fingerd.c revision 1.35 
1/*	$OpenBSD: fingerd.c,v 1.35 2009/10/27 23:59:31 deraadt Exp $	*/
2
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#include <sys/param.h>
33#include <sys/socket.h>
34#include <netinet/in.h>
35#include <arpa/inet.h>
36#include <errno.h>
37
38#include <err.h>
39#include <unistd.h>
40#include <syslog.h>
41#include <netdb.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include <stdarg.h>
46#include "pathnames.h"
47
48__dead void logerr(const char *, ...);
49__dead void usage(void);
50
51void
52usage(void)
53{
54	syslog(LOG_ERR,
55	    "usage: fingerd [-lMmpSsu] [-P filename]");
56	exit(2);
57}
58
59
60int
61main(int argc, char *argv[])
62{
63	FILE *fp;
64	int ch, ac = 2;
65	int p[2], logging, secure, user_required, short_list;
66#define	ENTRIES	50
67	char **comp, *prog;
68	char **ap, *av[ENTRIES + 1], line[8192], *lp, *hname;
69	char hostbuf[MAXHOSTNAMELEN];
70
71	prog = _PATH_FINGER;
72	logging = secure = user_required = short_list = 0;
73	openlog("fingerd", LOG_PID, LOG_DAEMON);
74	opterr = 0;
75	while ((ch = getopt(argc, argv, "sluSmMpP:")) != -1)
76		switch (ch) {
77		case 'l':
78			logging = 1;
79			break;
80		case 'P':
81			prog = optarg;
82			break;
83		case 's':
84			secure = 1;
85			break;
86		case 'u':
87			user_required = 1;
88			break;
89		case 'S':
90			if (ac < ENTRIES) {
91				short_list = 1;
92				av[ac++] = "-s";
93			}
94			break;
95		case 'm':
96			if (ac < ENTRIES)
97				av[ac++] = "-m";
98			break;
99		case 'M':
100			if (ac < ENTRIES)
101				av[ac++] = "-M";
102			break;
103		case 'p':
104			if (ac < ENTRIES)
105				av[ac++] = "-p";
106			break;
107		default:
108			usage();
109		}
110
111	if (logging) {
112		struct sockaddr_storage ss;
113		struct sockaddr *sa;
114		socklen_t sval;
115
116		sval = sizeof(ss);
117		if (getpeername(0, (struct sockaddr *)&ss, &sval) < 0)
118			err(1, "getpeername");
119		sa = (struct sockaddr *)&ss;
120		if (getnameinfo(sa, sa->sa_len, hostbuf, sizeof(hostbuf),
121		    NULL, 0, 0) != 0) {
122			strlcpy(hostbuf, "?", sizeof(hostbuf));
123		}
124		hname = hostbuf;
125	}
126
127	if (fgets(line, sizeof(line), stdin) == NULL) {
128		if (logging)
129			syslog(LOG_NOTICE, "query from %s: %s", hname,
130			    feof(stdin) ? "EOF" : strerror(errno));
131		exit(1);
132	}
133
134	if (logging)
135		syslog(LOG_NOTICE, "query from %s: `%.*s'", hname,
136		    (int)strcspn(line, "\r\n"), line);
137
138	/*
139	 * Note: we assume that finger(1) will treat "--" as end of
140	 * command args (ie: that it uses getopt(3)).
141	 */
142	av[ac++] = "--";
143	comp = &av[1];
144	for (lp = line, ap = &av[ac]; ac < ENTRIES;) {
145		size_t len;
146
147		if ((*ap = strtok(lp, " \t\r\n")) == NULL)
148			break;
149		lp = NULL;
150		if (secure && strchr(*ap, '@')) {
151			(void) puts("forwarding service denied\r");
152			exit(1);
153		}
154
155		len = strlen(*ap);
156		while (len > 0 && (*ap)[len - 1] == '@')
157			(*ap)[--len] = '\0';
158		if (**ap == '\0')
159			continue;
160
161		/* RFC1196: "/[Ww]" == "-l" */
162		if ((*ap)[0] == '/' && ((*ap)[1] == 'W' || (*ap)[1] == 'w')) {
163			if (!short_list) {
164				av[1] = "-l";
165				comp = &av[0];
166			}
167		} else {
168			ap++;
169			ac++;
170		}
171	}
172	av[ENTRIES - 1] = NULL;
173
174	if ((lp = strrchr(prog, '/')))
175		*comp = ++lp;
176	else
177		*comp = prog;
178
179	if (user_required) {
180		for (ap = comp + 1; strcmp("--", *(ap++)); )
181			;
182		if (*ap == NULL) {
183			(void) puts("must provide username\r");
184			exit(1);
185		}
186	}
187
188	if (pipe(p) < 0)
189		logerr("pipe: %s", strerror(errno));
190
191	switch (vfork()) {
192	case 0:
193		(void) close(p[0]);
194		if (p[1] != 1) {
195			(void) dup2(p[1], 1);
196			(void) close(p[1]);
197		}
198		execv(prog, comp);
199		logerr("execv: %s: %s", prog, strerror(errno));
200	case -1:
201		logerr("fork: %s", strerror(errno));
202	}
203	(void) close(p[1]);
204	if (!(fp = fdopen(p[0], "r")))
205		logerr("fdopen: %s", strerror(errno));
206	while ((ch = getc(fp)) != EOF) {
207		if (ch == '\n')
208			putchar('\r');
209		putchar(ch);
210	}
211	exit(0);
212}
213
214void
215logerr(const char *fmt, ...)
216{
217	va_list ap;
218
219	va_start(ap, fmt);
220	(void) vsyslog(LOG_ERR, fmt, ap);
221	va_end(ap);
222	exit(1);
223}
224