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
57 static struct timespec ts;
58
59 typedef struct table_entry TABLE_ENTRY;
60
61 struct table_entry {
62 CTL_MSG request;
63 long time;
64 TABLE_ENTRY *next;
65 TABLE_ENTRY *last;
66 };
67
68 static void delete(TABLE_ENTRY *);
69
70 static 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 */
76 CTL_MSG *
find_match(CTL_MSG * request)77 find_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 */
110 CTL_MSG *
find_request(CTL_MSG * request)111 find_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
148 void
insert_table(CTL_MSG * request,CTL_RESPONSE * response)149 insert_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 */
176 int
new_id(void)177 new_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 */
191 int
delete_invite(u_int32_t id_num)192 delete_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 */
214 static void
delete(TABLE_ENTRY * ptr)215 delete(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