builtins.c revision 91354 
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 * $FreeBSD: head/usr.sbin/inetd/builtins.c 91354 2002-02-27 04:45:37Z dd $
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 <fcntl.h>
44#include <limits.h>
45#include <pwd.h>
46#include <signal.h>
47#include <stdlib.h>
48#include <string.h>
49#include <sysexits.h>
50#include <syslog.h>
51#include <unistd.h>
52
53#include "inetd.h"
54
55void		chargen_dg __P((int, struct servtab *));
56void		chargen_stream __P((int, struct servtab *));
57void		daytime_dg __P((int, struct servtab *));
58void		daytime_stream __P((int, struct servtab *));
59void		discard_dg __P((int, struct servtab *));
60void		discard_stream __P((int, struct servtab *));
61void		echo_dg __P((int, struct servtab *));
62void		echo_stream __P((int, struct servtab *));
63static int	getline __P((int, char *, int));
64void		iderror __P((int, int, int, const char *));
65void		ident_stream __P((int, struct servtab *));
66void		initring __P((void));
67unsigned long	machtime __P((void));
68void		machtime_dg __P((int, struct servtab *));
69void		machtime_stream __P((int, struct servtab *));
70
71char ring[128];
72char *endring;
73
74
75struct biltin biltins[] = {
76	/* Echo received data */
77	{ "echo",	SOCK_STREAM,	1, -1,	echo_stream },
78	{ "echo",	SOCK_DGRAM,	0, 1,	echo_dg },
79
80	/* Internet /dev/null */
81	{ "discard",	SOCK_STREAM,	1, -1,	discard_stream },
82	{ "discard",	SOCK_DGRAM,	0, 1,	discard_dg },
83
84	/* Return 32 bit time since 1900 */
85	{ "time",	SOCK_STREAM,	0, -1,	machtime_stream },
86	{ "time",	SOCK_DGRAM,	0, 1,	machtime_dg },
87
88	/* Return human-readable time */
89	{ "daytime",	SOCK_STREAM,	0, -1,	daytime_stream },
90	{ "daytime",	SOCK_DGRAM,	0, 1,	daytime_dg },
91
92	/* Familiar character generator */
93	{ "chargen",	SOCK_STREAM,	1, -1,	chargen_stream },
94	{ "chargen",	SOCK_DGRAM,	0, 1,	chargen_dg },
95
96	{ "tcpmux",	SOCK_STREAM,	1, -1,	(bi_fn_t *)tcpmux },
97
98	{ "auth",	SOCK_STREAM,	1, -1,	ident_stream },
99
100	{ NULL,		0,		0, 0,	NULL }
101};
102
103/*
104 * RFC864 Character Generator Protocol. Generates character data without
105 * any regard for input.
106 */
107
108void
109initring()
110{
111	int i;
112
113	endring = ring;
114
115	for (i = 0; i <= 128; ++i)
116		if (isprint(i))
117			*endring++ = i;
118}
119
120/* ARGSUSED */
121void
122chargen_dg(s, sep)		/* Character generator */
123	int s;
124	struct servtab *sep;
125{
126	struct sockaddr_storage ss;
127	static char *rs;
128	int len;
129	socklen_t size;
130	char text[LINESIZ+2];
131
132	if (endring == 0) {
133		initring();
134		rs = ring;
135	}
136
137	size = sizeof(ss);
138	if (recvfrom(s, text, sizeof(text), 0,
139		     (struct sockaddr *)&ss, &size) < 0)
140		return;
141
142	if (check_loop((struct sockaddr *)&ss, sep))
143		return;
144
145	if ((len = endring - rs) >= LINESIZ)
146		memmove(text, rs, LINESIZ);
147	else {
148		memmove(text, rs, len);
149		memmove(text + len, ring, LINESIZ - len);
150	}
151	if (++rs == endring)
152		rs = ring;
153	text[LINESIZ] = '\r';
154	text[LINESIZ + 1] = '\n';
155	(void) sendto(s, text, sizeof(text), 0, (struct sockaddr *)&ss, size);
156}
157
158/* ARGSUSED */
159void
160chargen_stream(s, sep)		/* Character generator */
161	int s;
162	struct servtab *sep;
163{
164	int len;
165	char *rs, text[LINESIZ+2];
166
167	inetd_setproctitle(sep->se_service, s);
168
169	if (!endring) {
170		initring();
171		rs = ring;
172	}
173
174	text[LINESIZ] = '\r';
175	text[LINESIZ + 1] = '\n';
176	for (rs = ring;;) {
177		if ((len = endring - rs) >= LINESIZ)
178			memmove(text, rs, LINESIZ);
179		else {
180			memmove(text, rs, len);
181			memmove(text + len, ring, LINESIZ - len);
182		}
183		if (++rs == endring)
184			rs = ring;
185		if (write(s, text, sizeof(text)) != sizeof(text))
186			break;
187	}
188	exit(0);
189}
190
191/*
192 * RFC867 Daytime Protocol. Sends the current date and time as an ascii
193 * character string without any regard for input.
194 */
195
196/* ARGSUSED */
197void
198daytime_dg(s, sep)		/* Return human-readable time of day */
199	int s;
200	struct servtab *sep;
201{
202	char buffer[256];
203	time_t now;
204	struct sockaddr_storage ss;
205	socklen_t size;
206
207	now = time((time_t *) 0);
208
209	size = sizeof(ss);
210	if (recvfrom(s, buffer, sizeof(buffer), 0,
211		     (struct sockaddr *)&ss, &size) < 0)
212		return;
213
214	if (check_loop((struct sockaddr *)&ss, sep))
215		return;
216
217	(void) sprintf(buffer, "%.24s\r\n", ctime(&now));
218	(void) sendto(s, buffer, strlen(buffer), 0,
219		      (struct sockaddr *)&ss, size);
220}
221
222/* ARGSUSED */
223void
224daytime_stream(s, sep)		/* Return human-readable time of day */
225	int s;
226	struct servtab *sep __unused;
227{
228	char buffer[256];
229	time_t now;
230
231	now = time((time_t *) 0);
232
233	(void) sprintf(buffer, "%.24s\r\n", ctime(&now));
234	(void) send(s, buffer, strlen(buffer), MSG_EOF);
235}
236
237/*
238 * RFC863 Discard Protocol. Any data received is thrown away and no response
239 * is sent.
240 */
241
242/* ARGSUSED */
243void
244discard_dg(s, sep)		/* Discard service -- ignore data */
245	int s;
246	struct servtab *sep __unused;
247{
248	char buffer[BUFSIZE];
249
250	(void) read(s, buffer, sizeof(buffer));
251}
252
253/* ARGSUSED */
254void
255discard_stream(s, sep)		/* Discard service -- ignore data */
256	int s;
257	struct servtab *sep;
258{
259	int ret;
260	char buffer[BUFSIZE];
261
262	inetd_setproctitle(sep->se_service, s);
263	while (1) {
264		while ((ret = read(s, buffer, sizeof(buffer))) > 0)
265			;
266		if (ret == 0 || errno != EINTR)
267			break;
268	}
269	exit(0);
270}
271
272/*
273 * RFC862 Echo Protocol. Any data received is sent back to the sender as
274 * received.
275 */
276
277/* ARGSUSED */
278void
279echo_dg(s, sep)			/* Echo service -- echo data back */
280	int s;
281	struct servtab *sep;
282{
283	char buffer[65536]; /* Should be sizeof(max datagram). */
284	int i;
285	socklen_t size;
286	struct sockaddr_storage ss;
287
288	size = sizeof(ss);
289	if ((i = recvfrom(s, buffer, sizeof(buffer), 0,
290			  (struct sockaddr *)&ss, &size)) < 0)
291		return;
292
293	if (check_loop((struct sockaddr *)&ss, sep))
294		return;
295
296	(void) sendto(s, buffer, i, 0, (struct sockaddr *)&ss, size);
297}
298
299/* ARGSUSED */
300void
301echo_stream(s, sep)		/* Echo service -- echo data back */
302	int s;
303	struct servtab *sep;
304{
305	char buffer[BUFSIZE];
306	int i;
307
308	inetd_setproctitle(sep->se_service, s);
309	while ((i = read(s, buffer, sizeof(buffer))) > 0 &&
310	    write(s, buffer, i) > 0)
311		;
312	exit(0);
313}
314
315/*
316 * RFC1413 Identification Protocol. Given a TCP port number pair, return a
317 * character string which identifies the owner of that connection on the
318 * server's system. Extended to allow for ~/.fakeid support and ~/.noident
319 * support.
320 */
321
322/* RFC 1413 says the following are the only errors you can return. */
323#define ID_INVALID	"INVALID-PORT"	/* Port number improperly specified. */
324#define ID_NOUSER	"NO-USER"	/* Port not in use/not identifable. */
325#define ID_HIDDEN	"HIDDEN-USER"	/* Hiden at user's request. */
326#define ID_UNKNOWN	"UNKNOWN-ERROR"	/* Everything else. */
327
328/* ARGSUSED */
329void
330iderror(lport, fport, s, er)	/* Generic ident_stream error-sending func */
331	int lport, fport, s;
332	const char *er;
333{
334	char *p;
335
336	asprintf(&p, "%d , %d : ERROR : %s\r\n", lport, fport, er);
337	if (p == NULL) {
338		syslog(LOG_ERR, "asprintf: %m");
339		exit(EX_OSERR);
340	}
341	send(s, p, strlen(p), MSG_EOF);
342	free(p);
343
344	exit(0);
345}
346
347/* ARGSUSED */
348void
349ident_stream(s, sep)		/* Ident service (AKA "auth") */
350	int s;
351	struct servtab *sep;
352{
353	struct utsname un;
354	struct stat sb;
355	struct sockaddr_in sin4[2];
356#ifdef INET6
357	struct sockaddr_in6 sin6[2];
358#endif
359	struct sockaddr_storage ss[2];
360	struct xucred uc;
361	struct timeval tv = {
362		10,
363		0
364	}, to;
365	struct passwd *pw = NULL;
366	fd_set fdset;
367	char buf[BUFSIZE], *p, **av, *osname = NULL, e;
368	char idbuf[MAXLOGNAME] = ""; /* Big enough to hold uid in decimal. */
369	socklen_t socklen;
370	ssize_t ssize;
371	size_t size, bufsiz;
372	int c, fflag = 0, nflag = 0, rflag = 0, argc = 0;
373	int gflag = 0, iflag = 0, Fflag = 0, getcredfail = 0, onreadlen;
374	u_short lport, fport;
375
376	inetd_setproctitle(sep->se_service, s);
377	/*
378	 * Reset getopt() since we are a fork() but not an exec() from
379	 * a parent which used getopt() already.
380	 */
381	optind = 1;
382	optreset = 1;
383	/*
384	 * Take the internal argument vector and count it out to make an
385	 * argument count for getopt. This can be used for any internal
386	 * service to read arguments and use getopt() easily.
387	 */
388	for (av = sep->se_argv; *av; av++)
389		argc++;
390	if (argc) {
391		int sec, usec;
392		size_t i;
393		u_int32_t rnd32;
394
395		while ((c = getopt(argc, sep->se_argv, "d:fFgino:rt:")) != -1)
396			switch (c) {
397			case 'd':
398				if (!gflag)
399					strlcpy(idbuf, optarg, sizeof(idbuf));
400				break;
401			case 'f':
402				fflag = 1;
403				break;
404			case 'F':
405				fflag = 1;
406				Fflag=1;
407				break;
408			case 'g':
409				gflag = 1;
410				rnd32 = 0;	/* Shush, compiler. */
411				/*
412				 * The number of bits in "rnd32" divided
413				 * by the number of bits needed per iteration
414				 * gives a more optimal way to reload the
415				 * random number only when necessary.
416				 *
417				 * 32 bits from arc4random corrisponds to
418				 * about 6 base-36 digits, so we reseed evey 6.
419				 */
420				for (i = 0; i < sizeof(idbuf) - 1; i++) {
421					static const char *const base36 =
422					    "0123456789"
423					    "abcdefghijklmnopqrstuvwxyz";
424					if (i % 6 == 0)
425						rnd32 = arc4random();
426					idbuf[i] = base36[rnd32 % 36];
427					rnd32 /= 36;
428				}
429				idbuf[i] = '\0';
430				break;
431			case 'i':
432				iflag = 1;
433				break;
434			case 'n':
435				nflag = 1;
436				break;
437			case 'o':
438				osname = optarg;
439				break;
440			case 'r':
441				rflag = 1;
442				break;
443			case 't':
444				switch (sscanf(optarg, "%d.%d", &sec, &usec)) {
445				case 2:
446					tv.tv_usec = usec;
447					/* FALLTHROUGH */
448				case 1:
449					tv.tv_sec = sec;
450					break;
451				default:
452					if (debug)
453						warnx("bad -t argument");
454					break;
455				}
456				break;
457			default:
458				break;
459			}
460	}
461	if (osname == NULL) {
462		if (uname(&un) == -1)
463			iderror(0, 0, s, ID_UNKNOWN);
464		osname = un.sysname;
465	}
466
467	/*
468	 * We're going to prepare for and execute reception of a
469	 * packet of data from the user. The data is in the format
470	 * "local_port , foreign_port\r\n" (with local being the
471	 * server's port and foreign being the client's.)
472	 */
473	gettimeofday(&to, NULL);
474	to.tv_sec += tv.tv_sec;
475	to.tv_usec += tv.tv_usec;
476	if (to.tv_usec >= 1000000) {
477		to.tv_usec -= 1000000;
478		to.tv_sec++;
479	}
480
481	size = 0;
482	bufsiz = sizeof(buf) - 1;
483	FD_ZERO(&fdset);
484 	while (bufsiz > 0) {
485		gettimeofday(&tv, NULL);
486		tv.tv_sec = to.tv_sec - tv.tv_sec;
487		tv.tv_usec = to.tv_usec - tv.tv_usec;
488		if (tv.tv_usec < 0) {
489			tv.tv_usec += 1000000;
490			tv.tv_sec--;
491		}
492		if (tv.tv_sec < 0)
493			break;
494		FD_SET(s, &fdset);
495		if (select(s + 1, &fdset, NULL, NULL, &tv) == -1)
496			iderror(0, 0, s, ID_UNKNOWN);
497		if (ioctl(s, FIONREAD, &onreadlen) == -1)
498			iderror(0, 0, s, ID_UNKNOWN);
499		if ((size_t)onreadlen > bufsiz)
500			onreadlen = bufsiz;
501		ssize = read(s, &buf[size], (size_t)onreadlen);
502		if (ssize == -1)
503			iderror(0, 0, s, ID_UNKNOWN);
504		else if (ssize == 0)
505			break;
506		bufsiz -= ssize;
507		size += ssize;
508		if (memchr(&buf[size - ssize], '\n', ssize) != NULL)
509			break;
510 	}
511	buf[size] = '\0';
512	/* Read two characters, and check for a delimiting character */
513	if (sscanf(buf, "%hu , %hu%c", &lport, &fport, &e) != 3 || isdigit(e))
514		iderror(0, 0, s, ID_INVALID);
515
516	/* Send garbage? */
517	if (gflag)
518		goto printit;
519
520	/*
521	 * If not "real" (-r), send a HIDDEN-USER error for everything.
522	 * If -d is used to set a fallback username, this is used to
523	 * override it, and the fallback is returned instead.
524	 */
525	if (!rflag) {
526		if (*idbuf == '\0')
527			iderror(lport, fport, s, ID_HIDDEN);
528		goto printit;
529	}
530
531	/*
532	 * We take the input and construct an array of two sockaddr_ins
533	 * which contain the local address information and foreign
534	 * address information, respectively, used to look up the
535	 * credentials for the socket (which are returned by the
536	 * sysctl "net.inet.tcp.getcred" when we call it.)
537	 */
538	socklen = sizeof(ss[0]);
539	if (getsockname(s, (struct sockaddr *)&ss[0], &socklen) == -1)
540		iderror(lport, fport, s, ID_UNKNOWN);
541	socklen = sizeof(ss[1]);
542	if (getpeername(s, (struct sockaddr *)&ss[1], &socklen) == -1)
543		iderror(lport, fport, s, ID_UNKNOWN);
544	if (ss[0].ss_family != ss[1].ss_family)
545		iderror(lport, fport, s, ID_UNKNOWN);
546	size = sizeof(uc);
547	switch (ss[0].ss_family) {
548	case AF_INET:
549		sin4[0] = *(struct sockaddr_in *)&ss[0];
550		sin4[0].sin_port = htons(lport);
551		sin4[1] = *(struct sockaddr_in *)&ss[1];
552		sin4[1].sin_port = htons(fport);
553		if (sysctlbyname("net.inet.tcp.getcred", &uc, &size, sin4,
554				 sizeof(sin4)) == -1)
555			getcredfail = errno;
556		break;
557#ifdef INET6
558	case AF_INET6:
559		sin6[0] = *(struct sockaddr_in6 *)&ss[0];
560		sin6[0].sin6_port = htons(lport);
561		sin6[1] = *(struct sockaddr_in6 *)&ss[1];
562		sin6[1].sin6_port = htons(fport);
563		if (sysctlbyname("net.inet6.tcp6.getcred", &uc, &size, sin6,
564				 sizeof(sin6)) == -1)
565			getcredfail = errno;
566		break;
567#endif
568	default: /* should not reach here */
569		getcredfail = EAFNOSUPPORT;
570		break;
571	}
572	if (getcredfail != 0 || uc.cr_version != XUCRED_VERSION) {
573		if (*idbuf == '\0')
574			iderror(lport, fport, s,
575			    getcredfail == ENOENT ? ID_NOUSER : ID_UNKNOWN);
576		goto printit;
577	}
578
579	/* Look up the pw to get the username and home directory*/
580	errno = 0;
581	pw = getpwuid(uc.cr_uid);
582	if (pw == NULL)
583		iderror(lport, fport, s, errno == 0 ? ID_NOUSER : ID_UNKNOWN);
584
585	if (iflag)
586		snprintf(idbuf, sizeof(idbuf), "%u", (unsigned)pw->pw_uid);
587	else
588		strlcpy(idbuf, pw->pw_name, sizeof(idbuf));
589
590	/*
591	 * If enabled, we check for a file named ".noident" in the user's
592	 * home directory. If found, we return HIDDEN-USER.
593	 */
594	if (nflag) {
595		if (asprintf(&p, "%s/.noident", pw->pw_dir) == -1)
596			iderror(lport, fport, s, ID_UNKNOWN);
597		if (lstat(p, &sb) == 0) {
598			free(p);
599			iderror(lport, fport, s, ID_HIDDEN);
600		}
601		free(p);
602	}
603
604	/*
605	 * Here, if enabled, we read a user's ".fakeid" file in their
606	 * home directory. It consists of a line containing the name
607	 * they want.
608	 */
609	if (fflag) {
610		int fakeid_fd;
611
612		/*
613		 * Here we set ourself to effectively be the user, so we don't
614		 * open any files we have no permission to open, especially
615		 * symbolic links to sensitive root-owned files or devices.
616		 */
617		if (initgroups(pw->pw_name, pw->pw_gid) == -1)
618			iderror(lport, fport, s, ID_UNKNOWN);
619		if (seteuid(pw->pw_uid) == -1)
620			iderror(lport, fport, s, ID_UNKNOWN);
621		/*
622		 * We can't stat() here since that would be a race
623		 * condition.
624		 * Therefore, we open the file we have permissions to open
625		 * and if it's not a regular file, we close it and end up
626		 * returning the user's real username.
627		 */
628		if (asprintf(&p, "%s/.fakeid", pw->pw_dir) == -1)
629			iderror(lport, fport, s, ID_UNKNOWN);
630		fakeid_fd = open(p, O_RDONLY | O_NONBLOCK);
631		free(p);
632		if (fakeid_fd == -1 || fstat(fakeid_fd, &sb) == -1 ||
633		    !S_ISREG(sb.st_mode))
634			goto fakeid_fail;
635
636		if ((ssize = read(fakeid_fd, buf, sizeof(buf) - 1)) < 0)
637			goto fakeid_fail;
638		buf[ssize] = '\0';
639
640		/*
641		 * Usually, the file will have the desired identity
642		 * in the form "identity\n". Allow for leading white
643		 * space and trailing white space/end of line.
644		 */
645		p = buf;
646		p += strspn(p, " \t");
647		p[strcspn(p, " \t\r\n")] = '\0';
648		if (strlen(p) > MAXLOGNAME - 1) /* Too long (including nul)? */
649			p[MAXLOGNAME - 1] = '\0';
650
651		/*
652		 * If the name is a zero-length string or matches it
653		 * the id or name of another user (unless permitted by -F)
654		 * then it is invalid.
655		 */
656		if (*p == '\0')
657			goto fakeid_fail;
658		if (!Fflag) {
659			if (iflag) {
660				if (p[strspn(p, "0123456789")] == '\0' &&
661				    getpwuid(atoi(p)) != NULL)
662					goto fakeid_fail;
663			} else {
664				if (getpwnam(p) != NULL)
665					goto fakeid_fail;
666			}
667		}
668
669		strlcpy(idbuf, p, sizeof(idbuf));
670
671fakeid_fail:
672		if (fakeid_fd != -1)
673			close(fakeid_fd);
674	}
675
676printit:
677	/* Finally, we make and send the reply. */
678	if (asprintf(&p, "%d , %d : USERID : %s : %s\r\n", lport, fport, osname,
679	    idbuf) == -1) {
680		syslog(LOG_ERR, "asprintf: %m");
681		exit(EX_OSERR);
682	}
683	send(s, p, strlen(p), MSG_EOF);
684	free(p);
685
686	exit(0);
687}
688
689/*
690 * RFC738 Time Server.
691 * Return a machine readable date and time, in the form of the
692 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
693 * returns the number of seconds since midnight, Jan 1, 1970,
694 * we must add 2208988800 seconds to this figure to make up for
695 * some seventy years Bell Labs was asleep.
696 */
697
698unsigned long
699machtime()
700{
701	struct timeval tv;
702
703	if (gettimeofday(&tv, (struct timezone *)NULL) < 0) {
704		if (debug)
705			warnx("unable to get time of day");
706		return (0L);
707	}
708#define	OFFSET ((u_long)25567 * 24*60*60)
709	return (htonl((long)(tv.tv_sec + OFFSET)));
710#undef OFFSET
711}
712
713/* ARGSUSED */
714void
715machtime_dg(s, sep)
716	int s;
717	struct servtab *sep;
718{
719	unsigned long result;
720	struct sockaddr_storage ss;
721	socklen_t size;
722
723	size = sizeof(ss);
724	if (recvfrom(s, (char *)&result, sizeof(result), 0,
725		     (struct sockaddr *)&ss, &size) < 0)
726		return;
727
728	if (check_loop((struct sockaddr *)&ss, sep))
729		return;
730
731	result = machtime();
732	(void) sendto(s, (char *) &result, sizeof(result), 0,
733		      (struct sockaddr *)&ss, size);
734}
735
736/* ARGSUSED */
737void
738machtime_stream(s, sep)
739	int s;
740	struct servtab *sep __unused;
741{
742	unsigned long result;
743
744	result = machtime();
745	(void) send(s, (char *) &result, sizeof(result), MSG_EOF);
746}
747
748/*
749 * RFC1078 TCP Port Service Multiplexer (TCPMUX). Service connections to
750 * services based on the service name sent.
751 *
752 *  Based on TCPMUX.C by Mark K. Lottor November 1988
753 *  sri-nic::ps:<mkl>tcpmux.c
754 */
755
756#define MAX_SERV_LEN	(256+2)		/* 2 bytes for \r\n */
757#define strwrite(fd, buf)	(void) write(fd, buf, sizeof(buf)-1)
758
759static int		/* # of characters upto \r,\n or \0 */
760getline(fd, buf, len)
761	int fd;
762	char *buf;
763	int len;
764{
765	int count = 0, n;
766	struct sigaction sa;
767
768	sa.sa_flags = 0;
769	sigemptyset(&sa.sa_mask);
770	sa.sa_handler = SIG_DFL;
771	sigaction(SIGALRM, &sa, (struct sigaction *)0);
772	do {
773		alarm(10);
774		n = read(fd, buf, len-count);
775		alarm(0);
776		if (n == 0)
777			return (count);
778		if (n < 0)
779			return (-1);
780		while (--n >= 0) {
781			if (*buf == '\r' || *buf == '\n' || *buf == '\0')
782				return (count);
783			count++;
784			buf++;
785		}
786	} while (count < len);
787	return (count);
788}
789
790struct servtab *
791tcpmux(s)
792	int s;
793{
794	struct servtab *sep;
795	char service[MAX_SERV_LEN+1];
796	int len;
797
798	/* Get requested service name */
799	if ((len = getline(s, service, MAX_SERV_LEN)) < 0) {
800		strwrite(s, "-Error reading service name\r\n");
801		return (NULL);
802	}
803	service[len] = '\0';
804
805	if (debug)
806		warnx("tcpmux: someone wants %s", service);
807
808	/*
809	 * Help is a required command, and lists available services,
810	 * one per line.
811	 */
812	if (!strcasecmp(service, "help")) {
813		for (sep = servtab; sep; sep = sep->se_next) {
814			if (!ISMUX(sep))
815				continue;
816			(void)write(s,sep->se_service,strlen(sep->se_service));
817			strwrite(s, "\r\n");
818		}
819		return (NULL);
820	}
821
822	/* Try matching a service in inetd.conf with the request */
823	for (sep = servtab; sep; sep = sep->se_next) {
824		if (!ISMUX(sep))
825			continue;
826		if (!strcasecmp(service, sep->se_service)) {
827			if (ISMUXPLUS(sep)) {
828				strwrite(s, "+Go\r\n");
829			}
830			return (sep);
831		}
832	}
833	strwrite(s, "-Service not available\r\n");
834	return (NULL);
835}
836