Add autest for cache_range_request, add TSCacheUrlSet check (8.1.x)

doc/admin-guide/plugins/cache_range_requests.en.rst

@@ -0,0 +1,191 @@
+.. 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:: ../../common.defs
+
+.. _admin-plugins-cache-range-requests:
+
+
+Cache Range Requests Plugin
+***************************
+
+Description
+===========
+
+Most origin servers support HTTP/1.1 range requests (rfc 7233).
+ATS internally handles range request caching in one of 2 ways:
+
+* Don't cache range requests.
+* Only server range requests from a wholly cached object.
+
+This plugin allows you to remap individual range requests so that they
+are stored as individual objects in the ATS cache when subsequent range
+requests are likely to use the same range.  This spreads range requests
+over multiple stripes thereby reducing I/O wait and system load averages.
+
+:program:`cache_range_requests` reads the range request header byte range
+value and then creates a new ``cache key URL`` using the original request
+url with the range value appended to it.  The range header is removed
+where appropriate from the requests and the origin server response code
+is changed from a 206 to a 200 to insure that the object is written to
+cache using the new cache key url.  The response code sent to the client
+will be changed back to a 206 and all requests to the origin server will
+contain the range header so that the correct response is received.
+
+The :program:`cache_range_requests` plugin by itself has no logic to
+efficiently manage overlapping ranges.  It is best to use this plugin
+in conjunction with a smart client that only requests predetermined
+non overlapping cache ranges (request blocking) or as a helper for the
+:program:`slice` plugin.
+
+Only requests which contain the ``Range: <units>=`` GET header
+will be served by the :program:`cache_range_requests` plugin.
+
+If/when ATS implements partial object caching this plugin will
+become deprecated.
+
+*NOTE* Given a multi range request the :program:`cache_range_requests`
+only processes the first range and ignores the rest.
+
+How to run the plugin
+=====================
+
+The plugin can run as a global plugin (a single global instance configured
+using :file:`plugin.config`) or as per-remap plugin (a separate instance
+configured per remap rule in :file:`remap.config`).
+
+Global instance
+---------------
+
+.. code::
+
+  $ cat plugin.config
+  cache_range_request.so
+
+
+Per-remap instance
+------------------
+
+.. code::
+
+  $cat remap.config
+  map http://www.example.com http://www.origin.com \
+      @plugin=cache_range_requests.so
+
+
+If both global and per-remap instance are used the per-remap configuration
+would take precedence (per-remap configuration would be applied and the
+global configuration ignored).
+
+Plugin options
+==============
+
+
+Parent Selection as Cache Key
+-----------------------------
+
+.. option:: --ps-cachekey
+.. option:: -p
+
+Without this option parent selection is based solely on the hash of a
+URL Path a URL is requested from the same upstream parent cache listed
+in parent.config
+
+
+With this option parent selection is based on the full ``cache key URL``
+which includes information about the partial content range.  In this mode,
+all requests (include partial content) will use consistent hashing method
+for parent selection.
+
+
+X-CRR-IMS header support
+------------------------
+
+.. option:: --consider-ims
+.. option:: -c
+
+To support slice plugin self healing an option to force revalidation
+after cache lookup complete was added.  This option is triggered by a
+special header:
+
+.. code::
+
+    X-CRR-IMS: Tue, 19 Nov 2019 13:26:45 GMT
+
+When this header is provided and a `cache hit fresh` is encoutered the
+``Date`` header of the object in cache is compared to this header date
+value.  If the cache date is *less* than this IMS date then the object
+is marked as STALE and an appropriate If-Modified-Since or If-Match
+request along with this X-CRR-IMS header is passed up to the parent.
+
+In order for this to properly work in a CDN each cache in the
+chain *SHOULD* also contain a remap rule with the
+:program:`cache_range_requests` plugin with this option set.
+
+Don't modify the Cache Key
+--------------------------
+
+.. option:: --no-modify-cachekey
+.. option:: -n
+
+With each transaction TSCacheUrlSet may only be called once.  When
+using the `cache_range_requests` plugin in conjunction with the
+`cachekey` plugin the option `--include-headers=Range` should be
+added as a `cachekey` parameter with this option.  Configuring this
+incorrectly *WILL* result in cache poisoning.
+
+.. code::
+
+       map http://ats/ http://parent/ \
+           @plugin=cachekey.so @pparam=--include-headers=Range \
+           @plugin=cache_range_requests.so @pparam=--no-modify-cachekey
+
+*Without this `cache_range_requests` plugin option*
+
+*IF* the TSCacheUrlSet call in cache_range_requests fails, an error is
+generated in the logs and the cache_range_requests plugin will disable
+transaction caching in order to avoid cache poisoning.
+
+Configuration examples
+======================
+
+Global plugin
+-------------
+
+.. code::
+
+    cache_range_requests.so --ps-cachekey --consider-ims --no-modify-cachekey
+
+or
+
+.. code::
+
+    cache_range_requests.so -p -c -n
+
+Remap plugin
+------------
+
+.. code::
+
+    map http://ats http://parent @plugin=cache_range_requests.so @pparam=--ps-cachekey @pparam=--consider-ims @pparam=--no-modify-cachekey
+
+or
+
+.. code::
+
+    map http://ats http://parent @plugin=cache_range_requests.so @pparam=-p @pparam=-c @pparam=-n

plugins/experimental/cache_range_requests/cache_range_requests.cc

@@ -26,11 +26,13 @@
  * requests.
  */
 
-#include <cstdio>
-#include <cstring>
 #include "ts/ts.h"
 #include "ts/remap.h"
 
+#include <cstdio>
+#include <cstring>
+#include <getopt.h>
+
 #define PLUGIN_NAME "cache_range_requests"
 #define DEBUG_LOG(fmt, ...) TSDebug(PLUGIN_NAME, "[%s:%d] %s(): " fmt, __FILE__, __LINE__, __func__, ##__VA_ARGS__)
 #define ERROR_LOG(fmt, ...) TSError("[%s:%d] %s(): " fmt, __FILE__, __LINE__, __func__, ##__VA_ARGS__)
@@ -41,7 +43,8 @@ typedef enum parent_select_mode {
 } parent_select_mode_t;
 
 struct pluginconfig {
-  parent_select_mode_t ps_mode;
+  parent_select_mode_t ps_mode{PS_DEFAULT};
+  bool modify_cache_key{true};
 };
 
 struct txndata {
@@ -56,7 +59,7 @@ static void handle_server_read_response(TSHttpTxn, struct txndata *);
 static int remove_header(TSMBuffer, TSMLoc, const char *, int);
 static bool set_header(TSMBuffer, TSMLoc, const char *, int, const char *, int);
 static int transaction_handler(TSCont, TSEvent, void *);
-static struct pluginconfig *create_pluginconfig(int argc, const char *argv[]);
+static struct pluginconfig *create_pluginconfig(int argc, char *const argv[]);
 static void delete_pluginconfig(struct pluginconfig *);
 
 // pluginconfig struct (global plugin only)
@@ -68,26 +71,50 @@ static struct pluginconfig *gPluginConfig = nullptr;
  * Walk plugin argument list and updates config
  */
 static struct pluginconfig *
-create_pluginconfig(int argc, const char *argv[])
+create_pluginconfig(int argc, char *const argv[])
 {
-  struct pluginconfig *pc = nullptr;
-
-  pc = (struct pluginconfig *)TSmalloc(sizeof(struct pluginconfig));
+  struct pluginconfig *pc = new pluginconfig;
 
   if (nullptr == pc) {
     ERROR_LOG("Can't allocate pluginconfig");
     return nullptr;
   }
 
-  // Plugin uses default ATS selection (hash of URL path)
-  pc->ps_mode = PS_DEFAULT;
+  static const struct option longopts[] = {
+    {const_cast<char *>("ps-cachekey"), no_argument, nullptr, 'p'},
+    {const_cast<char *>("no-modify-cachekey"), no_argument, nullptr, 'n'},
+    {nullptr, 0, nullptr, 0},
+  };
 
-  // Walk through param list.
-  for (int c = 0; c < argc; c++) {
-    if (strcmp("ps_mode:cache_key_url", argv[c]) == 0) {
-      pc->ps_mode = PS_CACHEKEY_URL;
+  // getopt assumes args start at '1'
+  ++argc;
+  --argv;
+
+  for (;;) {
+    int const opt = getopt_long(argc, argv, "", longopts, nullptr);
+    if (-1 == opt) {
       break;
     }
+
+    switch (opt) {
+    case 'p': {
+      DEBUG_LOG("Plugin modifies parent selection key");
+      pc->ps_mode = PS_CACHEKEY_URL;
+    } break;
+    case 'n': {
+      DEBUG_LOG("Plugin doesn't modify cache key");
+      pc->modify_cache_key = false;
+    } break;
+    default: {
+      DEBUG_LOG("Unknown option: '%c'", opt);
+    } break;
+    }
+  }
+
+  // Backwards compatibility
+  if (optind < argc && 0 == strcmp("ps_mode:cache_key_url", argv[optind])) {
+    DEBUG_LOG("Plugin modifies parent selection key (deprecated)");
+    pc->ps_mode = PS_CACHEKEY_URL;
   }
 
   return pc;
@@ -101,7 +128,7 @@ delete_pluginconfig(struct pluginconfig *pc)
 {
   if (nullptr != pc) {
     DEBUG_LOG("Delete struct pluginconfig");
-    TSfree(pc);
+    delete pc;
     pc = nullptr;
   }
 }
@@ -165,23 +192,29 @@ range_header_check(TSHttpTxn txnp, struct pluginconfig *pc)
             TSfree(req_url);
           }
 
-          // set the cache key.
-          if (TS_SUCCESS != TSCacheUrlSet(txnp, cache_key_url, cache_key_url_length)) {
-            DEBUG_LOG("failed to change the cache url to %s.", cache_key_url);
-          }
+          if (nullptr != pc) {
+            // set the cache key if configured to.
+            if (pc->modify_cache_key && TS_SUCCESS != TSCacheUrlSet(txnp, cache_key_url, cache_key_url_length)) {
+              ERROR_LOG("failed to change the cache url to %s.", cache_key_url);
+              ERROR_LOG("Disabling cache for this transaction to avoid cache poisoning.");
+              TSHttpTxnServerRespNoStoreSet(txnp, 1);
+              TSHttpTxnRespCacheableSet(txnp, 0);
+              TSHttpTxnReqCacheableSet(txnp, 0);
+            }
 
-          // Optionally set the parent_selection_url to the cache_key url or path
-          if (nullptr != pc && PS_DEFAULT != pc->ps_mode) {
-            TSMLoc ps_loc = nullptr;
-
-            if (PS_CACHEKEY_URL == pc->ps_mode) {
-              const char *start = cache_key_url;
-              const char *end   = cache_key_url + cache_key_url_length;
-              if (TS_SUCCESS == TSUrlCreate(hdr_bufp, &ps_loc) &&
-                  TS_PARSE_DONE == TSUrlParse(hdr_bufp, ps_loc, &start, end) && // This should always succeed.
-                  TS_SUCCESS == TSHttpTxnParentSelectionUrlSet(txnp, hdr_bufp, ps_loc)) {
-                DEBUG_LOG("Set Parent Selection URL to cache_key_url: %s", cache_key_url);
-                TSHandleMLocRelease(hdr_bufp, TS_NULL_MLOC, ps_loc);
+            // Optionally set the parent_selection_url to the cache_key url or path
+            if (PS_DEFAULT != pc->ps_mode) {
+              TSMLoc ps_loc = nullptr;
+
+              if (PS_CACHEKEY_URL == pc->ps_mode) {
+                const char *start = cache_key_url;
+                const char *end   = cache_key_url + cache_key_url_length;
+                if (TS_SUCCESS == TSUrlCreate(hdr_bufp, &ps_loc) &&
+                    TS_PARSE_DONE == TSUrlParse(hdr_bufp, ps_loc, &start, end) && // This should always succeed.
+                    TS_SUCCESS == TSHttpTxnParentSelectionUrlSet(txnp, hdr_bufp, ps_loc)) {
+                  DEBUG_LOG("Set Parent Selection URL to cache_key_url: %s", cache_key_url);
+                  TSHandleMLocRelease(hdr_bufp, TS_NULL_MLOC, ps_loc);
+                }
               }
             }
           }
@@ -411,11 +444,10 @@ TSRemapNewInstance(int argc, char *argv[], void **ih, char * /*errbuf */, int /*
   }
 
   // Skip over the Remap params
-  const char **plugin_argv = const_cast<const char **>(argv + 2);
-  argc -= 2;
+  char *const *plugin_argv = const_cast<char *const *>(argv);
 
   // Parse the argument list.
-  *ih = (struct pluginconfig *)create_pluginconfig(argc, plugin_argv);
+  *ih = (struct pluginconfig *)create_pluginconfig(argc - 2, plugin_argv + 2);
 
   if (*ih == nullptr) {
     ERROR_LOG("Can't create pluginconfig");
@@ -472,9 +504,8 @@ TSPluginInit(int argc, const char *argv[])
   if (nullptr == gPluginConfig) {
     if (argc > 1) {
       // Skip ahead of first param (name of traffic server plugin shared object)
-      const char **plugin_argv = const_cast<const char **>(argv + 1);
-      argc -= 1;
-      gPluginConfig = create_pluginconfig(argc, plugin_argv);
+      char *const *plugin_argv = const_cast<char *const *>(argv);
+      gPluginConfig            = create_pluginconfig(argc - 1, plugin_argv + 1);
     }
   }