xref: /csrg-svn/libexec/ftpd/ftpd.c (revision 26044)
1 /*
2  * Copyright (c) 1985 Regents of the University of California.
3  * All rights reserved.  The Berkeley software License Agreement
4  * specifies the terms and conditions for redistribution.
5  */
6 
7 #ifndef lint
8 char copyright[] =
9 "@(#) Copyright (c) 1985 Regents of the University of California.\n\
10  All rights reserved.\n";
11 #endif not lint
12 
13 #ifndef lint
14 static char sccsid[] = "@(#)ftpd.c	5.2 (Berkeley) 02/03/86";
15 #endif not lint
16 
17 /*
18  * FTP server.
19  */
20 #include <sys/param.h>
21 #include <sys/stat.h>
22 #include <sys/ioctl.h>
23 #include <sys/socket.h>
24 #include <sys/file.h>
25 #include <sys/wait.h>
26 
27 #include <netinet/in.h>
28 
29 #include <arpa/ftp.h>
30 #include <arpa/inet.h>
31 #include <arpa/telnet.h>
32 
33 #include <stdio.h>
34 #include <signal.h>
35 #include <pwd.h>
36 #include <setjmp.h>
37 #include <netdb.h>
38 #include <errno.h>
39 #include <strings.h>
40 
41 /*
42  * File containing login names
43  * NOT to be used on this machine.
44  * Commonly used to disallow uucp.
45  */
46 #define	FTPUSERS	"/etc/ftpusers"
47 
48 extern	int errno;
49 extern	char *sys_errlist[];
50 extern	char *crypt();
51 extern	char version[];
52 extern	char *home;		/* pointer to home directory for glob */
53 extern	FILE *popen(), *fopen(), *freopen();
54 extern	int pclose(), fclose();
55 extern	char *getline();
56 extern	char cbuf[];
57 
58 struct	sockaddr_in ctrl_addr;
59 struct	sockaddr_in data_source;
60 struct	sockaddr_in data_dest;
61 struct	sockaddr_in his_addr;
62 
63 struct	hostent *hp;
64 
65 int	data;
66 jmp_buf	errcatch, urgcatch;
67 int	logged_in;
68 struct	passwd *pw;
69 int	debug;
70 int	timeout;
71 int	logging;
72 int	guest;
73 int	wtmp;
74 int	type;
75 int	form;
76 int	stru;			/* avoid C keyword */
77 int	mode;
78 int	usedefault = 1;		/* for data transfers */
79 int	pdata;			/* for passive mode */
80 int	unique;
81 int	transflag;
82 char	tmpline[7];
83 char	hostname[32];
84 char	remotehost[32];
85 
86 /*
87  * Timeout intervals for retrying connections
88  * to hosts that don't accept PORT cmds.  This
89  * is a kludge, but given the problems with TCP...
90  */
91 #define	SWAITMAX	90	/* wait at most 90 seconds */
92 #define	SWAITINT	5	/* interval between retries */
93 
94 int	swaitmax = SWAITMAX;
95 int	swaitint = SWAITINT;
96 
97 int	lostconn();
98 int	reapchild();
99 int	myoob();
100 FILE	*getdatasock(), *dataconn();
101 
102 main(argc, argv)
103 	int argc;
104 	char *argv[];
105 {
106 	int options = 0, addrlen;
107 	long pgid;
108 	char *cp;
109 
110 	addrlen = sizeof (his_addr);
111 	if (getpeername(0, &his_addr, &addrlen) < 0) {
112 		fprintf(stderr, "%s: ", argv[0]);
113 		perror("getpeername");
114 		exit(1);
115 	}
116 	addrlen = sizeof (ctrl_addr);
117 	if (getsockname(0, &ctrl_addr, &addrlen) < 0) {
118 		fprintf(stderr, "%s: ", argv[0]);
119 		perror("getsockname");
120 		exit(1);
121 	}
122 	data_source.sin_port = htons(ntohs(ctrl_addr.sin_port) - 1);
123 	debug = 0;
124 	argc--, argv++;
125 	while (argc > 0 && *argv[0] == '-') {
126 		for (cp = &argv[0][1]; *cp; cp++) switch (*cp) {
127 
128 		case 'v':
129 			debug = 1;
130 			break;
131 
132 		case 'd':
133 			debug = 1;
134 			options |= SO_DEBUG;
135 			break;
136 
137 		case 'l':
138 			logging = 1;
139 			(void) freopen("/tmp/ftplog", "a", stderr);
140 			break;
141 
142 		case 't':
143 			timeout = atoi(++cp);
144 			goto nextopt;
145 			break;
146 
147 		default:
148 			fprintf(stderr, "ftpd: Unknown flag -%c ignored.\n",
149 			     *cp);
150 			break;
151 		}
152 nextopt:
153 		argc--, argv++;
154 	}
155 	signal(SIGPIPE, lostconn);
156 	signal(SIGCHLD, SIG_IGN);
157 	if (signal(SIGURG, myoob) < 0) {
158 		perror("signal");
159 	}
160 	pgid = getpid();
161 	if (ioctl(fileno(stdin), SIOCSPGRP, (char *) &pgid) < 0) {
162 		perror("ioctl");
163 	}
164 	dolog(&his_addr);
165 	/* do telnet option negotiation here */
166 	/*
167 	 * Set up default state
168 	 */
169 	logged_in = 0;
170 	data = -1;
171 	type = TYPE_A;
172 	form = FORM_N;
173 	stru = STRU_F;
174 	mode = MODE_S;
175 	tmpline[0] = '\0';
176 	gethostname(hostname, sizeof (hostname));
177 	reply(220, "%s FTP server (%s) ready.",
178 		hostname, version);
179 	for (;;) {
180 		setjmp(errcatch);
181 		yyparse();
182 	}
183 }
184 
185 reapchild()
186 {
187 	union wait status;
188 
189 	while (wait3(&status, WNOHANG, 0) > 0)
190 		;
191 }
192 
193 lostconn()
194 {
195 
196 	if (debug)
197 		fprintf(stderr, "Lost connection.\n");
198 	dologout(-1);
199 }
200 
201 pass(passwd)
202 	char *passwd;
203 {
204 	char *xpasswd, *savestr();
205 	static struct passwd save;
206 
207 	if (logged_in || pw == NULL) {
208 		reply(503, "Login with USER first.");
209 		return;
210 	}
211 	if (!guest) {		/* "ftp" is only account allowed no password */
212 		xpasswd = crypt(passwd, pw->pw_passwd);
213 		/* The strcmp does not catch null passwords! */
214 		if (*pw->pw_passwd == '\0' || strcmp(xpasswd, pw->pw_passwd)) {
215 			reply(530, "Login incorrect.");
216 			pw = NULL;
217 			return;
218 		}
219 	}
220 	setegid(pw->pw_gid);
221 	initgroups(pw->pw_name, pw->pw_gid);
222 	if (chdir(pw->pw_dir)) {
223 		reply(550, "User %s: can't change directory to %s.",
224 			pw->pw_name, pw->pw_dir);
225 		goto bad;
226 	}
227 
228 	/* grab wtmp before chroot */
229 	wtmp = open("/usr/adm/wtmp", O_WRONLY|O_APPEND);
230 	if (guest && chroot(pw->pw_dir) < 0) {
231 		reply(550, "Can't set guest privileges.");
232 		if (wtmp >= 0) {
233 			(void) close(wtmp);
234 			wtmp = -1;
235 		}
236 		goto bad;
237 	}
238 	if (!guest)
239 		reply(230, "User %s logged in.", pw->pw_name);
240 	else
241 		reply(230, "Guest login ok, access restrictions apply.");
242 	logged_in = 1;
243 	dologin(pw);
244 	seteuid(pw->pw_uid);
245 	/*
246 	 * Save everything so globbing doesn't
247 	 * clobber the fields.
248 	 */
249 	save = *pw;
250 	save.pw_name = savestr(pw->pw_name);
251 	save.pw_passwd = savestr(pw->pw_passwd);
252 	save.pw_comment = savestr(pw->pw_comment);
253 	save.pw_gecos = savestr(pw->pw_gecos, &save.pw_gecos);
254 	save.pw_dir = savestr(pw->pw_dir);
255 	save.pw_shell = savestr(pw->pw_shell);
256 	pw = &save;
257 	home = pw->pw_dir;		/* home dir for globbing */
258 	return;
259 bad:
260 	seteuid(0);
261 	pw = NULL;
262 }
263 
264 char *
265 savestr(s)
266 	char *s;
267 {
268 	char *malloc();
269 	char *new = malloc(strlen(s) + 1);
270 
271 	if (new != NULL)
272 		strcpy(new, s);
273 	return (new);
274 }
275 
276 retrieve(cmd, name)
277 	char *cmd, *name;
278 {
279 	FILE *fin, *dout;
280 	struct stat st;
281 	int (*closefunc)(), tmp;
282 
283 	if (cmd == 0) {
284 #ifdef notdef
285 		/* no remote command execution -- it's a security hole */
286 		if (*name == '|')
287 			fin = popen(name + 1, "r"), closefunc = pclose;
288 		else
289 #endif
290 			fin = fopen(name, "r"), closefunc = fclose;
291 	} else {
292 		char line[BUFSIZ];
293 
294 		sprintf(line, cmd, name), name = line;
295 		fin = popen(line, "r"), closefunc = pclose;
296 	}
297 	if (fin == NULL) {
298 		if (errno != 0)
299 			reply(550, "%s: %s.", name, sys_errlist[errno]);
300 		return;
301 	}
302 	st.st_size = 0;
303 	if (cmd == 0 &&
304 	    (stat(name, &st) < 0 || (st.st_mode&S_IFMT) != S_IFREG)) {
305 		reply(550, "%s: not a plain file.", name);
306 		goto done;
307 	}
308 	dout = dataconn(name, st.st_size, "w");
309 	if (dout == NULL)
310 		goto done;
311 	if ((tmp = send_data(fin, dout)) > 0 || ferror(dout) > 0) {
312 		reply(550, "%s: %s.", name, sys_errlist[errno]);
313 	}
314 	else if (tmp == 0) {
315 		reply(226, "Transfer complete.");
316 	}
317 	fclose(dout);
318 	data = -1;
319 	pdata = -1;
320 done:
321 	(*closefunc)(fin);
322 }
323 
324 store(name, mode)
325 	char *name, *mode;
326 {
327 	FILE *fout, *din;
328 	int (*closefunc)(), dochown = 0, tmp;
329 	char *gunique(), *local;
330 
331 #ifdef notdef
332 	/* no remote command execution -- it's a security hole */
333 	if (name[0] == '|')
334 		fout = popen(&name[1], "w"), closefunc = pclose;
335 	else
336 #endif
337 	{
338 		struct stat st;
339 
340 		local = name;
341 		if (stat(name, &st) < 0) {
342 			dochown++;
343 		}
344 		else if (unique) {
345 			if ((local = gunique(name)) == NULL) {
346 				return;
347 			}
348 			dochown++;
349 		}
350 		fout = fopen(local, mode), closefunc = fclose;
351 	}
352 	if (fout == NULL) {
353 		reply(550, "%s: %s.", local, sys_errlist[errno]);
354 		return;
355 	}
356 	din = dataconn(local, (off_t)-1, "r");
357 	if (din == NULL)
358 		goto done;
359 	if ((tmp = receive_data(din, fout)) > 0 || ferror(fout) > 0) {
360 		reply(550, "%s: %s.", local, sys_errlist[errno]);
361 	}
362 	else if (tmp == 0 && !unique) {
363 		reply(226, "Transfer complete.");
364 	}
365 	else if (tmp == 0 && unique) {
366 		reply(226, "Transfer complete (unique file name:%s).", local);
367 	}
368 	fclose(din);
369 	data = -1;
370 	pdata = -1;
371 done:
372 	if (dochown)
373 		(void) chown(local, pw->pw_uid, -1);
374 	(*closefunc)(fout);
375 }
376 
377 FILE *
378 getdatasock(mode)
379 	char *mode;
380 {
381 	int s, on = 1;
382 
383 	if (data >= 0)
384 		return (fdopen(data, mode));
385 	s = socket(AF_INET, SOCK_STREAM, 0);
386 	if (s < 0)
387 		return (NULL);
388 	seteuid(0);
389 	if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof (on)) < 0)
390 		goto bad;
391 	/* anchor socket to avoid multi-homing problems */
392 	data_source.sin_family = AF_INET;
393 	data_source.sin_addr = ctrl_addr.sin_addr;
394 	if (bind(s, &data_source, sizeof (data_source), 0) < 0)
395 		goto bad;
396 	seteuid(pw->pw_uid);
397 	return (fdopen(s, mode));
398 bad:
399 	seteuid(pw->pw_uid);
400 	close(s);
401 	return (NULL);
402 }
403 
404 FILE *
405 dataconn(name, size, mode)
406 	char *name;
407 	off_t size;
408 	char *mode;
409 {
410 	char sizebuf[32];
411 	FILE *file;
412 	int retry = 0;
413 
414 	if (size >= 0)
415 		sprintf (sizebuf, " (%ld bytes)", size);
416 	else
417 		(void) strcpy(sizebuf, "");
418 	if (pdata > 0) {
419 		struct sockaddr_in from;
420 		int s, fromlen = sizeof(from);
421 
422 		s = accept(pdata, &from, &fromlen, 0);
423 		if (s < 0) {
424 			reply(425, "Can't open data connection.");
425 			(void) close(pdata);
426 			pdata = -1;
427 			return(NULL);
428 		}
429 		(void) close(pdata);
430 		pdata = s;
431 		reply(150, "Openning data connection for %s (%s,%d)%s.",
432 		     name, inet_ntoa(from.sin_addr.s_addr),
433 		     ntohs(from.sin_port), sizebuf);
434 		return(fdopen(pdata, mode));
435 	}
436 	if (data >= 0) {
437 		reply(125, "Using existing data connection for %s%s.",
438 		    name, sizebuf);
439 		usedefault = 1;
440 		return (fdopen(data, mode));
441 	}
442 	if (usedefault)
443 		data_dest = his_addr;
444 	usedefault = 1;
445 	file = getdatasock(mode);
446 	if (file == NULL) {
447 		reply(425, "Can't create data socket (%s,%d): %s.",
448 		    inet_ntoa(data_source.sin_addr),
449 		    ntohs(data_source.sin_port),
450 		    sys_errlist[errno]);
451 		return (NULL);
452 	}
453 	reply(150, "Opening data connection for %s (%s,%d)%s.",
454 	    name, inet_ntoa(data_dest.sin_addr.s_addr),
455 	    ntohs(data_dest.sin_port), sizebuf);
456 	data = fileno(file);
457 	while (connect(data, &data_dest, sizeof (data_dest)) < 0) {
458 		if (errno == EADDRINUSE && retry < swaitmax) {
459 			sleep(swaitint);
460 			retry += swaitint;
461 			continue;
462 		}
463 		reply(425, "Can't build data connection: %s.",
464 		    sys_errlist[errno]);
465 		(void) fclose(file);
466 		data = -1;
467 		return (NULL);
468 	}
469 	return (file);
470 }
471 
472 /*
473  * Tranfer the contents of "instr" to
474  * "outstr" peer using the appropriate
475  * encapulation of the date subject
476  * to Mode, Structure, and Type.
477  *
478  * NB: Form isn't handled.
479  */
480 send_data(instr, outstr)
481 	FILE *instr, *outstr;
482 {
483 	register int c;
484 	int netfd, filefd, cnt;
485 	char buf[BUFSIZ];
486 
487 	transflag++;
488 	if (setjmp(urgcatch)) {
489 		transflag = 0;
490 		return(-1);
491 	}
492 	switch (type) {
493 
494 	case TYPE_A:
495 		while ((c = getc(instr)) != EOF) {
496 			if (c == '\n') {
497 				if (ferror (outstr)) {
498 					transflag = 0;
499 					return (1);
500 				}
501 				putc('\r', outstr);
502 			}
503 			putc(c, outstr);
504 		/*	if (c == '\r')			*/
505 		/*		putc ('\0', outstr);	*/
506 		}
507 		transflag = 0;
508 		if (ferror (instr) || ferror (outstr)) {
509 			return (1);
510 		}
511 		return (0);
512 
513 	case TYPE_I:
514 	case TYPE_L:
515 		netfd = fileno(outstr);
516 		filefd = fileno(instr);
517 
518 		while ((cnt = read(filefd, buf, sizeof (buf))) > 0) {
519 			if (write(netfd, buf, cnt) < 0) {
520 				transflag = 0;
521 				return (1);
522 			}
523 		}
524 		transflag = 0;
525 		return (cnt < 0);
526 	}
527 	reply(504,"Unimplemented TYPE %d in send_data", type);
528 	transflag = 0;
529 	return (1);
530 }
531 
532 /*
533  * Transfer data from peer to
534  * "outstr" using the appropriate
535  * encapulation of the data subject
536  * to Mode, Structure, and Type.
537  *
538  * N.B.: Form isn't handled.
539  */
540 receive_data(instr, outstr)
541 	FILE *instr, *outstr;
542 {
543 	register int c;
544 	int cnt;
545 	char buf[BUFSIZ];
546 
547 
548 	transflag++;
549 	if (setjmp(urgcatch)) {
550 		transflag = 0;
551 		return(-1);
552 	}
553 	switch (type) {
554 
555 	case TYPE_I:
556 	case TYPE_L:
557 		while ((cnt = read(fileno(instr), buf, sizeof buf)) > 0) {
558 			if (write(fileno(outstr), buf, cnt) < 0) {
559 				transflag = 0;
560 				return (1);
561 			}
562 		}
563 		transflag = 0;
564 		return (cnt < 0);
565 
566 	case TYPE_E:
567 		reply(504, "TYPE E not implemented.");
568 		transflag = 0;
569 		return (1);
570 
571 	case TYPE_A:
572 		while ((c = getc(instr)) != EOF) {
573 			if (c == '\r') {
574 				if (ferror (outstr)) {
575 					transflag = 0;
576 					return (1);
577 				}
578 				if ((c = getc(instr)) != '\n')
579 					putc ('\r', outstr);
580 			/*	if (c == '\0')			*/
581 			/*		continue;		*/
582 			}
583 			putc (c, outstr);
584 		}
585 		transflag = 0;
586 		if (ferror (instr) || ferror (outstr))
587 			return (1);
588 		return (0);
589 	}
590 	transflag = 0;
591 	fatal("Unknown type in receive_data.");
592 	/*NOTREACHED*/
593 }
594 
595 fatal(s)
596 	char *s;
597 {
598 	reply(451, "Error in server: %s\n", s);
599 	reply(221, "Closing connection due to server error.");
600 	dologout(0);
601 }
602 
603 reply(n, s, args)
604 	int n;
605 	char *s;
606 {
607 
608 	printf("%d ", n);
609 	_doprnt(s, &args, stdout);
610 	printf("\r\n");
611 	fflush(stdout);
612 	if (debug) {
613 		fprintf(stderr, "<--- %d ", n);
614 		_doprnt(s, &args, stderr);
615 		fprintf(stderr, "\n");
616 		fflush(stderr);
617 	}
618 }
619 
620 lreply(n, s, args)
621 	int n;
622 	char *s;
623 {
624 	printf("%d-", n);
625 	_doprnt(s, &args, stdout);
626 	printf("\r\n");
627 	fflush(stdout);
628 	if (debug) {
629 		fprintf(stderr, "<--- %d-", n);
630 		_doprnt(s, &args, stderr);
631 		fprintf(stderr, "\n");
632 	}
633 }
634 
635 replystr(s)
636 	char *s;
637 {
638 	printf("%s\r\n", s);
639 	fflush(stdout);
640 	if (debug)
641 		fprintf(stderr, "<--- %s\n", s);
642 }
643 
644 ack(s)
645 	char *s;
646 {
647 	reply(200, "%s command successful.", s);
648 }
649 
650 nack(s)
651 	char *s;
652 {
653 	reply(502, "%s command not implemented.", s);
654 }
655 
656 yyerror()
657 {
658 	char *cp;
659 
660 	cp = index(cbuf,'\n');
661 	*cp = '\0';
662 	reply(500, "'%s': command not understood.",cbuf);
663 }
664 
665 delete(name)
666 	char *name;
667 {
668 	struct stat st;
669 
670 	if (stat(name, &st) < 0) {
671 		reply(550, "%s: %s.", name, sys_errlist[errno]);
672 		return;
673 	}
674 	if ((st.st_mode&S_IFMT) == S_IFDIR) {
675 		if (rmdir(name) < 0) {
676 			reply(550, "%s: %s.", name, sys_errlist[errno]);
677 			return;
678 		}
679 		goto done;
680 	}
681 	if (unlink(name) < 0) {
682 		reply(550, "%s: %s.", name, sys_errlist[errno]);
683 		return;
684 	}
685 done:
686 	ack("DELE");
687 }
688 
689 cwd(path)
690 	char *path;
691 {
692 
693 	if (chdir(path) < 0) {
694 		reply(550, "%s: %s.", path, sys_errlist[errno]);
695 		return;
696 	}
697 	ack("CWD");
698 }
699 
700 makedir(name)
701 	char *name;
702 {
703 	struct stat st;
704 	int dochown = stat(name, &st) < 0;
705 
706 	if (mkdir(name, 0777) < 0) {
707 		reply(550, "%s: %s.", name, sys_errlist[errno]);
708 		return;
709 	}
710 	if (dochown)
711 		(void) chown(name, pw->pw_uid, -1);
712 	ack("MKDIR");
713 }
714 
715 removedir(name)
716 	char *name;
717 {
718 
719 	if (rmdir(name) < 0) {
720 		reply(550, "%s: %s.", name, sys_errlist[errno]);
721 		return;
722 	}
723 	ack("RMDIR");
724 }
725 
726 pwd()
727 {
728 	char path[MAXPATHLEN + 1];
729 
730 	if (getwd(path) == NULL) {
731 		reply(451, "%s.", path);
732 		return;
733 	}
734 	reply(251, "\"%s\" is current directory.", path);
735 }
736 
737 char *
738 renamefrom(name)
739 	char *name;
740 {
741 	struct stat st;
742 
743 	if (stat(name, &st) < 0) {
744 		reply(550, "%s: %s.", name, sys_errlist[errno]);
745 		return ((char *)0);
746 	}
747 	reply(350, "File exists, ready for destination name");
748 	return (name);
749 }
750 
751 renamecmd(from, to)
752 	char *from, *to;
753 {
754 
755 	if (rename(from, to) < 0) {
756 		reply(550, "rename: %s.", sys_errlist[errno]);
757 		return;
758 	}
759 	ack("RNTO");
760 }
761 
762 dolog(sin)
763 	struct sockaddr_in *sin;
764 {
765 	struct hostent *hp = gethostbyaddr(&sin->sin_addr,
766 		sizeof (struct in_addr), AF_INET);
767 	time_t t;
768 
769 	if (hp) {
770 		strncpy(remotehost, hp->h_name, sizeof (remotehost));
771 		endhostent();
772 	} else
773 		strncpy(remotehost, inet_ntoa(sin->sin_addr),
774 		    sizeof (remotehost));
775 	if (!logging)
776 		return;
777 	t = time(0);
778 	fprintf(stderr,"FTPD: connection from %s at %s", remotehost, ctime(&t));
779 	fflush(stderr);
780 }
781 
782 #include <utmp.h>
783 
784 #define	SCPYN(a, b)	strncpy(a, b, sizeof (a))
785 struct	utmp utmp;
786 
787 /*
788  * Record login in wtmp file.
789  */
790 dologin(pw)
791 	struct passwd *pw;
792 {
793 	char line[32];
794 
795 	if (wtmp >= 0) {
796 		/* hack, but must be unique and no tty line */
797 		sprintf(line, "ftp%d", getpid());
798 		SCPYN(utmp.ut_line, line);
799 		SCPYN(utmp.ut_name, pw->pw_name);
800 		SCPYN(utmp.ut_host, remotehost);
801 		utmp.ut_time = time(0);
802 		(void) write(wtmp, (char *)&utmp, sizeof (utmp));
803 		if (!guest) {		/* anon must hang on */
804 			(void) close(wtmp);
805 			wtmp = -1;
806 		}
807 	}
808 }
809 
810 /*
811  * Record logout in wtmp file
812  * and exit with supplied status.
813  */
814 dologout(status)
815 	int status;
816 {
817 
818 	if (logged_in) {
819 		(void) seteuid(0);
820 		if (wtmp < 0)
821 			wtmp = open("/usr/adm/wtmp", O_WRONLY|O_APPEND);
822 		if (wtmp >= 0) {
823 			SCPYN(utmp.ut_name, "");
824 			SCPYN(utmp.ut_host, "");
825 			utmp.ut_time = time(0);
826 			(void) write(wtmp, (char *)&utmp, sizeof (utmp));
827 			(void) close(wtmp);
828 		}
829 	}
830 	/* beware of flushing buffers after a SIGPIPE */
831 	_exit(status);
832 }
833 
834 /*
835  * Special version of popen which avoids
836  * call to shell.  This insures noone may
837  * create a pipe to a hidden program as a side
838  * effect of a list or dir command.
839  */
840 #define	tst(a,b)	(*mode == 'r'? (b) : (a))
841 #define	RDR	0
842 #define	WTR	1
843 static	int popen_pid[5];
844 
845 static char *
846 nextarg(cpp)
847 	char *cpp;
848 {
849 	register char *cp = cpp;
850 
851 	if (cp == 0)
852 		return (cp);
853 	while (*cp && *cp != ' ' && *cp != '\t')
854 		cp++;
855 	if (*cp == ' ' || *cp == '\t') {
856 		*cp++ = '\0';
857 		while (*cp == ' ' || *cp == '\t')
858 			cp++;
859 	}
860 	if (cp == cpp)
861 		return ((char *)0);
862 	return (cp);
863 }
864 
865 FILE *
866 popen(cmd, mode)
867 	char *cmd, *mode;
868 {
869 	int p[2], ac, gac;
870 	register myside, hisside, pid;
871 	char *av[20], *gav[512];
872 	register char *cp;
873 
874 	if (pipe(p) < 0)
875 		return (NULL);
876 	cp = cmd, ac = 0;
877 	/* break up string into pieces */
878 	do {
879 		av[ac++] = cp;
880 		cp = nextarg(cp);
881 	} while (cp && *cp && ac < 20);
882 	av[ac] = (char *)0;
883 	gav[0] = av[0];
884 	/* glob each piece */
885 	for (gac = ac = 1; av[ac] != NULL; ac++) {
886 		char **pop;
887 		extern char **glob(), **copyblk();
888 
889 		pop = glob(av[ac]);
890 		if (pop == (char **)NULL) {	/* globbing failed */
891 			char *vv[2];
892 
893 			vv[0] = av[ac];
894 			vv[1] = 0;
895 			pop = copyblk(vv);
896 		}
897 		av[ac] = (char *)pop;		/* save to free later */
898 		while (*pop && gac < 512)
899 			gav[gac++] = *pop++;
900 	}
901 	gav[gac] = (char *)0;
902 	myside = tst(p[WTR], p[RDR]);
903 	hisside = tst(p[RDR], p[WTR]);
904 	if ((pid = fork()) == 0) {
905 		/* myside and hisside reverse roles in child */
906 		close(myside);
907 		dup2(hisside, tst(0, 1));
908 		close(hisside);
909 		execv(gav[0], gav);
910 		_exit(1);
911 	}
912 	for (ac = 1; av[ac] != NULL; ac++)
913 		blkfree((char **)av[ac]);
914 	if (pid == -1)
915 		return (NULL);
916 	popen_pid[myside] = pid;
917 	close(hisside);
918 	return (fdopen(myside, mode));
919 }
920 
921 pclose(ptr)
922 	FILE *ptr;
923 {
924 	register f, r, (*hstat)(), (*istat)(), (*qstat)();
925 	int status;
926 
927 	f = fileno(ptr);
928 	fclose(ptr);
929 	istat = signal(SIGINT, SIG_IGN);
930 	qstat = signal(SIGQUIT, SIG_IGN);
931 	hstat = signal(SIGHUP, SIG_IGN);
932 	while ((r = wait(&status)) != popen_pid[f] && r != -1)
933 		;
934 	if (r == -1)
935 		status = -1;
936 	signal(SIGINT, istat);
937 	signal(SIGQUIT, qstat);
938 	signal(SIGHUP, hstat);
939 	return (status);
940 }
941 
942 /*
943  * Check user requesting login priviledges.
944  * Disallow anyone mentioned in the file FTPUSERS
945  * to allow people such as uucp to be avoided.
946  */
947 checkuser(name)
948 	register char *name;
949 {
950 	char line[BUFSIZ], *index();
951 	FILE *fd;
952 	int found = 0;
953 
954 	fd = fopen(FTPUSERS, "r");
955 	if (fd == NULL)
956 		return (1);
957 	while (fgets(line, sizeof (line), fd) != NULL) {
958 		register char *cp = index(line, '\n');
959 
960 		if (cp)
961 			*cp = '\0';
962 		if (strcmp(line, name) == 0) {
963 			found++;
964 			break;
965 		}
966 	}
967 	fclose(fd);
968 	return (!found);
969 }
970 
971 myoob()
972 {
973 	char mark, *cp;
974 	int aflag = 0, count = 0, iacflag = 0, c;
975 
976 	if (!transflag) {
977 		for (;;) {
978 			if (ioctl(fileno(stdin), SIOCATMARK, &mark) < 0) {
979 				perror("ioctl");
980 				break;
981 			}
982 			if (mark) {
983 				break;
984 			}
985 			read(fileno(stdin), &mark, 1);
986 			c = 0377 & mark;
987 		}
988 		recv(fileno(stdin), &mark, 1, MSG_OOB);
989 		c = 0377 & mark;
990 		read(fileno(stdin), &mark, 1);
991 		return;
992 	}
993 	for (;;) {
994 		if (ioctl(fileno(stdin), SIOCATMARK, &mark) < 0) {
995 			perror("ioctl");
996 			break;
997 		}
998 		if (mark) {
999 			break;
1000 		}
1001 		read(fileno(stdin), &mark, 1);
1002 		c = 0377 & mark;
1003 		if (c == IAC) {
1004 			aflag++;
1005 		}
1006 		else if (c == IP) {
1007 			aflag++;
1008 		}
1009 	}
1010 	recv(fileno(stdin), &mark, 1, MSG_OOB);
1011 	c = 0377 & mark;
1012 	if (c == IAC) {
1013 		aflag++;
1014 	}
1015 	read(fileno(stdin), &mark, 1);
1016 	c = 0377 & mark;
1017 	if (c == DM) {
1018 		aflag++;
1019 	}
1020 	if (aflag != 4) {
1021 		return;
1022 	}
1023 	cp = tmpline;
1024 	(void) getline(cp, 7, stdin);
1025 	upper(cp);
1026 	if (strcmp(cp, "ABOR\r\n")) {
1027 		return;
1028 	}
1029 	tmpline[0] = '\0';
1030 	reply(426,"Transfer aborted. Data connection closed.");
1031 	reply(226,"Abort successful");
1032 	longjmp(urgcatch, 1);
1033 }
1034 
1035 passive()
1036 {
1037 	int len;
1038 	struct sockaddr_in tmp;
1039 	register char *p, *a;
1040 
1041 	pdata = socket(AF_INET, SOCK_STREAM, 0);
1042 	if (pdata < 0) {
1043 		reply(451, "Can't open passive connection");
1044 		return;
1045 	}
1046 	tmp = ctrl_addr;
1047 	tmp.sin_port = 0;
1048 	seteuid(0);
1049 	if (bind(pdata, (char *) &tmp, sizeof(tmp), 0) < 0) {
1050 		seteuid(pw->pw_uid);
1051 		(void) close(pdata);
1052 		pdata = -1;
1053 		reply(451, "Can't open passive connection");
1054 		return;
1055 	}
1056 	seteuid(pw->pw_uid);
1057 	len = sizeof(tmp);
1058 	if (getsockname(pdata, (char *) &tmp, &len) < 0) {
1059 		(void) close(pdata);
1060 		pdata = -1;
1061 		reply(451, "Can't open passive connection");
1062 		return;
1063 	}
1064 	if (listen(pdata, 1) < 0) {
1065 		(void) close(pdata);
1066 		pdata = -1;
1067 		reply(451, "Can't open passive connection");
1068 		return;
1069 	}
1070 	a = (char *) &tmp.sin_addr;
1071 	p = (char *) &tmp.sin_port;
1072 
1073 #define UC(b) (((int) b) & 0xff)
1074 
1075 	reply(227, "Entering Passive Mode (%d,%d,%d,%d,%d,%d)", UC(a[0]),
1076 		UC(a[1]), UC(a[2]), UC(a[3]), UC(p[0]), UC(p[1]));
1077 }
1078 
1079 char *
1080 gunique(local)
1081 	char *local;
1082 {
1083 	static char new[MAXPATHLEN];
1084 	char *cp = rindex(local, '/');
1085 	int d, count=0;
1086 	char ext = '1';
1087 
1088 	if (cp) {
1089 		*cp = '\0';
1090 	}
1091 	d = access(cp ? local : ".", 2);
1092 	if (cp) {
1093 		*cp = '/';
1094 	}
1095 	if (d < 0) {
1096 		perror(local);
1097 		return((char *) 0);
1098 	}
1099 	(void) strcpy(new, local);
1100 	cp = new + strlen(new);
1101 	*cp++ = '.';
1102 	while (!d) {
1103 		if (++count == 100) {
1104 			reply(451, "Unique file name not cannot be created.");
1105 			return((char *) 0);
1106 		}
1107 		*cp++ = ext;
1108 		*cp = '\0';
1109 		if (ext == '9') {
1110 			ext = '0';
1111 		}
1112 		else {
1113 			ext++;
1114 		}
1115 		if ((d = access(new, 0)) < 0) {
1116 			break;
1117 		}
1118 		if (ext != '0') {
1119 			cp--;
1120 		}
1121 		else if (*(cp - 2) == '.') {
1122 			*(cp - 1) = '1';
1123 		}
1124 		else {
1125 			*(cp - 2) = *(cp - 2) + 1;
1126 			cp--;
1127 		}
1128 	}
1129 	return(new);
1130 }
1131