TUN-5590: QUIC datagram max user payload is 1217 bytes

quic/datagram_test.go

@@ -1,10 +1,20 @@
 package quic
 
 import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/pem"
+	"math/big"
 	"testing"
 
 	"github.com/google/uuid"
+	"github.com/lucas-clemente/quic-go"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/sync/errgroup"
 )
 
 var (
@@ -39,3 +49,91 @@ func TestSuffixSessionIDError(t *testing.T) {
 	_, err = SuffixSessionID(testSessionID, msg)
 	require.Error(t, err)
 }
+
+func TestMaxDatagramPayload(t *testing.T) {
+	payload := make([]byte, MaxDatagramFrameSize-sessionIDLen)
+
+	quicConfig := &quic.Config{
+		KeepAlive:       true,
+		EnableDatagrams: true,
+	}
+	quicListener := newQUICListener(t, quicConfig)
+	defer quicListener.Close()
+
+	errGroup, ctx := errgroup.WithContext(context.Background())
+	// Run edge side of datagram muxer
+	errGroup.Go(func() error {
+		// Accept quic connection
+		quicSession, err := quicListener.Accept(ctx)
+		require.NoError(t, err)
+
+		muxer, err := NewDatagramMuxer(quicSession)
+		require.NoError(t, err)
+
+		sessionID, receivedPayload, err := muxer.ReceiveFrom()
+		require.NoError(t, err)
+		require.Equal(t, testSessionID, sessionID)
+		require.True(t, bytes.Equal(payload, receivedPayload))
+
+		return nil
+	})
+
+	// Run cloudflared side of datagram muxer
+	errGroup.Go(func() error {
+		tlsClientConfig := &tls.Config{
+			InsecureSkipVerify: true,
+			NextProtos:         []string{"argotunnel"},
+		}
+		// Establish quic connection
+		quicSession, err := quic.DialAddrEarly(quicListener.Addr().String(), tlsClientConfig, quicConfig)
+		require.NoError(t, err)
+
+		muxer, err := NewDatagramMuxer(quicSession)
+		require.NoError(t, err)
+
+		err = muxer.SendTo(testSessionID, payload)
+		require.NoError(t, err)
+
+		// Payload larger than transport MTU, should return an error
+		largePayload := append(payload, byte(1))
+		err = muxer.SendTo(testSessionID, largePayload)
+		require.Error(t, err)
+
+		return nil
+	})
+
+	require.NoError(t, errGroup.Wait())
+}
+
+func newQUICListener(t *testing.T, config *quic.Config) quic.Listener {
+	// Create a simple tls config.
+	tlsConfig := generateTLSConfig()
+
+	listener, err := quic.ListenAddr("127.0.0.1:0", tlsConfig, config)
+	require.NoError(t, err)
+
+	return listener
+}
+
+func generateTLSConfig() *tls.Config {
+	key, err := rsa.GenerateKey(rand.Reader, 1024)
+	if err != nil {
+		panic(err)
+	}
+	template := x509.Certificate{SerialNumber: big.NewInt(1)}
+	certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &key.PublicKey, key)
+	if err != nil {
+		panic(err)
+	}
+	keyPEM := pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(key)})
+	certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER})
+
+	tlsCert, err := tls.X509KeyPair(certPEM, keyPEM)
+	if err != nil {
+		panic(err)
+	}
+	return &tls.Config{
+		Certificates: []tls.Certificate{tlsCert},
+		NextProtos:   []string{"argotunnel"},
+	}
+}