mod_cache: Don't add cached/revalidated entity headers to a 304 response.

           PR 55547.

When the conditional request meets the conditions of the stale then revalidated
entry, the forwarded 304 response includes the entity headers merged from the
cached headers (before updating the entry).
Strip them before returning a 304.

Since the entity headers are stripped elsewhere, factorize the code using a
new table (MOD_CACHE_ENTITY_HEADERS[]) containing these headers's names.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1591312 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index 9a1b0c0ce482e640116a11f1d014ddc6234649d0..0eafe9dc38b49800b40e55f34e63a6e3a6a9b448 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,9 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.0
 
+  *) mod_cache: Don't add cached/revalidated entity headers to a 304 response.
+                PR 55547. [Yann Ylavic]
+
   *) mod_cache: Retry unconditional request with the full URL (including the
      query-string) when the origin server's 304 response does not match the
      conditions used to revalidate the stale entry.  [Yann Ylavic].

diff --git a/modules/cache/mod_cache.c b/modules/cache/mod_cache.c
index af8889a8921cac8d6323af90f1820a44dd6f0ea3..a6a50ea989b8c877040467f18abbad71108cb452 100644 (file)
--- a/modules/cache/mod_cache.c
+++ b/modules/cache/mod_cache.c
@@ -36,6 +36,22 @@ static ap_filter_rec_t *cache_out_subreq_filter_handle;
 static ap_filter_rec_t *cache_remove_url_filter_handle;
 static ap_filter_rec_t *cache_invalidate_filter_handle;
 
+/**
+ * Entity headers' names
+ */
+static const char *MOD_CACHE_ENTITY_HEADERS[] = {
+    "Allow",
+    "Content-Encoding",
+    "Content-Language",
+    "Content-Length",
+    "Content-Location",
+    "Content-MD5",
+    "Content-Range",
+    "Content-Type",
+    "Last-Modified",
+    NULL
+};
+
 /*
  * CACHE handler
  * -------------
@@ -802,7 +818,7 @@ static apr_status_t cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
     apr_time_t exp, date, lastmod, now;
     apr_off_t size = -1;
     cache_info *info = NULL;
-    const char *reason;
+    const char *reason, **eh;
     apr_pool_t *p;
     apr_bucket *e;
     apr_table_t *headers;
@@ -1150,14 +1166,9 @@ static apr_status_t cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
      * inconsistencies between cached entity-bodies and updated headers.
      */
     if (r->status == HTTP_NOT_MODIFIED) {
-        apr_table_unset(r->headers_out, "Allow");
-        apr_table_unset(r->headers_out, "Content-Encoding");
-        apr_table_unset(r->headers_out, "Content-Language");
-        apr_table_unset(r->headers_out, "Content-Length");
-        apr_table_unset(r->headers_out, "Content-MD5");
-        apr_table_unset(r->headers_out, "Content-Range");
-        apr_table_unset(r->headers_out, "Content-Type");
-        apr_table_unset(r->headers_out, "Last-Modified");
+        for (eh = MOD_CACHE_ENTITY_HEADERS; *eh; ++eh) {
+            apr_table_unset(r->headers_out, *eh);
+        }
     }
 
     /* Hold the phone. Some servers might allow us to cache a 2xx, but
@@ -1441,10 +1452,14 @@ static apr_status_t cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
          * 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.
+         * err_headers_out (note that store_headers() below already selects
+         * the cacheable only headers using ap_cache_cacheable_headers_out(),
+         * here we want to keep the original headers in r->headers_out and
+         * forward all of them to the client, including non-cacheable ones).
          */
-        r->headers_out = ap_cache_cacheable_headers_out(r);
+        r->headers_out = apr_table_overlay(r->pool, r->headers_out,
+                                           r->err_headers_out);
+        apr_table_clear(r->err_headers_out);
 
         /* Merge in our cached headers.  However, keep any updated values. */
         /* take output, overlay on top of cached */
@@ -1494,6 +1509,13 @@ static apr_status_t cache_save_filter(ap_filter_t *f, apr_bucket_brigade *in)
         if (status != OK) {
             r->status = status;
 
+            /* Strip the entity headers merged from the cached headers before
+             * updating the entry (see cache_accept_headers() above).
+             */
+            for (eh = MOD_CACHE_ENTITY_HEADERS; *eh; ++eh) {
+                apr_table_unset(r->headers_out, *eh);
+            }
+
             bkt = apr_bucket_flush_create(bb->bucket_alloc);
             APR_BRIGADE_INSERT_TAIL(bb, bkt);
         }