builtins.c revision 49030 
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 1.5 1999/07/23 15:00:07 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, "Out of memory.");
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	FILE *fakeid = NULL;
309	struct stat sb;
310	struct utsname un;
311	struct sockaddr_in sin[2];
312	struct ucred uc;
313	struct passwd *pw;
314	struct timeval tv = {
315		10,
316		0
317	};
318	fd_set fdset;
319	char fakeid_path[PATH_MAX];
320	char buf[BUFSIZE], *cp = NULL, *p, **av, *osname = NULL;
321	int sec, usec;
322	int len, c, rflag = 0, fflag = 0, argc = 0;
323	u_short lport, fport;
324
325	inetd_setproctitle(sep->se_service, s);
326	optind = 1;
327	optreset = 1;
328	for (av = sep->se_argv; *av; av++)
329		argc++;
330	if (argc) {
331		while ((c = getopt(argc, sep->se_argv, "fro:t:")) != -1)
332			switch (c) {
333			case 'f':
334				fflag = 1;
335				break;
336			case 'r':
337				rflag = 1;
338				break;
339			case 'o':
340				osname = optarg;
341				break;
342			case 't':
343				switch (sscanf(optarg, "%d.%d", &sec, &usec)) {
344				case 2:
345					tv.tv_usec = usec;
346				case 1:
347					tv.tv_sec = sec;
348					break;
349				default:
350					if (debug)
351						warnx("bad -t argument");
352					break;
353				}
354			default:
355				break;
356			}
357	}
358	if (osname == NULL) {
359		if (uname(&un))
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		seteuid(pw->pw_uid);
396		setegid(pw->pw_gid);
397		snprintf(fakeid_path, sizeof(fakeid_path), "%s/.fakeid",
398		    pw->pw_dir);
399		if ((fakeid = fopen(fakeid_path, "r")) != NULL &&
400		    fstat(fileno(fakeid), &sb) != -1 && S_ISREG(sb.st_mode)) {
401			buf[sizeof(buf) - 1] = '\0';
402			if (fgets(buf, sizeof(buf), fakeid) == NULL) {
403				cp = pw->pw_name;
404				fclose(fakeid);
405				goto printit;
406			}
407			fclose(fakeid);
408			strtok(buf, "\r\n");
409			if (strlen(buf) > 16)
410				buf[16] = '\0';
411			cp = buf;
412			while (isspace(*cp))
413				cp++;
414			strtok(cp, " \t");
415			if (!*cp || getpwnam(cp))
416				cp = getpwuid(uc.cr_uid)->pw_name;
417		} else
418			cp = pw->pw_name;
419	} else
420		cp = pw->pw_name;
421printit:
422	if (asprintf(&p, "%d , %d : USERID : %s : %s\r\n", lport, fport, osname,
423	    cp) == -1)
424		iderror(0, 0, s, errno);
425	write(s, p, strlen(p));
426	free(p);
427
428	exit(0);
429}
430
431/*
432 * Return a machine readable date and time, in the form of the
433 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
434 * returns the number of seconds since midnight, Jan 1, 1970,
435 * we must add 2208988800 seconds to this figure to make up for
436 * some seventy years Bell Labs was asleep.
437 */
438
439unsigned long
440machtime()
441{
442	struct timeval tv;
443
444	if (gettimeofday(&tv, (struct timezone *)NULL) < 0) {
445		if (debug)
446			warnx("unable to get time of day");
447		return (0L);
448	}
449#define	OFFSET ((u_long)25567 * 24*60*60)
450	return (htonl((long)(tv.tv_sec + OFFSET)));
451#undef OFFSET
452}
453
454/* ARGSUSED */
455void
456machtime_dg(s, sep)
457	int s;
458	struct servtab *sep;
459{
460	unsigned long result;
461	struct sockaddr_in sin;
462	int size;
463
464	size = sizeof(sin);
465	if (recvfrom(s, (char *)&result, sizeof(result), 0,
466		     (struct sockaddr *)&sin, &size) < 0)
467		return;
468
469	if (check_loop(&sin, sep))
470		return;
471
472	result = machtime();
473	(void) sendto(s, (char *) &result, sizeof(result), 0,
474		      (struct sockaddr *)&sin, sizeof(sin));
475}
476
477/* ARGSUSED */
478void
479machtime_stream(s, sep)
480	int s;
481	struct servtab *sep;
482{
483	unsigned long result;
484
485	result = machtime();
486	(void) write(s, (char *) &result, sizeof(result));
487}
488
489/*
490 *  Based on TCPMUX.C by Mark K. Lottor November 1988
491 *  sri-nic::ps:<mkl>tcpmux.c
492 */
493
494#define MAX_SERV_LEN	(256+2)		/* 2 bytes for \r\n */
495#define strwrite(fd, buf)	(void) write(fd, buf, sizeof(buf)-1)
496
497static int		/* # of characters upto \r,\n or \0 */
498getline(fd, buf, len)
499	int fd;
500	char *buf;
501	int len;
502{
503	int count = 0, n;
504	struct sigaction sa;
505
506	sa.sa_flags = 0;
507	sigemptyset(&sa.sa_mask);
508	sa.sa_handler = SIG_DFL;
509	sigaction(SIGALRM, &sa, (struct sigaction *)0);
510	do {
511		alarm(10);
512		n = read(fd, buf, len-count);
513		alarm(0);
514		if (n == 0)
515			return (count);
516		if (n < 0)
517			return (-1);
518		while (--n >= 0) {
519			if (*buf == '\r' || *buf == '\n' || *buf == '\0')
520				return (count);
521			count++;
522			buf++;
523		}
524	} while (count < len);
525	return (count);
526}
527
528struct servtab *
529tcpmux(s)
530	int s;
531{
532	struct servtab *sep;
533	char service[MAX_SERV_LEN+1];
534	int len;
535
536	/* Get requested service name */
537	if ((len = getline(s, service, MAX_SERV_LEN)) < 0) {
538		strwrite(s, "-Error reading service name\r\n");
539		return (NULL);
540	}
541	service[len] = '\0';
542
543	if (debug)
544		warnx("tcpmux: someone wants %s", service);
545
546	/*
547	 * Help is a required command, and lists available services,
548	 * one per line.
549	 */
550	if (!strcasecmp(service, "help")) {
551		for (sep = servtab; sep; sep = sep->se_next) {
552			if (!ISMUX(sep))
553				continue;
554			(void)write(s,sep->se_service,strlen(sep->se_service));
555			strwrite(s, "\r\n");
556		}
557		return (NULL);
558	}
559
560	/* Try matching a service in inetd.conf with the request */
561	for (sep = servtab; sep; sep = sep->se_next) {
562		if (!ISMUX(sep))
563			continue;
564		if (!strcasecmp(service, sep->se_service)) {
565			if (ISMUXPLUS(sep)) {
566				strwrite(s, "+Go\r\n");
567			}
568			return (sep);
569		}
570	}
571	strwrite(s, "-Service not available\r\n");
572	return (NULL);
573}
574
575