MAX_ID 16000	/* << 2^15 so I don't have sign troubles */
54
55#define NIL ((TABLE_ENTRY *)0)
56
57static struct timespec ts;
58
59typedef struct table_entry TABLE_ENTRY;
60
61struct table_entry {
62	CTL_MSG request;
63	long	time;
64	TABLE_ENTRY *next;
65	TABLE_ENTRY *last;
66};
67
68static void delete(TABLE_ENTRY *);
69
70static TABLE_ENTRY *table = NIL;
71
72/*
73 * Look in the table for an invitation that matches the current
74 * request looking for an invitation
75 */
76CTL_MSG *
77find_match(CTL_MSG *request)
78{
79	TABLE_ENTRY *ptr, *next;
80	time_t current_time;
81
82	clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
83	current_time = ts.tv_sec;
84	if (debug)
85		print_request("find_match", request);
86	for (ptr = table; ptr != NIL; ptr = next) {
87		next = ptr->next;
88		if ((ptr->time - current_time) > MAX_LIFE) {
89			/* the entry is too old */
90			if (debug)
91				print_request("deleting expired entry",
92				    &ptr->request);
93			delete(ptr);
94			continue;
95		}
96		if (debug)
97			print_request("", &ptr->request);
98		if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
99		    strcmp(request->r_name, ptr->request.l_name) == 0 &&
100		     ptr->request.type == LEAVE_INVITE)
101			return (&ptr->request);
102	}
103	return ((CTL_MSG *)0);
104}
105
106/*
107 * Look for an identical request, as opposed to a complimentary
108 * one as find_match does
109 */
110CTL_MSG *
111find_request(CTL_MSG *request)
112{
113	TABLE_ENTRY *ptr, *next;
114	time_t current_time;
115
116	clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
117	current_time = ts.tv_sec;
118	/*
119	 * See if this is a repeated message, and check for
120	 * out of date entries in the table while we are it.
121	 */
122	if (debug)
123		print_request("find_request", request);
124	for (ptr = table; ptr != NIL; ptr = next) {
125		next = ptr->next;
126		if ((ptr->time - current_time) > MAX_LIFE) {
127			/* the entry is too old */
128			if (debug)
129				print_request("deleting expired entry",
130				    &ptr->request);
131			delete(ptr);
132			continue;
133		}
134		if (debug)
135			print_request("", &ptr->request);
136		if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
137		    strcmp(request->l_name, ptr->request.l_name) == 0 &&
138		    request->type == ptr->request.type &&
139		    request->pid == ptr->request.pid) {
140			/* update the time if we 'touch' it */
141			ptr->time = current_time;
142			return (&ptr->request);
143		}
144	}
145	return ((CTL_MSG *)0);
146}
147
148void
149insert_table(CTL_MSG *request, CTL_RESPONSE *response)
150{
151	TABLE_ENTRY *ptr;
152	time_t current_time;
153
154	clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
155	current_time = ts.tv_sec;
156	request->id_num = new_id();
157	response->id_num = htonl(request->id_num);
158	/* insert a new entry into the top of the list */
159	ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
160	if (ptr == NIL) {
161		syslog(LOG_ERR, "insert_table: Out of memory");
162		_exit(1);
163	}
164	ptr->time = current_time;
165	ptr->request = *request;
166	ptr->next = table;
167	if (ptr->next != NIL)
168		ptr->next->last = ptr;
169	ptr->last = NIL;
170	table = ptr;
171}
172
173/*
174 * Generate a unique non-zero sequence number
175 */
176int
177new_id(void)
178{
179	static int current_id = 0;
180
181	current_id = (current_id + 1) % MAX_ID;
182	/* 0 is reserved, helps to pick up bugs */
183	if (current_id == 0)
184		current_id = 1;
185	return (current_id);
186}
187
188/*
189 * Delete the invitation with id 'id_num'
190 */
191int
192delete_invite(u_int32_t id_num)
193{
194	TABLE_ENTRY *ptr;
195
196	if (debug)
197		syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
198	for (ptr = table; ptr != NIL; ptr = ptr->next) {
199		if (ptr->request.id_num == id_num)
200			break;
201		if (debug)
202			print_request("", &ptr->request);
203	}
204	if (ptr != NIL) {
205		delete(ptr);
206		return (SUCCESS);
207	}
208	return (NOT_HERE);
209}
210
211/*
212 * Classic delete from a double-linked list
213 */
214static void
215delete(TABLE_ENTRY *ptr)
216{
217
218	if (debug)
219		print_request("delete", &ptr->request);
220	if (table == ptr)
221		table = ptr->next;
222	else if (ptr->last != NIL)
223		ptr->last->next = ptr->next;
224	if (ptr->next != NIL)
225		ptr->next->last = ptr->last;
226	free((char *)ptr);
227}
228