cache: Do not revalidate resources that haven't expired even if must-revalidate is present

RFC2616 14.9.4

"When the must-revalidate directive is present in a response received by
a cache, that cache MUST NOT use the entry after it becomes stale to
respond to a subsequent request without first revalidating it with the origin server.
(I.e., the cache MUST do an end-to-end revalidation every time, if,
based solely on the origin server's Expires or max-age value, the cached
response is stale.)"

Update also the unit tests, since they were checking the wrong
behaviour.

https://bugzilla.gnome.org/show_bug.cgi?id=744468

2 files changed, 18 insertions, 5 deletions

diff --git a/libsoup/soup-cache.c b/libsoup/soup-cache.c
index e9538169..d118c4c0 100644
--- a/libsoup/soup-cache.c
+++ b/libsoup/soup-cache.c
@@ -1186,12 +1186,17 @@ soup_cache_has_response (SoupCache *cache, SoupMessage *msg)
 	/* 6. The stored response is either: fresh, allowed to be
 	 * served stale or succesfully validated
 	 */
-	/* TODO consider also proxy-revalidate & s-maxage */
-	if (entry->must_revalidate)
-		return SOUP_CACHE_RESPONSE_NEEDS_VALIDATION;
-
 	if (!soup_cache_entry_is_fresh_enough (entry, min_fresh)) {
 		/* Not fresh, can it be served stale? */
+
+		/* When the must-revalidate directive is present in a
+		 * response received by a cache, that cache MUST NOT
+		 * use the entry after it becomes stale
+		 */
+		/* TODO consider also proxy-revalidate & s-maxage */
+		if (entry->must_revalidate)
+			return SOUP_CACHE_RESPONSE_NEEDS_VALIDATION;
+
 		if (max_stale != -1) {
 			/* G_MAXINT32 means we accept any staleness */
 			if (max_stale == G_MAXINT32)
diff --git a/tests/cache-test.c b/tests/cache-test.c
index 543ef022..f332a3f7 100644
--- a/tests/cache-test.c
+++ b/tests/cache-test.c
@@ -288,9 +288,11 @@ do_basics_test (gconstpointer data)
 			    NULL);
 	body2 = do_request (session, base_uri, "GET", "/2", NULL,
 			    "Test-Set-Last-Modified", "Fri, 01 Jan 2010 00:00:00 GMT",
+			    "Test-Set-Cache-Control", "must-revalidate",
 			    NULL);
 	body3 = do_request (session, base_uri, "GET", "/3", NULL,
 			    "Test-Set-Last-Modified", "Fri, 01 Jan 2010 00:00:00 GMT",
+			    "Test-Set-Expires", "Sat, 02 Jan 2011 00:00:00 GMT",
 			    "Test-Set-Cache-Control", "must-revalidate",
 			    NULL);
 	body4 = do_request (session, base_uri, "GET", "/4", NULL,
@@ -316,6 +318,9 @@ do_basics_test (gconstpointer data)
 	debug_printf (1, "  Heuristically-fresh cached resource\n");
 	cmp = do_request (session, base_uri, "GET", "/2", NULL,
 			  NULL);
+	/* Not validated even if it has must-revalidate, because it hasn't expired */
+	soup_test_assert (!last_request_validated,
+			  "Request for /2 was validated");
 	soup_test_assert (!last_request_hit_network,
 			  "Request for /2 not filled from cache");
 	g_assert_cmpstr (body2, ==, cmp);
@@ -338,10 +343,11 @@ do_basics_test (gconstpointer data)
 	g_free (cmp);
 
 
-	/* Last-Modified + must-revalidate causes a conditional request */
+	/* Expired + must-revalidate causes a conditional request */
 	debug_printf (1, "  Unchanged must-revalidate resource w/ Last-Modified\n");
 	cmp = do_request (session, base_uri, "GET", "/3", NULL,
 			  "Test-Set-Last-Modified", "Fri, 01 Jan 2010 00:00:00 GMT",
+			  "Test-Set-Expires", "Sat, 02 Jan 2011 00:00:00 GMT",
 			  "Test-Set-Cache-Control", "must-revalidate",
 			  NULL);
 	soup_test_assert (last_request_validated,
@@ -356,6 +362,7 @@ do_basics_test (gconstpointer data)
 	debug_printf (1, "  Changed must-revalidate resource w/ Last-Modified\n");
 	cmp = do_request (session, base_uri, "GET", "/3", NULL,
 			  "Test-Set-Last-Modified", "Sat, 02 Jan 2010 00:00:00 GMT",
+			  "Test-Set-Expires", "Sat, 02 Jan 2011 00:00:00 GMT",
 			  "Test-Set-Cache-Control", "must-revalidate",
 			  NULL);
 	soup_test_assert (last_request_validated,
@@ -455,6 +462,7 @@ do_cancel_test (gconstpointer data)
 			    NULL);
 	body2 = do_request (session, base_uri, "GET", "/2", NULL,
 			    "Test-Set-Last-Modified", "Fri, 01 Jan 2010 00:00:00 GMT",
+			    "Test-Set-Expires", "Fri, 01 Jan 2011 00:00:00 GMT",
 			    "Test-Set-Cache-Control", "must-revalidate",
 			    NULL);