Adding upstream version 2.4.57.upstream/2.4.57

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1543 insertions, 0 deletions

diff --git a/modules/cache/mod_cache_socache.c b/modules/cache/mod_cache_socache.c
new file mode 100644
index 0000000..5f9e1d6
--- /dev/null
+++ b/modules/cache/mod_cache_socache.c
@@ -0,0 +1,1543 @@
+/* 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 "apr_lib.h"
+#include "apr_file_io.h"
+#include "apr_strings.h"
+#include "apr_buckets.h"
+
+#include "apr_version.h"
+#if !APR_VERSION_AT_LEAST(2,0,0)
+#include "apu_version.h"
+#endif
+
+#include "httpd.h"
+#include "http_config.h"
+#include "http_log.h"
+#include "http_core.h"
+#include "http_protocol.h"
+#include "ap_provider.h"
+#include "ap_socache.h"
+#include "util_filter.h"
+#include "util_script.h"
+#include "util_charset.h"
+#include "util_mutex.h"
+
+#include "mod_cache.h"
+#include "mod_status.h"
+
+#include "cache_socache_common.h"
+
+/*
+ * mod_cache_socache: Shared Object Cache Based HTTP 1.1 Cache.
+ *
+ * Flow to Find the entry:
+ *   Incoming client requests URI /foo/bar/baz
+ *   Fetch URI key (may contain Format #1 or Format #2)
+ *   If format #1 (Contains a list of Vary Headers):
+ *      Use each header name (from .header) with our request values (headers_in) to
+ *      regenerate key using HeaderName+HeaderValue+.../foo/bar/baz
+ *      re-read in key (must be format #2)
+ *
+ * Format #1:
+ *   apr_uint32_t format;
+ *   apr_time_t expire;
+ *   apr_array_t vary_headers (delimited by CRLF)
+ *
+ * Format #2:
+ *   cache_socache_info_t (first sizeof(apr_uint32_t) bytes is the format)
+ *   entity name (sobj->name) [length is in cache_socache_info_t->name_len]
+ *   r->headers_out (delimited by CRLF)
+ *   CRLF
+ *   r->headers_in (delimited by CRLF)
+ *   CRLF
+ */
+
+module AP_MODULE_DECLARE_DATA cache_socache_module;
+
+/*
+ * cache_socache_object_t
+ * Pointed to by cache_object_t::vobj
+ */
+typedef struct cache_socache_object_t
+{
+    apr_pool_t *pool; /* pool */
+    unsigned char *buffer; /* the cache buffer */
+    apr_size_t buffer_len; /* size of the buffer */
+    apr_bucket_brigade *body; /* brigade containing the body, if any */
+    apr_table_t *headers_in; /* Input headers to save */
+    apr_table_t *headers_out; /* Output headers to save */
+    cache_socache_info_t socache_info; /* Header information. */
+    apr_size_t body_offset; /* offset to the start of the body */
+    apr_off_t body_length; /* length of the cached entity body */
+    apr_time_t expire; /* when to expire the entry */
+
+    const char *name; /* Requested URI without vary bits - suitable for mortals. */
+    const char *key; /* On-disk prefix; URI with Vary bits (if present) */
+    apr_off_t offset; /* Max size to set aside */
+    apr_time_t timeout; /* Max time to set aside */
+    unsigned int newbody :1; /* whether a new body is present */
+    unsigned int done :1; /* Is the attempt to cache complete? */
+} cache_socache_object_t;
+
+/*
+ * mod_cache_socache configuration
+ */
+#define DEFAULT_MAX_FILE_SIZE 100*1024
+#define DEFAULT_MAXTIME 86400
+#define DEFAULT_MINTIME 600
+#define DEFAULT_READSIZE 0
+#define DEFAULT_READTIME 0
+
+typedef struct cache_socache_provider_conf
+{
+    const char *args;
+    ap_socache_provider_t *socache_provider;
+    ap_socache_instance_t *socache_instance;
+} cache_socache_provider_conf;
+
+typedef struct cache_socache_conf
+{
+    cache_socache_provider_conf *provider;
+} cache_socache_conf;
+
+typedef struct cache_socache_dir_conf
+{
+    apr_off_t max; /* maximum file size for cached files */
+    apr_time_t maxtime; /* maximum expiry time */
+    apr_time_t mintime; /* minimum expiry time */
+    apr_off_t readsize; /* maximum data to attempt to cache in one go */
+    apr_time_t readtime; /* maximum time taken to cache in one go */
+    unsigned int max_set :1;
+    unsigned int maxtime_set :1;
+    unsigned int mintime_set :1;
+    unsigned int readsize_set :1;
+    unsigned int readtime_set :1;
+} cache_socache_dir_conf;
+
+/* Shared object cache and mutex */
+static const char * const cache_socache_id = "cache-socache";
+static apr_global_mutex_t *socache_mutex = NULL;
+
+/*
+ * Local static functions
+ */
+
+static apr_status_t read_array(request_rec *r, apr_array_header_t *arr,
+        unsigned char *buffer, apr_size_t buffer_len, apr_size_t *slider)
+{
+    apr_size_t val = *slider;
+
+    while (*slider < buffer_len) {
+        if (buffer[*slider] == '\r') {
+            if (val == *slider) {
+                (*slider)++;
+                return APR_SUCCESS;
+            }
+            *((const char **) apr_array_push(arr)) = apr_pstrndup(r->pool,
+                    (const char *) buffer + val, *slider - val);
+            (*slider)++;
+            if (buffer[*slider] == '\n') {
+                (*slider)++;
+            }
+            val = *slider;
+        }
+        else if (buffer[*slider] == '\0') {
+            (*slider)++;
+            return APR_SUCCESS;
+        }
+        else {
+            (*slider)++;
+        }
+    }
+
+    return APR_EOF;
+}
+
+static apr_status_t store_array(apr_array_header_t *arr, unsigned char *buffer,
+        apr_size_t buffer_len, apr_size_t *slider)
+{
+    int i, len;
+    const char **elts;
+
+    elts = (const char **) arr->elts;
+
+    for (i = 0; i < arr->nelts; i++) {
+        apr_size_t e_len = strlen(elts[i]);
+        if (e_len + 3 >= buffer_len - *slider) {
+            return APR_EOF;
+        }
+        len = apr_snprintf(buffer ? (char *) buffer + *slider : NULL,
+                buffer ? buffer_len - *slider : 0, "%s" CRLF, elts[i]);
+        *slider += len;
+    }
+    if (buffer) {
+        memcpy(buffer + *slider, CRLF, sizeof(CRLF) - 1);
+    }
+    *slider += sizeof(CRLF) - 1;
+
+    return APR_SUCCESS;
+}
+
+static apr_status_t read_table(cache_handle_t *handle, request_rec *r,
+        apr_table_t *table, unsigned char *buffer, apr_size_t buffer_len,
+        apr_size_t *slider)
+{
+    apr_size_t key = *slider, colon = 0, len = 0;
+
+    while (*slider < buffer_len) {
+        if (buffer[*slider] == ':') {
+            if (!colon) {
+                colon = *slider;
+            }
+            (*slider)++;
+        }
+        else if (buffer[*slider] == '\r') {
+            len = colon;
+            if (key == *slider) {
+                (*slider)++;
+                if (buffer[*slider] == '\n') {
+                    (*slider)++;
+                }
+                return APR_SUCCESS;
+            }
+            if (!colon || buffer[colon++] != ':') {
+                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02344)
+                        "Premature end of cache headers.");
+                return APR_EGENERAL;
+            }
+            /* Do not go past the \r from above as apr_isspace('\r') is true */
+            while (apr_isspace(buffer[colon]) && (colon < *slider)) {
+                colon++;
+            }
+            apr_table_addn(table, apr_pstrmemdup(r->pool, (const char *) buffer
+                    + key, len - key), apr_pstrmemdup(r->pool,
+                    (const char *) buffer + colon, *slider - colon));
+            (*slider)++;
+            if (buffer[*slider] == '\n') {
+                (*slider)++;
+            }
+            key = *slider;
+            colon = 0;
+        }
+        else if (buffer[*slider] == '\0') {
+            (*slider)++;
+            return APR_SUCCESS;
+        }
+        else {
+            (*slider)++;
+        }
+    }
+
+    return APR_EOF;
+}
+
+static apr_status_t store_table(apr_table_t *table, unsigned char *buffer,
+        apr_size_t buffer_len, apr_size_t *slider)
+{
+    int i, len;
+    apr_table_entry_t *elts;
+
+    elts = (apr_table_entry_t *) apr_table_elts(table)->elts;
+    for (i = 0; i < apr_table_elts(table)->nelts; ++i) {
+        if (elts[i].key != NULL) {
+            apr_size_t key_len = strlen(elts[i].key);
+            apr_size_t val_len = strlen(elts[i].val);
+            if (key_len + val_len + 5 >= buffer_len - *slider) {
+                return APR_EOF;
+            }
+            len = apr_snprintf(buffer ? (char *) buffer + *slider : NULL,
+                    buffer ? buffer_len - *slider : 0, "%s: %s" CRLF,
+                    elts[i].key, elts[i].val);
+            *slider += len;
+        }
+    }
+    if (3 >= buffer_len - *slider) {
+        return APR_EOF;
+    }
+    if (buffer) {
+        memcpy(buffer + *slider, CRLF, sizeof(CRLF) - 1);
+    }
+    *slider += sizeof(CRLF) - 1;
+
+    return APR_SUCCESS;
+}
+
+static const char* regen_key(apr_pool_t *p, apr_table_t *headers,
+                             apr_array_header_t *varray, const char *oldkey,
+                             apr_size_t *newkeylen)
+{
+    struct iovec *iov;
+    int i, k;
+    int nvec;
+    const char *header;
+    const char **elts;
+
+    nvec = (varray->nelts * 2) + 1;
+    iov = apr_palloc(p, sizeof(struct iovec) * nvec);
+    elts = (const char **) varray->elts;
+
+    /* TODO:
+     *    - Handle multiple-value headers better. (sort them?)
+     *    - Handle Case in-sensitive Values better.
+     *        This isn't the end of the world, since it just lowers the cache
+     *        hit rate, but it would be nice to fix.
+     *
+     * The majority are case insenstive if they are values (encoding etc).
+     * Most of rfc2616 is case insensitive on header contents.
+     *
+     * So the better solution may be to identify headers which should be
+     * treated case-sensitive?
+     *  HTTP URI's (3.2.3) [host and scheme are insensitive]
+     *  HTTP method (5.1.1)
+     *  HTTP-date values (3.3.1)
+     *  3.7 Media Types [excerpt]
+     *     The type, subtype, and parameter attribute names are case-
+     *     insensitive. Parameter values might or might not be case-sensitive,
+     *     depending on the semantics of the parameter name.
+     *  4.20 Except [excerpt]
+     *     Comparison of expectation values is case-insensitive for unquoted
+     *     tokens (including the 100-continue token), and is case-sensitive for
+     *     quoted-string expectation-extensions.
+     */
+
+    for (i = 0, k = 0; i < varray->nelts; i++) {
+        header = apr_table_get(headers, elts[i]);
+        if (!header) {
+            header = "";
+        }
+        iov[k].iov_base = (char*) elts[i];
+        iov[k].iov_len = strlen(elts[i]);
+        k++;
+        iov[k].iov_base = (char*) header;
+        iov[k].iov_len = strlen(header);
+        k++;
+    }
+    iov[k].iov_base = (char*) oldkey;
+    iov[k].iov_len = strlen(oldkey);
+    k++;
+
+    return apr_pstrcatv(p, iov, k, newkeylen);
+}
+
+static int array_alphasort(const void *fn1, const void *fn2)
+{
+    return strcmp(*(char**) fn1, *(char**) fn2);
+}
+
+static void tokens_to_array(apr_pool_t *p, const char *data,
+        apr_array_header_t *arr)
+{
+    char *token;
+
+    while ((token = ap_get_list_item(p, &data)) != NULL) {
+        *((const char **) apr_array_push(arr)) = token;
+    }
+
+    /* Sort it so that "Vary: A, B" and "Vary: B, A" are stored the same. */
+    qsort((void *) arr->elts, arr->nelts, sizeof(char *), array_alphasort);
+}
+
+/*
+ * Hook and mod_cache callback functions
+ */
+static int create_entity(cache_handle_t *h, request_rec *r, const char *key,
+        apr_off_t len, apr_bucket_brigade *bb)
+{
+    cache_socache_dir_conf *dconf =
+            ap_get_module_config(r->per_dir_config, &cache_socache_module);
+    cache_socache_conf *conf = ap_get_module_config(r->server->module_config,
+            &cache_socache_module);
+    cache_object_t *obj;
+    cache_socache_object_t *sobj;
+    apr_size_t total;
+
+    if (conf->provider == NULL) {
+        return DECLINED;
+    }
+
+    /* we don't support caching of range requests (yet) */
+    /* TODO: but we could */
+    if (r->status == HTTP_PARTIAL_CONTENT) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02345)
+                "URL %s partial content response not cached",
+                key);
+        return DECLINED;
+    }
+
+    /*
+     * We have a chicken and egg problem. We don't know until we
+     * attempt to store_headers just how big the response will be
+     * and whether it will fit in the cache limits set. But we
+     * need to make a decision now as to whether we plan to try.
+     * If we make the wrong decision, we could prevent another
+     * cache implementation, such as cache_disk, from getting the
+     * opportunity to cache, and that would be unfortunate.
+     *
+     * In a series of tests, from cheapest to most expensive,
+     * decide whether or not to ignore this attempt to cache,
+     * with a small margin just to be sure.
+     */
+    if (len < 0) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02346)
+                "URL '%s' had no explicit size, ignoring", key);
+        return DECLINED;
+    }
+    if (len > dconf->max) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02347)
+                "URL '%s' body larger than limit, ignoring "
+                "(%" APR_OFF_T_FMT " > %" APR_OFF_T_FMT ")",
+                key, len, dconf->max);
+        return DECLINED;
+    }
+
+    /* estimate the total cached size, given current headers */
+    total = len + sizeof(cache_socache_info_t) + strlen(key);
+    if (APR_SUCCESS != store_table(r->headers_out, NULL, dconf->max, &total)
+            || APR_SUCCESS != store_table(r->headers_in, NULL, dconf->max,
+                    &total)) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02348)
+                "URL '%s' estimated headers size larger than limit, ignoring "
+                "(%" APR_SIZE_T_FMT " > %" APR_OFF_T_FMT ")",
+                key, total, dconf->max);
+        return DECLINED;
+    }
+
+    if (total >= dconf->max) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02349)
+                "URL '%s' body and headers larger than limit, ignoring "
+                "(%" APR_OFF_T_FMT " > %" APR_OFF_T_FMT ")",
+                key, len, dconf->max);
+        return DECLINED;
+    }
+
+    /* Allocate and initialize cache_object_t and cache_socache_object_t */
+    h->cache_obj = obj = apr_pcalloc(r->pool, sizeof(*obj));
+    obj->vobj = sobj = apr_pcalloc(r->pool, sizeof(*sobj));
+
+    obj->key = apr_pstrdup(r->pool, key);
+    sobj->key = obj->key;
+    sobj->name = obj->key;
+
+    return OK;
+}
+
+static apr_status_t sobj_body_pre_cleanup(void *baton)
+{
+    cache_socache_object_t *sobj = baton;
+    apr_brigade_cleanup(sobj->body);
+    sobj->body = NULL;
+    return APR_SUCCESS;
+}
+
+static int open_entity(cache_handle_t *h, request_rec *r, const char *key)
+{
+    cache_socache_dir_conf *dconf =
+            ap_get_module_config(r->per_dir_config, &cache_socache_module);
+    cache_socache_conf *conf = ap_get_module_config(r->server->module_config,
+            &cache_socache_module);
+    apr_uint32_t format;
+    apr_size_t slider;
+    unsigned int buffer_len;
+    const char *nkey;
+    apr_status_t rc;
+    cache_object_t *obj;
+    cache_info *info;
+    cache_socache_object_t *sobj;
+    apr_size_t len;
+
+    nkey = NULL;
+    h->cache_obj = NULL;
+
+    if (!conf->provider || !conf->provider->socache_instance) {
+        return DECLINED;
+    }
+
+    /* Create and init the cache object */
+    obj = apr_pcalloc(r->pool, sizeof(cache_object_t));
+    sobj = apr_pcalloc(r->pool, sizeof(cache_socache_object_t));
+
+    info = &(obj->info);
+
+    /* Create a temporary pool for the buffer, and destroy it if something
+     * goes wrong so we don't have large buffers of unused memory hanging
+     * about for the lifetime of the response.
+     */
+    apr_pool_create(&sobj->pool, r->pool);
+    apr_pool_tag(sobj->pool, "mod_cache_socache (open_entity)");
+
+    sobj->buffer = apr_palloc(sobj->pool, dconf->max);
+    sobj->buffer_len = dconf->max;
+
+    /* attempt to retrieve the cached entry */
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_lock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02350)
+                    "could not acquire lock, ignoring: %s", obj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return DECLINED;
+        }
+    }
+    buffer_len = sobj->buffer_len;
+    rc = conf->provider->socache_provider->retrieve(
+            conf->provider->socache_instance, r->server, (unsigned char *) key,
+            strlen(key), sobj->buffer, &buffer_len, r->pool);
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_unlock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02351)
+                    "could not release lock, ignoring: %s", obj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return DECLINED;
+        }
+    }
+    if (rc != APR_SUCCESS) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rc, r, APLOGNO(02352)
+                "Key not found in cache: %s", key);
+        apr_pool_destroy(sobj->pool);
+        sobj->pool = NULL;
+        return DECLINED;
+    }
+    if (buffer_len >= sobj->buffer_len) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rc, r, APLOGNO(02353)
+                "Key found in cache but too big, ignoring: %s", key);
+        apr_pool_destroy(sobj->pool);
+        sobj->pool = NULL;
+        return DECLINED;
+    }
+
+    /* read the format from the cache file */
+    memcpy(&format, sobj->buffer, sizeof(format));
+    slider = sizeof(format);
+
+    if (format == CACHE_SOCACHE_VARY_FORMAT_VERSION) {
+        apr_array_header_t* varray;
+        apr_time_t expire;
+
+        memcpy(&expire, sobj->buffer + slider, sizeof(expire));
+        slider += sizeof(expire);
+
+        varray = apr_array_make(r->pool, 5, sizeof(char*));
+        rc = read_array(r, varray, sobj->buffer, buffer_len, &slider);
+        if (rc != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r, APLOGNO(02354)
+                    "Cannot parse vary entry for key: %s", key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return DECLINED;
+        }
+
+        nkey = regen_key(r->pool, r->headers_in, varray, key, &len);
+
+        /* attempt to retrieve the cached entry */
+        if (socache_mutex) {
+            apr_status_t status = apr_global_mutex_lock(socache_mutex);
+            if (status != APR_SUCCESS) {
+                ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02355)
+                        "could not acquire lock, ignoring: %s", obj->key);
+                apr_pool_destroy(sobj->pool);
+                sobj->pool = NULL;
+                return DECLINED;
+            }
+        }
+        buffer_len = sobj->buffer_len;
+        rc = conf->provider->socache_provider->retrieve(
+                conf->provider->socache_instance, r->server,
+                (unsigned char *) nkey, len, sobj->buffer,
+                &buffer_len, r->pool);
+        if (socache_mutex) {
+            apr_status_t status = apr_global_mutex_unlock(socache_mutex);
+            if (status != APR_SUCCESS) {
+                ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02356)
+                        "could not release lock, ignoring: %s", obj->key);
+                apr_pool_destroy(sobj->pool);
+                sobj->pool = NULL;
+                return DECLINED;
+            }
+        }
+        if (rc != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rc, r, APLOGNO(02357)
+                    "Key not found in cache: %s", key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return DECLINED;
+        }
+        if (buffer_len >= sobj->buffer_len) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rc, r, APLOGNO(02358)
+                    "Key found in cache but too big, ignoring: %s", key);
+            goto fail;
+        }
+
+    }
+    else if (format != CACHE_SOCACHE_DISK_FORMAT_VERSION) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02359)
+                "Key '%s' found in cache has version %d, expected %d, ignoring",
+                key, format, CACHE_SOCACHE_DISK_FORMAT_VERSION);
+        goto fail;
+    }
+    else {
+        nkey = key;
+    }
+
+    obj->key = nkey;
+    sobj->key = nkey;
+    sobj->name = key;
+
+    if (buffer_len >= sizeof(cache_socache_info_t)) {
+        memcpy(&sobj->socache_info, sobj->buffer, sizeof(cache_socache_info_t));
+    }
+    else {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r, APLOGNO(02360)
+                "Cache entry for key '%s' too short, removing", nkey);
+        goto fail;
+    }
+    slider = sizeof(cache_socache_info_t);
+
+    /* Store it away so we can get it later. */
+    info->status = sobj->socache_info.status;
+    info->date = sobj->socache_info.date;
+    info->expire = sobj->socache_info.expire;
+    info->request_time = sobj->socache_info.request_time;
+    info->response_time = sobj->socache_info.response_time;
+
+    memcpy(&info->control, &sobj->socache_info.control, sizeof(cache_control_t));
+
+    if (sobj->socache_info.name_len <= buffer_len - slider) {
+        if (strncmp((const char *) sobj->buffer + slider, sobj->name,
+                sobj->socache_info.name_len)) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r, APLOGNO(02361)
+                    "Cache entry for key '%s' URL mismatch, ignoring", nkey);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return DECLINED;
+        }
+        slider += sobj->socache_info.name_len;
+    }
+    else {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r, APLOGNO(02362)
+                "Cache entry for key '%s' too short, removing", nkey);
+        goto fail;
+    }
+
+    /* Is this a cached HEAD request? */
+    if (sobj->socache_info.header_only && !r->header_only) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r, APLOGNO(02363)
+                "HEAD request cached, non-HEAD requested, ignoring: %s",
+                sobj->key);
+        apr_pool_destroy(sobj->pool);
+        sobj->pool = NULL;
+        return DECLINED;
+    }
+
+    h->req_hdrs = apr_table_make(r->pool, 20);
+    h->resp_hdrs = apr_table_make(r->pool, 20);
+
+    /* Call routine to read the header lines/status line */
+    if (APR_SUCCESS != read_table(h, r, h->resp_hdrs, sobj->buffer, buffer_len,
+            &slider)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r, APLOGNO(02364)
+                "Cache entry for key '%s' response headers unreadable, removing", nkey);
+        goto fail;
+    }
+    if (APR_SUCCESS != read_table(h, r, h->req_hdrs, sobj->buffer, buffer_len,
+            &slider)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r, APLOGNO(02365)
+                "Cache entry for key '%s' request headers unreadable, removing", nkey);
+        goto fail;
+    }
+
+    /* Retrieve the body if we have one */
+    len = buffer_len - slider;
+    if (len > 0) {
+        apr_bucket *e;
+        /* Create the body brigade later concatenated to the output filters'
+         * brigade by recall_body(). Since sobj->buffer (the data) point to
+         * sobj->pool (a subpool of r->pool), be safe by using a pool bucket
+         * which can morph to heap if sobj->pool is destroyed while the bucket
+         * is still alive. But if sobj->pool gets destroyed while the bucket is
+         * still in sobj->body (i.e. recall_body() was never called), we don't
+         * need to morph to something just about to be freed, so a pre_cleanup
+         * will take care of cleaning up sobj->body before this happens (and is
+         * a noop otherwise).
+         */
+        sobj->body = apr_brigade_create(sobj->pool, r->connection->bucket_alloc);
+        apr_pool_pre_cleanup_register(sobj->pool, sobj, sobj_body_pre_cleanup);
+        e = apr_bucket_pool_create((const char *) sobj->buffer + slider, len,
+                                   sobj->pool, r->connection->bucket_alloc);
+        APR_BRIGADE_INSERT_TAIL(sobj->body, e);
+    }
+
+    /* make the configuration stick */
+    h->cache_obj = obj;
+    obj->vobj = sobj;
+
+    return OK;
+
+fail:
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_lock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02366)
+                    "could not acquire lock, ignoring: %s", obj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return DECLINED;
+        }
+    }
+    conf->provider->socache_provider->remove(
+            conf->provider->socache_instance, r->server,
+            (unsigned char *) nkey, strlen(nkey), r->pool);
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_unlock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02367)
+                    "could not release lock, ignoring: %s", obj->key);
+        }
+    }
+    apr_pool_destroy(sobj->pool);
+    sobj->pool = NULL;
+    return DECLINED;
+}
+
+static int remove_entity(cache_handle_t *h)
+{
+    /* Null out the cache object pointer so next time we start from scratch  */
+    h->cache_obj = NULL;
+    return OK;
+}
+
+static int remove_url(cache_handle_t *h, request_rec *r)
+{
+    cache_socache_conf *conf = ap_get_module_config(r->server->module_config,
+            &cache_socache_module);
+    cache_socache_object_t *sobj;
+
+    sobj = (cache_socache_object_t *) h->cache_obj->vobj;
+    if (!sobj) {
+        return DECLINED;
+    }
+
+    /* Remove the key from the cache */
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_lock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02368)
+                    "could not acquire lock, ignoring: %s", sobj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return DECLINED;
+        }
+    }
+    conf->provider->socache_provider->remove(conf->provider->socache_instance,
+            r->server, (unsigned char *) sobj->key, strlen(sobj->key), r->pool);
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_unlock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02369)
+                    "could not release lock, ignoring: %s", sobj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return DECLINED;
+        }
+    }
+
+    return OK;
+}
+
+static apr_status_t recall_headers(cache_handle_t *h, request_rec *r)
+{
+    /* we recalled the headers during open_entity, so do nothing */
+    return APR_SUCCESS;
+}
+
+static apr_status_t recall_body(cache_handle_t *h, apr_pool_t *p,
+        apr_bucket_brigade *bb)
+{
+    cache_socache_object_t *sobj = (cache_socache_object_t*) h->cache_obj->vobj;
+
+    if (sobj->body) {
+        APR_BRIGADE_CONCAT(bb, sobj->body);
+    }
+
+    return APR_SUCCESS;
+}
+
+static apr_status_t store_headers(cache_handle_t *h, request_rec *r,
+        cache_info *info)
+{
+    cache_socache_dir_conf *dconf =
+            ap_get_module_config(r->per_dir_config, &cache_socache_module);
+    cache_socache_conf *conf = ap_get_module_config(r->server->module_config,
+            &cache_socache_module);
+    apr_size_t slider;
+    apr_status_t rv;
+    cache_object_t *obj = h->cache_obj;
+    cache_socache_object_t *sobj = (cache_socache_object_t*) obj->vobj;
+    cache_socache_info_t *socache_info;
+
+    memcpy(&h->cache_obj->info, info, sizeof(cache_info));
+
+    if (r->headers_out) {
+        sobj->headers_out = ap_cache_cacheable_headers_out(r);
+    }
+
+    if (r->headers_in) {
+        sobj->headers_in = ap_cache_cacheable_headers_in(r);
+    }
+
+    sobj->expire
+            = obj->info.expire > r->request_time + dconf->maxtime ? r->request_time
+                    + dconf->maxtime
+                    : obj->info.expire + dconf->mintime;
+
+    apr_pool_create(&sobj->pool, r->pool);
+    apr_pool_tag(sobj->pool, "mod_cache_socache (store_headers)");
+
+    sobj->buffer = apr_palloc(sobj->pool, dconf->max);
+    sobj->buffer_len = dconf->max;
+    socache_info = (cache_socache_info_t *) sobj->buffer;
+
+    if (sobj->headers_out) {
+        const char *vary;
+
+        vary = apr_table_get(sobj->headers_out, "Vary");
+
+        if (vary) {
+            apr_array_header_t* varray;
+            apr_uint32_t format = CACHE_SOCACHE_VARY_FORMAT_VERSION;
+
+            memcpy(sobj->buffer, &format, sizeof(format));
+            slider = sizeof(format);
+
+            memcpy(sobj->buffer + slider, &obj->info.expire,
+                    sizeof(obj->info.expire));
+            slider += sizeof(obj->info.expire);
+
+            varray = apr_array_make(r->pool, 6, sizeof(char*));
+            tokens_to_array(r->pool, vary, varray);
+
+            if (APR_SUCCESS != (rv = store_array(varray, sobj->buffer,
+                    sobj->buffer_len, &slider))) {
+                ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(02370)
+                        "buffer too small for Vary array, caching aborted: %s",
+                        obj->key);
+                apr_pool_destroy(sobj->pool);
+                sobj->pool = NULL;
+                return rv;
+            }
+            if (socache_mutex) {
+                apr_status_t status = apr_global_mutex_lock(socache_mutex);
+                if (status != APR_SUCCESS) {
+                    ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02371)
+                            "could not acquire lock, ignoring: %s", obj->key);
+                    apr_pool_destroy(sobj->pool);
+                    sobj->pool = NULL;
+                    return status;
+                }
+            }
+            rv = conf->provider->socache_provider->store(
+                    conf->provider->socache_instance, r->server,
+                    (unsigned char *) obj->key, strlen(obj->key), sobj->expire,
+                    (unsigned char *) sobj->buffer, (unsigned int) slider,
+                    sobj->pool);
+            if (socache_mutex) {
+                apr_status_t status = apr_global_mutex_unlock(socache_mutex);
+                if (status != APR_SUCCESS) {
+                    ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02372)
+                            "could not release lock, ignoring: %s", obj->key);
+                }
+            }
+            if (rv != APR_SUCCESS) {
+                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv, r, APLOGNO(02373)
+                        "Vary not written to cache, ignoring: %s", obj->key);
+                apr_pool_destroy(sobj->pool);
+                sobj->pool = NULL;
+                return rv;
+            }
+
+            obj->key = sobj->key = regen_key(r->pool, sobj->headers_in, varray,
+                                             sobj->name, NULL);
+        }
+    }
+
+    socache_info->format = CACHE_SOCACHE_DISK_FORMAT_VERSION;
+    socache_info->date = obj->info.date;
+    socache_info->expire = obj->info.expire;
+    socache_info->entity_version = sobj->socache_info.entity_version++;
+    socache_info->request_time = obj->info.request_time;
+    socache_info->response_time = obj->info.response_time;
+    socache_info->status = obj->info.status;
+
+    if (r->header_only && r->status != HTTP_NOT_MODIFIED) {
+        socache_info->header_only = 1;
+    }
+    else {
+        socache_info->header_only = sobj->socache_info.header_only;
+    }
+
+    socache_info->name_len = strlen(sobj->name);
+
+    memcpy(&socache_info->control, &obj->info.control, sizeof(cache_control_t));
+    slider = sizeof(cache_socache_info_t);
+
+    if (slider + socache_info->name_len >= sobj->buffer_len) {
+        ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(02374)
+                "cache buffer too small for name: %s",
+                sobj->name);
+        apr_pool_destroy(sobj->pool);
+        sobj->pool = NULL;
+        return APR_EGENERAL;
+    }
+    memcpy(sobj->buffer + slider, sobj->name, socache_info->name_len);
+    slider += socache_info->name_len;
+
+    if (sobj->headers_out) {
+        if (APR_SUCCESS != store_table(sobj->headers_out, sobj->buffer,
+                sobj->buffer_len, &slider)) {
+            ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(02375)
+                    "out-headers didn't fit in buffer: %s", sobj->name);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return APR_EGENERAL;
+        }
+    }
+
+    /* Parse the vary header and dump those fields from the headers_in. */
+    /* TODO: Make call to the same thing cache_select calls to crack Vary. */
+    if (sobj->headers_in) {
+        if (APR_SUCCESS != store_table(sobj->headers_in, sobj->buffer,
+                sobj->buffer_len, &slider)) {
+            ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(02376)
+                    "in-headers didn't fit in buffer %s",
+                    sobj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return APR_EGENERAL;
+        }
+    }
+
+    sobj->body_offset = slider;
+
+    return APR_SUCCESS;
+}
+
+static apr_status_t store_body(cache_handle_t *h, request_rec *r,
+        apr_bucket_brigade *in, apr_bucket_brigade *out)
+{
+    apr_bucket *e;
+    apr_status_t rv = APR_SUCCESS;
+    cache_socache_object_t *sobj =
+            (cache_socache_object_t *) h->cache_obj->vobj;
+    cache_socache_dir_conf *dconf =
+            ap_get_module_config(r->per_dir_config, &cache_socache_module);
+    int seen_eos = 0;
+
+    if (!sobj->offset) {
+        sobj->offset = dconf->readsize;
+    }
+    if (!sobj->timeout && dconf->readtime) {
+        sobj->timeout = apr_time_now() + dconf->readtime;
+    }
+
+    if (!sobj->newbody) {
+        sobj->body_length = 0;
+        sobj->newbody = 1;
+    }
+    if (sobj->offset) {
+        apr_brigade_partition(in, sobj->offset, &e);
+    }
+
+    while (APR_SUCCESS == rv && !APR_BRIGADE_EMPTY(in)) {
+        const char *str;
+        apr_size_t length;
+
+        e = APR_BRIGADE_FIRST(in);
+
+        /* are we done completely? if so, pass any trailing buckets right through */
+        if (sobj->done || !sobj->pool) {
+            APR_BUCKET_REMOVE(e);
+            APR_BRIGADE_INSERT_TAIL(out, e);
+            continue;
+        }
+
+        /* have we seen eos yet? */
+        if (APR_BUCKET_IS_EOS(e)) {
+            seen_eos = 1;
+            sobj->done = 1;
+            APR_BUCKET_REMOVE(e);
+            APR_BRIGADE_INSERT_TAIL(out, e);
+            break;
+        }
+
+        /* honour flush buckets, we'll get called again */
+        if (APR_BUCKET_IS_FLUSH(e)) {
+            APR_BUCKET_REMOVE(e);
+            APR_BRIGADE_INSERT_TAIL(out, e);
+            break;
+        }
+
+        /* metadata buckets are preserved as is */
+        if (APR_BUCKET_IS_METADATA(e)) {
+            APR_BUCKET_REMOVE(e);
+            APR_BRIGADE_INSERT_TAIL(out, e);
+            continue;
+        }
+
+        /* read the bucket, write to the cache */
+        rv = apr_bucket_read(e, &str, &length, APR_BLOCK_READ);
+        APR_BUCKET_REMOVE(e);
+        APR_BRIGADE_INSERT_TAIL(out, e);
+        if (rv != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02377)
+                    "Error when reading bucket for URL %s",
+                    h->cache_obj->key);
+            /* Remove the intermediate cache file and return non-APR_SUCCESS */
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return rv;
+        }
+
+        /* don't write empty buckets to the cache */
+        if (!length) {
+            continue;
+        }
+
+        sobj->body_length += length;
+        if (sobj->body_length >= sobj->buffer_len - sobj->body_offset) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02378)
+                    "URL %s failed the buffer size check "
+                    "(%" APR_OFF_T_FMT ">=%" APR_SIZE_T_FMT ")",
+                    h->cache_obj->key, sobj->body_length,
+                    sobj->buffer_len - sobj->body_offset);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return APR_EGENERAL;
+        }
+        memcpy(sobj->buffer + sobj->body_offset + sobj->body_length - length,
+               str, length);
+
+        /* have we reached the limit of how much we're prepared to write in one
+         * go? If so, leave, we'll get called again. This prevents us from trying
+         * to swallow too much data at once, or taking so long to write the data
+         * the client times out.
+         */
+        sobj->offset -= length;
+        if (sobj->offset <= 0) {
+            sobj->offset = 0;
+            break;
+        }
+        if ((dconf->readtime && apr_time_now() > sobj->timeout)) {
+            sobj->timeout = 0;
+            break;
+        }
+
+    }
+
+    /* Was this the final bucket? If yes, perform sanity checks.
+     */
+    if (seen_eos) {
+        const char *cl_header;
+        apr_off_t cl;
+
+        if (r->connection->aborted || r->no_cache) {
+            ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r, APLOGNO(02380)
+                    "Discarding body for URL %s "
+                    "because connection has been aborted.",
+                    h->cache_obj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return APR_EGENERAL;
+        }
+
+        cl_header = apr_table_get(r->headers_out, "Content-Length");
+        if (cl_header && (!ap_parse_strict_length(&cl, cl_header)
+                          || cl != sobj->body_length)) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02381)
+                    "URL %s didn't receive complete response, not caching",
+                    h->cache_obj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return APR_EGENERAL;
+        }
+
+        /* All checks were fine, we're good to go when the commit comes */
+
+    }
+
+    return APR_SUCCESS;
+}
+
+static apr_status_t commit_entity(cache_handle_t *h, request_rec *r)
+{
+    cache_socache_conf *conf = ap_get_module_config(r->server->module_config,
+            &cache_socache_module);
+    cache_object_t *obj = h->cache_obj;
+    cache_socache_object_t *sobj = (cache_socache_object_t *) obj->vobj;
+    apr_status_t rv;
+
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_lock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02384)
+                    "could not acquire lock, ignoring: %s", obj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return status;
+        }
+    }
+    rv = conf->provider->socache_provider->store(
+            conf->provider->socache_instance, r->server,
+            (unsigned char *) sobj->key, strlen(sobj->key), sobj->expire,
+            sobj->buffer, sobj->body_offset + sobj->body_length, sobj->pool);
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_unlock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02385)
+                    "could not release lock, ignoring: %s", obj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return status;
+        }
+    }
+    if (rv != APR_SUCCESS) {
+        ap_log_rerror(APLOG_MARK, APLOG_WARNING, rv, r, APLOGNO(02386)
+                "could not write to cache, ignoring: %s", sobj->key);
+        goto fail;
+    }
+
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02387)
+            "commit_entity: Headers and body for URL %s cached for maximum of %d seconds.",
+            sobj->name, (apr_uint32_t)apr_time_sec(sobj->expire - r->request_time));
+
+    apr_pool_destroy(sobj->pool);
+    sobj->pool = NULL;
+
+    return APR_SUCCESS;
+
+fail:
+    /* For safety, remove any existing entry on failure, just in case it could not
+     * be revalidated successfully.
+     */
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_lock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02388)
+                    "could not acquire lock, ignoring: %s", obj->key);
+            apr_pool_destroy(sobj->pool);
+            sobj->pool = NULL;
+            return rv;
+        }
+    }
+    conf->provider->socache_provider->remove(conf->provider->socache_instance,
+            r->server, (unsigned char *) sobj->key, strlen(sobj->key), r->pool);
+    if (socache_mutex) {
+        apr_status_t status = apr_global_mutex_unlock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02389)
+                    "could not release lock, ignoring: %s", obj->key);
+        }
+    }
+
+    apr_pool_destroy(sobj->pool);
+    sobj->pool = NULL;
+    return rv;
+}
+
+static apr_status_t invalidate_entity(cache_handle_t *h, request_rec *r)
+{
+    /* mark the entity as invalidated */
+    h->cache_obj->info.control.invalidated = 1;
+
+    return commit_entity(h, r);
+}
+
+static void *create_dir_config(apr_pool_t *p, char *dummy)
+{
+    cache_socache_dir_conf *dconf =
+            apr_pcalloc(p, sizeof(cache_socache_dir_conf));
+
+    dconf->max = DEFAULT_MAX_FILE_SIZE;
+    dconf->maxtime = apr_time_from_sec(DEFAULT_MAXTIME);
+    dconf->mintime = apr_time_from_sec(DEFAULT_MINTIME);
+    dconf->readsize = DEFAULT_READSIZE;
+    dconf->readtime = DEFAULT_READTIME;
+
+    return dconf;
+}
+
+static void *merge_dir_config(apr_pool_t *p, void *basev, void *addv)
+{
+    cache_socache_dir_conf
+            *new =
+                    (cache_socache_dir_conf *) apr_pcalloc(p, sizeof(cache_socache_dir_conf));
+    cache_socache_dir_conf *add = (cache_socache_dir_conf *) addv;
+    cache_socache_dir_conf *base = (cache_socache_dir_conf *) basev;
+
+    new->max = (add->max_set == 0) ? base->max : add->max;
+    new->max_set = add->max_set || base->max_set;
+    new->maxtime = (add->maxtime_set == 0) ? base->maxtime : add->maxtime;
+    new->maxtime_set = add->maxtime_set || base->maxtime_set;
+    new->mintime = (add->mintime_set == 0) ? base->mintime : add->mintime;
+    new->mintime_set = add->mintime_set || base->mintime_set;
+    new->readsize = (add->readsize_set == 0) ? base->readsize : add->readsize;
+    new->readsize_set = add->readsize_set || base->readsize_set;
+    new->readtime = (add->readtime_set == 0) ? base->readtime : add->readtime;
+    new->readtime_set = add->readtime_set || base->readtime_set;
+
+    return new;
+}
+
+static void *create_config(apr_pool_t *p, server_rec *s)
+{
+    cache_socache_conf *conf = apr_pcalloc(p, sizeof(cache_socache_conf));
+
+    return conf;
+}
+
+static void *merge_config(apr_pool_t *p, void *basev, void *overridesv)
+{
+    cache_socache_conf *ps;
+    cache_socache_conf *base = (cache_socache_conf *) basev;
+    cache_socache_conf *overrides = (cache_socache_conf *) overridesv;
+
+    /* socache server config only has one field */
+    ps = overrides ? overrides : base;
+
+    return ps;
+}
+
+/*
+ * mod_cache_socache configuration directives handlers.
+ */
+static const char *set_cache_socache(cmd_parms *cmd, void *in_struct_ptr,
+        const char *arg)
+{
+    cache_socache_conf *conf = ap_get_module_config(cmd->server->module_config,
+            &cache_socache_module);
+    cache_socache_provider_conf *provider = conf->provider
+            = apr_pcalloc(cmd->pool, sizeof(cache_socache_provider_conf));
+
+    const char *err = NULL, *sep, *name;
+
+    /* Argument is of form 'name:args' or just 'name'. */
+    sep = ap_strchr_c(arg, ':');
+    if (sep) {
+        name = apr_pstrmemdup(cmd->pool, arg, sep - arg);
+        sep++;
+        provider->args = sep;
+    }
+    else {
+        name = arg;
+    }
+
+    provider->socache_provider = ap_lookup_provider(AP_SOCACHE_PROVIDER_GROUP,
+            name, AP_SOCACHE_PROVIDER_VERSION);
+    if (provider->socache_provider == NULL) {
+        err = apr_psprintf(cmd->pool,
+                    "Unknown socache provider '%s'. Maybe you need "
+                    "to load the appropriate socache module "
+                    "(mod_socache_%s?)", name, name);
+    }
+    return err;
+}
+
+static const char *set_cache_max(cmd_parms *parms, void *in_struct_ptr,
+        const char *arg)
+{
+    cache_socache_dir_conf *dconf = (cache_socache_dir_conf *) in_struct_ptr;
+
+    if (apr_strtoff(&dconf->max, arg, NULL, 10) != APR_SUCCESS
+            || dconf->max < 1024 || dconf->max > APR_UINT32_MAX) {
+        return "CacheSocacheMaxSize argument must be a integer representing "
+               "the max size of a cached entry (headers and body), at least 1024 "
+               "and at most " APR_STRINGIFY(APR_UINT32_MAX);
+    }
+    dconf->max_set = 1;
+    return NULL;
+}
+
+static const char *set_cache_maxtime(cmd_parms *parms, void *in_struct_ptr,
+        const char *arg)
+{
+    cache_socache_dir_conf *dconf = (cache_socache_dir_conf *) in_struct_ptr;
+    apr_off_t seconds;
+
+    if (apr_strtoff(&seconds, arg, NULL, 10) != APR_SUCCESS || seconds < 0) {
+        return "CacheSocacheMaxTime argument must be the maximum amount of time in seconds to cache an entry.";
+    }
+    dconf->maxtime = apr_time_from_sec(seconds);
+    dconf->maxtime_set = 1;
+    return NULL;
+}
+
+static const char *set_cache_mintime(cmd_parms *parms, void *in_struct_ptr,
+        const char *arg)
+{
+    cache_socache_dir_conf *dconf = (cache_socache_dir_conf *) in_struct_ptr;
+    apr_off_t seconds;
+
+    if (apr_strtoff(&seconds, arg, NULL, 10) != APR_SUCCESS || seconds < 0) {
+        return "CacheSocacheMinTime argument must be the minimum amount of time in seconds to cache an entry.";
+    }
+    dconf->mintime = apr_time_from_sec(seconds);
+    dconf->mintime_set = 1;
+    return NULL;
+}
+
+static const char *set_cache_readsize(cmd_parms *parms, void *in_struct_ptr,
+        const char *arg)
+{
+    cache_socache_dir_conf *dconf = (cache_socache_dir_conf *) in_struct_ptr;
+
+    if (apr_strtoff(&dconf->readsize, arg, NULL, 10) != APR_SUCCESS
+            || dconf->readsize < 0) {
+        return "CacheSocacheReadSize argument must be a non-negative integer representing the max amount of data to cache in go.";
+    }
+    dconf->readsize_set = 1;
+    return NULL;
+}
+
+static const char *set_cache_readtime(cmd_parms *parms, void *in_struct_ptr,
+        const char *arg)
+{
+    cache_socache_dir_conf *dconf = (cache_socache_dir_conf *) in_struct_ptr;
+    apr_off_t milliseconds;
+
+    if (apr_strtoff(&milliseconds, arg, NULL, 10) != APR_SUCCESS
+            || milliseconds < 0) {
+        return "CacheSocacheReadTime argument must be a non-negative integer representing the max amount of time taken to cache in go.";
+    }
+    dconf->readtime = apr_time_from_msec(milliseconds);
+    dconf->readtime_set = 1;
+    return NULL;
+}
+
+static apr_status_t remove_lock(void *data)
+{
+    if (socache_mutex) {
+        apr_global_mutex_destroy(socache_mutex);
+        socache_mutex = NULL;
+    }
+    return APR_SUCCESS;
+}
+
+static apr_status_t destroy_cache(void *data)
+{
+    server_rec *s = data;
+    cache_socache_conf *conf =
+            ap_get_module_config(s->module_config, &cache_socache_module);
+    if (conf->provider && conf->provider->socache_instance) {
+        conf->provider->socache_provider->destroy(
+                conf->provider->socache_instance, s);
+        conf->provider->socache_instance = NULL;
+    }
+    return APR_SUCCESS;
+}
+
+static int socache_status_hook(request_rec *r, int flags)
+{
+    apr_status_t status = APR_SUCCESS;
+    cache_socache_conf *conf = ap_get_module_config(r->server->module_config,
+                                                    &cache_socache_module);
+    if (!conf->provider || !conf->provider->socache_provider ||
+        !conf->provider->socache_instance) {
+        return DECLINED;
+    }
+
+    if (!(flags & AP_STATUS_SHORT)) {
+        ap_rputs("<hr>\n"
+                 "<table cellspacing=0 cellpadding=0>\n"
+                 "<tr><td bgcolor=\"#000000\">\n"
+                 "<b><font color=\"#ffffff\" face=\"Arial,Helvetica\">"
+                 "mod_cache_socache Status:</font></b>\n"
+                 "</td></tr>\n"
+                 "<tr><td bgcolor=\"#ffffff\">\n", r);
+    }
+    else {
+        ap_rputs("ModCacheSocacheStatus\n", r);
+    }
+
+    if (socache_mutex) {
+        status = apr_global_mutex_lock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02816)
+                    "could not acquire lock for cache status");
+        }
+    }
+
+    if (status != APR_SUCCESS) {
+        if (!(flags & AP_STATUS_SHORT)) {
+            ap_rputs("No cache status data available\n", r);
+        }
+        else {
+            ap_rputs("NotAvailable\n", r);
+        }
+    } else {
+        conf->provider->socache_provider->status(conf->provider->socache_instance,
+                                                 r, flags);
+    }
+
+    if (socache_mutex && status == APR_SUCCESS) {
+        status = apr_global_mutex_unlock(socache_mutex);
+        if (status != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(02817)
+                    "could not release lock for cache status");
+        }
+    }
+
+    if (!(flags & AP_STATUS_SHORT)) {
+        ap_rputs("</td></tr>\n</table>\n", r);
+    }
+    return OK;
+}
+
+static void socache_status_register(apr_pool_t *p)
+{
+    APR_OPTIONAL_HOOK(ap, status_hook, socache_status_hook, NULL, NULL, APR_HOOK_MIDDLE);
+}
+
+static int socache_precfg(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptmp)
+{
+    apr_status_t rv = ap_mutex_register(pconf, cache_socache_id, NULL,
+            APR_LOCK_DEFAULT, 0);
+    if (rv != APR_SUCCESS) {
+        ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, plog, APLOGNO(02390)
+                "failed to register %s mutex", cache_socache_id);
+        return 500; /* An HTTP status would be a misnomer! */
+    }
+
+    /* Register to handle mod_status status page generation */
+    socache_status_register(pconf);
+
+    return OK;
+}
+
+static int socache_post_config(apr_pool_t *pconf, apr_pool_t *plog,
+        apr_pool_t *ptmp, server_rec *base_server)
+{
+    server_rec *s;
+    apr_status_t rv;
+    const char *errmsg;
+    static struct ap_socache_hints socache_hints =
+    { 64, 2048, 60000000 };
+
+    for (s = base_server; s; s = s->next) {
+        cache_socache_conf *conf =
+                ap_get_module_config(s->module_config, &cache_socache_module);
+
+        if (!conf->provider) {
+            continue;
+        }
+
+        if (!socache_mutex && conf->provider->socache_provider->flags
+                & AP_SOCACHE_FLAG_NOTMPSAFE) {
+
+            rv = ap_global_mutex_create(&socache_mutex, NULL, cache_socache_id,
+                    NULL, s, pconf, 0);
+            if (rv != APR_SUCCESS) {
+                ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, plog, APLOGNO(02391)
+                        "failed to create %s mutex", cache_socache_id);
+                return 500; /* An HTTP status would be a misnomer! */
+            }
+            apr_pool_cleanup_register(pconf, NULL, remove_lock,
+                    apr_pool_cleanup_null);
+        }
+
+        errmsg = conf->provider->socache_provider->create(
+                &conf->provider->socache_instance, conf->provider->args, ptmp,
+                pconf);
+        if (errmsg) {
+            ap_log_perror(APLOG_MARK, APLOG_CRIT, 0, plog,
+                    APLOGNO(02392) "%s", errmsg);
+            return 500; /* An HTTP status would be a misnomer! */
+        }
+
+        rv = conf->provider->socache_provider->init(
+                conf->provider->socache_instance, cache_socache_id,
+                &socache_hints, s, pconf);
+        if (rv != APR_SUCCESS) {
+            ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, plog, APLOGNO(02393)
+                    "failed to initialise %s cache", cache_socache_id);
+            return 500; /* An HTTP status would be a misnomer! */
+        }
+        apr_pool_cleanup_register(pconf, (void *) s, destroy_cache,
+                apr_pool_cleanup_null);
+
+    }
+
+    return OK;
+}
+
+static void socache_child_init(apr_pool_t *p, server_rec *s)
+{
+    const char *lock;
+    apr_status_t rv;
+    if (!socache_mutex) {
+        return; /* don't waste the overhead of creating mutex & cache */
+    }
+    lock = apr_global_mutex_lockfile(socache_mutex);
+    rv = apr_global_mutex_child_init(&socache_mutex, lock, p);
+    if (rv != APR_SUCCESS) {
+        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s, APLOGNO(02394)
+                "failed to initialise mutex in child_init");
+    }
+}
+
+static const command_rec cache_socache_cmds[] =
+{
+    AP_INIT_TAKE1("CacheSocache", set_cache_socache, NULL, RSRC_CONF,
+            "The shared object cache to store cache files"),
+    AP_INIT_TAKE1("CacheSocacheMaxTime", set_cache_maxtime, NULL, RSRC_CONF | ACCESS_CONF,
+            "The maximum cache expiry age to cache a document in seconds"),
+    AP_INIT_TAKE1("CacheSocacheMinTime", set_cache_mintime, NULL, RSRC_CONF | ACCESS_CONF,
+            "The minimum cache expiry age to cache a document in seconds"),
+    AP_INIT_TAKE1("CacheSocacheMaxSize", set_cache_max, NULL, RSRC_CONF | ACCESS_CONF,
+            "The maximum cache entry size (headers and body) to cache a document"),
+    AP_INIT_TAKE1("CacheSocacheReadSize", set_cache_readsize, NULL, RSRC_CONF | ACCESS_CONF,
+            "The maximum quantity of data to attempt to read and cache in one go"),
+    AP_INIT_TAKE1("CacheSocacheReadTime", set_cache_readtime, NULL, RSRC_CONF | ACCESS_CONF,
+            "The maximum time taken to attempt to read and cache in go"),
+    { NULL }
+};
+
+static const cache_provider cache_socache_provider =
+{
+    &remove_entity, &store_headers, &store_body, &recall_headers, &recall_body,
+    &create_entity, &open_entity, &remove_url, &commit_entity,
+    &invalidate_entity
+};
+
+static void cache_socache_register_hook(apr_pool_t *p)
+{
+    /* cache initializer */
+    ap_register_provider(p, CACHE_PROVIDER_GROUP, "socache", "0",
+            &cache_socache_provider);
+    ap_hook_pre_config(socache_precfg, NULL, NULL, APR_HOOK_MIDDLE);
+    ap_hook_post_config(socache_post_config, NULL, NULL, APR_HOOK_MIDDLE);
+    ap_hook_child_init(socache_child_init, NULL, NULL, APR_HOOK_MIDDLE);
+}
+
+AP_DECLARE_MODULE(cache_socache) = { STANDARD20_MODULE_STUFF,
+    create_dir_config,  /* create per-directory config structure */
+    merge_dir_config, /* merge per-directory config structures */
+    create_config, /* create per-server config structure */
+    merge_config, /* merge per-server config structures */
+    cache_socache_cmds, /* command apr_table_t */
+    cache_socache_register_hook /* register hooks */
+};