xref: /freebsd/libexec/talkd/process.c (revision 8d20be1e22095c27faf8fe8b2f0d089739cc742e)
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. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifndef lint
35 #if 0
36 static char sccsid[] = "@(#)process.c	8.2 (Berkeley) 11/16/93";
37 #endif
38 static const char rcsid[] =
39   "$FreeBSD$";
40 #endif /* not lint */
41 
42 /*
43  * process.c handles the requests, which can be of three types:
44  *	ANNOUNCE - announce to a user that a talk is wanted
45  *	LEAVE_INVITE - insert the request into the table
46  *	LOOK_UP - look up to see if a request is waiting in
47  *		  in the table for the local user
48  *	DELETE - delete invitation
49  */
50 #include <sys/param.h>
51 #include <sys/stat.h>
52 #include <sys/socket.h>
53 #include <netinet/in.h>
54 #include <protocols/talkd.h>
55 #include <ctype.h>
56 #include <err.h>
57 #include <netdb.h>
58 #include <paths.h>
59 #include <stdio.h>
60 #include <string.h>
61 #include <syslog.h>
62 #include <utmpx.h>
63 
64 #include "extern.h"
65 
66 void
67 process_request(CTL_MSG *mp, CTL_RESPONSE *rp)
68 {
69 	CTL_MSG *ptr;
70 	char *s;
71 
72 	rp->vers = TALK_VERSION;
73 	rp->type = mp->type;
74 	rp->id_num = htonl(0);
75 	if (mp->vers != TALK_VERSION) {
76 		syslog(LOG_WARNING, "bad protocol version %d", mp->vers);
77 		rp->answer = BADVERSION;
78 		return;
79 	}
80 	mp->id_num = ntohl(mp->id_num);
81 	mp->addr.sa_family = ntohs(mp->addr.sa_family);
82 	if (mp->addr.sa_family != AF_INET) {
83 		syslog(LOG_WARNING, "bad address, family %d",
84 		    mp->addr.sa_family);
85 		rp->answer = BADADDR;
86 		return;
87 	}
88 	mp->ctl_addr.sa_family = ntohs(mp->ctl_addr.sa_family);
89 	if (mp->ctl_addr.sa_family != AF_INET) {
90 		syslog(LOG_WARNING, "bad control address, family %d",
91 		    mp->ctl_addr.sa_family);
92 		rp->answer = BADCTLADDR;
93 		return;
94 	}
95 	for (s = mp->l_name; *s; s++)
96 		if (!isprint(*s)) {
97 			syslog(LOG_NOTICE, "illegal user name. Aborting");
98 			rp->answer = FAILED;
99 			return;
100 		}
101 	mp->pid = ntohl(mp->pid);
102 	if (debug)
103 		print_request("process_request", mp);
104 	switch (mp->type) {
105 
106 	case ANNOUNCE:
107 		do_announce(mp, rp);
108 		break;
109 
110 	case LEAVE_INVITE:
111 		ptr = find_request(mp);
112 		if (ptr != (CTL_MSG *)0) {
113 			rp->id_num = htonl(ptr->id_num);
114 			rp->answer = SUCCESS;
115 		} else
116 			insert_table(mp, rp);
117 		break;
118 
119 	case LOOK_UP:
120 		ptr = find_match(mp);
121 		if (ptr != (CTL_MSG *)0) {
122 			rp->id_num = htonl(ptr->id_num);
123 			rp->addr = ptr->addr;
124 			rp->addr.sa_family = htons(ptr->addr.sa_family);
125 			rp->answer = SUCCESS;
126 		} else
127 			rp->answer = NOT_HERE;
128 		break;
129 
130 	case DELETE:
131 		rp->answer = delete_invite(mp->id_num);
132 		break;
133 
134 	default:
135 		rp->answer = UNKNOWN_REQUEST;
136 		break;
137 	}
138 	if (debug)
139 		print_response("process_request", rp);
140 }
141 
142 void
143 do_announce(CTL_MSG *mp, CTL_RESPONSE *rp)
144 {
145 	struct hostent *hp;
146 	CTL_MSG *ptr;
147 	int result;
148 
149 	/* see if the user is logged */
150 	result = find_user(mp->r_name, mp->r_tty);
151 	if (result != SUCCESS) {
152 		rp->answer = result;
153 		return;
154 	}
155 #define	satosin(sa)	((struct sockaddr_in *)(void *)(sa))
156 	hp = gethostbyaddr(&satosin(&mp->ctl_addr)->sin_addr,
157 		sizeof (struct in_addr), AF_INET);
158 	if (hp == (struct hostent *)0) {
159 		rp->answer = MACHINE_UNKNOWN;
160 		return;
161 	}
162 	ptr = find_request(mp);
163 	if (ptr == (CTL_MSG *) 0) {
164 		insert_table(mp, rp);
165 		rp->answer = announce(mp, hp->h_name);
166 		return;
167 	}
168 	if (mp->id_num > ptr->id_num) {
169 		/*
170 		 * This is an explicit re-announce, so update the id_num
171 		 * field to avoid duplicates and re-announce the talk.
172 		 */
173 		ptr->id_num = new_id();
174 		rp->id_num = htonl(ptr->id_num);
175 		rp->answer = announce(mp, hp->h_name);
176 	} else {
177 		/* a duplicated request, so ignore it */
178 		rp->id_num = htonl(ptr->id_num);
179 		rp->answer = SUCCESS;
180 	}
181 }
182 
183 /*
184  * Search utmp for the local user
185  */
186 int
187 find_user(const char *name, char *tty)
188 {
189 	struct utmpx *ut;
190 	int status;
191 	struct stat statb;
192 	time_t best = 0;
193 	char ftty[sizeof(_PATH_DEV) - 1 + sizeof(ut->ut_line)];
194 
195 	setutxent();
196 	status = NOT_HERE;
197 	(void) strcpy(ftty, _PATH_DEV);
198 	while ((ut = getutxent()) != NULL)
199 		if (ut->ut_type == USER_PROCESS &&
200 		    strcmp(ut->ut_user, name) == 0) {
201 			if (*tty == '\0' || best != 0) {
202 				if (best == 0)
203 					status = PERMISSION_DENIED;
204 				/* no particular tty was requested */
205 				(void) strcpy(ftty + sizeof(_PATH_DEV) - 1,
206 				    ut->ut_line);
207 				if (stat(ftty, &statb) == 0) {
208 					if (!(statb.st_mode & 020))
209 						continue;
210 					if (statb.st_atime > best) {
211 						best = statb.st_atime;
212 						(void) strcpy(tty, ut->ut_line);
213 						status = SUCCESS;
214 						continue;
215 					}
216 				}
217 			}
218 			if (strcmp(ut->ut_line, tty) == 0) {
219 				status = SUCCESS;
220 				break;
221 			}
222 		}
223 	endutxent();
224 	return (status);
225 }
226