test(dns): add tests against local http:// DoH resolver

Author: aschmahmann

gateway/dns_test.go

@@ -0,0 +1,119 @@
+package gateway
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/miekg/dns"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAddNewDNSResolver(t *testing.T) {
+	ctx := context.Background()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer l.Close()
+
+	dnslinkName := "dnslink-test.foobar"
+	dnslinkValue := "/ipfs/bafkqaaa"
+
+	go func() {
+		_ = http.Serve(l, http.HandlerFunc(dnslinkServerHandlerFunc(t, dnslinkName, dnslinkValue)))
+	}()
+
+	listenAddr := l.Addr().(*net.TCPAddr)
+	r, err := NewDNSResolver(map[string]string{
+		"foobar.": fmt.Sprintf("http://%s:%d", listenAddr.IP, listenAddr.Port),
+	})
+	require.NoError(t, err)
+
+	res, err := r.LookupTXT(ctx, fmt.Sprintf("_dnslink.%s.", dnslinkName))
+	require.NoError(t, err)
+	require.Len(t, res, 1)
+	require.Equal(t, dnslinkValue, res[0])
+}
+
+func TestOverrideDNSDefaults(t *testing.T) {
+	ctx := context.Background()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer l.Close()
+
+	dnslinkName := "dnslink-test.eth"
+	dnslinkValue := "/ipfs/bafkqaaa"
+
+	go func() {
+		_ = http.Serve(l, http.HandlerFunc(dnslinkServerHandlerFunc(t, dnslinkName, dnslinkValue)))
+	}()
+
+	listenAddr := l.Addr().(*net.TCPAddr)
+	r, err := NewDNSResolver(map[string]string{
+		"eth.": fmt.Sprintf("http://%s:%d", listenAddr.IP, listenAddr.Port),
+	})
+	require.NoError(t, err)
+
+	res, err := r.LookupTXT(ctx, fmt.Sprintf("_dnslink.%s.", dnslinkName))
+	require.NoError(t, err)
+	require.Len(t, res, 1)
+	require.Equal(t, dnslinkValue, res[0])
+}
+
+func dnslinkServerHandlerFunc(t *testing.T, dnslinkName string, txtResponse string) func(w http.ResponseWriter, req *http.Request) {
+	return func(w http.ResponseWriter, req *http.Request) {
+		b, err := io.ReadAll(req.Body)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		msg := &dns.Msg{}
+		err = msg.Unpack(b)
+		require.NoError(t, err)
+		var answers []dns.RR
+		for _, q := range msg.Question {
+			if strings.ToLower(q.Name) != fmt.Sprintf("_dnslink.%s.", dnslinkName) || q.Qtype != dns.TypeTXT {
+				answers = append(answers, &dns.RR_Header{
+					Name:   q.Name,
+					Rrtype: dns.RcodeServerFailure,
+					Class:  q.Qclass,
+					Ttl:    0,
+				})
+			} else {
+				answers = append(answers, &dns.TXT{
+					Hdr: dns.RR_Header{
+						Name:   q.Name,
+						Rrtype: dns.TypeTXT,
+						Class:  dns.ClassINET,
+						Ttl:    uint32(3600),
+					},
+					Txt: []string{txtResponse},
+				})
+			}
+		}
+		var m dns.Msg
+		m.SetReply(msg)
+		m.Authoritative = true
+		m.Answer = answers
+		encoded, err := m.Pack()
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		w.Header().Set("Content-Type", "application/dns-message")
+		w.WriteHeader(http.StatusOK)
+		if _, err := w.Write(encoded); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+}