From: Marek Vavruša <marek.vavrusa@nic.cz>
Date: Sat, 18 Apr 2015 21:42:15 +0000 (+0200)
Subject: lib: basic nameserver election
X-Git-Tag: v1.0.0-beta1~237^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=140e028c5c7da5abf6a8dfbb406700f802e24542;p=thirdparty%2Fknot-resolver.git

lib: basic nameserver election

nameservers with addresses are preferred, the rest
has same weight

no blacklisting, penalization or rtt scoring yet
---

diff --git a/lib/nsrep.c b/lib/nsrep.c
index e49e53124..02f9bf9af 100644
--- a/lib/nsrep.c
+++ b/lib/nsrep.c
@@ -15,9 +15,61 @@
  */
 
 #include "lib/nsrep.h"
+#include "lib/generic/pack.h"
 
-int kr_nsrep_score(const knot_dname_t *ns, struct kr_layer_param *param)
+/** @internal Macro to set address structure. */
+#define ADDR_SET(sa, family, addr, len) do {\
+    	memcpy(&sa ## _addr, (addr), (len)); \
+    	sa ## _family = (family); \
+	sa ## _port = htons(KR_DNS_PORT); \
+} while (0)
+
+/** Update nameserver representation with current name/address pair. */
+static void update_nsrep(struct kr_nsrep *ns, const knot_dname_t *name, uint8_t *addr, unsigned score)
+{
+	ns->name = name;
+	ns->score = score;
+	if (addr == NULL) {
+		return;
+	}
+
+	size_t len = pack_obj_len(addr);
+	void *addr_val = pack_obj_val(addr);
+	switch(len) {
+	case sizeof(struct in_addr):
+		ADDR_SET(ns->addr.ip4.sin, AF_INET, addr_val, len); break;
+	case sizeof(struct in6_addr):
+		ADDR_SET(ns->addr.ip6.sin6, AF_INET6, addr_val, len); break;
+	default: assert(0); break;
+	}
+}
+
+#undef ADDR_SET
+
+static int eval_nsrep(const char *k, void *v, void *baton)
+{
+	unsigned score = KR_NS_VALID;
+	struct kr_nsrep *ns = baton;
+	pack_t *addr_set = v;
+	uint8_t *addr = NULL;
+
+	/* Name server is better candidate if it has address record. */
+	if (addr_set->len > 0) {
+		addr = pack_head(*addr_set);
+		score += 1;
+	}
+
+	/* Update best scoring nameserver. */
+	if (ns->score < score) {
+		update_nsrep(ns, (const knot_dname_t *)k, addr, score);
+	}
+
+	return kr_ok();
+}
+
+int kr_nsrep_elect(struct kr_nsrep *ns, map_t *nsset)
 {
-	/* TODO: stub, always returns valid */
-	return KR_NS_VALID;
+	ns->addr.ip.sa_family = AF_UNSPEC;
+	ns->score = KR_NS_INVALID;
+	return map_walk(nsset, eval_nsrep, ns);
 }
diff --git a/lib/nsrep.h b/lib/nsrep.h
index 922912a8d..e61f063f2 100644
--- a/lib/nsrep.h
+++ b/lib/nsrep.h
@@ -20,18 +20,40 @@
 
 #pragma once
 
+#include <netinet/in.h>
+
+#include "lib/generic/map.h"
 #include "lib/layer.h"
 
 enum kr_ns_score {
-    KR_NS_INVALID = -1,
-    KR_NS_VALID   = 0
+	KR_NS_INVALID = 0,
+	KR_NS_VALID   = 1
+};
+
+struct kr_nsrep
+{
+	unsigned score;
+	const knot_dname_t *name;
+	union {
+		struct sockaddr ip;
+		struct sockaddr_in ip4;
+		struct sockaddr_in6 ip6;
+	} addr;
 };
 
-/** Return name server score (KR_NS_VALID is baseline, the higher the better).
- * @param ns evaluated NS name
- * @param param layer parameters
- * @return enum kr_ns_score or higher positive value
+/** @internal Address bytes for given family. */
+#define kr_nsrep_inaddr(addr) \
+	((addr).ip.sa_family == AF_INET ? (void *)&((addr).ip4.sin_addr) : (void *)&((addr).ip6.sin6_addr))
+/** @internal Address length for given family. */
+#define kr_nsrep_inaddr_len(addr) \
+	((addr).ip.sa_family == AF_INET ? sizeof(struct in_addr) : sizeof(struct in6_addr))
+
+/**
+ * Elect best nameserver/address pair from the nsset.
+ * @param  ns    updated NS representation
+ * @param  nsset NS set to choose from
+ * @return       0 if success (ns is updated), error otherwise
  */
-int kr_nsrep_score(const knot_dname_t *ns, struct kr_layer_param *param);
+int kr_nsrep_elect(struct kr_nsrep *ns, map_t *nsset);
 
 /** @} */
diff --git a/lib/resolve.c b/lib/resolve.c
index 3f76aa61f..47d84133a 100644
--- a/lib/resolve.c
+++ b/lib/resolve.c
@@ -70,10 +70,17 @@ static int iterate(struct knot_requestor *requestor, struct kr_layer_param *para
 	DEBUG_MSG("query '%s %s'\n", name_str, type_str);
 #endif
 
-	/* Invalid address for current zone cut. */
-	if (sockaddr_len((struct sockaddr *)&cur->zone_cut.addr) < 1) {
-		DEBUG_MSG("=> ns missing A/AAAA, fetching\n");
-		return ns_resolve_addr(cur, param);
+	/* Elect best nameserver candidate. */
+	kr_nsrep_elect(&cur->ns, &cur->zone_cut.nsset);
+	if (cur->ns.score < KR_NS_VALID) {
+		DEBUG_MSG("=> no valid NS left\n");
+		kr_rplan_pop(param->rplan, cur);
+		return KNOT_EOK;
+	} else {
+		if (cur->ns.addr.ip.sa_family == AF_UNSPEC) {
+			DEBUG_MSG("=> ns missing A/AAAA, fetching\n");
+			return ns_resolve_addr(cur, param);
+		}
 	}
 
 	/* Prepare query resolution. */
@@ -120,7 +127,7 @@ static void prepare_layers(struct knot_requestor *req, struct kr_layer_param *pa
 
 static int resolve_iterative(struct kr_layer_param *param, mm_ctx_t *pool)
 {
-	/* Initialize requestor. */
+/* Initialize requestor. */
 	struct knot_requestor requestor;
 	knot_requestor_init(&requestor, pool);
 	prepare_layers(&requestor, param);
@@ -143,6 +150,7 @@ static int resolve_iterative(struct kr_layer_param *param, mm_ctx_t *pool)
 		}
 	}
 
+	DEBUG_MSG("finished: %s, mempool: %llu B\n", knot_strerror(ret), mp_total_size(pool->ctx));
 	knot_requestor_clear(&requestor);
 	return ret;
 }