Avoid parsing retransmits we already responded to.

Decryption will fail as we already moved the IV when we sent the
response. Without this change, encrypted retransmits would have been
discarded during parsing already.

src/libcharon/sa/task_manager_v1.c

@@ -653,15 +653,46 @@ METHOD(task_manager_t, process_message, status_t,
 	host_t *me, *other;
 	status_t status;
 
+	/* TODO-IKEv1: update hosts more selectively */
+	me = msg->get_destination(msg);
+	other = msg->get_source(msg);
+	mid = msg->get_message_id(msg);
+
+	if ((mid && mid == this->initiating.mid) ||
+		(this->initiating.mid == 0 &&
+		 this->active_tasks->get_count(this->active_tasks)))
+	{
+		status = msg->parse_body(msg, this->ike_sa->get_keymat(this->ike_sa));
+		if (status != SUCCESS)
+		{
+			return status;
+		}
+		this->ike_sa->set_statistic(this->ike_sa, STAT_INBOUND,
+									time_monotonic(NULL));
+		this->ike_sa->update_hosts(this->ike_sa, me, other, TRUE);
+		charon->bus->message(charon->bus, msg, FALSE);
+		if (process_response(this, msg) != SUCCESS)
+		{
+			flush(this);
+			return DESTROY_ME;
+		}
+	}
+	else
+	{
+		hash = chunk_hash(msg->get_packet_data(msg));
+		if (hash == this->responding.hash)
+		{
+			DBG1(DBG_IKE, "received retransmit of request with ID %d, "
+				 "retransmitting response", mid);
+			charon->sender->send(charon->sender,
+						this->responding.packet->clone(this->responding.packet));
+			return SUCCESS;
+		}
 		status = msg->parse_body(msg, this->ike_sa->get_keymat(this->ike_sa));
 		if (status != SUCCESS)
 		{
 			return status;
 		}
-
-	me = msg->get_destination(msg);
-	other = msg->get_source(msg);
-
 		/* if this IKE_SA is virgin, we check for a config */
 		if (this->ike_sa->get_ike_cfg(this->ike_sa) == NULL)
 		{
@@ -686,32 +717,6 @@ METHOD(task_manager_t, process_message, status_t,
 		}
 		this->ike_sa->set_statistic(this->ike_sa, STAT_INBOUND,
 									time_monotonic(NULL));
-
-	/* TODO-IKEv1: update hosts more selectively */
-	mid = msg->get_message_id(msg);
-	if ((mid && mid == this->initiating.mid) ||
-		(this->initiating.mid == 0 &&
-		 this->active_tasks->get_count(this->active_tasks)))
-	{
-		this->ike_sa->update_hosts(this->ike_sa, me, other, TRUE);
-		charon->bus->message(charon->bus, msg, FALSE);
-		if (process_response(this, msg) != SUCCESS)
-		{
-			flush(this);
-			return DESTROY_ME;
-		}
-	}
-	else
-	{
-		hash = chunk_hash(msg->get_packet_data(msg));
-		if (hash == this->responding.hash)
-		{
-			DBG1(DBG_IKE, "received retransmit of request with ID %d, "
-				 "retransmitting response", mid);
-			charon->sender->send(charon->sender,
-						this->responding.packet->clone(this->responding.packet));
-			return SUCCESS;
-		}
 		this->ike_sa->update_hosts(this->ike_sa, me, other, TRUE);
 		charon->bus->message(charon->bus, msg, TRUE);
 		if (process_request(this, msg) != SUCCESS)