新增协议SBProxy-MC

protocol/sbproxy/java_server.go

@@ -0,0 +1,120 @@
+package sbproxy
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"encoding/json"
+	"io"
+	"net"
+
+	"github.com/sagernet/sing-box/adapter"
+	N "github.com/sagernet/sing/common/network"
+)
+
+func (h *Inbound) handleJavaConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext, onClose N.CloseHandlerFunc) {
+	_, _, err := ReadVarInt(conn) // packet len
+	if err != nil {
+		conn.Close()
+		return
+	}
+	packetID, _, err := ReadVarInt(conn)
+	if err != nil || packetID != 0x00 {
+		conn.Close()
+		return
+	}
+
+	ReadVarInt(conn) // protocol version
+	ReadString(conn) // server address
+	binary.Read(conn, binary.BigEndian, new(uint16))
+	nextState, _, _ := ReadVarInt(conn)
+
+	switch nextState {
+	case 1: // Status
+		h.handleJavaStatus(conn)
+	case 2: // Login
+		h.handleJavaLogin(ctx, conn, metadata, onClose)
+	default:
+		conn.Close()
+	}
+}
+
+func (h *Inbound) handleJavaStatus(conn net.Conn) {
+	for {
+		packetLen, _, err := ReadVarInt(conn)
+		if err != nil {
+			return
+		}
+		packetID, _, err := ReadVarInt(conn)
+		if err != nil {
+			return
+		}
+
+		if packetID == 0x00 { // Status Request
+			motd := h.options.MOTD
+			if motd == "" {
+				motd = "A Minecraft Server"
+			}
+			ver := h.options.Version
+			if ver == "" {
+				ver = "1.20.1"
+			}
+
+			resp := map[string]any{
+				"version":     map[string]any{"name": ver, "protocol": 763},
+				"players":     map[string]any{"max": h.options.MaxPlayers, "online": 0, "sample": []any{}},
+				"description": map[string]any{"text": motd},
+			}
+			data, _ := json.Marshal(resp)
+
+			var body bytes.Buffer
+			WriteVarInt(&body, 0x00) // Response ID
+			WriteString(&body, string(data))
+
+			WriteVarInt(conn, int32(body.Len()))
+			conn.Write(body.Bytes())
+		} else if packetID == 0x01 { // Ping
+			var b [8]byte
+			io.ReadFull(conn, b[:])
+
+			var body bytes.Buffer
+			WriteVarInt(&body, 0x01)
+			body.Write(b[:])
+
+			WriteVarInt(conn, int32(body.Len()))
+			conn.Write(body.Bytes())
+			return
+		} else {
+			io.CopyN(io.Discard, conn, int64(packetLen)-1)
+		}
+	}
+}
+
+func (h *Inbound) handleJavaLogin(ctx context.Context, conn net.Conn, username string, metadata adapter.InboundContext, onClose N.CloseHandlerFunc) {
+	// Note: Packet length is already read in switch or caller
+	// Login Start
+	packetLen, _, err := ReadVarInt(conn)
+	if err != nil {
+		conn.Close()
+		return
+	}
+	packetID, _, err := ReadVarInt(conn)
+	if err != nil || packetID != 0x00 {
+		conn.Close()
+		return
+	}
+	user, _ := ReadString(conn)
+
+	// Offline Mode: No encryption/auth sequence, just Login Success
+	var loginSuccess bytes.Buffer
+	WriteVarInt(&loginSuccess, 0x02) // Login Success ID
+	// UUID (offline)
+	loginSuccess.Write(make([]byte, 16))
+	WriteString(&loginSuccess, user)
+	WriteVarInt(&loginSuccess, 0) // No properties
+
+	WriteVarInt(conn, int32(loginSuccess.Len()))
+	conn.Write(loginSuccess.Bytes())
+
+	h.handlePlay(ctx, conn, user, metadata, onClose)
+}