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
54 struct timeval tp;
55
56 typedef struct table_entry TABLE_ENTRY;
57
58 struct table_entry {
59 CTL_MSG request;
60 time_t time;
61 TAILQ_ENTRY(table_entry) list;
62 };
63 TAILQ_HEAD(, table_entry) table;
64
65 static void delete(TABLE_ENTRY *);
66
67 /*
68 * Init the table
69 */
70 void
init_table(void)71 init_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 */
80 CTL_MSG *
find_match(CTL_MSG * request)81 find_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 */
117 CTL_MSG *
find_request(CTL_MSG * request)118 find_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
155 void
insert_table(CTL_MSG * request,CTL_RESPONSE * response)156 insert_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 */
181 int
new_id(void)182 new_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 */
196 int
delete_invite(int id_num)197 delete_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 */
219 static void
delete(TABLE_ENTRY * ptr)220 delete(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