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/*

 * Copyright 2006,2007 Daniel Silverstone 

 * Copyright 2007 James Bursa 

 * Copyright 2003 Phil Mellor 

 *

 * This file is part of NetSurf, http://www.netsurf-browser.org/

 *

 * NetSurf is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; version 2 of the License.

 *

 * NetSurf is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see .

 */

/** \file

 * Fetching of data from a URL (implementation).

 *

 * Active fetches are held in the circular linked list ::fetch_ring. There may

 * be at most ::option_max_fetchers_per_host active requests per Host: header.

 * There may be at most ::option_max_fetchers active requests overall. Inactive

 * fetchers are stored in the ::queue_ring waiting for use.

 */

#include 

#include 

#include 

#include 

#include 

#include 

#include 

#include "utils/config.h"

#include "content/fetch.h"

#include "content/fetchers/resource.h"

#include "content/fetchers/about.h"

#include "content/fetchers/curl.h"

#include "content/fetchers/data.h"

#include "content/fetchers/file.h"

#include "content/urldb.h"

#include "desktop/netsurf.h"

#include "desktop/options.h"

#include "utils/log.h"

#include "utils/messages.h"

#include "utils/nsurl.h"

#include "utils/utils.h"

#include "utils/ring.h"

/* Define this to turn on verbose fetch logging */

#undef DEBUG_FETCH_VERBOSE

bool fetch_active;	/**< Fetches in progress, please call fetch_poll(). */

/** Information about a fetcher for a given scheme. */

typedef struct scheme_fetcher_s {

	lwc_string *scheme_name;		/**< The scheme. */

	fetcher_can_fetch can_fetch;		/**< Ensure an URL can be fetched. */

	fetcher_setup_fetch setup_fetch;	/**< Set up a fetch. */

	fetcher_start_fetch start_fetch;	/**< Start a fetch. */

	fetcher_abort_fetch abort_fetch;	/**< Abort a fetch. */

	fetcher_free_fetch free_fetch;		/**< Free a fetch. */

	fetcher_poll_fetcher poll_fetcher;	/**< Poll this fetcher. */

	fetcher_finalise finaliser;		/**< Clean up this fetcher. */

	int refcount;				/**< When zero, clean up the fetcher. */

	struct scheme_fetcher_s *next_fetcher;	/**< Next fetcher in the list. */

	struct scheme_fetcher_s *prev_fetcher;  /**< Prev fetcher in the list. */

} scheme_fetcher;

static scheme_fetcher *fetchers = NULL;

/** Information for a single fetch. */

struct fetch {

	fetch_callback callback;/**< Callback function. */

	nsurl *url;		/**< URL. */

	nsurl *referer;		/**< Referer URL. */

	bool send_referer;	/**< Valid to send the referer */

	bool verifiable;	/**< Transaction is verifiable */

	void *p;		/**< Private data for callback. */

	lwc_string *host;	/**< Host part of URL, interned */

	long http_code;		/**< HTTP response code, or 0. */

	scheme_fetcher *ops;	/**< Fetcher operations for this fetch,

				     NULL if not set. */

	void *fetcher_handle;	/**< The handle for the fetcher. */

	bool fetch_is_active;	/**< This fetch is active. */

	struct fetch *r_prev;	/**< Previous active fetch in ::fetch_ring. */

	struct fetch *r_next;	/**< Next active fetch in ::fetch_ring. */

};

static struct fetch *fetch_ring = 0;	/**< Ring of active fetches. */

static struct fetch *queue_ring = 0;	/**< Ring of queued fetches */

#define fetch_ref_fetcher(F) F->refcount++

static void fetch_unref_fetcher(scheme_fetcher *fetcher);

static void fetch_dispatch_jobs(void);

static bool fetch_choose_and_dispatch(void);

static bool fetch_dispatch_job(struct fetch *fetch);

/* Static lwc_strings */

static lwc_string *fetch_http_lwc;

static lwc_string *fetch_https_lwc;

/**

 * Initialise the fetcher.

 */

void fetch_init(void)

{

	fetch_curl_register();

	fetch_data_register();

	fetch_file_register();

	fetch_resource_register();

	fetch_about_register();

	fetch_active = false;

	if (lwc_intern_string("http", SLEN("http"), &fetch_http_lwc) !=

			lwc_error_ok) {

		die("Failed to initialise the fetch module "

				"(couldn't intern \"http\").");

	}

	if (lwc_intern_string("https", SLEN("https"), &fetch_https_lwc) !=

			lwc_error_ok) {

		die("Failed to initialise the fetch module "

				"(couldn't intern \"https\").");

	}

}

/**

 * Clean up for quit.

 *

 * Must be called before exiting.

 */

void fetch_quit(void)

{

	while (fetchers != NULL) {

		if (fetchers->refcount != 1) {

			LOG(("Fetcher for scheme %s still active?!",

					lwc_string_data(fetchers->scheme_name)));

			/* We shouldn't do this, but... */

			fetchers->refcount = 1;

		}

		fetch_unref_fetcher(fetchers);

	}

	lwc_string_unref(fetch_http_lwc);

	lwc_string_unref(fetch_https_lwc);

}

bool fetch_add_fetcher(lwc_string *scheme,

		  fetcher_initialise initialiser,

		  fetcher_can_fetch can_fetch,

		  fetcher_setup_fetch setup_fetch,

		  fetcher_start_fetch start_fetch,

		  fetcher_abort_fetch abort_fetch,

		  fetcher_free_fetch free_fetch,

		  fetcher_poll_fetcher poll_fetcher,

		  fetcher_finalise finaliser)

{

	scheme_fetcher *new_fetcher;

	if (!initialiser(scheme))

		return false;

	new_fetcher = malloc(sizeof(scheme_fetcher));

	if (new_fetcher == NULL) {

		finaliser(scheme);

		return false;

	}

	new_fetcher->scheme_name = scheme;

	new_fetcher->refcount = 0;

	new_fetcher->can_fetch = can_fetch;

	new_fetcher->setup_fetch = setup_fetch;

	new_fetcher->start_fetch = start_fetch;

	new_fetcher->abort_fetch = abort_fetch;

	new_fetcher->free_fetch = free_fetch;

	new_fetcher->poll_fetcher = poll_fetcher;

	new_fetcher->finaliser = finaliser;

	new_fetcher->next_fetcher = fetchers;

	fetchers = new_fetcher;

	fetch_ref_fetcher(new_fetcher);

	return true;

}

void fetch_unref_fetcher(scheme_fetcher *fetcher)

{

	if (--fetcher->refcount == 0) {

		fetcher->finaliser(fetcher->scheme_name);

		lwc_string_unref(fetcher->scheme_name);

		if (fetcher == fetchers) {

			fetchers = fetcher->next_fetcher;

			if (fetchers)

				fetchers->prev_fetcher = NULL;

		} else {

			fetcher->prev_fetcher->next_fetcher =

					fetcher->next_fetcher;

			if (fetcher->next_fetcher != NULL)

				fetcher->next_fetcher->prev_fetcher =

						fetcher->prev_fetcher;

		}

		free(fetcher);

	}

}

/**

 * Start fetching data for the given URL.

 *

 * The function returns immediately. The fetch may be queued for later

 * processing.

 *

 * A pointer to an opaque struct fetch is returned, which can be passed to

 * fetch_abort() to abort the fetch at any time. Returns 0 if memory is

 * exhausted (or some other fatal error occurred).

 *

 * The caller must supply a callback function which is called when anything

 * interesting happens. The callback function is first called with msg

 * FETCH_HEADER, with the header in data, then one or more times

 * with FETCH_DATA with some data for the url, and finally with

 * FETCH_FINISHED. Alternatively, FETCH_ERROR indicates an error occurred:

 * data contains an error message. FETCH_REDIRECT may replace the FETCH_HEADER,

 * FETCH_DATA, FETCH_FINISHED sequence if the server sends a replacement URL.

 *

 */

struct fetch * fetch_start(nsurl *url, nsurl *referer,

			   fetch_callback callback,

			   void *p, bool only_2xx, const char *post_urlenc,

			   const struct fetch_multipart_data *post_multipart,

			   bool verifiable, bool downgrade_tls,

			   const char *headers[])

{

	struct fetch *fetch;

	scheme_fetcher *fetcher = fetchers;

	lwc_string *scheme;

	bool match;

	fetch = malloc(sizeof (*fetch));

	if (fetch == NULL)

		return NULL;

	/* The URL we're fetching must have a scheme */

	scheme = nsurl_get_component(url, NSURL_SCHEME);

	assert(scheme != NULL);

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("fetch %p, url '%s'", fetch, nsurl_access(url)));

#endif

	/* construct a new fetch structure */

	fetch->callback = callback;

	fetch->url = nsurl_ref(url);

	fetch->verifiable = verifiable;

	fetch->p = p;

	fetch->http_code = 0;

	fetch->r_prev = NULL;

	fetch->r_next = NULL;

	fetch->referer = NULL;

	fetch->send_referer = false;

	fetch->fetcher_handle = NULL;

	fetch->ops = NULL;

	fetch->fetch_is_active = false;

	fetch->host = nsurl_get_component(url, NSURL_HOST);

	if (referer != NULL) {

		lwc_string *ref_scheme;

		fetch->referer = nsurl_ref(referer);

		ref_scheme = nsurl_get_component(referer, NSURL_SCHEME);

		/* Not a problem if referer has no scheme */

		/* Determine whether to send the Referer header */

		if (nsoption_bool(send_referer) && ref_scheme != NULL) {

			/* User permits us to send the header

			 * Only send it if:

			 *    1) The fetch and referer schemes match

			 * or 2) The fetch is https and the referer is http

			 *

			 * This ensures that referer information is only sent

			 * across schemes in the special case of an https

			 * request from a page served over http. The inverse

			 * (https -> http) should not send the referer (15.1.3)

			 */

			bool match1;

			bool match2;

			if (lwc_string_isequal(scheme, ref_scheme, &match) != lwc_error_ok) {

				match = false;

			}

			if (lwc_string_isequal(scheme, fetch_https_lwc, &match1) != lwc_error_ok) {

				match1 = false;

			}

			if (lwc_string_isequal(ref_scheme, fetch_http_lwc, &match2) != lwc_error_ok) {

				match2= false;

			}

			if (match == true || (match1 == true && match2 == true))

				fetch->send_referer = true;

		}

		if (ref_scheme != NULL)

			lwc_string_unref(ref_scheme);

	}

	/* Pick the scheme ops */

	while (fetcher) {

		if ((lwc_string_isequal(fetcher->scheme_name, scheme,

				&match) == lwc_error_ok) && (match == true)) {

			fetch->ops = fetcher;

			break;

		}

		fetcher = fetcher->next_fetcher;

	}

	if (fetch->ops == NULL)

		goto failed;

	/* Got a scheme fetcher, try and set up the fetch */

	fetch->fetcher_handle = fetch->ops->setup_fetch(fetch, url,

					only_2xx, downgrade_tls,

					post_urlenc, post_multipart,

					headers);

	if (fetch->fetcher_handle == NULL)

		goto failed;

	/* Rah, got it, so ref the fetcher. */

	fetch_ref_fetcher(fetch->ops);

	/* these aren't needed past here */

	lwc_string_unref(scheme);

	/* Dump us in the queue and ask the queue to run. */

	RING_INSERT(queue_ring, fetch);

	fetch_dispatch_jobs();

	return fetch;

failed:

	lwc_string_unref(scheme);

	if (fetch->host != NULL)

		lwc_string_unref(fetch->host);

	if (fetch->url != NULL)

		nsurl_unref(fetch->url);

	if (fetch->referer != NULL)

		nsurl_unref(fetch->referer);

	free(fetch);

	return NULL;

}

/**

 * Dispatch as many jobs as we have room to dispatch.

 */

void fetch_dispatch_jobs(void)

{

	int all_active, all_queued;

#ifdef DEBUG_FETCH_VERBOSE

	struct fetch *q;

	struct fetch *f;

#endif

	if (!queue_ring)

		return; /* Nothing to do, the queue is empty */

	RING_GETSIZE(struct fetch, queue_ring, all_queued);

	RING_GETSIZE(struct fetch, fetch_ring, all_active);

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("queue_ring %i, fetch_ring %i", all_queued, all_active));

	q = queue_ring;

	if (q) {

		do {

			LOG(("queue_ring: %s", q->url));

			q = q->r_next;

		} while (q != queue_ring);

	}

	f = fetch_ring;

	if (f) {

		do {

			LOG(("fetch_ring: %s", f->url));

			f = f->r_next;

		} while (f != fetch_ring);

	}

#endif

	while ( all_queued && all_active < nsoption_int(max_fetchers) ) {

		/*LOG(("%d queued, %d fetching", all_queued, all_active));*/

		if (fetch_choose_and_dispatch()) {

			all_queued--;

			all_active++;

		} else {

			/* Either a dispatch failed or we ran out. Just stop */

			break;

		}

	}

	fetch_active = (all_active > 0);

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("Fetch ring is now %d elements.", all_active));

	LOG(("Queue ring is now %d elements.", all_queued));

#endif

}

/**

 * Choose and dispatch a single job. Return false if we failed to dispatch

 * anything.

 *

 * We don't check the overall dispatch size here because we're not called unless

 * there is room in the fetch queue for us.

 */

bool fetch_choose_and_dispatch(void)

{

	bool same_host;

	struct fetch *queueitem;

	queueitem = queue_ring;

	do {

		/* We can dispatch the selected item if there is room in the

		 * fetch ring

		 */

		int countbyhost;

		RING_COUNTBYLWCHOST(struct fetch, fetch_ring, countbyhost,

				queueitem->host);

		if (countbyhost < nsoption_int(max_fetchers_per_host)) {

			/* We can dispatch this item in theory */

			return fetch_dispatch_job(queueitem);

		}

		/* skip over other items with the same host */

		same_host = true;

		while (same_host == true && queueitem->r_next != queue_ring) {

			if (lwc_string_isequal(queueitem->host,

					queueitem->r_next->host, &same_host) ==

					lwc_error_ok && same_host == true) {

				queueitem = queueitem->r_next;

			}

		}

		queueitem = queueitem->r_next;

	} while (queueitem != queue_ring);

	return false;

}

/**

 * Dispatch a single job

 */

bool fetch_dispatch_job(struct fetch *fetch)

{

	RING_REMOVE(queue_ring, fetch);

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("Attempting to start fetch %p, fetcher %p, url %s", fetch,

			fetch->fetcher_handle, nsurl_access(fetch->url)));

#endif

	if (!fetch->ops->start_fetch(fetch->fetcher_handle)) {

		RING_INSERT(queue_ring, fetch); /* Put it back on the end of the queue */

		return false;

	} else {

		RING_INSERT(fetch_ring, fetch);

		fetch->fetch_is_active = true;

		return true;

	}

}

/**

 * Abort a fetch.

 */

void fetch_abort(struct fetch *f)

{

	assert(f);

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("fetch %p, fetcher %p, url '%s'", f, f->fetcher_handle,

			nsurl_access(f->url)));

#endif

	f->ops->abort_fetch(f->fetcher_handle);

}

/**

 * Free a fetch structure and associated resources.

 */

void fetch_free(struct fetch *f)

{

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("Freeing fetch %p, fetcher %p", f, f->fetcher_handle));

#endif

	f->ops->free_fetch(f->fetcher_handle);

	fetch_unref_fetcher(f->ops);

	nsurl_unref(f->url);

	if (f->referer != NULL)

		nsurl_unref(f->referer);

	if (f->host != NULL)

		lwc_string_unref(f->host);

        free(f);

}

/**

 * Do some work on current fetches.

 *

 * Must be called regularly to make progress on fetches.

 */

void fetch_poll(void)

{

	scheme_fetcher *fetcher = fetchers;

	scheme_fetcher *next_fetcher;

	fetch_dispatch_jobs();

	if (!fetch_active)

		return; /* No point polling, there's no fetch active. */

	while (fetcher != NULL) {

		next_fetcher = fetcher->next_fetcher;

		if (fetcher->poll_fetcher != NULL) {

			/* LOG(("Polling fetcher for %s",

			   lwc_string_data(fetcher->scheme_name))); */

			fetcher->poll_fetcher(fetcher->scheme_name);

		}

		fetcher = next_fetcher;

	}

}

/**

 * Check if a URL's scheme can be fetched.

 *

 * \param  url  URL to check

 * \return  true if the scheme is supported

 */

bool fetch_can_fetch(const nsurl *url)

{

	scheme_fetcher *fetcher = fetchers;

	bool match;

	lwc_string *scheme = nsurl_get_component(url, NSURL_SCHEME);

	while (fetcher != NULL) {

		if (lwc_string_isequal(fetcher->scheme_name, scheme, &match) == lwc_error_ok && match == true) {

			break;

		}

		fetcher = fetcher->next_fetcher;

	}

	lwc_string_unref(scheme);

	return fetcher == NULL ? false : fetcher->can_fetch(url);

}

/**

 * Change the callback function for a fetch.

 */

void fetch_change_callback(struct fetch *fetch,

			   fetch_callback callback,

			   void *p)

{

	assert(fetch);

	fetch->callback = callback;

	fetch->p = p;

}

/**

 * Get the HTTP response code.

 */

long fetch_http_code(struct fetch *fetch)

{

	return fetch->http_code;

}

/**

 * Determine if a fetch was verifiable

 *

 * \param fetch  Fetch to consider

 * \return Verifiable status of fetch

 */

bool fetch_get_verifiable(struct fetch *fetch)

{

	assert(fetch);

	return fetch->verifiable;

}

/**

 * Clone a linked list of fetch_multipart_data.

 *

 * \param list  List to clone

 * \return Pointer to head of cloned list, or NULL on failure

 */

struct fetch_multipart_data *fetch_multipart_data_clone(

		const struct fetch_multipart_data *list)

{

	struct fetch_multipart_data *clone, *last = NULL;

	struct fetch_multipart_data *result = NULL;

	for (; list != NULL; list = list->next) {

		clone = malloc(sizeof(struct fetch_multipart_data));

		if (clone == NULL) {

			if (result != NULL)

				fetch_multipart_data_destroy(result);

			return NULL;

		}

		clone->file = list->file;

		clone->name = strdup(list->name);

		if (clone->name == NULL) {

			free(clone);

			if (result != NULL)

				fetch_multipart_data_destroy(result);

			return NULL;

		}

		clone->value = strdup(list->value);

		if (clone->value == NULL) {

			free(clone->name);

			free(clone);

			if (result != NULL)

				fetch_multipart_data_destroy(result);

			return NULL;

		}

		clone->next = NULL;

		if (result == NULL)

			result = clone;

		else

			last->next = clone;

		last = clone;

	}

	return result;

}

/**

 * Free a linked list of fetch_multipart_data.

 *

 * \param list Pointer to head of list to free

 */

void fetch_multipart_data_destroy(struct fetch_multipart_data *list)

{

	struct fetch_multipart_data *next;

	for (; list != NULL; list = next) {

		next = list->next;

		free(list->name);

		free(list->value);

		free(list);

	}

}

void

fetch_send_callback(const fetch_msg *msg, struct fetch *fetch)

{

	__menuet__debug_out("Inside fetch_send_callback\n");

	fetch->callback(msg, fetch->p);

	__menuet__debug_out("After fetch->callback \n");

}

void fetch_remove_from_queues(struct fetch *fetch)

{

	int all_active, all_queued;

	/* Go ahead and free the fetch properly now */

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("Fetch %p, fetcher %p can be freed", fetch, fetch->fetcher_handle));

#endif

	if (fetch->fetch_is_active) {

		RING_REMOVE(fetch_ring, fetch);

	} else {

		RING_REMOVE(queue_ring, fetch);

	}

	RING_GETSIZE(struct fetch, fetch_ring, all_active);

	RING_GETSIZE(struct fetch, queue_ring, all_queued);

	fetch_active = (all_active > 0);

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("Fetch ring is now %d elements.", all_active));

	LOG(("Queue ring is now %d elements.", all_queued));

#endif

}

void

fetch_set_http_code(struct fetch *fetch, long http_code)

{

#ifdef DEBUG_FETCH_VERBOSE

	LOG(("Setting HTTP code to %ld", http_code));

#endif

	fetch->http_code = http_code;

}

const char *fetch_get_referer_to_send(struct fetch *fetch)

{

	if (fetch->send_referer)

		return nsurl_access(fetch->referer);

	return NULL;

}

void

fetch_set_cookie(struct fetch *fetch, const char *data)

{

	assert(fetch && data);

	/* If the fetch is unverifiable err on the side of caution and

	 * do not set the cookie */

	if (fetch->verifiable) {

		/* If the transaction's verifiable, we don't require

		 * that the request uri and the parent domain match,

		 * so don't pass in any referer/parent in this case. */

		urldb_set_cookie(data, fetch->url, NULL);

	} else if (fetch->referer != NULL) {

		/* Permit the cookie to be set if the fetch is unverifiable

		 * and the fetch URI domain matches the referer. */

		/** \todo Long-term, this needs to be replaced with a

		 * comparison against the origin fetch URI. In the case

		 * where a nested object requests a fetch, the origin URI

		 * is the nested object's parent URI, whereas the referer

		 * for the fetch will be the nested object's URI. */

		urldb_set_cookie(data, fetch->url, fetch->referer);

	}

}