add support for uot on hysteria2

docs/configuration/outbound/hysteria2.md

@@ -15,6 +15,7 @@
   },
   "password": "goofy_ahh_password",
   "network": "tcp",
+  "udp_over_stream": false,
   "tls": {},
   "brutal_debug": false,
 
@@ -72,6 +73,15 @@ One of `tcp` `udp`.
 
 Both is enabled by default.
 
+#### udp_over_stream
+
+This is the Hysteria2 port of the [UDP over TCP protocol](/configuration/shared/udp-over-tcp), designed to provide a QUIC
+stream based UDP relay mode that Hysteria2 does not provide. Since it is an add-on protocol, you will need to use sing-box or
+another program compatible with the protocol as a server.
+
+This mode can improve reliability in proxying UDP traffic in lossy networks, as it supports retransmitting lost packets using
+QUIC's loss detection mechanisms.
+
 #### tls
 
 ==Required==

inbound/hysteria2.go

@@ -4,6 +4,7 @@ package inbound
 
 import (
 	"context"
+	"github.com/sagernet/sing-box/common/uot"
 	"net"
 	"net/http"
 	"net/http/httputil"
@@ -80,7 +81,7 @@ func NewHysteria2(ctx context.Context, router adapter.Router, logger log.Context
 			protocol:      C.TypeHysteria2,
 			network:       []string{N.NetworkUDP},
 			ctx:           ctx,
-			router:        router,
+			router:        uot.NewRouter(router, logger),
 			logger:        logger,
 			tag:           tag,
 			listenOptions: options.ListenOptions,

option/hysteria2.go

@@ -25,11 +25,12 @@ type Hysteria2User struct {
 type Hysteria2OutboundOptions struct {
 	DialerOptions
 	ServerOptions
-	UpMbps      int                 `json:"up_mbps,omitempty"`
-	DownMbps    int                 `json:"down_mbps,omitempty"`
-	Obfs        *Hysteria2Obfs      `json:"obfs,omitempty"`
-	Password    string              `json:"password,omitempty"`
-	Network     NetworkList         `json:"network,omitempty"`
-	TLS         *OutboundTLSOptions `json:"tls,omitempty"`
-	BrutalDebug bool                `json:"brutal_debug,omitempty"`
+	UpMbps        int                 `json:"up_mbps,omitempty"`
+	DownMbps      int                 `json:"down_mbps,omitempty"`
+	Obfs          *Hysteria2Obfs      `json:"obfs,omitempty"`
+	Password      string              `json:"password,omitempty"`
+	Network       NetworkList         `json:"network,omitempty"`
+	TLS           *OutboundTLSOptions `json:"tls,omitempty"`
+	UDPOverStream bool                `json:"udp_over_stream,omitempty"`
+	BrutalDebug   bool                `json:"brutal_debug,omitempty"`
 }

outbound/hysteria2.go

@@ -4,6 +4,7 @@ package outbound
 
 import (
 	"context"
+	"github.com/sagernet/sing/common/uot"
 	"net"
 	"os"
 
@@ -29,7 +30,8 @@ var (
 
 type Hysteria2 struct {
 	myOutboundAdapter
-	client *hysteria2.Client
+	client    *hysteria2.Client
+	udpStream bool
 }
 
 func NewHysteria2(ctx context.Context, router adapter.Router, logger log.ContextLogger, tag string, options option.Hysteria2OutboundOptions) (*Hysteria2, error) {
@@ -83,7 +85,8 @@ func NewHysteria2(ctx context.Context, router adapter.Router, logger log.Context
 			tag:          tag,
 			dependencies: withDialerDependency(options.DialerOptions),
 		},
-		client: client,
+		client:    client,
+		udpStream: options.UDPOverStream,
 	}, nil
 }
 
@@ -93,19 +96,43 @@ func (h *Hysteria2) DialContext(ctx context.Context, network string, destination
 		h.logger.InfoContext(ctx, "outbound connection to ", destination)
 		return h.client.DialConn(ctx, destination)
 	case N.NetworkUDP:
-		conn, err := h.ListenPacket(ctx, destination)
-		if err != nil {
-			return nil, err
+		if h.udpStream {
+			h.logger.InfoContext(ctx, "outbound stream packet connection to ", destination)
+			streamConn, err := h.client.DialConn(ctx, uot.RequestDestination(uot.Version))
+			if err != nil {
+				return nil, err
+			}
+			return uot.NewLazyConn(streamConn, uot.Request{
+				IsConnect:   true,
+				Destination: destination,
+			}), nil
+		} else {
+			conn, err := h.ListenPacket(ctx, destination)
+			if err != nil {
+				return nil, err
+			}
+			return bufio.NewBindPacketConn(conn, destination), nil
 		}
-		return bufio.NewBindPacketConn(conn, destination), nil
 	default:
 		return nil, E.New("unsupported network: ", network)
 	}
 }
 
 func (h *Hysteria2) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
-	h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
-	return h.client.ListenPacket(ctx)
+	if h.udpStream {
+		h.logger.InfoContext(ctx, "outbound stream packet connection to ", destination)
+		streamConn, err := h.client.DialConn(ctx, uot.RequestDestination(uot.Version))
+		if err != nil {
+			return nil, err
+		}
+		return uot.NewLazyConn(streamConn, uot.Request{
+			IsConnect:   false,
+			Destination: destination,
+		}), nil
+	} else {
+		h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
+		return h.client.ListenPacket(ctx)
+	}
 }
 
 func (h *Hysteria2) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {