xref: /freebsd/lib/libfetch/ftp.c (revision d15f2551b25f79ddcbe289faa95e655100b952da)
1 /*-
2  * SPDX-License-Identifier: (BSD-3-Clause AND Beerware)
3  *
4  * Copyright (c) 1998-2011 Dag-Erling Smørgrav
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer
12  *    in this position and unchanged.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. The name of the author may not be used to endorse or promote products
17  *    derived from this software without specific prior written permission
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 
31 #include <sys/cdefs.h>
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 Smørgrav
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 <stdint.h>
70 #include <stdio.h>
71 #include <stdlib.h>
72 #include <string.h>
73 #include <time.h>
74 #include <unistd.h>
75 
76 #include "fetch.h"
77 #include "common.h"
78 #include "ftperr.h"
79 
80 #define FTP_ANONYMOUS_USER	"anonymous"
81 
82 #define FTP_CONNECTION_ALREADY_OPEN	125
83 #define FTP_OPEN_DATA_CONNECTION	150
84 #define FTP_OK				200
85 #define FTP_FILE_STATUS			213
86 #define FTP_SERVICE_READY		220
87 #define FTP_TRANSFER_COMPLETE		226
88 #define FTP_PASSIVE_MODE		227
89 #define FTP_LPASSIVE_MODE		228
90 #define FTP_EPASSIVE_MODE		229
91 #define FTP_LOGGED_IN			230
92 #define FTP_FILE_ACTION_OK		250
93 #define FTP_DIRECTORY_CREATED		257 /* multiple meanings */
94 #define FTP_FILE_CREATED		257 /* multiple meanings */
95 #define FTP_WORKING_DIRECTORY		257 /* multiple meanings */
96 #define FTP_NEED_PASSWORD		331
97 #define FTP_NEED_ACCOUNT		332
98 #define FTP_FILE_OK			350
99 #define FTP_SYNTAX_ERROR		500
100 #define FTP_PROTOCOL_ERROR		999
101 
102 static struct url cached_host;
103 static conn_t	*cached_connection;
104 
105 #define isftpreply(foo)				\
106 	(isdigit((unsigned char)foo[0]) &&	\
107 	    isdigit((unsigned char)foo[1]) &&	\
108 	    isdigit((unsigned char)foo[2]) &&	\
109 	    (foo[3] == ' ' || foo[3] == '\0'))
110 #define isftpinfo(foo) \
111 	(isdigit((unsigned char)foo[0]) &&	\
112 	    isdigit((unsigned char)foo[1]) &&	\
113 	    isdigit((unsigned char)foo[2]) &&	\
114 	    foo[3] == '-')
115 
116 /*
117  * Translate IPv4 mapped IPv6 address to IPv4 address
118  */
119 static void
120 unmappedaddr(struct sockaddr_in6 *sin6)
121 {
122 	struct sockaddr_in *sin4;
123 	u_int32_t addr;
124 	int port;
125 
126 	if (sin6->sin6_family != AF_INET6 ||
127 	    !IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
128 		return;
129 	sin4 = (struct sockaddr_in *)sin6;
130 	addr = *(u_int32_t *)(uintptr_t)&sin6->sin6_addr.s6_addr[12];
131 	port = sin6->sin6_port;
132 	memset(sin4, 0, sizeof(struct sockaddr_in));
133 	sin4->sin_addr.s_addr = addr;
134 	sin4->sin_port = port;
135 	sin4->sin_family = AF_INET;
136 	sin4->sin_len = sizeof(struct sockaddr_in);
137 }
138 
139 /*
140  * Get server response
141  */
142 static int
143 ftp_chkerr(conn_t *conn)
144 {
145 	ssize_t rlen;
146 
147 	if ((rlen = fetch_getln(conn)) < 0) {
148 		fetch_syserr();
149 		return (-1);
150 	}
151 
152 	if (isftpinfo(conn->line)) {
153 		while (rlen && !isftpreply(conn->line)) {
154 			if ((rlen = fetch_getln(conn)) < 0) {
155 				fetch_syserr();
156 				return (-1);
157 			}
158 		}
159 	}
160 
161 	if (!isftpreply(conn->line)) {
162 		ftp_seterr(FTP_PROTOCOL_ERROR);
163 		return (-1);
164 	}
165 
166 	conn->err = (conn->line[0] - '0') * 100
167 	    + (conn->line[1] - '0') * 10
168 	    + (conn->line[2] - '0');
169 
170 	return (conn->err);
171 }
172 
173 /*
174  * Send a command and check reply
175  */
176 static int
177 ftp_cmd(conn_t *conn, const char *fmt, ...)
178 {
179 	va_list ap;
180 	size_t len;
181 	char *msg;
182 	int r;
183 
184 	va_start(ap, fmt);
185 	len = vasprintf(&msg, fmt, ap);
186 	va_end(ap);
187 
188 	if (msg == NULL) {
189 		errno = ENOMEM;
190 		fetch_syserr();
191 		return (-1);
192 	}
193 
194 	r = fetch_putln(conn, msg, len);
195 	free(msg);
196 
197 	if (r == -1) {
198 		fetch_syserr();
199 		return (-1);
200 	}
201 
202 	return (ftp_chkerr(conn));
203 }
204 
205 /*
206  * Return a pointer to the filename part of a path
207  */
208 static const char *
209 ftp_filename(const char *file, int *len, int *type)
210 {
211 	const char *s;
212 
213 	if ((s = strrchr(file, '/')) == NULL)
214 		s = file;
215 	else
216 		s = s + 1;
217 	*len = strlen(s);
218 	if (*len > 7 && strncmp(s + *len - 7, ";type=", 6) == 0) {
219 		*type = s[*len - 1];
220 		*len -= 7;
221 	} else {
222 		*type = '\0';
223 	}
224 	return (s);
225 }
226 
227 /*
228  * Get current working directory from the reply to a CWD, PWD or CDUP
229  * command.
230  */
231 static int
232 ftp_pwd(conn_t *conn, char *pwd, size_t pwdlen)
233 {
234 	char *src, *dst, *end;
235 	int q;
236 
237 	if (conn->err != FTP_WORKING_DIRECTORY &&
238 	    conn->err != FTP_FILE_ACTION_OK)
239 		return (FTP_PROTOCOL_ERROR);
240 	end = conn->line + conn->linelen;
241 	src = conn->line + 4;
242 	if (src >= end || *src++ != '"')
243 		return (FTP_PROTOCOL_ERROR);
244 	for (q = 0, dst = pwd; src < end && pwdlen--; ++src) {
245 		if (!q && *src == '"')
246 			q = 1;
247 		else if (q && *src != '"')
248 			break;
249 		else if (q)
250 			*dst++ = '"', q = 0;
251 		else
252 			*dst++ = *src;
253 	}
254 	if (!pwdlen)
255 		return (FTP_PROTOCOL_ERROR);
256 	*dst = '\0';
257 #if 0
258 	DEBUGF("pwd: [%s]\n", pwd);
259 #endif
260 	return (FTP_OK);
261 }
262 
263 /*
264  * Change working directory to the directory that contains the specified
265  * file.
266  */
267 static int
268 ftp_cwd(conn_t *conn, const char *file)
269 {
270 	const char *beg, *end;
271 	char pwd[PATH_MAX];
272 	int e, i, len;
273 
274 	/* If no slashes in name, no need to change dirs. */
275 	if ((end = strrchr(file, '/')) == NULL)
276 		return (0);
277 	if ((e = ftp_cmd(conn, "PWD")) != FTP_WORKING_DIRECTORY ||
278 	    (e = ftp_pwd(conn, pwd, sizeof(pwd))) != FTP_OK) {
279 		ftp_seterr(e);
280 		return (-1);
281 	}
282 	for (;;) {
283 		len = strlen(pwd);
284 
285 		/* Look for a common prefix between PWD and dir to fetch. */
286 		for (i = 0; i <= len && i <= end - file; ++i)
287 			if (pwd[i] != file[i])
288 				break;
289 #if 0
290 		DEBUGF("have: [%.*s|%s]\n", i, pwd, pwd + i);
291 		DEBUGF("want: [%.*s|%s]\n", i, file, file + i);
292 #endif
293 		/* Keep going up a dir until we have a matching prefix. */
294 		if (pwd[i] == '\0' && (file[i - 1] == '/' || file[i] == '/'))
295 			break;
296 		if ((e = ftp_cmd(conn, "CDUP")) != FTP_FILE_ACTION_OK ||
297 		    (e = ftp_cmd(conn, "PWD")) != FTP_WORKING_DIRECTORY ||
298 		    (e = ftp_pwd(conn, pwd, sizeof(pwd))) != FTP_OK) {
299 			ftp_seterr(e);
300 			return (-1);
301 		}
302 	}
303 
304 #ifdef FTP_COMBINE_CWDS
305 	/* Skip leading slashes, even "////". */
306 	for (beg = file + i; beg < end && *beg == '/'; ++beg, ++i)
307 		/* nothing */ ;
308 
309 	/* If there is no trailing dir, we're already there. */
310 	if (beg >= end)
311 		return (0);
312 
313 	/* Change to the directory all in one chunk (e.g., foo/bar/baz). */
314 	e = ftp_cmd(conn, "CWD %.*s", (int)(end - beg), beg);
315 	if (e == FTP_FILE_ACTION_OK)
316 		return (0);
317 #endif /* FTP_COMBINE_CWDS */
318 
319 	/* That didn't work so go back to legacy behavior (multiple CWDs). */
320 	for (beg = file + i; beg < end; beg = file + i + 1) {
321 		while (*beg == '/')
322 			++beg, ++i;
323 		for (++i; file + i < end && file[i] != '/'; ++i)
324 			/* nothing */ ;
325 		e = ftp_cmd(conn, "CWD %.*s", file + i - beg, beg);
326 		if (e != FTP_FILE_ACTION_OK) {
327 			ftp_seterr(e);
328 			return (-1);
329 		}
330 	}
331 	return (0);
332 }
333 
334 /*
335  * Set transfer mode and data type
336  */
337 static int
338 ftp_mode_type(conn_t *conn, int mode, int type)
339 {
340 	int e;
341 
342 	switch (mode) {
343 	case 0:
344 	case 's':
345 		mode = 'S';
346 	case 'S':
347 		break;
348 	default:
349 		return (FTP_PROTOCOL_ERROR);
350 	}
351 	if ((e = ftp_cmd(conn, "MODE %c", mode)) != FTP_OK) {
352 		if (mode == 'S') {
353 			/*
354 			 * Stream mode is supposed to be the default - so
355 			 * much so that some servers not only do not
356 			 * support any other mode, but do not support the
357 			 * MODE command at all.
358 			 *
359 			 * If "MODE S" fails, it is unlikely that we
360 			 * previously succeeded in setting a different
361 			 * mode.  Therefore, we simply hope that the
362 			 * server is already in the correct mode, and
363 			 * silently ignore the failure.
364 			 */
365 		} else {
366 			return (e);
367 		}
368 	}
369 
370 	switch (type) {
371 	case 0:
372 	case 'i':
373 		type = 'I';
374 	case 'I':
375 		break;
376 	case 'a':
377 		type = 'A';
378 	case 'A':
379 		break;
380 	case 'd':
381 		type = 'D';
382 	case 'D':
383 		/* can't handle yet */
384 	default:
385 		return (FTP_PROTOCOL_ERROR);
386 	}
387 	if ((e = ftp_cmd(conn, "TYPE %c", type)) != FTP_OK)
388 		return (e);
389 
390 	return (FTP_OK);
391 }
392 
393 /*
394  * Request and parse file stats
395  */
396 static int
397 ftp_stat(conn_t *conn, const char *file, struct url_stat *us)
398 {
399 	char *ln;
400 	const char *filename;
401 	int filenamelen, type;
402 	struct tm tm;
403 	time_t t;
404 	int e;
405 
406 	us->size = -1;
407 	us->atime = us->mtime = 0;
408 
409 	filename = ftp_filename(file, &filenamelen, &type);
410 
411 	if ((e = ftp_mode_type(conn, 0, type)) != FTP_OK) {
412 		ftp_seterr(e);
413 		return (-1);
414 	}
415 
416 	e = ftp_cmd(conn, "SIZE %.*s", filenamelen, filename);
417 	if (e != FTP_FILE_STATUS) {
418 		ftp_seterr(e);
419 		return (-1);
420 	}
421 	for (ln = conn->line + 4; *ln && isspace((unsigned char)*ln); ln++)
422 		/* nothing */ ;
423 	for (us->size = 0; *ln && isdigit((unsigned char)*ln); ln++)
424 		us->size = us->size * 10 + *ln - '0';
425 	if (*ln && !isspace((unsigned char)*ln)) {
426 		ftp_seterr(FTP_PROTOCOL_ERROR);
427 		us->size = -1;
428 		return (-1);
429 	}
430 	if (us->size == 0)
431 		us->size = -1;
432 	DEBUGF("size: [%lld]\n", (long long)us->size);
433 
434 	e = ftp_cmd(conn, "MDTM %.*s", filenamelen, filename);
435 	if (e != FTP_FILE_STATUS) {
436 		ftp_seterr(e);
437 		return (-1);
438 	}
439 	for (ln = conn->line + 4; *ln && isspace((unsigned char)*ln); ln++)
440 		/* nothing */ ;
441 	switch (strspn(ln, "0123456789")) {
442 	case 14:
443 		break;
444 	case 15:
445 		ln++;
446 		ln[0] = '2';
447 		ln[1] = '0';
448 		break;
449 	default:
450 		ftp_seterr(FTP_PROTOCOL_ERROR);
451 		return (-1);
452 	}
453 	if (sscanf(ln, "%04d%02d%02d%02d%02d%02d",
454 	    &tm.tm_year, &tm.tm_mon, &tm.tm_mday,
455 	    &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
456 		ftp_seterr(FTP_PROTOCOL_ERROR);
457 		return (-1);
458 	}
459 	tm.tm_mon--;
460 	tm.tm_year -= 1900;
461 	tm.tm_isdst = -1;
462 	t = timegm(&tm);
463 	if (t == (time_t)-1)
464 		t = time(NULL);
465 	us->mtime = t;
466 	us->atime = t;
467 	DEBUGF("last modified: [%04d-%02d-%02d %02d:%02d:%02d]\n",
468 	    tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
469 	    tm.tm_hour, tm.tm_min, tm.tm_sec);
470 	return (0);
471 }
472 
473 /*
474  * I/O functions for FTP
475  */
476 struct ftpio {
477 	conn_t	*cconn;		/* Control connection */
478 	conn_t	*dconn;		/* Data connection */
479 	int	 dir;		/* Direction */
480 	int	 eof;		/* EOF reached */
481 	int	 err;		/* Error code */
482 };
483 
484 static int	 ftp_readfn(void *, char *, int);
485 static int	 ftp_writefn(void *, const char *, int);
486 static fpos_t	 ftp_seekfn(void *, fpos_t, int);
487 static int	 ftp_closefn(void *);
488 
489 static int
490 ftp_readfn(void *v, char *buf, int len)
491 {
492 	struct ftpio *io;
493 	int r;
494 
495 	io = (struct ftpio *)v;
496 	if (io == NULL) {
497 		errno = EBADF;
498 		return (-1);
499 	}
500 	if (io->cconn == NULL || io->dconn == NULL || io->dir == O_WRONLY) {
501 		errno = EBADF;
502 		return (-1);
503 	}
504 	if (io->err) {
505 		errno = io->err;
506 		return (-1);
507 	}
508 	if (io->eof)
509 		return (0);
510 	r = fetch_read(io->dconn, buf, len);
511 	if (r > 0)
512 		return (r);
513 	if (r == 0) {
514 		io->eof = 1;
515 		return (0);
516 	}
517 	if (errno != EINTR)
518 		io->err = errno;
519 	return (-1);
520 }
521 
522 static int
523 ftp_writefn(void *v, const char *buf, int len)
524 {
525 	struct ftpio *io;
526 	int w;
527 
528 	io = (struct ftpio *)v;
529 	if (io == NULL) {
530 		errno = EBADF;
531 		return (-1);
532 	}
533 	if (io->cconn == NULL || io->dconn == NULL || io->dir == O_RDONLY) {
534 		errno = EBADF;
535 		return (-1);
536 	}
537 	if (io->err) {
538 		errno = io->err;
539 		return (-1);
540 	}
541 	w = fetch_write(io->dconn, buf, len);
542 	if (w >= 0)
543 		return (w);
544 	if (errno != EINTR)
545 		io->err = errno;
546 	return (-1);
547 }
548 
549 static fpos_t
550 ftp_seekfn(void *v, fpos_t pos __unused, int whence __unused)
551 {
552 	struct ftpio *io;
553 
554 	io = (struct ftpio *)v;
555 	if (io == NULL) {
556 		errno = EBADF;
557 		return (-1);
558 	}
559 	errno = ESPIPE;
560 	return (-1);
561 }
562 
563 static int
564 ftp_closefn(void *v)
565 {
566 	struct ftpio *io;
567 	int r;
568 
569 	io = (struct ftpio *)v;
570 	if (io == NULL) {
571 		errno = EBADF;
572 		return (-1);
573 	}
574 	if (io->dir == -1)
575 		return (0);
576 	if (io->cconn == NULL || io->dconn == NULL) {
577 		errno = EBADF;
578 		return (-1);
579 	}
580 	fetch_close(io->dconn);
581 	io->dir = -1;
582 	io->dconn = NULL;
583 	DEBUGF("Waiting for final status\n");
584 	r = ftp_chkerr(io->cconn);
585 	if (io->cconn == cached_connection && io->cconn->ref == 1)
586 		cached_connection = NULL;
587 	fetch_close(io->cconn);
588 	free(io);
589 	return (r == FTP_TRANSFER_COMPLETE) ? 0 : -1;
590 }
591 
592 static FILE *
593 ftp_setup(conn_t *cconn, conn_t *dconn, int mode)
594 {
595 	struct ftpio *io;
596 	FILE *f;
597 
598 	if (cconn == NULL || dconn == NULL)
599 		return (NULL);
600 	if ((io = malloc(sizeof(*io))) == NULL)
601 		return (NULL);
602 	io->cconn = cconn;
603 	io->dconn = dconn;
604 	io->dir = mode;
605 	io->eof = io->err = 0;
606 	f = funopen(io, ftp_readfn, ftp_writefn, ftp_seekfn, ftp_closefn);
607 	if (f == NULL)
608 		free(io);
609 	return (f);
610 }
611 
612 /*
613  * Transfer file
614  */
615 static FILE *
616 ftp_transfer(conn_t *conn, const char *oper, const char *file,
617     int mode, off_t offset, const char *flags)
618 {
619 	struct sockaddr_storage sa;
620 	struct sockaddr_in6 *sin6;
621 	struct sockaddr_in *sin4;
622 	const char *bindaddr;
623 	const char *filename;
624 	int filenamelen, type;
625 	int low, pasv, verbose;
626 	int e, sd = -1;
627 	socklen_t l;
628 	char *s;
629 	FILE *df;
630 
631 	/* check flags */
632 	low = CHECK_FLAG('l');
633 	pasv = CHECK_FLAG('p') || !CHECK_FLAG('P');
634 	verbose = CHECK_FLAG('v');
635 
636 	/* passive mode */
637 	if ((s = getenv("FTP_PASSIVE_MODE")) != NULL)
638 		pasv = (strncasecmp(s, "no", 2) != 0);
639 
640 	/* isolate filename */
641 	filename = ftp_filename(file, &filenamelen, &type);
642 
643 	/* set transfer mode and data type */
644 	if ((e = ftp_mode_type(conn, 0, type)) != FTP_OK)
645 		goto ouch;
646 
647 	/* find our own address, bind, and listen */
648 	l = sizeof(sa);
649 	if (getsockname(conn->sd, (struct sockaddr *)&sa, &l) == -1)
650 		goto sysouch;
651 	if (sa.ss_family == AF_INET6)
652 		unmappedaddr((struct sockaddr_in6 *)&sa);
653 
654 	/* open data socket */
655 	if ((sd = socket(sa.ss_family, SOCK_STREAM, IPPROTO_TCP)) == -1) {
656 		fetch_syserr();
657 		return (NULL);
658 	}
659 
660 	if (pasv) {
661 		u_char addr[64];
662 		char *ln, *p;
663 		unsigned int i;
664 		int port;
665 
666 		/* send PASV command */
667 		if (verbose)
668 			fetch_info("setting passive mode");
669 		switch (sa.ss_family) {
670 		case AF_INET:
671 			if ((e = ftp_cmd(conn, "PASV")) != FTP_PASSIVE_MODE)
672 				goto ouch;
673 			break;
674 		case AF_INET6:
675 			if ((e = ftp_cmd(conn, "EPSV")) != FTP_EPASSIVE_MODE) {
676 				if (e == -1)
677 					goto ouch;
678 				if ((e = ftp_cmd(conn, "LPSV")) !=
679 				    FTP_LPASSIVE_MODE)
680 					goto ouch;
681 			}
682 			break;
683 		default:
684 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
685 			goto ouch;
686 		}
687 
688 		/*
689 		 * Find address and port number. The reply to the PASV command
690 		 * is IMHO the one and only weak point in the FTP protocol.
691 		 */
692 		ln = conn->line;
693 		switch (e) {
694 		case FTP_PASSIVE_MODE:
695 		case FTP_LPASSIVE_MODE:
696 			for (p = ln + 3; *p && !isdigit((unsigned char)*p); p++)
697 				/* nothing */ ;
698 			if (!*p) {
699 				e = FTP_PROTOCOL_ERROR;
700 				goto ouch;
701 			}
702 			l = (e == FTP_PASSIVE_MODE ? 6 : 21);
703 			for (i = 0; *p && i < l; i++, p++) {
704 				addr[i] = strtol(p, &p, 10);
705 				if (*p == '\0' && i < l - 1)
706 					break;
707 			}
708 			if (i < l) {
709 				e = FTP_PROTOCOL_ERROR;
710 				goto ouch;
711 			}
712 			break;
713 		case FTP_EPASSIVE_MODE:
714 			for (p = ln + 3; *p && *p != '('; p++)
715 				/* nothing */ ;
716 			if (!*p) {
717 				e = FTP_PROTOCOL_ERROR;
718 				goto ouch;
719 			}
720 			++p;
721 			if (sscanf(p, "%c%c%c%d%c", &addr[0], &addr[1], &addr[2],
722 				&port, &addr[3]) != 5 ||
723 			    addr[0] != addr[1] ||
724 			    addr[0] != addr[2] || addr[0] != addr[3]) {
725 				e = FTP_PROTOCOL_ERROR;
726 				goto ouch;
727 			}
728 			break;
729 		}
730 
731 		/* seek to required offset */
732 		if (offset)
733 			if (ftp_cmd(conn, "REST %lu", (u_long)offset) != FTP_FILE_OK)
734 				goto sysouch;
735 
736 		/* construct sockaddr for data socket */
737 		l = sizeof(sa);
738 		if (getpeername(conn->sd, (struct sockaddr *)&sa, &l) == -1)
739 			goto sysouch;
740 		if (sa.ss_family == AF_INET6)
741 			unmappedaddr((struct sockaddr_in6 *)&sa);
742 		switch (sa.ss_family) {
743 		case AF_INET6:
744 			sin6 = (struct sockaddr_in6 *)&sa;
745 			if (e == FTP_EPASSIVE_MODE)
746 				sin6->sin6_port = htons(port);
747 			else {
748 				memcpy(&sin6->sin6_addr, addr + 2, 16);
749 				memcpy(&sin6->sin6_port, addr + 19, 2);
750 			}
751 			break;
752 		case AF_INET:
753 			sin4 = (struct sockaddr_in *)&sa;
754 			if (e == FTP_EPASSIVE_MODE)
755 				sin4->sin_port = htons(port);
756 			else {
757 				memcpy(&sin4->sin_addr, addr, 4);
758 				memcpy(&sin4->sin_port, addr + 4, 2);
759 			}
760 			break;
761 		default:
762 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
763 			break;
764 		}
765 
766 		/* connect to data port */
767 		if (verbose)
768 			fetch_info("opening data connection");
769 		bindaddr = getenv("FETCH_BIND_ADDRESS");
770 		if (bindaddr != NULL && *bindaddr != '\0' &&
771 		    (e = fetch_bind(sd, sa.ss_family, bindaddr)) != 0)
772 			goto ouch;
773 		if (connect(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
774 			goto sysouch;
775 
776 		/* make the server initiate the transfer */
777 		if (verbose)
778 			fetch_info("initiating transfer");
779 		e = ftp_cmd(conn, "%s %.*s", oper, filenamelen, filename);
780 		if (e != FTP_CONNECTION_ALREADY_OPEN && e != FTP_OPEN_DATA_CONNECTION)
781 			goto ouch;
782 
783 	} else {
784 		u_int32_t a;
785 		u_short p;
786 		int arg, d;
787 		char *ap;
788 		char hname[INET6_ADDRSTRLEN];
789 
790 		switch (sa.ss_family) {
791 		case AF_INET6:
792 			((struct sockaddr_in6 *)&sa)->sin6_port = 0;
793 #ifdef IPV6_PORTRANGE
794 			arg = low ? IPV6_PORTRANGE_DEFAULT : IPV6_PORTRANGE_HIGH;
795 			if (setsockopt(sd, IPPROTO_IPV6, IPV6_PORTRANGE,
796 				(char *)&arg, sizeof(arg)) == -1)
797 				goto sysouch;
798 #endif
799 			break;
800 		case AF_INET:
801 			((struct sockaddr_in *)&sa)->sin_port = 0;
802 			arg = low ? IP_PORTRANGE_DEFAULT : IP_PORTRANGE_HIGH;
803 			if (setsockopt(sd, IPPROTO_IP, IP_PORTRANGE,
804 				(char *)&arg, sizeof(arg)) == -1)
805 				goto sysouch;
806 			break;
807 		}
808 		if (verbose)
809 			fetch_info("binding data socket");
810 		if (bind(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
811 			goto sysouch;
812 		if (listen(sd, 1) == -1)
813 			goto sysouch;
814 
815 		/* find what port we're on and tell the server */
816 		if (getsockname(sd, (struct sockaddr *)&sa, &l) == -1)
817 			goto sysouch;
818 		switch (sa.ss_family) {
819 		case AF_INET:
820 			sin4 = (struct sockaddr_in *)&sa;
821 			a = ntohl(sin4->sin_addr.s_addr);
822 			p = ntohs(sin4->sin_port);
823 			e = ftp_cmd(conn, "PORT %d,%d,%d,%d,%d,%d",
824 			    (a >> 24) & 0xff, (a >> 16) & 0xff,
825 			    (a >> 8) & 0xff, a & 0xff,
826 			    (p >> 8) & 0xff, p & 0xff);
827 			break;
828 		case AF_INET6:
829 #define UC(b)	(((int)b)&0xff)
830 			e = -1;
831 			sin6 = (struct sockaddr_in6 *)&sa;
832 			sin6->sin6_scope_id = 0;
833 			if (getnameinfo((struct sockaddr *)&sa, sa.ss_len,
834 				hname, sizeof(hname),
835 				NULL, 0, NI_NUMERICHOST) == 0) {
836 				e = ftp_cmd(conn, "EPRT |%d|%s|%d|", 2, hname,
837 				    htons(sin6->sin6_port));
838 				if (e == -1)
839 					goto ouch;
840 			}
841 			if (e != FTP_OK) {
842 				ap = (char *)&sin6->sin6_addr;
843 				e = ftp_cmd(conn,
844 				    "LPRT %d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",
845 				    6, 16,
846 				    UC(ap[0]), UC(ap[1]), UC(ap[2]), UC(ap[3]),
847 				    UC(ap[4]), UC(ap[5]), UC(ap[6]), UC(ap[7]),
848 				    UC(ap[8]), UC(ap[9]), UC(ap[10]), UC(ap[11]),
849 				    UC(ap[12]), UC(ap[13]), UC(ap[14]), UC(ap[15]),
850 				    2,
851 				    (ntohs(sin6->sin6_port) >> 8) & 0xff,
852 				    ntohs(sin6->sin6_port)        & 0xff);
853 			}
854 			break;
855 		default:
856 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
857 			goto ouch;
858 		}
859 		if (e != FTP_OK)
860 			goto ouch;
861 
862 		/* seek to required offset */
863 		if (offset)
864 			if (ftp_cmd(conn, "REST %ju", (uintmax_t)offset) != FTP_FILE_OK)
865 				goto sysouch;
866 
867 		/* make the server initiate the transfer */
868 		if (verbose)
869 			fetch_info("initiating transfer");
870 		e = ftp_cmd(conn, "%s %.*s", oper, filenamelen, filename);
871 		if (e != FTP_CONNECTION_ALREADY_OPEN && e != FTP_OPEN_DATA_CONNECTION)
872 			goto ouch;
873 
874 		/* accept the incoming connection and go to town */
875 		if ((d = accept(sd, NULL, NULL)) == -1)
876 			goto sysouch;
877 		close(sd);
878 		sd = d;
879 	}
880 
881 	if ((df = ftp_setup(conn, fetch_reopen(sd), mode)) == NULL)
882 		goto sysouch;
883 	return (df);
884 
885 sysouch:
886 	fetch_syserr();
887 	if (sd >= 0)
888 		close(sd);
889 	return (NULL);
890 
891 ouch:
892 	if (e != -1)
893 		ftp_seterr(e);
894 	if (sd >= 0)
895 		close(sd);
896 	return (NULL);
897 }
898 
899 /*
900  * Authenticate
901  */
902 static int
903 ftp_authenticate(conn_t *conn, struct url *url, struct url *purl)
904 {
905 	const char *user, *pwd, *logname;
906 	char pbuf[MAXHOSTNAMELEN + MAXLOGNAME + 1];
907 	int e, len;
908 
909 	/* XXX FTP_AUTH, and maybe .netrc */
910 
911 	/* send user name and password */
912 	if (url->user[0] == '\0')
913 		fetch_netrc_auth(url);
914 	user = url->user;
915 	if (*user == '\0')
916 		if ((user = getenv("FTP_LOGIN")) != NULL)
917 			DEBUGF("FTP_LOGIN=%s\n", user);
918 	if (user == NULL || *user == '\0')
919 		user = FTP_ANONYMOUS_USER;
920 	if (purl && url->port == fetch_default_port(url->scheme))
921 		e = ftp_cmd(conn, "USER %s@%s", user, url->host);
922 	else if (purl)
923 		e = ftp_cmd(conn, "USER %s@%s@%d", user, url->host, url->port);
924 	else
925 		e = ftp_cmd(conn, "USER %s", user);
926 
927 	/* did the server request a password? */
928 	if (e == FTP_NEED_PASSWORD) {
929 		pwd = url->pwd;
930 		if (*pwd == '\0')
931 			if ((pwd = getenv("FTP_PASSWORD")) != NULL)
932 				DEBUGF("FTP_PASSWORD=%s\n", pwd);
933 		if (pwd == NULL || *pwd == '\0') {
934 			if ((logname = getlogin()) == NULL)
935 				logname = FTP_ANONYMOUS_USER;
936 			if ((len = snprintf(pbuf, MAXLOGNAME + 1, "%s@", logname)) < 0)
937 				len = 0;
938 			else if (len > MAXLOGNAME)
939 				len = MAXLOGNAME;
940 			gethostname(pbuf + len, sizeof(pbuf) - len);
941 			pwd = pbuf;
942 		}
943 		e = ftp_cmd(conn, "PASS %s", pwd);
944 	}
945 
946 	return (e);
947 }
948 
949 /*
950  * Log on to FTP server
951  */
952 static conn_t *
953 ftp_connect(struct url *url, struct url *purl, const char *flags)
954 {
955 	conn_t *conn;
956 	int e, direct, verbose;
957 #ifdef INET6
958 	int af = AF_UNSPEC;
959 #else
960 	int af = AF_INET;
961 #endif
962 
963 	direct = CHECK_FLAG('d');
964 	verbose = CHECK_FLAG('v');
965 	if (CHECK_FLAG('4'))
966 		af = AF_INET;
967 	else if (CHECK_FLAG('6'))
968 		af = AF_INET6;
969 
970 	if (direct)
971 		purl = NULL;
972 
973 	/* check for proxy */
974 	if (purl) {
975 		/* XXX proxy authentication! */
976 		conn = fetch_connect(purl->host, purl->port, af, verbose);
977 	} else {
978 		/* no proxy, go straight to target */
979 		conn = fetch_connect(url->host, url->port, af, verbose);
980 		purl = NULL;
981 	}
982 
983 	/* check connection */
984 	if (conn == NULL)
985 		/* fetch_connect() has already set an error code */
986 		return (NULL);
987 
988 	/* expect welcome message */
989 	if ((e = ftp_chkerr(conn)) != FTP_SERVICE_READY)
990 		goto fouch;
991 
992 	/* authenticate */
993 	if ((e = ftp_authenticate(conn, url, purl)) != FTP_LOGGED_IN)
994 		goto fouch;
995 
996 	/* TODO: Request extended features supported, if any (RFC 3659). */
997 
998 	/* done */
999 	return (conn);
1000 
1001 fouch:
1002 	if (e != -1)
1003 		ftp_seterr(e);
1004 	fetch_close(conn);
1005 	return (NULL);
1006 }
1007 
1008 /*
1009  * Disconnect from server
1010  */
1011 static void
1012 ftp_disconnect(conn_t *conn)
1013 {
1014 	(void)ftp_cmd(conn, "QUIT");
1015 	if (conn == cached_connection && conn->ref == 1)
1016 		cached_connection = NULL;
1017 	fetch_close(conn);
1018 }
1019 
1020 /*
1021  * Check if we're already connected
1022  */
1023 static int
1024 ftp_isconnected(struct url *url)
1025 {
1026 	return (cached_connection
1027 	    && (strcmp(url->host, cached_host.host) == 0)
1028 	    && (strcmp(url->user, cached_host.user) == 0)
1029 	    && (strcmp(url->pwd, cached_host.pwd) == 0)
1030 	    && (url->port == cached_host.port));
1031 }
1032 
1033 /*
1034  * Check the cache, reconnect if no luck
1035  */
1036 static conn_t *
1037 ftp_cached_connect(struct url *url, struct url *purl, const char *flags)
1038 {
1039 	conn_t *conn;
1040 	int e;
1041 
1042 	/* set default port */
1043 	if (!url->port)
1044 		url->port = fetch_default_port(url->scheme);
1045 
1046 	/* try to use previously cached connection */
1047 	if (ftp_isconnected(url)) {
1048 		e = ftp_cmd(cached_connection, "NOOP");
1049 		if (e == FTP_OK || e == FTP_SYNTAX_ERROR)
1050 			return (fetch_ref(cached_connection));
1051 	}
1052 
1053 	/* connect to server */
1054 	if ((conn = ftp_connect(url, purl, flags)) == NULL)
1055 		return (NULL);
1056 	if (cached_connection)
1057 		ftp_disconnect(cached_connection);
1058 	cached_connection = fetch_ref(conn);
1059 	memcpy(&cached_host, url, sizeof(*url));
1060 	return (conn);
1061 }
1062 
1063 /*
1064  * Check the proxy settings
1065  */
1066 static struct url *
1067 ftp_get_proxy(struct url * url, const char *flags)
1068 {
1069 	struct url *purl;
1070 	char *p;
1071 
1072 	if (flags != NULL && strchr(flags, 'd') != NULL)
1073 		return (NULL);
1074 	if (fetch_no_proxy_match(url->host))
1075 		return (NULL);
1076 	if (((p = getenv("FTP_PROXY")) || (p = getenv("ftp_proxy")) ||
1077 		(p = getenv("HTTP_PROXY")) || (p = getenv("http_proxy"))) &&
1078 	    *p && (purl = fetchParseURL(p)) != NULL) {
1079 		if (!*purl->scheme) {
1080 			if (getenv("FTP_PROXY") || getenv("ftp_proxy"))
1081 				strcpy(purl->scheme, SCHEME_FTP);
1082 			else
1083 				strcpy(purl->scheme, SCHEME_HTTP);
1084 		}
1085 		if (!purl->port)
1086 			purl->port = fetch_default_proxy_port(purl->scheme);
1087 		if (strcmp(purl->scheme, SCHEME_FTP) == 0 ||
1088 		    strcmp(purl->scheme, SCHEME_HTTP) == 0)
1089 			return (purl);
1090 		fetchFreeURL(purl);
1091 	}
1092 	return (NULL);
1093 }
1094 
1095 /*
1096  * Process an FTP request
1097  */
1098 FILE *
1099 ftp_request(struct url *url, const char *op, struct url_stat *us,
1100     struct url *purl, const char *flags)
1101 {
1102 	conn_t *conn;
1103 	int oflag;
1104 
1105 	/* check if we should use HTTP instead */
1106 	if (purl && (strcmp(purl->scheme, SCHEME_HTTP) == 0 ||
1107 	    strcmp(purl->scheme, SCHEME_HTTPS) == 0)) {
1108 		if (strcmp(op, "STAT") == 0)
1109 			return (http_request(url, "HEAD", us, purl, flags));
1110 		else if (strcmp(op, "RETR") == 0)
1111 			return (http_request(url, "GET", us, purl, flags));
1112 		/*
1113 		 * Our HTTP code doesn't support PUT requests yet, so try
1114 		 * a direct connection.
1115 		 */
1116 	}
1117 
1118 	/* connect to server */
1119 	conn = ftp_cached_connect(url, purl, flags);
1120 	if (purl)
1121 		fetchFreeURL(purl);
1122 	if (conn == NULL)
1123 		return (NULL);
1124 
1125 	/* change directory */
1126 	if (ftp_cwd(conn, url->doc) == -1)
1127 		goto errsock;
1128 
1129 	/* stat file */
1130 	if (us && ftp_stat(conn, url->doc, us) == -1
1131 	    && fetchLastErrCode != FETCH_PROTO
1132 	    && fetchLastErrCode != FETCH_UNAVAIL)
1133 		goto errsock;
1134 
1135 	/* just a stat */
1136 	if (strcmp(op, "STAT") == 0) {
1137 		fetch_deref(conn);
1138 		ftp_disconnect(conn);
1139 		return (FILE *)1; /* bogus return value */
1140 	}
1141 	if (strcmp(op, "STOR") == 0 || strcmp(op, "APPE") == 0)
1142 		oflag = O_WRONLY;
1143 	else
1144 		oflag = O_RDONLY;
1145 
1146 	/* initiate the transfer */
1147 	return (ftp_transfer(conn, op, url->doc, oflag, url->offset, flags));
1148 
1149 errsock:
1150 	ftp_disconnect(conn);
1151 	return (NULL);
1152 }
1153 
1154 /*
1155  * Get and stat file
1156  */
1157 FILE *
1158 fetchXGetFTP(struct url *url, struct url_stat *us, const char *flags)
1159 {
1160 	return (ftp_request(url, "RETR", us, ftp_get_proxy(url, flags), flags));
1161 }
1162 
1163 /*
1164  * Get file
1165  */
1166 FILE *
1167 fetchGetFTP(struct url *url, const char *flags)
1168 {
1169 	return (fetchXGetFTP(url, NULL, flags));
1170 }
1171 
1172 /*
1173  * Put file
1174  */
1175 FILE *
1176 fetchPutFTP(struct url *url, const char *flags)
1177 {
1178 	return (ftp_request(url, CHECK_FLAG('a') ? "APPE" : "STOR", NULL,
1179 	    ftp_get_proxy(url, flags), flags));
1180 }
1181 
1182 /*
1183  * Get file stats
1184  */
1185 int
1186 fetchStatFTP(struct url *url, struct url_stat *us, const char *flags)
1187 {
1188 	FILE *f;
1189 
1190 	f = ftp_request(url, "STAT", us, ftp_get_proxy(url, flags), flags);
1191 	if (f == NULL)
1192 		return (-1);
1193 	/*
1194 	 * When op is "STAT", ftp_request() will return either NULL or
1195 	 * (FILE *)1, never a valid FILE *, so we mustn't fclose(f) before
1196 	 * returning, as it would cause a segfault.
1197 	 */
1198 	return (0);
1199 }
1200 
1201 /*
1202  * List a directory
1203  */
1204 struct url_ent *
1205 fetchListFTP(struct url *url __unused, const char *flags __unused)
1206 {
1207 	warnx("fetchListFTP(): not implemented");
1208 	return (NULL);
1209 }
1210