dns: add function to get list of system name servers

3 files changed, 58 insertions, 0 deletions

diff --git a/lib/dns/funcs.go b/lib/dns/funcs.go
new file mode 100644
index 00000000..e2ab2468
--- /dev/null
+++ b/lib/dns/funcs.go
@@ -0,0 +1,26 @@
+// Copyright 2019, Shulhan <ms@kilabit.info>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package dns
+
+import (
+	libnet "github.com/shuLhan/share/lib/net"
+)
+
+//
+// GetSystemNameServers return list of system name servers by reading
+// resolv.conf formatted file in path.
+//
+// Default path is "/etc/resolv.conf".
+//
+func GetSystemNameServers(path string) []string {
+	if len(path) == 0 {
+		path = "/etc/resolv.conf"
+	}
+	rc, err := libnet.NewResolvConf(path)
+	if err != nil {
+		return nil
+	}
+	return rc.NameServers
+}
diff --git a/lib/dns/funcs_test.go b/lib/dns/funcs_test.go
new file mode 100644
index 00000000..fb9e2946
--- /dev/null
+++ b/lib/dns/funcs_test.go
@@ -0,0 +1,31 @@
+// Copyright 2019, Shulhan <ms@kilabit.info>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package dns
+
+import (
+	"testing"
+
+	"github.com/shuLhan/share/lib/test"
+)
+
+func TestGetSystemNameServers(t *testing.T) {
+	cases := []struct {
+		path string
+		exp  []string
+	}{{
+		path: "testdata/resolv.conf",
+		exp: []string{
+			"127.0.0.1",
+		},
+	}}
+
+	for _, c := range cases {
+		t.Log(c.path)
+
+		got := GetSystemNameServers(c.path)
+
+		test.Assert(t, "NameServers", c.exp, got, true)
+	}
+}
diff --git a/lib/dns/testdata/resolv.conf b/lib/dns/testdata/resolv.conf
new file mode 100644
index 00000000..bbc8559c
--- /dev/null
+++ b/lib/dns/testdata/resolv.conf
@@ -0,0 +1 @@
+nameserver 127.0.0.1