1 /* Handling of recursive HTTP retrieving.
2 Copyright (C) 1996-2005 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 */
52 /* Functions for maintaining the URL queue. */
54 struct queue_element {
55 const char *url; /* the URL to download */
56 const char *referer; /* the referring document */
57 int depth; /* the depth */
58 bool html_allowed; /* whether the document is allowed to
59 be treated as HTML. */
61 struct queue_element *next; /* next element in queue */
65 struct queue_element *head;
66 struct queue_element *tail;
70 /* Create a URL queue. */
72 static struct url_queue *
75 struct url_queue *queue = xnew0 (struct url_queue);
79 /* Delete a URL queue. */
82 url_queue_delete (struct url_queue *queue)
87 /* Enqueue a URL in the queue. The queue is FIFO: the items will be
88 retrieved ("dequeued") from the queue in the order they were placed
92 url_enqueue (struct url_queue *queue,
93 const char *url, const char *referer, int depth, bool html_allowed)
95 struct queue_element *qel = xnew (struct queue_element);
97 qel->referer = referer;
99 qel->html_allowed = html_allowed;
103 if (queue->count > queue->maxcount)
104 queue->maxcount = queue->count;
106 DEBUGP (("Enqueuing %s at depth %d\n", url, depth));
107 DEBUGP (("Queue count %d, maxcount %d.\n", queue->count, queue->maxcount));
110 queue->tail->next = qel;
114 queue->head = queue->tail;
117 /* Take a URL out of the queue. Return true if this operation
118 succeeded, or false if the queue is empty. */
121 url_dequeue (struct url_queue *queue,
122 const char **url, const char **referer, int *depth,
125 struct queue_element *qel = queue->head;
130 queue->head = queue->head->next;
135 *referer = qel->referer;
137 *html_allowed = qel->html_allowed;
141 DEBUGP (("Dequeuing %s at depth %d\n", qel->url, qel->depth));
142 DEBUGP (("Queue count %d, maxcount %d.\n", queue->count, queue->maxcount));
148 static bool download_child_p (const struct urlpos *, struct url *, int,
149 struct url *, struct hash_table *);
150 static bool descend_redirect_p (const char *, const char *, int,
151 struct url *, struct hash_table *);
154 /* Retrieve a part of the web beginning with START_URL. This used to
155 be called "recursive retrieval", because the old function was
156 recursive and implemented depth-first search. retrieve_tree on the
157 other hand implements breadth-search traversal of the tree, which
158 results in much nicer ordering of downloads.
160 The algorithm this function uses is simple:
162 1. put START_URL in the queue.
163 2. while there are URLs in the queue:
165 3. get next URL from the queue.
167 5. if the URL is HTML and its depth does not exceed maximum depth,
168 get the list of URLs embedded therein.
169 6. for each of those URLs do the following:
171 7. if the URL is not one of those downloaded before, and if it
172 satisfies the criteria specified by the various command-line
173 options, add it to the queue. */
176 retrieve_tree (const char *start_url)
178 uerr_t status = RETROK;
180 /* The queue of URLs we need to load. */
181 struct url_queue *queue;
183 /* The URLs we do not wish to enqueue, because they are already in
184 the queue, but haven't been downloaded yet. */
185 struct hash_table *blacklist;
188 struct url *start_url_parsed = url_parse (start_url, &up_error_code);
190 if (!start_url_parsed)
192 logprintf (LOG_NOTQUIET, "%s: %s.\n", start_url,
193 url_error (up_error_code));
197 queue = url_queue_new ();
198 blacklist = make_string_hash_table (0);
200 /* Enqueue the starting URL. Use start_url_parsed->url rather than
201 just URL so we enqueue the canonical form of the URL. */
202 url_enqueue (queue, xstrdup (start_url_parsed->url), NULL, 0, true);
203 string_set_add (blacklist, start_url_parsed->url);
207 bool descend = false;
208 char *url, *referer, *file = NULL;
211 bool dash_p_leaf_HTML = false;
213 if (opt.quota && total_downloaded_bytes > opt.quota)
215 if (status == FWRITEERR)
218 /* Get the next URL from the queue... */
220 if (!url_dequeue (queue,
221 (const char **)&url, (const char **)&referer,
222 &depth, &html_allowed))
225 /* ...and download it. Note that this download is in most cases
226 unconditional, as download_child_p already makes sure a file
227 doesn't get enqueued twice -- and yet this check is here, and
228 not in download_child_p. This is so that if you run `wget -r
229 URL1 URL2', and a random URL is encountered once under URL1
230 and again under URL2, but at a different (possibly smaller)
231 depth, we want the URL's children to be taken into account
233 if (dl_url_file_map && hash_table_contains (dl_url_file_map, url))
235 file = xstrdup (hash_table_get (dl_url_file_map, url));
237 DEBUGP (("Already downloaded \"%s\", reusing it from \"%s\".\n",
241 && downloaded_html_set
242 && string_set_contains (downloaded_html_set, file))
248 char *redirected = NULL;
250 status = retrieve_url (url, &file, &redirected, referer, &dt, false);
252 if (html_allowed && file && status == RETROK
253 && (dt & RETROKF) && (dt & TEXTHTML))
258 /* We have been redirected, possibly to another host, or
259 different path, or wherever. Check whether we really
260 want to follow it. */
263 if (!descend_redirect_p (redirected, url, depth,
264 start_url_parsed, blacklist))
267 /* Make sure that the old pre-redirect form gets
269 string_set_add (blacklist, url);
278 && depth >= opt.reclevel && opt.reclevel != INFINITE_RECURSION)
280 if (opt.page_requisites
281 && (depth == opt.reclevel || depth == opt.reclevel + 1))
283 /* When -p is specified, we are allowed to exceed the
284 maximum depth, but only for the "inline" links,
285 i.e. those that are needed to display the page.
286 Originally this could exceed the depth at most by
287 one, but we allow one more level so that the leaf
288 pages that contain frames can be loaded
290 dash_p_leaf_HTML = true;
294 /* Either -p wasn't specified or it was and we've
295 already spent the two extra (pseudo-)levels that it
296 affords us, so we need to bail out. */
297 DEBUGP (("Not descending further; at depth %d, max. %d.\n",
298 depth, opt.reclevel));
303 /* If the downloaded document was HTML, parse it and enqueue the
304 links it contains. */
308 bool meta_disallow_follow = false;
309 struct urlpos *children
310 = get_urls_html (file, url, &meta_disallow_follow);
312 if (opt.use_robots && meta_disallow_follow)
314 free_urlpos (children);
320 struct urlpos *child = children;
321 struct url *url_parsed = url_parsed = url_parse (url, NULL);
322 assert (url_parsed != NULL);
324 for (; child; child = child->next)
326 if (child->ignore_when_downloading)
328 if (dash_p_leaf_HTML && !child->link_inline_p)
330 if (download_child_p (child, url_parsed, depth, start_url_parsed,
333 url_enqueue (queue, xstrdup (child->url->url),
334 xstrdup (url), depth + 1,
335 child->link_expect_html);
336 /* We blacklist the URL we have enqueued, because we
337 don't want to enqueue (and hence download) the
339 string_set_add (blacklist, child->url->url);
343 url_free (url_parsed);
344 free_urlpos (children);
350 || opt.spider /* opt.recursive is implicitely true */
351 || !acceptable (file)))
353 /* Either --delete-after was specified, or we loaded this
354 (otherwise unneeded because of --spider or rejected by -R)
355 HTML file just to harvest its hyperlinks -- in either case,
356 delete the local file. */
357 DEBUGP (("Removing file due to %s in recursive_retrieve():\n",
358 opt.delete_after ? "--delete-after" :
359 (opt.spider ? "--spider" :
360 "recursive rejection criteria")));
361 logprintf (LOG_VERBOSE,
362 (opt.delete_after || opt.spider
363 ? _("Removing %s.\n")
364 : _("Removing %s since it should be rejected.\n")),
367 logprintf (LOG_NOTQUIET, "unlink: %s\n", strerror (errno));
368 register_delete_file (file);
372 xfree_null (referer);
376 /* If anything is left of the queue due to a premature exit, free it
382 while (url_dequeue (queue,
383 (const char **)&d1, (const char **)&d2, &d3, &d4))
389 url_queue_delete (queue);
391 if (start_url_parsed)
392 url_free (start_url_parsed);
393 string_set_free (blacklist);
395 if (opt.quota && total_downloaded_bytes > opt.quota)
397 else if (status == FWRITEERR)
403 /* Based on the context provided by retrieve_tree, decide whether a
404 URL is to be descended to. This is only ever called from
405 retrieve_tree, but is in a separate function for clarity.
407 The most expensive checks (such as those for robots) are memoized
408 by storing these URLs to BLACKLIST. This may or may not help. It
409 will help if those URLs are encountered many times. */
412 download_child_p (const struct urlpos *upos, struct url *parent, int depth,
413 struct url *start_url_parsed, struct hash_table *blacklist)
415 struct url *u = upos->url;
416 const char *url = u->url;
417 bool u_scheme_like_http;
419 DEBUGP (("Deciding whether to enqueue \"%s\".\n", url));
421 if (string_set_contains (blacklist, url))
423 DEBUGP (("Already on the black list.\n"));
427 /* Several things to check for:
428 1. if scheme is not http, and we don't load it
429 2. check for relative links (if relative_only is set)
431 4. check for no-parent
432 5. check for excludes && includes
434 7. check for same host (if spanhost is unset), with possible
435 gethostbyname baggage
436 8. check for robots.txt
438 Addendum: If the URL is FTP, and it is to be loaded, only the
439 domain and suffix settings are "stronger".
441 Note that .html files will get loaded regardless of suffix rules
442 (but that is remedied later with unlink) unless the depth equals
445 More time- and memory- consuming tests should be put later on
448 /* Determine whether URL under consideration has a HTTP-like scheme. */
449 u_scheme_like_http = schemes_are_similar_p (u->scheme, SCHEME_HTTP);
451 /* 1. Schemes other than HTTP are normally not recursed into. */
452 if (!u_scheme_like_http && !(u->scheme == SCHEME_FTP && opt.follow_ftp))
454 DEBUGP (("Not following non-HTTP schemes.\n"));
458 /* 2. If it is an absolute link and they are not followed, throw it
460 if (u_scheme_like_http)
461 if (opt.relative_only && !upos->link_relative_p)
463 DEBUGP (("It doesn't really look like a relative link.\n"));
467 /* 3. If its domain is not to be accepted/looked-up, chuck it
469 if (!accept_domain (u))
471 DEBUGP (("The domain was not accepted.\n"));
475 /* 4. Check for parent directory.
477 If we descended to a different host or changed the scheme, ignore
478 opt.no_parent. Also ignore it for documents needed to display
479 the parent page when in -p mode. */
481 && schemes_are_similar_p (u->scheme, start_url_parsed->scheme)
482 && 0 == strcasecmp (u->host, start_url_parsed->host)
483 && u->port == start_url_parsed->port
484 && !(opt.page_requisites && upos->link_inline_p))
486 if (!subdir_p (start_url_parsed->dir, u->dir))
488 DEBUGP (("Going to \"%s\" would escape \"%s\" with no_parent on.\n",
489 u->dir, start_url_parsed->dir));
494 /* 5. If the file does not match the acceptance list, or is on the
495 rejection list, chuck it out. The same goes for the directory
496 exclusion and inclusion lists. */
497 if (opt.includes || opt.excludes)
499 if (!accdir (u->dir))
501 DEBUGP (("%s (%s) is excluded/not-included.\n", url, u->dir));
506 /* 6. Check for acceptance/rejection rules. We ignore these rules
507 for directories (no file name to match) and for non-leaf HTMLs,
508 which can lead to other files that do need to be downloaded. (-p
509 automatically implies non-leaf because with -p we can, if
510 necesary, overstep the maximum depth to get the page requisites.) */
511 if (u->file[0] != '\0'
512 && !(has_html_suffix_p (u->file)
513 /* The exception only applies to non-leaf HTMLs (but -p
514 always implies non-leaf because we can overstep the
515 maximum depth to get the requisites): */
517 opt.reclevel == INFINITE_RECURSION
519 || depth < opt.reclevel - 1
520 /* -p, which implies non-leaf (see above) */
521 || opt.page_requisites)))
523 if (!acceptable (u->file))
525 DEBUGP (("%s (%s) does not match acc/rej rules.\n",
532 if (schemes_are_similar_p (u->scheme, parent->scheme))
533 if (!opt.spanhost && 0 != strcasecmp (parent->host, u->host))
535 DEBUGP (("This is not the same hostname as the parent's (%s and %s).\n",
536 u->host, parent->host));
541 if (opt.use_robots && u_scheme_like_http)
543 struct robot_specs *specs = res_get_specs (u->host, u->port);
547 if (res_retrieve_file (url, &rfile))
549 specs = res_parse_from_file (rfile);
554 /* If we cannot get real specs, at least produce
555 dummy ones so that we can register them and stop
556 trying to retrieve them. */
557 specs = res_parse ("", 0);
559 res_register_specs (u->host, u->port, specs);
562 /* Now that we have (or don't have) robots.txt specs, we can
563 check what they say. */
564 if (!res_match_path (specs, u->path))
566 DEBUGP (("Not following %s because robots.txt forbids it.\n", url));
567 string_set_add (blacklist, url);
572 /* The URL has passed all the tests. It can be placed in the
574 DEBUGP (("Decided to load it.\n"));
579 DEBUGP (("Decided NOT to load it.\n"));
584 /* This function determines whether we will consider downloading the
585 children of a URL whose download resulted in a redirection,
586 possibly to another host, etc. It is needed very rarely, and thus
587 it is merely a simple-minded wrapper around download_child_p. */
590 descend_redirect_p (const char *redirected, const char *original, int depth,
591 struct url *start_url_parsed, struct hash_table *blacklist)
593 struct url *orig_parsed, *new_parsed;
597 orig_parsed = url_parse (original, NULL);
598 assert (orig_parsed != NULL);
600 new_parsed = url_parse (redirected, NULL);
601 assert (new_parsed != NULL);
603 upos = xnew0 (struct urlpos);
604 upos->url = new_parsed;
606 success = download_child_p (upos, orig_parsed, depth,
607 start_url_parsed, blacklist);
609 url_free (orig_parsed);
610 url_free (new_parsed);
614 DEBUGP (("Redirection \"%s\" failed the test.\n", redirected));