Initial commit

mcproto/types.go

@@ -0,0 +1,168 @@
+package mcproto
+
+import (
+	"errors"
+	"bytes"
+	"strings"
+	"io"
+)
+
+type Frame struct {
+	Length int
+	Payload []byte
+}
+
+type Packet struct {
+	Length int
+	PacketID int
+	Data []byte
+}
+
+const PacketIdHandshake = 0x00
+type Handshake struct {
+	ProtocolVersion int
+	ServerAddress string
+	ServerPort uint16
+	NextState int
+}
+
+type ByteReader interface {
+	ReadByte() (byte, error)
+}
+
+func ReadVarInt(reader io.Reader) (int, error) {
+	b := make([]byte, 1)
+	var numRead uint = 0
+	result := 0
+	for numRead <= 5 {
+		n, err := reader.Read(b)
+		if err != nil {
+			return 0, err
+		}
+		if n == 0 {
+			continue
+		}
+		value := b[0] & 0x7F
+		result |= int(value) << (7*numRead)
+
+		numRead++
+
+		if b[0] & 0x80 == 0 {
+			return result, nil
+		}
+	}
+
+	return 0, errors.New("VarInt is too big")
+}
+
+func ReadString(reader io.Reader) (string, error) {
+	length, err := ReadVarInt(reader)
+	if err != nil {
+		return "", err
+	}
+
+	b := make([]byte, 1)
+	var strBuilder strings.Builder
+	for i := 0; i < length; i++ {
+		n, err := reader.Read(b)
+		if err != nil {
+			return "", err
+		}
+		if n == 0 {
+			continue
+		}
+		strBuilder.WriteByte(b[0])
+	}
+
+	return strBuilder.String(), nil
+}
+
+func ReadUnsignedShort(reader io.Reader) (uint16, error) {
+	upper := make([]byte, 1)
+	_, err := reader.Read(upper)
+	if err != nil {
+		return 0, err
+	}
+	lower := make([]byte, 1)
+	_, err = reader.Read(lower)
+	if err != nil {
+		return 0, err
+	}
+
+	return (uint16(upper[0])<<8) | uint16(lower[0]), nil
+}
+
+func ReadFrame(reader io.Reader) (*Frame, error) {
+	var err error
+	frame := &Frame{}
+
+	frame.Length, err = ReadVarInt(reader)
+	if err != nil {
+		return nil, err
+	}
+
+	frame.Payload = make([]byte, frame.Length)
+	total := 0
+	for total < frame.Length {
+		readIntoThis := frame.Payload[total:]
+		n, err := reader.Read(readIntoThis)
+		if err != nil {
+			if err != io.EOF {
+				return nil, err
+			}
+		}
+		total += n
+	}
+
+	return frame, nil
+}
+
+func ReadPacket(reader io.Reader) (*Packet, error) {
+
+	frame, err := ReadFrame(reader)
+	if err != nil {
+		return nil, err
+	}
+
+	packet := &Packet{Length:frame.Length}
+
+	remainder := bytes.NewBuffer(frame.Payload)
+
+	packet.PacketID, err = ReadVarInt(remainder)
+	if err != nil {
+		return nil, err
+	}
+
+	packet.Data = remainder.Bytes()
+
+	return packet, nil
+}
+
+func ReadHandshake(data []byte) (*Handshake, error) {
+
+	handshake := &Handshake{}
+	buffer := bytes.NewBuffer(data)
+	var err error
+
+	handshake.ProtocolVersion, err = ReadVarInt(buffer)
+	if err != nil {
+		return nil, err
+	}
+
+	handshake.ServerAddress, err = ReadString(buffer)
+	if err != nil {
+		return nil, err
+	}
+
+	handshake.ServerPort, err = ReadUnsignedShort(buffer)
+	if err != nil {
+		return nil, err
+	}
+
+	nextState, err := ReadVarInt(buffer)
+	if err != nil {
+		return nil, err
+	}
+	handshake.NextState = nextState
+	return handshake, nil
+}