Hysteria outbound: Fix UDP DATAGRAM truncation with ChromeParrot (#6788)

https://github.com/XTLS/Xray-core/pull/6788#issuecomment-5751428127

---------

Co-authored-by: LjhAUMEM <llnu14702@gmail.com>

proxy/hysteria/client.go

@@ -236,14 +236,14 @@ type UDPReader struct {
 
 func (r *UDPReader) ReadFrom(p []byte) (n int, addr *net.Destination, err error) {
 	for {
-		var buf [hysteria.MaxDatagramFrameSize]byte
+		var packet [1500]byte
 
-		n, err := r.reader.Read(buf[:])
+		n, err := r.reader.Read(packet[:])
 		if err != nil {
 			return 0, nil, err
 		}
 
-		msg, err := ParseUDPMessage(buf[:n])
+		msg, err := ParseUDPMessage(packet[:n])
 		if err != nil {
 			continue
 		}

transport/internet/hysteria/hysteria_test.go

@@ -0,0 +1,165 @@
+package hysteria
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"net"
+	"runtime"
+	"testing"
+	"time"
+
+	"github.com/apernet/quic-go"
+	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/protocol/tls/cert"
+)
+
+func TestDatagram(t *testing.T) {
+	run := func() (addr net.Addr, recv chan int64, cancel func()) {
+		cert, _ := cert.MustGenerate(nil)
+		Certificate := [][]byte{cert.Certificate}
+		PrivateKey := common.Must2(x509.ParsePKCS8PrivateKey(cert.PrivateKey))
+
+		tlsConf := &tls.Config{
+			Certificates: []tls.Certificate{
+				{
+					Certificate: Certificate,
+					PrivateKey:  PrivateKey,
+				},
+			},
+			NextProtos: []string{"h3"},
+		}
+
+		quicConf := &quic.Config{
+			InitialStreamReceiveWindow:     8388608,
+			MaxStreamReceiveWindow:         8388608,
+			InitialConnectionReceiveWindow: 8388608 * 5 / 2,
+			MaxConnectionReceiveWindow:     8388608 * 5 / 2,
+			MaxIdleTimeout:                 30 * time.Second,
+			MaxIncomingStreams:             1024,
+			DisablePathMTUDiscovery:        runtime.GOOS != "linux" && runtime.GOOS != "windows" && runtime.GOOS != "darwin",
+			EnableDatagrams:                true,
+			MaxDatagramFrameSize:           MaxDatagramFrameSize,
+			AssumePeerMaxDatagramFrameSize: MaxDatagramFrameSize,
+			DisablePathManager:             true,
+		}
+
+		pktConn := common.Must2(net.ListenPacket("udp", "127.0.0.1:0"))
+		tr := &quic.Transport{Conn: pktConn}
+		l := common.Must2(tr.Listen(tlsConf, quicConf))
+
+		recv = make(chan int64)
+		ctx, cancel := context.WithCancel(context.Background())
+
+		go func() {
+			defer pktConn.Close()
+			defer tr.Close()
+			defer l.Close()
+			defer close(recv)
+
+			var buf [1500]byte
+			for {
+				conn, err := l.Accept(ctx)
+				if err != nil {
+					if !errors.Is(err, context.Canceled) {
+						t.Error(err)
+					}
+					break
+				}
+				err = conn.SendDatagram(buf[:])
+				var qErr *quic.DatagramTooLargeError
+				if !errors.As(err, &qErr) {
+					t.Error(err)
+				}
+				recv <- qErr.MaxDatagramPayloadSize
+				defer conn.CloseWithError(0, "")
+			}
+		}()
+
+		return l.Addr(), recv, cancel
+	}
+
+	addr, recv, cancel := run()
+
+	t.Run("With ChromeParrot", func(t *testing.T) {
+		tlsConf := &tls.Config{
+			InsecureSkipVerify: true,
+		}
+
+		quicConf := &quic.Config{
+			InitialStreamReceiveWindow:     8388608,
+			MaxStreamReceiveWindow:         8388608,
+			InitialConnectionReceiveWindow: 8388608 * 5 / 2,
+			MaxConnectionReceiveWindow:     8388608 * 5 / 2,
+			MaxIdleTimeout:                 30 * time.Second,
+			KeepAlivePeriod:                10 * time.Second,
+			DisablePathMTUDiscovery:        runtime.GOOS != "linux" && runtime.GOOS != "windows" && runtime.GOOS != "darwin",
+			ChromeParrot:                   true,
+			EnableDatagrams:                true,
+			MaxDatagramFrameSize:           MaxDatagramFrameSize,
+			OmitMaxDatagramFrameSize:       true,
+			DisablePathManager:             true,
+		}
+
+		pktConn := common.Must2(net.ListenPacket("udp", "127.0.0.1:0"))
+		tr := &quic.Transport{Conn: pktConn, ConnectionIDGenerator: quic.ZeroLengthConnectionIDGenerator{}}
+		conn := common.Must2(tr.DialEarly(context.Background(), addr, tlsConf, quicConf))
+
+		defer pktConn.Close()
+		defer tr.Close()
+		defer conn.CloseWithError(0, "")
+
+		var buf [1500]byte
+		err := conn.SendDatagram(buf[:])
+		var qErr *quic.DatagramTooLargeError
+		if !errors.As(err, &qErr) || qErr.MaxDatagramPayloadSize != 1197 {
+			t.Error(err)
+		}
+		if server := <-recv; server != 1243 {
+			t.Error(server)
+		}
+	})
+
+	t.Run("Without ChromeParrot", func(t *testing.T) {
+		tlsConf := &tls.Config{
+			InsecureSkipVerify: true,
+			NextProtos:         []string{"h3"},
+		}
+
+		quicConf := &quic.Config{
+			InitialStreamReceiveWindow:     8388608,
+			MaxStreamReceiveWindow:         8388608,
+			InitialConnectionReceiveWindow: 8388608 * 5 / 2,
+			MaxConnectionReceiveWindow:     8388608 * 5 / 2,
+			MaxIdleTimeout:                 30 * time.Second,
+			KeepAlivePeriod:                10 * time.Second,
+			DisablePathMTUDiscovery:        runtime.GOOS != "linux" && runtime.GOOS != "windows" && runtime.GOOS != "darwin",
+			ChromeParrot:                   false,
+			EnableDatagrams:                true,
+			MaxDatagramFrameSize:           MaxDatagramFrameSize,
+			OmitMaxDatagramFrameSize:       true,
+			DisablePathManager:             true,
+		}
+
+		pktConn := common.Must2(net.ListenPacket("udp", "127.0.0.1:0"))
+		tr := &quic.Transport{Conn: pktConn}
+		conn := common.Must2(tr.DialEarly(context.Background(), addr, tlsConf, quicConf))
+
+		defer pktConn.Close()
+		defer tr.Close()
+		defer conn.CloseWithError(0, "")
+
+		var buf [1500]byte
+		err := conn.SendDatagram(buf[:])
+		var qErr *quic.DatagramTooLargeError
+		if !errors.As(err, &qErr) || qErr.MaxDatagramPayloadSize != 1197 {
+			t.Error(err)
+		}
+		if server := <-recv; server != 1197 {
+			t.Error(server)
+		}
+	})
+
+	cancel()
+}