vendor-ed skydns

vendor/github.com/skynetservices/skydns/server/exchange.go

@@ -0,0 +1,34 @@
+// Copyright (c) 2014 The SkyDNS Authors. All rights reserved.
+// Use of this source code is governed by The MIT License (MIT) that can be
+// found in the LICENSE file.
+
+package server
+
+import "github.com/miekg/dns"
+
+// exchangeMsg returns a new dns message based on name, type, bufsize and dnssec.
+func newExchangeMsg(name string, typ, bufsize uint16, dnssec bool) *dns.Msg {
+	m := new(dns.Msg)
+	m.SetQuestion(name, typ)
+	m.SetEdns0(bufsize, dnssec)
+	return m
+}
+
+// exchangeWithRetry sends message m to server, but retries on ServerFailure.
+func exchangeWithRetry(c *dns.Client, m *dns.Msg, server string) (*dns.Msg, error) {
+	r, _, err := c.Exchange(m, server)
+	if err == nil && r.Rcode == dns.RcodeServerFailure {
+		// redo the query
+		r, _, err = c.Exchange(m, server)
+	}
+	return r, err
+}
+
+func (s *server) randomNameserverID(id uint16) int {
+	nsid := 0
+	if s.config.NSRotate {
+		// Use request Id for "random" nameserver selection.
+		nsid = int(id) % len(s.config.Nameservers)
+	}
+	return nsid
+}