builtins.c revision 49054 
1/*-
2 * Copyright (c) 1983, 1991, 1993, 1994
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 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $Id: builtins.c,v 1.9 1999/07/24 13:02:09 sheldonh Exp $
27 *
28 */
29
30#include <sys/filio.h>
31#include <sys/ioccom.h>
32#include <sys/param.h>
33#include <sys/stat.h>
34#include <sys/socket.h>
35#include <sys/sysctl.h>
36#include <sys/ucred.h>
37#include <sys/uio.h>
38#include <sys/utsname.h>
39
40#include <ctype.h>
41#include <err.h>
42#include <errno.h>
43#include <limits.h>
44#include <pwd.h>
45#include <signal.h>
46#include <stdlib.h>
47#include <string.h>
48#include <sysexits.h>
49#include <syslog.h>
50#include <unistd.h>
51
52#include "inetd.h"
53
54extern int	 debug;
55extern struct servtab *servtab;
56
57char ring[128];
58char *endring;
59
60int check_loop __P((struct sockaddr_in *, struct servtab *sep));
61void inetd_setproctitle __P((char *, int));
62
63struct biltin biltins[] = {
64	/* Echo received data */
65	{ "echo",	SOCK_STREAM,	1, -1,	echo_stream },
66	{ "echo",	SOCK_DGRAM,	0, 1,	echo_dg },
67
68	/* Internet /dev/null */
69	{ "discard",	SOCK_STREAM,	1, -1,	discard_stream },
70	{ "discard",	SOCK_DGRAM,	0, 1,	discard_dg },
71
72	/* Return 32 bit time since 1970 */
73	{ "time",	SOCK_STREAM,	0, -1,	machtime_stream },
74	{ "time",	SOCK_DGRAM,	0, 1,	machtime_dg },
75
76	/* Return human-readable time */
77	{ "daytime",	SOCK_STREAM,	0, -1,	daytime_stream },
78	{ "daytime",	SOCK_DGRAM,	0, 1,	daytime_dg },
79
80	/* Familiar character generator */
81	{ "chargen",	SOCK_STREAM,	1, -1,	chargen_stream },
82	{ "chargen",	SOCK_DGRAM,	0, 1,	chargen_dg },
83
84	{ "tcpmux",	SOCK_STREAM,	1, -1,	(void (*)())tcpmux },
85
86	{ "auth",	SOCK_STREAM,	1, -1,	ident_stream },
87
88	{ NULL }
89};
90
91/*
92 * RFC864 Character Generator Protocol. Generates character data without
93 * any regard for input.
94 */
95
96void
97initring()
98{
99	int i;
100
101	endring = ring;
102
103	for (i = 0; i <= 128; ++i)
104		if (isprint(i))
105			*endring++ = i;
106}
107
108/* ARGSUSED */
109void
110chargen_dg(s, sep)		/* Character generator */
111	int s;
112	struct servtab *sep;
113{
114	struct sockaddr_in sin;
115	static char *rs;
116	int len, size;
117	char text[LINESIZ+2];
118
119	if (endring == 0) {
120		initring();
121		rs = ring;
122	}
123
124	size = sizeof(sin);
125	if (recvfrom(s, text, sizeof(text), 0,
126		     (struct sockaddr *)&sin, &size) < 0)
127		return;
128
129	if (check_loop(&sin, sep))
130		return;
131
132	if ((len = endring - rs) >= LINESIZ)
133		memmove(text, rs, LINESIZ);
134	else {
135		memmove(text, rs, len);
136		memmove(text + len, ring, LINESIZ - len);
137	}
138	if (++rs == endring)
139		rs = ring;
140	text[LINESIZ] = '\r';
141	text[LINESIZ + 1] = '\n';
142	(void) sendto(s, text, sizeof(text), 0,
143		      (struct sockaddr *)&sin, sizeof(sin));
144}
145
146/* ARGSUSED */
147void
148chargen_stream(s, sep)		/* Character generator */
149	int s;
150	struct servtab *sep;
151{
152	int len;
153	char *rs, text[LINESIZ+2];
154
155	inetd_setproctitle(sep->se_service, s);
156
157	if (!endring) {
158		initring();
159		rs = ring;
160	}
161
162	text[LINESIZ] = '\r';
163	text[LINESIZ + 1] = '\n';
164	for (rs = ring;;) {
165		if ((len = endring - rs) >= LINESIZ)
166			memmove(text, rs, LINESIZ);
167		else {
168			memmove(text, rs, len);
169			memmove(text + len, ring, LINESIZ - len);
170		}
171		if (++rs == endring)
172			rs = ring;
173		if (write(s, text, sizeof(text)) != sizeof(text))
174			break;
175	}
176	exit(0);
177}
178
179/*
180 * RFC867 Daytime Protocol. Sends the current date and time as an ascii
181 * character string without any regard for input.
182 */
183
184/* ARGSUSED */
185void
186daytime_dg(s, sep)		/* Return human-readable time of day */
187	int s;
188	struct servtab *sep;
189{
190	char buffer[256];
191	time_t clock;
192	struct sockaddr_in sin;
193	int size;
194
195	clock = time((time_t *) 0);
196
197	size = sizeof(sin);
198	if (recvfrom(s, buffer, sizeof(buffer), 0,
199		     (struct sockaddr *)&sin, &size) < 0)
200		return;
201
202	if (check_loop(&sin, sep))
203		return;
204
205	(void) sprintf(buffer, "%.24s\r\n", ctime(&clock));
206	(void) sendto(s, buffer, strlen(buffer), 0,
207		      (struct sockaddr *)&sin, sizeof(sin));
208}
209
210/* ARGSUSED */
211void
212daytime_stream(s, sep)		/* Return human-readable time of day */
213	int s;
214	struct servtab *sep;
215{
216	char buffer[256];
217	time_t clock;
218
219	clock = time((time_t *) 0);
220
221	(void) sprintf(buffer, "%.24s\r\n", ctime(&clock));
222	(void) write(s, buffer, strlen(buffer));
223}
224
225/*
226 * RFC863 Discard Protocol. Any data received is thrown away and no response
227 * is sent.
228 */
229
230/* ARGSUSED */
231void
232discard_dg(s, sep)		/* Discard service -- ignore data */
233	int s;
234	struct servtab *sep;
235{
236	char buffer[BUFSIZE];
237
238	(void) read(s, buffer, sizeof(buffer));
239}
240
241/* ARGSUSED */
242void
243discard_stream(s, sep)		/* Discard service -- ignore data */
244	int s;
245	struct servtab *sep;
246{
247	int ret;
248	char buffer[BUFSIZE];
249
250	inetd_setproctitle(sep->se_service, s);
251	while (1) {
252		while ((ret = read(s, buffer, sizeof(buffer))) > 0)
253			;
254		if (ret == 0 || errno != EINTR)
255			break;
256	}
257	exit(0);
258}
259
260/*
261 * RFC862 Echo Protocol. Any data received is sent back to the sender as
262 * received.
263 */
264
265/* ARGSUSED */
266void
267echo_dg(s, sep)			/* Echo service -- echo data back */
268	int s;
269	struct servtab *sep;
270{
271	char buffer[BUFSIZE];
272	int i, size;
273	struct sockaddr_in sin;
274
275	size = sizeof(sin);
276	if ((i = recvfrom(s, buffer, sizeof(buffer), 0,
277			  (struct sockaddr *)&sin, &size)) < 0)
278		return;
279
280	if (check_loop(&sin, sep))
281		return;
282
283	(void) sendto(s, buffer, i, 0, (struct sockaddr *)&sin,
284		      sizeof(sin));
285}
286
287/* ARGSUSED */
288void
289echo_stream(s, sep)		/* Echo service -- echo data back */
290	int s;
291	struct servtab *sep;
292{
293	char buffer[BUFSIZE];
294	int i;
295
296	inetd_setproctitle(sep->se_service, s);
297	while ((i = read(s, buffer, sizeof(buffer))) > 0 &&
298	    write(s, buffer, i) > 0)
299		;
300	exit(0);
301}
302
303/*
304 * RFC1413 Identification Protocol. Given a TCP port number pair, return a
305 * character string which identifies the owner of that connection on the
306 * server's system. Extended to allow for ~/.fakeid support.
307 */
308
309/* ARGSUSED */
310void
311iderror(lport, fport, s, er)
312	int lport, fport, s, er;
313{
314	char *p;
315
316	asprintf(&p, "%d , %d : ERROR : %s\r\n", lport, fport,
317	    er == -1 ? "HIDDEN-USER" : er ? strerror(er) : "UNKNOWN-ERROR");
318	if (p == NULL) {
319		syslog(LOG_ERR, "Out of memory.");
320		exit(EX_OSERR);
321	}
322	write(s, p, strlen(p));
323	free(p);
324
325	exit(0);
326}
327
328/* ARGSUSED */
329void
330ident_stream(s, sep)		/* Ident service */
331	int s;
332	struct servtab *sep;
333{
334	struct sockaddr_in sin[2];
335	struct ucred uc;
336	struct timeval tv = {
337		10,
338		0
339	};
340	struct passwd *pw;
341	fd_set fdset;
342	char buf[BUFSIZE], *cp = NULL, *p, **av, *osname = NULL;
343	int len, c, rflag = 0, fflag = 0, argc = 0;
344	u_short lport, fport;
345
346	inetd_setproctitle(sep->se_service, s);
347	optind = 1;
348	optreset = 1;
349	for (av = sep->se_argv; *av; av++)
350		argc++;
351	if (argc) {
352		int sec, usec;
353
354		while ((c = getopt(argc, sep->se_argv, "fro:t:")) != -1)
355			switch (c) {
356			case 'f':
357				fflag = 1;
358				break;
359			case 'r':
360				rflag = 1;
361				break;
362			case 'o':
363				osname = optarg;
364				break;
365			case 't':
366				switch (sscanf(optarg, "%d.%d", &sec, &usec)) {
367				case 2:
368					tv.tv_usec = usec;
369				case 1:
370					tv.tv_sec = sec;
371					break;
372				default:
373					if (debug)
374						warnx("bad -t argument");
375					break;
376				}
377				break;
378			default:
379				break;
380			}
381	}
382	if (osname == NULL) {
383		struct utsname un;
384
385		if (uname(&un) == -1)
386			iderror(0, 0, s, errno);
387		osname = un.sysname;
388	}
389	len = sizeof(sin[0]);
390	if (getsockname(s, (struct sockaddr *)&sin[0], &len) == -1)
391		iderror(0, 0, s, errno);
392	len = sizeof(sin[1]);
393	if (getpeername(s, (struct sockaddr *)&sin[1], &len) == -1)
394		iderror(0, 0, s, errno);
395	FD_ZERO(&fdset);
396	FD_SET(s, &fdset);
397	if (select(s + 1, &fdset, NULL, NULL, &tv) == -1)
398		iderror(0, 0, s, errno);
399	if (ioctl(s, FIONREAD, &len) == -1)
400		iderror(0, 0, s, errno);
401	if (len >= sizeof(buf))
402		len = sizeof(buf) - 1;
403	len = read(s, buf, len);
404	if (len == -1)
405		iderror(0, 0, s, errno);
406	buf[len] = '\0';
407	if (sscanf(buf, "%hu , %hu", &lport, &fport) != 2)
408		iderror(0, 0, s, 0);
409	if (!rflag)
410		iderror(lport, fport, s, -1);
411	sin[0].sin_port = htons(lport);
412	sin[1].sin_port = htons(fport);
413	len = sizeof(uc);
414	if (sysctlbyname("net.inet.tcp.getcred", &uc, &len, sin,
415	    sizeof(sin)) == -1)
416		iderror(lport, fport, s, errno);
417	pw = getpwuid(uc.cr_uid);
418	if (pw == NULL)
419		iderror(lport, fport, s, errno);
420	if (fflag) {
421		FILE *fakeid = NULL;
422		char fakeid_path[PATH_MAX];
423		struct stat sb;
424
425		seteuid(pw->pw_uid);
426		setegid(pw->pw_gid);
427		snprintf(fakeid_path, sizeof(fakeid_path), "%s/.fakeid",
428		    pw->pw_dir);
429		if ((fakeid = fopen(fakeid_path, "r")) != NULL &&
430		    fstat(fileno(fakeid), &sb) != -1 && S_ISREG(sb.st_mode)) {
431			buf[sizeof(buf) - 1] = '\0';
432			if (fgets(buf, sizeof(buf), fakeid) == NULL) {
433				cp = pw->pw_name;
434				fclose(fakeid);
435				goto printit;
436			}
437			fclose(fakeid);
438			strtok(buf, "\r\n");
439			if (strlen(buf) > 16)
440				buf[16] = '\0';
441			cp = buf;
442			while (isspace(*cp))
443				cp++;
444			strtok(cp, " \t");
445			if (!*cp || getpwnam(cp))
446				cp = getpwuid(uc.cr_uid)->pw_name;
447		} else
448			cp = pw->pw_name;
449	} else
450		cp = pw->pw_name;
451printit:
452	if (asprintf(&p, "%d , %d : USERID : %s : %s\r\n", lport, fport, osname,
453	    cp) == -1) {
454		syslog(LOG_ERR, "Out of memory.");
455		exit(EX_OSERR);
456	}
457	write(s, p, strlen(p));
458	free(p);
459
460	exit(0);
461}
462
463/*
464 * RFC738 Time Server.
465 * Return a machine readable date and time, in the form of the
466 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
467 * returns the number of seconds since midnight, Jan 1, 1970,
468 * we must add 2208988800 seconds to this figure to make up for
469 * some seventy years Bell Labs was asleep.
470 */
471
472unsigned long
473machtime()
474{
475	struct timeval tv;
476
477	if (gettimeofday(&tv, (struct timezone *)NULL) < 0) {
478		if (debug)
479			warnx("unable to get time of day");
480		return (0L);
481	}
482#define	OFFSET ((u_long)25567 * 24*60*60)
483	return (htonl((long)(tv.tv_sec + OFFSET)));
484#undef OFFSET
485}
486
487/* ARGSUSED */
488void
489machtime_dg(s, sep)
490	int s;
491	struct servtab *sep;
492{
493	unsigned long result;
494	struct sockaddr_in sin;
495	int size;
496
497	size = sizeof(sin);
498	if (recvfrom(s, (char *)&result, sizeof(result), 0,
499		     (struct sockaddr *)&sin, &size) < 0)
500		return;
501
502	if (check_loop(&sin, sep))
503		return;
504
505	result = machtime();
506	(void) sendto(s, (char *) &result, sizeof(result), 0,
507		      (struct sockaddr *)&sin, sizeof(sin));
508}
509
510/* ARGSUSED */
511void
512machtime_stream(s, sep)
513	int s;
514	struct servtab *sep;
515{
516	unsigned long result;
517
518	result = machtime();
519	(void) write(s, (char *) &result, sizeof(result));
520}
521
522/*
523 * RFC1078 TCP Port Service Multiplexer (TCPMUX). Service connections to
524 * services based on the service name sent.
525 *
526 *  Based on TCPMUX.C by Mark K. Lottor November 1988
527 *  sri-nic::ps:<mkl>tcpmux.c
528 */
529
530#define MAX_SERV_LEN	(256+2)		/* 2 bytes for \r\n */
531#define strwrite(fd, buf)	(void) write(fd, buf, sizeof(buf)-1)
532
533static int		/* # of characters upto \r,\n or \0 */
534getline(fd, buf, len)
535	int fd;
536	char *buf;
537	int len;
538{
539	int count = 0, n;
540	struct sigaction sa;
541
542	sa.sa_flags = 0;
543	sigemptyset(&sa.sa_mask);
544	sa.sa_handler = SIG_DFL;
545	sigaction(SIGALRM, &sa, (struct sigaction *)0);
546	do {
547		alarm(10);
548		n = read(fd, buf, len-count);
549		alarm(0);
550		if (n == 0)
551			return (count);
552		if (n < 0)
553			return (-1);
554		while (--n >= 0) {
555			if (*buf == '\r' || *buf == '\n' || *buf == '\0')
556				return (count);
557			count++;
558			buf++;
559		}
560	} while (count < len);
561	return (count);
562}
563
564struct servtab *
565tcpmux(s)
566	int s;
567{
568	struct servtab *sep;
569	char service[MAX_SERV_LEN+1];
570	int len;
571
572	/* Get requested service name */
573	if ((len = getline(s, service, MAX_SERV_LEN)) < 0) {
574		strwrite(s, "-Error reading service name\r\n");
575		return (NULL);
576	}
577	service[len] = '\0';
578
579	if (debug)
580		warnx("tcpmux: someone wants %s", service);
581
582	/*
583	 * Help is a required command, and lists available services,
584	 * one per line.
585	 */
586	if (!strcasecmp(service, "help")) {
587		for (sep = servtab; sep; sep = sep->se_next) {
588			if (!ISMUX(sep))
589				continue;
590			(void)write(s,sep->se_service,strlen(sep->se_service));
591			strwrite(s, "\r\n");
592		}
593		return (NULL);
594	}
595
596	/* Try matching a service in inetd.conf with the request */
597	for (sep = servtab; sep; sep = sep->se_next) {
598		if (!ISMUX(sep))
599			continue;
600		if (!strcasecmp(service, sep->se_service)) {
601			if (ISMUXPLUS(sep)) {
602				strwrite(s, "+Go\r\n");
603			}
604			return (sep);
605		}
606	}
607	strwrite(s, "-Service not available\r\n");
608	return (NULL);
609}
610