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 * @(#)table.c 8.1 (Berkeley) 6/4/93
30 * $FreeBSD: src/libexec/talkd/table.c,v 1.7 1999/08/28 00:10:17 peter Exp $
31 */
32
33 /*
34 * Routines to handle insertion, deletion, etc on the table
35 * of requests kept by the daemon. Nothing fancy here, linear
36 * search on a double-linked list. A time is kept with each
37 * entry so that overly old invitations can be eliminated.
38 *
39 * Consider this a mis-guided attempt at modularity
40 */
41 #include <sys/param.h>
42 #include <sys/time.h>
43 #include <sys/socket.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 extern int debug;
56 struct timeval tp;
57
58 typedef struct table_entry TABLE_ENTRY;
59
60 struct table_entry {
61 CTL_MSG request;
62 long time;
63 TABLE_ENTRY *next;
64 TABLE_ENTRY *last;
65 };
66
67 static void delete(TABLE_ENTRY *);
68
69 TABLE_ENTRY *table = NULL;
70
71 /*
72 * Look in the table for an invitation that matches the current
73 * request looking for an invitation
74 */
75 CTL_MSG *
find_match(CTL_MSG * request)76 find_match(CTL_MSG *request)
77 {
78 TABLE_ENTRY *ptr;
79 time_t current_time;
80
81 gettimeofday(&tp, NULL);
82 current_time = tp.tv_sec;
83 if (debug)
84 print_request("find_match", request);
85 for (ptr = table; ptr != NULL; ptr = ptr->next) {
86 if ((ptr->time - current_time) > MAX_LIFE) {
87 /* the entry is too old */
88 if (debug)
89 print_request("deleting expired entry",
90 &ptr->request);
91 delete(ptr);
92 continue;
93 }
94 if (debug)
95 print_request("", &ptr->request);
96 if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
97 strcmp(request->r_name, ptr->request.l_name) == 0 &&
98 ptr->request.type == LEAVE_INVITE)
99 return (&ptr->request);
100 }
101 return (NULL);
102 }
103
104 /*
105 * Look for an identical request, as opposed to a complimentary
106 * one as find_match does
107 */
108 CTL_MSG *
find_request(CTL_MSG * request)109 find_request(CTL_MSG *request)
110 {
111 TABLE_ENTRY *ptr;
112 time_t current_time;
113
114 gettimeofday(&tp, NULL);
115 current_time = tp.tv_sec;
116 /*
117 * See if this is a repeated message, and check for
118 * out of date entries in the table while we are it.
119 */
120 if (debug)
121 print_request("find_request", request);
122 for (ptr = table; ptr != NULL; ptr = ptr->next) {
123 if ((ptr->time - current_time) > MAX_LIFE) {
124 /* the entry is too old */
125 if (debug)
126 print_request("deleting expired entry",
127 &ptr->request);
128 delete(ptr);
129 continue;
130 }
131 if (debug)
132 print_request("", &ptr->request);
133 if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
134 strcmp(request->l_name, ptr->request.l_name) == 0 &&
135 request->type == ptr->request.type &&
136 request->pid == ptr->request.pid) {
137 /* update the time if we 'touch' it */
138 ptr->time = current_time;
139 return (&ptr->request);
140 }
141 }
142 return (NULL);
143 }
144
145 void
insert_table(CTL_MSG * request,CTL_RESPONSE * response)146 insert_table(CTL_MSG *request, CTL_RESPONSE *response)
147 {
148 TABLE_ENTRY *ptr;
149 time_t current_time;
150
151 gettimeofday(&tp, NULL);
152 current_time = tp.tv_sec;
153 request->id_num = new_id();
154 response->id_num = htonl(request->id_num);
155 /* insert a new entry into the top of the list */
156 ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
157 if (ptr == NULL) {
158 syslog(LOG_ERR, "insert_table: Out of memory");
159 _exit(1);
160 }
161 ptr->time = current_time;
162 ptr->request = *request;
163 ptr->next = table;
164 if (ptr->next != NULL)
165 ptr->next->last = ptr;
166 ptr->last = NULL;
167 table = ptr;
168 }
169
170 /*
171 * Generate a unique non-zero sequence number
172 */
173 int
new_id(void)174 new_id(void)
175 {
176 static int current_id = 0;
177
178 current_id = (current_id + 1) % MAX_ID;
179 /* 0 is reserved, helps to pick up bugs */
180 if (current_id == 0)
181 current_id = 1;
182 return (current_id);
183 }
184
185 /*
186 * Delete the invitation with id 'id_num'
187 */
188 int
delete_invite(unsigned int id_num)189 delete_invite(unsigned int id_num)
190 {
191 TABLE_ENTRY *ptr;
192
193 ptr = table;
194 if (debug)
195 syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
196 for (ptr = table; ptr != NULL; ptr = ptr->next) {
197 if (ptr->request.id_num == id_num)
198 break;
199 if (debug)
200 print_request("", &ptr->request);
201 }
202 if (ptr != NULL) {
203 delete(ptr);
204 return (SUCCESS);
205 }
206 return (NOT_HERE);
207 }
208
209 /*
210 * Classic delete from a double-linked list
211 */
212 static void
delete(TABLE_ENTRY * ptr)213 delete(TABLE_ENTRY *ptr)
214 {
215
216 if (debug)
217 print_request("delete", &ptr->request);
218 if (table == ptr)
219 table = ptr->next;
220 else if (ptr->last != NULL)
221 ptr->last->next = ptr->next;
222 if (ptr->next != NULL)
223 ptr->next->last = ptr->last;
224 free((char *)ptr);
225 }
226