feat(netxlite): implements NS queries (#734)

This diff has been extracted from eb0bf38957.

See https://github.com/ooni/probe/issues/2096.

While there, skip the broken tests caused by issue
https://github.com/ooni/probe/issues/2098.

internal/engine/internal/sessionresolver/sessionresolver.go

@@ -29,6 +29,7 @@ import (
 	"errors"
 	"fmt"
 	"math/rand"
+	"net"
 	"net/url"
 	"sync"
 	"time"
@@ -110,9 +111,16 @@ func (r *Resolver) Stats() string {
 	return fmt.Sprintf("sessionresolver: %s", string(data))
 }
 
+var errNotImplemented = errors.New("not implemented")
+
 // LookupHTTPS implements Resolver.LookupHTTPS.
 func (r *Resolver) LookupHTTPS(ctx context.Context, domain string) (*model.HTTPSSvc, error) {
-	return nil, errors.New("not implemented")
+	return nil, errNotImplemented
+}
+
+// LookupNS implements Resolver.LookupNS.
+func (r *Resolver) LookupNS(ctx context.Context, domain string) ([]*net.NS, error) {
+	return nil, errNotImplemented
 }
 
 // ErrLookupHost indicates that LookupHost failed.

internal/engine/internal/sessionresolver/sessionresolver_test.go

@@ -343,3 +343,27 @@ func TestShouldSkipWithProxyWorks(t *testing.T) {
 		}
 	}
 }
+
+func TestUnimplementedFunctions(t *testing.T) {
+	t.Run("LookupHTTPS", func(t *testing.T) {
+		r := &Resolver{}
+		https, err := r.LookupHTTPS(context.Background(), "dns.google")
+		if !errors.Is(err, errNotImplemented) {
+			t.Fatal("unexpected error", err)
+		}
+		if https != nil {
+			t.Fatal("expected nil result")
+		}
+	})
+
+	t.Run("LookupNS", func(t *testing.T) {
+		r := &Resolver{}
+		ns, err := r.LookupNS(context.Background(), "dns.google")
+		if !errors.Is(err, errNotImplemented) {
+			t.Fatal("unexpected error", err)
+		}
+		if len(ns) > 0 {
+			t.Fatal("expected empty result")
+		}
+	})
+}