xref: /freebsd/lib/libfetch/ftp.c (revision 42c159fe388a3765f69860c84183700af37aca8a)
1 /*-
2  * Copyright (c) 1998 Dag-Erling Co�dan Sm�rgrav
3  * 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  *    in this position and unchanged.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. The name of the author may not be used to endorse or promote products
15  *    derived from this software without specific prior written permission
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 /*
33  * Portions of this code were taken from or based on ftpio.c:
34  *
35  * ----------------------------------------------------------------------------
36  * "THE BEER-WARE LICENSE" (Revision 42):
37  * <phk@FreeBSD.org> wrote this file.  As long as you retain this notice you
38  * can do whatever you want with this stuff. If we meet some day, and you think
39  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
40  * ----------------------------------------------------------------------------
41  *
42  * Major Changelog:
43  *
44  * Dag-Erling Co�dan Sm�rgrav
45  * 9 Jun 1998
46  *
47  * Incorporated into libfetch
48  *
49  * Jordan K. Hubbard
50  * 17 Jan 1996
51  *
52  * Turned inside out. Now returns xfers as new file ids, not as a special
53  * `state' of FTP_t
54  *
55  * $ftpioId: ftpio.c,v 1.30 1998/04/11 07:28:53 phk Exp $
56  *
57  */
58 
59 #include <sys/param.h>
60 #include <sys/socket.h>
61 #include <netinet/in.h>
62 
63 #include <ctype.h>
64 #include <err.h>
65 #include <errno.h>
66 #include <fcntl.h>
67 #include <netdb.h>
68 #include <stdarg.h>
69 #include <stdio.h>
70 #include <stdlib.h>
71 #include <string.h>
72 #include <time.h>
73 #include <unistd.h>
74 
75 #include "fetch.h"
76 #include "common.h"
77 #include "ftperr.h"
78 
79 #define FTP_ANONYMOUS_USER	"anonymous"
80 
81 #define FTP_CONNECTION_ALREADY_OPEN	125
82 #define FTP_OPEN_DATA_CONNECTION	150
83 #define FTP_OK				200
84 #define FTP_FILE_STATUS			213
85 #define FTP_SERVICE_READY		220
86 #define FTP_TRANSFER_COMPLETE		226
87 #define FTP_PASSIVE_MODE		227
88 #define FTP_LPASSIVE_MODE		228
89 #define FTP_EPASSIVE_MODE		229
90 #define FTP_LOGGED_IN			230
91 #define FTP_FILE_ACTION_OK		250
92 #define FTP_NEED_PASSWORD		331
93 #define FTP_NEED_ACCOUNT		332
94 #define FTP_FILE_OK			350
95 #define FTP_SYNTAX_ERROR		500
96 #define FTP_PROTOCOL_ERROR		999
97 
98 static struct url cached_host;
99 static int	 cached_socket;
100 
101 static char	*last_reply;
102 static size_t	 lr_size;
103 static size_t	 lr_length;
104 static int	 last_code;
105 
106 #define isftpreply(foo) (isdigit(foo[0]) && isdigit(foo[1]) \
107 			 && isdigit(foo[2]) \
108 			 && (foo[3] == ' ' || foo[3] == '\0'))
109 #define isftpinfo(foo) (isdigit(foo[0]) && isdigit(foo[1]) \
110 			&& isdigit(foo[2]) && foo[3] == '-')
111 
112 /*
113  * Translate IPv4 mapped IPv6 address to IPv4 address
114  */
115 static void
116 unmappedaddr(struct sockaddr_in6 *sin6)
117 {
118 	struct sockaddr_in *sin4;
119 	u_int32_t addr;
120 	int port;
121 
122 	if (sin6->sin6_family != AF_INET6 ||
123 	    !IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
124 		return;
125 	sin4 = (struct sockaddr_in *)sin6;
126 	addr = *(u_int32_t *)&sin6->sin6_addr.s6_addr[12];
127 	port = sin6->sin6_port;
128 	memset(sin4, 0, sizeof(struct sockaddr_in));
129 	sin4->sin_addr.s_addr = addr;
130 	sin4->sin_port = port;
131 	sin4->sin_family = AF_INET;
132 	sin4->sin_len = sizeof(struct sockaddr_in);
133 }
134 
135 /*
136  * Get server response
137  */
138 static int
139 _ftp_chkerr(int cd)
140 {
141 	if (_fetch_getln(cd, &last_reply, &lr_size, &lr_length) == -1) {
142 		_fetch_syserr();
143 		return (-1);
144 	}
145 	if (isftpinfo(last_reply)) {
146 		while (lr_length && !isftpreply(last_reply)) {
147 			if (_fetch_getln(cd, &last_reply,
148 			    &lr_size, &lr_length) == -1) {
149 				_fetch_syserr();
150 				return (-1);
151 			}
152 		}
153 	}
154 
155 	while (lr_length && isspace(last_reply[lr_length-1]))
156 		lr_length--;
157 	last_reply[lr_length] = 0;
158 
159 	if (!isftpreply(last_reply)) {
160 		_ftp_seterr(FTP_PROTOCOL_ERROR);
161 		return (-1);
162 	}
163 
164 	last_code = (last_reply[0] - '0') * 100
165 	    + (last_reply[1] - '0') * 10
166 	    + (last_reply[2] - '0');
167 
168 	return (last_code);
169 }
170 
171 /*
172  * Send a command and check reply
173  */
174 static int
175 _ftp_cmd(int cd, const char *fmt, ...)
176 {
177 	va_list ap;
178 	size_t len;
179 	char *msg;
180 	int r;
181 
182 	va_start(ap, fmt);
183 	len = vasprintf(&msg, fmt, ap);
184 	va_end(ap);
185 
186 	if (msg == NULL) {
187 		errno = ENOMEM;
188 		_fetch_syserr();
189 		return (-1);
190 	}
191 
192 	r = _fetch_putln(cd, msg, len);
193 	free(msg);
194 
195 	if (r == -1) {
196 		_fetch_syserr();
197 		return (-1);
198 	}
199 
200 	return (_ftp_chkerr(cd));
201 }
202 
203 /*
204  * Return a pointer to the filename part of a path
205  */
206 static const char *
207 _ftp_filename(const char *file)
208 {
209 	char *s;
210 
211 	if ((s = strrchr(file, '/')) == NULL)
212 		return (file);
213 	else
214 		return (s + 1);
215 }
216 
217 /*
218  * Change working directory to the directory that contains the specified
219  * file.
220  */
221 static int
222 _ftp_cwd(int cd, const char *file)
223 {
224 	char *s;
225 	int e;
226 
227 	if ((s = strrchr(file, '/')) == NULL || s == file) {
228 		e = _ftp_cmd(cd, "CWD /");
229 	} else {
230 		e = _ftp_cmd(cd, "CWD %.*s", s - file, file);
231 	}
232 	if (e != FTP_FILE_ACTION_OK) {
233 		_ftp_seterr(e);
234 		return (-1);
235 	}
236 	return (0);
237 }
238 
239 /*
240  * Request and parse file stats
241  */
242 static int
243 _ftp_stat(int cd, const char *file, struct url_stat *us)
244 {
245 	char *ln;
246 	const char *s;
247 	struct tm tm;
248 	time_t t;
249 	int e;
250 
251 	us->size = -1;
252 	us->atime = us->mtime = 0;
253 
254 	if ((s = strrchr(file, '/')) == NULL)
255 		s = file;
256 	else
257 		++s;
258 
259 	if ((e = _ftp_cmd(cd, "SIZE %s", s)) != FTP_FILE_STATUS) {
260 		_ftp_seterr(e);
261 		return (-1);
262 	}
263 	for (ln = last_reply + 4; *ln && isspace(*ln); ln++)
264 		/* nothing */ ;
265 	for (us->size = 0; *ln && isdigit(*ln); ln++)
266 		us->size = us->size * 10 + *ln - '0';
267 	if (*ln && !isspace(*ln)) {
268 		_ftp_seterr(FTP_PROTOCOL_ERROR);
269 		us->size = -1;
270 		return (-1);
271 	}
272 	if (us->size == 0)
273 		us->size = -1;
274 	DEBUG(fprintf(stderr, "size: [%lld]\n", (long long)us->size));
275 
276 	if ((e = _ftp_cmd(cd, "MDTM %s", s)) != FTP_FILE_STATUS) {
277 		_ftp_seterr(e);
278 		return (-1);
279 	}
280 	for (ln = last_reply + 4; *ln && isspace(*ln); ln++)
281 		/* nothing */ ;
282 	switch (strspn(ln, "0123456789")) {
283 	case 14:
284 		break;
285 	case 15:
286 		ln++;
287 		ln[0] = '2';
288 		ln[1] = '0';
289 		break;
290 	default:
291 		_ftp_seterr(FTP_PROTOCOL_ERROR);
292 		return (-1);
293 	}
294 	if (sscanf(ln, "%04d%02d%02d%02d%02d%02d",
295 	    &tm.tm_year, &tm.tm_mon, &tm.tm_mday,
296 	    &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
297 		_ftp_seterr(FTP_PROTOCOL_ERROR);
298 		return (-1);
299 	}
300 	tm.tm_mon--;
301 	tm.tm_year -= 1900;
302 	tm.tm_isdst = -1;
303 	t = timegm(&tm);
304 	if (t == (time_t)-1)
305 		t = time(NULL);
306 	us->mtime = t;
307 	us->atime = t;
308 	DEBUG(fprintf(stderr,
309 	    "last modified: [%04d-%02d-%02d %02d:%02d:%02d]\n",
310 	    tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
311 	    tm.tm_hour, tm.tm_min, tm.tm_sec));
312 	return (0);
313 }
314 
315 /*
316  * I/O functions for FTP
317  */
318 struct ftpio {
319 	int	 csd;		/* Control socket descriptor */
320 	int	 dsd;		/* Data socket descriptor */
321 	int	 dir;		/* Direction */
322 	int	 eof;		/* EOF reached */
323 	int	 err;		/* Error code */
324 };
325 
326 static int	 _ftp_readfn(void *, char *, int);
327 static int	 _ftp_writefn(void *, const char *, int);
328 static fpos_t	 _ftp_seekfn(void *, fpos_t, int);
329 static int	 _ftp_closefn(void *);
330 
331 static int
332 _ftp_readfn(void *v, char *buf, int len)
333 {
334 	struct ftpio *io;
335 	int r;
336 
337 	io = (struct ftpio *)v;
338 	if (io == NULL) {
339 		errno = EBADF;
340 		return (-1);
341 	}
342 	if (io->csd == -1 || io->dsd == -1 || io->dir == O_WRONLY) {
343 		errno = EBADF;
344 		return (-1);
345 	}
346 	if (io->err) {
347 		errno = io->err;
348 		return (-1);
349 	}
350 	if (io->eof)
351 		return (0);
352 	r = read(io->dsd, buf, len);
353 	if (r > 0)
354 		return (r);
355 	if (r == 0) {
356 		io->eof = 1;
357 		return (0);
358 	}
359 	if (errno != EINTR)
360 		io->err = errno;
361 	return (-1);
362 }
363 
364 static int
365 _ftp_writefn(void *v, const char *buf, int len)
366 {
367 	struct ftpio *io;
368 	int w;
369 
370 	io = (struct ftpio *)v;
371 	if (io == NULL) {
372 		errno = EBADF;
373 		return (-1);
374 	}
375 	if (io->csd == -1 || io->dsd == -1 || io->dir == O_RDONLY) {
376 		errno = EBADF;
377 		return (-1);
378 	}
379 	if (io->err) {
380 		errno = io->err;
381 		return (-1);
382 	}
383 	w = write(io->dsd, buf, len);
384 	if (w >= 0)
385 		return (w);
386 	if (errno != EINTR)
387 		io->err = errno;
388 	return (-1);
389 }
390 
391 static fpos_t
392 _ftp_seekfn(void *v, fpos_t pos __unused, int whence __unused)
393 {
394 	struct ftpio *io;
395 
396 	io = (struct ftpio *)v;
397 	if (io == NULL) {
398 		errno = EBADF;
399 		return (-1);
400 	}
401 	errno = ESPIPE;
402 	return (-1);
403 }
404 
405 static int
406 _ftp_closefn(void *v)
407 {
408 	struct ftpio *io;
409 	int r;
410 
411 	io = (struct ftpio *)v;
412 	if (io == NULL) {
413 		errno = EBADF;
414 		return (-1);
415 	}
416 	if (io->dir == -1)
417 		return (0);
418 	if (io->csd == -1 || io->dsd == -1) {
419 		errno = EBADF;
420 		return (-1);
421 	}
422 	close(io->dsd);
423 	io->dir = -1;
424 	io->dsd = -1;
425 	DEBUG(fprintf(stderr, "Waiting for final status\n"));
426 	r = _ftp_chkerr(io->csd);
427 	close(io->csd);
428 	free(io);
429 	return (r == FTP_TRANSFER_COMPLETE) ? 0 : -1;
430 }
431 
432 static FILE *
433 _ftp_setup(int csd, int dsd, int mode)
434 {
435 	struct ftpio *io;
436 	FILE *f;
437 
438 	if ((io = malloc(sizeof *io)) == NULL)
439 		return (NULL);
440 	io->csd = dup(csd);
441 	io->dsd = dsd;
442 	io->dir = mode;
443 	io->eof = io->err = 0;
444 	f = funopen(io, _ftp_readfn, _ftp_writefn, _ftp_seekfn, _ftp_closefn);
445 	if (f == NULL)
446 		free(io);
447 	return (f);
448 }
449 
450 /*
451  * Transfer file
452  */
453 static FILE *
454 _ftp_transfer(int cd, const char *oper, const char *file,
455     int mode, off_t offset, const char *flags)
456 {
457 	struct sockaddr_storage sa;
458 	struct sockaddr_in6 *sin6;
459 	struct sockaddr_in *sin4;
460 	int low, pasv, verbose;
461 	int e, sd = -1;
462 	socklen_t l;
463 	char *s;
464 	FILE *df;
465 
466 	/* check flags */
467 	low = CHECK_FLAG('l');
468 	pasv = CHECK_FLAG('p');
469 	verbose = CHECK_FLAG('v');
470 
471 	/* passive mode */
472 	if (!pasv)
473 		pasv = ((s = getenv("FTP_PASSIVE_MODE")) != NULL &&
474 		    strncasecmp(s, "no", 2) != 0);
475 
476 	/* find our own address, bind, and listen */
477 	l = sizeof sa;
478 	if (getsockname(cd, (struct sockaddr *)&sa, &l) == -1)
479 		goto sysouch;
480 	if (sa.ss_family == AF_INET6)
481 		unmappedaddr((struct sockaddr_in6 *)&sa);
482 
483 	/* open data socket */
484 	if ((sd = socket(sa.ss_family, SOCK_STREAM, IPPROTO_TCP)) == -1) {
485 		_fetch_syserr();
486 		return (NULL);
487 	}
488 
489 	if (pasv) {
490 		u_char addr[64];
491 		char *ln, *p;
492 		unsigned int i;
493 		int port;
494 
495 		/* send PASV command */
496 		if (verbose)
497 			_fetch_info("setting passive mode");
498 		switch (sa.ss_family) {
499 		case AF_INET:
500 			if ((e = _ftp_cmd(cd, "PASV")) != FTP_PASSIVE_MODE)
501 				goto ouch;
502 			break;
503 		case AF_INET6:
504 			if ((e = _ftp_cmd(cd, "EPSV")) != FTP_EPASSIVE_MODE) {
505 				if (e == -1)
506 					goto ouch;
507 				if ((e = _ftp_cmd(cd, "LPSV")) != FTP_LPASSIVE_MODE)
508 					goto ouch;
509 			}
510 			break;
511 		default:
512 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
513 			goto ouch;
514 		}
515 
516 		/*
517 		 * Find address and port number. The reply to the PASV command
518 		 * is IMHO the one and only weak point in the FTP protocol.
519 		 */
520 		ln = last_reply;
521 		switch (e) {
522 		case FTP_PASSIVE_MODE:
523 		case FTP_LPASSIVE_MODE:
524 			for (p = ln + 3; *p && !isdigit(*p); p++)
525 				/* nothing */ ;
526 			if (!*p) {
527 				e = FTP_PROTOCOL_ERROR;
528 				goto ouch;
529 			}
530 			l = (e == FTP_PASSIVE_MODE ? 6 : 21);
531 			for (i = 0; *p && i < l; i++, p++)
532 				addr[i] = strtol(p, &p, 10);
533 			if (i < l) {
534 				e = FTP_PROTOCOL_ERROR;
535 				goto ouch;
536 			}
537 			break;
538 		case FTP_EPASSIVE_MODE:
539 			for (p = ln + 3; *p && *p != '('; p++)
540 				/* nothing */ ;
541 			if (!*p) {
542 				e = FTP_PROTOCOL_ERROR;
543 				goto ouch;
544 			}
545 			++p;
546 			if (sscanf(p, "%c%c%c%d%c", &addr[0], &addr[1], &addr[2],
547 				&port, &addr[3]) != 5 ||
548 			    addr[0] != addr[1] ||
549 			    addr[0] != addr[2] || addr[0] != addr[3]) {
550 				e = FTP_PROTOCOL_ERROR;
551 				goto ouch;
552 			}
553 			break;
554 		}
555 
556 		/* seek to required offset */
557 		if (offset)
558 			if (_ftp_cmd(cd, "REST %lu", (u_long)offset) != FTP_FILE_OK)
559 				goto sysouch;
560 
561 		/* construct sockaddr for data socket */
562 		l = sizeof sa;
563 		if (getpeername(cd, (struct sockaddr *)&sa, &l) == -1)
564 			goto sysouch;
565 		if (sa.ss_family == AF_INET6)
566 			unmappedaddr((struct sockaddr_in6 *)&sa);
567 		switch (sa.ss_family) {
568 		case AF_INET6:
569 			sin6 = (struct sockaddr_in6 *)&sa;
570 			if (e == FTP_EPASSIVE_MODE)
571 				sin6->sin6_port = htons(port);
572 			else {
573 				bcopy(addr + 2, (char *)&sin6->sin6_addr, 16);
574 				bcopy(addr + 19, (char *)&sin6->sin6_port, 2);
575 			}
576 			break;
577 		case AF_INET:
578 			sin4 = (struct sockaddr_in *)&sa;
579 			if (e == FTP_EPASSIVE_MODE)
580 				sin4->sin_port = htons(port);
581 			else {
582 				bcopy(addr, (char *)&sin4->sin_addr, 4);
583 				bcopy(addr + 4, (char *)&sin4->sin_port, 2);
584 			}
585 			break;
586 		default:
587 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
588 			break;
589 		}
590 
591 		/* connect to data port */
592 		if (verbose)
593 			_fetch_info("opening data connection");
594 		if (connect(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
595 			goto sysouch;
596 
597 		/* make the server initiate the transfer */
598 		if (verbose)
599 			_fetch_info("initiating transfer");
600 		e = _ftp_cmd(cd, "%s %s", oper, _ftp_filename(file));
601 		if (e != FTP_CONNECTION_ALREADY_OPEN && e != FTP_OPEN_DATA_CONNECTION)
602 			goto ouch;
603 
604 	} else {
605 		u_int32_t a;
606 		u_short p;
607 		int arg, d;
608 		char *ap;
609 		char hname[INET6_ADDRSTRLEN];
610 
611 		switch (sa.ss_family) {
612 		case AF_INET6:
613 			((struct sockaddr_in6 *)&sa)->sin6_port = 0;
614 #ifdef IPV6_PORTRANGE
615 			arg = low ? IPV6_PORTRANGE_DEFAULT : IPV6_PORTRANGE_HIGH;
616 			if (setsockopt(sd, IPPROTO_IPV6, IPV6_PORTRANGE,
617 				(char *)&arg, sizeof(arg)) == -1)
618 				goto sysouch;
619 #endif
620 			break;
621 		case AF_INET:
622 			((struct sockaddr_in *)&sa)->sin_port = 0;
623 			arg = low ? IP_PORTRANGE_DEFAULT : IP_PORTRANGE_HIGH;
624 			if (setsockopt(sd, IPPROTO_IP, IP_PORTRANGE,
625 				(char *)&arg, sizeof arg) == -1)
626 				goto sysouch;
627 			break;
628 		}
629 		if (verbose)
630 			_fetch_info("binding data socket");
631 		if (bind(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
632 			goto sysouch;
633 		if (listen(sd, 1) == -1)
634 			goto sysouch;
635 
636 		/* find what port we're on and tell the server */
637 		if (getsockname(sd, (struct sockaddr *)&sa, &l) == -1)
638 			goto sysouch;
639 		switch (sa.ss_family) {
640 		case AF_INET:
641 			sin4 = (struct sockaddr_in *)&sa;
642 			a = ntohl(sin4->sin_addr.s_addr);
643 			p = ntohs(sin4->sin_port);
644 			e = _ftp_cmd(cd, "PORT %d,%d,%d,%d,%d,%d",
645 			    (a >> 24) & 0xff, (a >> 16) & 0xff,
646 			    (a >> 8) & 0xff, a & 0xff,
647 			    (p >> 8) & 0xff, p & 0xff);
648 			break;
649 		case AF_INET6:
650 #define UC(b)	(((int)b)&0xff)
651 			e = -1;
652 			sin6 = (struct sockaddr_in6 *)&sa;
653 			if (getnameinfo((struct sockaddr *)&sa, sa.ss_len,
654 				hname, sizeof(hname),
655 				NULL, 0, NI_NUMERICHOST) == 0) {
656 				e = _ftp_cmd(cd, "EPRT |%d|%s|%d|", 2, hname,
657 				    htons(sin6->sin6_port));
658 				if (e == -1)
659 					goto ouch;
660 			}
661 			if (e != FTP_OK) {
662 				ap = (char *)&sin6->sin6_addr;
663 				e = _ftp_cmd(cd,
664 				    "LPRT %d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",
665 				    6, 16,
666 				    UC(ap[0]), UC(ap[1]), UC(ap[2]), UC(ap[3]),
667 				    UC(ap[4]), UC(ap[5]), UC(ap[6]), UC(ap[7]),
668 				    UC(ap[8]), UC(ap[9]), UC(ap[10]), UC(ap[11]),
669 				    UC(ap[12]), UC(ap[13]), UC(ap[14]), UC(ap[15]),
670 				    2,
671 				    (ntohs(sin6->sin6_port) >> 8) & 0xff,
672 				    ntohs(sin6->sin6_port)        & 0xff);
673 			}
674 			break;
675 		default:
676 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
677 			goto ouch;
678 		}
679 		if (e != FTP_OK)
680 			goto ouch;
681 
682 		/* seek to required offset */
683 		if (offset)
684 			if (_ftp_cmd(cd, "REST %lu", (u_long)offset) != FTP_FILE_OK)
685 				goto sysouch;
686 
687 		/* make the server initiate the transfer */
688 		if (verbose)
689 			_fetch_info("initiating transfer");
690 		e = _ftp_cmd(cd, "%s %s", oper, _ftp_filename(file));
691 		if (e != FTP_OPEN_DATA_CONNECTION)
692 			goto ouch;
693 
694 		/* accept the incoming connection and go to town */
695 		if ((d = accept(sd, NULL, NULL)) == -1)
696 			goto sysouch;
697 		close(sd);
698 		sd = d;
699 	}
700 
701 	if ((df = _ftp_setup(cd, sd, mode)) == NULL)
702 		goto sysouch;
703 	return (df);
704 
705 sysouch:
706 	_fetch_syserr();
707 	if (sd >= 0)
708 		close(sd);
709 	return (NULL);
710 
711 ouch:
712 	if (e != -1)
713 		_ftp_seterr(e);
714 	if (sd >= 0)
715 		close(sd);
716 	return (NULL);
717 }
718 
719 /*
720  * Authenticate
721  */
722 static int
723 _ftp_authenticate(int cd, struct url *url, struct url *purl)
724 {
725 	const char *user, *pwd, *logname;
726 	char pbuf[MAXHOSTNAMELEN + MAXLOGNAME + 1];
727 	int e, len;
728 
729 	/* XXX FTP_AUTH, and maybe .netrc */
730 
731 	/* send user name and password */
732 	user = url->user;
733 	if (!user || !*user)
734 		user = getenv("FTP_LOGIN");
735 	if (!user || !*user)
736 		user = FTP_ANONYMOUS_USER;
737 	if (purl && url->port == _fetch_default_port(url->scheme))
738 		e = _ftp_cmd(cd, "USER %s@%s", user, url->host);
739 	else if (purl)
740 		e = _ftp_cmd(cd, "USER %s@%s@%d", user, url->host, url->port);
741 	else
742 		e = _ftp_cmd(cd, "USER %s", user);
743 
744 	/* did the server request a password? */
745 	if (e == FTP_NEED_PASSWORD) {
746 		pwd = url->pwd;
747 		if (!pwd || !*pwd)
748 			pwd = getenv("FTP_PASSWORD");
749 		if (!pwd || !*pwd) {
750 			if ((logname = getlogin()) == 0)
751 				logname = FTP_ANONYMOUS_USER;
752 			if ((len = snprintf(pbuf, MAXLOGNAME + 1, "%s@", logname)) < 0)
753 				len = 0;
754 			else if (len > MAXLOGNAME)
755 				len = MAXLOGNAME;
756 			gethostname(pbuf + len, sizeof pbuf - len);
757 			pwd = pbuf;
758 		}
759 		e = _ftp_cmd(cd, "PASS %s", pwd);
760 	}
761 
762 	return (e);
763 }
764 
765 /*
766  * Log on to FTP server
767  */
768 static int
769 _ftp_connect(struct url *url, struct url *purl, const char *flags)
770 {
771 	int cd, e, direct, verbose;
772 #ifdef INET6
773 	int af = AF_UNSPEC;
774 #else
775 	int af = AF_INET;
776 #endif
777 
778 	direct = CHECK_FLAG('d');
779 	verbose = CHECK_FLAG('v');
780 	if (CHECK_FLAG('4'))
781 		af = AF_INET;
782 	else if (CHECK_FLAG('6'))
783 		af = AF_INET6;
784 
785 	if (direct)
786 		purl = NULL;
787 
788 	/* check for proxy */
789 	if (purl) {
790 		/* XXX proxy authentication! */
791 		cd = _fetch_connect(purl->host, purl->port, af, verbose);
792 	} else {
793 		/* no proxy, go straight to target */
794 		cd = _fetch_connect(url->host, url->port, af, verbose);
795 		purl = NULL;
796 	}
797 
798 	/* check connection */
799 	if (cd == -1) {
800 		_fetch_syserr();
801 		return (NULL);
802 	}
803 
804 	/* expect welcome message */
805 	if ((e = _ftp_chkerr(cd)) != FTP_SERVICE_READY)
806 		goto fouch;
807 
808 	/* authenticate */
809 	if ((e = _ftp_authenticate(cd, url, purl)) != FTP_LOGGED_IN)
810 		goto fouch;
811 
812 	/* might as well select mode and type at once */
813 #ifdef FTP_FORCE_STREAM_MODE
814 	if ((e = _ftp_cmd(cd, "MODE S")) != FTP_OK) /* default is S */
815 		goto fouch;
816 #endif
817 	if ((e = _ftp_cmd(cd, "TYPE I")) != FTP_OK) /* default is A */
818 		goto fouch;
819 
820 	/* done */
821 	return (cd);
822 
823 fouch:
824 	if (e != -1)
825 		_ftp_seterr(e);
826 	close(cd);
827 	return (NULL);
828 }
829 
830 /*
831  * Disconnect from server
832  */
833 static void
834 _ftp_disconnect(int cd)
835 {
836 	(void)_ftp_cmd(cd, "QUIT");
837 	close(cd);
838 }
839 
840 /*
841  * Check if we're already connected
842  */
843 static int
844 _ftp_isconnected(struct url *url)
845 {
846 	return (cached_socket
847 	    && (strcmp(url->host, cached_host.host) == 0)
848 	    && (strcmp(url->user, cached_host.user) == 0)
849 	    && (strcmp(url->pwd, cached_host.pwd) == 0)
850 	    && (url->port == cached_host.port));
851 }
852 
853 /*
854  * Check the cache, reconnect if no luck
855  */
856 static int
857 _ftp_cached_connect(struct url *url, struct url *purl, const char *flags)
858 {
859 	int e, cd;
860 
861 	cd = -1;
862 
863 	/* set default port */
864 	if (!url->port)
865 		url->port = _fetch_default_port(url->scheme);
866 
867 	/* try to use previously cached connection */
868 	if (_ftp_isconnected(url)) {
869 		e = _ftp_cmd(cached_socket, "NOOP");
870 		if (e == FTP_OK || e == FTP_SYNTAX_ERROR)
871 			return (cached_socket);
872 	}
873 
874 	/* connect to server */
875 	if ((cd = _ftp_connect(url, purl, flags)) == -1)
876 		return (-1);
877 	if (cached_socket)
878 		_ftp_disconnect(cached_socket);
879 	cached_socket = cd;
880 	memcpy(&cached_host, url, sizeof *url);
881 	return (cd);
882 }
883 
884 /*
885  * Check the proxy settings
886  */
887 static struct url *
888 _ftp_get_proxy(void)
889 {
890 	struct url *purl;
891 	char *p;
892 
893 	if (((p = getenv("FTP_PROXY")) || (p = getenv("ftp_proxy")) ||
894 		(p = getenv("HTTP_PROXY")) || (p = getenv("http_proxy"))) &&
895 	    *p && (purl = fetchParseURL(p)) != NULL) {
896 		if (!*purl->scheme) {
897 			if (getenv("FTP_PROXY") || getenv("ftp_proxy"))
898 				strcpy(purl->scheme, SCHEME_FTP);
899 			else
900 				strcpy(purl->scheme, SCHEME_HTTP);
901 		}
902 		if (!purl->port)
903 			purl->port = _fetch_default_proxy_port(purl->scheme);
904 		if (strcasecmp(purl->scheme, SCHEME_FTP) == 0 ||
905 		    strcasecmp(purl->scheme, SCHEME_HTTP) == 0)
906 			return (purl);
907 		fetchFreeURL(purl);
908 	}
909 	return (NULL);
910 }
911 
912 /*
913  * Process an FTP request
914  */
915 FILE *
916 _ftp_request(struct url *url, const char *op, struct url_stat *us,
917     struct url *purl, const char *flags)
918 {
919 	int cd, oflag;
920 
921 	/* check if we should use HTTP instead */
922 	if (purl && strcasecmp(purl->scheme, SCHEME_HTTP) == 0) {
923 		if (strcmp(op, "STAT") == 0)
924 			return (_http_request(url, "HEAD", us, purl, flags));
925 		else if (strcmp(op, "RETR") == 0)
926 			return (_http_request(url, "GET", us, purl, flags));
927 		/*
928 		 * Our HTTP code doesn't support PUT requests yet, so try
929 		 * a direct connection.
930 		 */
931 	}
932 
933 	/* connect to server */
934 	cd = _ftp_cached_connect(url, purl, flags);
935 	if (purl)
936 		fetchFreeURL(purl);
937 	if (cd == NULL)
938 		return (NULL);
939 
940 	/* change directory */
941 	if (_ftp_cwd(cd, url->doc) == -1)
942 		return (NULL);
943 
944 	/* stat file */
945 	if (us && _ftp_stat(cd, url->doc, us) == -1
946 	    && fetchLastErrCode != FETCH_PROTO
947 	    && fetchLastErrCode != FETCH_UNAVAIL)
948 		return (NULL);
949 
950 	/* just a stat */
951 	if (strcmp(op, "STAT") == 0)
952 		return (FILE *)1; /* bogus return value */
953 	if (strcmp(op, "STOR") == 0 || strcmp(op, "APPE") == 0)
954 		oflag = O_WRONLY;
955 	else
956 		oflag = O_RDONLY;
957 
958 	/* initiate the transfer */
959 	return (_ftp_transfer(cd, op, url->doc, oflag, url->offset, flags));
960 }
961 
962 /*
963  * Get and stat file
964  */
965 FILE *
966 fetchXGetFTP(struct url *url, struct url_stat *us, const char *flags)
967 {
968 	return (_ftp_request(url, "RETR", us, _ftp_get_proxy(), flags));
969 }
970 
971 /*
972  * Get file
973  */
974 FILE *
975 fetchGetFTP(struct url *url, const char *flags)
976 {
977 	return (fetchXGetFTP(url, NULL, flags));
978 }
979 
980 /*
981  * Put file
982  */
983 FILE *
984 fetchPutFTP(struct url *url, const char *flags)
985 {
986 
987 	return _ftp_request(url, CHECK_FLAG('a') ? "APPE" : "STOR", NULL,
988 	    _ftp_get_proxy(), flags);
989 }
990 
991 /*
992  * Get file stats
993  */
994 int
995 fetchStatFTP(struct url *url, struct url_stat *us, const char *flags)
996 {
997 
998 	if (_ftp_request(url, "STAT", us, _ftp_get_proxy(), flags) == NULL)
999 		return (-1);
1000 	return (0);
1001 }
1002 
1003 /*
1004  * List a directory
1005  */
1006 struct url_ent *
1007 fetchListFTP(struct url *url __unused, const char *flags __unused)
1008 {
1009 	warnx("fetchListFTP(): not implemented");
1010 	return (NULL);
1011 }
1012