builtins.c revision 49089 
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 1.11 1999/07/24 17:06:05 green 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 and ~/.noident
307 * support.
308 */
309
310/*
311 * NOTE: If any of the asprintf()s here fail, rest assured that faulting
312 * in the buffers for using snprintf() would have also failed.
313 * Asprintf() is the proper way to do what we do.
314 */
315
316/* ARGSUSED */
317void
318iderror(lport, fport, s, er)
319	int lport, fport, s, er;
320{
321	char *p;
322
323	asprintf(&p, "%d , %d : ERROR : %s\r\n", lport, fport,
324	    er == -1 ? "HIDDEN-USER" : er ? strerror(er) : "UNKNOWN-ERROR");
325	if (p == NULL) {
326		syslog(LOG_ERR, "asprintf: %m");
327		exit(EX_OSERR);
328	}
329	write(s, p, strlen(p));
330	free(p);
331
332	exit(0);
333}
334
335/* ARGSUSED */
336void
337ident_stream(s, sep)		/* Ident service */
338	int s;
339	struct servtab *sep;
340{
341	struct utsname un;
342	struct stat sb;
343	struct sockaddr_in sin[2];
344	struct ucred uc;
345	struct timeval tv = {
346		10,
347		0
348	};
349	struct passwd *pw;
350	fd_set fdset;
351	char buf[BUFSIZE], *cp = NULL, *p, **av, *osname = NULL;
352	int len, c, fflag = 0, nflag = 0, rflag = 0, argc = 0;
353	u_short lport, fport;
354
355	inetd_setproctitle(sep->se_service, s);
356	optind = 1;
357	optreset = 1;
358	for (av = sep->se_argv; *av; av++)
359		argc++;
360	if (argc) {
361		int sec, usec;
362
363		while ((c = getopt(argc, sep->se_argv, "fno:rt:")) != -1)
364			switch (c) {
365			case 'f':
366				fflag = 1;
367				break;
368			case 'n':
369				nflag = 1;
370				break;
371			case 'o':
372				osname = optarg;
373				break;
374			case 'r':
375				rflag = 1;
376				break;
377			case 't':
378				switch (sscanf(optarg, "%d.%d", &sec, &usec)) {
379				case 2:
380					tv.tv_usec = usec;
381				case 1:
382					tv.tv_sec = sec;
383					break;
384				default:
385					if (debug)
386						warnx("bad -t argument");
387					break;
388				}
389				break;
390			default:
391				break;
392			}
393	}
394	if (osname == NULL) {
395		if (uname(&un) == -1)
396			iderror(0, 0, s, errno);
397		osname = un.sysname;
398	}
399	len = sizeof(sin[0]);
400	if (getsockname(s, (struct sockaddr *)&sin[0], &len) == -1)
401		iderror(0, 0, s, errno);
402	len = sizeof(sin[1]);
403	if (getpeername(s, (struct sockaddr *)&sin[1], &len) == -1)
404		iderror(0, 0, s, errno);
405	FD_ZERO(&fdset);
406	FD_SET(s, &fdset);
407	if (select(s + 1, &fdset, NULL, NULL, &tv) == -1)
408		iderror(0, 0, s, errno);
409	if (ioctl(s, FIONREAD, &len) == -1)
410		iderror(0, 0, s, errno);
411	if (len >= sizeof(buf))
412		len = sizeof(buf) - 1;
413	len = read(s, buf, len);
414	if (len == -1)
415		iderror(0, 0, s, errno);
416	buf[len] = '\0';
417	if (sscanf(buf, "%hu , %hu", &lport, &fport) != 2)
418		iderror(0, 0, s, 0);
419	if (!rflag)
420		iderror(lport, fport, s, -1);
421	sin[0].sin_port = htons(lport);
422	sin[1].sin_port = htons(fport);
423	len = sizeof(uc);
424	if (sysctlbyname("net.inet.tcp.getcred", &uc, &len, sin,
425	    sizeof(sin)) == -1)
426		iderror(lport, fport, s, errno);
427	pw = getpwuid(uc.cr_uid);
428	if (pw == NULL)
429		iderror(lport, fport, s, errno);
430	if (nflag) {
431		if (asprintf(&p, "%s/.noident", pw->pw_dir) == -1)
432			iderror(lport, fport, s, errno);
433		if (lstat(p, &sb) == 0) {
434			free(p);
435			iderror(lport, fport, s, -1);
436		}
437		free(p);
438	}
439	if (fflag) {
440		FILE *fakeid = NULL;
441
442		if (asprintf(&p, "%s/.fakeid", pw->pw_dir) == -1)
443			iderror(lport, fport, s, errno);
444		seteuid(pw->pw_uid);
445		setegid(pw->pw_gid);
446		fakeid = fopen(p, "r");
447		free(p);
448		if (fakeid != NULL &&
449		    fstat(fileno(fakeid), &sb) != -1 && S_ISREG(sb.st_mode)) {
450			buf[sizeof(buf) - 1] = '\0';
451			if (fgets(buf, sizeof(buf), fakeid) == NULL) {
452				cp = pw->pw_name;
453				fclose(fakeid);
454				goto printit;
455			}
456			fclose(fakeid);
457			strtok(buf, "\r\n");
458			if (strlen(buf) > 16)
459				buf[16] = '\0';
460			cp = buf;
461			while (isspace(*cp))
462				cp++;
463			strtok(cp, " \t");
464			if (!*cp || getpwnam(cp))
465				cp = getpwuid(uc.cr_uid)->pw_name;
466		} else
467			cp = pw->pw_name;
468	} else
469		cp = pw->pw_name;
470printit:
471	if (asprintf(&p, "%d , %d : USERID : %s : %s\r\n", lport, fport, osname,
472	    cp) == -1) {
473		syslog(LOG_ERR, "asprintf: %m");
474		exit(EX_OSERR);
475	}
476	write(s, p, strlen(p));
477	free(p);
478
479	exit(0);
480}
481
482/*
483 * RFC738 Time Server.
484 * Return a machine readable date and time, in the form of the
485 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
486 * returns the number of seconds since midnight, Jan 1, 1970,
487 * we must add 2208988800 seconds to this figure to make up for
488 * some seventy years Bell Labs was asleep.
489 */
490
491unsigned long
492machtime()
493{
494	struct timeval tv;
495
496	if (gettimeofday(&tv, (struct timezone *)NULL) < 0) {
497		if (debug)
498			warnx("unable to get time of day");
499		return (0L);
500	}
501#define	OFFSET ((u_long)25567 * 24*60*60)
502	return (htonl((long)(tv.tv_sec + OFFSET)));
503#undef OFFSET
504}
505
506/* ARGSUSED */
507void
508machtime_dg(s, sep)
509	int s;
510	struct servtab *sep;
511{
512	unsigned long result;
513	struct sockaddr_in sin;
514	int size;
515
516	size = sizeof(sin);
517	if (recvfrom(s, (char *)&result, sizeof(result), 0,
518		     (struct sockaddr *)&sin, &size) < 0)
519		return;
520
521	if (check_loop(&sin, sep))
522		return;
523
524	result = machtime();
525	(void) sendto(s, (char *) &result, sizeof(result), 0,
526		      (struct sockaddr *)&sin, sizeof(sin));
527}
528
529/* ARGSUSED */
530void
531machtime_stream(s, sep)
532	int s;
533	struct servtab *sep;
534{
535	unsigned long result;
536
537	result = machtime();
538	(void) write(s, (char *) &result, sizeof(result));
539}
540
541/*
542 * RFC1078 TCP Port Service Multiplexer (TCPMUX). Service connections to
543 * services based on the service name sent.
544 *
545 *  Based on TCPMUX.C by Mark K. Lottor November 1988
546 *  sri-nic::ps:<mkl>tcpmux.c
547 */
548
549#define MAX_SERV_LEN	(256+2)		/* 2 bytes for \r\n */
550#define strwrite(fd, buf)	(void) write(fd, buf, sizeof(buf)-1)
551
552static int		/* # of characters upto \r,\n or \0 */
553getline(fd, buf, len)
554	int fd;
555	char *buf;
556	int len;
557{
558	int count = 0, n;
559	struct sigaction sa;
560
561	sa.sa_flags = 0;
562	sigemptyset(&sa.sa_mask);
563	sa.sa_handler = SIG_DFL;
564	sigaction(SIGALRM, &sa, (struct sigaction *)0);
565	do {
566		alarm(10);
567		n = read(fd, buf, len-count);
568		alarm(0);
569		if (n == 0)
570			return (count);
571		if (n < 0)
572			return (-1);
573		while (--n >= 0) {
574			if (*buf == '\r' || *buf == '\n' || *buf == '\0')
575				return (count);
576			count++;
577			buf++;
578		}
579	} while (count < len);
580	return (count);
581}
582
583struct servtab *
584tcpmux(s)
585	int s;
586{
587	struct servtab *sep;
588	char service[MAX_SERV_LEN+1];
589	int len;
590
591	/* Get requested service name */
592	if ((len = getline(s, service, MAX_SERV_LEN)) < 0) {
593		strwrite(s, "-Error reading service name\r\n");
594		return (NULL);
595	}
596	service[len] = '\0';
597
598	if (debug)
599		warnx("tcpmux: someone wants %s", service);
600
601	/*
602	 * Help is a required command, and lists available services,
603	 * one per line.
604	 */
605	if (!strcasecmp(service, "help")) {
606		for (sep = servtab; sep; sep = sep->se_next) {
607			if (!ISMUX(sep))
608				continue;
609			(void)write(s,sep->se_service,strlen(sep->se_service));
610			strwrite(s, "\r\n");
611		}
612		return (NULL);
613	}
614
615	/* Try matching a service in inetd.conf with the request */
616	for (sep = servtab; sep; sep = sep->se_next) {
617		if (!ISMUX(sep))
618			continue;
619		if (!strcasecmp(service, sep->se_service)) {
620			if (ISMUXPLUS(sep)) {
621				strwrite(s, "+Go\r\n");
622			}
623			return (sep);
624		}
625	}
626	strwrite(s, "-Service not available\r\n");
627	return (NULL);
628}
629