pan: add unit tests for DNS resolver

Author: FR4NK-W

pkg/pan/dns_txt_test.go

@@ -0,0 +1,75 @@
+// Copyright 2022 ETH Zurich
+//
+// 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 pan
+
+import (
+	"context"
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDNSResolver(t *testing.T) {
+	cases := []struct {
+		name      string
+		assertErr assert.ErrorAssertionFunc
+		expected  scionAddr
+	}{
+		{"example.com", assert.NoError, mustParse("1-ff00:0:f00,[192.0.2.1]")},
+		{"example.net", assert.NoError, mustParse("1-ff00:0:ba5,[192.0.2.1]")},
+		{"dummy4", assertErrHostNotFound, scionAddr{}},
+		{"barbaz", assertErrHostNotFound, scionAddr{}},
+	}
+	var m *mockResolver
+	resolver := &dnsResolver{res: m}
+	for _, c := range cases {
+		actual, err := resolver.Resolve(context.TODO(), c.name)
+		if !c.assertErr(t, err) {
+			continue
+		}
+		assert.Equal(t, c.expected, actual)
+	}
+}
+
+func TestDNSResolverInvalid(t *testing.T) {
+	r := &dnsResolver{res: nil}
+	_, err := r.Resolve(context.TODO(), "example.com")
+	assert.Error(t, err)
+}
+
+type mockResolver struct {
+	net.Resolver
+}
+
+// LookupTXT mocks requesting the DNS TXT records for the given domain name.
+func (r *mockResolver) LookupTXT(ctx context.Context, name string) ([]string, error) {
+	v, ok := map[string][]string{
+		"example.com.": {
+			"NS=ns74430548",
+			"doodle-site-verification=t4SRCkhsSDk_Ec9BPAr4xWQvYqoYJSLuoMmWLBdKqS0",
+			"scion=1-ff00:0:f00,[192.0.2.1]",
+		},
+		"example.net.": {
+			"scion=1-ff00:0:ba5,[192.0.2.1]",
+			"BOOM_verify_3ovqPKkST76TzF2c7b13YA",
+			"v=spf1 include:_id.example.net ip4:192.0.2.38 ip4:192.0.2.197 ~all",
+		},
+	}[name]
+	if !ok {
+		return nil, &net.DNSError{IsNotFound: true}
+	}
+	return v, nil
+}