builtins.c revision 49033 
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 1.6 1999/07/23 15:26:42 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
91void
92initring()
93{
94	int i;
95
96	endring = ring;
97
98	for (i = 0; i <= 128; ++i)
99		if (isprint(i))
100			*endring++ = i;
101}
102
103/* ARGSUSED */
104void
105chargen_dg(s, sep)		/* Character generator */
106	int s;
107	struct servtab *sep;
108{
109	struct sockaddr_in sin;
110	static char *rs;
111	int len, size;
112	char text[LINESIZ+2];
113
114	if (endring == 0) {
115		initring();
116		rs = ring;
117	}
118
119	size = sizeof(sin);
120	if (recvfrom(s, text, sizeof(text), 0,
121		     (struct sockaddr *)&sin, &size) < 0)
122		return;
123
124	if (check_loop(&sin, sep))
125		return;
126
127	if ((len = endring - rs) >= LINESIZ)
128		memmove(text, rs, LINESIZ);
129	else {
130		memmove(text, rs, len);
131		memmove(text + len, ring, LINESIZ - len);
132	}
133	if (++rs == endring)
134		rs = ring;
135	text[LINESIZ] = '\r';
136	text[LINESIZ + 1] = '\n';
137	(void) sendto(s, text, sizeof(text), 0,
138		      (struct sockaddr *)&sin, sizeof(sin));
139}
140
141/* ARGSUSED */
142void
143chargen_stream(s, sep)		/* Character generator */
144	int s;
145	struct servtab *sep;
146{
147	int len;
148	char *rs, text[LINESIZ+2];
149
150	inetd_setproctitle(sep->se_service, s);
151
152	if (!endring) {
153		initring();
154		rs = ring;
155	}
156
157	text[LINESIZ] = '\r';
158	text[LINESIZ + 1] = '\n';
159	for (rs = ring;;) {
160		if ((len = endring - rs) >= LINESIZ)
161			memmove(text, rs, LINESIZ);
162		else {
163			memmove(text, rs, len);
164			memmove(text + len, ring, LINESIZ - len);
165		}
166		if (++rs == endring)
167			rs = ring;
168		if (write(s, text, sizeof(text)) != sizeof(text))
169			break;
170	}
171	exit(0);
172}
173
174/* ARGSUSED */
175void
176daytime_dg(s, sep)		/* Return human-readable time of day */
177	int s;
178	struct servtab *sep;
179{
180	char buffer[256];
181	time_t clock;
182	struct sockaddr_in sin;
183	int size;
184
185	clock = time((time_t *) 0);
186
187	size = sizeof(sin);
188	if (recvfrom(s, buffer, sizeof(buffer), 0,
189		     (struct sockaddr *)&sin, &size) < 0)
190		return;
191
192	if (check_loop(&sin, sep))
193		return;
194
195	(void) sprintf(buffer, "%.24s\r\n", ctime(&clock));
196	(void) sendto(s, buffer, strlen(buffer), 0,
197		      (struct sockaddr *)&sin, sizeof(sin));
198}
199
200/* ARGSUSED */
201void
202daytime_stream(s, sep)		/* Return human-readable time of day */
203	int s;
204	struct servtab *sep;
205{
206	char buffer[256];
207	time_t clock;
208
209	clock = time((time_t *) 0);
210
211	(void) sprintf(buffer, "%.24s\r\n", ctime(&clock));
212	(void) write(s, buffer, strlen(buffer));
213}
214
215/* ARGSUSED */
216void
217discard_dg(s, sep)		/* Discard service -- ignore data */
218	int s;
219	struct servtab *sep;
220{
221	char buffer[BUFSIZE];
222
223	(void) read(s, buffer, sizeof(buffer));
224}
225
226/* ARGSUSED */
227void
228discard_stream(s, sep)		/* Discard service -- ignore data */
229	int s;
230	struct servtab *sep;
231{
232	int ret;
233	char buffer[BUFSIZE];
234
235	inetd_setproctitle(sep->se_service, s);
236	while (1) {
237		while ((ret = read(s, buffer, sizeof(buffer))) > 0)
238			;
239		if (ret == 0 || errno != EINTR)
240			break;
241	}
242	exit(0);
243}
244
245/* ARGSUSED */
246void
247echo_dg(s, sep)			/* Echo service -- echo data back */
248	int s;
249	struct servtab *sep;
250{
251	char buffer[BUFSIZE];
252	int i, size;
253	struct sockaddr_in sin;
254
255	size = sizeof(sin);
256	if ((i = recvfrom(s, buffer, sizeof(buffer), 0,
257			  (struct sockaddr *)&sin, &size)) < 0)
258		return;
259
260	if (check_loop(&sin, sep))
261		return;
262
263	(void) sendto(s, buffer, i, 0, (struct sockaddr *)&sin,
264		      sizeof(sin));
265}
266
267/* ARGSUSED */
268void
269echo_stream(s, sep)		/* Echo service -- echo data back */
270	int s;
271	struct servtab *sep;
272{
273	char buffer[BUFSIZE];
274	int i;
275
276	inetd_setproctitle(sep->se_service, s);
277	while ((i = read(s, buffer, sizeof(buffer))) > 0 &&
278	    write(s, buffer, i) > 0)
279		;
280	exit(0);
281}
282
283/* ARGSUSED */
284void
285iderror(lport, fport, s, er)
286	int lport, fport, s, er;
287{
288	char *p;
289
290	asprintf(&p, "%d , %d : ERROR : %s\r\n", lport, fport,
291	    er == -1 ? "HIDDEN-USER" : er ? strerror(er) : "UNKNOWN-ERROR");
292	if (p == NULL) {
293		syslog(LOG_ERR, "asprintf: %s", strerror(errno));
294		exit(EX_OSERR);
295	}
296	write(s, p, strlen(p));
297	free(p);
298
299	exit(0);
300}
301
302/* ARGSUSED */
303void
304ident_stream(s, sep)		/* Ident service */
305	int s;
306	struct servtab *sep;
307{
308	struct sockaddr_in sin[2];
309	struct ucred uc;
310	struct passwd *pw;
311	struct timeval tv = {
312		10,
313		0
314	};
315	fd_set fdset;
316	char buf[BUFSIZE], *cp = NULL, *p, **av, *osname = NULL;
317	int len, c, rflag = 0, fflag = 0, argc = 0;
318	u_short lport, fport;
319
320	inetd_setproctitle(sep->se_service, s);
321	optind = 1;
322	optreset = 1;
323	for (av = sep->se_argv; *av; av++)
324		argc++;
325	if (argc) {
326		while ((c = getopt(argc, sep->se_argv, "fro:t:")) != -1)
327			switch (c) {
328			case 'f':
329				fflag = 1;
330				break;
331			case 'r':
332				rflag = 1;
333				break;
334			case 'o':
335				osname = optarg;
336				break;
337			case 't': {
338				int sec, usec;
339
340				switch (sscanf(optarg, "%d.%d", &sec, &usec)) {
341				case 2:
342					tv.tv_usec = usec;
343				case 1:
344					tv.tv_sec = sec;
345					break;
346				default:
347					if (debug)
348						warnx("bad -t argument");
349					break;
350				}
351			}
352			default:
353				break;
354			}
355	}
356	if (osname == NULL) {
357		struct utsname un;
358
359		if (uname(&un) == -1)
360			iderror(0, 0, s, errno);
361		osname = un.sysname;
362	}
363	len = sizeof(sin[0]);
364	if (getsockname(s, (struct sockaddr *)&sin[0], &len) == -1)
365		iderror(0, 0, s, errno);
366	len = sizeof(sin[1]);
367	if (getpeername(s, (struct sockaddr *)&sin[1], &len) == -1)
368		iderror(0, 0, s, errno);
369	FD_ZERO(&fdset);
370	FD_SET(s, &fdset);
371	if (select(s + 1, &fdset, NULL, NULL, &tv) == -1)
372		iderror(0, 0, s, errno);
373	if (ioctl(s, FIONREAD, &len) == -1)
374		iderror(0, 0, s, errno);
375	if (len >= sizeof(buf))
376		len = sizeof(buf) - 1;
377	len = read(s, buf, len);
378	if (len == -1)
379		iderror(0, 0, s, errno);
380	buf[len] = '\0';
381	if (sscanf(buf, "%hu , %hu", &lport, &fport) != 2)
382		iderror(0, 0, s, 0);
383	if (!rflag)
384		iderror(lport, fport, s, -1);
385	sin[0].sin_port = htons(lport);
386	sin[1].sin_port = htons(fport);
387	len = sizeof(uc);
388	if (sysctlbyname("net.inet.tcp.getcred", &uc, &len, sin,
389	    sizeof(sin)) == -1)
390		iderror(lport, fport, s, errno);
391	pw = getpwuid(uc.cr_uid);
392	if (pw == NULL)
393		iderror(lport, fport, s, errno);
394	if (fflag) {
395		FILE *fakeid = NULL;
396		char fakeid_path[PATH_MAX];
397		struct stat sb;
398
399		seteuid(pw->pw_uid);
400		setegid(pw->pw_gid);
401		snprintf(fakeid_path, sizeof(fakeid_path), "%s/.fakeid",
402		    pw->pw_dir);
403		if ((fakeid = fopen(fakeid_path, "r")) != NULL &&
404		    fstat(fileno(fakeid), &sb) != -1 && S_ISREG(sb.st_mode)) {
405			buf[sizeof(buf) - 1] = '\0';
406			if (fgets(buf, sizeof(buf), fakeid) == NULL) {
407				cp = pw->pw_name;
408				fclose(fakeid);
409				goto printit;
410			}
411			fclose(fakeid);
412			strtok(buf, "\r\n");
413			if (strlen(buf) > 16)
414				buf[16] = '\0';
415			cp = buf;
416			while (isspace(*cp))
417				cp++;
418			strtok(cp, " \t");
419			if (!*cp || getpwnam(cp))
420				cp = getpwuid(uc.cr_uid)->pw_name;
421		} else
422			cp = pw->pw_name;
423	} else
424		cp = pw->pw_name;
425printit:
426	if (asprintf(&p, "%d , %d : USERID : %s : %s\r\n", lport, fport, osname,
427	    cp) == -1)
428		iderror(0, 0, s, errno);
429	write(s, p, strlen(p));
430	free(p);
431
432	exit(0);
433}
434
435/*
436 * Return a machine readable date and time, in the form of the
437 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
438 * returns the number of seconds since midnight, Jan 1, 1970,
439 * we must add 2208988800 seconds to this figure to make up for
440 * some seventy years Bell Labs was asleep.
441 */
442
443unsigned long
444machtime()
445{
446	struct timeval tv;
447
448	if (gettimeofday(&tv, (struct timezone *)NULL) < 0) {
449		if (debug)
450			warnx("unable to get time of day");
451		return (0L);
452	}
453#define	OFFSET ((u_long)25567 * 24*60*60)
454	return (htonl((long)(tv.tv_sec + OFFSET)));
455#undef OFFSET
456}
457
458/* ARGSUSED */
459void
460machtime_dg(s, sep)
461	int s;
462	struct servtab *sep;
463{
464	unsigned long result;
465	struct sockaddr_in sin;
466	int size;
467
468	size = sizeof(sin);
469	if (recvfrom(s, (char *)&result, sizeof(result), 0,
470		     (struct sockaddr *)&sin, &size) < 0)
471		return;
472
473	if (check_loop(&sin, sep))
474		return;
475
476	result = machtime();
477	(void) sendto(s, (char *) &result, sizeof(result), 0,
478		      (struct sockaddr *)&sin, sizeof(sin));
479}
480
481/* ARGSUSED */
482void
483machtime_stream(s, sep)
484	int s;
485	struct servtab *sep;
486{
487	unsigned long result;
488
489	result = machtime();
490	(void) write(s, (char *) &result, sizeof(result));
491}
492
493/*
494 *  Based on TCPMUX.C by Mark K. Lottor November 1988
495 *  sri-nic::ps:<mkl>tcpmux.c
496 */
497
498#define MAX_SERV_LEN	(256+2)		/* 2 bytes for \r\n */
499#define strwrite(fd, buf)	(void) write(fd, buf, sizeof(buf)-1)
500
501static int		/* # of characters upto \r,\n or \0 */
502getline(fd, buf, len)
503	int fd;
504	char *buf;
505	int len;
506{
507	int count = 0, n;
508	struct sigaction sa;
509
510	sa.sa_flags = 0;
511	sigemptyset(&sa.sa_mask);
512	sa.sa_handler = SIG_DFL;
513	sigaction(SIGALRM, &sa, (struct sigaction *)0);
514	do {
515		alarm(10);
516		n = read(fd, buf, len-count);
517		alarm(0);
518		if (n == 0)
519			return (count);
520		if (n < 0)
521			return (-1);
522		while (--n >= 0) {
523			if (*buf == '\r' || *buf == '\n' || *buf == '\0')
524				return (count);
525			count++;
526			buf++;
527		}
528	} while (count < len);
529	return (count);
530}
531
532struct servtab *
533tcpmux(s)
534	int s;
535{
536	struct servtab *sep;
537	char service[MAX_SERV_LEN+1];
538	int len;
539
540	/* Get requested service name */
541	if ((len = getline(s, service, MAX_SERV_LEN)) < 0) {
542		strwrite(s, "-Error reading service name\r\n");
543		return (NULL);
544	}
545	service[len] = '\0';
546
547	if (debug)
548		warnx("tcpmux: someone wants %s", service);
549
550	/*
551	 * Help is a required command, and lists available services,
552	 * one per line.
553	 */
554	if (!strcasecmp(service, "help")) {
555		for (sep = servtab; sep; sep = sep->se_next) {
556			if (!ISMUX(sep))
557				continue;
558			(void)write(s,sep->se_service,strlen(sep->se_service));
559			strwrite(s, "\r\n");
560		}
561		return (NULL);
562	}
563
564	/* Try matching a service in inetd.conf with the request */
565	for (sep = servtab; sep; sep = sep->se_next) {
566		if (!ISMUX(sep))
567			continue;
568		if (!strcasecmp(service, sep->se_service)) {
569			if (ISMUXPLUS(sep)) {
570				strwrite(s, "+Go\r\n");
571			}
572			return (sep);
573		}
574	}
575	strwrite(s, "-Service not available\r\n");
576	return (NULL);
577}
578
579