xref: /freebsd/lib/libfetch/ftp.c (revision 7447ca0eb235974642312b9555caec00b57d8fc1)
1 /*-
2  * Copyright (c) 1998-2011 Dag-Erling Smørgrav
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 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 	if (fetch_getln(conn) == -1) {
146 		fetch_syserr();
147 		return (-1);
148 	}
149 	if (isftpinfo(conn->buf)) {
150 		while (conn->buflen && !isftpreply(conn->buf)) {
151 			if (fetch_getln(conn) == -1) {
152 				fetch_syserr();
153 				return (-1);
154 			}
155 		}
156 	}
157 
158 	while (conn->buflen &&
159 	    isspace((unsigned char)conn->buf[conn->buflen - 1]))
160 		conn->buflen--;
161 	conn->buf[conn->buflen] = '\0';
162 
163 	if (!isftpreply(conn->buf)) {
164 		ftp_seterr(FTP_PROTOCOL_ERROR);
165 		return (-1);
166 	}
167 
168 	conn->err = (conn->buf[0] - '0') * 100
169 	    + (conn->buf[1] - '0') * 10
170 	    + (conn->buf[2] - '0');
171 
172 	return (conn->err);
173 }
174 
175 /*
176  * Send a command and check reply
177  */
178 static int
179 ftp_cmd(conn_t *conn, const char *fmt, ...)
180 {
181 	va_list ap;
182 	size_t len;
183 	char *msg;
184 	int r;
185 
186 	va_start(ap, fmt);
187 	len = vasprintf(&msg, fmt, ap);
188 	va_end(ap);
189 
190 	if (msg == NULL) {
191 		errno = ENOMEM;
192 		fetch_syserr();
193 		return (-1);
194 	}
195 
196 	r = fetch_putln(conn, msg, len);
197 	free(msg);
198 
199 	if (r == -1) {
200 		fetch_syserr();
201 		return (-1);
202 	}
203 
204 	return (ftp_chkerr(conn));
205 }
206 
207 /*
208  * Return a pointer to the filename part of a path
209  */
210 static const char *
211 ftp_filename(const char *file, int *len, int *type)
212 {
213 	const char *s;
214 
215 	if ((s = strrchr(file, '/')) == NULL)
216 		s = file;
217 	else
218 		s = s + 1;
219 	*len = strlen(s);
220 	if (*len > 7 && strncmp(s + *len - 7, ";type=", 6) == 0) {
221 		*type = s[*len - 1];
222 		*len -= 7;
223 	} else {
224 		*type = '\0';
225 	}
226 	return (s);
227 }
228 
229 /*
230  * Get current working directory from the reply to a CWD, PWD or CDUP
231  * command.
232  */
233 static int
234 ftp_pwd(conn_t *conn, char *pwd, size_t pwdlen)
235 {
236 	char *src, *dst, *end;
237 	int q;
238 
239 	if (conn->err != FTP_WORKING_DIRECTORY &&
240 	    conn->err != FTP_FILE_ACTION_OK)
241 		return (FTP_PROTOCOL_ERROR);
242 	end = conn->buf + conn->buflen;
243 	src = conn->buf + 4;
244 	if (src >= end || *src++ != '"')
245 		return (FTP_PROTOCOL_ERROR);
246 	for (q = 0, dst = pwd; src < end && pwdlen--; ++src) {
247 		if (!q && *src == '"')
248 			q = 1;
249 		else if (q && *src != '"')
250 			break;
251 		else if (q)
252 			*dst++ = '"', q = 0;
253 		else
254 			*dst++ = *src;
255 	}
256 	if (!pwdlen)
257 		return (FTP_PROTOCOL_ERROR);
258 	*dst = '\0';
259 #if 0
260 	DEBUG(fprintf(stderr, "pwd: [%s]\n", pwd));
261 #endif
262 	return (FTP_OK);
263 }
264 
265 /*
266  * Change working directory to the directory that contains the specified
267  * file.
268  */
269 static int
270 ftp_cwd(conn_t *conn, const char *file)
271 {
272 	const char *beg, *end;
273 	char pwd[PATH_MAX];
274 	int e, i, len;
275 
276 	/* If no slashes in name, no need to change dirs. */
277 	if ((end = strrchr(file, '/')) == NULL)
278 		return (0);
279 	if ((e = ftp_cmd(conn, "PWD")) != FTP_WORKING_DIRECTORY ||
280 	    (e = ftp_pwd(conn, pwd, sizeof(pwd))) != FTP_OK) {
281 		ftp_seterr(e);
282 		return (-1);
283 	}
284 	for (;;) {
285 		len = strlen(pwd);
286 
287 		/* Look for a common prefix between PWD and dir to fetch. */
288 		for (i = 0; i <= len && i <= end - file; ++i)
289 			if (pwd[i] != file[i])
290 				break;
291 #if 0
292 		DEBUG(fprintf(stderr, "have: [%.*s|%s]\n", i, pwd, pwd + i));
293 		DEBUG(fprintf(stderr, "want: [%.*s|%s]\n", i, file, file + i));
294 #endif
295 		/* Keep going up a dir until we have a matching prefix. */
296 		if (pwd[i] == '\0' && (file[i - 1] == '/' || file[i] == '/'))
297 			break;
298 		if ((e = ftp_cmd(conn, "CDUP")) != FTP_FILE_ACTION_OK ||
299 		    (e = ftp_cmd(conn, "PWD")) != FTP_WORKING_DIRECTORY ||
300 		    (e = ftp_pwd(conn, pwd, sizeof(pwd))) != FTP_OK) {
301 			ftp_seterr(e);
302 			return (-1);
303 		}
304 	}
305 
306 #ifdef FTP_COMBINE_CWDS
307 	/* Skip leading slashes, even "////". */
308 	for (beg = file + i; beg < end && *beg == '/'; ++beg, ++i)
309 		/* nothing */ ;
310 
311 	/* If there is no trailing dir, we're already there. */
312 	if (beg >= end)
313 		return (0);
314 
315 	/* Change to the directory all in one chunk (e.g., foo/bar/baz). */
316 	e = ftp_cmd(conn, "CWD %.*s", (int)(end - beg), beg);
317 	if (e == FTP_FILE_ACTION_OK)
318 		return (0);
319 #endif /* FTP_COMBINE_CWDS */
320 
321 	/* That didn't work so go back to legacy behavior (multiple CWDs). */
322 	for (beg = file + i; beg < end; beg = file + i + 1) {
323 		while (*beg == '/')
324 			++beg, ++i;
325 		for (++i; file + i < end && file[i] != '/'; ++i)
326 			/* nothing */ ;
327 		e = ftp_cmd(conn, "CWD %.*s", file + i - beg, beg);
328 		if (e != FTP_FILE_ACTION_OK) {
329 			ftp_seterr(e);
330 			return (-1);
331 		}
332 	}
333 	return (0);
334 }
335 
336 /*
337  * Set transfer mode and data type
338  */
339 static int
340 ftp_mode_type(conn_t *conn, int mode, int type)
341 {
342 	int e;
343 
344 	switch (mode) {
345 	case 0:
346 	case 's':
347 		mode = 'S';
348 	case 'S':
349 		break;
350 	default:
351 		return (FTP_PROTOCOL_ERROR);
352 	}
353 	if ((e = ftp_cmd(conn, "MODE %c", mode)) != FTP_OK) {
354 		if (mode == 'S') {
355 			/*
356 			 * Stream mode is supposed to be the default - so
357 			 * much so that some servers not only do not
358 			 * support any other mode, but do not support the
359 			 * MODE command at all.
360 			 *
361 			 * If "MODE S" fails, it is unlikely that we
362 			 * previously succeeded in setting a different
363 			 * mode.  Therefore, we simply hope that the
364 			 * server is already in the correct mode, and
365 			 * silently ignore the failure.
366 			 */
367 		} else {
368 			return (e);
369 		}
370 	}
371 
372 	switch (type) {
373 	case 0:
374 	case 'i':
375 		type = 'I';
376 	case 'I':
377 		break;
378 	case 'a':
379 		type = 'A';
380 	case 'A':
381 		break;
382 	case 'd':
383 		type = 'D';
384 	case 'D':
385 		/* can't handle yet */
386 	default:
387 		return (FTP_PROTOCOL_ERROR);
388 	}
389 	if ((e = ftp_cmd(conn, "TYPE %c", type)) != FTP_OK)
390 		return (e);
391 
392 	return (FTP_OK);
393 }
394 
395 /*
396  * Request and parse file stats
397  */
398 static int
399 ftp_stat(conn_t *conn, const char *file, struct url_stat *us)
400 {
401 	char *ln;
402 	const char *filename;
403 	int filenamelen, type;
404 	struct tm tm;
405 	time_t t;
406 	int e;
407 
408 	us->size = -1;
409 	us->atime = us->mtime = 0;
410 
411 	filename = ftp_filename(file, &filenamelen, &type);
412 
413 	if ((e = ftp_mode_type(conn, 0, type)) != FTP_OK) {
414 		ftp_seterr(e);
415 		return (-1);
416 	}
417 
418 	e = ftp_cmd(conn, "SIZE %.*s", filenamelen, filename);
419 	if (e != FTP_FILE_STATUS) {
420 		ftp_seterr(e);
421 		return (-1);
422 	}
423 	for (ln = conn->buf + 4; *ln && isspace((unsigned char)*ln); ln++)
424 		/* nothing */ ;
425 	for (us->size = 0; *ln && isdigit((unsigned char)*ln); ln++)
426 		us->size = us->size * 10 + *ln - '0';
427 	if (*ln && !isspace((unsigned char)*ln)) {
428 		ftp_seterr(FTP_PROTOCOL_ERROR);
429 		us->size = -1;
430 		return (-1);
431 	}
432 	if (us->size == 0)
433 		us->size = -1;
434 	DEBUG(fprintf(stderr, "size: [%lld]\n", (long long)us->size));
435 
436 	e = ftp_cmd(conn, "MDTM %.*s", filenamelen, filename);
437 	if (e != FTP_FILE_STATUS) {
438 		ftp_seterr(e);
439 		return (-1);
440 	}
441 	for (ln = conn->buf + 4; *ln && isspace((unsigned char)*ln); ln++)
442 		/* nothing */ ;
443 	switch (strspn(ln, "0123456789")) {
444 	case 14:
445 		break;
446 	case 15:
447 		ln++;
448 		ln[0] = '2';
449 		ln[1] = '0';
450 		break;
451 	default:
452 		ftp_seterr(FTP_PROTOCOL_ERROR);
453 		return (-1);
454 	}
455 	if (sscanf(ln, "%04d%02d%02d%02d%02d%02d",
456 	    &tm.tm_year, &tm.tm_mon, &tm.tm_mday,
457 	    &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
458 		ftp_seterr(FTP_PROTOCOL_ERROR);
459 		return (-1);
460 	}
461 	tm.tm_mon--;
462 	tm.tm_year -= 1900;
463 	tm.tm_isdst = -1;
464 	t = timegm(&tm);
465 	if (t == (time_t)-1)
466 		t = time(NULL);
467 	us->mtime = t;
468 	us->atime = t;
469 	DEBUG(fprintf(stderr,
470 	    "last modified: [%04d-%02d-%02d %02d:%02d:%02d]\n",
471 	    tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
472 	    tm.tm_hour, tm.tm_min, tm.tm_sec));
473 	return (0);
474 }
475 
476 /*
477  * I/O functions for FTP
478  */
479 struct ftpio {
480 	conn_t	*cconn;		/* Control connection */
481 	conn_t	*dconn;		/* Data connection */
482 	int	 dir;		/* Direction */
483 	int	 eof;		/* EOF reached */
484 	int	 err;		/* Error code */
485 };
486 
487 static int	 ftp_readfn(void *, char *, int);
488 static int	 ftp_writefn(void *, const char *, int);
489 static fpos_t	 ftp_seekfn(void *, fpos_t, int);
490 static int	 ftp_closefn(void *);
491 
492 static int
493 ftp_readfn(void *v, char *buf, int len)
494 {
495 	struct ftpio *io;
496 	int r;
497 
498 	io = (struct ftpio *)v;
499 	if (io == NULL) {
500 		errno = EBADF;
501 		return (-1);
502 	}
503 	if (io->cconn == NULL || io->dconn == NULL || io->dir == O_WRONLY) {
504 		errno = EBADF;
505 		return (-1);
506 	}
507 	if (io->err) {
508 		errno = io->err;
509 		return (-1);
510 	}
511 	if (io->eof)
512 		return (0);
513 	r = fetch_read(io->dconn, buf, len);
514 	if (r > 0)
515 		return (r);
516 	if (r == 0) {
517 		io->eof = 1;
518 		return (0);
519 	}
520 	if (errno != EINTR)
521 		io->err = errno;
522 	return (-1);
523 }
524 
525 static int
526 ftp_writefn(void *v, const char *buf, int len)
527 {
528 	struct ftpio *io;
529 	int w;
530 
531 	io = (struct ftpio *)v;
532 	if (io == NULL) {
533 		errno = EBADF;
534 		return (-1);
535 	}
536 	if (io->cconn == NULL || io->dconn == NULL || io->dir == O_RDONLY) {
537 		errno = EBADF;
538 		return (-1);
539 	}
540 	if (io->err) {
541 		errno = io->err;
542 		return (-1);
543 	}
544 	w = fetch_write(io->dconn, buf, len);
545 	if (w >= 0)
546 		return (w);
547 	if (errno != EINTR)
548 		io->err = errno;
549 	return (-1);
550 }
551 
552 static fpos_t
553 ftp_seekfn(void *v, fpos_t pos __unused, int whence __unused)
554 {
555 	struct ftpio *io;
556 
557 	io = (struct ftpio *)v;
558 	if (io == NULL) {
559 		errno = EBADF;
560 		return (-1);
561 	}
562 	errno = ESPIPE;
563 	return (-1);
564 }
565 
566 static int
567 ftp_closefn(void *v)
568 {
569 	struct ftpio *io;
570 	int r;
571 
572 	io = (struct ftpio *)v;
573 	if (io == NULL) {
574 		errno = EBADF;
575 		return (-1);
576 	}
577 	if (io->dir == -1)
578 		return (0);
579 	if (io->cconn == NULL || io->dconn == NULL) {
580 		errno = EBADF;
581 		return (-1);
582 	}
583 	fetch_close(io->dconn);
584 	io->dir = -1;
585 	io->dconn = NULL;
586 	DEBUG(fprintf(stderr, "Waiting for final status\n"));
587 	r = ftp_chkerr(io->cconn);
588 	if (io->cconn == cached_connection && io->cconn->ref == 1)
589 		cached_connection = NULL;
590 	fetch_close(io->cconn);
591 	free(io);
592 	return (r == FTP_TRANSFER_COMPLETE) ? 0 : -1;
593 }
594 
595 static FILE *
596 ftp_setup(conn_t *cconn, conn_t *dconn, int mode)
597 {
598 	struct ftpio *io;
599 	FILE *f;
600 
601 	if (cconn == NULL || dconn == NULL)
602 		return (NULL);
603 	if ((io = malloc(sizeof(*io))) == NULL)
604 		return (NULL);
605 	io->cconn = cconn;
606 	io->dconn = dconn;
607 	io->dir = mode;
608 	io->eof = io->err = 0;
609 	f = funopen(io, ftp_readfn, ftp_writefn, ftp_seekfn, ftp_closefn);
610 	if (f == NULL)
611 		free(io);
612 	return (f);
613 }
614 
615 /*
616  * Transfer file
617  */
618 static FILE *
619 ftp_transfer(conn_t *conn, const char *oper, const char *file,
620     int mode, off_t offset, const char *flags)
621 {
622 	struct sockaddr_storage sa;
623 	struct sockaddr_in6 *sin6;
624 	struct sockaddr_in *sin4;
625 	const char *bindaddr;
626 	const char *filename;
627 	int filenamelen, type;
628 	int low, pasv, verbose;
629 	int e, sd = -1;
630 	socklen_t l;
631 	char *s;
632 	FILE *df;
633 
634 	/* check flags */
635 	low = CHECK_FLAG('l');
636 	pasv = CHECK_FLAG('p') || !CHECK_FLAG('P');
637 	verbose = CHECK_FLAG('v');
638 
639 	/* passive mode */
640 	if ((s = getenv("FTP_PASSIVE_MODE")) != NULL)
641 		pasv = (strncasecmp(s, "no", 2) != 0);
642 
643 	/* isolate filename */
644 	filename = ftp_filename(file, &filenamelen, &type);
645 
646 	/* set transfer mode and data type */
647 	if ((e = ftp_mode_type(conn, 0, type)) != FTP_OK)
648 		goto ouch;
649 
650 	/* find our own address, bind, and listen */
651 	l = sizeof(sa);
652 	if (getsockname(conn->sd, (struct sockaddr *)&sa, &l) == -1)
653 		goto sysouch;
654 	if (sa.ss_family == AF_INET6)
655 		unmappedaddr((struct sockaddr_in6 *)&sa);
656 
657 	/* open data socket */
658 	if ((sd = socket(sa.ss_family, SOCK_STREAM, IPPROTO_TCP)) == -1) {
659 		fetch_syserr();
660 		return (NULL);
661 	}
662 
663 	if (pasv) {
664 		u_char addr[64];
665 		char *ln, *p;
666 		unsigned int i;
667 		int port;
668 
669 		/* send PASV command */
670 		if (verbose)
671 			fetch_info("setting passive mode");
672 		switch (sa.ss_family) {
673 		case AF_INET:
674 			if ((e = ftp_cmd(conn, "PASV")) != FTP_PASSIVE_MODE)
675 				goto ouch;
676 			break;
677 		case AF_INET6:
678 			if ((e = ftp_cmd(conn, "EPSV")) != FTP_EPASSIVE_MODE) {
679 				if (e == -1)
680 					goto ouch;
681 				if ((e = ftp_cmd(conn, "LPSV")) !=
682 				    FTP_LPASSIVE_MODE)
683 					goto ouch;
684 			}
685 			break;
686 		default:
687 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
688 			goto ouch;
689 		}
690 
691 		/*
692 		 * Find address and port number. The reply to the PASV command
693 		 * is IMHO the one and only weak point in the FTP protocol.
694 		 */
695 		ln = conn->buf;
696 		switch (e) {
697 		case FTP_PASSIVE_MODE:
698 		case FTP_LPASSIVE_MODE:
699 			for (p = ln + 3; *p && !isdigit((unsigned char)*p); p++)
700 				/* nothing */ ;
701 			if (!*p) {
702 				e = FTP_PROTOCOL_ERROR;
703 				goto ouch;
704 			}
705 			l = (e == FTP_PASSIVE_MODE ? 6 : 21);
706 			for (i = 0; *p && i < l; i++, p++)
707 				addr[i] = strtol(p, &p, 10);
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 		    fetch_bind(sd, sa.ss_family, bindaddr) != 0)
772 			goto sysouch;
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 		user = getenv("FTP_LOGIN");
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 			pwd = getenv("FTP_PASSWORD");
931 		if (pwd == NULL || *pwd == '\0') {
932 			if ((logname = getlogin()) == NULL)
933 				logname = FTP_ANONYMOUS_USER;
934 			if ((len = snprintf(pbuf, MAXLOGNAME + 1, "%s@", logname)) < 0)
935 				len = 0;
936 			else if (len > MAXLOGNAME)
937 				len = MAXLOGNAME;
938 			gethostname(pbuf + len, sizeof(pbuf) - len);
939 			pwd = pbuf;
940 		}
941 		e = ftp_cmd(conn, "PASS %s", pwd);
942 	}
943 
944 	return (e);
945 }
946 
947 /*
948  * Log on to FTP server
949  */
950 static conn_t *
951 ftp_connect(struct url *url, struct url *purl, const char *flags)
952 {
953 	conn_t *conn;
954 	int e, direct, verbose;
955 #ifdef INET6
956 	int af = AF_UNSPEC;
957 #else
958 	int af = AF_INET;
959 #endif
960 
961 	direct = CHECK_FLAG('d');
962 	verbose = CHECK_FLAG('v');
963 	if (CHECK_FLAG('4'))
964 		af = AF_INET;
965 	else if (CHECK_FLAG('6'))
966 		af = AF_INET6;
967 
968 	if (direct)
969 		purl = NULL;
970 
971 	/* check for proxy */
972 	if (purl) {
973 		/* XXX proxy authentication! */
974 		conn = fetch_connect(purl->host, purl->port, af, verbose);
975 	} else {
976 		/* no proxy, go straight to target */
977 		conn = fetch_connect(url->host, url->port, af, verbose);
978 		purl = NULL;
979 	}
980 
981 	/* check connection */
982 	if (conn == NULL)
983 		/* fetch_connect() has already set an error code */
984 		return (NULL);
985 
986 	/* expect welcome message */
987 	if ((e = ftp_chkerr(conn)) != FTP_SERVICE_READY)
988 		goto fouch;
989 
990 	/* authenticate */
991 	if ((e = ftp_authenticate(conn, url, purl)) != FTP_LOGGED_IN)
992 		goto fouch;
993 
994 	/* TODO: Request extended features supported, if any (RFC 3659). */
995 
996 	/* done */
997 	return (conn);
998 
999 fouch:
1000 	if (e != -1)
1001 		ftp_seterr(e);
1002 	fetch_close(conn);
1003 	return (NULL);
1004 }
1005 
1006 /*
1007  * Disconnect from server
1008  */
1009 static void
1010 ftp_disconnect(conn_t *conn)
1011 {
1012 	(void)ftp_cmd(conn, "QUIT");
1013 	if (conn == cached_connection && conn->ref == 1)
1014 		cached_connection = NULL;
1015 	fetch_close(conn);
1016 }
1017 
1018 /*
1019  * Check if we're already connected
1020  */
1021 static int
1022 ftp_isconnected(struct url *url)
1023 {
1024 	return (cached_connection
1025 	    && (strcmp(url->host, cached_host.host) == 0)
1026 	    && (strcmp(url->user, cached_host.user) == 0)
1027 	    && (strcmp(url->pwd, cached_host.pwd) == 0)
1028 	    && (url->port == cached_host.port));
1029 }
1030 
1031 /*
1032  * Check the cache, reconnect if no luck
1033  */
1034 static conn_t *
1035 ftp_cached_connect(struct url *url, struct url *purl, const char *flags)
1036 {
1037 	conn_t *conn;
1038 	int e;
1039 
1040 	/* set default port */
1041 	if (!url->port)
1042 		url->port = fetch_default_port(url->scheme);
1043 
1044 	/* try to use previously cached connection */
1045 	if (ftp_isconnected(url)) {
1046 		e = ftp_cmd(cached_connection, "NOOP");
1047 		if (e == FTP_OK || e == FTP_SYNTAX_ERROR)
1048 			return (fetch_ref(cached_connection));
1049 	}
1050 
1051 	/* connect to server */
1052 	if ((conn = ftp_connect(url, purl, flags)) == NULL)
1053 		return (NULL);
1054 	if (cached_connection)
1055 		ftp_disconnect(cached_connection);
1056 	cached_connection = fetch_ref(conn);
1057 	memcpy(&cached_host, url, sizeof(*url));
1058 	return (conn);
1059 }
1060 
1061 /*
1062  * Check the proxy settings
1063  */
1064 static struct url *
1065 ftp_get_proxy(struct url * url, const char *flags)
1066 {
1067 	struct url *purl;
1068 	char *p;
1069 
1070 	if (flags != NULL && strchr(flags, 'd') != NULL)
1071 		return (NULL);
1072 	if (fetch_no_proxy_match(url->host))
1073 		return (NULL);
1074 	if (((p = getenv("FTP_PROXY")) || (p = getenv("ftp_proxy")) ||
1075 		(p = getenv("HTTP_PROXY")) || (p = getenv("http_proxy"))) &&
1076 	    *p && (purl = fetchParseURL(p)) != NULL) {
1077 		if (!*purl->scheme) {
1078 			if (getenv("FTP_PROXY") || getenv("ftp_proxy"))
1079 				strcpy(purl->scheme, SCHEME_FTP);
1080 			else
1081 				strcpy(purl->scheme, SCHEME_HTTP);
1082 		}
1083 		if (!purl->port)
1084 			purl->port = fetch_default_proxy_port(purl->scheme);
1085 		if (strcasecmp(purl->scheme, SCHEME_FTP) == 0 ||
1086 		    strcasecmp(purl->scheme, SCHEME_HTTP) == 0)
1087 			return (purl);
1088 		fetchFreeURL(purl);
1089 	}
1090 	return (NULL);
1091 }
1092 
1093 /*
1094  * Process an FTP request
1095  */
1096 FILE *
1097 ftp_request(struct url *url, const char *op, struct url_stat *us,
1098     struct url *purl, const char *flags)
1099 {
1100 	conn_t *conn;
1101 	int oflag;
1102 
1103 	/* check if we should use HTTP instead */
1104 	if (purl && strcasecmp(purl->scheme, SCHEME_HTTP) == 0) {
1105 		if (strcmp(op, "STAT") == 0)
1106 			return (http_request(url, "HEAD", us, purl, flags));
1107 		else if (strcmp(op, "RETR") == 0)
1108 			return (http_request(url, "GET", us, purl, flags));
1109 		/*
1110 		 * Our HTTP code doesn't support PUT requests yet, so try
1111 		 * a direct connection.
1112 		 */
1113 	}
1114 
1115 	/* connect to server */
1116 	conn = ftp_cached_connect(url, purl, flags);
1117 	if (purl)
1118 		fetchFreeURL(purl);
1119 	if (conn == NULL)
1120 		return (NULL);
1121 
1122 	/* change directory */
1123 	if (ftp_cwd(conn, url->doc) == -1)
1124 		goto errsock;
1125 
1126 	/* stat file */
1127 	if (us && ftp_stat(conn, url->doc, us) == -1
1128 	    && fetchLastErrCode != FETCH_PROTO
1129 	    && fetchLastErrCode != FETCH_UNAVAIL)
1130 		goto errsock;
1131 
1132 	/* just a stat */
1133 	if (strcmp(op, "STAT") == 0) {
1134 		--conn->ref;
1135 		ftp_disconnect(conn);
1136 		return (FILE *)1; /* bogus return value */
1137 	}
1138 	if (strcmp(op, "STOR") == 0 || strcmp(op, "APPE") == 0)
1139 		oflag = O_WRONLY;
1140 	else
1141 		oflag = O_RDONLY;
1142 
1143 	/* initiate the transfer */
1144 	return (ftp_transfer(conn, op, url->doc, oflag, url->offset, flags));
1145 
1146 errsock:
1147 	ftp_disconnect(conn);
1148 	return (NULL);
1149 }
1150 
1151 /*
1152  * Get and stat file
1153  */
1154 FILE *
1155 fetchXGetFTP(struct url *url, struct url_stat *us, const char *flags)
1156 {
1157 	return (ftp_request(url, "RETR", us, ftp_get_proxy(url, flags), flags));
1158 }
1159 
1160 /*
1161  * Get file
1162  */
1163 FILE *
1164 fetchGetFTP(struct url *url, const char *flags)
1165 {
1166 	return (fetchXGetFTP(url, NULL, flags));
1167 }
1168 
1169 /*
1170  * Put file
1171  */
1172 FILE *
1173 fetchPutFTP(struct url *url, const char *flags)
1174 {
1175 	return (ftp_request(url, CHECK_FLAG('a') ? "APPE" : "STOR", NULL,
1176 	    ftp_get_proxy(url, flags), flags));
1177 }
1178 
1179 /*
1180  * Get file stats
1181  */
1182 int
1183 fetchStatFTP(struct url *url, struct url_stat *us, const char *flags)
1184 {
1185 	FILE *f;
1186 
1187 	f = ftp_request(url, "STAT", us, ftp_get_proxy(url, flags), flags);
1188 	if (f == NULL)
1189 		return (-1);
1190 	/*
1191 	 * When op is "STAT", ftp_request() will return either NULL or
1192 	 * (FILE *)1, never a valid FILE *, so we mustn't fclose(f) before
1193 	 * returning, as it would cause a segfault.
1194 	 */
1195 	return (0);
1196 }
1197 
1198 /*
1199  * List a directory
1200  */
1201 struct url_ent *
1202 fetchListFTP(struct url *url __unused, const char *flags __unused)
1203 {
1204 	warnx("fetchListFTP(): not implemented");
1205 	return (NULL);
1206 }
1207