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// Package wire provides low level access to the Ethereum network and allows
// you to broadcast data over the network.
package wire
import (
"bytes"
"fmt"
"net"
"time"
"github.com/ethereum/go-ethereum/ethutil"
)
// Connection interface describing the methods required to implement the wire protocol.
type Conn interface {
Write(typ MsgType, v ...interface{}) error
Read() *Msg
}
// The magic token which should be the first 4 bytes of every message and can be used as separator between messages.
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 = 0x04
MsgPeersTy = 0x05
MsgStatusTy = 0x10
MsgTxTy = 0x12
MsgGetBlockHashesTy = 0x13
MsgBlockHashesTy = 0x14
MsgGetBlocksTy = 0x15
MsgBlockTy = 0x16
MsgNewBlockTy = 0x17
)
var msgTypeToString = map[MsgType]string{
MsgHandshakeTy: "Handshake",
MsgDiscTy: "Disconnect",
MsgPingTy: "Ping",
MsgPongTy: "Pong",
MsgGetPeersTy: "Get peers",
MsgStatusTy: "Status",
MsgPeersTy: "Peers",
MsgTxTy: "Transactions",
MsgBlockTy: "Blocks",
//MsgGetTxsTy: "Get Txs",
MsgGetBlockHashesTy: "Get block hashes",
MsgBlockHashesTy: "Block hashes",
MsgGetBlocksTy: "Get blocks",
}
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),
}
}
type Messages []*Msg
// 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("wire.ReadMessage error: %v", r)
}
}()
var (
buff []byte
messages [][]byte
msgLength int
)
for {
// Give buffering some time
conn.SetReadDeadline(time.Now().Add(5 * time.Millisecond))
// Create a new temporarily buffer
b := make([]byte, 1440)
n, _ := conn.Read(b)
if err != nil && n == 0 {
if err.Error() != "EOF" {
fmt.Println("err now", err)
return nil, err
} else {
break
}
}
if n == 0 && len(buff) == 0 {
// If there's nothing on the wire wait for a bit
time.Sleep(200 * time.Millisecond)
continue
}
buff = append(buff, b[:n]...)
if msgLength == 0 {
// Check if the received 4 first bytes are the magic token
if bytes.Compare(MagicToken, buff[:4]) != 0 {
return nil, fmt.Errorf("MagicToken mismatch. Received %v", buff[:4])
}
// Read the length of the message
msgLength = int(ethutil.BytesToNumber(buff[4:8]))
// Remove the token and length
buff = buff[8:]
}
if len(buff) >= msgLength {
messages = append(messages, buff[:msgLength])
buff = buff[msgLength:]
msgLength = 0
if len(buff) == 0 {
break
}
}
}
for _, m := range messages {
decoder := ethutil.NewValueFromBytes(m)
// Type of message
t := decoder.Get(0).Uint()
// Actual data
d := decoder.SliceFrom(1)
msgs = append(msgs, &Msg{Type: MsgType(t), Data: d})
}
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
}
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