Imported Upstream version 2.3.16-beta

1 files changed, 1224 insertions, 303 deletions

diff --git a/modules/cache/mod_cache.c b/modules/cache/mod_cache.c
index 8aeb3f73..17fc9d3f 100644
--- a/modules/cache/mod_cache.c
+++ b/modules/cache/mod_cache.c
@@ -14,10 +14,11 @@
  * limitations under the License.
  */
 
-#define CORE_PRIVATE
-
 #include "mod_cache.h"
 
+#include "cache_storage.h"
+#include "cache_util.h"
+
 module AP_MODULE_DECLARE_DATA cache_module;
 APR_OPTIONAL_FN_TYPE(ap_cache_generate_key) *cache_generate_key;
 
@@ -27,6 +28,7 @@ APR_OPTIONAL_FN_TYPE(ap_cache_generate_key) *cache_generate_key;
 /* Handles for cache filters, resolved at startup to eliminate
  * a name-to-function mapping on each request
  */
+static ap_filter_rec_t *cache_filter_handle;
 static ap_filter_rec_t *cache_save_filter_handle;
 static ap_filter_rec_t *cache_save_subreq_filter_handle;
 static ap_filter_rec_t *cache_out_filter_handle;
@@ -46,18 +48,32 @@ static ap_filter_rec_t *cache_remove_url_filter_handle;
  *     add CACHE_SAVE filter
  *   If No:
  *     oh well.
+ *
+ * By default, the cache handler runs in the quick handler, bypassing
+ * virtually all server processing and offering the cache its optimal
+ * performance. In this mode, the cache bolts onto the front of the
+ * server, and behaves as a discrete RFC2616 caching proxy
+ * implementation.
+ *
+ * Under certain circumstances, an admin might want to run the cache as
+ * a normal handler instead of a quick handler, allowing the cache to
+ * run after the authorisation hooks, or by allowing fine control over
+ * the placement of the cache in the filter chain. This option comes at
+ * a performance penalty, and should only be used to achieve specific
+ * caching goals where the admin understands what they are doing.
  */
 
-static int cache_url_handler(request_rec *r, int lookup)
+static int cache_quick_handler(request_rec *r, int lookup)
 {
     apr_status_t rv;
     const char *auth;
     cache_provider_list *providers;
     cache_request_rec *cache;
-    cache_server_conf *conf;
     apr_bucket_brigade *out;
+    apr_bucket *e;
     ap_filter_t *next;
     ap_filter_rec_t *cache_out_handle;
+    cache_server_conf *conf;
 
     /* Delay initialization until we know we are handling a GET */
     if (r->method_number != M_GET) {
@@ -67,20 +83,22 @@ static int cache_url_handler(request_rec *r, int lookup)
     conf = (cache_server_conf *) ap_get_module_config(r->server->module_config,
                                                       &cache_module);
 
+    /* only run if the quick handler is enabled */
+    if (!conf->quick) {
+        return DECLINED;
+    }
+
     /*
      * Which cache module (if any) should handle this request?
      */
-    if (!(providers = ap_cache_get_providers(r, conf, r->parsed_uri))) {
+    if (!(providers = cache_get_providers(r, conf, r->parsed_uri))) {
         return DECLINED;
     }
 
     /* make space for the per request config */
-    cache = (cache_request_rec *) ap_get_module_config(r->request_config,
-                                                       &cache_module);
-    if (!cache) {
-        cache = apr_pcalloc(r->pool, sizeof(cache_request_rec));
-        ap_set_module_config(r->request_config, &cache_module, cache);
-    }
+    cache = apr_pcalloc(r->pool, sizeof(cache_request_rec));
+    cache->size = -1;
+    cache->out = apr_brigade_create(r->pool, r->connection->bucket_alloc);
 
     /* save away the possible providers */
     cache->providers = providers;
@@ -109,7 +127,7 @@ static int cache_url_handler(request_rec *r, int lookup)
      *   add cache_out filter
      *   return OK
      */
-    rv = cache_select(r);
+    rv = cache_select(cache, r);
     if (rv != OK) {
         if (rv == DECLINED) {
             if (!lookup) {
@@ -121,7 +139,7 @@ static int cache_url_handler(request_rec *r, int lookup)
                  * backend without any attempt to cache. this stops
                  * duplicated simultaneous attempts to cache an entity.
                  */
-                rv = ap_cache_try_lock(conf, r, NULL);
+                rv = cache_try_lock(conf, cache, r);
                 if (APR_SUCCESS == rv) {
 
                     /*
@@ -130,29 +148,32 @@ static int cache_url_handler(request_rec *r, int lookup)
                      * or not.
                      */
                     if (r->main) {
-                        ap_log_error(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
-                                r->server,
-                                "Adding CACHE_SAVE_SUBREQ filter for %s",
+                        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
+                                r, APLOGNO(00749) "Adding CACHE_SAVE_SUBREQ filter for %s",
                                 r->uri);
-                        ap_add_output_filter_handle(cache_save_subreq_filter_handle,
-                                NULL, r, r->connection);
+                        cache->save_filter = ap_add_output_filter_handle(
+                                cache_save_subreq_filter_handle, cache, r,
+                                r->connection);
                     }
                     else {
-                        ap_log_error(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
-                                r->server, "Adding CACHE_SAVE filter for %s",
+                        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
+                                r, APLOGNO(00750) "Adding CACHE_SAVE filter for %s",
                                 r->uri);
-                        ap_add_output_filter_handle(cache_save_filter_handle,
-                                NULL, r, r->connection);
+                        cache->save_filter = ap_add_output_filter_handle(
+                                cache_save_filter_handle, cache, r,
+                                r->connection);
                     }
 
-                    ap_log_error(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r->server,
+                    apr_pool_userdata_setn(cache, CACHE_CTX_KEY, NULL, r->pool);
+
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r, APLOGNO(00751)
                             "Adding CACHE_REMOVE_URL filter for %s",
                             r->uri);
 
                     /* Add cache_remove_url filter to this request to remove a
                      * stale cache entry if needed. Also put the current cache
                      * request rec in the filter context, as the request that
-                     * is available later during running the filter maybe
+                     * is available later during running the filter may be
                      * different due to an internal redirect.
                      */
                     cache->remove_url_filter =
@@ -160,44 +181,40 @@ static int cache_url_handler(request_rec *r, int lookup)
                                 cache, r, r->connection);
                 }
                 else {
-                    ap_log_error(APLOG_MARK, APLOG_DEBUG, rv,
-                                 r->server, "Cache locked for url, not caching "
-                                 "response: %s", r->uri);
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv,
+                            r, APLOGNO(00752) "Cache locked for url, not caching "
+                            "response: %s", r->uri);
                 }
             }
             else {
                 if (cache->stale_headers) {
-                    ap_log_error(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
-                                 r->server, "Restoring request headers for %s",
-                                 r->uri);
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
+                            r, APLOGNO(00753) "Restoring request headers for %s",
+                            r->uri);
 
                     r->headers_in = cache->stale_headers;
                 }
-
-                /* Delete our per-request configuration. */
-                ap_set_module_config(r->request_config, &cache_module, NULL);
             }
         }
         else {
             /* error */
-            ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
-                         "cache: error returned while checking for cached "
-                         "file by '%s' cache", cache->provider_name);
+            return rv;
         }
         return DECLINED;
     }
 
+    /* we've got a cache hit! tell everyone who cares */
+    cache_run_cache_status(cache->handle, r, r->headers_out, AP_CACHE_HIT,
+            "cache hit");
+
     /* if we are a lookup, we are exiting soon one way or another; Restore
      * the headers. */
     if (lookup) {
         if (cache->stale_headers) {
-            ap_log_error(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r->server,
-                         "Restoring request headers.");
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r, APLOGNO(00754)
+                    "Restoring request headers.");
             r->headers_in = cache->stale_headers;
         }
-
-        /* Delete our per-request configuration. */
-        ap_set_module_config(r->request_config, &cache_module, NULL);
     }
 
     rv = ap_meets_conditions(r);
@@ -236,7 +253,7 @@ static int cache_url_handler(request_rec *r, int lookup)
     else {
         cache_out_handle = cache_out_filter_handle;
     }
-    ap_add_output_filter_handle(cache_out_handle, NULL, r, r->connection);
+    ap_add_output_filter_handle(cache_out_handle, cache, r, r->connection);
 
     /*
      * Remove all filters that are before the cache_out filter. This ensures
@@ -258,18 +275,269 @@ static int cache_url_handler(request_rec *r, int lookup)
 
     /* kick off the filter stack */
     out = apr_brigade_create(r->pool, r->connection->bucket_alloc);
-    rv = ap_pass_brigade(r->output_filters, out);
-    if (rv != APR_SUCCESS) {
-        if (rv != AP_FILTER_ERROR) {
-            ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
-                         "cache: error returned while trying to return %s "
-                         "cached data",
-                         cache->provider_name);
+    e = apr_bucket_eos_create(out->bucket_alloc);
+    APR_BRIGADE_INSERT_TAIL(out, e);
+
+    return ap_pass_brigade_fchk(r, out,
+                                "cache_quick_handler(%s): ap_pass_brigade returned",
+                                cache->provider_name);
+}
+
+/**
+ * If the two filter handles are present within the filter chain, replace
+ * the last instance of the first filter with the last instance of the
+ * second filter, and return true. If the second filter is not present at
+ * all, the first filter is removed, and false is returned. If neither
+ * filter is present, false is returned and this function does nothing.
+ * If a stop filter is specified, processing will stop once this filter is
+ * reached.
+ */
+static int cache_replace_filter(ap_filter_t *next, ap_filter_rec_t *from,
+        ap_filter_rec_t *to, ap_filter_rec_t *stop) {
+    ap_filter_t *ffrom = NULL, *fto = NULL;
+    while (next && next->frec != stop) {
+        if (next->frec == from) {
+            ffrom = next;
+        }
+        if (next->frec == to) {
+            fto = next;
+        }
+        next = next->next;
+    }
+    if (ffrom && fto) {
+        ffrom->frec = fto->frec;
+        ffrom->ctx = fto->ctx;
+        ap_remove_output_filter(fto);
+        return 1;
+    }
+    if (ffrom) {
+        ap_remove_output_filter(ffrom);
+    }
+    return 0;
+}
+
+/**
+ * Find the given filter, and return it if found, or NULL otherwise.
+ */
+static ap_filter_t *cache_get_filter(ap_filter_t *next, ap_filter_rec_t *rec) {
+    while (next) {
+        if (next->frec == rec && next->ctx) {
+            break;
         }
+        next = next->next;
+    }
+    return next;
+}
+
+/**
+ * The cache handler is functionally similar to the cache_quick_hander,
+ * however a number of steps that are required by the quick handler are
+ * not required here, as the normal httpd processing has already handled
+ * these steps.
+ */
+static int cache_handler(request_rec *r)
+{
+    apr_status_t rv;
+    cache_provider_list *providers;
+    cache_request_rec *cache;
+    apr_bucket_brigade *out;
+    apr_bucket *e;
+    ap_filter_t *next;
+    ap_filter_rec_t *cache_out_handle;
+    ap_filter_rec_t *cache_save_handle;
+    cache_server_conf *conf;
+
+    /* Delay initialization until we know we are handling a GET */
+    if (r->method_number != M_GET) {
+        return DECLINED;
+    }
+
+    conf = (cache_server_conf *) ap_get_module_config(r->server->module_config,
+                                                      &cache_module);
+
+    /* only run if the quick handler is disabled */
+    if (conf->quick) {
+        return DECLINED;
+    }
+
+    /*
+     * Which cache module (if any) should handle this request?
+     */
+    if (!(providers = cache_get_providers(r, conf, r->parsed_uri))) {
+        return DECLINED;
+    }
+
+    /* make space for the per request config */
+    cache = apr_pcalloc(r->pool, sizeof(cache_request_rec));
+    cache->size = -1;
+    cache->out = apr_brigade_create(r->pool, r->connection->bucket_alloc);
+
+    /* save away the possible providers */
+    cache->providers = providers;
+
+    /*
+     * Try to serve this request from the cache.
+     *
+     * If no existing cache file (DECLINED)
+     *   add cache_save filter
+     * If cached file (OK)
+     *   clear filter stack
+     *   add cache_out filter
+     *   return OK
+     */
+    rv = cache_select(cache, r);
+    if (rv != OK) {
+        if (rv == DECLINED) {
+
+            /* try to obtain a cache lock at this point. if we succeed,
+             * we are the first to try and cache this url. if we fail,
+             * it means someone else is already trying to cache this
+             * url, and we should just let the request through to the
+             * backend without any attempt to cache. this stops
+             * duplicated simultaneous attempts to cache an entity.
+             */
+            rv = cache_try_lock(conf, cache, r);
+            if (APR_SUCCESS == rv) {
+
+                /*
+                 * Add cache_save filter to cache this request. Choose
+                 * the correct filter by checking if we are a subrequest
+                 * or not.
+                 */
+                if (r->main) {
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
+                            r, APLOGNO(00756) "Adding CACHE_SAVE_SUBREQ filter for %s",
+                            r->uri);
+                    cache_save_handle = cache_save_subreq_filter_handle;
+                }
+                else {
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
+                            r, APLOGNO(00757) "Adding CACHE_SAVE filter for %s",
+                            r->uri);
+                    cache_save_handle = cache_save_filter_handle;
+                }
+                ap_add_output_filter_handle(cache_save_handle, cache, r,
+                        r->connection);
+
+                /*
+                 * Did the user indicate the precise location of the
+                 * CACHE_SAVE filter by inserting the CACHE filter as a
+                 * marker?
+                 *
+                 * If so, we get cunning and replace CACHE with the
+                 * CACHE_SAVE filter. This has the effect of inserting
+                 * the CACHE_SAVE filter at the precise location where
+                 * the admin wants to cache the content. All filters that
+                 * lie before and after the original location of the CACHE
+                 * filter will remain in place.
+                 */
+                if (cache_replace_filter(r->output_filters,
+                        cache_filter_handle, cache_save_handle,
+                        ap_get_input_filter_handle("SUBREQ_CORE"))) {
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
+                            r, APLOGNO(00758) "Replacing CACHE with CACHE_SAVE "
+                            "filter for %s", r->uri);
+                }
+
+                /* save away the save filter stack */
+                cache->save_filter = cache_get_filter(r->output_filters,
+                        cache_save_filter_handle);
+
+                apr_pool_userdata_setn(cache, CACHE_CTX_KEY, NULL, r->pool);
+
+                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r, APLOGNO(00759)
+                        "Adding CACHE_REMOVE_URL filter for %s",
+                        r->uri);
+
+                /* Add cache_remove_url filter to this request to remove a
+                 * stale cache entry if needed. Also put the current cache
+                 * request rec in the filter context, as the request that
+                 * is available later during running the filter may be
+                 * different due to an internal redirect.
+                 */
+                cache->remove_url_filter =
+                    ap_add_output_filter_handle(cache_remove_url_filter_handle,
+                            cache, r, r->connection);
+
+            }
+            else {
+                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv,
+                        r, APLOGNO(00760) "Cache locked for url, not caching "
+                        "response: %s", r->uri);
+            }
+        }
+        else {
+            /* error */
+            return rv;
+        }
+        return DECLINED;
+    }
+
+    /* we've got a cache hit! tell everyone who cares */
+    cache_run_cache_status(cache->handle, r, r->headers_out, AP_CACHE_HIT,
+            "cache hit");
+
+    rv = ap_meets_conditions(r);
+    if (rv != OK) {
         return rv;
     }
 
-    return OK;
+    /* Serve up the content */
+
+    /*
+     * Add cache_out filter to serve this request. Choose
+     * the correct filter by checking if we are a subrequest
+     * or not.
+     */
+    if (r->main) {
+        cache_out_handle = cache_out_subreq_filter_handle;
+    }
+    else {
+        cache_out_handle = cache_out_filter_handle;
+    }
+    ap_add_output_filter_handle(cache_out_handle, cache, r, r->connection);
+
+    /*
+     * Did the user indicate the precise location of the CACHE_OUT filter by
+     * inserting the CACHE filter as a marker?
+     *
+     * If so, we get cunning and replace CACHE with the CACHE_OUT filters.
+     * This has the effect of inserting the CACHE_OUT filter at the precise
+     * location where the admin wants to cache the content. All filters that
+     * lie *after* the original location of the CACHE filter will remain in
+     * place.
+     */
+    if (cache_replace_filter(r->output_filters, cache_filter_handle,
+            cache_out_handle, ap_get_input_filter_handle("SUBREQ_CORE"))) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS,
+                r, APLOGNO(00761) "Replacing CACHE with CACHE_OUT filter for %s",
+                r->uri);
+    }
+
+    /*
+     * Remove all filters that are before the cache_out filter. This ensures
+     * that we kick off the filter stack with our cache_out filter being the
+     * first in the chain. This make sense because we want to restore things
+     * in the same manner as we saved them.
+     * There may be filters before our cache_out filter, because
+     *
+     * 1. We call ap_set_content_type during cache_select. This causes
+     *    Content-Type specific filters to be added.
+     * 2. We call the insert_filter hook. This causes filters e.g. like
+     *    the ones set with SetOutputFilter to be added.
+     */
+    next = r->output_filters;
+    while (next && (next->frec != cache_out_handle)) {
+        ap_remove_output_filter(next);
+        next = next->next;
+    }
+
+    /* kick off the filter stack */
+    out = apr_brigade_create(r->pool, r->connection->bucket_alloc);
+    e = apr_bucket_eos_create(out->bucket_alloc);
+    APR_BRIGADE_INSERT_TAIL(out, e);
+    return ap_pass_brigade_fchk(r, out, "cache(%s): ap_pass_brigade returned",
+                                cache->provider_name);
 }
 
 /*
@@ -278,42 +546,134 @@ static int cache_url_handler(request_rec *r, int lookup)
  *
  * Deliver cached content (headers and body) up the stack.
  */
-static int cache_out_filter(ap_filter_t *f, apr_bucket_brigade *bb)
+static int cache_out_filter(ap_filter_t *f, apr_bucket_brigade *in)
 {
     request_rec *r = f->r;
-    cache_request_rec *cache;
-
-    cache = (cache_request_rec *) ap_get_module_config(r->request_config,
-                                                       &cache_module);
+    apr_bucket *e;
+    cache_request_rec *cache = (cache_request_rec *)f->ctx;
 
     if (!cache) {
         /* user likely configured CACHE_OUT manually; they should use mod_cache
          * configuration to do that */
-        ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
-                     "CACHE_OUT enabled unexpectedly");
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00762)
+                "CACHE/CACHE_OUT filter enabled while caching is disabled, ignoring");
         ap_remove_output_filter(f);
-        return ap_pass_brigade(f->next, bb);
+        return ap_pass_brigade(f->next, in);
     }
 
-    ap_log_error(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r->server,
-                 "cache: running CACHE_OUT filter");
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r, APLOGNO(00763)
+            "cache: running CACHE_OUT filter");
+
+    /* clean out any previous response up to EOS, if any */
+    for (e = APR_BRIGADE_FIRST(in);
+         e != APR_BRIGADE_SENTINEL(in);
+         e = APR_BUCKET_NEXT(e))
+    {
+        if (APR_BUCKET_IS_EOS(e)) {
+            apr_bucket_brigade *bb = apr_brigade_create(r->pool,
+                    r->connection->bucket_alloc);
 
-    /* restore status of cached response */
-    /* XXX: This exposes a bug in mem_cache, since it does not
-     * restore the status into it's handle. */
-    r->status = cache->handle->cache_obj->info.status;
+            /* restore status of cached response */
+            r->status = cache->handle->cache_obj->info.status;
 
-    /* recall_headers() was called in cache_select() */
-    cache->provider->recall_body(cache->handle, r->pool, bb);
+            /* recall_headers() was called in cache_select() */
+            cache->provider->recall_body(cache->handle, r->pool, bb);
+            APR_BRIGADE_PREPEND(in, bb);
 
-    /* This filter is done once it has served up its content */
-    ap_remove_output_filter(f);
+            /* This filter is done once it has served up its content */
+            ap_remove_output_filter(f);
+
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r, APLOGNO(00764)
+                    "cache: serving %s", r->uri);
+            return ap_pass_brigade(f->next, in);
+
+        }
+        apr_bucket_delete(e);
+    }
 
-    ap_log_error(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r->server,
-                 "cache: serving %s", r->uri);
-    return ap_pass_brigade(f->next, bb);
+    return APR_SUCCESS;
 }
 
+/*
+ * Having jumped through all the hoops and decided to cache the
+ * response, call store_body() for each brigade, handling the
+ * case where the provider can't swallow the full brigade. In this
+ * case, we write the brigade we were passed out downstream, and
+ * loop around to try and cache some more until the in brigade is
+ * completely empty. As soon as the out brigade contains eos, call
+ * commit_entity() to finalise the cached element.
+ */
+static int cache_save_store(ap_filter_t *f, apr_bucket_brigade *in,
+        cache_server_conf *conf, cache_request_rec *cache)
+{
+    int rv = APR_SUCCESS;
+    apr_bucket *e;
+
+    /* pass the brigade in into the cache provider, which is then
+     * expected to move cached buckets to the out brigade, for us
+     * to pass up the filter stack. repeat until in is empty, or
+     * we fail.
+     */
+    while (APR_SUCCESS == rv && !APR_BRIGADE_EMPTY(in)) {
+
+        rv = cache->provider->store_body(cache->handle, f->r, in, cache->out);
+        if (rv != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv, f->r, APLOGNO(00765)
+                    "cache: Cache provider's store_body failed!");
+            ap_remove_output_filter(f);
+
+            /* give someone else the chance to cache the file */
+            cache_remove_lock(conf, cache, f->r, NULL);
+
+            /* give up trying to cache, just step out the way */
+            APR_BRIGADE_PREPEND(in, cache->out);
+            return ap_pass_brigade(f->next, in);
+
+        }
+
+        /* does the out brigade contain eos? if so, we're done, commit! */
+        for (e = APR_BRIGADE_FIRST(cache->out);
+             e != APR_BRIGADE_SENTINEL(cache->out);
+             e = APR_BUCKET_NEXT(e))
+        {
+            if (APR_BUCKET_IS_EOS(e)) {
+                rv = cache->provider->commit_entity(cache->handle, f->r);
+                break;
+            }
+        }
+
+        /* conditionally remove the lock as soon as we see the eos bucket */
+        cache_remove_lock(conf, cache, f->r, cache->out);
+
+        if (APR_BRIGADE_EMPTY(cache->out)) {
+            if (APR_BRIGADE_EMPTY(in)) {
+                /* cache provider wants more data before passing the brigade
+                 * upstream, oblige the provider by leaving to fetch more.
+                 */
+                break;
+            }
+            else {
+                /* oops, no data out, but not all data read in either, be
+                 * safe and stand down to prevent a spin.
+                 */
+                ap_log_rerror(APLOG_MARK, APLOG_WARNING, rv, f->r, APLOGNO(00766)
+                        "cache: Cache provider's store_body returned an "
+                        "empty brigade, but didn't consume all of the"
+                        "input brigade, standing down to prevent a spin");
+                ap_remove_output_filter(f);
+
+                /* give someone else the chance to cache the file */
+                cache_remove_lock(conf, cache, f->r, NULL);
+
+                return ap_pass_brigade(f->next, in);
+            }
+        }
+
+        rv = ap_pass_brigade(f->next, cache->out);
+    }
+
+    return rv;
+}
 
 /*
  * CACHE_SAVE filter
@@ -339,29 +699,32 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
 {
     int rv = !OK;
     request_rec *r = f->r;
-    cache_request_rec *cache;
+    cache_request_rec *cache = (cache_request_rec *)f->ctx;
     cache_server_conf *conf;
-    const char *cc_out, *cl;
+    cache_dir_conf *dconf;
+    cache_control_t control;
+    const char *cc_out, *cl, *pragma;
     const char *exps, *lastmods, *dates, *etag;
     apr_time_t exp, date, lastmod, now;
-    apr_off_t size;
+    apr_off_t size = -1;
     cache_info *info = NULL;
     char *reason;
     apr_pool_t *p;
     apr_bucket *e;
+    apr_table_t *headers;
 
     conf = (cache_server_conf *) ap_get_module_config(r->server->module_config,
                                                       &cache_module);
 
     /* Setup cache_request_rec */
-    cache = (cache_request_rec *) ap_get_module_config(r->request_config,
-                                                       &cache_module);
     if (!cache) {
         /* user likely configured CACHE_SAVE manually; they should really use
          * mod_cache configuration to do that
          */
-        cache = apr_pcalloc(r->pool, sizeof(cache_request_rec));
-        ap_set_module_config(r->request_config, &cache_module, cache);
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00767)
+                "CACHE/CACHE_SAVE filter enabled while caching is disabled, ignoring");
+        ap_remove_output_filter(f);
+        return ap_pass_brigade(f->next, in);
     }
 
     reason = NULL;
@@ -379,32 +742,11 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         return APR_SUCCESS;
     }
 
-    /* have we already run the cachability check and set up the
+    /* have we already run the cacheability check and set up the
      * cached file handle?
      */
     if (cache->in_checked) {
-        /* pass the brigades into the cache, then pass them
-         * up the filter stack
-         */
-        rv = cache->provider->store_body(cache->handle, r, in);
-        if (rv != APR_SUCCESS) {
-            ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, r->server,
-                         "cache: Cache provider's store_body failed!");
-            ap_remove_output_filter(f);
-
-            /* give someone else the chance to cache the file */
-            ap_cache_remove_lock(conf, r, cache->handle ?
-                    (char *)cache->handle->cache_obj->key : NULL, NULL);
-        }
-        else {
-
-        	/* proactively remove the lock as soon as we see the eos bucket */
-            ap_cache_remove_lock(conf, r, cache->handle ?
-                    (char *)cache->handle->cache_obj->key : NULL, in);
-
-        }
-
-        return ap_pass_brigade(f->next, in);
+        return cache_save_store(f, in, conf, cache);
     }
 
     /*
@@ -415,6 +757,65 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
      * all. This section is* run before the above section.
      */
 
+    dconf = ap_get_module_config(r->per_dir_config, &cache_module);
+
+    /* RFC2616 13.8 Errors or Incomplete Response Cache Behavior:
+     * If a cache receives a 5xx response while attempting to revalidate an
+     * entry, it MAY either forward this response to the requesting client,
+     * or act as if the server failed to respond. In the latter case, it MAY
+     * return a previously received response unless the cached entry
+     * includes the "must-revalidate" cache-control directive (see section
+     * 14.9).
+     *
+     * This covers the case where an error was generated behind us, for example
+     * by a backend server via mod_proxy.
+     */
+    if (dconf->stale_on_error && r->status >= HTTP_INTERNAL_SERVER_ERROR) {
+
+        ap_remove_output_filter(cache->remove_url_filter);
+
+        if (cache->stale_handle
+                && !cache->stale_handle->cache_obj->info.control.must_revalidate
+                && !cache->stale_handle->cache_obj->info.control.proxy_revalidate) {
+            const char *warn_head;
+
+            /* morph the current save filter into the out filter, and serve from
+             * cache.
+             */
+            cache->handle = cache->stale_handle;
+            if (r->main) {
+                f->frec = cache_out_subreq_filter_handle;
+            }
+            else {
+                f->frec = cache_out_filter_handle;
+            }
+
+            r->headers_out = cache->stale_handle->resp_hdrs;
+
+            ap_set_content_type(r, apr_table_get(
+                    cache->stale_handle->resp_hdrs, "Content-Type"));
+
+            /* add a revalidation warning */
+            warn_head = apr_table_get(r->err_headers_out, "Warning");
+            if ((warn_head == NULL) || ((warn_head != NULL)
+                    && (ap_strstr_c(warn_head, "111") == NULL))) {
+                apr_table_mergen(r->err_headers_out, "Warning",
+                        "111 Revalidation failed");
+            }
+
+            cache_run_cache_status(cache->handle, r, r->headers_out, AP_CACHE_HIT,
+                    apr_psprintf(r->pool,
+                            "cache hit: %d status; stale content returned",
+                            r->status));
+
+            /* give someone else the chance to cache the file */
+            cache_remove_lock(conf, cache, f->r, NULL);
+
+            /* pass brigade to our morphed out filter */
+            return ap_pass_brigade(f, in);
+        }
+    }
+
     /* read expiry date; if a bad date, then leave it so the client can
      * read it
      */
@@ -423,9 +824,7 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         exps = apr_table_get(r->headers_out, "Expires");
     }
     if (exps != NULL) {
-        if (APR_DATE_BAD == (exp = apr_date_parse_http(exps))) {
-            exps = NULL;
-        }
+        exp = apr_date_parse_http(exps);
     }
     else {
         exp = APR_DATE_BAD;
@@ -452,10 +851,27 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         etag = apr_table_get(r->headers_out, "Etag");
     }
     cc_out = apr_table_get(r->err_headers_out, "Cache-Control");
-    if (cc_out == NULL) {
+    pragma = apr_table_get(r->err_headers_out, "Pragma");
+    headers = r->err_headers_out;
+    if (!cc_out && !pragma) {
         cc_out = apr_table_get(r->headers_out, "Cache-Control");
+        pragma = apr_table_get(r->headers_out, "Pragma");
+        headers = r->headers_out;
     }
 
+    /* Have we received a 304 response without any headers at all? Fall back to
+     * the original headers in the original cached request.
+     */
+    if (r->status == HTTP_NOT_MODIFIED && cache->stale_handle && !cc_out
+            && !pragma) {
+        cc_out = apr_table_get(cache->stale_handle->resp_hdrs, "Cache-Control");
+        pragma = apr_table_get(cache->stale_handle->resp_hdrs, "Pragma");
+    }
+
+    /* Parse the cache control header */
+    memset(&control, 0, sizeof(cache_control_t));
+    ap_cache_control(r, &control, cc_out, pragma, headers);
+
     /*
      * what responses should we not cache?
      *
@@ -465,11 +881,13 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
      * They are tested here one by one to be clear and unambiguous.
      */
     if (r->status != HTTP_OK && r->status != HTTP_NON_AUTHORITATIVE
+        && r->status != HTTP_PARTIAL_CONTENT
         && r->status != HTTP_MULTIPLE_CHOICES
         && r->status != HTTP_MOVED_PERMANENTLY
         && r->status != HTTP_NOT_MODIFIED) {
         /* RFC2616 13.4 we are allowed to cache 200, 203, 206, 300, 301 or 410
-         * We don't cache 206, because we don't (yet) cache partial responses.
+         * We allow the caching of 206, but a cache implementation might choose
+         * to decline to cache a 206 if it doesn't know how to.
          * We include 304 Not Modified here too as this is the origin server
          * telling us to serve the cached copy.
          */
@@ -500,14 +918,21 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         /* if a broken Expires header is present, don't cache it */
         reason = apr_pstrcat(p, "Broken expires header: ", exps, NULL);
     }
-    else if (exp != APR_DATE_BAD && exp < r->request_time)
-    {
+    else if (!dconf->store_expired && exp != APR_DATE_BAD
+            && exp < r->request_time) {
         /* if a Expires header is in the past, don't cache it */
-        reason = "Expires header already expired, not cacheable";
-    }
-    else if (!conf->ignorequerystring && r->parsed_uri.query && exps == NULL &&
-             !ap_cache_liststr(NULL, cc_out, "max-age", NULL) &&
-             !ap_cache_liststr(NULL, cc_out, "s-maxage", NULL)) {
+        reason = "Expires header already expired; not cacheable";
+    }
+    else if (!dconf->store_expired && (control.must_revalidate
+            || control.proxy_revalidate) && (!control.s_maxage_value
+            || (!control.s_maxage && !control.max_age_value)) && lastmods
+            == NULL && etag == NULL) {
+        /* if we're already stale, but can never revalidate, don't cache it */
+        reason
+                = "s-maxage or max-age zero and no Last-Modified or Etag; not cacheable";
+    }
+    else if (!conf->ignorequerystring && r->parsed_uri.query && exps == NULL
+            && !control.max_age && !control.s_maxage) {
         /* if a query string is present but no explicit expiration time,
          * don't cache it (RFC 2616/13.9 & 13.2.1)
          */
@@ -520,10 +945,9 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
          */
         reason = "HTTP Status 304 Not Modified";
     }
-    else if (r->status == HTTP_OK && lastmods == NULL && etag == NULL
-             && (exps == NULL) && (conf->no_last_mod_ignore ==0) &&
-             !ap_cache_liststr(NULL, cc_out, "max-age", NULL) &&
-             !ap_cache_liststr(NULL, cc_out, "s-maxage", NULL)) {
+    else if (r->status == HTTP_OK && lastmods == NULL && etag == NULL && (exps
+            == NULL) && (dconf->no_last_mod_ignore == 0) && !control.max_age
+            && !control.s_maxage) {
         /* 200 OK response from HTTP/1.0 and up without Last-Modified,
          * Etag, Expires, Cache-Control:max-age, or Cache-Control:s-maxage
          * headers.
@@ -531,38 +955,25 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         /* Note: mod-include clears last_modified/expires/etags - this
          * is why we have an optional function for a key-gen ;-)
          */
-        reason = "No Last-Modified, Etag, Expires, Cache-Control:max-age or Cache-Control:s-maxage headers";
+        reason = "No Last-Modified; Etag; Expires; Cache-Control:max-age or Cache-Control:s-maxage headers";
     }
-    else if (r->header_only && !cache->stale_handle) {
-        /* Forbid HEAD requests unless we have it cached already */
-        reason = "HTTP HEAD request";
-    }
-    else if (!conf->store_nostore &&
-             ap_cache_liststr(NULL, cc_out, "no-store", NULL)) {
+    else if (!dconf->store_nostore && control.no_store) {
         /* RFC2616 14.9.2 Cache-Control: no-store response
          * indicating do not cache, or stop now if you are
          * trying to cache it.
          */
-        /* FIXME: The Cache-Control: no-store could have come in on a 304,
-         * FIXME: while the original request wasn't conditional.  IOW, we
-         * FIXME:  made the the request conditional earlier to revalidate
-         * FIXME: our cached response.
-         */
         reason = "Cache-Control: no-store present";
     }
-    else if (!conf->store_private &&
-             ap_cache_liststr(NULL, cc_out, "private", NULL)) {
+    else if (!dconf->store_private && control.private) {
         /* RFC2616 14.9.1 Cache-Control: private response
          * this object is marked for this user's eyes only. Behave
          * as a tunnel.
          */
-        /* FIXME: See above (no-store) */
         reason = "Cache-Control: private present";
     }
-    else if (apr_table_get(r->headers_in, "Authorization") != NULL
-             && !(ap_cache_liststr(NULL, cc_out, "s-maxage", NULL)
-                  || ap_cache_liststr(NULL, cc_out, "must-revalidate", NULL)
-                  || ap_cache_liststr(NULL, cc_out, "public", NULL))) {
+    else if (apr_table_get(r->headers_in, "Authorization")
+            && !(control.s_maxage || control.must_revalidate
+                    || control.proxy_revalidate || control.public)) {
         /* RFC2616 14.8 Authorisation:
          * if authorisation is included in the request, we don't cache,
          * but we can cache if the following exceptions are true:
@@ -572,9 +983,7 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
          */
         reason = "Authorization required";
     }
-    else if (ap_cache_liststr(NULL,
-                              apr_table_get(r->headers_out, "Vary"),
-                              "*", NULL)) {
+    else if (ap_find_token(NULL, apr_table_get(r->headers_out, "Vary"), "*")) {
         reason = "Vary header contains '*'";
     }
     else if (apr_table_get(r->subprocess_env, "no-cache") != NULL) {
@@ -619,29 +1028,59 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
             APR_BRIGADE_INSERT_TAIL(bb, bkt);
         }
         else {
+            /* RFC 2616 10.3.5 states that entity headers are not supposed
+             * to be in the 304 response.  Therefore, we need to combine the
+             * response headers with the cached headers *before* we update
+             * the cached headers.
+             *
+             * However, before doing that, we need to first merge in
+             * err_headers_out and we also need to strip any hop-by-hop
+             * headers that might have snuck in.
+             */
+            r->headers_out = ap_cache_cacheable_headers_out(r);
+
+            /* Merge in our cached headers.  However, keep any updated values. */
+            cache_accept_headers(cache->handle, r, 1);
+
             cache->provider->recall_body(cache->handle, r->pool, bb);
+
+            bkt = apr_bucket_eos_create(bb->bucket_alloc);
+            APR_BRIGADE_INSERT_TAIL(bb, bkt);
         }
 
         cache->block_response = 1;
 
+        /* we've got a cache conditional hit! tell anyone who cares */
+        cache_run_cache_status(
+                cache->handle,
+                r,
+                r->headers_out,
+                AP_CACHE_REVALIDATE,
+                apr_psprintf(
+                        r->pool,
+                        "conditional cache hit: 304 was uncacheable though (%s); entity removed",
+                        reason));
+
         /* let someone else attempt to cache */
-        ap_cache_remove_lock(conf, r, cache->handle ?
-                (char *)cache->handle->cache_obj->key : NULL, NULL);
+        cache_remove_lock(conf, cache, r, NULL);
 
         return ap_pass_brigade(f->next, bb);
     }
 
     if (reason) {
-        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
-                     "cache: %s not cached. Reason: %s", r->unparsed_uri,
-                     reason);
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00768)
+                "cache: %s not cached. Reason: %s", r->unparsed_uri,
+                reason);
+
+        /* we've got a cache miss! tell anyone who cares */
+        cache_run_cache_status(cache->handle, r, r->headers_out, AP_CACHE_MISS,
+                reason);
 
         /* remove this filter from the chain */
         ap_remove_output_filter(f);
 
         /* remove the lock file unconditionally */
-        ap_cache_remove_lock(conf, r, cache->handle ?
-                (char *)cache->handle->cache_obj->key : NULL, NULL);
+        cache_remove_lock(conf, cache, r, NULL);
 
         /* ship the data up the stack */
         return ap_pass_brigade(f->next, in);
@@ -668,7 +1107,6 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
          * buckets and use their length to calculate the size
          */
         int all_buckets_here=0;
-        int unresolved_length = 0;
         size=0;
         for (e = APR_BRIGADE_FIRST(in);
              e != APR_BRIGADE_SENTINEL(in);
@@ -679,7 +1117,6 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
                 break;
             }
             if (APR_BUCKET_IS_FLUSH(e)) {
-                unresolved_length = 1;
                 continue;
             }
             if (e->length == (apr_size_t)-1) {
@@ -692,6 +1129,9 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         }
     }
 
+    /* remember content length to check response size against later */
+    cache->size = size;
+
     /* It's safe to cache the response.
      *
      * There are two possiblities at this point:
@@ -706,10 +1146,6 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
      */
 
     /* Did we have a stale cache entry that really is stale?
-     *
-     * Note that for HEAD requests, we won't get the body, so for a stale
-     * HEAD request, we don't remove the entity - instead we let the
-     * CACHE_REMOVE_URL filter remove the stale item from the cache.
      */
     if (cache->stale_handle) {
         if (r->status == HTTP_NOT_MODIFIED) {
@@ -718,7 +1154,7 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
             info = &cache->handle->cache_obj->info;
             rv = OK;
         }
-        else if (!r->header_only) {
+        else {
             /* Oh, well.  Toss it. */
             cache->provider->remove_entity(cache->stale_handle);
             /* Treat the request as if it wasn't conditional. */
@@ -732,30 +1168,33 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         }
     }
 
-    /* no cache handle, create a new entity only for non-HEAD requests */
-    if (!cache->handle && !r->header_only) {
-        rv = cache_create_entity(r, size);
+    /* no cache handle, create a new entity */
+    if (!cache->handle) {
+        rv = cache_create_entity(cache, r, size, in);
         info = apr_pcalloc(r->pool, sizeof(cache_info));
         /* We only set info->status upon the initial creation. */
         info->status = r->status;
     }
 
     if (rv != OK) {
+        /* we've got a cache miss! tell anyone who cares */
+        cache_run_cache_status(cache->handle, r, r->headers_out, AP_CACHE_MISS,
+                "cache miss: create_entity failed");
+
         /* Caching layer declined the opportunity to cache the response */
         ap_remove_output_filter(f);
-        ap_cache_remove_lock(conf, r, cache->handle ?
-                (char *)cache->handle->cache_obj->key : NULL, NULL);
+        cache_remove_lock(conf, cache, r, NULL);
         return ap_pass_brigade(f->next, in);
     }
 
-    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
-                 "cache: Caching url: %s", r->unparsed_uri);
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00769)
+            "cache: Caching url: %s", r->unparsed_uri);
 
     /* We are actually caching this response. So it does not
      * make sense to remove this entity any more.
      */
-    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
-                 "cache: Removing CACHE_REMOVE_URL filter.");
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00770)
+            "cache: Removing CACHE_REMOVE_URL filter.");
     ap_remove_output_filter(cache->remove_url_filter);
 
     /*
@@ -768,6 +1207,9 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
      * too.
      */
 
+    /* store away the previously parsed cache control headers */
+    memcpy(&info->control, &control, sizeof(cache_control_t));
+
     /* Read the date. Generate one if one is not supplied */
     dates = apr_table_get(r->err_headers_out, "Date");
     if (dates == NULL) {
@@ -797,15 +1239,13 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
     if (lastmod != APR_DATE_BAD && lastmod > date) {
         /* if it's in the future, then replace by date */
         lastmod = date;
-        lastmods = dates;
-        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0,
-                     r->server,
-                     "cache: Last modified is in the future, "
-                     "replacing with now");
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0,
+                r, APLOGNO(00771) "cache: Last modified is in the future, "
+                "replacing with now");
     }
 
     /* if no expiry date then
-     *   if Cache-Control: max-age present
+     *   if Cache-Control: max-age
      *      expiry date = date + max-age
      *   else if lastmod
      *      expiry date = date + min((date - lastmod) * factor, maxexpire)
@@ -813,22 +1253,23 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
      *      expire date = date + defaultexpire
      */
     if (exp == APR_DATE_BAD) {
-        char *max_age_val;
 
-        if (ap_cache_liststr(r->pool, cc_out, "max-age", &max_age_val) &&
-            max_age_val != NULL) {
+        if (control.max_age) {
             apr_int64_t x;
 
             errno = 0;
-            x = apr_atoi64(max_age_val);
+            x = control.max_age_value;
             if (errno) {
-                x = conf->defex;
+                x = dconf->defex;
             }
             else {
                 x = x * MSEC_ONE_SEC;
             }
-            if (x > conf->maxex) {
-                x = conf->maxex;
+            if (x < dconf->minex) {
+                x = dconf->minex;
+            }
+            if (x > dconf->maxex) {
+                x = dconf->maxex;
             }
             exp = date + x;
         }
@@ -837,15 +1278,18 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
              * an expiration time of now. This causes some problems with
              * freshness calculations, so we choose the else path...
              */
-            apr_time_t x = (apr_time_t) ((date - lastmod) * conf->factor);
+            apr_time_t x = (apr_time_t) ((date - lastmod) * dconf->factor);
 
-            if (x > conf->maxex) {
-                x = conf->maxex;
+            if (x < dconf->minex) {
+                x = dconf->minex;
+            }
+            if (x > dconf->maxex) {
+                x = dconf->maxex;
             }
             exp = date + x;
         }
         else {
-            exp = date + conf->defex;
+            exp = date + dconf->defex;
         }
     }
     info->expire = exp;
@@ -865,14 +1309,10 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
          * err_headers_out and we also need to strip any hop-by-hop
          * headers that might have snuck in.
          */
-        r->headers_out = apr_table_overlay(r->pool, r->headers_out,
-                                           r->err_headers_out);
-        r->headers_out = ap_cache_cacheable_hdrs_out(r->pool, r->headers_out,
-                                                     r->server);
-        apr_table_clear(r->err_headers_out);
+        r->headers_out = ap_cache_cacheable_headers_out(r);
 
         /* Merge in our cached headers.  However, keep any updated values. */
-        ap_cache_accept_headers(cache->handle, r, 1);
+        cache_accept_headers(cache->handle, r, 1);
     }
 
     /* Write away header information to cache. It is possible that we are
@@ -895,6 +1335,13 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         apr_bucket *bkt;
         int status;
 
+        /* We're just saving response headers, so we are done. Commit
+         * the response at this point, unless there was a previous error.
+         */
+        if (rv == APR_SUCCESS) {
+            rv = cache->provider->commit_entity(cache->handle, r);
+        }
+
         bb = apr_brigade_create(r->pool, r->connection->bucket_alloc);
 
         /* Restore the original request headers and see if we need to
@@ -911,6 +1358,9 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         }
         else {
             cache->provider->recall_body(cache->handle, r->pool, bb);
+
+            bkt = apr_bucket_eos_create(bb->bucket_alloc);
+            APR_BRIGADE_INSERT_TAIL(bb, bkt);
         }
 
         cache->block_response = 1;
@@ -921,58 +1371,63 @@ static int cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
          * the body it is safe to try and remove the url from the cache.
          */
         if (rv != APR_SUCCESS) {
-            ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, r->server,
-                         "cache: updating headers with store_headers failed. "
-                         "Removing cached url.");
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv, r, APLOGNO(00772)
+                    "cache: updating headers with store_headers failed. "
+                    "Removing cached url.");
 
-            rv = cache->provider->remove_url(cache->stale_handle, r->pool);
+            rv = cache->provider->remove_url(cache->stale_handle, r);
             if (rv != OK) {
-                /* Probably a mod_disk_cache cache area has been (re)mounted
+                /* Probably a mod_cache_disk cache area has been (re)mounted
                  * read-only, or that there is a permissions problem.
                  */
-                ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, r->server,
-                     "cache: attempt to remove url from cache unsuccessful.");
+                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv, r, APLOGNO(00773)
+                        "cache: attempt to remove url from cache unsuccessful.");
             }
 
+            /* we've got a cache conditional hit! tell anyone who cares */
+            cache_run_cache_status(cache->handle, r, r->headers_out,
+                    AP_CACHE_REVALIDATE,
+                    "conditional cache hit: entity refresh failed");
+
+        }
+        else {
+
+            /* we've got a cache conditional hit! tell anyone who cares */
+            cache_run_cache_status(cache->handle, r, r->headers_out,
+                    AP_CACHE_REVALIDATE,
+                    "conditional cache hit: entity refreshed");
+
         }
 
         /* let someone else attempt to cache */
-        ap_cache_remove_lock(conf, r, cache->handle ?
-                (char *)cache->handle->cache_obj->key : NULL, NULL);
+        cache_remove_lock(conf, cache, r, NULL);
 
         return ap_pass_brigade(f->next, bb);
     }
 
     if (rv != APR_SUCCESS) {
-        ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, r->server,
-                     "cache: store_headers failed");
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv, r, APLOGNO(00774)
+                "cache: store_headers failed");
 
-        ap_remove_output_filter(f);
-        ap_cache_remove_lock(conf, r, cache->handle ?
-                (char *)cache->handle->cache_obj->key : NULL, NULL);
-        return ap_pass_brigade(f->next, in);
-    }
+        /* we've got a cache miss! tell anyone who cares */
+        cache_run_cache_status(cache->handle, r, r->headers_out, AP_CACHE_MISS,
+                "cache miss: store_headers failed");
 
-    rv = cache->provider->store_body(cache->handle, r, in);
-    if (rv != APR_SUCCESS) {
-        ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, r->server,
-                     "cache: store_body failed");
         ap_remove_output_filter(f);
-        ap_cache_remove_lock(conf, r, cache->handle ?
-                (char *)cache->handle->cache_obj->key : NULL, NULL);
+        cache_remove_lock(conf, cache, r, NULL);
         return ap_pass_brigade(f->next, in);
     }
 
-    /* proactively remove the lock as soon as we see the eos bucket */
-    ap_cache_remove_lock(conf, r, cache->handle ?
-            (char *)cache->handle->cache_obj->key : NULL, in);
+    /* we've got a cache miss! tell anyone who cares */
+    cache_run_cache_status(cache->handle, r, r->headers_out, AP_CACHE_MISS,
+            "cache miss: attempting entity save");
 
-    return ap_pass_brigade(f->next, in);
+    return cache_save_store(f, in, conf, cache);
 }
 
 /*
  * CACHE_REMOVE_URL filter
- * ---------------
+ * -----------------------
  *
  * This filter gets added in the quick handler every time the CACHE_SAVE filter
  * gets inserted. Its purpose is to remove a confirmed stale cache entry from
@@ -1005,23 +1460,309 @@ static int cache_remove_url_filter(ap_filter_t *f, apr_bucket_brigade *in)
          * 1. Remove ourselves
          * 2. Do nothing and bail out
          */
-        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
-                     "cache: CACHE_REMOVE_URL enabled unexpectedly");
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00775)
+                "cache: CACHE_REMOVE_URL enabled unexpectedly");
         ap_remove_output_filter(f);
         return ap_pass_brigade(f->next, in);
     }
 
     /* Now remove this cache entry from the cache */
-    cache_remove_url(cache, r->pool);
+    cache_remove_url(cache, r);
 
     /* remove ourselves */
     ap_remove_output_filter(f);
     return ap_pass_brigade(f->next, in);
 }
 
+/*
+ * CACHE filter
+ * ------------
+ *
+ * This filter can be optionally inserted into the filter chain by the admin as
+ * a marker representing the precise location within the filter chain where
+ * caching is to be performed.
+ *
+ * When the filter chain is set up in the non-quick version of the URL handler,
+ * the CACHE filter is replaced by the CACHE_OUT or CACHE_SAVE filter,
+ * effectively inserting the caching filters at the point indicated by the
+ * admin. The CACHE filter is then removed.
+ *
+ * This allows caching to be performed before the content is passed to the
+ * INCLUDES filter, or to a filter that might perform transformations unique
+ * to the specific request and that would otherwise be non-cacheable.
+ */
+static int cache_filter(ap_filter_t *f, apr_bucket_brigade *in)
+{
+
+    cache_server_conf
+            *conf =
+                    (cache_server_conf *) ap_get_module_config(f->r->server->module_config,
+                            &cache_module);
+
+    /* was the quick handler enabled */
+    if (conf->quick) {
+        ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, f->r, APLOGNO(00776)
+                "cache: CACHE filter was added in quick handler mode and "
+                "will be ignored: %s", f->r->unparsed_uri);
+    }
+    /* otherwise we may have been bypassed, nothing to see here */
+    else {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, f->r, APLOGNO(00777)
+                "cache: CACHE filter was added twice, or was added where "
+                "the cache has been bypassed and will be ignored: %s",
+                f->r->unparsed_uri);
+    }
+
+    /* we are just a marker, so let's just remove ourselves */
+    ap_remove_output_filter(f);
+    return ap_pass_brigade(f->next, in);
+}
+
+/**
+ * If configured, add the status of the caching attempt to the subprocess
+ * environment, and if configured, to headers in the response.
+ *
+ * The status is saved below the broad category of the status (hit, miss,
+ * revalidate), as well as a single cache-status key. This can be used for
+ * conditional logging.
+ *
+ * The status is optionally saved to an X-Cache header, and the detail of
+ * why a particular cache entry was cached (or not cached) is optionally
+ * saved to an X-Cache-Detail header. This extra detail is useful for
+ * service developers who may need to know whether their Cache-Control headers
+ * are working correctly.
+ */
+static int cache_status(cache_handle_t *h, request_rec *r,
+        apr_table_t *headers, ap_cache_status_e status, const char *reason)
+{
+    cache_server_conf
+            *conf =
+                    (cache_server_conf *) ap_get_module_config(r->server->module_config,
+                            &cache_module);
+
+    cache_dir_conf *dconf = ap_get_module_config(r->per_dir_config, &cache_module);
+    int x_cache = 0, x_cache_detail = 0;
+
+    switch (status) {
+    case AP_CACHE_HIT: {
+        apr_table_setn(r->subprocess_env, AP_CACHE_HIT_ENV, reason);
+        break;
+    }
+    case AP_CACHE_REVALIDATE: {
+        apr_table_setn(r->subprocess_env, AP_CACHE_REVALIDATE_ENV, reason);
+        break;
+    }
+    case AP_CACHE_MISS: {
+        apr_table_setn(r->subprocess_env, AP_CACHE_MISS_ENV, reason);
+        break;
+    }
+    case AP_CACHE_INVALIDATE: {
+        apr_table_setn(r->subprocess_env, AP_CACHE_INVALIDATE_ENV, reason);
+        break;
+    }
+    }
+
+    apr_table_setn(r->subprocess_env, AP_CACHE_STATUS_ENV, reason);
+
+    if (dconf && dconf->x_cache_set) {
+        x_cache = dconf->x_cache;
+    }
+    else {
+        x_cache = conf->x_cache;
+    }
+    if (x_cache) {
+        apr_table_setn(headers, "X-Cache",
+                apr_psprintf(r->pool, "%s from %s",
+                        status == AP_CACHE_HIT ? "HIT" : status
+                                == AP_CACHE_REVALIDATE ? "REVALIDATE" : "MISS",
+                        r->server->server_hostname));
+    }
+
+    if (dconf && dconf->x_cache_detail_set) {
+        x_cache_detail = dconf->x_cache_detail;
+    }
+    else {
+        x_cache_detail = conf->x_cache_detail;
+    }
+    if (x_cache_detail) {
+        apr_table_setn(headers, "X-Cache-Detail", apr_psprintf(r->pool,
+                "\"%s\" from %s", reason, r->server->server_hostname));
+    }
+
+    return OK;
+}
+
+/**
+ * If an error has occurred, but we have a stale cached entry, restore the
+ * filter stack from the save filter onwards. The canned error message will
+ * be discarded in the process, and replaced with the cached response.
+ */
+static void cache_insert_error_filter(request_rec *r)
+{
+    void *dummy;
+    cache_dir_conf *dconf;
+
+    /* ignore everything except for 5xx errors */
+    if (r->status < HTTP_INTERNAL_SERVER_ERROR) {
+        return;
+    }
+
+    dconf = ap_get_module_config(r->per_dir_config, &cache_module);
+
+    if (!dconf->stale_on_error) {
+        return;
+    }
+
+    /* RFC2616 13.8 Errors or Incomplete Response Cache Behavior:
+     * If a cache receives a 5xx response while attempting to revalidate an
+     * entry, it MAY either forward this response to the requesting client,
+     * or act as if the server failed to respond. In the latter case, it MAY
+     * return a previously received response unless the cached entry
+     * includes the "must-revalidate" cache-control directive (see section
+     * 14.9).
+     *
+     * This covers the case where the error was generated by our server via
+     * ap_die().
+     */
+    apr_pool_userdata_get(&dummy, CACHE_CTX_KEY, r->pool);
+    if (dummy) {
+        cache_request_rec *cache = (cache_request_rec *) dummy;
+
+        ap_remove_output_filter(cache->remove_url_filter);
+
+        if (cache->stale_handle && cache->save_filter
+                && !cache->stale_handle->cache_obj->info.control.must_revalidate
+                && !cache->stale_handle->cache_obj->info.control.proxy_revalidate) {
+            const char *warn_head;
+            cache_server_conf
+                    *conf =
+                            (cache_server_conf *) ap_get_module_config(r->server->module_config,
+                                    &cache_module);
+
+            /* morph the current save filter into the out filter, and serve from
+             * cache.
+             */
+            cache->handle = cache->stale_handle;
+            if (r->main) {
+                cache->save_filter->frec = cache_out_subreq_filter_handle;
+            }
+            else {
+                cache->save_filter->frec = cache_out_filter_handle;
+            }
+
+            r->output_filters = cache->save_filter;
+
+            r->err_headers_out = cache->stale_handle->resp_hdrs;
+
+            /* add a revalidation warning */
+            warn_head = apr_table_get(r->err_headers_out, "Warning");
+            if ((warn_head == NULL) || ((warn_head != NULL)
+                    && (ap_strstr_c(warn_head, "111") == NULL))) {
+                apr_table_mergen(r->err_headers_out, "Warning",
+                        "111 Revalidation failed");
+            }
+
+            cache_run_cache_status(
+                    cache->handle,
+                    r,
+                    r->err_headers_out,
+                    AP_CACHE_HIT,
+                    apr_psprintf(
+                            r->pool,
+                            "cache hit: %d status; stale content returned",
+                            r->status));
+
+            /* give someone else the chance to cache the file */
+            cache_remove_lock(conf, cache, r, NULL);
+
+        }
+    }
+
+    return;
+}
+
 /* -------------------------------------------------------------- */
 /* Setup configurable data */
 
+static void *create_dir_config(apr_pool_t *p, char *dummy)
+{
+    cache_dir_conf *dconf = apr_pcalloc(p, sizeof(cache_dir_conf));
+
+    dconf->no_last_mod_ignore = 0;
+    dconf->store_expired = 0;
+    dconf->store_private = 0;
+    dconf->store_nostore = 0;
+
+    /* maximum time to cache a document */
+    dconf->maxex = DEFAULT_CACHE_MAXEXPIRE;
+    dconf->minex = DEFAULT_CACHE_MINEXPIRE;
+    /* default time to cache a document */
+    dconf->defex = DEFAULT_CACHE_EXPIRE;
+
+    /* factor used to estimate Expires date from LastModified date */
+    dconf->factor = DEFAULT_CACHE_LMFACTOR;
+
+    dconf->x_cache = DEFAULT_X_CACHE;
+    dconf->x_cache_detail = DEFAULT_X_CACHE_DETAIL;
+
+    dconf->stale_on_error = DEFAULT_CACHE_STALE_ON_ERROR;
+
+    /* array of providers for this URL space */
+    dconf->cacheenable = apr_array_make(p, 10, sizeof(struct cache_enable));
+
+    return dconf;
+}
+
+static void *merge_dir_config(apr_pool_t *p, void *basev, void *addv) {
+    cache_dir_conf *new = (cache_dir_conf *) apr_pcalloc(p, sizeof(cache_dir_conf));
+    cache_dir_conf *add = (cache_dir_conf *) addv;
+    cache_dir_conf *base = (cache_dir_conf *) basev;
+
+    new->no_last_mod_ignore = (add->no_last_mod_ignore_set == 0) ? base->no_last_mod_ignore : add->no_last_mod_ignore;
+    new->no_last_mod_ignore_set = add->no_last_mod_ignore_set || base->no_last_mod_ignore_set;
+
+    new->store_expired = (add->store_expired_set == 0) ? base->store_expired : add->store_expired;
+    new->store_expired_set = add->store_expired_set || base->store_expired_set;
+    new->store_private = (add->store_private_set == 0) ? base->store_private : add->store_private;
+    new->store_private_set = add->store_private_set || base->store_private_set;
+    new->store_nostore = (add->store_nostore_set == 0) ? base->store_nostore : add->store_nostore;
+    new->store_nostore_set = add->store_nostore_set || base->store_nostore_set;
+
+    /* maximum time to cache a document */
+    new->maxex = (add->maxex_set == 0) ? base->maxex : add->maxex;
+    new->maxex_set = add->maxex_set || base->maxex_set;
+    new->minex = (add->minex_set == 0) ? base->minex : add->minex;
+    new->minex_set = add->minex_set || base->minex_set;
+
+    /* default time to cache a document */
+    new->defex = (add->defex_set == 0) ? base->defex : add->defex;
+    new->defex_set = add->defex_set || base->defex_set;
+
+    /* factor used to estimate Expires date from LastModified date */
+    new->factor = (add->factor_set == 0) ? base->factor : add->factor;
+    new->factor_set = add->factor_set || base->factor_set;
+
+    new->x_cache = (add->x_cache_set == 0) ? base->x_cache : add->x_cache;
+    new->x_cache_set = add->x_cache_set || base->x_cache_set;
+    new->x_cache_detail = (add->x_cache_detail_set == 0) ? base->x_cache_detail
+            : add->x_cache_detail;
+    new->x_cache_detail_set = add->x_cache_detail_set
+            || base->x_cache_detail_set;
+
+    new->stale_on_error = (add->stale_on_error_set == 0) ? base->stale_on_error
+            : add->stale_on_error;
+    new->stale_on_error_set = add->stale_on_error_set
+            || base->stale_on_error_set;
+
+    new->cacheenable = add->enable_set ? apr_array_append(p, base->cacheenable,
+            add->cacheenable) : base->cacheenable;
+    new->enable_set = add->enable_set || base->enable_set;
+    new->disable = (add->disable_set == 0) ? base->disable : add->disable;
+    new->disable_set = add->disable_set || base->disable_set;
+
+    return new;
+}
+
 static void * create_cache_config(apr_pool_t *p, server_rec *s)
 {
     const char *tmppath;
@@ -1031,29 +1772,17 @@ static void * create_cache_config(apr_pool_t *p, server_rec *s)
     ps->cacheenable = apr_array_make(p, 10, sizeof(struct cache_enable));
     /* array of URL prefixes for which caching is disabled */
     ps->cachedisable = apr_array_make(p, 10, sizeof(struct cache_disable));
-    /* maximum time to cache a document */
-    ps->maxex = DEFAULT_CACHE_MAXEXPIRE;
-    ps->maxex_set = 0;
-    /* default time to cache a document */
-    ps->defex = DEFAULT_CACHE_EXPIRE;
-    ps->defex_set = 0;
-    /* factor used to estimate Expires date from LastModified date */
-    ps->factor = DEFAULT_CACHE_LMFACTOR;
-    ps->factor_set = 0;
-    ps->no_last_mod_ignore_set = 0;
-    ps->no_last_mod_ignore = 0;
     ps->ignorecachecontrol = 0;
     ps->ignorecachecontrol_set = 0;
-    ps->store_private = 0;
-    ps->store_private_set = 0;
-    ps->store_nostore = 0;
-    ps->store_nostore_set = 0;
     /* array of headers that should not be stored in cache */
     ps->ignore_headers = apr_array_make(p, 10, sizeof(char *));
     ps->ignore_headers_set = CACHE_IGNORE_HEADERS_UNSET;
     /* flag indicating that query-string should be ignored when caching */
     ps->ignorequerystring = 0;
     ps->ignorequerystring_set = 0;
+    /* by default, run in the quick handler */
+    ps->quick = 1;
+    ps->quick_set = 0;
     /* array of identifiers that should not be used for key calculation */
     ps->ignore_session_id = apr_array_make(p, 10, sizeof(char *));
     ps->ignore_session_id_set = CACHE_IGNORE_SESSION_ID_UNSET;
@@ -1064,6 +1793,8 @@ static void * create_cache_config(apr_pool_t *p, server_rec *s)
         ps->lockpath = apr_pstrcat(p, tmppath, DEFAULT_CACHE_LOCKPATH, NULL);
     }
     ps->lockmaxage = apr_time_from_sec(DEFAULT_CACHE_MAXAGE);
+    ps->x_cache = DEFAULT_X_CACHE;
+    ps->x_cache_detail = DEFAULT_X_CACHE_DETAIL;
     return ps;
 }
 
@@ -1081,30 +1812,11 @@ static void * merge_cache_config(apr_pool_t *p, void *basev, void *overridesv)
     ps->cacheenable = apr_array_append(p,
                                        base->cacheenable,
                                        overrides->cacheenable);
-    /* maximum time to cache a document */
-    ps->maxex = (overrides->maxex_set == 0) ? base->maxex : overrides->maxex;
-    /* default time to cache a document */
-    ps->defex = (overrides->defex_set == 0) ? base->defex : overrides->defex;
-    /* factor used to estimate Expires date from LastModified date */
-    ps->factor =
-        (overrides->factor_set == 0) ? base->factor : overrides->factor;
 
-    ps->no_last_mod_ignore =
-        (overrides->no_last_mod_ignore_set == 0)
-        ? base->no_last_mod_ignore
-        : overrides->no_last_mod_ignore;
     ps->ignorecachecontrol  =
         (overrides->ignorecachecontrol_set == 0)
         ? base->ignorecachecontrol
         : overrides->ignorecachecontrol;
-    ps->store_private  =
-        (overrides->store_private_set == 0)
-        ? base->store_private
-        : overrides->store_private;
-    ps->store_nostore  =
-        (overrides->store_nostore_set == 0)
-        ? base->store_nostore
-        : overrides->store_nostore;
     ps->ignore_headers =
         (overrides->ignore_headers_set == CACHE_IGNORE_HEADERS_UNSET)
         ? base->ignore_headers
@@ -1129,18 +1841,47 @@ static void * merge_cache_config(apr_pool_t *p, void *basev, void *overridesv)
         (overrides->lockmaxage_set == 0)
         ? base->lockmaxage
         : overrides->lockmaxage;
+    ps->quick =
+        (overrides->quick_set == 0)
+        ? base->quick
+        : overrides->quick;
+    ps->x_cache =
+        (overrides->x_cache_set == 0)
+        ? base->x_cache
+        : overrides->x_cache;
+    ps->x_cache_detail =
+        (overrides->x_cache_detail_set == 0)
+        ? base->x_cache_detail
+        : overrides->x_cache_detail;
+    ps->base_uri =
+        (overrides->base_uri_set == 0)
+        ? base->base_uri
+        : overrides->base_uri;
     return ps;
 }
-static const char *set_cache_ignore_no_last_mod(cmd_parms *parms, void *dummy,
-                                                int flag)
+
+static const char *set_cache_quick_handler(cmd_parms *parms, void *dummy,
+                                           int flag)
 {
     cache_server_conf *conf;
 
     conf =
-        (cache_server_conf *)ap_get_module_config(parms->server->module_config,
+        (cache_server_conf *)ap_get_module_config(parms->server->module_config
+,
                                                   &cache_module);
-    conf->no_last_mod_ignore = flag;
-    conf->no_last_mod_ignore_set = 1;
+    conf->quick = flag;
+    conf->quick_set = 1;
+    return NULL;
+
+}
+
+static const char *set_cache_ignore_no_last_mod(cmd_parms *parms, void *dummy,
+                                                int flag)
+{
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
+
+    dconf->no_last_mod_ignore = flag;
+    dconf->no_last_mod_ignore_set = 1;
     return NULL;
 
 }
@@ -1158,29 +1899,33 @@ static const char *set_cache_ignore_cachecontrol(cmd_parms *parms,
     return NULL;
 }
 
+static const char *set_cache_store_expired(cmd_parms *parms, void *dummy,
+                                           int flag)
+{
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
+
+    dconf->store_expired = flag;
+    dconf->store_expired_set = 1;
+    return NULL;
+}
+
 static const char *set_cache_store_private(cmd_parms *parms, void *dummy,
                                            int flag)
 {
-    cache_server_conf *conf;
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
 
-    conf =
-        (cache_server_conf *)ap_get_module_config(parms->server->module_config,
-                                                  &cache_module);
-    conf->store_private = flag;
-    conf->store_private_set = 1;
+    dconf->store_private = flag;
+    dconf->store_private_set = 1;
     return NULL;
 }
 
 static const char *set_cache_store_nostore(cmd_parms *parms, void *dummy,
                                            int flag)
 {
-    cache_server_conf *conf;
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
 
-    conf =
-        (cache_server_conf *)ap_get_module_config(parms->server->module_config,
-                                                  &cache_module);
-    conf->store_nostore = flag;
-    conf->store_nostore_set = 1;
+    dconf->store_nostore = flag;
+    dconf->store_nostore_set = 1;
     return NULL;
 }
 
@@ -1193,7 +1938,7 @@ static const char *add_ignore_header(cmd_parms *parms, void *dummy,
     conf =
         (cache_server_conf *)ap_get_module_config(parms->server->module_config,
                                                   &cache_module);
-    if (!strncasecmp(header, "None", 4)) {
+    if (!strcasecmp(header, "None")) {
         /* if header None is listed clear array */
         conf->ignore_headers->nelts = 0;
     }
@@ -1221,7 +1966,7 @@ static const char *add_ignore_session_id(cmd_parms *parms, void *dummy,
     conf =
         (cache_server_conf *)ap_get_module_config(parms->server->module_config,
                                                   &cache_module);
-    if (!strncasecmp(identifier, "None", 4)) {
+    if (!strcasecmp(identifier, "None")) {
         /* if identifier None is listed clear array */
         conf->ignore_session_id->nelts = 0;
     }
@@ -1244,19 +1989,46 @@ static const char *add_cache_enable(cmd_parms *parms, void *dummy,
                                     const char *type,
                                     const char *url)
 {
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
     cache_server_conf *conf;
     struct cache_enable *new;
 
+    const char *err = ap_check_cmd_context(parms,
+                                           NOT_IN_DIRECTORY|NOT_IN_LIMIT|NOT_IN_FILES);
+    if (err != NULL) {
+        return err;
+    }
+
     if (*type == '/') {
         return apr_psprintf(parms->pool,
           "provider (%s) starts with a '/'.  Are url and provider switched?",
           type);
     }
 
+    if (!url) {
+        url = parms->path;
+    }
+    if (!url) {
+        return apr_psprintf(parms->pool,
+          "CacheEnable provider (%s) is missing an URL.", type);
+    }
+    if (parms->path && strncmp(parms->path, url, strlen(parms->path))) {
+        return "When in a Location, CacheEnable must specify a path or an URL below "
+        "that location.";
+    }
+
     conf =
         (cache_server_conf *)ap_get_module_config(parms->server->module_config,
                                                   &cache_module);
-    new = apr_array_push(conf->cacheenable);
+
+    if (parms->path) {
+        new = apr_array_push(dconf->cacheenable);
+        dconf->enable_set = 1;
+    }
+    else {
+        new = apr_array_push(conf->cacheenable);
+    }
+
     new->type = type;
     if (apr_uri_parse(parms->pool, url, &(new->url))) {
         return NULL;
@@ -1273,12 +2045,35 @@ static const char *add_cache_enable(cmd_parms *parms, void *dummy,
 static const char *add_cache_disable(cmd_parms *parms, void *dummy,
                                      const char *url)
 {
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
     cache_server_conf *conf;
     struct cache_disable *new;
 
+    const char *err = ap_check_cmd_context(parms,
+                                           NOT_IN_DIRECTORY|NOT_IN_LIMIT|NOT_IN_FILES);
+    if (err != NULL) {
+        return err;
+    }
+
     conf =
         (cache_server_conf *)ap_get_module_config(parms->server->module_config,
                                                   &cache_module);
+
+    if (parms->path) {
+        if (!strcmp(url, "on")) {
+            dconf->disable = 1;
+            dconf->disable_set = 1;
+            return NULL;
+        }
+        else {
+            return "CacheDisable must be followed by the word 'on' when in a Location.";
+        }
+    }
+
+    if (!url || (url[0] != '/' && !ap_strchr_c(url, ':'))) {
+        return "CacheDisable must specify a path or an URL.";
+    }
+
     new = apr_array_push(conf->cachedisable);
     if (apr_uri_parse(parms->pool, url, &(new->url))) {
         return NULL;
@@ -1295,43 +2090,44 @@ static const char *add_cache_disable(cmd_parms *parms, void *dummy,
 static const char *set_cache_maxex(cmd_parms *parms, void *dummy,
                                    const char *arg)
 {
-    cache_server_conf *conf;
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
 
-    conf =
-        (cache_server_conf *)ap_get_module_config(parms->server->module_config,
-                                                  &cache_module);
-    conf->maxex = (apr_time_t) (atol(arg) * MSEC_ONE_SEC);
-    conf->maxex_set = 1;
+    dconf->maxex = (apr_time_t) (atol(arg) * MSEC_ONE_SEC);
+    dconf->maxex_set = 1;
+    return NULL;
+}
+
+static const char *set_cache_minex(cmd_parms *parms, void *dummy,
+                                   const char *arg)
+{
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
+
+    dconf->minex = (apr_time_t) (atol(arg) * MSEC_ONE_SEC);
+    dconf->minex_set = 1;
     return NULL;
 }
 
 static const char *set_cache_defex(cmd_parms *parms, void *dummy,
                                    const char *arg)
 {
-    cache_server_conf *conf;
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
 
-    conf =
-        (cache_server_conf *)ap_get_module_config(parms->server->module_config,
-                                                  &cache_module);
-    conf->defex = (apr_time_t) (atol(arg) * MSEC_ONE_SEC);
-    conf->defex_set = 1;
+    dconf->defex = (apr_time_t) (atol(arg) * MSEC_ONE_SEC);
+    dconf->defex_set = 1;
     return NULL;
 }
 
 static const char *set_cache_factor(cmd_parms *parms, void *dummy,
                                     const char *arg)
 {
-    cache_server_conf *conf;
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
     double val;
 
-    conf =
-        (cache_server_conf *)ap_get_module_config(parms->server->module_config,
-                                                  &cache_module);
     if (sscanf(arg, "%lg", &val) != 1) {
         return "CacheLastModifiedFactor value must be a float";
     }
-    conf->factor = val;
-    conf->factor_set = 1;
+    dconf->factor = val;
+    dconf->factor_set = 1;
     return NULL;
 }
 
@@ -1397,6 +2193,84 @@ static const char *set_cache_lock_maxage(cmd_parms *parms, void *dummy,
     return NULL;
 }
 
+static const char *set_cache_x_cache(cmd_parms *parms, void *dummy, int flag)
+{
+
+    if (parms->path) {
+        cache_dir_conf *dconf = (cache_dir_conf *)dummy;
+
+        dconf->x_cache = flag;
+        dconf->x_cache_set = 1;
+
+    }
+    else {
+        cache_server_conf *conf =
+            (cache_server_conf *)ap_get_module_config(parms->server->module_config,
+                                                      &cache_module);
+
+        conf->x_cache = flag;
+        conf->x_cache_set = 1;
+
+    }
+
+    return NULL;
+}
+
+static const char *set_cache_x_cache_detail(cmd_parms *parms, void *dummy, int flag)
+{
+
+    if (parms->path) {
+        cache_dir_conf *dconf = (cache_dir_conf *)dummy;
+
+        dconf->x_cache_detail = flag;
+        dconf->x_cache_detail_set = 1;
+
+    }
+    else {
+        cache_server_conf *conf =
+            (cache_server_conf *)ap_get_module_config(parms->server->module_config,
+                                                      &cache_module);
+
+        conf->x_cache_detail = flag;
+        conf->x_cache_detail_set = 1;
+
+    }
+
+    return NULL;
+}
+
+static const char *set_cache_key_base_url(cmd_parms *parms, void *dummy,
+        const char *arg)
+{
+    cache_server_conf *conf;
+    apr_status_t rv;
+
+    conf =
+        (cache_server_conf *)ap_get_module_config(parms->server->module_config,
+                                                  &cache_module);
+    conf->base_uri = apr_pcalloc(parms->pool, sizeof(apr_uri_t));
+    rv = apr_uri_parse(parms->pool, arg, conf->base_uri);
+    if (rv != APR_SUCCESS) {
+        return apr_psprintf(parms->pool, "Could not parse '%s' as an URL.", arg);
+    }
+    else if (!conf->base_uri->scheme && !conf->base_uri->hostname &&
+            !conf->base_uri->port_str) {
+        return apr_psprintf(parms->pool, "URL '%s' must contain at least one of a scheme, a hostname or a port.", arg);
+    }
+    conf->base_uri_set = 1;
+    return NULL;
+}
+
+static const char *set_cache_stale_on_error(cmd_parms *parms, void *dummy,
+        int flag)
+{
+    cache_dir_conf *dconf = (cache_dir_conf *)dummy;
+
+    dconf->stale_on_error = flag;
+    dconf->stale_on_error_set = 1;
+    return NULL;
+}
+
 static int cache_post_config(apr_pool_t *p, apr_pool_t *plog,
                              apr_pool_t *ptemp, server_rec *s)
 {
@@ -1422,26 +2296,35 @@ static const command_rec cache_cmds[] =
      * This is more intuitive that requiring a LoadModule directive.
      */
 
-    AP_INIT_TAKE2("CacheEnable", add_cache_enable, NULL, RSRC_CONF,
-                  "A cache type and partial URL prefix below which "
-                  "caching is enabled"),
-    AP_INIT_TAKE1("CacheDisable", add_cache_disable, NULL, RSRC_CONF,
+    AP_INIT_TAKE12("CacheEnable", add_cache_enable, NULL, RSRC_CONF|ACCESS_CONF,
+                   "A cache type and partial URL prefix below which "
+                   "caching is enabled"),
+    AP_INIT_TAKE1("CacheDisable", add_cache_disable, NULL, RSRC_CONF|ACCESS_CONF,
                   "A partial URL prefix below which caching is disabled"),
-    AP_INIT_TAKE1("CacheMaxExpire", set_cache_maxex, NULL, RSRC_CONF,
+    AP_INIT_TAKE1("CacheMaxExpire", set_cache_maxex, NULL, RSRC_CONF|ACCESS_CONF,
                   "The maximum time in seconds to cache a document"),
-    AP_INIT_TAKE1("CacheDefaultExpire", set_cache_defex, NULL, RSRC_CONF,
+    AP_INIT_TAKE1("CacheMinExpire", set_cache_minex, NULL, RSRC_CONF|ACCESS_CONF,
+                  "The minimum time in seconds to cache a document"),
+    AP_INIT_TAKE1("CacheDefaultExpire", set_cache_defex, NULL, RSRC_CONF|ACCESS_CONF,
                   "The default time in seconds to cache a document"),
-    AP_INIT_FLAG("CacheIgnoreNoLastMod", set_cache_ignore_no_last_mod, NULL,
+    AP_INIT_FLAG("CacheQuickHandler", set_cache_quick_handler, NULL,
                  RSRC_CONF,
+                 "Run the cache in the quick handler, default on"),
+    AP_INIT_FLAG("CacheIgnoreNoLastMod", set_cache_ignore_no_last_mod, NULL,
+                 RSRC_CONF|ACCESS_CONF,
                  "Ignore Responses where there is no Last Modified Header"),
     AP_INIT_FLAG("CacheIgnoreCacheControl", set_cache_ignore_cachecontrol,
                  NULL, RSRC_CONF,
                  "Ignore requests from the client for uncached content"),
+    AP_INIT_FLAG("CacheStoreExpired", set_cache_store_expired,
+                 NULL, RSRC_CONF|ACCESS_CONF,
+                 "Ignore expiration dates when populating cache, resulting in "
+                 "an If-Modified-Since request to the backend on retrieval"),
     AP_INIT_FLAG("CacheStorePrivate", set_cache_store_private,
-                 NULL, RSRC_CONF,
+                 NULL, RSRC_CONF|ACCESS_CONF,
                  "Ignore 'Cache-Control: private' and store private content"),
     AP_INIT_FLAG("CacheStoreNoStore", set_cache_store_nostore,
-                 NULL, RSRC_CONF,
+                 NULL, RSRC_CONF|ACCESS_CONF,
                  "Ignore 'Cache-Control: no-store' and store sensitive content"),
     AP_INIT_ITERATE("CacheIgnoreHeaders", add_ignore_header, NULL, RSRC_CONF,
                     "A space separated list of headers that should not be "
@@ -1453,7 +2336,7 @@ static const command_rec cache_cmds[] =
                     NULL, RSRC_CONF, "A space separated list of session "
                     "identifiers that should be ignored for creating the key "
                     "of the cached entity."),
-    AP_INIT_TAKE1("CacheLastModifiedFactor", set_cache_factor, NULL, RSRC_CONF,
+    AP_INIT_TAKE1("CacheLastModifiedFactor", set_cache_factor, NULL, RSRC_CONF|ACCESS_CONF,
                   "The factor used to estimate Expires date from "
                   "LastModified date"),
     AP_INIT_FLAG("CacheLock", set_cache_lock,
@@ -1465,14 +2348,30 @@ static const command_rec cache_cmds[] =
                   "temp directory."),
     AP_INIT_TAKE1("CacheLockMaxAge", set_cache_lock_maxage, NULL, RSRC_CONF,
                   "Maximum age of any thundering herd lock."),
+    AP_INIT_FLAG("CacheHeader", set_cache_x_cache, NULL, RSRC_CONF | ACCESS_CONF,
+                 "Add a X-Cache header to responses. Default is off."),
+    AP_INIT_FLAG("CacheDetailHeader", set_cache_x_cache_detail, NULL,
+                 RSRC_CONF | ACCESS_CONF,
+                 "Add a X-Cache-Detail header to responses. Default is off."),
+    AP_INIT_TAKE1("CacheKeyBaseURL", set_cache_key_base_url, NULL, RSRC_CONF,
+                  "Override the base URL of reverse proxied cache keys."),
+    AP_INIT_FLAG("CacheStaleOnError", set_cache_stale_on_error,
+                 NULL, RSRC_CONF|ACCESS_CONF,
+                 "Serve stale content on 5xx errors if present. Defaults to on."),
     {NULL}
 };
 
 static void register_hooks(apr_pool_t *p)
 {
     /* cache initializer */
+    /* cache quick handler */
+    ap_hook_quick_handler(cache_quick_handler, NULL, NULL, APR_HOOK_FIRST);
     /* cache handler */
-    ap_hook_quick_handler(cache_url_handler, NULL, NULL, APR_HOOK_FIRST);
+    ap_hook_handler(cache_handler, NULL, NULL, APR_HOOK_REALLY_FIRST);
+    /* cache status */
+    cache_hook_cache_status(cache_status, NULL, NULL, APR_HOOK_MIDDLE);
+    /* cache error handler */
+    ap_hook_insert_error_filter(cache_insert_error_filter, NULL, NULL, APR_HOOK_MIDDLE);
     /* cache filters
      * XXX The cache filters need to run right after the handlers and before
      * any other filters. Consider creating AP_FTYPE_CACHE for this purpose.
@@ -1486,9 +2385,21 @@ static void register_hooks(apr_pool_t *p)
      * to be run by subrequest
      */
     /*
+     * CACHE is placed into the filter chain at an admin specified location,
+     * and when the cache_handler is run, the CACHE filter is swapped with
+     * the CACHE_OUT filter, or CACHE_SAVE filter as appropriate. This has
+     * the effect of offering optional fine control of where the cache is
+     * inserted into the filter chain.
+     */
+    cache_filter_handle =
+        ap_register_output_filter("CACHE",
+                                  cache_filter,
+                                  NULL,
+                                  AP_FTYPE_RESOURCE);
+    /*
      * CACHE_SAVE must go into the filter chain after a possible DEFLATE
      * filter to ensure that the compressed content is stored.
-     * Incrementing filter type by 1 ensures his happens.
+     * Incrementing filter type by 1 ensures this happens.
      */
     cache_save_filter_handle =
         ap_register_output_filter("CACHE_SAVE",
@@ -1509,7 +2420,7 @@ static void register_hooks(apr_pool_t *p)
      * CACHE_OUT must go into the filter chain after a possible DEFLATE
      * filter to ensure that already compressed cache objects do not
      * get compressed again. Incrementing filter type by 1 ensures
-     * his happens.
+     * this happens.
      */
     cache_out_filter_handle =
         ap_register_output_filter("CACHE_OUT",
@@ -1538,13 +2449,23 @@ static void register_hooks(apr_pool_t *p)
     ap_hook_post_config(cache_post_config, NULL, NULL, APR_HOOK_REALLY_FIRST);
 }
 
-module AP_MODULE_DECLARE_DATA cache_module =
+AP_DECLARE_MODULE(cache) =
 {
     STANDARD20_MODULE_STUFF,
-    NULL,                   /* create per-directory config structure */
-    NULL,                   /* merge per-directory config structures */
+    create_dir_config,      /* create per-directory config structure */
+    merge_dir_config,       /* merge per-directory config structures */
     create_cache_config,    /* create per-server config structure */
     merge_cache_config,     /* merge per-server config structures */
     cache_cmds,             /* command apr_table_t */
     register_hooks
 };
+
+APR_HOOK_STRUCT(
+    APR_HOOK_LINK(cache_status)
+)
+
+APR_IMPLEMENT_EXTERNAL_HOOK_RUN_ALL(cache, CACHE, int, cache_status,
+        (cache_handle_t *h, request_rec *r,
+                apr_table_t *headers, ap_cache_status_e status,
+                const char *reason), (h, r, headers, status, reason),
+        OK, DECLINED)