xref: /freebsd/libexec/fingerd/fingerd.c (revision f0a75d274af375d15b97b830966b99a02b7db911)
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 static const char copyright[] =
36 "@(#) Copyright (c) 1983, 1993\n\
37 	The Regents of the University of California.  All rights reserved.\n";
38 #endif /* not lint */
39 
40 #ifndef lint
41 #if 0
42 static char sccsid[] = "@(#)fingerd.c	8.1 (Berkeley) 6/4/93";
43 #endif
44 static const char rcsid[] =
45   "$FreeBSD$";
46 #endif /* not lint */
47 
48 #include <sys/types.h>
49 #include <sys/param.h>
50 #include <sys/socket.h>
51 #include <netinet/in.h>
52 #include <netinet/tcp.h>
53 #include <arpa/inet.h>
54 #include <errno.h>
55 
56 #include <unistd.h>
57 #include <syslog.h>
58 #include <libutil.h>
59 #include <netdb.h>
60 #include <stdio.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include "pathnames.h"
64 
65 void logerr(const char *, ...) __printflike(1, 2);
66 
67 int
68 main(int argc, char *argv[])
69 {
70 	FILE *fp;
71 	int ch;
72 	char *lp;
73 	struct sockaddr_storage ss;
74 	socklen_t sval;
75 	int p[2], logging, pflag, secure;
76 #define	ENTRIES	50
77 	char **ap, *av[ENTRIES + 1], **comp, line[1024], *prog;
78 	char rhost[MAXHOSTNAMELEN];
79 
80 	prog = _PATH_FINGER;
81 	logging = pflag = secure = 0;
82 	openlog("fingerd", LOG_PID | LOG_CONS, LOG_DAEMON);
83 	opterr = 0;
84 	while ((ch = getopt(argc, argv, "lp:s")) != -1)
85 		switch (ch) {
86 		case 'l':
87 			logging = 1;
88 			break;
89 		case 'p':
90 			prog = optarg;
91 			pflag = 1;
92 			break;
93 		case 's':
94 			secure = 1;
95 			break;
96 		case '?':
97 		default:
98 			logerr("illegal option -- %c", optopt);
99 		}
100 
101 	/*
102 	 * Enable server-side Transaction TCP.
103 	 */
104 	{
105 		int one = 1;
106 		if (setsockopt(STDOUT_FILENO, IPPROTO_TCP, TCP_NOPUSH, &one,
107 			       sizeof one) < 0) {
108 			logerr("setsockopt(TCP_NOPUSH) failed: %m");
109 		}
110 	}
111 
112 	if (!fgets(line, sizeof(line), stdin))
113 		exit(1);
114 
115 	if (logging || pflag) {
116 		sval = sizeof(ss);
117 		if (getpeername(0, (struct sockaddr *)&ss, &sval) < 0)
118 			logerr("getpeername: %s", strerror(errno));
119 		realhostname_sa(rhost, sizeof rhost - 1,
120 				(struct sockaddr *)&ss, sval);
121 		rhost[sizeof(rhost) - 1] = '\0';
122 		if (pflag)
123 			setenv("FINGERD_REMOTE_HOST", rhost, 1);
124 	}
125 
126 	if (logging) {
127 		char *t;
128 		char *end;
129 
130 		end = memchr(line, 0, sizeof(line));
131 		if (end == NULL) {
132 			if ((t = malloc(sizeof(line) + 1)) == NULL)
133 				logerr("malloc: %s", strerror(errno));
134 			memcpy(t, line, sizeof(line));
135 			t[sizeof(line)] = 0;
136 		} else {
137 			if ((t = strdup(line)) == NULL)
138 				logerr("strdup: %s", strerror(errno));
139 		}
140 		for (end = t; *end; end++)
141 			if (*end == '\n' || *end == '\r')
142 				*end = ' ';
143 		syslog(LOG_NOTICE, "query from %s: `%s'", rhost, t);
144 	}
145 
146 	comp = &av[1];
147 	av[2] = "--";
148 	for (lp = line, ap = &av[3];;) {
149 		*ap = strtok(lp, " \t\r\n");
150 		if (!*ap) {
151 			if (secure && ap == &av[3]) {
152 				puts("must provide username\r\n");
153 				exit(1);
154 			}
155 			break;
156 		}
157 		if (secure && strchr(*ap, '@')) {
158 			puts("forwarding service denied\r\n");
159 			exit(1);
160 		}
161 
162 		/* RFC742: "/[Ww]" == "-l" */
163 		if ((*ap)[0] == '/' && ((*ap)[1] == 'W' || (*ap)[1] == 'w')) {
164 			av[1] = "-l";
165 			comp = &av[0];
166 		}
167 		else if (++ap == av + ENTRIES) {
168 			*ap = NULL;
169 			break;
170 		}
171 		lp = NULL;
172 	}
173 
174 	if ((lp = strrchr(prog, '/')) != NULL)
175 		*comp = ++lp;
176 	else
177 		*comp = prog;
178 	if (pipe(p) < 0)
179 		logerr("pipe: %s", strerror(errno));
180 
181 	switch(vfork()) {
182 	case 0:
183 		(void)close(p[0]);
184 		if (p[1] != STDOUT_FILENO) {
185 			(void)dup2(p[1], STDOUT_FILENO);
186 			(void)close(p[1]);
187 		}
188 		dup2(STDOUT_FILENO, STDERR_FILENO);
189 
190 		execv(prog, comp);
191 		write(STDERR_FILENO, prog, strlen(prog));
192 #define MSG ": cannot execute\n"
193 		write(STDERR_FILENO, MSG, strlen(MSG));
194 #undef MSG
195 		_exit(1);
196 	case -1:
197 		logerr("fork: %s", strerror(errno));
198 	}
199 	(void)close(p[1]);
200 	if (!(fp = fdopen(p[0], "r")))
201 		logerr("fdopen: %s", strerror(errno));
202 	while ((ch = getc(fp)) != EOF) {
203 		if (ch == '\n')
204 			putchar('\r');
205 		putchar(ch);
206 	}
207 	exit(0);
208 }
209 
210 #include <stdarg.h>
211 
212 void
213 logerr(const char *fmt, ...)
214 {
215 	va_list ap;
216 	va_start(ap, fmt);
217 	(void)vsyslog(LOG_ERR, fmt, ap);
218 	va_end(ap);
219 	exit(1);
220 	/* NOTREACHED */
221 }
222