xref: /freebsd/lib/libfetch/ftp.c (revision 702c24ccc0c208e9bc697e775abe47ff723e3012)
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 	if (isftpinfo(conn->buf)) {
152 		while (conn->buflen && !isftpreply(conn->buf)) {
153 			if ((rlen = fetch_getln(conn)) < 0) {
154 				fetch_syserr();
155 				return (-1);
156 			}
157 		}
158 	}
159 
160 	if (!isftpreply(conn->buf)) {
161 		ftp_seterr(FTP_PROTOCOL_ERROR);
162 		return (-1);
163 	}
164 
165 	conn->err = (conn->buf[0] - '0') * 100
166 	    + (conn->buf[1] - '0') * 10
167 	    + (conn->buf[2] - '0');
168 
169 	return (conn->err);
170 }
171 
172 /*
173  * Send a command and check reply
174  */
175 static int
176 ftp_cmd(conn_t *conn, const char *fmt, ...)
177 {
178 	va_list ap;
179 	size_t len;
180 	char *msg;
181 	int r;
182 
183 	va_start(ap, fmt);
184 	len = vasprintf(&msg, fmt, ap);
185 	va_end(ap);
186 
187 	if (msg == NULL) {
188 		errno = ENOMEM;
189 		fetch_syserr();
190 		return (-1);
191 	}
192 
193 	r = fetch_putln(conn, msg, len);
194 	free(msg);
195 
196 	if (r == -1) {
197 		fetch_syserr();
198 		return (-1);
199 	}
200 
201 	return (ftp_chkerr(conn));
202 }
203 
204 /*
205  * Return a pointer to the filename part of a path
206  */
207 static const char *
208 ftp_filename(const char *file, int *len, int *type)
209 {
210 	const char *s;
211 
212 	if ((s = strrchr(file, '/')) == NULL)
213 		s = file;
214 	else
215 		s = s + 1;
216 	*len = strlen(s);
217 	if (*len > 7 && strncmp(s + *len - 7, ";type=", 6) == 0) {
218 		*type = s[*len - 1];
219 		*len -= 7;
220 	} else {
221 		*type = '\0';
222 	}
223 	return (s);
224 }
225 
226 /*
227  * Get current working directory from the reply to a CWD, PWD or CDUP
228  * command.
229  */
230 static int
231 ftp_pwd(conn_t *conn, char *pwd, size_t pwdlen)
232 {
233 	char *src, *dst, *end;
234 	int q;
235 
236 	if (conn->err != FTP_WORKING_DIRECTORY &&
237 	    conn->err != FTP_FILE_ACTION_OK)
238 		return (FTP_PROTOCOL_ERROR);
239 	end = conn->buf + conn->buflen;
240 	src = conn->buf + 4;
241 	if (src >= end || *src++ != '"')
242 		return (FTP_PROTOCOL_ERROR);
243 	for (q = 0, dst = pwd; src < end && pwdlen--; ++src) {
244 		if (!q && *src == '"')
245 			q = 1;
246 		else if (q && *src != '"')
247 			break;
248 		else if (q)
249 			*dst++ = '"', q = 0;
250 		else
251 			*dst++ = *src;
252 	}
253 	if (!pwdlen)
254 		return (FTP_PROTOCOL_ERROR);
255 	*dst = '\0';
256 #if 0
257 	DEBUGF("pwd: [%s]\n", pwd);
258 #endif
259 	return (FTP_OK);
260 }
261 
262 /*
263  * Change working directory to the directory that contains the specified
264  * file.
265  */
266 static int
267 ftp_cwd(conn_t *conn, const char *file)
268 {
269 	const char *beg, *end;
270 	char pwd[PATH_MAX];
271 	int e, i, len;
272 
273 	/* If no slashes in name, no need to change dirs. */
274 	if ((end = strrchr(file, '/')) == NULL)
275 		return (0);
276 	if ((e = ftp_cmd(conn, "PWD")) != FTP_WORKING_DIRECTORY ||
277 	    (e = ftp_pwd(conn, pwd, sizeof(pwd))) != FTP_OK) {
278 		ftp_seterr(e);
279 		return (-1);
280 	}
281 	for (;;) {
282 		len = strlen(pwd);
283 
284 		/* Look for a common prefix between PWD and dir to fetch. */
285 		for (i = 0; i <= len && i <= end - file; ++i)
286 			if (pwd[i] != file[i])
287 				break;
288 #if 0
289 		DEBUGF("have: [%.*s|%s]\n", i, pwd, pwd + i);
290 		DEBUGF("want: [%.*s|%s]\n", i, file, file + i);
291 #endif
292 		/* Keep going up a dir until we have a matching prefix. */
293 		if (pwd[i] == '\0' && (file[i - 1] == '/' || file[i] == '/'))
294 			break;
295 		if ((e = ftp_cmd(conn, "CDUP")) != FTP_FILE_ACTION_OK ||
296 		    (e = ftp_cmd(conn, "PWD")) != FTP_WORKING_DIRECTORY ||
297 		    (e = ftp_pwd(conn, pwd, sizeof(pwd))) != FTP_OK) {
298 			ftp_seterr(e);
299 			return (-1);
300 		}
301 	}
302 
303 #ifdef FTP_COMBINE_CWDS
304 	/* Skip leading slashes, even "////". */
305 	for (beg = file + i; beg < end && *beg == '/'; ++beg, ++i)
306 		/* nothing */ ;
307 
308 	/* If there is no trailing dir, we're already there. */
309 	if (beg >= end)
310 		return (0);
311 
312 	/* Change to the directory all in one chunk (e.g., foo/bar/baz). */
313 	e = ftp_cmd(conn, "CWD %.*s", (int)(end - beg), beg);
314 	if (e == FTP_FILE_ACTION_OK)
315 		return (0);
316 #endif /* FTP_COMBINE_CWDS */
317 
318 	/* That didn't work so go back to legacy behavior (multiple CWDs). */
319 	for (beg = file + i; beg < end; beg = file + i + 1) {
320 		while (*beg == '/')
321 			++beg, ++i;
322 		for (++i; file + i < end && file[i] != '/'; ++i)
323 			/* nothing */ ;
324 		e = ftp_cmd(conn, "CWD %.*s", file + i - beg, beg);
325 		if (e != FTP_FILE_ACTION_OK) {
326 			ftp_seterr(e);
327 			return (-1);
328 		}
329 	}
330 	return (0);
331 }
332 
333 /*
334  * Set transfer mode and data type
335  */
336 static int
337 ftp_mode_type(conn_t *conn, int mode, int type)
338 {
339 	int e;
340 
341 	switch (mode) {
342 	case 0:
343 	case 's':
344 		mode = 'S';
345 	case 'S':
346 		break;
347 	default:
348 		return (FTP_PROTOCOL_ERROR);
349 	}
350 	if ((e = ftp_cmd(conn, "MODE %c", mode)) != FTP_OK) {
351 		if (mode == 'S') {
352 			/*
353 			 * Stream mode is supposed to be the default - so
354 			 * much so that some servers not only do not
355 			 * support any other mode, but do not support the
356 			 * MODE command at all.
357 			 *
358 			 * If "MODE S" fails, it is unlikely that we
359 			 * previously succeeded in setting a different
360 			 * mode.  Therefore, we simply hope that the
361 			 * server is already in the correct mode, and
362 			 * silently ignore the failure.
363 			 */
364 		} else {
365 			return (e);
366 		}
367 	}
368 
369 	switch (type) {
370 	case 0:
371 	case 'i':
372 		type = 'I';
373 	case 'I':
374 		break;
375 	case 'a':
376 		type = 'A';
377 	case 'A':
378 		break;
379 	case 'd':
380 		type = 'D';
381 	case 'D':
382 		/* can't handle yet */
383 	default:
384 		return (FTP_PROTOCOL_ERROR);
385 	}
386 	if ((e = ftp_cmd(conn, "TYPE %c", type)) != FTP_OK)
387 		return (e);
388 
389 	return (FTP_OK);
390 }
391 
392 /*
393  * Request and parse file stats
394  */
395 static int
396 ftp_stat(conn_t *conn, const char *file, struct url_stat *us)
397 {
398 	char *ln;
399 	const char *filename;
400 	int filenamelen, type;
401 	struct tm tm;
402 	time_t t;
403 	int e;
404 
405 	us->size = -1;
406 	us->atime = us->mtime = 0;
407 
408 	filename = ftp_filename(file, &filenamelen, &type);
409 
410 	if ((e = ftp_mode_type(conn, 0, type)) != FTP_OK) {
411 		ftp_seterr(e);
412 		return (-1);
413 	}
414 
415 	e = ftp_cmd(conn, "SIZE %.*s", filenamelen, filename);
416 	if (e != FTP_FILE_STATUS) {
417 		ftp_seterr(e);
418 		return (-1);
419 	}
420 	for (ln = conn->buf + 4; *ln && isspace((unsigned char)*ln); ln++)
421 		/* nothing */ ;
422 	for (us->size = 0; *ln && isdigit((unsigned char)*ln); ln++)
423 		us->size = us->size * 10 + *ln - '0';
424 	if (*ln && !isspace((unsigned char)*ln)) {
425 		ftp_seterr(FTP_PROTOCOL_ERROR);
426 		us->size = -1;
427 		return (-1);
428 	}
429 	if (us->size == 0)
430 		us->size = -1;
431 	DEBUGF("size: [%lld]\n", (long long)us->size);
432 
433 	e = ftp_cmd(conn, "MDTM %.*s", filenamelen, filename);
434 	if (e != FTP_FILE_STATUS) {
435 		ftp_seterr(e);
436 		return (-1);
437 	}
438 	for (ln = conn->buf + 4; *ln && isspace((unsigned char)*ln); ln++)
439 		/* nothing */ ;
440 	switch (strspn(ln, "0123456789")) {
441 	case 14:
442 		break;
443 	case 15:
444 		ln++;
445 		ln[0] = '2';
446 		ln[1] = '0';
447 		break;
448 	default:
449 		ftp_seterr(FTP_PROTOCOL_ERROR);
450 		return (-1);
451 	}
452 	if (sscanf(ln, "%04d%02d%02d%02d%02d%02d",
453 	    &tm.tm_year, &tm.tm_mon, &tm.tm_mday,
454 	    &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
455 		ftp_seterr(FTP_PROTOCOL_ERROR);
456 		return (-1);
457 	}
458 	tm.tm_mon--;
459 	tm.tm_year -= 1900;
460 	tm.tm_isdst = -1;
461 	t = timegm(&tm);
462 	if (t == (time_t)-1)
463 		t = time(NULL);
464 	us->mtime = t;
465 	us->atime = t;
466 	DEBUGF("last modified: [%04d-%02d-%02d %02d:%02d:%02d]\n",
467 	    tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
468 	    tm.tm_hour, tm.tm_min, tm.tm_sec);
469 	return (0);
470 }
471 
472 /*
473  * I/O functions for FTP
474  */
475 struct ftpio {
476 	conn_t	*cconn;		/* Control connection */
477 	conn_t	*dconn;		/* Data connection */
478 	int	 dir;		/* Direction */
479 	int	 eof;		/* EOF reached */
480 	int	 err;		/* Error code */
481 };
482 
483 static int	 ftp_readfn(void *, char *, int);
484 static int	 ftp_writefn(void *, const char *, int);
485 static fpos_t	 ftp_seekfn(void *, fpos_t, int);
486 static int	 ftp_closefn(void *);
487 
488 static int
489 ftp_readfn(void *v, char *buf, int len)
490 {
491 	struct ftpio *io;
492 	int r;
493 
494 	io = (struct ftpio *)v;
495 	if (io == NULL) {
496 		errno = EBADF;
497 		return (-1);
498 	}
499 	if (io->cconn == NULL || io->dconn == NULL || io->dir == O_WRONLY) {
500 		errno = EBADF;
501 		return (-1);
502 	}
503 	if (io->err) {
504 		errno = io->err;
505 		return (-1);
506 	}
507 	if (io->eof)
508 		return (0);
509 	r = fetch_read(io->dconn, buf, len);
510 	if (r > 0)
511 		return (r);
512 	if (r == 0) {
513 		io->eof = 1;
514 		return (0);
515 	}
516 	if (errno != EINTR)
517 		io->err = errno;
518 	return (-1);
519 }
520 
521 static int
522 ftp_writefn(void *v, const char *buf, int len)
523 {
524 	struct ftpio *io;
525 	int w;
526 
527 	io = (struct ftpio *)v;
528 	if (io == NULL) {
529 		errno = EBADF;
530 		return (-1);
531 	}
532 	if (io->cconn == NULL || io->dconn == NULL || io->dir == O_RDONLY) {
533 		errno = EBADF;
534 		return (-1);
535 	}
536 	if (io->err) {
537 		errno = io->err;
538 		return (-1);
539 	}
540 	w = fetch_write(io->dconn, buf, len);
541 	if (w >= 0)
542 		return (w);
543 	if (errno != EINTR)
544 		io->err = errno;
545 	return (-1);
546 }
547 
548 static fpos_t
549 ftp_seekfn(void *v, fpos_t pos __unused, int whence __unused)
550 {
551 	struct ftpio *io;
552 
553 	io = (struct ftpio *)v;
554 	if (io == NULL) {
555 		errno = EBADF;
556 		return (-1);
557 	}
558 	errno = ESPIPE;
559 	return (-1);
560 }
561 
562 static int
563 ftp_closefn(void *v)
564 {
565 	struct ftpio *io;
566 	int r;
567 
568 	io = (struct ftpio *)v;
569 	if (io == NULL) {
570 		errno = EBADF;
571 		return (-1);
572 	}
573 	if (io->dir == -1)
574 		return (0);
575 	if (io->cconn == NULL || io->dconn == NULL) {
576 		errno = EBADF;
577 		return (-1);
578 	}
579 	fetch_close(io->dconn);
580 	io->dir = -1;
581 	io->dconn = NULL;
582 	DEBUGF("Waiting for final status\n");
583 	r = ftp_chkerr(io->cconn);
584 	if (io->cconn == cached_connection && io->cconn->ref == 1)
585 		cached_connection = NULL;
586 	fetch_close(io->cconn);
587 	free(io);
588 	return (r == FTP_TRANSFER_COMPLETE) ? 0 : -1;
589 }
590 
591 static FILE *
592 ftp_setup(conn_t *cconn, conn_t *dconn, int mode)
593 {
594 	struct ftpio *io;
595 	FILE *f;
596 
597 	if (cconn == NULL || dconn == NULL)
598 		return (NULL);
599 	if ((io = malloc(sizeof(*io))) == NULL)
600 		return (NULL);
601 	io->cconn = cconn;
602 	io->dconn = dconn;
603 	io->dir = mode;
604 	io->eof = io->err = 0;
605 	f = funopen(io, ftp_readfn, ftp_writefn, ftp_seekfn, ftp_closefn);
606 	if (f == NULL)
607 		free(io);
608 	return (f);
609 }
610 
611 /*
612  * Transfer file
613  */
614 static FILE *
615 ftp_transfer(conn_t *conn, const char *oper, const char *file,
616     int mode, off_t offset, const char *flags)
617 {
618 	struct sockaddr_storage sa;
619 	struct sockaddr_in6 *sin6;
620 	struct sockaddr_in *sin4;
621 	const char *bindaddr;
622 	const char *filename;
623 	int filenamelen, type;
624 	int low, pasv, verbose;
625 	int e, sd = -1;
626 	socklen_t l;
627 	char *s;
628 	FILE *df;
629 
630 	/* check flags */
631 	low = CHECK_FLAG('l');
632 	pasv = CHECK_FLAG('p') || !CHECK_FLAG('P');
633 	verbose = CHECK_FLAG('v');
634 
635 	/* passive mode */
636 	if ((s = getenv("FTP_PASSIVE_MODE")) != NULL)
637 		pasv = (strncasecmp(s, "no", 2) != 0);
638 
639 	/* isolate filename */
640 	filename = ftp_filename(file, &filenamelen, &type);
641 
642 	/* set transfer mode and data type */
643 	if ((e = ftp_mode_type(conn, 0, type)) != FTP_OK)
644 		goto ouch;
645 
646 	/* find our own address, bind, and listen */
647 	l = sizeof(sa);
648 	if (getsockname(conn->sd, (struct sockaddr *)&sa, &l) == -1)
649 		goto sysouch;
650 	if (sa.ss_family == AF_INET6)
651 		unmappedaddr((struct sockaddr_in6 *)&sa);
652 
653 	/* open data socket */
654 	if ((sd = socket(sa.ss_family, SOCK_STREAM, IPPROTO_TCP)) == -1) {
655 		fetch_syserr();
656 		return (NULL);
657 	}
658 
659 	if (pasv) {
660 		u_char addr[64];
661 		char *ln, *p;
662 		unsigned int i;
663 		int port;
664 
665 		/* send PASV command */
666 		if (verbose)
667 			fetch_info("setting passive mode");
668 		switch (sa.ss_family) {
669 		case AF_INET:
670 			if ((e = ftp_cmd(conn, "PASV")) != FTP_PASSIVE_MODE)
671 				goto ouch;
672 			break;
673 		case AF_INET6:
674 			if ((e = ftp_cmd(conn, "EPSV")) != FTP_EPASSIVE_MODE) {
675 				if (e == -1)
676 					goto ouch;
677 				if ((e = ftp_cmd(conn, "LPSV")) !=
678 				    FTP_LPASSIVE_MODE)
679 					goto ouch;
680 			}
681 			break;
682 		default:
683 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
684 			goto ouch;
685 		}
686 
687 		/*
688 		 * Find address and port number. The reply to the PASV command
689 		 * is IMHO the one and only weak point in the FTP protocol.
690 		 */
691 		ln = conn->buf;
692 		switch (e) {
693 		case FTP_PASSIVE_MODE:
694 		case FTP_LPASSIVE_MODE:
695 			for (p = ln + 3; *p && !isdigit((unsigned char)*p); p++)
696 				/* nothing */ ;
697 			if (!*p) {
698 				e = FTP_PROTOCOL_ERROR;
699 				goto ouch;
700 			}
701 			l = (e == FTP_PASSIVE_MODE ? 6 : 21);
702 			for (i = 0; *p && i < l; i++, p++) {
703 				addr[i] = strtol(p, &p, 10);
704 				if (*p == '\0' && i < l - 1)
705 					break;
706 			}
707 			if (i < l) {
708 				e = FTP_PROTOCOL_ERROR;
709 				goto ouch;
710 			}
711 			break;
712 		case FTP_EPASSIVE_MODE:
713 			for (p = ln + 3; *p && *p != '('; p++)
714 				/* nothing */ ;
715 			if (!*p) {
716 				e = FTP_PROTOCOL_ERROR;
717 				goto ouch;
718 			}
719 			++p;
720 			if (sscanf(p, "%c%c%c%d%c", &addr[0], &addr[1], &addr[2],
721 				&port, &addr[3]) != 5 ||
722 			    addr[0] != addr[1] ||
723 			    addr[0] != addr[2] || addr[0] != addr[3]) {
724 				e = FTP_PROTOCOL_ERROR;
725 				goto ouch;
726 			}
727 			break;
728 		}
729 
730 		/* seek to required offset */
731 		if (offset)
732 			if (ftp_cmd(conn, "REST %lu", (u_long)offset) != FTP_FILE_OK)
733 				goto sysouch;
734 
735 		/* construct sockaddr for data socket */
736 		l = sizeof(sa);
737 		if (getpeername(conn->sd, (struct sockaddr *)&sa, &l) == -1)
738 			goto sysouch;
739 		if (sa.ss_family == AF_INET6)
740 			unmappedaddr((struct sockaddr_in6 *)&sa);
741 		switch (sa.ss_family) {
742 		case AF_INET6:
743 			sin6 = (struct sockaddr_in6 *)&sa;
744 			if (e == FTP_EPASSIVE_MODE)
745 				sin6->sin6_port = htons(port);
746 			else {
747 				memcpy(&sin6->sin6_addr, addr + 2, 16);
748 				memcpy(&sin6->sin6_port, addr + 19, 2);
749 			}
750 			break;
751 		case AF_INET:
752 			sin4 = (struct sockaddr_in *)&sa;
753 			if (e == FTP_EPASSIVE_MODE)
754 				sin4->sin_port = htons(port);
755 			else {
756 				memcpy(&sin4->sin_addr, addr, 4);
757 				memcpy(&sin4->sin_port, addr + 4, 2);
758 			}
759 			break;
760 		default:
761 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
762 			break;
763 		}
764 
765 		/* connect to data port */
766 		if (verbose)
767 			fetch_info("opening data connection");
768 		bindaddr = getenv("FETCH_BIND_ADDRESS");
769 		if (bindaddr != NULL && *bindaddr != '\0' &&
770 		    (e = fetch_bind(sd, sa.ss_family, bindaddr)) != 0)
771 			goto ouch;
772 		if (connect(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
773 			goto sysouch;
774 
775 		/* make the server initiate the transfer */
776 		if (verbose)
777 			fetch_info("initiating transfer");
778 		e = ftp_cmd(conn, "%s %.*s", oper, filenamelen, filename);
779 		if (e != FTP_CONNECTION_ALREADY_OPEN && e != FTP_OPEN_DATA_CONNECTION)
780 			goto ouch;
781 
782 	} else {
783 		u_int32_t a;
784 		u_short p;
785 		int arg, d;
786 		char *ap;
787 		char hname[INET6_ADDRSTRLEN];
788 
789 		switch (sa.ss_family) {
790 		case AF_INET6:
791 			((struct sockaddr_in6 *)&sa)->sin6_port = 0;
792 #ifdef IPV6_PORTRANGE
793 			arg = low ? IPV6_PORTRANGE_DEFAULT : IPV6_PORTRANGE_HIGH;
794 			if (setsockopt(sd, IPPROTO_IPV6, IPV6_PORTRANGE,
795 				(char *)&arg, sizeof(arg)) == -1)
796 				goto sysouch;
797 #endif
798 			break;
799 		case AF_INET:
800 			((struct sockaddr_in *)&sa)->sin_port = 0;
801 			arg = low ? IP_PORTRANGE_DEFAULT : IP_PORTRANGE_HIGH;
802 			if (setsockopt(sd, IPPROTO_IP, IP_PORTRANGE,
803 				(char *)&arg, sizeof(arg)) == -1)
804 				goto sysouch;
805 			break;
806 		}
807 		if (verbose)
808 			fetch_info("binding data socket");
809 		if (bind(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
810 			goto sysouch;
811 		if (listen(sd, 1) == -1)
812 			goto sysouch;
813 
814 		/* find what port we're on and tell the server */
815 		if (getsockname(sd, (struct sockaddr *)&sa, &l) == -1)
816 			goto sysouch;
817 		switch (sa.ss_family) {
818 		case AF_INET:
819 			sin4 = (struct sockaddr_in *)&sa;
820 			a = ntohl(sin4->sin_addr.s_addr);
821 			p = ntohs(sin4->sin_port);
822 			e = ftp_cmd(conn, "PORT %d,%d,%d,%d,%d,%d",
823 			    (a >> 24) & 0xff, (a >> 16) & 0xff,
824 			    (a >> 8) & 0xff, a & 0xff,
825 			    (p >> 8) & 0xff, p & 0xff);
826 			break;
827 		case AF_INET6:
828 #define UC(b)	(((int)b)&0xff)
829 			e = -1;
830 			sin6 = (struct sockaddr_in6 *)&sa;
831 			sin6->sin6_scope_id = 0;
832 			if (getnameinfo((struct sockaddr *)&sa, sa.ss_len,
833 				hname, sizeof(hname),
834 				NULL, 0, NI_NUMERICHOST) == 0) {
835 				e = ftp_cmd(conn, "EPRT |%d|%s|%d|", 2, hname,
836 				    htons(sin6->sin6_port));
837 				if (e == -1)
838 					goto ouch;
839 			}
840 			if (e != FTP_OK) {
841 				ap = (char *)&sin6->sin6_addr;
842 				e = ftp_cmd(conn,
843 				    "LPRT %d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",
844 				    6, 16,
845 				    UC(ap[0]), UC(ap[1]), UC(ap[2]), UC(ap[3]),
846 				    UC(ap[4]), UC(ap[5]), UC(ap[6]), UC(ap[7]),
847 				    UC(ap[8]), UC(ap[9]), UC(ap[10]), UC(ap[11]),
848 				    UC(ap[12]), UC(ap[13]), UC(ap[14]), UC(ap[15]),
849 				    2,
850 				    (ntohs(sin6->sin6_port) >> 8) & 0xff,
851 				    ntohs(sin6->sin6_port)        & 0xff);
852 			}
853 			break;
854 		default:
855 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
856 			goto ouch;
857 		}
858 		if (e != FTP_OK)
859 			goto ouch;
860 
861 		/* seek to required offset */
862 		if (offset)
863 			if (ftp_cmd(conn, "REST %ju", (uintmax_t)offset) != FTP_FILE_OK)
864 				goto sysouch;
865 
866 		/* make the server initiate the transfer */
867 		if (verbose)
868 			fetch_info("initiating transfer");
869 		e = ftp_cmd(conn, "%s %.*s", oper, filenamelen, filename);
870 		if (e != FTP_CONNECTION_ALREADY_OPEN && e != FTP_OPEN_DATA_CONNECTION)
871 			goto ouch;
872 
873 		/* accept the incoming connection and go to town */
874 		if ((d = accept(sd, NULL, NULL)) == -1)
875 			goto sysouch;
876 		close(sd);
877 		sd = d;
878 	}
879 
880 	if ((df = ftp_setup(conn, fetch_reopen(sd), mode)) == NULL)
881 		goto sysouch;
882 	return (df);
883 
884 sysouch:
885 	fetch_syserr();
886 	if (sd >= 0)
887 		close(sd);
888 	return (NULL);
889 
890 ouch:
891 	if (e != -1)
892 		ftp_seterr(e);
893 	if (sd >= 0)
894 		close(sd);
895 	return (NULL);
896 }
897 
898 /*
899  * Authenticate
900  */
901 static int
902 ftp_authenticate(conn_t *conn, struct url *url, struct url *purl)
903 {
904 	const char *user, *pwd, *logname;
905 	char pbuf[MAXHOSTNAMELEN + MAXLOGNAME + 1];
906 	int e, len;
907 
908 	/* XXX FTP_AUTH, and maybe .netrc */
909 
910 	/* send user name and password */
911 	if (url->user[0] == '\0')
912 		fetch_netrc_auth(url);
913 	user = url->user;
914 	if (*user == '\0')
915 		if ((user = getenv("FTP_LOGIN")) != NULL)
916 			DEBUGF("FTP_LOGIN=%s\n", user);
917 	if (user == NULL || *user == '\0')
918 		user = FTP_ANONYMOUS_USER;
919 	if (purl && url->port == fetch_default_port(url->scheme))
920 		e = ftp_cmd(conn, "USER %s@%s", user, url->host);
921 	else if (purl)
922 		e = ftp_cmd(conn, "USER %s@%s@%d", user, url->host, url->port);
923 	else
924 		e = ftp_cmd(conn, "USER %s", user);
925 
926 	/* did the server request a password? */
927 	if (e == FTP_NEED_PASSWORD) {
928 		pwd = url->pwd;
929 		if (*pwd == '\0')
930 			if ((pwd = getenv("FTP_PASSWORD")) != NULL)
931 				DEBUGF("FTP_PASSWORD=%s\n", pwd);
932 		if (pwd == NULL || *pwd == '\0') {
933 			if ((logname = getlogin()) == NULL)
934 				logname = FTP_ANONYMOUS_USER;
935 			if ((len = snprintf(pbuf, MAXLOGNAME + 1, "%s@", logname)) < 0)
936 				len = 0;
937 			else if (len > MAXLOGNAME)
938 				len = MAXLOGNAME;
939 			gethostname(pbuf + len, sizeof(pbuf) - len);
940 			pwd = pbuf;
941 		}
942 		e = ftp_cmd(conn, "PASS %s", pwd);
943 	}
944 
945 	return (e);
946 }
947 
948 /*
949  * Log on to FTP server
950  */
951 static conn_t *
952 ftp_connect(struct url *url, struct url *purl, const char *flags)
953 {
954 	conn_t *conn;
955 	int e, direct, verbose;
956 #ifdef INET6
957 	int af = AF_UNSPEC;
958 #else
959 	int af = AF_INET;
960 #endif
961 
962 	direct = CHECK_FLAG('d');
963 	verbose = CHECK_FLAG('v');
964 	if (CHECK_FLAG('4'))
965 		af = AF_INET;
966 	else if (CHECK_FLAG('6'))
967 		af = AF_INET6;
968 
969 	if (direct)
970 		purl = NULL;
971 
972 	/* check for proxy */
973 	if (purl) {
974 		/* XXX proxy authentication! */
975 		conn = fetch_connect(purl->host, purl->port, af, verbose);
976 	} else {
977 		/* no proxy, go straight to target */
978 		conn = fetch_connect(url->host, url->port, af, verbose);
979 		purl = NULL;
980 	}
981 
982 	/* check connection */
983 	if (conn == NULL)
984 		/* fetch_connect() has already set an error code */
985 		return (NULL);
986 
987 	/* expect welcome message */
988 	if ((e = ftp_chkerr(conn)) != FTP_SERVICE_READY)
989 		goto fouch;
990 
991 	/* authenticate */
992 	if ((e = ftp_authenticate(conn, url, purl)) != FTP_LOGGED_IN)
993 		goto fouch;
994 
995 	/* TODO: Request extended features supported, if any (RFC 3659). */
996 
997 	/* done */
998 	return (conn);
999 
1000 fouch:
1001 	if (e != -1)
1002 		ftp_seterr(e);
1003 	fetch_close(conn);
1004 	return (NULL);
1005 }
1006 
1007 /*
1008  * Disconnect from server
1009  */
1010 static void
1011 ftp_disconnect(conn_t *conn)
1012 {
1013 	(void)ftp_cmd(conn, "QUIT");
1014 	if (conn == cached_connection && conn->ref == 1)
1015 		cached_connection = NULL;
1016 	fetch_close(conn);
1017 }
1018 
1019 /*
1020  * Check if we're already connected
1021  */
1022 static int
1023 ftp_isconnected(struct url *url)
1024 {
1025 	return (cached_connection
1026 	    && (strcmp(url->host, cached_host.host) == 0)
1027 	    && (strcmp(url->user, cached_host.user) == 0)
1028 	    && (strcmp(url->pwd, cached_host.pwd) == 0)
1029 	    && (url->port == cached_host.port));
1030 }
1031 
1032 /*
1033  * Check the cache, reconnect if no luck
1034  */
1035 static conn_t *
1036 ftp_cached_connect(struct url *url, struct url *purl, const char *flags)
1037 {
1038 	conn_t *conn;
1039 	int e;
1040 
1041 	/* set default port */
1042 	if (!url->port)
1043 		url->port = fetch_default_port(url->scheme);
1044 
1045 	/* try to use previously cached connection */
1046 	if (ftp_isconnected(url)) {
1047 		e = ftp_cmd(cached_connection, "NOOP");
1048 		if (e == FTP_OK || e == FTP_SYNTAX_ERROR)
1049 			return (fetch_ref(cached_connection));
1050 	}
1051 
1052 	/* connect to server */
1053 	if ((conn = ftp_connect(url, purl, flags)) == NULL)
1054 		return (NULL);
1055 	if (cached_connection)
1056 		ftp_disconnect(cached_connection);
1057 	cached_connection = fetch_ref(conn);
1058 	memcpy(&cached_host, url, sizeof(*url));
1059 	return (conn);
1060 }
1061 
1062 /*
1063  * Check the proxy settings
1064  */
1065 static struct url *
1066 ftp_get_proxy(struct url * url, const char *flags)
1067 {
1068 	struct url *purl;
1069 	char *p;
1070 
1071 	if (flags != NULL && strchr(flags, 'd') != NULL)
1072 		return (NULL);
1073 	if (fetch_no_proxy_match(url->host))
1074 		return (NULL);
1075 	if (((p = getenv("FTP_PROXY")) || (p = getenv("ftp_proxy")) ||
1076 		(p = getenv("HTTP_PROXY")) || (p = getenv("http_proxy"))) &&
1077 	    *p && (purl = fetchParseURL(p)) != NULL) {
1078 		if (!*purl->scheme) {
1079 			if (getenv("FTP_PROXY") || getenv("ftp_proxy"))
1080 				strcpy(purl->scheme, SCHEME_FTP);
1081 			else
1082 				strcpy(purl->scheme, SCHEME_HTTP);
1083 		}
1084 		if (!purl->port)
1085 			purl->port = fetch_default_proxy_port(purl->scheme);
1086 		if (strcmp(purl->scheme, SCHEME_FTP) == 0 ||
1087 		    strcmp(purl->scheme, SCHEME_HTTP) == 0)
1088 			return (purl);
1089 		fetchFreeURL(purl);
1090 	}
1091 	return (NULL);
1092 }
1093 
1094 /*
1095  * Process an FTP request
1096  */
1097 FILE *
1098 ftp_request(struct url *url, const char *op, struct url_stat *us,
1099     struct url *purl, const char *flags)
1100 {
1101 	conn_t *conn;
1102 	int oflag;
1103 
1104 	/* check if we should use HTTP instead */
1105 	if (purl && (strcmp(purl->scheme, SCHEME_HTTP) == 0 ||
1106 	    strcmp(purl->scheme, SCHEME_HTTPS) == 0)) {
1107 		if (strcmp(op, "STAT") == 0)
1108 			return (http_request(url, "HEAD", us, purl, flags));
1109 		else if (strcmp(op, "RETR") == 0)
1110 			return (http_request(url, "GET", us, purl, flags));
1111 		/*
1112 		 * Our HTTP code doesn't support PUT requests yet, so try
1113 		 * a direct connection.
1114 		 */
1115 	}
1116 
1117 	/* connect to server */
1118 	conn = ftp_cached_connect(url, purl, flags);
1119 	if (purl)
1120 		fetchFreeURL(purl);
1121 	if (conn == NULL)
1122 		return (NULL);
1123 
1124 	/* change directory */
1125 	if (ftp_cwd(conn, url->doc) == -1)
1126 		goto errsock;
1127 
1128 	/* stat file */
1129 	if (us && ftp_stat(conn, url->doc, us) == -1
1130 	    && fetchLastErrCode != FETCH_PROTO
1131 	    && fetchLastErrCode != FETCH_UNAVAIL)
1132 		goto errsock;
1133 
1134 	/* just a stat */
1135 	if (strcmp(op, "STAT") == 0) {
1136 		fetch_deref(conn);
1137 		ftp_disconnect(conn);
1138 		return (FILE *)1; /* bogus return value */
1139 	}
1140 	if (strcmp(op, "STOR") == 0 || strcmp(op, "APPE") == 0)
1141 		oflag = O_WRONLY;
1142 	else
1143 		oflag = O_RDONLY;
1144 
1145 	/* initiate the transfer */
1146 	return (ftp_transfer(conn, op, url->doc, oflag, url->offset, flags));
1147 
1148 errsock:
1149 	ftp_disconnect(conn);
1150 	return (NULL);
1151 }
1152 
1153 /*
1154  * Get and stat file
1155  */
1156 FILE *
1157 fetchXGetFTP(struct url *url, struct url_stat *us, const char *flags)
1158 {
1159 	return (ftp_request(url, "RETR", us, ftp_get_proxy(url, flags), flags));
1160 }
1161 
1162 /*
1163  * Get file
1164  */
1165 FILE *
1166 fetchGetFTP(struct url *url, const char *flags)
1167 {
1168 	return (fetchXGetFTP(url, NULL, flags));
1169 }
1170 
1171 /*
1172  * Put file
1173  */
1174 FILE *
1175 fetchPutFTP(struct url *url, const char *flags)
1176 {
1177 	return (ftp_request(url, CHECK_FLAG('a') ? "APPE" : "STOR", NULL,
1178 	    ftp_get_proxy(url, flags), flags));
1179 }
1180 
1181 /*
1182  * Get file stats
1183  */
1184 int
1185 fetchStatFTP(struct url *url, struct url_stat *us, const char *flags)
1186 {
1187 	FILE *f;
1188 
1189 	f = ftp_request(url, "STAT", us, ftp_get_proxy(url, flags), flags);
1190 	if (f == NULL)
1191 		return (-1);
1192 	/*
1193 	 * When op is "STAT", ftp_request() will return either NULL or
1194 	 * (FILE *)1, never a valid FILE *, so we mustn't fclose(f) before
1195 	 * returning, as it would cause a segfault.
1196 	 */
1197 	return (0);
1198 }
1199 
1200 /*
1201  * List a directory
1202  */
1203 struct url_ent *
1204 fetchListFTP(struct url *url __unused, const char *flags __unused)
1205 {
1206 	warnx("fetchListFTP(): not implemented");
1207 	return (NULL);
1208 }
1209