builtins.c revision 49052 
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 1.8 1999/07/24 12:35:50 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 passwd *pw;
337	struct timeval tv = {
338		10,
339		0
340	};
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		while ((c = getopt(argc, sep->se_argv, "fro:t:")) != -1)
353			switch (c) {
354			case 'f':
355				fflag = 1;
356				break;
357			case 'r':
358				rflag = 1;
359				break;
360			case 'o':
361				osname = optarg;
362				break;
363			case 't':
364			{
365				int sec, usec;
366
367				switch (sscanf(optarg, "%d.%d", &sec, &usec)) {
368				case 2:
369					tv.tv_usec = usec;
370				case 1:
371					tv.tv_sec = sec;
372					break;
373				default:
374					if (debug)
375						warnx("bad -t argument");
376					break;
377				}
378			}
379			default:
380				break;
381			}
382	}
383	if (osname == NULL) {
384		struct utsname un;
385
386		if (uname(&un) == -1)
387			iderror(0, 0, s, errno);
388		osname = un.sysname;
389	}
390	len = sizeof(sin[0]);
391	if (getsockname(s, (struct sockaddr *)&sin[0], &len) == -1)
392		iderror(0, 0, s, errno);
393	len = sizeof(sin[1]);
394	if (getpeername(s, (struct sockaddr *)&sin[1], &len) == -1)
395		iderror(0, 0, s, errno);
396	FD_ZERO(&fdset);
397	FD_SET(s, &fdset);
398	if (select(s + 1, &fdset, NULL, NULL, &tv) == -1)
399		iderror(0, 0, s, errno);
400	if (ioctl(s, FIONREAD, &len) == -1)
401		iderror(0, 0, s, errno);
402	if (len >= sizeof(buf))
403		len = sizeof(buf) - 1;
404	len = read(s, buf, len);
405	if (len == -1)
406		iderror(0, 0, s, errno);
407	buf[len] = '\0';
408	if (sscanf(buf, "%hu , %hu", &lport, &fport) != 2)
409		iderror(0, 0, s, 0);
410	if (!rflag)
411		iderror(lport, fport, s, -1);
412	sin[0].sin_port = htons(lport);
413	sin[1].sin_port = htons(fport);
414	len = sizeof(uc);
415	if (sysctlbyname("net.inet.tcp.getcred", &uc, &len, sin,
416	    sizeof(sin)) == -1)
417		iderror(lport, fport, s, errno);
418	pw = getpwuid(uc.cr_uid);
419	if (pw == NULL)
420		iderror(lport, fport, s, errno);
421	if (fflag) {
422		FILE *fakeid = NULL;
423		char fakeid_path[PATH_MAX];
424		struct stat sb;
425
426		seteuid(pw->pw_uid);
427		setegid(pw->pw_gid);
428		snprintf(fakeid_path, sizeof(fakeid_path), "%s/.fakeid",
429		    pw->pw_dir);
430		if ((fakeid = fopen(fakeid_path, "r")) != NULL &&
431		    fstat(fileno(fakeid), &sb) != -1 && S_ISREG(sb.st_mode)) {
432			buf[sizeof(buf) - 1] = '\0';
433			if (fgets(buf, sizeof(buf), fakeid) == NULL) {
434				cp = pw->pw_name;
435				fclose(fakeid);
436				goto printit;
437			}
438			fclose(fakeid);
439			strtok(buf, "\r\n");
440			if (strlen(buf) > 16)
441				buf[16] = '\0';
442			cp = buf;
443			while (isspace(*cp))
444				cp++;
445			strtok(cp, " \t");
446			if (!*cp || getpwnam(cp))
447				cp = getpwuid(uc.cr_uid)->pw_name;
448		} else
449			cp = pw->pw_name;
450	} else
451		cp = pw->pw_name;
452printit:
453	if (asprintf(&p, "%d , %d : USERID : %s : %s\r\n", lport, fport, osname,
454	    cp) == -1) {
455		syslog(LOG_ERR, "Out of memory.");
456		exit(EX_OSERR);
457	}
458	write(s, p, strlen(p));
459	free(p);
460
461	exit(0);
462}
463
464/*
465 * RFC738 Time Server.
466 * Return a machine readable date and time, in the form of the
467 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
468 * returns the number of seconds since midnight, Jan 1, 1970,
469 * we must add 2208988800 seconds to this figure to make up for
470 * some seventy years Bell Labs was asleep.
471 */
472
473unsigned long
474machtime()
475{
476	struct timeval tv;
477
478	if (gettimeofday(&tv, (struct timezone *)NULL) < 0) {
479		if (debug)
480			warnx("unable to get time of day");
481		return (0L);
482	}
483#define	OFFSET ((u_long)25567 * 24*60*60)
484	return (htonl((long)(tv.tv_sec + OFFSET)));
485#undef OFFSET
486}
487
488/* ARGSUSED */
489void
490machtime_dg(s, sep)
491	int s;
492	struct servtab *sep;
493{
494	unsigned long result;
495	struct sockaddr_in sin;
496	int size;
497
498	size = sizeof(sin);
499	if (recvfrom(s, (char *)&result, sizeof(result), 0,
500		     (struct sockaddr *)&sin, &size) < 0)
501		return;
502
503	if (check_loop(&sin, sep))
504		return;
505
506	result = machtime();
507	(void) sendto(s, (char *) &result, sizeof(result), 0,
508		      (struct sockaddr *)&sin, sizeof(sin));
509}
510
511/* ARGSUSED */
512void
513machtime_stream(s, sep)
514	int s;
515	struct servtab *sep;
516{
517	unsigned long result;
518
519	result = machtime();
520	(void) write(s, (char *) &result, sizeof(result));
521}
522
523/*
524 * RFC1078 TCP Port Service Multiplexer (TCPMUX). Service connections to
525 * services based on the service name sent.
526 *
527 *  Based on TCPMUX.C by Mark K. Lottor November 1988
528 *  sri-nic::ps:<mkl>tcpmux.c
529 */
530
531#define MAX_SERV_LEN	(256+2)		/* 2 bytes for \r\n */
532#define strwrite(fd, buf)	(void) write(fd, buf, sizeof(buf)-1)
533
534static int		/* # of characters upto \r,\n or \0 */
535getline(fd, buf, len)
536	int fd;
537	char *buf;
538	int len;
539{
540	int count = 0, n;
541	struct sigaction sa;
542
543	sa.sa_flags = 0;
544	sigemptyset(&sa.sa_mask);
545	sa.sa_handler = SIG_DFL;
546	sigaction(SIGALRM, &sa, (struct sigaction *)0);
547	do {
548		alarm(10);
549		n = read(fd, buf, len-count);
550		alarm(0);
551		if (n == 0)
552			return (count);
553		if (n < 0)
554			return (-1);
555		while (--n >= 0) {
556			if (*buf == '\r' || *buf == '\n' || *buf == '\0')
557				return (count);
558			count++;
559			buf++;
560		}
561	} while (count < len);
562	return (count);
563}
564
565struct servtab *
566tcpmux(s)
567	int s;
568{
569	struct servtab *sep;
570	char service[MAX_SERV_LEN+1];
571	int len;
572
573	/* Get requested service name */
574	if ((len = getline(s, service, MAX_SERV_LEN)) < 0) {
575		strwrite(s, "-Error reading service name\r\n");
576		return (NULL);
577	}
578	service[len] = '\0';
579
580	if (debug)
581		warnx("tcpmux: someone wants %s", service);
582
583	/*
584	 * Help is a required command, and lists available services,
585	 * one per line.
586	 */
587	if (!strcasecmp(service, "help")) {
588		for (sep = servtab; sep; sep = sep->se_next) {
589			if (!ISMUX(sep))
590				continue;
591			(void)write(s,sep->se_service,strlen(sep->se_service));
592			strwrite(s, "\r\n");
593		}
594		return (NULL);
595	}
596
597	/* Try matching a service in inetd.conf with the request */
598	for (sep = servtab; sep; sep = sep->se_next) {
599		if (!ISMUX(sep))
600			continue;
601		if (!strcasecmp(service, sep->se_service)) {
602			if (ISMUXPLUS(sep)) {
603				strwrite(s, "+Go\r\n");
604			}
605			return (sep);
606		}
607	}
608	strwrite(s, "-Service not available\r\n");
609	return (NULL);
610}
611