path: root/ethwire/messaging.go

package ethwire

import (
    "bytes"
    "errors"
    "fmt"
    "github.com/ethereum/eth-go/ethutil"
    "net"
    "time"
)

// Message:
// [4 bytes token] RLP([TYPE, DATA])
// Refer to http://wiki.ethereum.org/index.php/Wire_Protocol

// The magic token which should be the first 4 bytes of every message.
var MagicToken = []byte{34, 64, 8, 145}

type MsgType byte

const (
    // Values are given explicitly instead of by iota because these values are
    // defined by the wire protocol spec; it is easier for humans to ensure
    // correctness when values are explicit.
    MsgHandshakeTy  = 0x00
    MsgDiscTy       = 0x01
    MsgPingTy       = 0x02
    MsgPongTy       = 0x03
    MsgGetPeersTy   = 0x10
    MsgPeersTy      = 0x11
    MsgTxTy         = 0x12
    MsgBlockTy      = 0x13
    MsgGetChainTy   = 0x14
    MsgNotInChainTy = 0x15

    MsgTalkTy = 0xff
)

var msgTypeToString = map[MsgType]string{
    MsgHandshakeTy:  "Handshake",
    MsgDiscTy:       "Disconnect",
    MsgPingTy:       "Ping",
    MsgPongTy:       "Pong",
    MsgGetPeersTy:   "Get peers",
    MsgPeersTy:      "Peers",
    MsgTxTy:         "Transactions",
    MsgBlockTy:      "Blocks",
    MsgGetChainTy:   "Get chain",
    MsgNotInChainTy: "Not in chain",
}

func (mt MsgType) String() string {
    return msgTypeToString[mt]
}

type Msg struct {
    Type MsgType // Specifies how the encoded data should be interpreted
    //Data []byte
    Data *ethutil.Value
}

func NewMessage(msgType MsgType, data interface{}) *Msg {
    return &Msg{
        Type: msgType,
        Data: ethutil.NewValue(data),
    }
}

func ReadMessage(data []byte) (msg *Msg, remaining []byte, done bool, err error) {
    if len(data) == 0 {
        return nil, nil, true, nil
    }

    if len(data) <= 8 {
        return nil, remaining, false, errors.New("Invalid message")
    }

    // Check if the received 4 first bytes are the magic token
    if bytes.Compare(MagicToken, data[:4]) != 0 {
        return nil, nil, false, fmt.Errorf("MagicToken mismatch. Received %v", data[:4])
    }

    messageLength := ethutil.BytesToNumber(data[4:8])
    remaining = data[8+messageLength:]
    if int(messageLength) > len(data[8:]) {
        return nil, nil, false, fmt.Errorf("message length %d, expected %d", len(data[8:]), messageLength)
    }

    message := data[8 : 8+messageLength]
    decoder := ethutil.NewValueFromBytes(message)
    // Type of message
    t := decoder.Get(0).Uint()
    // Actual data
    d := decoder.SliceFrom(1)

    msg = &Msg{
        Type: MsgType(t),
        Data: d,
    }

    return
}

func bufferedRead(conn net.Conn) ([]byte, error) {
    return nil, nil
}

// The basic message reader waits for data on the given connection, decoding
// and doing a few sanity checks such as if there's a data type and
// unmarhals the given data
func ReadMessages(conn net.Conn) (msgs []*Msg, err error) {
    // The recovering function in case anything goes horribly wrong
    defer func() {
        if r := recover(); r != nil {
            err = fmt.Errorf("ethwire.ReadMessage error: %v", r)
        }
    }()

    // Buff for writing network message to
    //buff := make([]byte, 1440)
    var buff []byte
    var totalBytes int
    for {
        // Give buffering some time
        conn.SetReadDeadline(time.Now().Add(20 * time.Millisecond))
        // Create a new temporarily buffer
        b := make([]byte, 1440)
        // Wait for a message from this peer
        n, _ := conn.Read(b)
        if err != nil && n == 0 {
            if err.Error() != "EOF" {
                fmt.Println("err now", err)
                return nil, err
            } else {
                fmt.Println("IOF NOW")
                break
            }

            // Messages can't be empty
        } else if n == 0 {
            break
        }

        buff = append(buff, b[:n]...)
        totalBytes += n
    }

    // Reslice buffer
    buff = buff[:totalBytes]
    msg, remaining, done, err := ReadMessage(buff)
    for ; done != true; msg, remaining, done, err = ReadMessage(remaining) {
        //log.Println("rx", msg)

        if msg != nil {
            msgs = append(msgs, msg)
        }
    }

    return
}

// The basic message writer takes care of writing data over the given
// connection and does some basic error checking
func WriteMessage(conn net.Conn, msg *Msg) error {
    var pack []byte

    // Encode the type and the (RLP encoded) data for sending over the wire
    encoded := ethutil.NewValue(append([]interface{}{byte(msg.Type)}, msg.Data.Slice()...)).Encode()
    payloadLength := ethutil.NumberToBytes(uint32(len(encoded)), 32)

    // Write magic token and payload length (first 8 bytes)
    pack = append(MagicToken, payloadLength...)
    pack = append(pack, encoded...)
    //fmt.Printf("payload %v (%v) %q\n", msg.Type, conn.RemoteAddr(), encoded)

    // Write to the connection
    _, err := conn.Write(pack)
    if err != nil {
        return err
    }

    return nil
}