1 files changed, 149 insertions, 0 deletions
diff --git a/internal/resolver/resolver_test.go b/internal/resolver/resolver_test.go
new file mode 100644
index 0000000..0bd0402
--- /dev/null
+++ b/internal/resolver/resolver_test.go
@@ -0,0 +1,149 @@
+package resolver
+
+import (
+	"context"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/miekg/dns"
+)
+
+func startTestServer(t *testing.T, addr string, handler dns.Handler) *dns.Server {
+	t.Helper()
+	srv := &dns.Server{
+		Addr:    addr,
+		Net:     "udp",
+		Handler: handler,
+		UDPSize: 4096,
+	}
+	go func() {
+		if err := srv.ListenAndServe(); err != nil {
+		}
+	}()
+	return srv
+}
+
+func TestLookupDirectAnswer(t *testing.T) {
+	mux := dns.NewServeMux()
+	mux.HandleFunc(".", func(w dns.ResponseWriter, req *dns.Msg) {
+		resp := new(dns.Msg)
+		resp.SetReply(req)
+		resp.Authoritative = true
+		if req.Question[0].Name == "example.com." &&
+			req.Question[0].Qtype == dns.TypeA {
+			resp.Answer = append(resp.Answer, &dns.A{
+				Hdr: dns.RR_Header{
+					Name:   "example.com.",
+					Rrtype: dns.TypeA,
+					Class:  dns.ClassINET,
+					Ttl:    60,
+				},
+				A: net.IPv4(127, 0, 0, 1),
+			})
+		} else {
+			resp.Rcode = dns.RcodeNameError
+		}
+		w.WriteMsg(resp)
+	})
+
+	srv := startTestServer(t, "127.0.0.1:15353", mux)
+	defer srv.Shutdown()
+	time.Sleep(50 * time.Millisecond)
+
+	r := New(
+		WithRootAddresses([]string{"127.0.0.1:15353"}),
+		WithTimeout(500*time.Millisecond),
+	)
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	resp, err := r.Lookup(ctx, "example.com.", dns.TypeA)
+	if err != nil {
+		t.Fatalf("Lookup failed: %v", err)
+	}
+	if resp.Rcode != dns.RcodeSuccess {
+		t.Fatalf("expected NOERROR, got %d (%s)",
+			resp.Rcode, dns.RcodeToString[resp.Rcode])
+	}
+	if len(resp.Answer) != 1 {
+		t.Fatalf("expected 1 answer, got %d", len(resp.Answer))
+	}
+	a, ok := resp.Answer[0].(*dns.A)
+	if !ok {
+		t.Fatal("expected A record")
+	}
+	if !a.A.Equal(net.IPv4(127, 0, 0, 1)) {
+		t.Fatalf("expected 127.0.0.1, got %s", a.A)
+	}
+}
+
+func TestLookupNXDOMAIN(t *testing.T) {
+	mux := dns.NewServeMux()
+	mux.HandleFunc(".", func(w dns.ResponseWriter, req *dns.Msg) {
+		resp := new(dns.Msg)
+		resp.SetReply(req)
+		resp.Rcode = dns.RcodeNameError
+		w.WriteMsg(resp)
+	})
+
+	srv := startTestServer(t, "127.0.0.1:15354", mux)
+	defer srv.Shutdown()
+	time.Sleep(50 * time.Millisecond)
+
+	r := New(
+		WithRootAddresses([]string{"127.0.0.1:15354"}),
+		WithTimeout(500*time.Millisecond),
+	)
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	resp, err := r.Lookup(ctx, "nonexistent.xyz.", dns.TypeA)
+	if err != nil {
+		t.Fatalf("Lookup failed: %v", err)
+	}
+	if resp.Rcode != dns.RcodeNameError {
+		t.Fatalf("expected NXDOMAIN, got %d", resp.Rcode)
+	}
+}
+
+func TestNextServersWithGlue(t *testing.T) {
+	msg := new(dns.Msg)
+	msg.Authoritative = false
+	msg.Ns = append(msg.Ns, &dns.NS{
+		Hdr: dns.RR_Header{Name: "example.com.", Rrtype: dns.TypeNS, Ttl: 300},
+		Ns:  "ns1.example.com.",
+	})
+	msg.Extra = append(msg.Extra, &dns.A{
+		Hdr: dns.RR_Header{Name: "ns1.example.com.", Rrtype: dns.TypeA, Ttl: 300},
+		A:   net.ParseIP("192.0.2.1").To4(),
+	})
+	msg.Extra = append(msg.Extra, &dns.AAAA{
+		Hdr:  dns.RR_Header{Name: "ns1.example.com.", Rrtype: dns.TypeAAAA, Ttl: 300},
+		AAAA: net.ParseIP("2001:db8::1"),
+	})
+
+	r := &Resolver{}
+	addrs, err := r.nextServers(context.Background(), msg)
+	if err != nil {
+		t.Fatalf("nextServers failed: %v", err)
+	}
+	if len(addrs) != 1 || addrs[0] != "192.0.2.1" {
+		t.Fatalf("expected [192.0.2.1], got %v", addrs)
+	}
+}
+
+func TestNextServersNoGlue(t *testing.T) {
+	msg := new(dns.Msg)
+	msg.Authoritative = false
+	msg.Ns = append(msg.Ns, &dns.NS{
+		Hdr: dns.RR_Header{Name: "example.com.", Rrtype: dns.TypeNS, Ttl: 300},
+		Ns:  "ns1.example.com.",
+	})
+
+	r := &Resolver{maxDelegations: 30, timeout: time.Second, retries: 1}
+	_, err := r.nextServers(context.Background(), msg)
+	if err == nil {
+		t.Fatal("expected error when no glue and no roots")
+	}
+}