Merging upstream version 2.4.59.

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

1 files changed, 62 insertions, 24 deletions

diff --git a/modules/http2/h2_push.h b/modules/http2/h2_push.h
index bc24e68..947b73b 100644
--- a/modules/http2/h2_push.h
+++ b/modules/http2/h2_push.h
@@ -17,10 +17,12 @@
 #ifndef __mod_h2__h2_push__
 #define __mod_h2__h2_push__
 
+#include <http_protocol.h>
+
 #include "h2.h"
+#include "h2_headers.h"
 
 struct h2_request;
-struct h2_headers;
 struct h2_ngheader;
 struct h2_session;
 struct h2_stream;
@@ -35,6 +37,44 @@ typedef enum {
     H2_PUSH_DIGEST_SHA256
 } h2_push_digest_type;
 
+/*******************************************************************************
+ * push diary 
+ *
+ * - The push diary keeps track of resources already PUSHed via HTTP/2 on this
+ *   connection. It records a hash value from the absolute URL of the resource
+ *   pushed.
+ * - Lacking openssl, 
+ * - with openssl, it uses SHA256 to calculate the hash value, otherwise it
+ *   falls back to apr_hashfunc_default()
+ * - whatever the method to generate the hash, the diary keeps a maximum of 64
+ *   bits per hash, limiting the memory consumption to about 
+ *      H2PushDiarySize * 8 
+ *   bytes. Entries are sorted by most recently used and oldest entries are
+ *   forgotten first.
+ * - While useful by itself to avoid duplicated PUSHes on the same connection,
+ *   the original idea was that clients provided a 'Cache-Digest' header with
+ *   the values of *their own* cached resources. This was described in
+ *   <https://datatracker.ietf.org/doc/draft-kazuho-h2-cache-digest/> 
+ *   and some subsequent revisions that tweaked values but kept the overall idea.
+ * - The draft was abandoned by the IETF http-wg, as support from major clients,
+ *   e.g. browsers, was lacking for various reasons.
+ * - For these reasons, mod_h2 abandoned its support for client supplied values
+ *   but keeps the diary. It seems to provide value for applications using PUSH,
+ *   is configurable in size and defaults to a very moderate amount of memory
+ *   used.
+ * - The cache digest header is a Golomb Coded Set of hash values, but it may
+ *   limit the amount of bits per hash value even further. For a good description
+ *   of GCS, read here:
+ *   <http://giovanni.bajo.it/post/47119962313/golomb-coded-sets-smaller-than-bloom-filters>
+ ******************************************************************************/
+ 
+ 
+/*
+ * The push diary is based on the abandoned draft 
+ * <https://datatracker.ietf.org/doc/draft-kazuho-h2-cache-digest/>
+ * that describes how to use golomb filters.
+ */
+
 typedef struct h2_push_diary h2_push_diary;
 
 typedef void h2_push_digest_calc(h2_push_diary *diary, apr_uint64_t *phash, h2_push *push);
@@ -59,14 +99,21 @@ struct h2_push_diary {
  * @param res the response from the server
  * @return array of h2_push addresses or NULL
  */
-apr_array_header_t *h2_push_collect(apr_pool_t *p, 
-                                    const struct h2_request *req, 
-                                    int push_policy, 
+#if AP_HAS_RESPONSE_BUCKETS
+apr_array_header_t *h2_push_collect(apr_pool_t *p,
+                                    const struct h2_request *req,
+                                    apr_uint32_t push_policy,
+                                    const ap_bucket_response *res);
+#else
+apr_array_header_t *h2_push_collect(apr_pool_t *p,
+                                    const struct h2_request *req,
+                                    apr_uint32_t push_policy,
                                     const struct h2_headers *res);
+#endif
 
 /**
  * Create a new push diary for the given maximum number of entries.
- * 
+ *
  * @param p the pool to use
  * @param N the max number of entries, rounded up to 2^x
  * @return the created diary, might be NULL of max_entries is 0
@@ -83,14 +130,21 @@ apr_array_header_t *h2_push_diary_update(struct h2_session *session, apr_array_h
  * Collect pushes for the given request/response pair, enter them into the
  * diary and return those pushes newly entered.
  */
-apr_array_header_t *h2_push_collect_update(struct h2_stream *stream, 
-                                           const struct h2_request *req, 
+#if AP_HAS_RESPONSE_BUCKETS
+apr_array_header_t *h2_push_collect_update(struct h2_stream *stream,
+                                           const struct h2_request *req,
+                                           const ap_bucket_response *res);
+#else
+apr_array_header_t *h2_push_collect_update(struct h2_stream *stream,
+                                           const struct h2_request *req,
                                            const struct h2_headers *res);
+#endif
+
 /**
  * Get a cache digest as described in 
  * https://datatracker.ietf.org/doc/draft-kazuho-h2-cache-digest/
  * from the contents of the push diary.
- * 
+ *
  * @param diary the diary to calculdate the digest from
  * @param p the pool to use
  * @param authority the authority to get the data for, use NULL/"*" for all
@@ -101,20 +155,4 @@ apr_status_t h2_push_diary_digest_get(h2_push_diary *diary, apr_pool_t *p,
                                       int maxP, const char *authority, 
                                       const char **pdata, apr_size_t *plen);
 
-/**
- * Initialize the push diary by a cache digest as described in 
- * https://datatracker.ietf.org/doc/draft-kazuho-h2-cache-digest/
- * .
- * @param diary the diary to set the digest into
- * @param authority the authority to set the data for
- * @param data the binary cache digest
- * @param len the length of the cache digest
- * @return APR_EINVAL if digest was not successfully parsed
- */
-apr_status_t h2_push_diary_digest_set(h2_push_diary *diary, const char *authority, 
-                                      const char *data, apr_size_t len);
-
-apr_status_t h2_push_diary_digest64_set(h2_push_diary *diary, const char *authority, 
-                                        const char *data64url, apr_pool_t *pool);
-
 #endif /* defined(__mod_h2__h2_push__) */