1 /* Handling of recursive HTTP retrieving.
2 Copyright (C) 1996-2006 Free Software Foundation, Inc.
4 This file is part of GNU Wget.
6 GNU Wget is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 GNU Wget is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with Wget; if not, write to the Free Software Foundation, Inc.,
18 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 In addition, as a special exception, the Free Software Foundation
21 gives permission to link the code of its release of Wget with the
22 OpenSSL project's "OpenSSL" library (or with modified versions of it
23 that use the same license as the "OpenSSL" library), and distribute
24 the linked executables. You must obey the GNU General Public License
25 in all respects for all of the code used other than "OpenSSL". If you
26 modify this file, you may extend this exception to your version of the
27 file, but you are not obligated to do so. If you do not wish to do
28 so, delete this exception statement from your version. */
37 #endif /* HAVE_UNISTD_H */
53 /* Functions for maintaining the URL queue. */
55 struct queue_element {
56 const char *url; /* the URL to download */
57 const char *referer; /* the referring document */
58 int depth; /* the depth */
59 bool html_allowed; /* whether the document is allowed to
60 be treated as HTML. */
62 struct queue_element *next; /* next element in queue */
66 struct queue_element *head;
67 struct queue_element *tail;
71 /* Create a URL queue. */
73 static struct url_queue *
76 struct url_queue *queue = xnew0 (struct url_queue);
80 /* Delete a URL queue. */
83 url_queue_delete (struct url_queue *queue)
88 /* Enqueue a URL in the queue. The queue is FIFO: the items will be
89 retrieved ("dequeued") from the queue in the order they were placed
93 url_enqueue (struct url_queue *queue,
94 const char *url, const char *referer, int depth, bool html_allowed)
96 struct queue_element *qel = xnew (struct queue_element);
98 qel->referer = referer;
100 qel->html_allowed = html_allowed;
104 if (queue->count > queue->maxcount)
105 queue->maxcount = queue->count;
107 DEBUGP (("Enqueuing %s at depth %d\n", url, depth));
108 DEBUGP (("Queue count %d, maxcount %d.\n", queue->count, queue->maxcount));
111 queue->tail->next = qel;
115 queue->head = queue->tail;
118 /* Take a URL out of the queue. Return true if this operation
119 succeeded, or false if the queue is empty. */
122 url_dequeue (struct url_queue *queue,
123 const char **url, const char **referer, int *depth,
126 struct queue_element *qel = queue->head;
131 queue->head = queue->head->next;
136 *referer = qel->referer;
138 *html_allowed = qel->html_allowed;
142 DEBUGP (("Dequeuing %s at depth %d\n", qel->url, qel->depth));
143 DEBUGP (("Queue count %d, maxcount %d.\n", queue->count, queue->maxcount));
149 static bool download_child_p (const struct urlpos *, struct url *, int,
150 struct url *, struct hash_table *);
151 static bool descend_redirect_p (const char *, const char *, int,
152 struct url *, struct hash_table *);
155 /* Retrieve a part of the web beginning with START_URL. This used to
156 be called "recursive retrieval", because the old function was
157 recursive and implemented depth-first search. retrieve_tree on the
158 other hand implements breadth-search traversal of the tree, which
159 results in much nicer ordering of downloads.
161 The algorithm this function uses is simple:
163 1. put START_URL in the queue.
164 2. while there are URLs in the queue:
166 3. get next URL from the queue.
168 5. if the URL is HTML and its depth does not exceed maximum depth,
169 get the list of URLs embedded therein.
170 6. for each of those URLs do the following:
172 7. if the URL is not one of those downloaded before, and if it
173 satisfies the criteria specified by the various command-line
174 options, add it to the queue. */
177 retrieve_tree (const char *start_url)
179 uerr_t status = RETROK;
181 /* The queue of URLs we need to load. */
182 struct url_queue *queue;
184 /* The URLs we do not wish to enqueue, because they are already in
185 the queue, but haven't been downloaded yet. */
186 struct hash_table *blacklist;
189 struct url *start_url_parsed = url_parse (start_url, &up_error_code);
191 if (!start_url_parsed)
193 logprintf (LOG_NOTQUIET, "%s: %s.\n", start_url,
194 url_error (up_error_code));
198 queue = url_queue_new ();
199 blacklist = make_string_hash_table (0);
201 /* Enqueue the starting URL. Use start_url_parsed->url rather than
202 just URL so we enqueue the canonical form of the URL. */
203 url_enqueue (queue, xstrdup (start_url_parsed->url), NULL, 0, true);
204 string_set_add (blacklist, start_url_parsed->url);
208 bool descend = false;
209 char *url, *referer, *file = NULL;
212 bool dash_p_leaf_HTML = false;
214 if (opt.quota && total_downloaded_bytes > opt.quota)
216 if (status == FWRITEERR)
219 /* Get the next URL from the queue... */
221 if (!url_dequeue (queue,
222 (const char **)&url, (const char **)&referer,
223 &depth, &html_allowed))
226 /* ...and download it. Note that this download is in most cases
227 unconditional, as download_child_p already makes sure a file
228 doesn't get enqueued twice -- and yet this check is here, and
229 not in download_child_p. This is so that if you run `wget -r
230 URL1 URL2', and a random URL is encountered once under URL1
231 and again under URL2, but at a different (possibly smaller)
232 depth, we want the URL's children to be taken into account
234 if (dl_url_file_map && hash_table_contains (dl_url_file_map, url))
236 file = xstrdup (hash_table_get (dl_url_file_map, url));
238 DEBUGP (("Already downloaded \"%s\", reusing it from \"%s\".\n",
242 && downloaded_html_set
243 && string_set_contains (downloaded_html_set, file))
249 char *redirected = NULL;
251 status = retrieve_url (url, &file, &redirected, referer, &dt, false);
253 if (html_allowed && file && status == RETROK
254 && (dt & RETROKF) && (dt & TEXTHTML))
259 /* We have been redirected, possibly to another host, or
260 different path, or wherever. Check whether we really
261 want to follow it. */
264 if (!descend_redirect_p (redirected, url, depth,
265 start_url_parsed, blacklist))
268 /* Make sure that the old pre-redirect form gets
270 string_set_add (blacklist, url);
280 visited_url (url, referer);
284 && depth >= opt.reclevel && opt.reclevel != INFINITE_RECURSION)
286 if (opt.page_requisites
287 && (depth == opt.reclevel || depth == opt.reclevel + 1))
289 /* When -p is specified, we are allowed to exceed the
290 maximum depth, but only for the "inline" links,
291 i.e. those that are needed to display the page.
292 Originally this could exceed the depth at most by
293 one, but we allow one more level so that the leaf
294 pages that contain frames can be loaded
296 dash_p_leaf_HTML = true;
300 /* Either -p wasn't specified or it was and we've
301 already spent the two extra (pseudo-)levels that it
302 affords us, so we need to bail out. */
303 DEBUGP (("Not descending further; at depth %d, max. %d.\n",
304 depth, opt.reclevel));
309 /* If the downloaded document was HTML, parse it and enqueue the
310 links it contains. */
314 bool meta_disallow_follow = false;
315 struct urlpos *children
316 = get_urls_html (file, url, &meta_disallow_follow);
318 if (opt.use_robots && meta_disallow_follow)
320 free_urlpos (children);
326 struct urlpos *child = children;
327 struct url *url_parsed = url_parsed = url_parse (url, NULL);
328 assert (url_parsed != NULL);
330 for (; child; child = child->next)
332 if (child->ignore_when_downloading)
334 if (dash_p_leaf_HTML && !child->link_inline_p)
336 if (download_child_p (child, url_parsed, depth, start_url_parsed,
339 url_enqueue (queue, xstrdup (child->url->url),
340 xstrdup (url), depth + 1,
341 child->link_expect_html);
342 /* We blacklist the URL we have enqueued, because we
343 don't want to enqueue (and hence download) the
345 string_set_add (blacklist, child->url->url);
349 url_free (url_parsed);
350 free_urlpos (children);
356 || opt.spider /* opt.recursive is implicitely true */
357 || !acceptable (file)))
359 /* Either --delete-after was specified, or we loaded this
360 (otherwise unneeded because of --spider or rejected by -R)
361 HTML file just to harvest its hyperlinks -- in either case,
362 delete the local file. */
363 DEBUGP (("Removing file due to %s in recursive_retrieve():\n",
364 opt.delete_after ? "--delete-after" :
365 (opt.spider ? "--spider" :
366 "recursive rejection criteria")));
367 logprintf (LOG_VERBOSE,
368 (opt.delete_after || opt.spider
369 ? _("Removing %s.\n")
370 : _("Removing %s since it should be rejected.\n")),
373 logprintf (LOG_NOTQUIET, "unlink: %s\n", strerror (errno));
374 logputs (LOG_VERBOSE, "\n");
375 register_delete_file (file);
379 xfree_null (referer);
383 /* If anything is left of the queue due to a premature exit, free it
389 while (url_dequeue (queue,
390 (const char **)&d1, (const char **)&d2, &d3, &d4))
396 url_queue_delete (queue);
398 if (start_url_parsed)
399 url_free (start_url_parsed);
400 string_set_free (blacklist);
402 if (opt.quota && total_downloaded_bytes > opt.quota)
404 else if (status == FWRITEERR)
410 /* Based on the context provided by retrieve_tree, decide whether a
411 URL is to be descended to. This is only ever called from
412 retrieve_tree, but is in a separate function for clarity.
414 The most expensive checks (such as those for robots) are memoized
415 by storing these URLs to BLACKLIST. This may or may not help. It
416 will help if those URLs are encountered many times. */
419 download_child_p (const struct urlpos *upos, struct url *parent, int depth,
420 struct url *start_url_parsed, struct hash_table *blacklist)
422 struct url *u = upos->url;
423 const char *url = u->url;
424 bool u_scheme_like_http;
426 DEBUGP (("Deciding whether to enqueue \"%s\".\n", url));
428 if (string_set_contains (blacklist, url))
432 char *referrer = url_string (parent, true);
433 DEBUGP (("download_child_p: parent->url is: `%s'\n", parent->url));
434 visited_url (url, referrer);
437 DEBUGP (("Already on the black list.\n"));
441 /* Several things to check for:
442 1. if scheme is not http, and we don't load it
443 2. check for relative links (if relative_only is set)
445 4. check for no-parent
446 5. check for excludes && includes
448 7. check for same host (if spanhost is unset), with possible
449 gethostbyname baggage
450 8. check for robots.txt
452 Addendum: If the URL is FTP, and it is to be loaded, only the
453 domain and suffix settings are "stronger".
455 Note that .html files will get loaded regardless of suffix rules
456 (but that is remedied later with unlink) unless the depth equals
459 More time- and memory- consuming tests should be put later on
462 /* Determine whether URL under consideration has a HTTP-like scheme. */
463 u_scheme_like_http = schemes_are_similar_p (u->scheme, SCHEME_HTTP);
465 /* 1. Schemes other than HTTP are normally not recursed into. */
466 if (!u_scheme_like_http && !(u->scheme == SCHEME_FTP && opt.follow_ftp))
468 DEBUGP (("Not following non-HTTP schemes.\n"));
472 /* 2. If it is an absolute link and they are not followed, throw it
474 if (u_scheme_like_http)
475 if (opt.relative_only && !upos->link_relative_p)
477 DEBUGP (("It doesn't really look like a relative link.\n"));
481 /* 3. If its domain is not to be accepted/looked-up, chuck it
483 if (!accept_domain (u))
485 DEBUGP (("The domain was not accepted.\n"));
489 /* 4. Check for parent directory.
491 If we descended to a different host or changed the scheme, ignore
492 opt.no_parent. Also ignore it for documents needed to display
493 the parent page when in -p mode. */
495 && schemes_are_similar_p (u->scheme, start_url_parsed->scheme)
496 && 0 == strcasecmp (u->host, start_url_parsed->host)
497 && u->port == start_url_parsed->port
498 && !(opt.page_requisites && upos->link_inline_p))
500 if (!subdir_p (start_url_parsed->dir, u->dir))
502 DEBUGP (("Going to \"%s\" would escape \"%s\" with no_parent on.\n",
503 u->dir, start_url_parsed->dir));
508 /* 5. If the file does not match the acceptance list, or is on the
509 rejection list, chuck it out. The same goes for the directory
510 exclusion and inclusion lists. */
511 if (opt.includes || opt.excludes)
513 if (!accdir (u->dir))
515 DEBUGP (("%s (%s) is excluded/not-included.\n", url, u->dir));
520 /* 6. Check for acceptance/rejection rules. We ignore these rules
521 for directories (no file name to match) and for non-leaf HTMLs,
522 which can lead to other files that do need to be downloaded. (-p
523 automatically implies non-leaf because with -p we can, if
524 necesary, overstep the maximum depth to get the page requisites.) */
525 if (u->file[0] != '\0'
526 && !(has_html_suffix_p (u->file)
527 /* The exception only applies to non-leaf HTMLs (but -p
528 always implies non-leaf because we can overstep the
529 maximum depth to get the requisites): */
531 opt.reclevel == INFINITE_RECURSION
533 || depth < opt.reclevel - 1
534 /* -p, which implies non-leaf (see above) */
535 || opt.page_requisites)))
537 if (!acceptable (u->file))
539 DEBUGP (("%s (%s) does not match acc/rej rules.\n",
546 if (schemes_are_similar_p (u->scheme, parent->scheme))
547 if (!opt.spanhost && 0 != strcasecmp (parent->host, u->host))
549 DEBUGP (("This is not the same hostname as the parent's (%s and %s).\n",
550 u->host, parent->host));
555 if (opt.use_robots && u_scheme_like_http)
557 struct robot_specs *specs = res_get_specs (u->host, u->port);
561 if (res_retrieve_file (url, &rfile))
563 specs = res_parse_from_file (rfile);
568 /* If we cannot get real specs, at least produce
569 dummy ones so that we can register them and stop
570 trying to retrieve them. */
571 specs = res_parse ("", 0);
573 res_register_specs (u->host, u->port, specs);
576 /* Now that we have (or don't have) robots.txt specs, we can
577 check what they say. */
578 if (!res_match_path (specs, u->path))
580 DEBUGP (("Not following %s because robots.txt forbids it.\n", url));
581 string_set_add (blacklist, url);
586 /* The URL has passed all the tests. It can be placed in the
588 DEBUGP (("Decided to load it.\n"));
593 DEBUGP (("Decided NOT to load it.\n"));
598 /* This function determines whether we will consider downloading the
599 children of a URL whose download resulted in a redirection,
600 possibly to another host, etc. It is needed very rarely, and thus
601 it is merely a simple-minded wrapper around download_child_p. */
604 descend_redirect_p (const char *redirected, const char *original, int depth,
605 struct url *start_url_parsed, struct hash_table *blacklist)
607 struct url *orig_parsed, *new_parsed;
611 orig_parsed = url_parse (original, NULL);
612 assert (orig_parsed != NULL);
614 new_parsed = url_parse (redirected, NULL);
615 assert (new_parsed != NULL);
617 upos = xnew0 (struct urlpos);
618 upos->url = new_parsed;
620 success = download_child_p (upos, orig_parsed, depth,
621 start_url_parsed, blacklist);
623 url_free (orig_parsed);
624 url_free (new_parsed);
628 DEBUGP (("Redirection \"%s\" failed the test.\n", redirected));