Rename cmd -> examples

examples/simpleServer/main.go

@@ -0,0 +1,164 @@
+// Example minecraft 1.15.2 server
+package main
+
+import (
+	"github.com/Tnze/go-mc/net"
+	pk "github.com/Tnze/go-mc/net/packet"
+	"github.com/Tnze/go-mc/offline"
+	"github.com/google/uuid"
+	"log"
+)
+
+const ProtocolVersion = 578
+const MaxPlayer = 200
+
+// Packet IDs
+const (
+	PlayerPositionAndLookClientbound = 0x36
+	JoinGame                         = 0x26
+)
+
+func main() {
+	l, err := net.ListenMC(":25565")
+	if err != nil {
+		log.Fatalf("Listen error: %v", err)
+	}
+
+	for {
+		conn, err := l.Accept()
+		if err != nil {
+			log.Fatalf("Accept error: %v", err)
+		}
+		go acceptConn(conn)
+	}
+}
+
+func acceptConn(conn net.Conn) {
+	defer conn.Close()
+	// handshake
+	protocol, intention, err := handshake(conn)
+	if err != nil {
+		log.Printf("Handshake error: %v", err)
+		return
+	}
+
+	switch intention {
+	default: //unknown error
+		log.Printf("Unknown handshake intention: %v", intention)
+	case 1: //for status
+		acceptListPing(conn)
+	case 2: //for login
+		handlePlaying(conn, protocol)
+	}
+}
+
+func handlePlaying(conn net.Conn, protocol int32) {
+	// login, get player info
+	info, err := acceptLogin(conn)
+	if err != nil {
+		log.Print("Login failed")
+		return
+	}
+
+	// Write LoginSuccess packet
+
+	if err = loginSuccess(conn, info.Name, info.UUID); err != nil {
+		log.Print("Login failed on success")
+		return
+	}
+
+	if err := joinGame(conn); err != nil {
+		log.Print("Login failed on joinGame")
+		return
+	}
+	if err := conn.WritePacket(pk.Marshal(PlayerPositionAndLookClientbound,
+		// https://wiki.vg/index.php?title=Protocol&oldid=16067#Player_Position_And_Look_.28clientbound.29
+		pk.Double(0), pk.Double(0), pk.Double(0), // XYZ
+		pk.Float(0), pk.Float(0), // Yaw Pitch
+		pk.Byte(0),   // flag
+		pk.VarInt(0), // TP ID
+	)); err != nil {
+		log.Print("Login failed on sending PlayerPositionAndLookClientbound")
+		return
+	}
+	// Just for block this goroutine. Keep the connection
+	for {
+		var p pk.Packet
+		if err := conn.ReadPacket(&p); err != nil {
+			log.Printf("ReadPacket error: %v", err)
+			break
+		}
+		// KeepAlive packet is not handled, so client might
+		// exit because of "time out".
+	}
+}
+
+type PlayerInfo struct {
+	Name    string
+	UUID    uuid.UUID
+	OPLevel int
+}
+
+// acceptLogin check player's account
+func acceptLogin(conn net.Conn) (info PlayerInfo, err error) {
+	//login start
+	var p pk.Packet
+	err = conn.ReadPacket(&p)
+	if err != nil {
+		return
+	}
+
+	err = p.Scan((*pk.String)(&info.Name)) //decode username as pk.String
+	if err != nil {
+		return
+	}
+
+	//auth
+	const OnlineMode = false
+	if OnlineMode {
+		log.Panic("Not Implement")
+	} else {
+		// offline-mode UUID
+		info.UUID = offline.NameToUUID(info.Name)
+	}
+
+	return
+}
+
+// handshake receive and parse Handshake packet
+func handshake(conn net.Conn) (protocol, intention int32, err error) {
+	var (
+		p                   pk.Packet
+		Protocol, Intention pk.VarInt
+		ServerAddress       pk.String        // ignored
+		ServerPort          pk.UnsignedShort // ignored
+	)
+	// receive handshake packet
+	if err = conn.ReadPacket(&p); err != nil {
+		return
+	}
+	err = p.Scan(&Protocol, &ServerAddress, &ServerPort, &Intention)
+	return int32(Protocol), int32(Intention), err
+}
+
+// loginSuccess send LoginSuccess packet to client
+func loginSuccess(conn net.Conn, name string, uuid uuid.UUID) error {
+	return conn.WritePacket(pk.Marshal(0x02,
+		pk.String(uuid.String()), //uuid as string with hyphens
+		pk.String(name),
+	))
+}
+
+func joinGame(conn net.Conn) error {
+	return conn.WritePacket(pk.Marshal(JoinGame,
+		pk.Int(0),                  // EntityID
+		pk.UnsignedByte(1),         // Gamemode
+		pk.Int(0),                  // Dimension
+		pk.Long(0),                 // HashedSeed
+		pk.UnsignedByte(MaxPlayer), // MaxPlayer
+		pk.String("default"),       // LevelType
+		pk.VarInt(15),              // View Distance
+		pk.Boolean(false),          // Reduced Debug Info
+		pk.Boolean(true),           // Enable respawn screen
+	))
+}