Add support for IPV6 in dns resolvers

core/pkg/net/dns/dns.go

@@ -18,15 +18,18 @@ package dns
 
 import (
 	"io/ioutil"
+	"net"
 	"strings"
 
 	"github.com/golang/glog"
 )
 
+var defResolvConf = "/etc/resolv.conf"
+
 // GetSystemNameServers returns the list of nameservers located in the file /etc/resolv.conf
-func GetSystemNameServers() ([]string, error) {
-	var nameservers []string
-	file, err := ioutil.ReadFile("/etc/resolv.conf")
+func GetSystemNameServers() ([]net.IP, error) {
+	var nameservers []net.IP
+	file, err := ioutil.ReadFile(defResolvConf)
 	if err != nil {
 		return nameservers, err
 	}
@@ -43,10 +46,13 @@ func GetSystemNameServers() ([]string, error) {
 			continue
 		}
 		if fields[0] == "nameserver" {
-			nameservers = append(nameservers, fields[1:]...)
+			ip := net.ParseIP(fields[1])
+			if ip != nil {
+				nameservers = append(nameservers, ip)
+			}
 		}
 	}
 
-	glog.V(3).Infof("nameservers to use: %v", nameservers)
+	glog.V(3).Infof("nameservers IP address/es to use: %v", nameservers)
 	return nameservers, nil
 }

core/pkg/net/dns/dns_test.go

@@ -17,6 +17,9 @@ limitations under the License.
 package dns
 
 import (
+	"io/ioutil"
+	"net"
+	"os"
 	"testing"
 )
 
@@ -28,4 +31,31 @@ func TestGetDNSServers(t *testing.T) {
 	if len(s) < 1 {
 		t.Error("expected at least 1 nameserver in /etc/resolv.conf")
 	}
+
+	file, err := ioutil.TempFile("", "fw")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	defer file.Close()
+	defer os.Remove(file.Name())
+
+	ioutil.WriteFile(file.Name(), []byte(`
+	nameserver 2001:4860:4860::8844
+	nameserver 2001:4860:4860::8888
+	nameserver 8.8.8.8
+	`), 0644)
+
+	defResolvConf = file.Name()
+	s, err = GetSystemNameServers()
+	if err != nil {
+		t.Fatalf("unexpected error reading /etc/resolv.conf file: %v", err)
+	}
+	if len(s) < 3 {
+		t.Errorf("expected at 3 nameservers but %v returned", len(s))
+	}
+
+	eip := net.ParseIP("2001:4860:4860::8844")
+	if !s[0].Equal(eip) {
+		t.Errorf("expected %v as nameservers but %v returned", eip, s[0])
+	}
 }

core/pkg/net/net.go

@@ -0,0 +1,30 @@
+/*
+Copyright 2015 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package net
+
+import (
+	_net "net"
+	"strings"
+)
+
+// IsIPV6 checks if the input contains a valid IPV6 address
+func IsIPV6(ip _net.IP) bool {
+	if dp := strings.Index(ip.String(), ":"); dp != -1 {
+		return true
+	}
+	return false
+}

core/pkg/net/net_test.go

@@ -0,0 +1,43 @@
+/*
+Copyright 2015 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package net
+
+import (
+	"net"
+	"testing"
+)
+
+func TestIsIPV6(t *testing.T) {
+	tests := []struct {
+		in     net.IP
+		isIPV6 bool
+	}{
+		{net.ParseIP("2001:4860:4860::8844"), true},
+		{net.ParseIP("2001:4860:4860::8888"), true},
+		{net.ParseIP("0:0:0:0:0:ffff:c868:8165"), true},
+		{net.ParseIP("2001:db8:85a3::8a2e:370:7334"), true},
+		{net.ParseIP("::1"), true},
+		{net.ParseIP("8.8.8.8"), false},
+	}
+
+	for _, test := range tests {
+		isIPV6 := IsIPV6(test.in)
+		if isIPV6 && !test.isIPV6 {
+			t.Fatalf("%v expected %v but returned %v", test.in, test.isIPV6, isIPV6)
+		}
+	}
+}