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• This comparison shows the changes necessary to convert path

  → /contrib/network/netsurf/netsurf/content/llcache.c @ 4363

  → /contrib/network/netsurf/netsurf/content/llcache.c @ 4364

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Regard whitespace Rev 4363 → Rev 4364

/contrib/network/netsurf/netsurf/content/llcache.c
0,0 → 1,2590
/*
* Copyright 2009 John-Mark Bell <jmb@netsurf-browser.org>
*
* 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 <http://www.gnu.org/licenses/>.
*/
/** \file
* Low-level resource cache (implementation)
*/
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <curl/curl.h>
#include "content/fetch.h"
#include "content/llcache.h"
#include "content/urldb.h"
#include "utils/log.h"
#include "utils/messages.h"
#include "utils/nsurl.h"
#include "utils/utils.h"
/** Define to enable tracing of llcache operations. */
#undef LLCACHE_TRACE
/** State of a low-level cache object fetch */
typedef enum {
LLCACHE_FETCH_INIT, /**< Initial state, before fetch */
LLCACHE_FETCH_HEADERS, /**< Fetching headers */
LLCACHE_FETCH_DATA, /**< Fetching object data */
LLCACHE_FETCH_COMPLETE /**< Fetch completed */
} llcache_fetch_state;
/** Type of low-level cache object */
typedef struct llcache_object llcache_object;
/** Handle to low-level cache object */
struct llcache_handle {
llcache_object *object; /**< Pointer to associated object */
llcache_handle_callback cb; /**< Client callback */
void *pw; /**< Client data */
llcache_fetch_state state; /**< Last known state of object fetch */
size_t bytes; /**< Last reported byte count */
};
/** Low-level cache object user record */
typedef struct llcache_object_user {
llcache_handle *handle; /**< Handle data for client */
bool iterator_target; /**< This is the an iterator target */
bool queued_for_delete; /**< This user is queued for deletion */
struct llcache_object_user *prev; /**< Previous in list */
struct llcache_object_user *next; /**< Next in list */
} llcache_object_user;
/** Low-level cache object fetch context */
typedef struct {
uint32_t flags; /**< Fetch flags */
nsurl *referer; /**< Referring URL, or NULL if none */
llcache_post_data *post; /**< POST data, or NULL for GET */
struct fetch *fetch; /**< Fetch handle for this object */
llcache_fetch_state state; /**< Current state of object fetch */
uint32_t redirect_count; /**< Count of redirects followed */
bool tried_with_auth; /**< Whether we've tried with auth */
bool tried_with_tls_downgrade; /**< Whether we've tried TLS <= 1.0 */
bool outstanding_query; /**< Waiting for a query response */
} llcache_fetch_ctx;
typedef enum {
LLCACHE_VALIDATE_FRESH, /**< Only revalidate if not fresh */
LLCACHE_VALIDATE_ALWAYS, /**< Always revalidate */
LLCACHE_VALIDATE_ONCE /**< Revalidate once only */
} llcache_validate;
/** Cache control data */
typedef struct {
time_t req_time; /**< Time of request */
time_t res_time; /**< Time of response */
time_t date; /**< Date: response header */
time_t expires; /**< Expires: response header */
#define INVALID_AGE -1
int age; /**< Age: response header */
int max_age; /**< Max-Age Cache-control parameter */
llcache_validate no_cache; /**< No-Cache Cache-control parameter */
char *etag; /**< Etag: response header */
time_t last_modified; /**< Last-Modified: response header */
} llcache_cache_control;
/** Representation of a fetch header */
typedef struct {
char *name; /**< Header name */
char *value; /**< Header value */
} llcache_header;
/** Low-level cache object */
/** \todo Consider whether a list is a sane container */
struct llcache_object {
llcache_object *prev; /**< Previous in list */
llcache_object *next; /**< Next in list */
nsurl *url; /**< Post-redirect URL for object */
bool has_query; /**< URL has a query segment */
/** \todo We need a generic dynamic buffer object */
uint8_t *source_data; /**< Source data for object */
size_t source_len; /**< Byte length of source data */
size_t source_alloc; /**< Allocated size of source buffer */
llcache_object_user *users; /**< List of users */
llcache_fetch_ctx fetch; /**< Fetch context for object */
llcache_cache_control cache; /**< Cache control data for object */
llcache_object *candidate; /**< Object to use, if fetch determines
* that it is still fresh */
uint32_t candidate_count; /**< Count of objects this is a
* candidate for */
llcache_header *headers; /**< Fetch headers */
size_t num_headers; /**< Number of fetch headers */
};
struct llcache_s {
/** Handler for fetch-related queries */
llcache_query_callback query_cb;
/** Data for fetch-related query handler */
void *query_cb_pw;
/** Head of the low-level cached object list */
llcache_object *cached_objects;
/** Head of the low-level uncached object list */
llcache_object *uncached_objects;
uint32_t limit;
};
/** low level cache state */
static struct llcache_s *llcache = NULL;
/* Static lwc_strings */
static lwc_string *llcache_file_lwc;
static lwc_string *llcache_about_lwc;
static lwc_string *llcache_resource_lwc;
/* forward referenced callback function */
static void llcache_fetch_callback(const fetch_msg *msg, void *p);
/******************************************************************************
* Low-level cache internals *
******************************************************************************/
/**
* Create a new object user
*
* \param cb Callback routine
* \param pw Private data for callback
* \param user Pointer to location to receive result
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_object_user_new(llcache_handle_callback cb, void *pw,
llcache_object_user **user)
{
llcache_handle *h;
llcache_object_user *u;
h = calloc(1, sizeof(llcache_handle));
if (h == NULL)
return NSERROR_NOMEM;
u = calloc(1, sizeof(llcache_object_user));
if (u == NULL) {
free(h);
return NSERROR_NOMEM;
}
h->cb = cb;
h->pw = pw;
u->handle = h;
#ifdef LLCACHE_TRACE
LOG(("Created user %p (%p, %p, %p)", u, h, (void *) cb, pw));
#endif
*user = u;
return NSERROR_OK;
}
/**
* Destroy an object user
*
* \param user User to destroy
* \return NSERROR_OK on success, appropriate error otherwise
*
* \pre User is not attached to an object
*/
static nserror llcache_object_user_destroy(llcache_object_user *user)
{
#ifdef LLCACHE_TRACE
LOG(("Destroyed user %p", user));
#endif
assert(user->next == NULL);
assert(user->prev == NULL);
if (user->handle != NULL)
free(user->handle);
free(user);
return NSERROR_OK;
}
/**
* Remove a user from a low-level cache object
*
* \param object Object to remove user from
* \param user User to remove
* \return NSERROR_OK.
*/
static nserror llcache_object_remove_user(llcache_object *object,
llcache_object_user *user)
{
assert(user != NULL);
assert(object != NULL);
assert(object->users != NULL);
assert(user->handle == NULL || user->handle->object == object);
assert((user->prev != NULL) || (object->users == user));
if (user == object->users)
object->users = user->next;
else
user->prev->next = user->next;
if (user->next != NULL)
user->next->prev = user->prev;
user->next = user->prev = NULL;
#ifdef LLCACHE_TRACE
LOG(("Removing user %p from %p", user, object));
#endif
return NSERROR_OK;
}
/**
* Iterate the users of an object, calling their callbacks.
*
* \param object The object to iterate
* \param event The event to pass to the callback.
* \return NSERROR_OK on success, appropriate error otherwise.
*/
static nserror llcache_send_event_to_users(llcache_object *object,
llcache_event *event)
{
nserror error = NSERROR_OK;
llcache_object_user *user, *next_user;
user = object->users;
while (user != NULL) {
user->iterator_target = true;
error = user->handle->cb(user->handle, event,
user->handle->pw);
next_user = user->next;
user->iterator_target = false;
if (user->queued_for_delete) {
llcache_object_remove_user(object, user);
llcache_object_user_destroy(user);
}
if (error != NSERROR_OK)
break;
user = next_user;
}
return error;
}
/**
* Create a new low-level cache object
*
* \param url URL of object to create
* \param result Pointer to location to receive result
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_object_new(nsurl *url, llcache_object **result)
{
llcache_object *obj = calloc(1, sizeof(llcache_object));
if (obj == NULL)
return NSERROR_NOMEM;
#ifdef LLCACHE_TRACE
LOG(("Created object %p (%s)", obj, nsurl_access(url)));
#endif
obj->url = nsurl_ref(url);
*result = obj;
return NSERROR_OK;
}
/**
* Clone a POST data object
*
* \param orig Object to clone
* \param clone Pointer to location to receive clone
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_post_data_clone(const llcache_post_data *orig,
llcache_post_data **clone)
{
llcache_post_data *post_clone;
post_clone = calloc(1, sizeof(llcache_post_data));
if (post_clone == NULL)
return NSERROR_NOMEM;
post_clone->type = orig->type;
/* Deep-copy the type-specific data */
if (orig->type == LLCACHE_POST_URL_ENCODED) {
post_clone->data.urlenc = strdup(orig->data.urlenc);
if (post_clone->data.urlenc == NULL) {
free(post_clone);
return NSERROR_NOMEM;
}
} else {
post_clone->data.multipart = fetch_multipart_data_clone(
orig->data.multipart);
if (post_clone->data.multipart == NULL) {
free(post_clone);
return NSERROR_NOMEM;
}
}
*clone = post_clone;
return NSERROR_OK;
}
/**
* Split a fetch header into name and value
*
* \param data Header string
* \param len Byte length of header
* \param name Pointer to location to receive header name
* \param value Pointer to location to receive header value
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_fetch_split_header(const uint8_t *data, size_t len,
char **name, char **value)
{
char *n, *v;
const uint8_t *colon;
/* Find colon */
colon = (const uint8_t *) strchr((const char *) data, ':');
if (colon == NULL) {
/* Failed, assume a key with no value */
n = strdup((const char *) data);
if (n == NULL)
return NSERROR_NOMEM;
v = strdup("");
if (v == NULL) {
free(n);
return NSERROR_NOMEM;
}
} else {
/* Split header into name & value */
/* Strip leading whitespace from name */
while (data[0] == ' ' || data[0] == '\t' ||
data[0] == '\r' || data[0] == '\n') {
data++;
}
/* Strip trailing whitespace from name */
while (colon > data && (colon[-1] == ' ' ||
colon[-1] == '\t' || colon[-1] == '\r' ||
colon[-1] == '\n'))
colon--;
n = strndup((const char *) data, colon - data);
if (n == NULL)
return NSERROR_NOMEM;
/* Find colon again */
while (*colon != ':') {
colon++;
}
/* Skip over colon and any subsequent whitespace */
do {
colon++;
} while (*colon == ' ' || *colon == '\t' ||
*colon == '\r' || *colon == '\n');
/* Strip trailing whitespace from value */
while (len > 0 && (data[len - 1] == ' ' ||
data[len - 1] == '\t' ||
data[len - 1] == '\r' ||
data[len - 1] == '\n')) {
len--;
}
v = strndup((const char *) colon, len - (colon - data));
if (v == NULL) {
free(n);
return NSERROR_NOMEM;
}
}
*name = n;
*value = v;
return NSERROR_OK;
}
/**
* Parse a fetch header
*
* \param object Object to parse header for
* \param data Header string
* \param len Byte length of header
* \param name Pointer to location to receive header name
* \param value Pointer to location to receive header value
* \return NSERROR_OK on success, appropriate error otherwise
*
* \note This function also has the side-effect of updating
* the cache control data for the object if an interesting
* header is encountered
*/
static nserror llcache_fetch_parse_header(llcache_object *object,
const uint8_t *data, size_t len, char **name, char **value)
{
nserror error;
/* Set fetch response time if not already set */
if (object->cache.res_time == 0)
object->cache.res_time = time(NULL);
/* Decompose header into name-value pair */
error = llcache_fetch_split_header(data, len, name, value);
if (error != NSERROR_OK)
return error;
/* Parse cache headers to populate cache control data */
#define SKIP_ST(p) while (*p != '\0' && (*p == ' ' || *p == '\t')) p++
if (5 < len && strcasecmp(*name, "Date") == 0) {
/* extract Date header */
object->cache.date = curl_getdate(*value, NULL);
} else if (4 < len && strcasecmp(*name, "Age") == 0) {
/* extract Age header */
if ('0' <= **value && **value <= '9')
object->cache.age = atoi(*value);
} else if (8 < len && strcasecmp(*name, "Expires") == 0) {
/* extract Expires header */
object->cache.expires = curl_getdate(*value, NULL);
} else if (14 < len && strcasecmp(*name, "Cache-Control") == 0) {
/* extract and parse Cache-Control header */
const char *start = *value;
const char *comma = *value;
while (*comma != '\0') {
while (*comma != '\0' && *comma != ',')
comma++;
if (8 < comma - start && (strncasecmp(start,
"no-cache", 8) == 0 ||
strncasecmp(start, "no-store", 8) == 0))
/* When we get a disk cache we should
* distinguish between these two */
object->cache.no_cache = LLCACHE_VALIDATE_ALWAYS;
else if (7 < comma - start &&
strncasecmp(start, "max-age", 7) == 0) {
/* Find '=' */
while (start < comma && *start != '=')
start++;
/* Skip over it */
start++;
/* Skip whitespace */
SKIP_ST(start);
if (start < comma)
object->cache.max_age = atoi(start);
}
if (*comma != '\0') {
/* Skip past comma */
comma++;
/* Skip whitespace */
SKIP_ST(comma);
}
/* Set start for next token */
start = comma;
}
} else if (5 < len && strcasecmp(*name, "ETag") == 0) {
/* extract ETag header */
free(object->cache.etag);
object->cache.etag = strdup(*value);
if (object->cache.etag == NULL)
return NSERROR_NOMEM;
} else if (14 < len && strcasecmp(*name, "Last-Modified") == 0) {
/* extract Last-Modified header */
object->cache.last_modified = curl_getdate(*value, NULL);
}
#undef SKIP_ST
return NSERROR_OK;
}
/* Destroy headers */
static inline void llcache_destroy_headers(llcache_object *object)
{
while (object->num_headers > 0) {
object->num_headers--;
free(object->headers[object->num_headers].name);
free(object->headers[object->num_headers].value);
}
free(object->headers);
object->headers = NULL;
}
/* Invalidate cache control data */
static inline void llcache_invalidate_cache_control_data(llcache_object *object)
{
free(object->cache.etag);
memset(&(object->cache), 0, sizeof(llcache_cache_control));
object->cache.age = INVALID_AGE;
object->cache.max_age = INVALID_AGE;
}
/**
* Process a fetch header
*
* \param object Object being fetched
* \param data Header string
* \param len Byte length of header
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_fetch_process_header(llcache_object *object,
const uint8_t *data, size_t len)
{
nserror error;
char *name, *value;
llcache_header *temp;
/* The headers for multiple HTTP responses may be delivered to us if
* the fetch layer receives a 401 response for which it has
* authentication credentials. This will result in a silent re-request
* after which we'll receive the actual response headers for the
* object we want to fetch (assuming that the credentials were correct
* of course)
*
* Therefore, if the header is an HTTP response start marker, then we
* must discard any headers we've read so far, reset the cache data
* that we might have computed, and start again.
*/
/** \todo Properly parse the response line */
if (strncmp((const char *) data, "HTTP/", SLEN("HTTP/")) == 0) {
time_t req_time = object->cache.req_time;
llcache_invalidate_cache_control_data(object);
/* Restore request time, so we compute object's age correctly */
object->cache.req_time = req_time;
llcache_destroy_headers(object);
}
error = llcache_fetch_parse_header(object, data, len, &name, &value);
if (error != NSERROR_OK)
return error;
/* Append header data to the object's headers array */
temp = realloc(object->headers, (object->num_headers + 1) *
sizeof(llcache_header));
if (temp == NULL) {
free(name);
free(value);
return NSERROR_NOMEM;
}
object->headers = temp;
object->headers[object->num_headers].name = name;
object->headers[object->num_headers].value = value;
object->num_headers++;
return NSERROR_OK;
}
/**
* (Re)fetch an object
*
* \param object Object to refetch
* \return NSERROR_OK on success, appropriate error otherwise
*
* \pre The fetch parameters in object->fetch must be populated
*/
static nserror llcache_object_refetch(llcache_object *object)
{
const char *urlenc = NULL;
struct fetch_multipart_data *multipart = NULL;
char **headers = NULL;
int header_idx = 0;
if (object->fetch.post != NULL) {
if (object->fetch.post->type == LLCACHE_POST_URL_ENCODED)
urlenc = object->fetch.post->data.urlenc;
else
multipart = object->fetch.post->data.multipart;
}
/* Generate cache-control headers */
headers = malloc(3 * sizeof(char *));
if (headers == NULL)
return NSERROR_NOMEM;
if (object->cache.etag != NULL) {
const size_t len = SLEN("If-None-Match: ") +
strlen(object->cache.etag) + 1;
headers[header_idx] = malloc(len);
if (headers[header_idx] == NULL) {
free(headers);
return NSERROR_NOMEM;
}
snprintf(headers[header_idx], len, "If-None-Match: %s",
object->cache.etag);
header_idx++;
}
if (object->cache.date != 0) {
/* Maximum length of an RFC 1123 date is 29 bytes */
const size_t len = SLEN("If-Modified-Since: ") + 29 + 1;
headers[header_idx] = malloc(len);
if (headers[header_idx] == NULL) {
while (--header_idx >= 0)
free(headers[header_idx]);
free(headers);
return NSERROR_NOMEM;
}
snprintf(headers[header_idx], len, "If-Modified-Since: %s",
rfc1123_date(object->cache.date));
header_idx++;
}
headers[header_idx] = NULL;
/* Reset cache control data */
llcache_invalidate_cache_control_data(object);
object->cache.req_time = time(NULL);
/* Reset fetch state */
object->fetch.state = LLCACHE_FETCH_INIT;
#ifdef LLCACHE_TRACE
LOG(("Refetching %p", object));
#endif
/* Kick off fetch */
object->fetch.fetch = fetch_start(object->url, object->fetch.referer,
llcache_fetch_callback, object,
object->fetch.flags & LLCACHE_RETRIEVE_NO_ERROR_PAGES,
urlenc, multipart,
object->fetch.flags & LLCACHE_RETRIEVE_VERIFIABLE,
object->fetch.tried_with_tls_downgrade,
(const char **) headers);
/* Clean up cache-control headers */
while (--header_idx >= 0)
free(headers[header_idx]);
free(headers);
/* Did we succeed in creating a fetch? */
if (object->fetch.fetch == NULL)
return NSERROR_NOMEM;
return NSERROR_OK;
}
/**
* Kick-off a fetch for an object
*
* \param object Object to fetch
* \param flags Fetch flags
* \param referer Referring URL, or NULL for none
* \param post POST data, or NULL for GET
* \param redirect_count Number of redirects followed so far
* \return NSERROR_OK on success, appropriate error otherwise
*
* \pre object::url must contain the URL to fetch
* \pre If there is a freshness validation candidate,
* object::candidate and object::cache must be filled in
* \pre There must not be a fetch in progress for \a object
*/
static nserror llcache_object_fetch(llcache_object *object, uint32_t flags,
nsurl *referer, const llcache_post_data *post,
uint32_t redirect_count)
{
nserror error;
nsurl *referer_clone = NULL;
llcache_post_data *post_clone = NULL;
#ifdef LLCACHE_TRACE
LOG(("Starting fetch for %p", object));
#endif
if (post != NULL) {
error = llcache_post_data_clone(post, &post_clone);
if (error != NSERROR_OK)
return error;
}
if (referer != NULL)
referer_clone = nsurl_ref(referer);
object->fetch.flags = flags;
object->fetch.referer = referer_clone;
object->fetch.post = post_clone;
object->fetch.redirect_count = redirect_count;
return llcache_object_refetch(object);
}
/**
* Destroy a low-level cache object
*
* \param object Object to destroy
* \return NSERROR_OK on success, appropriate error otherwise
*
* \pre Object is detached from cache list
* \pre Object has no users
* \pre Object is not a candidate (i.e. object::candidate_count == 0)
*/
static nserror llcache_object_destroy(llcache_object *object)
{
size_t i;
#ifdef LLCACHE_TRACE
LOG(("Destroying object %p", object));
#endif
nsurl_unref(object->url);
free(object->source_data);
if (object->fetch.fetch != NULL) {
fetch_abort(object->fetch.fetch);
object->fetch.fetch = NULL;
}
if (object->fetch.referer != NULL)
nsurl_unref(object->fetch.referer);
if (object->fetch.post != NULL) {
if (object->fetch.post->type == LLCACHE_POST_URL_ENCODED) {
free(object->fetch.post->data.urlenc);
} else {
fetch_multipart_data_destroy(
object->fetch.post->data.multipart);
}
free(object->fetch.post);
}
free(object->cache.etag);
for (i = 0; i < object->num_headers; i++) {
free(object->headers[i].name);
free(object->headers[i].value);
}
free(object->headers);
free(object);
return NSERROR_OK;
}
/**
* Add a low-level cache object to a cache list
*
* \param object Object to add
* \param list List to add to
* \return NSERROR_OK
*/
static nserror llcache_object_add_to_list(llcache_object *object,
llcache_object **list)
{
object->prev = NULL;
object->next = *list;
if (*list != NULL)
(*list)->prev = object;
*list = object;
return NSERROR_OK;
}
/**
* Determine the remaining lifetime of a cache object using the
*
* \param object Object to consider
* \return True if object is still fresh, false otherwise
*/
static int
llcache_object_rfc2616_remaining_lifetime(const llcache_cache_control *cd)
{
int current_age, freshness_lifetime;
time_t now = time(NULL);
/* Calculate staleness of cached object as per RFC 2616 13.2.3/13.2.4 */
current_age = max(0, (cd->res_time - cd->date));
current_age = max(current_age, (cd->age == INVALID_AGE) ? 0 : cd->age);
current_age += cd->res_time - cd->req_time + now - cd->res_time;
/* Determine freshness lifetime of this object */
if (cd->max_age != INVALID_AGE)
freshness_lifetime = cd->max_age;
else if (cd->expires != 0)
freshness_lifetime = cd->expires - cd->date;
else if (cd->last_modified != 0)
freshness_lifetime = (now - cd->last_modified) / 10;
else
freshness_lifetime = 0;
#ifdef LLCACHE_TRACE
LOG(("%d:%d", freshness_lifetime, current_age));
#endif
if ((cd->no_cache == LLCACHE_VALIDATE_FRESH) &&
(freshness_lifetime > current_age)) {
/* object was not forbidden from being returned from
* the cache unvalidated (i.e. the response contained
* a no-cache directive)
*
* The object current age is within the freshness lifetime.
*/
return freshness_lifetime - current_age;
}
return 0; /* object has no remaining lifetime */
}
/**
* Determine if an object is still fresh
*
* \param object Object to consider
* \return True if object is still fresh, false otherwise
*/
static bool llcache_object_is_fresh(const llcache_object *object)
{
int remaining_lifetime;
const llcache_cache_control *cd = &object->cache;
remaining_lifetime = llcache_object_rfc2616_remaining_lifetime(cd);
#ifdef LLCACHE_TRACE
LOG(("%p: (%d > 0 || %d != %d)", object,
remaining_lifetime,
object->fetch.state, LLCACHE_FETCH_COMPLETE));
#endif
/* The object is fresh if:
* - it was not forbidden from being returned from the cache
* unvalidated.
*
* - it has remaining lifetime or still being fetched.
*/
return ((cd->no_cache == LLCACHE_VALIDATE_FRESH) &&
((remaining_lifetime > 0) ||
(object->fetch.state != LLCACHE_FETCH_COMPLETE)));
}
/**
* Clone an object's cache data
*
* \param source Source object containing cache data to clone
* \param destination Destination object to clone cache data into
* \param deep Whether to deep-copy the data or not
* \return NSERROR_OK on success, appropriate error otherwise
*
* \post If \a deep is false, then any pointers in \a source will be set to NULL
*/
static nserror llcache_object_clone_cache_data(llcache_object *source,
llcache_object *destination, bool deep)
{
/* ETag must be first, as it can fail when deep cloning */
if (source->cache.etag != NULL) {
char *etag = source->cache.etag;
if (deep) {
/* Copy the etag */
etag = strdup(source->cache.etag);
if (etag == NULL)
return NSERROR_NOMEM;
} else {
/* Destination takes ownership */
source->cache.etag = NULL;
}
if (destination->cache.etag != NULL)
free(destination->cache.etag);
destination->cache.etag = etag;
}
destination->cache.req_time = source->cache.req_time;
destination->cache.res_time = source->cache.res_time;
if (source->cache.date != 0)
destination->cache.date = source->cache.date;
if (source->cache.expires != 0)
destination->cache.expires = source->cache.expires;
if (source->cache.age != INVALID_AGE)
destination->cache.age = source->cache.age;
if (source->cache.max_age != INVALID_AGE)
destination->cache.max_age = source->cache.max_age;
if (source->cache.no_cache != LLCACHE_VALIDATE_FRESH)
destination->cache.no_cache = source->cache.no_cache;
if (source->cache.last_modified != 0)
destination->cache.last_modified = source->cache.last_modified;
return NSERROR_OK;
}
/**
* Retrieve a potentially cached object
*
* \param url URL of object to retrieve
* \param flags Fetch flags
* \param referer Referring URL, or NULL if none
* \param post POST data, or NULL for a GET request
* \param redirect_count Number of redirects followed so far
* \param result Pointer to location to recieve retrieved object
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_object_retrieve_from_cache(nsurl *url, uint32_t flags,
nsurl *referer, const llcache_post_data *post,
uint32_t redirect_count, llcache_object **result)
{
nserror error;
llcache_object *obj, *newest = NULL;
#ifdef LLCACHE_TRACE
LOG(("Searching cache for %s (%x %s %p)", url, flags, referer, post));
#endif
/* Search for the most recently fetched matching object */
for (obj = llcache->cached_objects; obj != NULL; obj = obj->next) {
if ((newest == NULL ||
obj->cache.req_time > newest->cache.req_time) &&
nsurl_compare(obj->url, url,
NSURL_COMPLETE) == true) {
newest = obj;
}
}
if (newest != NULL && llcache_object_is_fresh(newest)) {
/* Found a suitable object, and it's still fresh, so use it */
obj = newest;
#ifdef LLCACHE_TRACE
LOG(("Found fresh %p", obj));
#endif
/* The client needs to catch up with the object's state.
* This will occur the next time that llcache_poll is called.
*/
} else if (newest != NULL) {
/* Found a candidate object but it needs freshness validation */
/* Create a new object */
error = llcache_object_new(url, &obj);
if (error != NSERROR_OK)
return error;
#ifdef LLCACHE_TRACE
LOG(("Found candidate %p (%p)", obj, newest));
#endif
/* Clone candidate's cache data */
error = llcache_object_clone_cache_data(newest, obj, true);
if (error != NSERROR_OK) {
llcache_object_destroy(obj);
return error;
}
/* Record candidate, so we can fall back if it is still fresh */
newest->candidate_count++;
obj->candidate = newest;
/* Attempt to kick-off fetch */
error = llcache_object_fetch(obj, flags, referer, post,
redirect_count);
if (error != NSERROR_OK) {
newest->candidate_count--;
llcache_object_destroy(obj);
return error;
}
/* Add new object to cache */
llcache_object_add_to_list(obj, &llcache->cached_objects);
} else {
/* No object found; create a new one */
/* Create new object */
error = llcache_object_new(url, &obj);
if (error != NSERROR_OK)
return error;
#ifdef LLCACHE_TRACE
LOG(("Not found %p", obj));
#endif
/* Attempt to kick-off fetch */
error = llcache_object_fetch(obj, flags, referer, post,
redirect_count);
if (error != NSERROR_OK) {
llcache_object_destroy(obj);
return error;
}
/* Add new object to cache */
llcache_object_add_to_list(obj, &llcache->cached_objects);
}
*result = obj;
return NSERROR_OK;
}
/**
* Retrieve an object from the cache, fetching it if necessary.
*
* \param url URL of object to retrieve
* \param flags Fetch flags
* \param referer Referring URL, or NULL if none
* \param post POST data, or NULL for a GET request
* \param redirect_count Number of redirects followed so far
* \param result Pointer to location to recieve retrieved object
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_object_retrieve(nsurl *url, uint32_t flags,
nsurl *referer, const llcache_post_data *post,
uint32_t redirect_count, llcache_object **result)
{
nserror error;
llcache_object *obj;
bool has_query;
nsurl *defragmented_url;
#ifdef LLCACHE_TRACE
LOG(("Retrieve %s (%x, %s, %p)", url, flags, referer, post));
#endif
/**
* Caching Rules:
*
* 1) Forced fetches are never cached
* 2) POST requests are never cached
*/
/* Look for a query segment */
has_query = nsurl_has_component(url, NSURL_QUERY);
/* Get rid of any url fragment */
if (nsurl_has_component(url, NSURL_FRAGMENT)) {
error = nsurl_defragment(url, &defragmented_url);
if (error != NSERROR_OK)
return error;
} else {
defragmented_url = nsurl_ref(url);
}
if (flags & LLCACHE_RETRIEVE_FORCE_FETCH || post != NULL) {
/* Create new object */
error = llcache_object_new(defragmented_url, &obj);
if (error != NSERROR_OK) {
nsurl_unref(defragmented_url);
return error;
}
/* Attempt to kick-off fetch */
error = llcache_object_fetch(obj, flags, referer, post,
redirect_count);
if (error != NSERROR_OK) {
llcache_object_destroy(obj);
nsurl_unref(defragmented_url);
return error;
}
/* Add new object to uncached list */
llcache_object_add_to_list(obj, &llcache->uncached_objects);
} else {
error = llcache_object_retrieve_from_cache(defragmented_url,
flags, referer, post, redirect_count, &obj);
if (error != NSERROR_OK) {
nsurl_unref(defragmented_url);
return error;
}
/* Returned object is already in the cached list */
}
obj->has_query = has_query;
#ifdef LLCACHE_TRACE
LOG(("Retrieved %p", obj));
#endif
*result = obj;
nsurl_unref(defragmented_url);
return NSERROR_OK;
}
/**
* Add a user to a low-level cache object
*
* \param object Object to add user to
* \param user User to add
* \return NSERROR_OK.
*/
static nserror llcache_object_add_user(llcache_object *object,
llcache_object_user *user)
{
assert(user->next == NULL);
assert(user->prev == NULL);
user->handle->object = object;
user->prev = NULL;
user->next = object->users;
if (object->users != NULL)
object->users->prev = user;
object->users = user;
#ifdef LLCACHE_TRACE
LOG(("Adding user %p to %p", user, object));
#endif
return NSERROR_OK;
}
/**
* Handle FETCH_REDIRECT event
*
* \param object Object being redirected
* \param target Target of redirect (may be relative)
* \param replacement Pointer to location to receive replacement object
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_fetch_redirect(llcache_object *object, const char *target,
llcache_object **replacement)
{
nserror error;
llcache_object *dest;
llcache_object_user *user, *next;
const llcache_post_data *post = object->fetch.post;
nsurl *url;
lwc_string *scheme;
lwc_string *object_scheme;
bool match;
/* Extract HTTP response code from the fetch object */
long http_code = fetch_http_code(object->fetch.fetch);
/* Abort fetch for this object */
fetch_abort(object->fetch.fetch);
object->fetch.fetch = NULL;
/* Invalidate the cache control data */
llcache_invalidate_cache_control_data(object);
/* And mark it complete */
object->fetch.state = LLCACHE_FETCH_COMPLETE;
/* Forcibly stop redirecting if we've followed too many redirects */
#define REDIRECT_LIMIT 10
if (object->fetch.redirect_count > REDIRECT_LIMIT) {
llcache_event event;
LOG(("Too many nested redirects"));
event.type = LLCACHE_EVENT_ERROR;
event.data.msg = messages_get("BadRedirect");
return llcache_send_event_to_users(object, &event);
}
#undef REDIRECT_LIMIT
/* Make target absolute */
error = nsurl_join(object->url, target, &url);
if (error != NSERROR_OK)
return error;
/* Reject attempts to redirect from unvalidated to validated schemes
* A "validated" scheme is one over which we have some guarantee that
* the source is trustworthy. */
object_scheme = nsurl_get_component(object->url, NSURL_SCHEME);
scheme = nsurl_get_component(url, NSURL_SCHEME);
/* resource: and about: are allowed to redirect anywhere */
if ((lwc_string_isequal(object_scheme, llcache_resource_lwc,
&match) == lwc_error_ok && match == false) &&
(lwc_string_isequal(object_scheme, llcache_about_lwc,
&match) == lwc_error_ok && match == false)) {
/* file, about and resource are not valid redirect targets */
if ((lwc_string_isequal(object_scheme, llcache_file_lwc,
&match) == lwc_error_ok && match == true) ||
(lwc_string_isequal(object_scheme, llcache_about_lwc,
&match) == lwc_error_ok && match == true) ||
(lwc_string_isequal(object_scheme, llcache_resource_lwc,
&match) == lwc_error_ok && match == true)) {
lwc_string_unref(object_scheme);
lwc_string_unref(scheme);
nsurl_unref(url);
return NSERROR_OK;
}
}
lwc_string_unref(scheme);
lwc_string_unref(object_scheme);
/* Bail out if we've no way of handling this URL */
if (fetch_can_fetch(url) == false) {
nsurl_unref(url);
return NSERROR_OK;
}
if (http_code == 301 || http_code == 302 || http_code == 303) {
/* 301, 302, 303 redirects are all unconditional GET requests */
post = NULL;
} else if (http_code != 307 || post != NULL) {
/** \todo 300, 305, 307 with POST */
nsurl_unref(url);
return NSERROR_OK;
}
/* Attempt to fetch target URL */
error = llcache_object_retrieve(url, object->fetch.flags,
object->fetch.referer, post,
object->fetch.redirect_count + 1, &dest);
/* No longer require url */
nsurl_unref(url);
if (error != NSERROR_OK)
return error;
/* Move user(s) to replacement object */
for (user = object->users; user != NULL; user = next) {
next = user->next;
llcache_object_remove_user(object, user);
llcache_object_add_user(dest, user);
}
/* Dest is now our object */
*replacement = dest;
return NSERROR_OK;
}
/**
* Update an object's cache state
*
* \param object Object to update cache for
* \return NSERROR_OK.
*/
static nserror llcache_object_cache_update(llcache_object *object)
{
if (object->cache.date == 0)
object->cache.date = time(NULL);
return NSERROR_OK;
}
/**
* Handle FETCH_NOTMODIFIED event
*
* \param object Object to process
* \param replacement Pointer to location to receive replacement object
* \return NSERROR_OK.
*/
static nserror llcache_fetch_notmodified(llcache_object *object,
llcache_object **replacement)
{
/* There may be no candidate if the server erroneously responded
* to an unconditional request with a 304 Not Modified response.
* In this case, we simply retain the initial object, having
* invalidated it and marked it as complete.
*/
if (object->candidate != NULL) {
llcache_object_user *user, *next;
/* Move user(s) to candidate content */
for (user = object->users; user != NULL; user = next) {
next = user->next;
llcache_object_remove_user(object, user);
llcache_object_add_user(object->candidate, user);
}
/* Candidate is no longer a candidate for us */
object->candidate->candidate_count--;
/* Clone our cache control data into the candidate */
llcache_object_clone_cache_data(object, object->candidate,
false);
/* Bring candidate's cache data up to date */
llcache_object_cache_update(object->candidate);
/* Revert no-cache to normal, if required */
if (object->candidate->cache.no_cache ==
LLCACHE_VALIDATE_ONCE) {
object->candidate->cache.no_cache =
LLCACHE_VALIDATE_FRESH;
}
/* Candidate is now our object */
*replacement = object->candidate;
object->candidate = NULL;
} else {
/* There was no candidate: retain object */
*replacement = object;
}
/* Ensure fetch has stopped */
fetch_abort(object->fetch.fetch);
object->fetch.fetch = NULL;
/* Invalidate our cache-control data */
llcache_invalidate_cache_control_data(object);
/* Mark it complete */
object->fetch.state = LLCACHE_FETCH_COMPLETE;
/* Old object will be flushed from the cache on the next poll */
return NSERROR_OK;
}
/**
* Process a chunk of fetched data
*
* \param object Object being fetched
* \param data Data to process
* \param len Byte length of data
* \return NSERROR_OK on success, appropriate error otherwise.
*/
static nserror llcache_fetch_process_data(llcache_object *object, const uint8_t *data,
size_t len)
{
/* Resize source buffer if it's too small */
if (object->source_len + len >= object->source_alloc) {
const size_t new_len = object->source_len + len + 64 * 1024;
uint8_t *temp = realloc(object->source_data, new_len);
if (temp == NULL)
return NSERROR_NOMEM;
object->source_data = temp;
object->source_alloc = new_len;
}
/* Append this data chunk to source buffer */
memcpy(object->source_data + object->source_len, data, len);
object->source_len += len;
return NSERROR_OK;
}
/**
* Handle a query response
*
* \param proceed Whether to proceed with fetch
* \param cbpw Our context for query
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_query_handle_response(bool proceed, void *cbpw)
{
llcache_event event;
llcache_object *object = cbpw;
object->fetch.outstanding_query = false;
/* Refetch, using existing fetch parameters, if client allows us to */
if (proceed)
return llcache_object_refetch(object);
/* Invalidate cache-control data */
llcache_invalidate_cache_control_data(object);
/* Mark it complete */
object->fetch.state = LLCACHE_FETCH_COMPLETE;
/* Inform client(s) that object fetch failed */
event.type = LLCACHE_EVENT_ERROR;
/** \todo More appropriate error message */
event.data.msg = messages_get("FetchFailed");
return llcache_send_event_to_users(object, &event);
}
/**
* Handle an authentication request
*
* \param object Object being fetched
* \param realm Authentication realm
* \return NSERROR_OK on success, appropriate error otherwise.
*/
static nserror llcache_fetch_auth(llcache_object *object, const char *realm)
{
const char *auth;
nserror error = NSERROR_OK;
/* Abort fetch for this object */
fetch_abort(object->fetch.fetch);
object->fetch.fetch = NULL;
/* Invalidate cache-control data */
llcache_invalidate_cache_control_data(object);
/* Destroy headers */
llcache_destroy_headers(object);
/* If there was no realm, then default to the URL */
/** \todo If there was no WWW-Authenticate header, use response body */
if (realm == NULL)
realm = nsurl_access(object->url);
auth = urldb_get_auth_details(object->url, realm);
if (auth == NULL || object->fetch.tried_with_auth == true) {
/* No authentication details, or tried what we had, so ask */
object->fetch.tried_with_auth = false;
if (llcache->query_cb != NULL) {
llcache_query query;
/* Emit query for authentication details */
query.type = LLCACHE_QUERY_AUTH;
query.url = object->url;
query.data.auth.realm = realm;
object->fetch.outstanding_query = true;
error = llcache->query_cb(&query, llcache->query_cb_pw,
llcache_query_handle_response, object);
} else {
llcache_event event;
/* Mark object complete */
object->fetch.state = LLCACHE_FETCH_COMPLETE;
/* Inform client(s) that object fetch failed */
event.type = LLCACHE_EVENT_ERROR;
/** \todo More appropriate error message */
event.data.msg = messages_get("FetchFailed");
error = llcache_send_event_to_users(object, &event);
}
} else {
/* Flag that we've tried to refetch with credentials, so
* that if the fetch fails again, we ask the user again */
object->fetch.tried_with_auth = true;
error = llcache_object_refetch(object);
}
return error;
}
/**
* Handle a TLS certificate verification failure
*
* \param object Object being fetched
* \param certs Certificate chain
* \param num Number of certificates in chain
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_fetch_cert_error(llcache_object *object,
const struct ssl_cert_info *certs, size_t num)
{
nserror error = NSERROR_OK;
/* Fetch has been stopped, and destroyed. Invalidate object's pointer */
object->fetch.fetch = NULL;
/* Invalidate cache-control data */
llcache_invalidate_cache_control_data(object);
if (llcache->query_cb != NULL) {
llcache_query query;
/* Emit query for TLS */
query.type = LLCACHE_QUERY_SSL;
query.url = object->url;
query.data.ssl.certs = certs;
query.data.ssl.num = num;
object->fetch.outstanding_query = true;
error = llcache->query_cb(&query, llcache->query_cb_pw,
llcache_query_handle_response, object);
} else {
llcache_event event;
/* Mark object complete */
object->fetch.state = LLCACHE_FETCH_COMPLETE;
/* Inform client(s) that object fetch failed */
event.type = LLCACHE_EVENT_ERROR;
/** \todo More appropriate error message */
event.data.msg = messages_get("FetchFailed");
error = llcache_send_event_to_users(object, &event);
}
return error;
}
/**
* Handle a TLS connection setup failure
*
* \param object Object being fetched
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_fetch_ssl_error(llcache_object *object)
{
nserror error = NSERROR_OK;
/* Fetch has been stopped, and destroyed. Invalidate object's pointer */
object->fetch.fetch = NULL;
/* Invalidate cache-control data */
llcache_invalidate_cache_control_data(object);
if (object->fetch.tried_with_tls_downgrade == true) {
/* Have already tried to downgrade, so give up */
llcache_event event;
/* Mark object complete */
object->fetch.state = LLCACHE_FETCH_COMPLETE;
/* Inform client(s) that object fetch failed */
event.type = LLCACHE_EVENT_ERROR;
/** \todo More appropriate error message */
event.data.msg = messages_get("FetchFailed");
error = llcache_send_event_to_users(object, &event);
} else {
/* Flag that we've tried to downgrade, so that if the
* fetch fails again, we give up */
object->fetch.tried_with_tls_downgrade = true;
error = llcache_object_refetch(object);
}
return error;
}
/**
* Handler for fetch events
*
* \param msg Fetch event
* \param p Our private data
*/
static void llcache_fetch_callback(const fetch_msg *msg, void *p)
{
nserror error = NSERROR_OK;
llcache_object *object = p;
llcache_event event;
#ifdef LLCACHE_TRACE
LOG(("Fetch event %d for %p", msg->type, object));
#endif
switch (msg->type) {
case FETCH_HEADER:
/* Received a fetch header */
object->fetch.state = LLCACHE_FETCH_HEADERS;
error = llcache_fetch_process_header(object,
msg->data.header_or_data.buf,
msg->data.header_or_data.len);
break;
/* 3xx responses */
case FETCH_REDIRECT:
/* Request resulted in a redirect */
/* Release candidate, if any */
if (object->candidate != NULL) {
object->candidate->candidate_count--;
object->candidate = NULL;
}
error = llcache_fetch_redirect(object,
msg->data.redirect, &object);
break;
case FETCH_NOTMODIFIED:
/* Conditional request determined that cached object is fresh */
error = llcache_fetch_notmodified(object, &object);
break;
/* Normal 2xx state machine */
case FETCH_DATA:
/* Received some data */
if (object->fetch.state != LLCACHE_FETCH_DATA) {
/* On entry into this state, check if we need to
* invalidate the cache control data. We are guaranteed
* to have received all response headers.
*
* There are two cases in which we want to suppress
* cacheing of an object:
*
* 1) The HTTP response code is not 200 or 203
* 2) The request URI had a query string and the
* response headers did not provide an explicit
* object expiration time.
*/
long http_code = fetch_http_code(object->fetch.fetch);
if ((http_code != 200 && http_code != 203) ||
(object->has_query &&
(object->cache.max_age == INVALID_AGE &&
object->cache.expires == 0))) {
/* Invalidate cache control data */
llcache_invalidate_cache_control_data(object);
}
/* Release candidate, if any */
if (object->candidate != NULL) {
object->candidate->candidate_count--;
object->candidate = NULL;
}
}
object->fetch.state = LLCACHE_FETCH_DATA;
error = llcache_fetch_process_data(object,
msg->data.header_or_data.buf,
msg->data.header_or_data.len);
break;
case FETCH_FINISHED:
/* Finished fetching */
{
uint8_t *temp;
object->fetch.state = LLCACHE_FETCH_COMPLETE;
object->fetch.fetch = NULL;
/* Shrink source buffer to required size */
temp = realloc(object->source_data,
object->source_len);
/* If source_len is 0, then temp may be NULL */
if (temp != NULL || object->source_len == 0) {
object->source_data = temp;
object->source_alloc = object->source_len;
}
llcache_object_cache_update(object);
}
break;
/* Out-of-band information */
case FETCH_ERROR:
/* An error occurred while fetching */
/* The fetch has has already been cleaned up by the fetcher */
object->fetch.state = LLCACHE_FETCH_COMPLETE;
object->fetch.fetch = NULL;
/* Release candidate, if any */
if (object->candidate != NULL) {
object->candidate->candidate_count--;
object->candidate = NULL;
}
/* Invalidate cache control data */
llcache_invalidate_cache_control_data(object);
/** \todo Consider using errorcode for something */
event.type = LLCACHE_EVENT_ERROR;
event.data.msg = msg->data.error;
error = llcache_send_event_to_users(object, &event);
break;
case FETCH_PROGRESS:
/* Progress update */
event.type = LLCACHE_EVENT_PROGRESS;
event.data.msg = msg->data.progress;
error = llcache_send_event_to_users(object, &event);
break;
/* Events requiring action */
case FETCH_AUTH:
/* Need Authentication */
/* Release candidate, if any */
if (object->candidate != NULL) {
object->candidate->candidate_count--;
object->candidate = NULL;
}
error = llcache_fetch_auth(object, msg->data.auth.realm);
break;
case FETCH_CERT_ERR:
/* Something went wrong when validating TLS certificates */
/* Release candidate, if any */
if (object->candidate != NULL) {
object->candidate->candidate_count--;
object->candidate = NULL;
}
error = llcache_fetch_cert_error(object,
msg->data.cert_err.certs,
msg->data.cert_err.num_certs);
break;
case FETCH_SSL_ERR:
/* TLS connection setup failed */
/* Release candidate, if any */
if (object->candidate != NULL) {
object->candidate->candidate_count--;
object->candidate = NULL;
}
error = llcache_fetch_ssl_error(object);
break;
}
/* Deal with any errors reported by event handlers */
if (error != NSERROR_OK) {
if (object->fetch.fetch != NULL) {
fetch_abort(object->fetch.fetch);
object->fetch.fetch = NULL;
/* Invalidate cache control data */
llcache_invalidate_cache_control_data(object);
object->fetch.state = LLCACHE_FETCH_COMPLETE;
}
return;
}
}
/**
* Find a user of a low-level cache object
*
* \param handle External cache handle to search for
* \return Pointer to corresponding user, or NULL if not found
*/
static llcache_object_user *llcache_object_find_user(const llcache_handle *handle)
{
llcache_object_user *user;
assert(handle->object != NULL);
for (user = handle->object->users; user != NULL; user = user->next) {
if (user->handle == handle)
break;
}
return user;
}
/**
* Remove a low-level cache object from a cache list
*
* \param object Object to remove
* \param list List to remove from
* \return NSERROR_OK
*/
static nserror llcache_object_remove_from_list(llcache_object *object,
llcache_object **list)
{
if (object == *list)
*list = object->next;
else
object->prev->next = object->next;
if (object->next != NULL)
object->next->prev = object->prev;
return NSERROR_OK;
}
/**
* Determine if a low-level cache object resides in a given list
*
* \param object Object to search for
* \param list List to search in
* \return True if object resides in list, false otherwise
*/
static bool llcache_object_in_list(const llcache_object *object,
const llcache_object *list)
{
while (list != NULL) {
if (list == object)
break;
list = list->next;
}
return list != NULL;
}
/**
* Notify users of an object's current state
*
* \param object Object to notify users about
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_object_notify_users(llcache_object *object)
{
nserror error;
llcache_object_user *user, *next_user;
llcache_event event;
#ifdef LLCACHE_TRACE
bool emitted_notify = false;
#endif
/**
* State transitions and event emission for users.
* Rows: user state. Cols: object state.
*
* User\Obj INIT HEADERS DATA COMPLETE
* INIT - T T* T*
* HEADERS - - T T*
* DATA - - M T
* COMPLETE - - - -
*
* T => transition user to object state
* M => no transition required, but may need to emit event
*
* The transitions marked with an asterisk can be removed by moving
* the user context into the subsequent state and then reevaluating.
*
* Events are issued as follows:
*
* HAD_HEADERS: on transition from HEADERS -> DATA state
* HAD_DATA : in DATA state, whenever there's new source data
* DONE : on transition from DATA -> COMPLETE state
*/
for (user = object->users; user != NULL; user = next_user) {
/* Emit necessary events to bring the user up-to-date */
llcache_handle *handle = user->handle;
const llcache_fetch_state objstate = object->fetch.state;
/* Flag that this user is the current iteration target
* in case the client attempts to destroy it underneath us */
user->iterator_target = true;
/* A note on the computation of next_user:
*
* Within this loop, we may make a number of calls to
* client code. Our contract with clients is that they
* can do whatever they like from within their callback
* handlers. This is so that we limit the pain of
* reentrancy to this module alone.
*
* One of the things a client can do from within its
* callback handler is to remove users from this object's
* user list. In the common case, the user they attempt
* to remove is the current iteration target, and we
* already protect against that causing problems here.
* However, no such protection exists if the client
* attempts to remove other users from this object's
* user list.
*
* Therefore, we cannot compute next_user up-front
* and expect it to remain valid across calls to
* client code (as the identity of the next user
* in the list may change underneath us). Instead,
* we must compute next_user at the point where we
* are about to cause another iteration of this loop
* (i.e. at the very end, and also at the points where
* continue is used)
*/
#ifdef LLCACHE_TRACE
if (handle->state != objstate) {
if (emitted_notify == false) {
LOG(("Notifying users of %p", object));
emitted_notify = true;
}
LOG(("User %p state: %d Object state: %d",
user, handle->state, objstate));
}
#endif
/* User: INIT, Obj: HEADERS, DATA, COMPLETE => User->HEADERS */
if (handle->state == LLCACHE_FETCH_INIT &&
objstate > LLCACHE_FETCH_INIT) {
handle->state = LLCACHE_FETCH_HEADERS;
}
/* User: HEADERS, Obj: DATA, COMPLETE => User->DATA */
if (handle->state == LLCACHE_FETCH_HEADERS &&
objstate > LLCACHE_FETCH_HEADERS) {
handle->state = LLCACHE_FETCH_DATA;
/* Emit HAD_HEADERS event */
event.type = LLCACHE_EVENT_HAD_HEADERS;
error = handle->cb(handle, &event, handle->pw);
if (user->queued_for_delete) {
next_user = user->next;
llcache_object_remove_user(object, user);
llcache_object_user_destroy(user);
if (error != NSERROR_OK)
return error;
continue;
} else if (error == NSERROR_NEED_DATA) {
/* User requested replay */
handle->state = LLCACHE_FETCH_HEADERS;
/* Continue with the next user -- we'll
* reemit the event next time round */
user->iterator_target = false;
next_user = user->next;
continue;
} else if (error != NSERROR_OK) {
user->iterator_target = false;
return error;
}
}
/* User: DATA, Obj: DATA, COMPLETE, more source available */
if (handle->state == LLCACHE_FETCH_DATA &&
objstate >= LLCACHE_FETCH_DATA &&
object->source_len > handle->bytes) {
size_t orig_handle_read;
/* Construct HAD_DATA event */
event.type = LLCACHE_EVENT_HAD_DATA;
event.data.data.buf =
object->source_data + handle->bytes;
event.data.data.len =
object->source_len - handle->bytes;
/* Update record of last byte emitted */
if (object->fetch.flags &
LLCACHE_RETRIEVE_STREAM_DATA) {
/* Streaming, so reset to zero to
* minimise amount of cached source data.
* Additionally, we don't support replay
* when streaming. */
orig_handle_read = 0;
handle->bytes = object->source_len = 0;
} else {
orig_handle_read = handle->bytes;
handle->bytes = object->source_len;
}
/* Emit event */
error = handle->cb(handle, &event, handle->pw);
if (user->queued_for_delete) {
next_user = user->next;
llcache_object_remove_user(object, user);
llcache_object_user_destroy(user);
if (error != NSERROR_OK)
return error;
continue;
} else if (error == NSERROR_NEED_DATA) {
/* User requested replay */
handle->bytes = orig_handle_read;
/* Continue with the next user -- we'll
* reemit the data next time round */
user->iterator_target = false;
next_user = user->next;
continue;
} else if (error != NSERROR_OK) {
user->iterator_target = false;
return error;
}
}
/* User: DATA, Obj: COMPLETE => User->COMPLETE */
if (handle->state == LLCACHE_FETCH_DATA &&
objstate > LLCACHE_FETCH_DATA) {
handle->state = LLCACHE_FETCH_COMPLETE;
/* Emit DONE event */
event.type = LLCACHE_EVENT_DONE;
error = handle->cb(handle, &event, handle->pw);
if (user->queued_for_delete) {
next_user = user->next;
llcache_object_remove_user(object, user);
llcache_object_user_destroy(user);
if (error != NSERROR_OK)
return error;
continue;
} else if (error == NSERROR_NEED_DATA) {
/* User requested replay */
handle->state = LLCACHE_FETCH_DATA;
/* Continue with the next user -- we'll
* reemit the event next time round */
user->iterator_target = false;
next_user = user->next;
continue;
} else if (error != NSERROR_OK) {
user->iterator_target = false;
return error;
}
}
/* No longer the target of an iterator */
user->iterator_target = false;
next_user = user->next;
}
return NSERROR_OK;
}
/**
* Make a snapshot of the current state of an llcache_object.
*
* This has the side-effect of the new object being non-cacheable,
* also not-fetching and not a candidate for any other object.
*
* Also note that this new object has no users and at least one
* should be assigned to it before llcache_clean is entered or it
* will be immediately cleaned up.
*
* \param object The object to take a snapshot of
* \param snapshot Pointer to receive snapshot of \a object
* \return NSERROR_OK on success, appropriate error otherwise
*/
static nserror llcache_object_snapshot(llcache_object *object,
llcache_object **snapshot)
{
llcache_object *newobj;
nserror error;
error = llcache_object_new(object->url, &newobj);
if (error != NSERROR_OK)
return error;
newobj->has_query = object->has_query;
newobj->source_alloc = newobj->source_len = object->source_len;
if (object->source_len > 0) {
newobj->source_data = malloc(newobj->source_alloc);
if (newobj->source_data == NULL) {
llcache_object_destroy(newobj);
return NSERROR_NOMEM;
}
memcpy(newobj->source_data, object->source_data,
newobj->source_len);
}
if (object->num_headers > 0) {
newobj->headers = calloc(sizeof(llcache_header),
object->num_headers);
if (newobj->headers == NULL) {
llcache_object_destroy(newobj);
return NSERROR_NOMEM;
}
while (newobj->num_headers < object->num_headers) {
llcache_header *nh =
&(newobj->headers[newobj->num_headers]);
llcache_header *oh =
&(object->headers[newobj->num_headers]);
newobj->num_headers += 1;
nh->name = strdup(oh->name);
nh->value = strdup(oh->value);
if (nh->name == NULL || nh->value == NULL) {
llcache_object_destroy(newobj);
return NSERROR_NOMEM;
}
}
}
newobj->fetch.state = LLCACHE_FETCH_COMPLETE;
*snapshot = newobj;
return NSERROR_OK;
}
/******************************************************************************
* Public API *
******************************************************************************/
/**
* Attempt to clean the cache
*/
/* Exported interface documented in llcache.h */
void llcache_clean(void)
{
llcache_object *object, *next;
uint32_t llcache_size = 0;
int remaining_lifetime;
#ifdef LLCACHE_TRACE
LOG(("Attempting cache clean"));
#endif
/* Candidates for cleaning are (in order of priority):
*
* 1) Uncacheable objects with no users
* 2) Stale cacheable objects with no users or pending fetches
* 3) Fresh cacheable objects with no users or pending fetches
*/
/* 1) Uncacheable objects with no users or fetches */
for (object = llcache->uncached_objects; object != NULL; object = next) {
next = object->next;
/* The candidate count of uncacheable objects is always 0 */
if ((object->users == NULL) &&
(object->candidate_count == 0) &&
(object->fetch.fetch == NULL) &&
(object->fetch.outstanding_query == false)) {
#ifdef LLCACHE_TRACE
LOG(("Found victim %p", object));
#endif
llcache_object_remove_from_list(object,
&llcache->uncached_objects);
llcache_object_destroy(object);
} else {
llcache_size += object->source_len + sizeof(*object);
}
}
/* 2) Stale cacheable objects with no users or pending fetches */
for (object = llcache->cached_objects; object != NULL; object = next) {
next = object->next;
remaining_lifetime = llcache_object_rfc2616_remaining_lifetime(&object->cache);
if ((object->users == NULL) &&
(object->candidate_count == 0) &&
(object->fetch.fetch == NULL) &&
(object->fetch.outstanding_query == false)) {
if (remaining_lifetime > 0) {
/* object is fresh */
llcache_size += object->source_len + sizeof(*object);
} else {
/* object is not fresh */
#ifdef LLCACHE_TRACE
LOG(("Found stale cacheable object (%p) with no users or pending fetches", object));
#endif
llcache_object_remove_from_list(object,
&llcache->cached_objects);
llcache_object_destroy(object);
}
} else {
llcache_size += object->source_len + sizeof(*object);
}
}
/* 3) Fresh cacheable objects with no users or pending
* fetches, only if the cache exceeds the configured size.
*/
if (llcache->limit < llcache_size) {
for (object = llcache->cached_objects; object != NULL;
object = next) {
next = object->next;
if ((object->users == NULL) &&
(object->candidate_count == 0) &&
(object->fetch.fetch == NULL) &&
(object->fetch.outstanding_query == false)) {
#ifdef LLCACHE_TRACE
LOG(("Found victim %p", object));
#endif
llcache_size -=
object->source_len + sizeof(*object);
llcache_object_remove_from_list(object,
&llcache->cached_objects);
llcache_object_destroy(object);
}
}
}
#ifdef LLCACHE_TRACE
LOG(("Size: %u", llcache_size));
#endif
}
/* See llcache.h for documentation */
nserror
llcache_initialise(llcache_query_callback cb, void *pw, uint32_t llcache_limit)
{
llcache = calloc(1, sizeof(struct llcache_s));
if (llcache == NULL) {
return NSERROR_NOMEM;
}
llcache->query_cb = cb;
llcache->query_cb_pw = pw;
llcache->limit = llcache_limit;
/* Create static scheme strings */
if (lwc_intern_string("file", SLEN("file"),
&llcache_file_lwc) != lwc_error_ok)
return NSERROR_NOMEM;
if (lwc_intern_string("about", SLEN("about"),
&llcache_about_lwc) != lwc_error_ok)
return NSERROR_NOMEM;
if (lwc_intern_string("resource", SLEN("resource"),
&llcache_resource_lwc) != lwc_error_ok)
return NSERROR_NOMEM;
LOG(("llcache initialised with a limit of %d bytes", llcache_limit));
return NSERROR_OK;
}
/* See llcache.h for documentation */
void llcache_finalise(void)
{
llcache_object *object, *next;
/* Clean uncached objects */
for (object = llcache->uncached_objects; object != NULL; object = next) {
llcache_object_user *user, *next_user;
next = object->next;
for (user = object->users; user != NULL; user = next_user) {
next_user = user->next;
if (user->handle != NULL)
free(user->handle);
free(user);
}
/* Fetch system has already been destroyed */
object->fetch.fetch = NULL;
llcache_object_destroy(object);
}
/* Clean cached objects */
for (object = llcache->cached_objects; object != NULL; object = next) {
llcache_object_user *user, *next_user;
next = object->next;
for (user = object->users; user != NULL; user = next_user) {
next_user = user->next;
if (user->handle != NULL)
free(user->handle);
free(user);
}
/* Fetch system has already been destroyed */
object->fetch.fetch = NULL;
llcache_object_destroy(object);
}
/* Unref static scheme lwc strings */
lwc_string_unref(llcache_file_lwc);
lwc_string_unref(llcache_about_lwc);
lwc_string_unref(llcache_resource_lwc);
free(llcache);
llcache = NULL;
}
/* See llcache.h for documentation */
nserror llcache_poll(void)
{
llcache_object *object;
fetch_poll();
/* Catch new users up with state of objects */
for (object = llcache->cached_objects; object != NULL;
object = object->next) {
llcache_object_notify_users(object);
}
for (object = llcache->uncached_objects; object != NULL;
object = object->next) {
llcache_object_notify_users(object);
}
return NSERROR_OK;
}
/* See llcache.h for documentation */
nserror llcache_handle_retrieve(nsurl *url, uint32_t flags,
nsurl *referer, const llcache_post_data *post,
llcache_handle_callback cb, void *pw,
llcache_handle **result)
{
nserror error;
llcache_object_user *user;
llcache_object *object;
/* Can we fetch this URL at all? */
if (fetch_can_fetch(url) == false)
return NSERROR_NO_FETCH_HANDLER;
/* Create a new object user */
error = llcache_object_user_new(cb, pw, &user);
if (error != NSERROR_OK)
return error;
/* Retrieve a suitable object from the cache,
* creating a new one if needed. */
error = llcache_object_retrieve(url, flags, referer, post, 0, &object);
if (error != NSERROR_OK) {
llcache_object_user_destroy(user);
return error;
}
/* Add user to object */
llcache_object_add_user(object, user);
*result = user->handle;
return NSERROR_OK;
}
/* See llcache.h for documentation */
nserror llcache_handle_change_callback(llcache_handle *handle,
llcache_handle_callback cb, void *pw)
{
handle->cb = cb;
handle->pw = pw;
return NSERROR_OK;
}
/* See llcache.h for documentation */
nserror llcache_handle_release(llcache_handle *handle)
{
nserror error = NSERROR_OK;
llcache_object *object = handle->object;
llcache_object_user *user = llcache_object_find_user(handle);
assert(user != NULL);
if (user->iterator_target) {
/* Can't remove / delete user object if it's
* the target of an iterator */
user->queued_for_delete = true;
} else {
/* Remove the user from the object and destroy it */
error = llcache_object_remove_user(object, user);
if (error == NSERROR_OK) {
error = llcache_object_user_destroy(user);
}
}
return error;
}
/* See llcache.h for documentation */
nserror llcache_handle_clone(llcache_handle *handle, llcache_handle **result)
{
nserror error;
llcache_object_user *newuser;
error = llcache_object_user_new(handle->cb, handle->pw, &newuser);
if (error == NSERROR_OK) {
llcache_object_add_user(handle->object, newuser);
newuser->handle->state = handle->state;
*result = newuser->handle;
}
return error;
}
/* See llcache.h for documentation */
nserror llcache_handle_abort(llcache_handle *handle)
{
llcache_object_user *user = llcache_object_find_user(handle);
llcache_object *object = handle->object, *newobject;
nserror error = NSERROR_OK;
bool all_alone = true;
/* Determine if we are the only user */
if (user->prev != NULL)
all_alone = false;
if (user->next != NULL)
all_alone = false;
if (all_alone == false) {
/* We must snapshot this object */
error = llcache_object_snapshot(object, &newobject);
if (error != NSERROR_OK)
return error;
/* Move across to the new object */
if (user->iterator_target) {
/* User is current iterator target, clone it */
llcache_object_user *newuser =
calloc(1, sizeof(llcache_object_user));
if (newuser == NULL) {
llcache_object_destroy(newobject);
return NSERROR_NOMEM;
}
/* Move handle across to clone */
newuser->handle = user->handle;
user->handle = NULL;
/* Mark user as needing deletion */
user->queued_for_delete = true;
llcache_object_add_user(newobject, newuser);
} else {
llcache_object_remove_user(object, user);
llcache_object_add_user(newobject, user);
}
/* Add new object to uncached list */
llcache_object_add_to_list(newobject,
&llcache->uncached_objects);
} else {
/* We're the only user, so abort any fetch in progress */
if (object->fetch.fetch != NULL) {
fetch_abort(object->fetch.fetch);
object->fetch.fetch = NULL;
}
object->fetch.state = LLCACHE_FETCH_COMPLETE;
/* Invalidate cache control data */
llcache_invalidate_cache_control_data(object);
}
return error;
}
/* See llcache.h for documentation */
nserror llcache_handle_force_stream(llcache_handle *handle)
{
llcache_object_user *user = llcache_object_find_user(handle);
llcache_object *object = handle->object;
/* Cannot stream if there are multiple users */
if (user->prev != NULL || user->next != NULL)
return NSERROR_OK;
/* Forcibly uncache this object */
if (llcache_object_in_list(object, llcache->cached_objects)) {
llcache_object_remove_from_list(object,
&llcache->cached_objects);
llcache_object_add_to_list(object, &llcache->uncached_objects);
}
object->fetch.flags |= LLCACHE_RETRIEVE_STREAM_DATA;
return NSERROR_OK;
}
/* See llcache.h for documentation */
nserror llcache_handle_invalidate_cache_data(llcache_handle *handle)
{
if (handle->object != NULL && handle->object->fetch.fetch == NULL &&
handle->object->cache.no_cache ==
LLCACHE_VALIDATE_FRESH) {
handle->object->cache.no_cache = LLCACHE_VALIDATE_ONCE;
}
return NSERROR_OK;
}
/* See llcache.h for documentation */
nsurl *llcache_handle_get_url(const llcache_handle *handle)
{
return handle->object != NULL ? handle->object->url : NULL;
}
/* See llcache.h for documentation */
const uint8_t *llcache_handle_get_source_data(const llcache_handle *handle,
size_t *size)
{
*size = handle->object != NULL ? handle->object->source_len : 0;
return handle->object != NULL ? handle->object->source_data : NULL;
}
/* See llcache.h for documentation */
const char *llcache_handle_get_header(const llcache_handle *handle,
const char *key)
{
const llcache_object *object = handle->object;
size_t i;
if (object == NULL)
return NULL;
/* About as trivial as possible */
for (i = 0; i < object->num_headers; i++) {
if (strcasecmp(key, object->headers[i].name) == 0)
return object->headers[i].value;
}
return NULL;
}
/* See llcache.h for documentation */
bool llcache_handle_references_same_object(const llcache_handle *a,
const llcache_handle *b)
{
return a->object == b->object;
}