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Diffstat (limited to '')
| -rw-r--r-- | modules/cache/cache_util.c | 1344 |
1 files changed, 1344 insertions, 0 deletions
diff --git a/modules/cache/cache_util.c b/modules/cache/cache_util.c new file mode 100644 index 0000000..fc36431 --- /dev/null +++ b/modules/cache/cache_util.c @@ -0,0 +1,1344 @@ +/* Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "mod_cache.h" + +#include "cache_util.h" +#include <ap_provider.h> + +APLOG_USE_MODULE(cache); + +/* -------------------------------------------------------------- */ + +extern APR_OPTIONAL_FN_TYPE(ap_cache_generate_key) *cache_generate_key; + +extern module AP_MODULE_DECLARE_DATA cache_module; + +/* Determine if "url" matches the hostname, scheme and port and path + * in "filter". All but the path comparisons are case-insensitive. + */ +static int uri_meets_conditions(const apr_uri_t *filter, const apr_size_t pathlen, + const apr_uri_t *url, const char *path) +{ + /* Scheme, hostname port and local part. The filter URI and the + * URI we test may have the following shapes: + * /<path> + * <scheme>[:://<hostname>[:<port>][/<path>]] + * That is, if there is no scheme then there must be only the path, + * and we check only the path; if there is a scheme, we check the + * scheme for equality, and then if present we match the hostname, + * and then if present match the port, and finally the path if any. + * + * Note that this means that "/<path>" only matches local paths, + * and to match proxied paths one *must* specify the scheme. + */ + + /* Is the filter is just for a local path or a proxy URI? */ + if (!filter->scheme) { + if (url->scheme || url->hostname) { + return 0; + } + } + else { + /* The URI scheme must be present and identical except for case. */ + if (!url->scheme || ap_cstr_casecmp(filter->scheme, url->scheme)) { + return 0; + } + + /* If the filter hostname is null or empty it matches any hostname, + * if it begins with a "*" it matches the _end_ of the URI hostname + * excluding the "*", if it begins with a "." it matches the _end_ + * of the URI * hostname including the ".", otherwise it must match + * the URI hostname exactly. */ + + if (filter->hostname && filter->hostname[0]) { + if (filter->hostname[0] == '.') { + const size_t fhostlen = strlen(filter->hostname); + const size_t uhostlen = url->hostname ? strlen(url->hostname) : 0; + + if (fhostlen > uhostlen + || (url->hostname + && strcasecmp(filter->hostname, + url->hostname + uhostlen - fhostlen))) { + return 0; + } + } + else if (filter->hostname[0] == '*') { + const size_t fhostlen = strlen(filter->hostname + 1); + const size_t uhostlen = url->hostname ? strlen(url->hostname) : 0; + + if (fhostlen > uhostlen + || (url->hostname + && strcasecmp(filter->hostname + 1, + url->hostname + uhostlen - fhostlen))) { + return 0; + } + } + else if (!url->hostname || strcasecmp(filter->hostname, url->hostname)) { + return 0; + } + } + + /* If the filter port is empty it matches any URL port. + * If the filter or URL port are missing, or the URL port is + * empty, they default to the port for their scheme. */ + + if (!(filter->port_str && !filter->port_str[0])) { + /* NOTE: ap_port_of_scheme will return 0 if given NULL input */ + const unsigned fport = filter->port_str ? filter->port + : apr_uri_port_of_scheme(filter->scheme); + const unsigned uport = (url->port_str && url->port_str[0]) + ? url->port : apr_uri_port_of_scheme(url->scheme); + + if (fport != uport) { + return 0; + } + } + } + + /* For HTTP caching purposes, an empty (NULL) path is equivalent to + * a single "/" path. RFCs 3986/2396 + */ + if (!path) { + if (*filter->path == '/' && pathlen == 1) { + return 1; + } + else { + return 0; + } + } + + /* Url has met all of the filter conditions so far, determine + * if the paths match. + */ + return !strncmp(filter->path, path, pathlen); +} + +int cache_use_early_url(request_rec *r) +{ + cache_server_conf *conf; + + if (r->proxyreq == PROXYREQ_PROXY) { + return 1; + } + + conf = ap_get_module_config(r->server->module_config, &cache_module); + if (conf->quick) { + return 1; + } + + return 0; +} + +static cache_provider_list *get_provider(request_rec *r, struct cache_enable *ent, + cache_provider_list *providers) +{ + /* Fetch from global config and add to the list. */ + cache_provider *provider; + provider = ap_lookup_provider(CACHE_PROVIDER_GROUP, ent->type, + "0"); + if (!provider) { + /* Log an error! */ + } + else { + cache_provider_list *newp; + newp = apr_pcalloc(r->pool, sizeof(cache_provider_list)); + newp->provider_name = ent->type; + newp->provider = provider; + + if (!providers) { + providers = newp; + } + else { + cache_provider_list *last = providers; + + while (last->next) { + if (last->provider == provider) { + return providers; + } + last = last->next; + } + if (last->provider == provider) { + return providers; + } + last->next = newp; + } + } + + return providers; +} + +cache_provider_list *cache_get_providers(request_rec *r, + cache_server_conf *conf) +{ + cache_dir_conf *dconf = ap_get_module_config(r->per_dir_config, &cache_module); + cache_provider_list *providers = NULL; + const char *path; + int i; + + /* per directory cache disable */ + if (dconf->disable) { + return NULL; + } + + path = cache_use_early_url(r) ? r->parsed_uri.path : r->uri; + + /* global cache disable */ + for (i = 0; i < conf->cachedisable->nelts; i++) { + struct cache_disable *ent = + (struct cache_disable *)conf->cachedisable->elts; + if (uri_meets_conditions(&ent[i].url, ent[i].pathlen, + &r->parsed_uri, path)) { + /* Stop searching now. */ + return NULL; + } + } + + /* loop through all the per directory cacheenable entries */ + for (i = 0; i < dconf->cacheenable->nelts; i++) { + struct cache_enable *ent = + (struct cache_enable *)dconf->cacheenable->elts; + providers = get_provider(r, &ent[i], providers); + } + + /* loop through all the global cacheenable entries */ + for (i = 0; i < conf->cacheenable->nelts; i++) { + struct cache_enable *ent = + (struct cache_enable *)conf->cacheenable->elts; + if (uri_meets_conditions(&ent[i].url, ent[i].pathlen, + &r->parsed_uri, path)) { + providers = get_provider(r, &ent[i], providers); + } + } + + return providers; +} + + +/* do a HTTP/1.1 age calculation */ +CACHE_DECLARE(apr_int64_t) ap_cache_current_age(cache_info *info, + const apr_time_t age_value, + apr_time_t now) +{ + apr_time_t apparent_age, corrected_received_age, response_delay, + corrected_initial_age, resident_time, current_age, + age_value_usec; + + age_value_usec = apr_time_from_sec(age_value); + + /* Perform an HTTP/1.1 age calculation. (RFC2616 13.2.3) */ + + apparent_age = MAX(0, info->response_time - info->date); + corrected_received_age = MAX(apparent_age, age_value_usec); + response_delay = info->response_time - info->request_time; + corrected_initial_age = corrected_received_age + response_delay; + resident_time = now - info->response_time; + current_age = corrected_initial_age + resident_time; + + if (current_age < 0) { + current_age = 0; + } + + return apr_time_sec(current_age); +} + +/** + * Try obtain a cache wide lock on the given cache key. + * + * If we return APR_SUCCESS, we obtained the lock, and we are clear to + * proceed to the backend. If we return APR_EEXIST, then the lock is + * already locked, someone else has gone to refresh the backend data + * already, so we must return stale data with a warning in the mean + * time. If we return anything else, then something has gone pear + * shaped, and we allow the request through to the backend regardless. + * + * This lock is created from the request pool, meaning that should + * something go wrong and the lock isn't deleted on return of the + * request headers from the backend for whatever reason, at worst the + * lock will be cleaned up when the request dies or finishes. + * + * If something goes truly bananas and the lock isn't deleted when the + * request dies, the lock will be trashed when its max-age is reached, + * or when a request arrives containing a Cache-Control: no-cache. At + * no point is it possible for this lock to permanently deny access to + * the backend. + */ +apr_status_t cache_try_lock(cache_server_conf *conf, cache_request_rec *cache, + request_rec *r) +{ + apr_status_t status; + const char *lockname; + const char *path; + char dir[5]; + apr_time_t now = apr_time_now(); + apr_finfo_t finfo; + apr_file_t *lockfile; + void *dummy; + + finfo.mtime = 0; + + if (!conf || !conf->lock || !conf->lockpath) { + /* no locks configured, leave */ + return APR_SUCCESS; + } + + /* lock already obtained earlier? if so, success */ + apr_pool_userdata_get(&dummy, CACHE_LOCKFILE_KEY, r->pool); + if (dummy) { + return APR_SUCCESS; + } + + /* create the key if it doesn't exist */ + if (!cache->key) { + cache_handle_t *h; + /* + * Try to use the key of a possible open but stale cache + * entry if we have one. + */ + if (cache->handle != NULL) { + h = cache->handle; + } + else { + h = cache->stale_handle; + } + if ((h != NULL) && + (h->cache_obj != NULL) && + (h->cache_obj->key != NULL)) { + cache->key = apr_pstrdup(r->pool, h->cache_obj->key); + } + else { + cache_generate_key(r, r->pool, &cache->key); + } + } + + /* create a hashed filename from the key, and save it for later */ + lockname = ap_cache_generate_name(r->pool, 0, 0, cache->key); + + /* lock files represent discrete just-went-stale URLs "in flight", so + * we support a simple two level directory structure, more is overkill. + */ + dir[0] = '/'; + dir[1] = lockname[0]; + dir[2] = '/'; + dir[3] = lockname[1]; + dir[4] = 0; + + /* make the directories */ + path = apr_pstrcat(r->pool, conf->lockpath, dir, NULL); + if (APR_SUCCESS != (status = apr_dir_make_recursive(path, + APR_UREAD|APR_UWRITE|APR_UEXECUTE, r->pool))) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(00778) + "Could not create a cache lock directory: %s", + path); + return status; + } + lockname = apr_pstrcat(r->pool, path, "/", lockname, NULL); + apr_pool_userdata_set(lockname, CACHE_LOCKNAME_KEY, NULL, r->pool); + + /* is an existing lock file too old? */ + status = apr_stat(&finfo, lockname, + APR_FINFO_MTIME | APR_FINFO_NLINK, r->pool); + if (!(APR_STATUS_IS_ENOENT(status)) && APR_SUCCESS != status) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(00779) + "Could not stat a cache lock file: %s", + lockname); + return status; + } + if ((status == APR_SUCCESS) && (((now - finfo.mtime) > conf->lockmaxage) + || (now < finfo.mtime))) { + ap_log_rerror(APLOG_MARK, APLOG_INFO, status, r, APLOGNO(00780) + "Cache lock file for '%s' too old, removing: %s", + r->uri, lockname); + apr_file_remove(lockname, r->pool); + } + + /* try obtain a lock on the file */ + if (APR_SUCCESS == (status = apr_file_open(&lockfile, lockname, + APR_WRITE | APR_CREATE | APR_EXCL | APR_DELONCLOSE, + APR_UREAD | APR_UWRITE, r->pool))) { + apr_pool_userdata_set(lockfile, CACHE_LOCKFILE_KEY, NULL, r->pool); + } + return status; + +} + +/** + * Remove the cache lock, if present. + * + * First, try to close the file handle, whose delete-on-close should + * kill the file. Otherwise, just delete the file by name. + * + * If no lock name has yet been calculated, do the calculation of the + * lock name first before trying to delete the file. + * + * If an optional bucket brigade is passed, the lock will only be + * removed if the bucket brigade contains an EOS bucket. + */ +apr_status_t cache_remove_lock(cache_server_conf *conf, + cache_request_rec *cache, request_rec *r, apr_bucket_brigade *bb) +{ + void *dummy; + const char *lockname; + + if (!conf || !conf->lock || !conf->lockpath) { + /* no locks configured, leave */ + return APR_SUCCESS; + } + if (bb) { + apr_bucket *e; + int eos_found = 0; + for (e = APR_BRIGADE_FIRST(bb); + e != APR_BRIGADE_SENTINEL(bb); + e = APR_BUCKET_NEXT(e)) + { + if (APR_BUCKET_IS_EOS(e)) { + eos_found = 1; + break; + } + } + if (!eos_found) { + /* no eos found in brigade, don't delete anything just yet, + * we are not done. + */ + return APR_SUCCESS; + } + } + apr_pool_userdata_get(&dummy, CACHE_LOCKFILE_KEY, r->pool); + if (dummy) { + return apr_file_close((apr_file_t *)dummy); + } + apr_pool_userdata_get(&dummy, CACHE_LOCKNAME_KEY, r->pool); + lockname = (const char *)dummy; + if (!lockname) { + char dir[5]; + + /* create the key if it doesn't exist */ + if (!cache->key) { + cache_generate_key(r, r->pool, &cache->key); + } + + /* create a hashed filename from the key, and save it for later */ + lockname = ap_cache_generate_name(r->pool, 0, 0, cache->key); + + /* lock files represent discrete just-went-stale URLs "in flight", so + * we support a simple two level directory structure, more is overkill. + */ + dir[0] = '/'; + dir[1] = lockname[0]; + dir[2] = '/'; + dir[3] = lockname[1]; + dir[4] = 0; + + lockname = apr_pstrcat(r->pool, conf->lockpath, dir, "/", lockname, NULL); + } + return apr_file_remove(lockname, r->pool); +} + +int ap_cache_check_no_cache(cache_request_rec *cache, request_rec *r) +{ + + cache_server_conf *conf = + (cache_server_conf *)ap_get_module_config(r->server->module_config, + &cache_module); + + /* + * At this point, we may have data cached, but the request may have + * specified that cached data may not be used in a response. + * + * This is covered under RFC2616 section 14.9.4 (Cache Revalidation and + * Reload Controls). + * + * - RFC2616 14.9.4 End to end reload, Cache-Control: no-cache, or Pragma: + * no-cache. The server MUST NOT use a cached copy when responding to such + * a request. + */ + + /* This value comes from the client's initial request. */ + if (!cache->control_in.parsed) { + const char *cc_req = cache_table_getm(r->pool, r->headers_in, + "Cache-Control"); + const char *pragma = cache_table_getm(r->pool, r->headers_in, "Pragma"); + ap_cache_control(r, &cache->control_in, cc_req, pragma, r->headers_in); + } + + if (cache->control_in.no_cache) { + + if (!conf->ignorecachecontrol) { + return 0; + } + else { + ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r, APLOGNO(02657) + "Incoming request is asking for an uncached version of " + "%s, but we have been configured to ignore it and serve " + "cached content anyway", r->unparsed_uri); + } + } + + return 1; +} + +int ap_cache_check_no_store(cache_request_rec *cache, request_rec *r) +{ + + cache_server_conf *conf = + (cache_server_conf *)ap_get_module_config(r->server->module_config, + &cache_module); + + /* + * At this point, we may have data cached, but the request may have + * specified that cached data may not be used in a response. + * + * - RFC2616 14.9.2 What May be Stored by Caches. If Cache-Control: + * no-store arrives, do not serve from or store to the cache. + */ + + /* This value comes from the client's initial request. */ + if (!cache->control_in.parsed) { + const char *cc_req = cache_table_getm(r->pool, r->headers_in, + "Cache-Control"); + const char *pragma = cache_table_getm(r->pool, r->headers_in, "Pragma"); + ap_cache_control(r, &cache->control_in, cc_req, pragma, r->headers_in); + } + + if (cache->control_in.no_store) { + + if (!conf->ignorecachecontrol) { + /* We're not allowed to serve a cached copy */ + return 0; + } + else { + ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r, APLOGNO(02658) + "Incoming request is asking for a no-store version of " + "%s, but we have been configured to ignore it and serve " + "cached content anyway", r->unparsed_uri); + } + } + + return 1; +} + +int cache_check_freshness(cache_handle_t *h, cache_request_rec *cache, + request_rec *r) +{ + apr_status_t status; + apr_int64_t age, maxage_req, maxage_cresp, maxage, smaxage, maxstale; + apr_int64_t minfresh; + const char *cc_req; + const char *pragma; + const char *agestr = NULL; + apr_time_t age_c = 0; + cache_info *info = &(h->cache_obj->info); + const char *warn_head; + cache_server_conf *conf = + (cache_server_conf *)ap_get_module_config(r->server->module_config, + &cache_module); + + /* + * We now want to check if our cached data is still fresh. This depends + * on a few things, in this order: + * + * - RFC2616 14.9.4 End to end reload, Cache-Control: no-cache. no-cache + * in either the request or the cached response means that we must + * perform the request unconditionally, and ignore cached content. We + * should never reach here, but if we do, mark the content as stale, + * as this is the best we can do. + * + * - RFC2616 14.32 Pragma: no-cache This is treated the same as + * Cache-Control: no-cache. + * + * - RFC2616 14.9.3 Cache-Control: max-stale, must-revalidate, + * proxy-revalidate if the max-stale request header exists, modify the + * stale calculations below so that an object can be at most <max-stale> + * seconds stale before we request a revalidation, _UNLESS_ a + * must-revalidate or proxy-revalidate cached response header exists to + * stop us doing this. + * + * - RFC2616 14.9.3 Cache-Control: s-maxage the origin server specifies the + * maximum age an object can be before it is considered stale. This + * directive has the effect of proxy|must revalidate, which in turn means + * simple ignore any max-stale setting. + * + * - RFC2616 14.9.4 Cache-Control: max-age this header can appear in both + * requests and responses. If both are specified, the smaller of the two + * takes priority. + * + * - RFC2616 14.21 Expires: if this request header exists in the cached + * entity, and it's value is in the past, it has expired. + * + */ + + /* This value comes from the client's initial request. */ + cc_req = apr_table_get(r->headers_in, "Cache-Control"); + pragma = apr_table_get(r->headers_in, "Pragma"); + + ap_cache_control(r, &cache->control_in, cc_req, pragma, r->headers_in); + + if (cache->control_in.no_cache) { + + if (!conf->ignorecachecontrol) { + /* Treat as stale, causing revalidation */ + return 0; + } + + ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r, APLOGNO(00781) + "Incoming request is asking for a uncached version of " + "%s, but we have been configured to ignore it and " + "serve a cached response anyway", + r->unparsed_uri); + } + + /* These come from the cached entity. */ + if (h->cache_obj->info.control.no_cache + || h->cache_obj->info.control.invalidated) { + /* + * The cached entity contained Cache-Control: no-cache, or a + * no-cache with a header present, or a private with a header + * present, or the cached entity has been invalidated in the + * past, so treat as stale causing revalidation. + */ + return 0; + } + + if ((agestr = apr_table_get(h->resp_hdrs, "Age"))) { + char *endp; + apr_off_t offt; + if (!apr_strtoff(&offt, agestr, &endp, 10) + && endp > agestr && !*endp) { + age_c = offt; + } + } + + /* calculate age of object */ + age = ap_cache_current_age(info, age_c, r->request_time); + + /* extract s-maxage */ + smaxage = h->cache_obj->info.control.s_maxage_value; + + /* extract max-age from request */ + maxage_req = -1; + if (!conf->ignorecachecontrol) { + maxage_req = cache->control_in.max_age_value; + } + + /* + * extract max-age from response, if both s-maxage and max-age, s-maxage + * takes priority + */ + if (smaxage != -1) { + maxage_cresp = smaxage; + } + else { + maxage_cresp = h->cache_obj->info.control.max_age_value; + } + + /* + * if both maxage request and response, the smaller one takes priority + */ + if (maxage_req == -1) { + maxage = maxage_cresp; + } + else if (maxage_cresp == -1) { + maxage = maxage_req; + } + else { + maxage = MIN(maxage_req, maxage_cresp); + } + + /* extract max-stale */ + if (cache->control_in.max_stale) { + if (cache->control_in.max_stale_value != -1) { + maxstale = cache->control_in.max_stale_value; + } + else { + /* + * If no value is assigned to max-stale, then the client is willing + * to accept a stale response of any age (RFC2616 14.9.3). We will + * set it to one year in this case as this situation is somewhat + * similar to a "never expires" Expires header (RFC2616 14.21) + * which is set to a date one year from the time the response is + * sent in this case. + */ + maxstale = APR_INT64_C(86400*365); + } + } + else { + maxstale = 0; + } + + /* extract min-fresh */ + if (!conf->ignorecachecontrol && cache->control_in.min_fresh) { + minfresh = cache->control_in.min_fresh_value; + } + else { + minfresh = 0; + } + + /* override maxstale if must-revalidate, proxy-revalidate or s-maxage */ + if (maxstale && (h->cache_obj->info.control.must_revalidate + || h->cache_obj->info.control.proxy_revalidate || smaxage != -1)) { + maxstale = 0; + } + + /* handle expiration */ + if (((maxage != -1) && (age < (maxage + maxstale - minfresh))) || + ((smaxage == -1) && (maxage == -1) && + (info->expire != APR_DATE_BAD) && + (age < (apr_time_sec(info->expire - info->date) + maxstale - minfresh)))) { + + warn_head = apr_table_get(h->resp_hdrs, "Warning"); + + /* it's fresh darlings... */ + /* set age header on response */ + apr_table_set(h->resp_hdrs, "Age", + apr_psprintf(r->pool, "%lu", (unsigned long)age)); + + /* add warning if maxstale overrode freshness calculation */ + if (!(((maxage != -1) && age < maxage) || + (info->expire != APR_DATE_BAD && + (apr_time_sec(info->expire - info->date)) > age))) { + /* make sure we don't stomp on a previous warning */ + if ((warn_head == NULL) || + ((warn_head != NULL) && (ap_strstr_c(warn_head, "110") == NULL))) { + apr_table_mergen(h->resp_hdrs, "Warning", + "110 Response is stale"); + } + } + + /* + * If none of Expires, Cache-Control: max-age, or Cache-Control: + * s-maxage appears in the response, and the response header age + * calculated is more than 24 hours add the warning 113 + */ + if ((maxage_cresp == -1) && (smaxage == -1) && (apr_table_get( + h->resp_hdrs, "Expires") == NULL) && (age > 86400)) { + + /* Make sure we don't stomp on a previous warning, and don't dup + * a 113 marning that is already present. Also, make sure to add + * the new warning to the correct *headers_out location. + */ + if ((warn_head == NULL) || + ((warn_head != NULL) && (ap_strstr_c(warn_head, "113") == NULL))) { + apr_table_mergen(h->resp_hdrs, "Warning", + "113 Heuristic expiration"); + } + } + return 1; /* Cache object is fresh (enough) */ + } + + /* + * At this point we are stale, but: if we are under load, we may let + * a significant number of stale requests through before the first + * stale request successfully revalidates itself, causing a sudden + * unexpected thundering herd which in turn brings angst and drama. + * + * So. + * + * We want the first stale request to go through as normal. But the + * second and subsequent request, we must pretend to be fresh until + * the first request comes back with either new content or confirmation + * that the stale content is still fresh. + * + * To achieve this, we create a very simple file based lock based on + * the key of the cached object. We attempt to open the lock file with + * exclusive write access. If we succeed, woohoo! we're first, and we + * follow the stale path to the backend server. If we fail, oh well, + * we follow the fresh path, and avoid being a thundering herd. + * + * The lock lives only as long as the stale request that went on ahead. + * If the request succeeds, the lock is deleted. If the request fails, + * the lock is deleted, and another request gets to make a new lock + * and try again. + * + * At any time, a request marked "no-cache" will force a refresh, + * ignoring the lock, ensuring an extended lockout is impossible. + * + * A lock that exceeds a maximum age will be deleted, and another + * request gets to make a new lock and try again. + */ + status = cache_try_lock(conf, cache, r); + if (APR_SUCCESS == status) { + /* we obtained a lock, follow the stale path */ + ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00782) + "Cache lock obtained for stale cached URL, " + "revalidating entry: %s", + r->unparsed_uri); + return 0; + } + else if (APR_STATUS_IS_EEXIST(status)) { + /* lock already exists, return stale data anyway, with a warning */ + ap_log_rerror(APLOG_MARK, APLOG_DEBUG, status, r, APLOGNO(00783) + "Cache already locked for stale cached URL, " + "pretend it is fresh: %s", + r->unparsed_uri); + + /* make sure we don't stomp on a previous warning */ + warn_head = apr_table_get(h->resp_hdrs, "Warning"); + if ((warn_head == NULL) || + ((warn_head != NULL) && (ap_strstr_c(warn_head, "110") == NULL))) { + apr_table_mergen(h->resp_hdrs, "Warning", + "110 Response is stale"); + } + + return 1; + } + else { + /* some other error occurred, just treat the object as stale */ + ap_log_rerror(APLOG_MARK, APLOG_DEBUG, status, r, APLOGNO(00784) + "Attempt to obtain a cache lock for stale " + "cached URL failed, revalidating entry anyway: %s", + r->unparsed_uri); + return 0; + } + +} + +/* return each comma separated token, one at a time */ +CACHE_DECLARE(const char *)ap_cache_tokstr(apr_pool_t *p, const char *list, + const char **str) +{ + apr_size_t i; + const char *s; + + s = ap_strchr_c(list, ','); + if (s != NULL) { + i = s - list; + do + s++; + while (apr_isspace(*s)) + ; /* noop */ + } + else + i = strlen(list); + + while (i > 0 && apr_isspace(list[i - 1])) + i--; + + *str = s; + if (i) + return apr_pstrmemdup(p, list, i); + else + return NULL; +} + +/* + * Converts apr_time_t expressed as hex digits to + * a true apr_time_t. + */ +CACHE_DECLARE(apr_time_t) ap_cache_hex2usec(const char *x) +{ + int i, ch; + apr_time_t j; + for (i = 0, j = 0; i < sizeof(j) * 2; i++) { + ch = x[i]; + j <<= 4; + if (apr_isdigit(ch)) + j |= ch - '0'; + else if (apr_isupper(ch)) + j |= ch - ('A' - 10); + else + j |= ch - ('a' - 10); + } + return j; +} + +/* + * Converts apr_time_t to apr_time_t expressed as hex digits. + */ +CACHE_DECLARE(void) ap_cache_usec2hex(apr_time_t j, char *y) +{ + int i, ch; + + for (i = (sizeof(j) * 2)-1; i >= 0; i--) { + ch = (int)(j & 0xF); + j >>= 4; + if (ch >= 10) + y[i] = ch + ('A' - 10); + else + y[i] = ch + '0'; + } + y[sizeof(j) * 2] = '\0'; +} + +static void cache_hash(const char *it, char *val, int ndepth, int nlength) +{ + apr_md5_ctx_t context; + unsigned char digest[16]; + char tmp[22]; + int i, k, d; + unsigned int x; + static const char enc_table[64] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_@"; + + apr_md5_init(&context); + apr_md5_update(&context, (const unsigned char *) it, strlen(it)); + apr_md5_final(digest, &context); + + /* encode 128 bits as 22 characters, using a modified uuencoding + * the encoding is 3 bytes -> 4 characters* i.e. 128 bits is + * 5 x 3 bytes + 1 byte -> 5 * 4 characters + 2 characters + */ + for (i = 0, k = 0; i < 15; i += 3) { + x = (digest[i] << 16) | (digest[i + 1] << 8) | digest[i + 2]; + tmp[k++] = enc_table[x >> 18]; + tmp[k++] = enc_table[(x >> 12) & 0x3f]; + tmp[k++] = enc_table[(x >> 6) & 0x3f]; + tmp[k++] = enc_table[x & 0x3f]; + } + + /* one byte left */ + x = digest[15]; + tmp[k++] = enc_table[x >> 2]; /* use up 6 bits */ + tmp[k++] = enc_table[(x << 4) & 0x3f]; + + /* now split into directory levels */ + for (i = k = d = 0; d < ndepth; ++d) { + memcpy(&val[i], &tmp[k], nlength); + k += nlength; + val[i + nlength] = '/'; + i += nlength + 1; + } + memcpy(&val[i], &tmp[k], 22 - k); + val[i + 22 - k] = '\0'; +} + +CACHE_DECLARE(char *)ap_cache_generate_name(apr_pool_t *p, int dirlevels, + int dirlength, const char *name) +{ + char hashfile[66]; + cache_hash(name, hashfile, dirlevels, dirlength); + return apr_pstrdup(p, hashfile); +} + +/** + * String tokenizer that ignores separator characters within quoted strings + * and escaped characters, as per RFC2616 section 2.2. + */ +char *cache_strqtok(char *str, const char *sep, char **last) +{ + char *token; + int quoted = 0; + + if (!str) { /* subsequent call */ + str = *last; /* start where we left off */ + } + + if (!str) { /* no more tokens */ + return NULL; + } + + /* skip characters in sep (will terminate at '\0') */ + while (*str && ap_strchr_c(sep, *str)) { + ++str; + } + + if (!*str) { /* no more tokens */ + return NULL; + } + + token = str; + + /* skip valid token characters to terminate token and + * prepare for the next call (will terminate at '\0) + * on the way, ignore all quoted strings, and within + * quoted strings, escaped characters. + */ + *last = token; + while (**last) { + if (!quoted) { + if (**last == '\"' && !ap_strchr_c(sep, '\"')) { + quoted = 1; + ++*last; + } + else if (!ap_strchr_c(sep, **last)) { + ++*last; + } + else { + break; + } + } + else { + if (**last == '\"') { + quoted = 0; + ++*last; + } + else if (**last == '\\') { + ++*last; + if (**last) { + ++*last; + } + } + else { + ++*last; + } + } + } + + if (**last) { + **last = '\0'; + ++*last; + } + + return token; +} + +/** + * Parse the Cache-Control and Pragma headers in one go, marking + * which tokens appear within the header. Populate the structure + * passed in. + */ +int ap_cache_control(request_rec *r, cache_control_t *cc, + const char *cc_header, const char *pragma_header, apr_table_t *headers) +{ + char *last; + + if (cc->parsed) { + return cc->cache_control || cc->pragma; + } + + cc->parsed = 1; + cc->max_age_value = -1; + cc->max_stale_value = -1; + cc->min_fresh_value = -1; + cc->s_maxage_value = -1; + + if (pragma_header) { + char *header = apr_pstrdup(r->pool, pragma_header); + const char *token = cache_strqtok(header, CACHE_SEPARATOR, &last); + while (token) { + if (!ap_cstr_casecmp(token, "no-cache")) { + cc->no_cache = 1; + } + token = cache_strqtok(NULL, CACHE_SEPARATOR, &last); + } + cc->pragma = 1; + } + + if (cc_header) { + char *endp; + apr_off_t offt; + char *header = apr_pstrdup(r->pool, cc_header); + const char *token = cache_strqtok(header, CACHE_SEPARATOR, &last); + while (token) { + switch (token[0]) { + case 'n': + case 'N': { + if (!ap_cstr_casecmpn(token, "no-cache", 8)) { + if (token[8] == '=') { + cc->no_cache_header = 1; + } + else if (!token[8]) { + cc->no_cache = 1; + } + } + else if (!ap_cstr_casecmp(token, "no-store")) { + cc->no_store = 1; + } + else if (!ap_cstr_casecmp(token, "no-transform")) { + cc->no_transform = 1; + } + break; + } + case 'm': + case 'M': { + if (!ap_cstr_casecmpn(token, "max-age", 7)) { + if (token[7] == '=' + && !apr_strtoff(&offt, token + 8, &endp, 10) + && endp > token + 8 && !*endp) { + cc->max_age = 1; + cc->max_age_value = offt; + } + } + else if (!ap_cstr_casecmp(token, "must-revalidate")) { + cc->must_revalidate = 1; + } + else if (!ap_cstr_casecmpn(token, "max-stale", 9)) { + if (token[9] == '=' + && !apr_strtoff(&offt, token + 10, &endp, 10) + && endp > token + 10 && !*endp) { + cc->max_stale = 1; + cc->max_stale_value = offt; + } + else if (!token[9]) { + cc->max_stale = 1; + cc->max_stale_value = -1; + } + } + else if (!ap_cstr_casecmpn(token, "min-fresh", 9)) { + if (token[9] == '=' + && !apr_strtoff(&offt, token + 10, &endp, 10) + && endp > token + 10 && !*endp) { + cc->min_fresh = 1; + cc->min_fresh_value = offt; + } + } + break; + } + case 'o': + case 'O': { + if (!ap_cstr_casecmp(token, "only-if-cached")) { + cc->only_if_cached = 1; + } + break; + } + case 'p': + case 'P': { + if (!ap_cstr_casecmp(token, "public")) { + cc->public = 1; + } + else if (!ap_cstr_casecmpn(token, "private", 7)) { + if (token[7] == '=') { + cc->private_header = 1; + } + else if (!token[7]) { + cc->private = 1; + } + } + else if (!ap_cstr_casecmp(token, "proxy-revalidate")) { + cc->proxy_revalidate = 1; + } + break; + } + case 's': + case 'S': { + if (!ap_cstr_casecmpn(token, "s-maxage", 8)) { + if (token[8] == '=' + && !apr_strtoff(&offt, token + 9, &endp, 10) + && endp > token + 9 && !*endp) { + cc->s_maxage = 1; + cc->s_maxage_value = offt; + } + } + break; + } + } + token = cache_strqtok(NULL, CACHE_SEPARATOR, &last); + } + cc->cache_control = 1; + } + + return (cc_header != NULL || pragma_header != NULL); +} + +/** + * Parse the Cache-Control, identifying and removing headers that + * exist as tokens after the no-cache and private tokens. + */ +static int cache_control_remove(request_rec *r, const char *cc_header, + apr_table_t *headers) +{ + char *last, *slast; + int found = 0; + + if (cc_header) { + char *header = apr_pstrdup(r->pool, cc_header); + char *token = cache_strqtok(header, CACHE_SEPARATOR, &last); + while (token) { + switch (token[0]) { + case 'n': + case 'N': { + if (!ap_cstr_casecmpn(token, "no-cache", 8)) { + if (token[8] == '=') { + const char *header = cache_strqtok(token + 9, + CACHE_SEPARATOR "\"", &slast); + while (header) { + apr_table_unset(headers, header); + header = cache_strqtok(NULL, CACHE_SEPARATOR "\"", + &slast); + } + found = 1; + } + } + break; + } + case 'p': + case 'P': { + if (!ap_cstr_casecmpn(token, "private", 7)) { + if (token[7] == '=') { + const char *header = cache_strqtok(token + 8, + CACHE_SEPARATOR "\"", &slast); + while (header) { + apr_table_unset(headers, header); + header = cache_strqtok(NULL, CACHE_SEPARATOR "\"", + &slast); + } + found = 1; + } + } + break; + } + } + token = cache_strqtok(NULL, CACHE_SEPARATOR, &last); + } + } + + return found; +} + +/* + * Create a new table consisting of those elements from an + * headers table that are allowed to be stored in a cache. + */ +CACHE_DECLARE(apr_table_t *)ap_cache_cacheable_headers(apr_pool_t *pool, + apr_table_t *t, + server_rec *s) +{ + cache_server_conf *conf; + char **header; + int i; + apr_table_t *headers_out; + + /* Short circuit the common case that there are not + * (yet) any headers populated. + */ + if (t == NULL) { + return apr_table_make(pool, 10); + }; + + /* Make a copy of the headers, and remove from + * the copy any hop-by-hop headers, as defined in Section + * 13.5.1 of RFC 2616 + */ + headers_out = apr_table_copy(pool, t); + + apr_table_unset(headers_out, "Connection"); + apr_table_unset(headers_out, "Keep-Alive"); + apr_table_unset(headers_out, "Proxy-Authenticate"); + apr_table_unset(headers_out, "Proxy-Authorization"); + apr_table_unset(headers_out, "TE"); + apr_table_unset(headers_out, "Trailers"); + apr_table_unset(headers_out, "Transfer-Encoding"); + apr_table_unset(headers_out, "Upgrade"); + + conf = (cache_server_conf *)ap_get_module_config(s->module_config, + &cache_module); + + /* Remove the user defined headers set with CacheIgnoreHeaders. + * This may break RFC 2616 compliance on behalf of the administrator. + */ + header = (char **)conf->ignore_headers->elts; + for (i = 0; i < conf->ignore_headers->nelts; i++) { + apr_table_unset(headers_out, header[i]); + } + return headers_out; +} + +/* + * Create a new table consisting of those elements from an input + * headers table that are allowed to be stored in a cache. + */ +CACHE_DECLARE(apr_table_t *)ap_cache_cacheable_headers_in(request_rec *r) +{ + return ap_cache_cacheable_headers(r->pool, r->headers_in, r->server); +} + +/* + * Create a new table consisting of those elements from an output + * headers table that are allowed to be stored in a cache; + * ensure there is a content type and capture any errors. + */ +CACHE_DECLARE(apr_table_t *)ap_cache_cacheable_headers_out(request_rec *r) +{ + apr_table_t *headers_out; + + headers_out = ap_cache_cacheable_headers(r->pool, + cache_merge_headers_out(r), + r->server); + + cache_control_remove(r, + cache_table_getm(r->pool, headers_out, "Cache-Control"), + headers_out); + + return headers_out; +} + +apr_table_t *cache_merge_headers_out(request_rec *r) +{ + apr_table_t *headers_out; + + headers_out = apr_table_overlay(r->pool, r->headers_out, + r->err_headers_out); + + if (r->content_type + && !apr_table_get(headers_out, "Content-Type")) { + const char *ctype = ap_make_content_type(r, r->content_type); + if (ctype) { + apr_table_setn(headers_out, "Content-Type", ctype); + } + } + + if (r->content_encoding + && !apr_table_get(headers_out, "Content-Encoding")) { + apr_table_setn(headers_out, "Content-Encoding", + r->content_encoding); + } + + return headers_out; +} + +typedef struct +{ + apr_pool_t *p; + const char *first; + apr_array_header_t *merged; +} cache_table_getm_t; + +static int cache_table_getm_do(void *v, const char *key, const char *val) +{ + cache_table_getm_t *state = (cache_table_getm_t *) v; + + if (!state->first) { + /** + * The most common case is a single header, and this is covered by + * a fast path that doesn't allocate any memory. On the second and + * subsequent header, an array is created and the array concatenated + * together to form the final value. + */ + state->first = val; + } + else { + const char **elt; + if (!state->merged) { + state->merged = apr_array_make(state->p, 10, sizeof(const char *)); + elt = apr_array_push(state->merged); + *elt = state->first; + } + elt = apr_array_push(state->merged); + *elt = val; + } + return 1; +} + +const char *cache_table_getm(apr_pool_t *p, const apr_table_t *t, + const char *key) +{ + cache_table_getm_t state; + + state.p = p; + state.first = NULL; + state.merged = NULL; + + apr_table_do(cache_table_getm_do, &state, t, key, NULL); + + if (!state.first) { + return NULL; + } + else if (!state.merged) { + return state.first; + } + else { + return apr_array_pstrcat(p, state.merged, ','); + } +} |