fingerd.c revision 1.36 
1/*	$OpenBSD: fingerd.c,v 1.36 2012/12/04 02:24:47 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/socket.h>
33#include <netinet/in.h>
34#include <arpa/inet.h>
35#include <errno.h>
36
37#include <err.h>
38#include <unistd.h>
39#include <syslog.h>
40#include <netdb.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <string.h>
44#include <stdarg.h>
45#include "pathnames.h"
46
47__dead void logerr(const char *, ...);
48__dead void usage(void);
49
50void
51usage(void)
52{
53	syslog(LOG_ERR,
54	    "usage: fingerd [-lMmpSsu] [-P filename]");
55	exit(2);
56}
57
58
59int
60main(int argc, char *argv[])
61{
62	FILE *fp;
63	int ch, ac = 2;
64	int p[2], logging, secure, user_required, short_list;
65#define	ENTRIES	50
66	char **comp, *prog;
67	char **ap, *av[ENTRIES + 1], line[8192], *lp, *hname;
68	char hostbuf[MAXHOSTNAMELEN];
69
70	prog = _PATH_FINGER;
71	logging = secure = user_required = short_list = 0;
72	openlog("fingerd", LOG_PID, LOG_DAEMON);
73	opterr = 0;
74	while ((ch = getopt(argc, argv, "sluSmMpP:")) != -1)
75		switch (ch) {
76		case 'l':
77			logging = 1;
78			break;
79		case 'P':
80			prog = optarg;
81			break;
82		case 's':
83			secure = 1;
84			break;
85		case 'u':
86			user_required = 1;
87			break;
88		case 'S':
89			if (ac < ENTRIES) {
90				short_list = 1;
91				av[ac++] = "-s";
92			}
93			break;
94		case 'm':
95			if (ac < ENTRIES)
96				av[ac++] = "-m";
97			break;
98		case 'M':
99			if (ac < ENTRIES)
100				av[ac++] = "-M";
101			break;
102		case 'p':
103			if (ac < ENTRIES)
104				av[ac++] = "-p";
105			break;
106		default:
107			usage();
108		}
109
110	if (logging) {
111		struct sockaddr_storage ss;
112		struct sockaddr *sa;
113		socklen_t sval;
114
115		sval = sizeof(ss);
116		if (getpeername(0, (struct sockaddr *)&ss, &sval) < 0)
117			err(1, "getpeername");
118		sa = (struct sockaddr *)&ss;
119		if (getnameinfo(sa, sa->sa_len, hostbuf, sizeof(hostbuf),
120		    NULL, 0, 0) != 0) {
121			strlcpy(hostbuf, "?", sizeof(hostbuf));
122		}
123		hname = hostbuf;
124	}
125
126	if (fgets(line, sizeof(line), stdin) == NULL) {
127		if (logging)
128			syslog(LOG_NOTICE, "query from %s: %s", hname,
129			    feof(stdin) ? "EOF" : strerror(errno));
130		exit(1);
131	}
132
133	if (logging)
134		syslog(LOG_NOTICE, "query from %s: `%.*s'", hname,
135		    (int)strcspn(line, "\r\n"), line);
136
137	/*
138	 * Note: we assume that finger(1) will treat "--" as end of
139	 * command args (ie: that it uses getopt(3)).
140	 */
141	av[ac++] = "--";
142	comp = &av[1];
143	for (lp = line, ap = &av[ac]; ac < ENTRIES;) {
144		size_t len;
145
146		if ((*ap = strtok(lp, " \t\r\n")) == NULL)
147			break;
148		lp = NULL;
149		if (secure && strchr(*ap, '@')) {
150			(void) puts("forwarding service denied\r");
151			exit(1);
152		}
153
154		len = strlen(*ap);
155		while (len > 0 && (*ap)[len - 1] == '@')
156			(*ap)[--len] = '\0';
157		if (**ap == '\0')
158			continue;
159
160		/* RFC1196: "/[Ww]" == "-l" */
161		if ((*ap)[0] == '/' && ((*ap)[1] == 'W' || (*ap)[1] == 'w')) {
162			if (!short_list) {
163				av[1] = "-l";
164				comp = &av[0];
165			}
166		} else {
167			ap++;
168			ac++;
169		}
170	}
171	av[ENTRIES - 1] = NULL;
172
173	if ((lp = strrchr(prog, '/')))
174		*comp = ++lp;
175	else
176		*comp = prog;
177
178	if (user_required) {
179		for (ap = comp + 1; strcmp("--", *(ap++)); )
180			;
181		if (*ap == NULL) {
182			(void) puts("must provide username\r");
183			exit(1);
184		}
185	}
186
187	if (pipe(p) < 0)
188		logerr("pipe: %s", strerror(errno));
189
190	switch (vfork()) {
191	case 0:
192		(void) close(p[0]);
193		if (p[1] != 1) {
194			(void) dup2(p[1], 1);
195			(void) close(p[1]);
196		}
197		execv(prog, comp);
198		logerr("execv: %s: %s", prog, strerror(errno));
199	case -1:
200		logerr("fork: %s", strerror(errno));
201	}
202	(void) close(p[1]);
203	if (!(fp = fdopen(p[0], "r")))
204		logerr("fdopen: %s", strerror(errno));
205	while ((ch = getc(fp)) != EOF) {
206		if (ch == '\n')
207			putchar('\r');
208		putchar(ch);
209	}
210	exit(0);
211}
212
213void
214logerr(const char *fmt, ...)
215{
216	va_list ap;
217
218	va_start(ap, fmt);
219	(void) vsyslog(LOG_ERR, fmt, ap);
220	va_end(ap);
221	exit(1);
222}
223