aboutsummaryrefslogtreecommitdiff
path: root/networking/wget.c
blob: fb8e51317762c9b55dbfe86ff8ea845a8e2650af (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
/* vi: set sw=4 ts=4: */
/*
 * wget - retrieve a file using HTTP or FTP
 *
 * Chip Rosenthal Covad Communications <chip@laserlink.net>
 * Licensed under GPLv2, see file LICENSE in this tarball for details.
 *
 * Copyright (C) 2010 Bradley M. Kuhn <bkuhn@ebb.org>
 *   Kuhn's copyrights are licensed GPLv2-or-later.  File as a whole remains GPLv2.
 */
#include "libbb.h"

struct host_info {
	// May be used if we ever will want to free() all xstrdup()s...
	/* char *allocated; */
	const char *path;
	const char *user;
	char       *host;
	int         port;
	smallint    is_ftp;
};


/* Globals */
struct globals {
	off_t content_len;        /* Content-length of the file */
	off_t beg_range;          /* Range at which continue begins */
#if ENABLE_FEATURE_WGET_STATUSBAR
	off_t transferred;        /* Number of bytes transferred so far */
	const char *curfile;      /* Name of current file being transferred */
	bb_progress_t pmt;
#endif
#if ENABLE_FEATURE_WGET_TIMEOUT
	unsigned timeout_seconds;
#endif
	smallint chunked;         /* chunked transfer encoding */
	smallint got_clen;        /* got content-length: from server  */
} FIX_ALIASING;
#define G (*(struct globals*)&bb_common_bufsiz1)
struct BUG_G_too_big {
	char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
};
#define INIT_G() do { \
	IF_FEATURE_WGET_TIMEOUT(G.timeout_seconds = 900;) \
} while (0)


/* Must match option string! */
enum {
	WGET_OPT_CONTINUE   = (1 << 0),
	WGET_OPT_SPIDER	    = (1 << 1),
	WGET_OPT_QUIET      = (1 << 2),
	WGET_OPT_OUTNAME    = (1 << 3),
	WGET_OPT_PREFIX     = (1 << 4),
	WGET_OPT_PROXY      = (1 << 5),
	WGET_OPT_USER_AGENT = (1 << 6),
	WGET_OPT_NETWORK_READ_TIMEOUT = (1 << 7),
	WGET_OPT_RETRIES    = (1 << 8),
	WGET_OPT_PASSIVE    = (1 << 9),
	WGET_OPT_HEADER     = (1 << 10) * ENABLE_FEATURE_WGET_LONG_OPTIONS,
	WGET_OPT_POST_DATA  = (1 << 11) * ENABLE_FEATURE_WGET_LONG_OPTIONS,
};

enum {
	PROGRESS_START = -1,
	PROGRESS_END   = 0,
	PROGRESS_BUMP  = 1,
};
#if ENABLE_FEATURE_WGET_STATUSBAR
static void progress_meter(int flag)
{
	if (option_mask32 & WGET_OPT_QUIET)
		return;

	if (flag == PROGRESS_START)
		bb_progress_init(&G.pmt);

	bb_progress_update(&G.pmt, G.curfile, G.beg_range, G.transferred,
			   G.chunked ? 0 : G.beg_range + G.transferred + G.content_len);

	if (flag == PROGRESS_END) {
		bb_putchar_stderr('\n');
		G.transferred = 0;
	}
}
#else
static ALWAYS_INLINE void progress_meter(int flag UNUSED_PARAM) { }
#endif


/* IPv6 knows scoped address types i.e. link and site local addresses. Link
 * local addresses can have a scope identifier to specify the
 * interface/link an address is valid on (e.g. fe80::1%eth0). This scope
 * identifier is only valid on a single node.
 *
 * RFC 4007 says that the scope identifier MUST NOT be sent across the wire,
 * unless all nodes agree on the semantic. Apache e.g. regards zone identifiers
 * in the Host header as invalid requests, see
 * https://issues.apache.org/bugzilla/show_bug.cgi?id=35122
 */
static void strip_ipv6_scope_id(char *host)
{
	char *scope, *cp;

	/* bbox wget actually handles IPv6 addresses without [], like
	 * wget "http://::1/xxx", but this is not standard.
	 * To save code, _here_ we do not support it. */

	if (host[0] != '[')
		return; /* not IPv6 */

	scope = strchr(host, '%');
	if (!scope)
		return;

	/* Remove the IPv6 zone identifier from the host address */
	cp = strchr(host, ']');
	if (!cp || (cp[1] != ':' && cp[1] != '\0')) {
		/* malformed address (not "[xx]:nn" or "[xx]") */
		return;
	}

	/* cp points to "]...", scope points to "%eth0]..." */
	overlapping_strcpy(scope, cp);
}

/* Read NMEMB bytes into PTR from STREAM.  Returns the number of bytes read,
 * and a short count if an eof or non-interrupt error is encountered.  */
static size_t safe_fread(void *ptr, size_t nmemb, FILE *stream)
{
	size_t ret;
	char *p = (char*)ptr;

	do {
		clearerr(stream);
		errno = 0;
		ret = fread(p, 1, nmemb, stream);
		p += ret;
		nmemb -= ret;
	} while (nmemb && ferror(stream) && errno == EINTR);

	return p - (char*)ptr;
}

/* Read a line or SIZE-1 bytes into S, whichever is less, from STREAM.
 * Returns S, or NULL if an eof or non-interrupt error is encountered.  */
static char *safe_fgets(char *s, int size, FILE *stream)
{
	char *ret;

	do {
		clearerr(stream);
		errno = 0;
		ret = fgets(s, size, stream);
	} while (ret == NULL && ferror(stream) && errno == EINTR);

	return ret;
}

#if ENABLE_FEATURE_WGET_AUTHENTICATION
/* Base64-encode character string. buf is assumed to be char buf[512]. */
static char *base64enc_512(char buf[512], const char *str)
{
	unsigned len = strlen(str);
	if (len > 512/4*3 - 10) /* paranoia */
		len = 512/4*3 - 10;
	bb_uuencode(buf, str, len, bb_uuenc_tbl_base64);
	return buf;
}
#endif

static char* sanitize_string(char *s)
{
	unsigned char *p = (void *) s;
	while (*p >= ' ')
		p++;
	*p = '\0';
	return s;
}

static FILE *open_socket(len_and_sockaddr *lsa)
{
	FILE *fp;

	/* glibc 2.4 seems to try seeking on it - ??! */
	/* hopefully it understands what ESPIPE means... */
	fp = fdopen(xconnect_stream(lsa), "r+");
	if (fp == NULL)
		bb_perror_msg_and_die("fdopen");

	return fp;
}

static int ftpcmd(const char *s1, const char *s2, FILE *fp, char *buf)
{
	int result;
	if (s1) {
		if (!s2) s2 = "";
		fprintf(fp, "%s%s\r\n", s1, s2);
		fflush(fp);
	}

	do {
		char *buf_ptr;

		if (fgets(buf, 510, fp) == NULL) {
			bb_perror_msg_and_die("error getting response");
		}
		buf_ptr = strstr(buf, "\r\n");
		if (buf_ptr) {
			*buf_ptr = '\0';
		}
	} while (!isdigit(buf[0]) || buf[3] != ' ');

	buf[3] = '\0';
	result = xatoi_u(buf);
	buf[3] = ' ';
	return result;
}

static void parse_url(char *src_url, struct host_info *h)
{
	char *url, *p, *sp;

	/* h->allocated = */ url = xstrdup(src_url);

	if (strncmp(url, "http://", 7) == 0) {
		h->port = bb_lookup_port("http", "tcp", 80);
		h->host = url + 7;
		h->is_ftp = 0;
	} else if (strncmp(url, "ftp://", 6) == 0) {
		h->port = bb_lookup_port("ftp", "tcp", 21);
		h->host = url + 6;
		h->is_ftp = 1;
	} else
		bb_error_msg_and_die("not an http or ftp url: %s", sanitize_string(url));

	// FYI:
	// "Real" wget 'http://busybox.net?var=a/b' sends this request:
	//   'GET /?var=a/b HTTP 1.0'
	//   and saves 'index.html?var=a%2Fb' (we save 'b')
	// wget 'http://busybox.net?login=john@doe':
	//   request: 'GET /?login=john@doe HTTP/1.0'
	//   saves: 'index.html?login=john@doe' (we save '?login=john@doe')
	// wget 'http://busybox.net#test/test':
	//   request: 'GET / HTTP/1.0'
	//   saves: 'index.html' (we save 'test')
	//
	// We also don't add unique .N suffix if file exists...
	sp = strchr(h->host, '/');
	p = strchr(h->host, '?'); if (!sp || (p && sp > p)) sp = p;
	p = strchr(h->host, '#'); if (!sp || (p && sp > p)) sp = p;
	if (!sp) {
		h->path = "";
	} else if (*sp == '/') {
		*sp = '\0';
		h->path = sp + 1;
	} else { // '#' or '?'
		// http://busybox.net?login=john@doe is a valid URL
		// memmove converts to:
		// http:/busybox.nett?login=john@doe...
		memmove(h->host - 1, h->host, sp - h->host);
		h->host--;
		sp[-1] = '\0';
		h->path = sp;
	}

	// We used to set h->user to NULL here, but this interferes
	// with handling of code 302 ("object was moved")

	sp = strrchr(h->host, '@');
	if (sp != NULL) {
		h->user = h->host;
		*sp = '\0';
		h->host = sp + 1;
	}

	sp = h->host;
}

static char *gethdr(char *buf, size_t bufsiz, FILE *fp /*, int *istrunc*/)
{
	char *s, *hdrval;
	int c;

	/* *istrunc = 0; */

	/* retrieve header line */
	if (fgets(buf, bufsiz, fp) == NULL)
		return NULL;

	/* see if we are at the end of the headers */
	for (s = buf; *s == '\r'; ++s)
		continue;
	if (*s == '\n')
		return NULL;

	/* convert the header name to lower case */
	for (s = buf; isalnum(*s) || *s == '-' || *s == '.'; ++s) {
		/* tolower for "A-Z", no-op for "0-9a-z-." */
		*s = (*s | 0x20);
	}

	/* verify we are at the end of the header name */
	if (*s != ':')
		bb_error_msg_and_die("bad header line: %s", sanitize_string(buf));

	/* locate the start of the header value */
	*s++ = '\0';
	hdrval = skip_whitespace(s);

	/* locate the end of header */
	while (*s && *s != '\r' && *s != '\n')
		++s;

	/* end of header found */
	if (*s) {
		*s = '\0';
		return hdrval;
	}

	/* Rats! The buffer isn't big enough to hold the entire header value */
	while (c = getc(fp), c != EOF && c != '\n')
		continue;
	/* *istrunc = 1; */
	return hdrval;
}

#if ENABLE_FEATURE_WGET_LONG_OPTIONS
static char *URL_escape(const char *str)
{
	/* URL encode, see RFC 2396 */
	char *dst;
	char *res = dst = xmalloc(strlen(str) * 3 + 1);
	unsigned char c;

	while (1) {
		c = *str++;
		if (c == '\0'
		/* || strchr("!&'()*-.=_~", c) - more code */
		 || c == '!'
		 || c == '&'
		 || c == '\''
		 || c == '('
		 || c == ')'
		 || c == '*'
		 || c == '-'
		 || c == '.'
		 || c == '='
		 || c == '_'
		 || c == '~'
		 || (c >= '0' && c <= '9')
		 || ((c|0x20) >= 'a' && (c|0x20) <= 'z')
		) {
			*dst++ = c;
			if (c == '\0')
				return res;
		} else {
			*dst++ = '%';
			*dst++ = bb_hexdigits_upcase[c >> 4];
			*dst++ = bb_hexdigits_upcase[c & 0xf];
		}
	}
}
#endif

static FILE* prepare_ftp_session(FILE **dfpp, struct host_info *target, len_and_sockaddr *lsa)
{
	char buf[512];
	FILE *sfp;
	char *str;
	int port;

	if (!target->user)
		target->user = xstrdup("anonymous:busybox@");

	sfp = open_socket(lsa);
	if (ftpcmd(NULL, NULL, sfp, buf) != 220)
		bb_error_msg_and_die("%s", sanitize_string(buf+4));

	/*
	 * Splitting username:password pair,
	 * trying to log in
	 */
	str = strchr(target->user, ':');
	if (str)
		*str++ = '\0';
	switch (ftpcmd("USER ", target->user, sfp, buf)) {
	case 230:
		break;
	case 331:
		if (ftpcmd("PASS ", str, sfp, buf) == 230)
			break;
		/* fall through (failed login) */
	default:
		bb_error_msg_and_die("ftp login: %s", sanitize_string(buf+4));
	}

	ftpcmd("TYPE I", NULL, sfp, buf);

	/*
	 * Querying file size
	 */
	if (ftpcmd("SIZE ", target->path, sfp, buf) == 213) {
		G.content_len = BB_STRTOOFF(buf+4, NULL, 10);
		if (G.content_len < 0 || errno) {
			bb_error_msg_and_die("SIZE value is garbage");
		}
		G.got_clen = 1;
	}

	/*
	 * Entering passive mode
	 */
	if (ftpcmd("PASV", NULL, sfp, buf) != 227) {
 pasv_error:
		bb_error_msg_and_die("bad response to %s: %s", "PASV", sanitize_string(buf));
	}
	// Response is "227 garbageN1,N2,N3,N4,P1,P2[)garbage]
	// Server's IP is N1.N2.N3.N4 (we ignore it)
	// Server's port for data connection is P1*256+P2
	str = strrchr(buf, ')');
	if (str) str[0] = '\0';
	str = strrchr(buf, ',');
	if (!str) goto pasv_error;
	port = xatou_range(str+1, 0, 255);
	*str = '\0';
	str = strrchr(buf, ',');
	if (!str) goto pasv_error;
	port += xatou_range(str+1, 0, 255) * 256;
	set_nport(lsa, htons(port));

	*dfpp = open_socket(lsa);

	if (G.beg_range) {
		sprintf(buf, "REST %"OFF_FMT"u", G.beg_range);
		if (ftpcmd(buf, NULL, sfp, buf) == 350)
			G.content_len -= G.beg_range;
	}

	if (ftpcmd("RETR ", target->path, sfp, buf) > 150)
		bb_error_msg_and_die("bad response to %s: %s", "RETR", sanitize_string(buf));

	return sfp;
}

static void NOINLINE retrieve_file_data(FILE *dfp, int output_fd)
{
	char buf[512];
#if ENABLE_FEATURE_WGET_STATUSBAR || ENABLE_FEATURE_WGET_TIMEOUT
# if ENABLE_FEATURE_WGET_TIMEOUT
	unsigned second_cnt;
# endif
	struct pollfd polldata;

	polldata.fd = fileno(dfp);
	polldata.events = POLLIN | POLLPRI;
	ndelay_on(polldata.fd);
#endif
	progress_meter(PROGRESS_START);

	if (G.chunked)
		goto get_clen;

	/* Loops only if chunked */
	while (1) {
		while (1) {
			int n;
			unsigned rdsz;

			rdsz = sizeof(buf);
			if (G.got_clen) {
				if (G.content_len < (off_t)sizeof(buf)) {
					if ((int)G.content_len <= 0)
						break;
					rdsz = (unsigned)G.content_len;
				}
			}
#if ENABLE_FEATURE_WGET_STATUSBAR || ENABLE_FEATURE_WGET_TIMEOUT
# if ENABLE_FEATURE_WGET_TIMEOUT
			second_cnt = G.timeout_seconds;
# endif
			while (1) {
				if (safe_poll(&polldata, 1, 1000) != 0)
					break; /* error, EOF, or data is available */
# if ENABLE_FEATURE_WGET_TIMEOUT
				if (second_cnt != 0 && --second_cnt == 0) {
					progress_meter(PROGRESS_END);
					bb_perror_msg_and_die("download timed out");
				}
# endif
				/* Needed for "stalled" indicator */
				progress_meter(PROGRESS_BUMP);
			}
#endif
			n = safe_fread(buf, rdsz, dfp);
			if (n <= 0) {
				if (ferror(dfp)) {
					/* perror will not work: ferror doesn't set errno */
					bb_error_msg_and_die(bb_msg_read_error);
				}
				break;
			}
			xwrite(output_fd, buf, n);
#if ENABLE_FEATURE_WGET_STATUSBAR
			G.transferred += n;
			progress_meter(PROGRESS_BUMP);
#endif
			if (G.got_clen)
				G.content_len -= n;
		}

		if (!G.chunked)
			break;

		safe_fgets(buf, sizeof(buf), dfp); /* This is a newline */
 get_clen:
		safe_fgets(buf, sizeof(buf), dfp);
		G.content_len = STRTOOFF(buf, NULL, 16);
		/* FIXME: error check? */
		if (G.content_len == 0)
			break; /* all done! */
		G.got_clen = 1;
	}

	progress_meter(PROGRESS_END);
}

int wget_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int wget_main(int argc UNUSED_PARAM, char **argv)
{
	char buf[512];
	struct host_info server, target;
	len_and_sockaddr *lsa;
	unsigned opt;
	int redir_limit;
	char *proxy = NULL;
	char *dir_prefix = NULL;
#if ENABLE_FEATURE_WGET_LONG_OPTIONS
	char *post_data;
	char *extra_headers = NULL;
	llist_t *headers_llist = NULL;
#endif
	FILE *sfp;                      /* socket to web/ftp server         */
	FILE *dfp;                      /* socket to ftp server (data)      */
	char *fname_out;                /* where to direct output (-O)      */
	int output_fd = -1;
	bool use_proxy;                 /* Use proxies if env vars are set  */
	const char *proxy_flag = "on";  /* Use proxies if env vars are set  */
	const char *user_agent = "Wget";/* "User-Agent" header field        */

	static const char keywords[] ALIGN1 =
		"content-length\0""transfer-encoding\0""chunked\0""location\0";
	enum {
		KEY_content_length = 1, KEY_transfer_encoding, KEY_chunked, KEY_location
	};
#if ENABLE_FEATURE_WGET_LONG_OPTIONS
	static const char wget_longopts[] ALIGN1 =
		/* name, has_arg, val */
		"continue\0"         No_argument       "c"
		"spider\0"           No_argument       "s"
		"quiet\0"            No_argument       "q"
		"output-document\0"  Required_argument "O"
		"directory-prefix\0" Required_argument "P"
		"proxy\0"            Required_argument "Y"
		"user-agent\0"       Required_argument "U"
#if ENABLE_FEATURE_WGET_TIMEOUT
		"timeout\0"          Required_argument "T"
#endif
		/* Ignored: */
		// "tries\0"            Required_argument "t"
		/* Ignored (we always use PASV): */
		"passive-ftp\0"      No_argument       "\xff"
		"header\0"           Required_argument "\xfe"
		"post-data\0"        Required_argument "\xfd"
		/* Ignored (we don't do ssl) */
		"no-check-certificate\0" No_argument   "\xfc"
		;
#endif

	INIT_G();

#if ENABLE_FEATURE_WGET_LONG_OPTIONS
	applet_long_options = wget_longopts;
#endif
	/* server.allocated = target.allocated = NULL; */
	opt_complementary = "-1" IF_FEATURE_WGET_TIMEOUT(":T+") IF_FEATURE_WGET_LONG_OPTIONS(":\xfe::");
	opt = getopt32(argv, "csqO:P:Y:U:T:" /*ignored:*/ "t:",
				&fname_out, &dir_prefix,
				&proxy_flag, &user_agent,
				IF_FEATURE_WGET_TIMEOUT(&G.timeout_seconds) IF_NOT_FEATURE_WGET_TIMEOUT(NULL),
				NULL /* -t RETRIES */
				IF_FEATURE_WGET_LONG_OPTIONS(, &headers_llist)
				IF_FEATURE_WGET_LONG_OPTIONS(, &post_data)
				);
#if ENABLE_FEATURE_WGET_LONG_OPTIONS
	if (headers_llist) {
		int size = 1;
		char *cp;
		llist_t *ll = headers_llist;
		while (ll) {
			size += strlen(ll->data) + 2;
			ll = ll->link;
		}
		extra_headers = cp = xmalloc(size);
		while (headers_llist) {
			cp += sprintf(cp, "%s\r\n", (char*)llist_pop(&headers_llist));
		}
	}
#endif

	/* TODO: compat issue: should handle "wget URL1 URL2..." */

	target.user = NULL;
	parse_url(argv[optind], &target);

	/* Use the proxy if necessary */
	use_proxy = (strcmp(proxy_flag, "off") != 0);
	if (use_proxy) {
		proxy = getenv(target.is_ftp ? "ftp_proxy" : "http_proxy");
		if (proxy && proxy[0]) {
			server.user = NULL;
			parse_url(proxy, &server);
		} else {
			use_proxy = 0;
		}
	}
	if (!use_proxy) {
		server.port = target.port;
		if (ENABLE_FEATURE_IPV6) {
			server.host = xstrdup(target.host);
		} else {
			server.host = target.host;
		}
	}

	if (ENABLE_FEATURE_IPV6)
		strip_ipv6_scope_id(target.host);

	/* Guess an output filename, if there was no -O FILE */
	if (!(opt & WGET_OPT_OUTNAME)) {
		fname_out = bb_get_last_path_component_nostrip(target.path);
		/* handle "wget http://kernel.org//" */
		if (fname_out[0] == '/' || !fname_out[0])
			fname_out = (char*)"index.html";
		/* -P DIR is considered only if there was no -O FILE */
		if (dir_prefix)
			fname_out = concat_path_file(dir_prefix, fname_out);
	} else {
		if (LONE_DASH(fname_out)) {
			/* -O - */
			output_fd = 1;
			opt &= ~WGET_OPT_CONTINUE;
		}
	}
#if ENABLE_FEATURE_WGET_STATUSBAR
	G.curfile = bb_get_last_path_component_nostrip(fname_out);
#endif

	/* Impossible?
	if ((opt & WGET_OPT_CONTINUE) && !fname_out)
		bb_error_msg_and_die("can't specify continue (-c) without a filename (-O)");
	*/

	/* Determine where to start transfer */
	if (opt & WGET_OPT_CONTINUE) {
		output_fd = open(fname_out, O_WRONLY);
		if (output_fd >= 0) {
			G.beg_range = xlseek(output_fd, 0, SEEK_END);
		}
		/* File doesn't exist. We do not create file here yet.
		 * We are not sure it exists on remove side */
	}

	redir_limit = 5;
 resolve_lsa:
	lsa = xhost2sockaddr(server.host, server.port);
	if (!(opt & WGET_OPT_QUIET)) {
		char *s = xmalloc_sockaddr2dotted(&lsa->u.sa);
		fprintf(stderr, "Connecting to %s (%s)\n", server.host, s);
		free(s);
	}
 establish_session:
	if (use_proxy || !target.is_ftp) {
		/*
		 *  HTTP session
		 */
		char *str;
		int status;

		/* Open socket to http server */
		sfp = open_socket(lsa);

		/* Send HTTP request */
		if (use_proxy) {
			fprintf(sfp, "GET %stp://%s/%s HTTP/1.1\r\n",
				target.is_ftp ? "f" : "ht", target.host,
				target.path);
		} else {
			if (opt & WGET_OPT_POST_DATA)
				fprintf(sfp, "POST /%s HTTP/1.1\r\n", target.path);
			else
				fprintf(sfp, "GET /%s HTTP/1.1\r\n", target.path);
		}

		fprintf(sfp, "Host: %s\r\nUser-Agent: %s\r\n",
			target.host, user_agent);

#if ENABLE_FEATURE_WGET_AUTHENTICATION
		if (target.user) {
			fprintf(sfp, "Proxy-Authorization: Basic %s\r\n"+6,
				base64enc_512(buf, target.user));
		}
		if (use_proxy && server.user) {
			fprintf(sfp, "Proxy-Authorization: Basic %s\r\n",
				base64enc_512(buf, server.user));
		}
#endif

		if (G.beg_range)
			fprintf(sfp, "Range: bytes=%"OFF_FMT"u-\r\n", G.beg_range);
#if ENABLE_FEATURE_WGET_LONG_OPTIONS
		if (extra_headers)
			fputs(extra_headers, sfp);

		if (opt & WGET_OPT_POST_DATA) {
			char *estr = URL_escape(post_data);
			fprintf(sfp, "Content-Type: application/x-www-form-urlencoded\r\n");
			fprintf(sfp, "Content-Length: %u\r\n" "\r\n" "%s",
					(int) strlen(estr), estr);
			/*fprintf(sfp, "Connection: Keep-Alive\r\n\r\n");*/
			/*fprintf(sfp, "%s\r\n", estr);*/
			free(estr);
		} else
#endif
		{ /* If "Connection:" is needed, document why */
			fprintf(sfp, /* "Connection: close\r\n" */ "\r\n");
		}

		/*
		 * Retrieve HTTP response line and check for "200" status code.
		 */
 read_response:
		if (fgets(buf, sizeof(buf), sfp) == NULL)
			bb_error_msg_and_die("no response from server");

		str = buf;
		str = skip_non_whitespace(str);
		str = skip_whitespace(str);
		// FIXME: no error check
		// xatou wouldn't work: "200 OK"
		status = atoi(str);
		switch (status) {
		case 0:
		case 100:
			while (gethdr(buf, sizeof(buf), sfp /*, &n*/) != NULL)
				/* eat all remaining headers */;
			goto read_response;
		case 200:
/*
Response 204 doesn't say "null file", it says "metadata
has changed but data didn't":

"10.2.5 204 No Content
The server has fulfilled the request but does not need to return
an entity-body, and might want to return updated metainformation.
The response MAY include new or updated metainformation in the form
of entity-headers, which if present SHOULD be associated with
the requested variant.

If the client is a user agent, it SHOULD NOT change its document
view from that which caused the request to be sent. This response
is primarily intended to allow input for actions to take place
without causing a change to the user agent's active document view,
although any new or updated metainformation SHOULD be applied
to the document currently in the user agent's active view.

The 204 response MUST NOT include a message-body, and thus
is always terminated by the first empty line after the header fields."

However, in real world it was observed that some web servers
(e.g. Boa/0.94.14rc21) simply use code 204 when file size is zero.
*/
		case 204:
			break;
		case 300:	/* redirection */
		case 301:
		case 302:
		case 303:
			break;
		case 206:
			if (G.beg_range)
				break;
			/* fall through */
		default:
			bb_error_msg_and_die("server returned error: %s", sanitize_string(buf));
		}

		/*
		 * Retrieve HTTP headers.
		 */
		while ((str = gethdr(buf, sizeof(buf), sfp /*, &n*/)) != NULL) {
			/* gethdr converted "FOO:" string to lowercase */
			smalluint key;
			/* strip trailing whitespace */
			char *s = strchrnul(str, '\0') - 1;
			while (s >= str && (*s == ' ' || *s == '\t')) {
				*s = '\0';
				s--;
			}
			key = index_in_strings(keywords, buf) + 1;
			if (key == KEY_content_length) {
				G.content_len = BB_STRTOOFF(str, NULL, 10);
				if (G.content_len < 0 || errno) {
					bb_error_msg_and_die("content-length %s is garbage", sanitize_string(str));
				}
				G.got_clen = 1;
				continue;
			}
			if (key == KEY_transfer_encoding) {
				if (index_in_strings(keywords, str_tolower(str)) + 1 != KEY_chunked)
					bb_error_msg_and_die("transfer encoding '%s' is not supported", sanitize_string(str));
				G.chunked = G.got_clen = 1;
			}
			if (key == KEY_location && status >= 300) {
				if (--redir_limit == 0)
					bb_error_msg_and_die("too many redirections");
				fclose(sfp);
				G.got_clen = 0;
				G.chunked = 0;
				if (str[0] == '/')
					/* free(target.allocated); */
					target.path = /* target.allocated = */ xstrdup(str+1);
					/* lsa stays the same: it's on the same server */
				else {
					parse_url(str, &target);
					if (!use_proxy) {
						server.host = target.host;
						/* strip_ipv6_scope_id(target.host); - no! */
						/* we assume remote never gives us IPv6 addr with scope id */
						server.port = target.port;
						free(lsa);
						goto resolve_lsa;
					} /* else: lsa stays the same: we use proxy */
				}
				goto establish_session;
			}
		}
//		if (status >= 300)
//			bb_error_msg_and_die("bad redirection (no Location: header from server)");

		/* For HTTP, data is pumped over the same connection */
		dfp = sfp;

	} else {
		/*
		 *  FTP session
		 */
		sfp = prepare_ftp_session(&dfp, &target, lsa);
	}

	if (opt & WGET_OPT_SPIDER) {
		if (ENABLE_FEATURE_CLEAN_UP)
			fclose(sfp);
		return EXIT_SUCCESS;
	}

	if (output_fd < 0) {
		int o_flags = O_WRONLY | O_CREAT | O_TRUNC | O_EXCL;
		/* compat with wget: -O FILE can overwrite */
		if (opt & WGET_OPT_OUTNAME)
			o_flags = O_WRONLY | O_CREAT | O_TRUNC;
		output_fd = xopen(fname_out, o_flags);
	}

	retrieve_file_data(dfp, output_fd);
	xclose(output_fd);

	if (dfp != sfp) {
		/* It's ftp. Close it properly */
		fclose(dfp);
		if (ftpcmd(NULL, NULL, sfp, buf) != 226)
			bb_error_msg_and_die("ftp error: %s", sanitize_string(buf+4));
		/* ftpcmd("QUIT", NULL, sfp, buf); - why bother? */
	}

	return EXIT_SUCCESS;
}