xref: /freebsd/lib/libfetch/ftp.c (revision 2be1a816b9ff69588e55be0a84cbe2a31efc0f2f)
1 /*-
2  * Copyright (c) 1998-2004 Dag-Erling Co�dan Sm�rgrav
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer
10  *    in this position and unchanged.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. The name of the author may not be used to endorse or promote products
15  *    derived from this software without specific prior written permission
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 /*
33  * Portions of this code were taken from or based on ftpio.c:
34  *
35  * ----------------------------------------------------------------------------
36  * "THE BEER-WARE LICENSE" (Revision 42):
37  * <phk@FreeBSD.org> wrote this file.  As long as you retain this notice you
38  * can do whatever you want with this stuff. If we meet some day, and you think
39  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
40  * ----------------------------------------------------------------------------
41  *
42  * Major Changelog:
43  *
44  * Dag-Erling Co�dan Sm�rgrav
45  * 9 Jun 1998
46  *
47  * Incorporated into libfetch
48  *
49  * Jordan K. Hubbard
50  * 17 Jan 1996
51  *
52  * Turned inside out. Now returns xfers as new file ids, not as a special
53  * `state' of FTP_t
54  *
55  * $ftpioId: ftpio.c,v 1.30 1998/04/11 07:28:53 phk Exp $
56  *
57  */
58 
59 #include <sys/param.h>
60 #include <sys/socket.h>
61 #include <netinet/in.h>
62 
63 #include <ctype.h>
64 #include <err.h>
65 #include <errno.h>
66 #include <fcntl.h>
67 #include <netdb.h>
68 #include <stdarg.h>
69 #include <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 *)&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');
637 	verbose = CHECK_FLAG('v');
638 
639 	/* passive mode */
640 	if (!pasv)
641 		pasv = ((s = getenv("FTP_PASSIVE_MODE")) != NULL &&
642 		    strncasecmp(s, "no", 2) != 0);
643 
644 	/* isolate filename */
645 	filename = ftp_filename(file, &filenamelen, &type);
646 
647 	/* set transfer mode and data type */
648 	if ((e = ftp_mode_type(conn, 0, type)) != FTP_OK)
649 		goto ouch;
650 
651 	/* find our own address, bind, and listen */
652 	l = sizeof(sa);
653 	if (getsockname(conn->sd, (struct sockaddr *)&sa, &l) == -1)
654 		goto sysouch;
655 	if (sa.ss_family == AF_INET6)
656 		unmappedaddr((struct sockaddr_in6 *)&sa);
657 
658 	/* open data socket */
659 	if ((sd = socket(sa.ss_family, SOCK_STREAM, IPPROTO_TCP)) == -1) {
660 		fetch_syserr();
661 		return (NULL);
662 	}
663 
664 	if (pasv) {
665 		u_char addr[64];
666 		char *ln, *p;
667 		unsigned int i;
668 		int port;
669 
670 		/* send PASV command */
671 		if (verbose)
672 			fetch_info("setting passive mode");
673 		switch (sa.ss_family) {
674 		case AF_INET:
675 			if ((e = ftp_cmd(conn, "PASV")) != FTP_PASSIVE_MODE)
676 				goto ouch;
677 			break;
678 		case AF_INET6:
679 			if ((e = ftp_cmd(conn, "EPSV")) != FTP_EPASSIVE_MODE) {
680 				if (e == -1)
681 					goto ouch;
682 				if ((e = ftp_cmd(conn, "LPSV")) !=
683 				    FTP_LPASSIVE_MODE)
684 					goto ouch;
685 			}
686 			break;
687 		default:
688 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
689 			goto ouch;
690 		}
691 
692 		/*
693 		 * Find address and port number. The reply to the PASV command
694 		 * is IMHO the one and only weak point in the FTP protocol.
695 		 */
696 		ln = conn->buf;
697 		switch (e) {
698 		case FTP_PASSIVE_MODE:
699 		case FTP_LPASSIVE_MODE:
700 			for (p = ln + 3; *p && !isdigit((unsigned char)*p); p++)
701 				/* nothing */ ;
702 			if (!*p) {
703 				e = FTP_PROTOCOL_ERROR;
704 				goto ouch;
705 			}
706 			l = (e == FTP_PASSIVE_MODE ? 6 : 21);
707 			for (i = 0; *p && i < l; i++, p++)
708 				addr[i] = strtol(p, &p, 10);
709 			if (i < l) {
710 				e = FTP_PROTOCOL_ERROR;
711 				goto ouch;
712 			}
713 			break;
714 		case FTP_EPASSIVE_MODE:
715 			for (p = ln + 3; *p && *p != '('; p++)
716 				/* nothing */ ;
717 			if (!*p) {
718 				e = FTP_PROTOCOL_ERROR;
719 				goto ouch;
720 			}
721 			++p;
722 			if (sscanf(p, "%c%c%c%d%c", &addr[0], &addr[1], &addr[2],
723 				&port, &addr[3]) != 5 ||
724 			    addr[0] != addr[1] ||
725 			    addr[0] != addr[2] || addr[0] != addr[3]) {
726 				e = FTP_PROTOCOL_ERROR;
727 				goto ouch;
728 			}
729 			break;
730 		}
731 
732 		/* seek to required offset */
733 		if (offset)
734 			if (ftp_cmd(conn, "REST %lu", (u_long)offset) != FTP_FILE_OK)
735 				goto sysouch;
736 
737 		/* construct sockaddr for data socket */
738 		l = sizeof(sa);
739 		if (getpeername(conn->sd, (struct sockaddr *)&sa, &l) == -1)
740 			goto sysouch;
741 		if (sa.ss_family == AF_INET6)
742 			unmappedaddr((struct sockaddr_in6 *)&sa);
743 		switch (sa.ss_family) {
744 		case AF_INET6:
745 			sin6 = (struct sockaddr_in6 *)&sa;
746 			if (e == FTP_EPASSIVE_MODE)
747 				sin6->sin6_port = htons(port);
748 			else {
749 				memcpy(&sin6->sin6_addr, addr + 2, 16);
750 				memcpy(&sin6->sin6_port, addr + 19, 2);
751 			}
752 			break;
753 		case AF_INET:
754 			sin4 = (struct sockaddr_in *)&sa;
755 			if (e == FTP_EPASSIVE_MODE)
756 				sin4->sin_port = htons(port);
757 			else {
758 				memcpy(&sin4->sin_addr, addr, 4);
759 				memcpy(&sin4->sin_port, addr + 4, 2);
760 			}
761 			break;
762 		default:
763 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
764 			break;
765 		}
766 
767 		/* connect to data port */
768 		if (verbose)
769 			fetch_info("opening data connection");
770 		bindaddr = getenv("FETCH_BIND_ADDRESS");
771 		if (bindaddr != NULL && *bindaddr != '\0' &&
772 		    fetch_bind(sd, sa.ss_family, bindaddr) != 0)
773 			goto sysouch;
774 		if (connect(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
775 			goto sysouch;
776 
777 		/* make the server initiate the transfer */
778 		if (verbose)
779 			fetch_info("initiating transfer");
780 		e = ftp_cmd(conn, "%s %.*s", oper, filenamelen, filename);
781 		if (e != FTP_CONNECTION_ALREADY_OPEN && e != FTP_OPEN_DATA_CONNECTION)
782 			goto ouch;
783 
784 	} else {
785 		u_int32_t a;
786 		u_short p;
787 		int arg, d;
788 		char *ap;
789 		char hname[INET6_ADDRSTRLEN];
790 
791 		switch (sa.ss_family) {
792 		case AF_INET6:
793 			((struct sockaddr_in6 *)&sa)->sin6_port = 0;
794 #ifdef IPV6_PORTRANGE
795 			arg = low ? IPV6_PORTRANGE_DEFAULT : IPV6_PORTRANGE_HIGH;
796 			if (setsockopt(sd, IPPROTO_IPV6, IPV6_PORTRANGE,
797 				(char *)&arg, sizeof(arg)) == -1)
798 				goto sysouch;
799 #endif
800 			break;
801 		case AF_INET:
802 			((struct sockaddr_in *)&sa)->sin_port = 0;
803 			arg = low ? IP_PORTRANGE_DEFAULT : IP_PORTRANGE_HIGH;
804 			if (setsockopt(sd, IPPROTO_IP, IP_PORTRANGE,
805 				(char *)&arg, sizeof(arg)) == -1)
806 				goto sysouch;
807 			break;
808 		}
809 		if (verbose)
810 			fetch_info("binding data socket");
811 		if (bind(sd, (struct sockaddr *)&sa, sa.ss_len) == -1)
812 			goto sysouch;
813 		if (listen(sd, 1) == -1)
814 			goto sysouch;
815 
816 		/* find what port we're on and tell the server */
817 		if (getsockname(sd, (struct sockaddr *)&sa, &l) == -1)
818 			goto sysouch;
819 		switch (sa.ss_family) {
820 		case AF_INET:
821 			sin4 = (struct sockaddr_in *)&sa;
822 			a = ntohl(sin4->sin_addr.s_addr);
823 			p = ntohs(sin4->sin_port);
824 			e = ftp_cmd(conn, "PORT %d,%d,%d,%d,%d,%d",
825 			    (a >> 24) & 0xff, (a >> 16) & 0xff,
826 			    (a >> 8) & 0xff, a & 0xff,
827 			    (p >> 8) & 0xff, p & 0xff);
828 			break;
829 		case AF_INET6:
830 #define UC(b)	(((int)b)&0xff)
831 			e = -1;
832 			sin6 = (struct sockaddr_in6 *)&sa;
833 			sin6->sin6_scope_id = 0;
834 			if (getnameinfo((struct sockaddr *)&sa, sa.ss_len,
835 				hname, sizeof(hname),
836 				NULL, 0, NI_NUMERICHOST) == 0) {
837 				e = ftp_cmd(conn, "EPRT |%d|%s|%d|", 2, hname,
838 				    htons(sin6->sin6_port));
839 				if (e == -1)
840 					goto ouch;
841 			}
842 			if (e != FTP_OK) {
843 				ap = (char *)&sin6->sin6_addr;
844 				e = ftp_cmd(conn,
845 				    "LPRT %d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",
846 				    6, 16,
847 				    UC(ap[0]), UC(ap[1]), UC(ap[2]), UC(ap[3]),
848 				    UC(ap[4]), UC(ap[5]), UC(ap[6]), UC(ap[7]),
849 				    UC(ap[8]), UC(ap[9]), UC(ap[10]), UC(ap[11]),
850 				    UC(ap[12]), UC(ap[13]), UC(ap[14]), UC(ap[15]),
851 				    2,
852 				    (ntohs(sin6->sin6_port) >> 8) & 0xff,
853 				    ntohs(sin6->sin6_port)        & 0xff);
854 			}
855 			break;
856 		default:
857 			e = FTP_PROTOCOL_ERROR; /* XXX: error code should be prepared */
858 			goto ouch;
859 		}
860 		if (e != FTP_OK)
861 			goto ouch;
862 
863 		/* seek to required offset */
864 		if (offset)
865 			if (ftp_cmd(conn, "REST %ju", (uintmax_t)offset) != FTP_FILE_OK)
866 				goto sysouch;
867 
868 		/* make the server initiate the transfer */
869 		if (verbose)
870 			fetch_info("initiating transfer");
871 		e = ftp_cmd(conn, "%s %.*s", oper, filenamelen, filename);
872 		if (e != FTP_CONNECTION_ALREADY_OPEN && e != FTP_OPEN_DATA_CONNECTION)
873 			goto ouch;
874 
875 		/* accept the incoming connection and go to town */
876 		if ((d = accept(sd, NULL, NULL)) == -1)
877 			goto sysouch;
878 		close(sd);
879 		sd = d;
880 	}
881 
882 	if ((df = ftp_setup(conn, fetch_reopen(sd), mode)) == NULL)
883 		goto sysouch;
884 	return (df);
885 
886 sysouch:
887 	fetch_syserr();
888 	if (sd >= 0)
889 		close(sd);
890 	return (NULL);
891 
892 ouch:
893 	if (e != -1)
894 		ftp_seterr(e);
895 	if (sd >= 0)
896 		close(sd);
897 	return (NULL);
898 }
899 
900 /*
901  * Authenticate
902  */
903 static int
904 ftp_authenticate(conn_t *conn, struct url *url, struct url *purl)
905 {
906 	const char *user, *pwd, *logname;
907 	char pbuf[MAXHOSTNAMELEN + MAXLOGNAME + 1];
908 	int e, len;
909 
910 	/* XXX FTP_AUTH, and maybe .netrc */
911 
912 	/* send user name and password */
913 	if (url->user[0] == '\0')
914 		fetch_netrc_auth(url);
915 	user = url->user;
916 	if (*user == '\0')
917 		user = getenv("FTP_LOGIN");
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 			pwd = getenv("FTP_PASSWORD");
932 		if (pwd == NULL || *pwd == '\0') {
933 			if ((logname = getlogin()) == 0)
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 (strcasecmp(purl->scheme, SCHEME_FTP) == 0 ||
1087 		    strcasecmp(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 && strcasecmp(purl->scheme, SCHEME_HTTP) == 0) {
1106 		if (strcmp(op, "STAT") == 0)
1107 			return (http_request(url, "HEAD", us, purl, flags));
1108 		else if (strcmp(op, "RETR") == 0)
1109 			return (http_request(url, "GET", us, purl, flags));
1110 		/*
1111 		 * Our HTTP code doesn't support PUT requests yet, so try
1112 		 * a direct connection.
1113 		 */
1114 	}
1115 
1116 	/* connect to server */
1117 	conn = ftp_cached_connect(url, purl, flags);
1118 	if (purl)
1119 		fetchFreeURL(purl);
1120 	if (conn == NULL)
1121 		return (NULL);
1122 
1123 	/* change directory */
1124 	if (ftp_cwd(conn, url->doc) == -1)
1125 		return (NULL);
1126 
1127 	/* stat file */
1128 	if (us && ftp_stat(conn, url->doc, us) == -1
1129 	    && fetchLastErrCode != FETCH_PROTO
1130 	    && fetchLastErrCode != FETCH_UNAVAIL)
1131 		return (NULL);
1132 
1133 	/* just a stat */
1134 	if (strcmp(op, "STAT") == 0)
1135 		return (FILE *)1; /* bogus return value */
1136 	if (strcmp(op, "STOR") == 0 || strcmp(op, "APPE") == 0)
1137 		oflag = O_WRONLY;
1138 	else
1139 		oflag = O_RDONLY;
1140 
1141 	/* initiate the transfer */
1142 	return (ftp_transfer(conn, op, url->doc, oflag, url->offset, flags));
1143 }
1144 
1145 /*
1146  * Get and stat file
1147  */
1148 FILE *
1149 fetchXGetFTP(struct url *url, struct url_stat *us, const char *flags)
1150 {
1151 	return (ftp_request(url, "RETR", us, ftp_get_proxy(url, flags), flags));
1152 }
1153 
1154 /*
1155  * Get file
1156  */
1157 FILE *
1158 fetchGetFTP(struct url *url, const char *flags)
1159 {
1160 	return (fetchXGetFTP(url, NULL, flags));
1161 }
1162 
1163 /*
1164  * Put file
1165  */
1166 FILE *
1167 fetchPutFTP(struct url *url, const char *flags)
1168 {
1169 	return (ftp_request(url, CHECK_FLAG('a') ? "APPE" : "STOR", NULL,
1170 	    ftp_get_proxy(url, flags), flags));
1171 }
1172 
1173 /*
1174  * Get file stats
1175  */
1176 int
1177 fetchStatFTP(struct url *url, struct url_stat *us, const char *flags)
1178 {
1179 	FILE *f;
1180 
1181 	f = ftp_request(url, "STAT", us, ftp_get_proxy(url, flags), flags);
1182 	if (f == NULL)
1183 		return (-1);
1184 	/*
1185 	 * When op is "STAT", ftp_request() will return either NULL or
1186 	 * (FILE *)1, never a valid FILE *, so we mustn't fclose(f) before
1187 	 * returning, as it would cause a segfault.
1188 	 */
1189 	return (0);
1190 }
1191 
1192 /*
1193  * List a directory
1194  */
1195 struct url_ent *
1196 fetchListFTP(struct url *url __unused, const char *flags __unused)
1197 {
1198 	warnx("fetchListFTP(): not implemented");
1199 	return (NULL);
1200 }
1201