- 1.2.1 feature: negative caching for failed queries.

	  Queries that failed are cached for 5 seconds (NORR_TTL).
	  If the failure is local, like out of memory, it is not cached.
	- the TTL comparison for the cache used different comparisons,
	  causing many cache responses that used the iterator and validator
	  state machines unnecessarily.

git-svn-id: file:///svn/unbound/trunk@1432 be551aaa-1e26-0410-a405-d3ace91eadb9

diff --git a/daemon/worker.c b/daemon/worker.c
index 4a81af94f35f0f6539223a0e631ba4ef0a734617..7635a858b5e3c085a11f3f0d9047e651484c4ee8 100644 (file)
--- a/daemon/worker.c
+++ b/daemon/worker.c
@@ -537,7 +537,7 @@ answer_from_cache(struct worker* worker, struct query_info* qinfo,
        int secure;
        int must_validate = !(flags&BIT_CD) && worker->env.need_to_validate;
        /* see if it is possible */
-       if(rep->ttl <= timenow) {
+       if(rep->ttl < timenow) {
                /* the rrsets may have been updated in the meantime.
                 * we will refetch the message format from the
                 * authoritative server 

diff --git a/doc/Changelog b/doc/Changelog
index ac9c8a97cd60e5d04364bb4bd1b8138f638762da..032f3bdd855a06a69ad250eece8550100f440a13 100644 (file)
--- a/doc/Changelog
+++ b/doc/Changelog
@@ -1,3 +1,11 @@
+14 January 2009: Wouter
+       - 1.2.1 feature: negative caching for failed queries.
+         Queries that failed are cached for 5 seconds (NORR_TTL).
+         If the failure is local, like out of memory, it is not cached.
+       - the TTL comparison for the cache used different comparisons,
+         causing many cache responses that used the iterator and validator
+         state machines unnecessarily.
+
 13 January 2009: Wouter
        - fixed bug in lameness marking, removed printouts.
        - find NS rrset more cleanly for qtype NS.

diff --git a/iterator/iterator.c b/iterator/iterator.c
index fdf3ebe3ad897d31cbf46cf6db2f8382f09f91b7..89bb90fa9788b4bb13fb45f4cab8153b6920278d 100644 (file)
--- a/iterator/iterator.c
+++ b/iterator/iterator.c
@@ -229,6 +229,34 @@ error_response(struct module_qstate* qstate, int id, int rcode)
        return 0;
 }
 
+/**
+ * Return an error to the client and cache the error code in the
+ * message cache (so per qname, qtype, qclass).
+ * @param qstate: our query state
+ * @param id: module id
+ * @param rcode: error code (DNS errcode).
+ * @return: 0 for use by caller, to make notation easy, like:
+ *     return error_response(..). 
+ */
+static int
+error_response_cache(struct module_qstate* qstate, int id, int rcode)
+{
+       /* store in cache */
+       struct reply_info err;
+       memset(&err, 0, sizeof(err));
+       err.flags = BIT_QR | BIT_RA;
+       FLAGS_SET_RCODE(err.flags, rcode);
+       err.qdcount = 1;
+       err.ttl = NORR_TTL;
+       /* do not waste time trying to validate this servfail */
+       err.security = sec_status_indeterminate;
+       verbose(VERB_ALGO, "store error response in message cache");
+       if(!iter_dns_store(qstate->env, &qstate->qinfo, &err, 0)) {
+               log_err("error_response_cache: could not store error (nomem)");
+       }
+       return error_response(qstate, id, rcode);
+}
+
 /** check if prepend item is duplicate item */
 static int
 prepend_is_duplicate(struct ub_packed_rrset_key** sets, size_t to,
@@ -1308,7 +1336,7 @@ processQueryTargets(struct module_qstate* qstate, struct iter_qstate* iq,
                                        "returning SERVFAIL");
                                /* fail -- no more targets, no more hope 
                                 * of targets, no hope of a response. */
-                               return error_response(qstate, id,
+                               return error_response_cache(qstate, id,
                                        LDNS_RCODE_SERVFAIL);
                        }
                }