diff --git a/src/or/directory.c b/src/or/directory.c
index b680b134a4..6ce739b4f6 100644
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -3883,6 +3883,30 @@ find_best_compression_method(unsigned compression_methods, int stream)
return NO_METHOD;
}
+/** Check if any of the digests in digests matches the latest consensus
+ * flavor (given in flavor) that we have available. */
+static int
+digest_list_contains_best_consensus(consensus_flavor_t flavor,
+ const smartlist_t *digests)
+{
+ const networkstatus_t *ns = NULL;
+
+ if (digests == NULL)
+ return 0;
+
+ ns = networkstatus_get_latest_consensus_by_flavor(flavor);
+
+ if (ns == NULL)
+ return 0;
+
+ SMARTLIST_FOREACH_BEGIN(digests, const uint8_t *, digest) {
+ if (tor_memeq(ns->digest_sha3_as_signed, digest, DIGEST256_LEN))
+ return 1;
+ } SMARTLIST_FOREACH_END(digest);
+
+ return 0;
+}
+
/** Check if the given compression method is allowed for a connection that is
* supposed to be anonymous. Returns 1 if the compression method is allowed,
* otherwise 0. */
@@ -4052,6 +4076,13 @@ handle_get_current_consensus(dir_connection_t *conn,
goto done;
}
+ if (digest_list_contains_best_consensus(req.flav,
+ req.diff_from_digests)) {
+ write_http_status_line(conn, 304, "Not modified");
+ geoip_note_ns_response(GEOIP_REJECT_NOT_MODIFIED);
+ goto done;
+ }
+
struct consensus_cache_entry_t *cached_consensus = NULL;
compress_method_t compression_used = NO_METHOD;