[libsoup] cache: Do not add Age header to all responses

[Carlos Garcia Campos <carlosgc src gnome org>]

commit 824a60e614bb7ea57f59c09b819a8f1dcb2f5b11
Author: Carlos Garcia Campos <cgarcia igalia com>
Date:   Thu Dec 4 12:38:49 2014 +0100

    cache: Do not add Age header to all responses
    
    I think we were doing this because RFC 2616 says:
    
    "When a response is generated from a cache entry, the cache MUST include a single Age
    header field in the response with a value equal to the cache entry's current_age."
    
    But it also says:
    
    "The presence of an Age header field in a response implies that a
    response is not first-hand. However, the converse is not true, since
    the lack of an Age header field in a response does not imply that the
    response is first-hand unless all caches along the request path are
    compliant with HTTP/1.1"
    
    We are always adding the Age header, even for responses sent after a
    revalidation, in which case the response is first-hand. So at least
    after a revalidation we should not include the Age header. However,
    other browsers don't seem to include the Age header in any case, and the
    first quote from RFC 2616 is not present in RFC 7234. So, the safest
    approach that is compatible with other browsers and RFC compliant is to
    never include the Age header manually in cache responses.
    
    This avoids unnecessary conditional requests made when a resource is
    considered expired because of the Age header added after a revalidation.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=741108

 libsoup/soup-cache.c |    8 --------
 1 files changed, 0 insertions(+), 8 deletions(-)
---
diff --git a/libsoup/soup-cache.c b/libsoup/soup-cache.c
index 533a175..6272dcb 100644
--- a/libsoup/soup-cache.c
+++ b/libsoup/soup-cache.c
@@ -670,7 +670,6 @@ GInputStream *
 soup_cache_send_response (SoupCache *cache, SoupMessage *msg)
 {
        SoupCacheEntry *entry;
-       char *current_age;
        GInputStream *file_stream, *body_stream, *cache_stream;
        GFile *file;
 
@@ -704,13 +703,6 @@ soup_cache_send_response (SoupCache *cache, SoupMessage *msg)
        /* Headers */
        copy_end_to_end_headers (entry->headers, msg->response_headers);
 
-       /* Add 'Age' header with the current age */
-       current_age = g_strdup_printf ("%d", soup_cache_entry_get_current_age (entry));
-       soup_message_headers_replace (msg->response_headers,
-                                     "Age",
-                                     current_age);
-       g_free (current_age);
-
        /* Create the cache stream. */
        soup_message_disable_feature (msg, SOUP_TYPE_CACHE);
        cache_stream = soup_message_setup_body_istream (body_stream, msg,