http.c revision 85093 
1/*-
2 * Copyright (c) 2000 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: head/lib/libfetch/http.c 85093 2001-10-18 08:29:26Z des $");
31
32/*
33 * The following copyright applies to the base64 code:
34 *
35 *-
36 * Copyright 1997 Massachusetts Institute of Technology
37 *
38 * Permission to use, copy, modify, and distribute this software and
39 * its documentation for any purpose and without fee is hereby
40 * granted, provided that both the above copyright notice and this
41 * permission notice appear in all copies, that both the above
42 * copyright notice and this permission notice appear in all
43 * supporting documentation, and that the name of M.I.T. not be used
44 * in advertising or publicity pertaining to distribution of the
45 * software without specific, written prior permission.  M.I.T. makes
46 * no representations about the suitability of this software for any
47 * purpose.  It is provided "as is" without express or implied
48 * warranty.
49 *
50 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
51 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
52 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
53 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
54 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
55 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
56 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
57 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
58 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
59 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
60 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
61 * SUCH DAMAGE.
62 */
63
64#include <sys/param.h>
65#include <sys/socket.h>
66
67#include <ctype.h>
68#include <err.h>
69#include <errno.h>
70#include <locale.h>
71#include <netdb.h>
72#include <stdarg.h>
73#include <stdio.h>
74#include <stdlib.h>
75#include <string.h>
76#include <time.h>
77#include <unistd.h>
78
79#include "fetch.h"
80#include "common.h"
81#include "httperr.h"
82
83extern char *__progname; /* XXX not portable */
84
85/* Maximum number of redirects to follow */
86#define MAX_REDIRECT 5
87
88/* Symbolic names for reply codes we care about */
89#define HTTP_OK			200
90#define HTTP_PARTIAL		206
91#define HTTP_MOVED_PERM		301
92#define HTTP_MOVED_TEMP		302
93#define HTTP_SEE_OTHER		303
94#define HTTP_NEED_AUTH		401
95#define HTTP_NEED_PROXY_AUTH	403
96#define HTTP_PROTOCOL_ERROR	999
97
98#define HTTP_REDIRECT(xyz) ((xyz) == HTTP_MOVED_PERM \
99                            || (xyz) == HTTP_MOVED_TEMP \
100                            || (xyz) == HTTP_SEE_OTHER)
101
102
103
104/*****************************************************************************
105 * I/O functions for decoding chunked streams
106 */
107
108struct cookie
109{
110    int		 fd;
111    char	*buf;
112    size_t	 b_size;
113    ssize_t	 b_len;
114    int		 b_pos;
115    int		 eof;
116    int		 error;
117    size_t	 chunksize;
118#ifndef NDEBUG
119    size_t	 total;
120#endif
121};
122
123/*
124 * Get next chunk header
125 */
126static int
127_http_new_chunk(struct cookie *c)
128{
129    char *p;
130
131    if (_fetch_getln(c->fd, &c->buf, &c->b_size, &c->b_len) == -1)
132	return -1;
133
134    if (c->b_len < 2 || !ishexnumber(*c->buf))
135	return -1;
136
137    for (p = c->buf; !isspace(*p) && *p != ';' && p < c->buf + c->b_len; ++p)
138	if (!ishexnumber(*p))
139	    return -1;
140	else if (isdigit(*p))
141	    c->chunksize = c->chunksize * 16 + *p - '0';
142	else
143	    c->chunksize = c->chunksize * 16 + 10 + tolower(*p) - 'a';
144
145#ifndef NDEBUG
146    c->total += c->chunksize;
147    if (c->chunksize == 0)
148	fprintf(stderr, "\033[1m_http_fillbuf(): "
149		"end of last chunk\033[m\n");
150    else
151	fprintf(stderr, "\033[1m_http_fillbuf(): "
152		"new chunk: %lu (%lu)\033[m\n",
153		(unsigned long)c->chunksize, (unsigned long)c->total);
154#endif
155
156    return c->chunksize;
157}
158
159/*
160 * Fill the input buffer, do chunk decoding on the fly
161 */
162static int
163_http_fillbuf(struct cookie *c)
164{
165    if (c->error)
166	return -1;
167    if (c->eof)
168	return 0;
169
170    if (c->chunksize == 0) {
171	switch (_http_new_chunk(c)) {
172	case -1:
173	    c->error = 1;
174	    return -1;
175	case 0:
176	    c->eof = 1;
177	    return 0;
178	}
179    }
180
181    if (c->b_size < c->chunksize) {
182	char *tmp;
183
184	if ((tmp = realloc(c->buf, c->chunksize)) == NULL)
185	    return -1;
186	c->buf = tmp;
187	c->b_size = c->chunksize;
188    }
189
190    if ((c->b_len = read(c->fd, c->buf, c->chunksize)) == -1)
191	return -1;
192    c->chunksize -= c->b_len;
193
194    if (c->chunksize == 0) {
195	char endl[2];
196	read(c->fd, endl, 2);
197    }
198
199    c->b_pos = 0;
200
201    return c->b_len;
202}
203
204/*
205 * Read function
206 */
207static int
208_http_readfn(void *v, char *buf, int len)
209{
210    struct cookie *c = (struct cookie *)v;
211    int l, pos;
212
213    if (c->error)
214	return -1;
215    if (c->eof)
216	return 0;
217
218    for (pos = 0; len > 0; pos += l, len -= l) {
219	/* empty buffer */
220	if (!c->buf || c->b_pos == c->b_len)
221	    if (_http_fillbuf(c) < 1)
222		break;
223	l = c->b_len - c->b_pos;
224	if (len < l)
225	    l = len;
226	bcopy(c->buf + c->b_pos, buf + pos, l);
227	c->b_pos += l;
228    }
229
230    if (!pos && c->error)
231	return -1;
232    return pos;
233}
234
235/*
236 * Write function
237 */
238static int
239_http_writefn(void *v, const char *buf, int len)
240{
241    struct cookie *c = (struct cookie *)v;
242
243    return write(c->fd, buf, len);
244}
245
246/*
247 * Close function
248 */
249static int
250_http_closefn(void *v)
251{
252    struct cookie *c = (struct cookie *)v;
253    int r;
254
255    r = close(c->fd);
256    if (c->buf)
257	free(c->buf);
258    free(c);
259    return r;
260}
261
262/*
263 * Wrap a file descriptor up
264 */
265static FILE *
266_http_funopen(int fd)
267{
268    struct cookie *c;
269    FILE *f;
270
271    if ((c = calloc(1, sizeof *c)) == NULL) {
272	_fetch_syserr();
273	return NULL;
274    }
275    c->fd = fd;
276    if (!(f = funopen(c, _http_readfn, _http_writefn, NULL, _http_closefn))) {
277	_fetch_syserr();
278	free(c);
279	return NULL;
280    }
281    return f;
282}
283
284
285/*****************************************************************************
286 * Helper functions for talking to the server and parsing its replies
287 */
288
289/* Header types */
290typedef enum {
291    hdr_syserror = -2,
292    hdr_error = -1,
293    hdr_end = 0,
294    hdr_unknown = 1,
295    hdr_content_length,
296    hdr_content_range,
297    hdr_last_modified,
298    hdr_location,
299    hdr_transfer_encoding,
300    hdr_www_authenticate
301} hdr_t;
302
303/* Names of interesting headers */
304static struct {
305    hdr_t	 num;
306    const char	*name;
307} hdr_names[] = {
308    { hdr_content_length,	"Content-Length" },
309    { hdr_content_range,	"Content-Range" },
310    { hdr_last_modified,	"Last-Modified" },
311    { hdr_location,		"Location" },
312    { hdr_transfer_encoding,	"Transfer-Encoding" },
313    { hdr_www_authenticate,	"WWW-Authenticate" },
314    { hdr_unknown,		NULL },
315};
316
317static char	*reply_buf;
318static size_t	 reply_size;
319static size_t	 reply_length;
320
321/*
322 * Send a formatted line; optionally echo to terminal
323 */
324static int
325_http_cmd(int fd, const char *fmt, ...)
326{
327    va_list ap;
328    size_t len;
329    char *msg;
330    int r;
331
332    va_start(ap, fmt);
333    len = vasprintf(&msg, fmt, ap);
334    va_end(ap);
335
336    if (msg == NULL) {
337	errno = ENOMEM;
338	_fetch_syserr();
339	return -1;
340    }
341
342    r = _fetch_putln(fd, msg, len);
343    free(msg);
344
345    if (r == -1) {
346	_fetch_syserr();
347	return -1;
348    }
349
350    return 0;
351}
352
353/*
354 * Get and parse status line
355 */
356static int
357_http_get_reply(int fd)
358{
359    char *p;
360
361    if (_fetch_getln(fd, &reply_buf, &reply_size, &reply_length) == -1)
362	return -1;
363    /*
364     * A valid status line looks like "HTTP/m.n xyz reason" where m
365     * and n are the major and minor protocol version numbers and xyz
366     * is the reply code.
367     * Unfortunately, there are servers out there (NCSA 1.5.1, to name
368     * just one) that do not send a version number, so we can't rely
369     * on finding one, but if we do, insist on it being 1.0 or 1.1.
370     * We don't care about the reason phrase.
371     */
372    if (strncmp(reply_buf, "HTTP", 4) != 0)
373	return HTTP_PROTOCOL_ERROR;
374    p = reply_buf + 4;
375    if (*p == '/') {
376	if (p[1] != '1' || p[2] != '.' || (p[3] != '0' && p[3] != '1'))
377	    return HTTP_PROTOCOL_ERROR;
378	p += 4;
379    }
380    if (*p != ' '
381	|| !isdigit(p[1])
382	|| !isdigit(p[2])
383	|| !isdigit(p[3]))
384	return HTTP_PROTOCOL_ERROR;
385
386    return ((p[1] - '0') * 100 + (p[2] - '0') * 10 + (p[3] - '0'));
387}
388
389/*
390 * Check a header; if the type matches the given string, return a
391 * pointer to the beginning of the value.
392 */
393static const char *
394_http_match(const char *str, const char *hdr)
395{
396    while (*str && *hdr && tolower(*str++) == tolower(*hdr++))
397	/* nothing */;
398    if (*str || *hdr != ':')
399	return NULL;
400    while (*hdr && isspace(*++hdr))
401	/* nothing */;
402    return hdr;
403}
404
405/*
406 * Get the next header and return the appropriate symbolic code.
407 */
408static hdr_t
409_http_next_header(int fd, const char **p)
410{
411    int i;
412
413    if (_fetch_getln(fd, &reply_buf, &reply_size, &reply_length) == -1)
414	return hdr_syserror;
415    while (reply_length && isspace(reply_buf[reply_length-1]))
416	reply_length--;
417    reply_buf[reply_length] = 0;
418    if (reply_length == 0)
419	return hdr_end;
420    /*
421     * We could check for malformed headers but we don't really care.
422     * A valid header starts with a token immediately followed by a
423     * colon; a token is any sequence of non-control, non-whitespace
424     * characters except "()<>@,;:\\\"{}".
425     */
426    for (i = 0; hdr_names[i].num != hdr_unknown; i++)
427	if ((*p = _http_match(hdr_names[i].name, reply_buf)) != NULL)
428	    return hdr_names[i].num;
429    return hdr_unknown;
430}
431
432/*
433 * Parse a last-modified header
434 */
435static int
436_http_parse_mtime(const char *p, time_t *mtime)
437{
438    char locale[64], *r;
439    struct tm tm;
440
441    strncpy(locale, setlocale(LC_TIME, NULL), sizeof locale);
442    setlocale(LC_TIME, "C");
443    r = strptime(p, "%a, %d %b %Y %H:%M:%S GMT", &tm);
444    /* XXX should add support for date-2 and date-3 */
445    setlocale(LC_TIME, locale);
446    if (r == NULL)
447	return -1;
448    DEBUG(fprintf(stderr, "last modified: [\033[1m%04d-%02d-%02d "
449		  "%02d:%02d:%02d\033[m]\n",
450		  tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
451		  tm.tm_hour, tm.tm_min, tm.tm_sec));
452    *mtime = timegm(&tm);
453    return 0;
454}
455
456/*
457 * Parse a content-length header
458 */
459static int
460_http_parse_length(const char *p, off_t *length)
461{
462    off_t len;
463
464    for (len = 0; *p && isdigit(*p); ++p)
465	len = len * 10 + (*p - '0');
466    if (*p)
467	return -1;
468    DEBUG(fprintf(stderr, "content length: [\033[1m%lld\033[m]\n",
469		  (long long)len));
470    *length = len;
471    return 0;
472}
473
474/*
475 * Parse a content-range header
476 */
477static int
478_http_parse_range(const char *p, off_t *offset, off_t *length, off_t *size)
479{
480    off_t first, last, len;
481
482    if (strncasecmp(p, "bytes ", 6) != 0)
483	return -1;
484    for (first = 0, p += 6; *p && isdigit(*p); ++p)
485	first = first * 10 + *p - '0';
486    if (*p != '-')
487	return -1;
488    for (last = 0, ++p; *p && isdigit(*p); ++p)
489	last = last * 10 + *p - '0';
490    if (first > last || *p != '/')
491	return -1;
492    for (len = 0, ++p; *p && isdigit(*p); ++p)
493	len = len * 10 + *p - '0';
494    if (*p || len < last - first + 1)
495	return -1;
496    DEBUG(fprintf(stderr, "content range: [\033[1m%lld-%lld/%lld\033[m]\n",
497		  (long long)first, (long long)last, (long long)len));
498    *offset = first;
499    *length = last - first + 1;
500    *size = len;
501    return 0;
502}
503
504
505/*****************************************************************************
506 * Helper functions for authorization
507 */
508
509/*
510 * Base64 encoding
511 */
512static char *
513_http_base64(char *src)
514{
515    static const char base64[] =
516	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
517	"abcdefghijklmnopqrstuvwxyz"
518	"0123456789+/";
519    char *str, *dst;
520    size_t l;
521    int t, r;
522
523    l = strlen(src);
524    if ((str = malloc(((l + 2) / 3) * 4)) == NULL)
525	return NULL;
526    dst = str;
527    r = 0;
528
529    while (l >= 3) {
530	t = (src[0] << 16) | (src[1] << 8) | src[2];
531	dst[0] = base64[(t >> 18) & 0x3f];
532	dst[1] = base64[(t >> 12) & 0x3f];
533	dst[2] = base64[(t >> 6) & 0x3f];
534	dst[3] = base64[(t >> 0) & 0x3f];
535	src += 3; l -= 3;
536	dst += 4; r += 4;
537    }
538
539    switch (l) {
540    case 2:
541	t = (src[0] << 16) | (src[1] << 8);
542	dst[0] = base64[(t >> 18) & 0x3f];
543	dst[1] = base64[(t >> 12) & 0x3f];
544	dst[2] = base64[(t >> 6) & 0x3f];
545	dst[3] = '=';
546	dst += 4;
547	r += 4;
548	break;
549    case 1:
550	t = src[0] << 16;
551	dst[0] = base64[(t >> 18) & 0x3f];
552	dst[1] = base64[(t >> 12) & 0x3f];
553	dst[2] = dst[3] = '=';
554	dst += 4;
555	r += 4;
556	break;
557    case 0:
558	break;
559    }
560
561    *dst = 0;
562    return str;
563}
564
565/*
566 * Encode username and password
567 */
568static int
569_http_basic_auth(int fd, const char *hdr, const char *usr, const char *pwd)
570{
571    char *upw, *auth;
572    int r;
573
574    DEBUG(fprintf(stderr, "usr: [\033[1m%s\033[m]\n", usr));
575    DEBUG(fprintf(stderr, "pwd: [\033[1m%s\033[m]\n", pwd));
576    if (asprintf(&upw, "%s:%s", usr, pwd) == -1)
577	return -1;
578    auth = _http_base64(upw);
579    free(upw);
580    if (auth == NULL)
581	return -1;
582    r = _http_cmd(fd, "%s: Basic %s", hdr, auth);
583    free(auth);
584    return r;
585}
586
587/*
588 * Send an authorization header
589 */
590static int
591_http_authorize(int fd, const char *hdr, const char *p)
592{
593    /* basic authorization */
594    if (strncasecmp(p, "basic:", 6) == 0) {
595	char *user, *pwd, *str;
596	int r;
597
598	/* skip realm */
599	for (p += 6; *p && *p != ':'; ++p)
600	    /* nothing */ ;
601	if (!*p || strchr(++p, ':') == NULL)
602	    return -1;
603	if ((str = strdup(p)) == NULL)
604	    return -1; /* XXX */
605	user = str;
606	pwd = strchr(str, ':');
607	*pwd++ = '\0';
608	r = _http_basic_auth(fd, hdr, user, pwd);
609	free(str);
610	return r;
611    }
612    return -1;
613}
614
615
616/*****************************************************************************
617 * Helper functions for connecting to a server or proxy
618 */
619
620/*
621 * Connect to the correct HTTP server or proxy.
622 */
623static int
624_http_connect(struct url *URL, struct url *purl, const char *flags)
625{
626    int verbose;
627    int af, fd;
628
629#ifdef INET6
630    af = AF_UNSPEC;
631#else
632    af = AF_INET;
633#endif
634
635    verbose = CHECK_FLAG('v');
636    if (CHECK_FLAG('4'))
637	af = AF_INET;
638#ifdef INET6
639    else if (CHECK_FLAG('6'))
640	af = AF_INET6;
641#endif
642
643    if (purl) {
644	URL = purl;
645    } else if (strcasecmp(URL->scheme, SCHEME_FTP) == 0) {
646	/* can't talk http to an ftp server */
647	/* XXX should set an error code */
648	return -1;
649    }
650
651    if ((fd = _fetch_connect(URL->host, URL->port, af, verbose)) == -1)
652	/* _fetch_connect() has already set an error code */
653	return -1;
654    return fd;
655}
656
657static struct url *
658_http_get_proxy(void)
659{
660    struct url *purl;
661    char *p;
662
663    if (((p = getenv("HTTP_PROXY")) || (p = getenv("http_proxy"))) &&
664	(purl = fetchParseURL(p))) {
665	if (!*purl->scheme)
666	    strcpy(purl->scheme, SCHEME_HTTP);
667	if (!purl->port)
668	    purl->port = _fetch_default_proxy_port(purl->scheme);
669	if (strcasecmp(purl->scheme, SCHEME_HTTP) == 0)
670	    return purl;
671	fetchFreeURL(purl);
672    }
673    return NULL;
674}
675
676
677/*****************************************************************************
678 * Core
679 */
680
681/*
682 * Send a request and process the reply
683 */
684FILE *
685_http_request(struct url *URL, const char *op, struct url_stat *us,
686	      struct url *purl, const char *flags)
687{
688    struct url *url, *new;
689    int chunked, direct, need_auth, noredirect, verbose;
690    int code, fd, i, n;
691    off_t offset, clength, length, size;
692    time_t mtime;
693    const char *p;
694    FILE *f;
695    hdr_t h;
696    char *host;
697#ifdef INET6
698    char hbuf[MAXHOSTNAMELEN + 1];
699#endif
700
701    direct = CHECK_FLAG('d');
702    noredirect = CHECK_FLAG('A');
703    verbose = CHECK_FLAG('v');
704
705    if (direct && purl) {
706	fetchFreeURL(purl);
707	purl = NULL;
708    }
709
710    /* try the provided URL first */
711    url = URL;
712
713    /* if the A flag is set, we only get one try */
714    n = noredirect ? 1 : MAX_REDIRECT;
715    i = 0;
716
717    need_auth = 0;
718    do {
719	new = NULL;
720	chunked = 0;
721	offset = 0;
722	clength = -1;
723	length = -1;
724	size = -1;
725	mtime = 0;
726
727	/* check port */
728	if (!url->port)
729	    url->port = _fetch_default_port(url->scheme);
730
731	/* connect to server or proxy */
732	if ((fd = _http_connect(url, purl, flags)) == -1)
733	    goto ouch;
734
735	host = url->host;
736#ifdef INET6
737	if (strchr(url->host, ':')) {
738	    snprintf(hbuf, sizeof(hbuf), "[%s]", url->host);
739	    host = hbuf;
740	}
741#endif
742
743	/* send request */
744	if (verbose)
745	    _fetch_info("requesting %s://%s:%d%s",
746			url->scheme, host, url->port, url->doc);
747	if (purl) {
748	    _http_cmd(fd, "%s %s://%s:%d%s HTTP/1.1",
749		      op, url->scheme, host, url->port, url->doc);
750	} else {
751	    _http_cmd(fd, "%s %s HTTP/1.1",
752		      op, url->doc);
753	}
754
755	/* virtual host */
756	if (url->port == _fetch_default_port(url->scheme))
757	    _http_cmd(fd, "Host: %s", host);
758	else
759	    _http_cmd(fd, "Host: %s:%d", host, url->port);
760
761	/* proxy authorization */
762	if (purl) {
763	    if (*purl->user || *purl->pwd)
764		_http_basic_auth(fd, "Proxy-Authorization",
765				 purl->user, purl->pwd);
766	    else if ((p = getenv("HTTP_PROXY_AUTH")) != NULL && *p != '\0')
767		_http_authorize(fd, "Proxy-Authorization", p);
768	}
769
770	/* server authorization */
771	if (need_auth || *url->user || *url->pwd) {
772	    if (*url->user || *url->pwd)
773		_http_basic_auth(fd, "Authorization", url->user, url->pwd);
774	    else if ((p = getenv("HTTP_AUTH")) != NULL && *p != '\0')
775		_http_authorize(fd, "Authorization", p);
776	    else if (fetchAuthMethod && fetchAuthMethod(url) == 0) {
777		_http_basic_auth(fd, "Authorization", url->user, url->pwd);
778	    } else {
779		_http_seterr(HTTP_NEED_AUTH);
780		goto ouch;
781	    }
782	}
783
784	/* other headers */
785	if ((p = getenv("HTTP_USER_AGENT")) != NULL && *p != '\0')
786	    _http_cmd(fd, "User-Agent: %s", p);
787	else
788	    _http_cmd(fd, "User-Agent: %s " _LIBFETCH_VER, __progname);
789	if (url->offset)
790	    _http_cmd(fd, "Range: bytes=%lld-", (long long)url->offset);
791	_http_cmd(fd, "Connection: close");
792	_http_cmd(fd, "");
793
794	/* get reply */
795	switch ((code = _http_get_reply(fd))) {
796	case HTTP_OK:
797	case HTTP_PARTIAL:
798	    /* fine */
799	    break;
800	case HTTP_MOVED_PERM:
801	case HTTP_MOVED_TEMP:
802	    /*
803	     * Not so fine, but we still have to read the headers to
804	     * get the new location.
805	     */
806	    break;
807	case HTTP_NEED_AUTH:
808	    if (need_auth) {
809		/*
810		 * We already sent out authorization code, so there's
811		 * nothing more we can do.
812		 */
813		_http_seterr(code);
814		goto ouch;
815	    }
816	    /* try again, but send the password this time */
817	    if (verbose)
818		_fetch_info("server requires authorization");
819	    break;
820	case HTTP_NEED_PROXY_AUTH:
821	    /*
822	     * If we're talking to a proxy, we already sent our proxy
823	     * authorization code, so there's nothing more we can do.
824	     */
825	    _http_seterr(code);
826	    goto ouch;
827	case HTTP_PROTOCOL_ERROR:
828	    /* fall through */
829	case -1:
830	    _fetch_syserr();
831	    goto ouch;
832	default:
833	    _http_seterr(code);
834	    goto ouch;
835	}
836
837	/* get headers */
838	do {
839	    switch ((h = _http_next_header(fd, &p))) {
840	    case hdr_syserror:
841		_fetch_syserr();
842		goto ouch;
843	    case hdr_error:
844		_http_seterr(HTTP_PROTOCOL_ERROR);
845		goto ouch;
846	    case hdr_content_length:
847		_http_parse_length(p, &clength);
848		break;
849	    case hdr_content_range:
850		_http_parse_range(p, &offset, &length, &size);
851		break;
852	    case hdr_last_modified:
853		_http_parse_mtime(p, &mtime);
854		break;
855	    case hdr_location:
856		if (!HTTP_REDIRECT(code))
857		    break;
858		if (new)
859		    free(new);
860		if (verbose)
861		    _fetch_info("%d redirect to %s", code, p);
862		if (*p == '/')
863		    /* absolute path */
864		    new = fetchMakeURL(url->scheme, url->host, url->port, p,
865				       url->user, url->pwd);
866		else
867		    new = fetchParseURL(p);
868		if (new == NULL) {
869		    /* XXX should set an error code */
870		    DEBUG(fprintf(stderr, "failed to parse new URL\n"));
871		    goto ouch;
872		}
873		if (!*new->user && !*new->pwd) {
874		    strcpy(new->user, url->user);
875		    strcpy(new->pwd, url->pwd);
876		}
877		new->offset = url->offset;
878		new->length = url->length;
879		break;
880	    case hdr_transfer_encoding:
881		/* XXX weak test*/
882		chunked = (strcasecmp(p, "chunked") == 0);
883		break;
884	    case hdr_www_authenticate:
885		if (code != HTTP_NEED_AUTH)
886		    break;
887		/* if we were smarter, we'd check the method and realm */
888		break;
889	    case hdr_end:
890		/* fall through */
891	    case hdr_unknown:
892		/* ignore */
893		break;
894	    }
895	} while (h > hdr_end);
896
897	/* we have a hit */
898	if (code == HTTP_OK || code == HTTP_PARTIAL)
899	    break;
900
901	/* we need to provide authentication */
902	if (code == HTTP_NEED_AUTH) {
903	    need_auth = 1;
904	    close(fd);
905	    fd = -1;
906	    continue;
907	}
908
909	/* all other cases: we got a redirect */
910	need_auth = 0;
911	close(fd);
912	fd = -1;
913	if (!new) {
914	    DEBUG(fprintf(stderr, "redirect with no new location\n"));
915	    break;
916	}
917	if (url != URL)
918	    fetchFreeURL(url);
919	url = new;
920    } while (++i < n);
921
922    /* we failed, or ran out of retries */
923    if (fd == -1) {
924	_http_seterr(code);
925	goto ouch;
926    }
927
928    DEBUG(fprintf(stderr, "offset %lld, length %lld,"
929		  " size %lld, clength %lld\n",
930		  (long long)offset, (long long)length,
931		  (long long)size, (long long)clength));
932
933    /* check for inconsistencies */
934    if (clength != -1 && length != -1 && clength != length) {
935	_http_seterr(HTTP_PROTOCOL_ERROR);
936	goto ouch;
937    }
938    if (clength == -1)
939	clength = length;
940    if (clength != -1)
941	length = offset + clength;
942    if (length != -1 && size != -1 && length != size) {
943	_http_seterr(HTTP_PROTOCOL_ERROR);
944	goto ouch;
945    }
946    if (size == -1)
947	size = length;
948
949    /* fill in stats */
950    if (us) {
951	us->size = size;
952	us->atime = us->mtime = mtime;
953    }
954
955    /* too far? */
956    if (offset > URL->offset) {
957	_http_seterr(HTTP_PROTOCOL_ERROR);
958	goto ouch;
959    }
960
961    /* report back real offset and size */
962    URL->offset = offset;
963    URL->length = clength;
964
965    /* wrap it up in a FILE */
966    if ((f = chunked ? _http_funopen(fd) : fdopen(fd, "r")) == NULL) {
967	_fetch_syserr();
968	goto ouch;
969    }
970
971    if (url != URL)
972	fetchFreeURL(url);
973    if (purl)
974	fetchFreeURL(purl);
975
976    return f;
977
978 ouch:
979    if (url != URL)
980	fetchFreeURL(url);
981    if (purl)
982	fetchFreeURL(purl);
983    if (fd != -1)
984	close(fd);
985    return NULL;
986}
987
988
989/*****************************************************************************
990 * Entry points
991 */
992
993/*
994 * Retrieve and stat a file by HTTP
995 */
996FILE *
997fetchXGetHTTP(struct url *URL, struct url_stat *us, const char *flags)
998{
999    return _http_request(URL, "GET", us, _http_get_proxy(), flags);
1000}
1001
1002/*
1003 * Retrieve a file by HTTP
1004 */
1005FILE *
1006fetchGetHTTP(struct url *URL, const char *flags)
1007{
1008    return fetchXGetHTTP(URL, NULL, flags);
1009}
1010
1011/*
1012 * Store a file by HTTP
1013 */
1014FILE *
1015fetchPutHTTP(struct url *URL __unused, const char *flags __unused)
1016{
1017    warnx("fetchPutHTTP(): not implemented");
1018    return NULL;
1019}
1020
1021/*
1022 * Get an HTTP document's metadata
1023 */
1024int
1025fetchStatHTTP(struct url *URL, struct url_stat *us, const char *flags)
1026{
1027    FILE *f;
1028
1029    if ((f = _http_request(URL, "HEAD", us, _http_get_proxy(), flags)) == NULL)
1030	return -1;
1031    fclose(f);
1032    return 0;
1033}
1034
1035/*
1036 * List a directory
1037 */
1038struct url_ent *
1039fetchListHTTP(struct url *url __unused, const char *flags __unused)
1040{
1041    warnx("fetchListHTTP(): not implemented");
1042    return NULL;
1043}
1044