package wire import ( "bufio" "bytes" "errors" "io" "github.com/CityOfZion/neo-go/pkg/wire/payload/transaction" checksum "github.com/CityOfZion/neo-go/pkg/wire/util/Checksum" "github.com/CityOfZion/neo-go/pkg/wire/command" "github.com/CityOfZion/neo-go/pkg/wire/payload" "github.com/CityOfZion/neo-go/pkg/wire/protocol" "github.com/CityOfZion/neo-go/pkg/wire/util" ) // Messager is implemented by any object that can // Encode and Decode Payloads type Messager interface { // EncodePayload takes a message payload and encodes it EncodePayload(w io.Writer) error // DecodePayload takes an io.Reader and decodes it into // a message payload DecodePayload(r io.Reader) error // Command returns the assosciated command type Command() command.Type } const ( // Magic + cmd + length + checksum minMsgSize = 4 + 12 + 4 + 4 ) var ( errChecksumMismatch = errors.New("checksum mismatch") ) // WriteMessage will write a message to a given io.Writer func WriteMessage(w io.Writer, magic protocol.Magic, message Messager) error { bw := &util.BinWriter{W: w} bw.Write(magic) bw.Write(cmdToByteArray(message.Command())) buf := new(bytes.Buffer) if err := message.EncodePayload(buf); err != nil { return err } payloadLen := uint32(buf.Len()) checksum := checksum.FromBytes(buf.Bytes()) bw.Write(payloadLen) bw.Write(checksum) bw.WriteBigEnd(buf.Bytes()) return bw.Err } // ReadMessage will read a message from a given io.Reader func ReadMessage(r io.Reader, magic protocol.Magic) (Messager, error) { byt := make([]byte, minMsgSize) if _, err := io.ReadFull(r, byt); err != nil { return nil, err } reader := bytes.NewReader(byt) var header Base _, err := header.DecodeBase(reader) if err != nil { return nil, errors.New("Error decoding into the header base") } buf := new(bytes.Buffer) _, err = io.CopyN(buf, r, int64(header.PayloadLength)) if err != nil { return nil, err } // Compare the checksum of the payload. if !checksum.Compare(header.Checksum, buf.Bytes()) { return nil, errChecksumMismatch } switch header.CMD { case command.Version: v := &payload.VersionMessage{} err := v.DecodePayload(buf) return v, err case command.Verack: v, err := payload.NewVerackMessage() err = v.DecodePayload(buf) return v, err case command.Inv: v, err := payload.NewInvMessage(0) err = v.DecodePayload(buf) return v, err case command.GetAddr: v, err := payload.NewGetAddrMessage() err = v.DecodePayload(buf) return v, err case command.Addr: v, err := payload.NewAddrMessage() err = v.DecodePayload(buf) return v, err case command.Block: v, err := payload.NewBlockMessage() err = v.DecodePayload(buf) return v, err case command.GetBlocks: v, err := payload.NewGetBlocksMessage([]util.Uint256{}, util.Uint256{}) err = v.DecodePayload(buf) return v, err case command.GetData: v, err := payload.NewGetDataMessage(payload.InvTypeTx) err = v.DecodePayload(buf) return v, err case command.GetHeaders: v, err := payload.NewGetHeadersMessage([]util.Uint256{}, util.Uint256{}) err = v.DecodePayload(buf) return v, err case command.Headers: v, err := payload.NewHeadersMessage() err = v.DecodePayload(buf) return v, err case command.TX: reader := bufio.NewReader(buf) tx, err := transaction.FromReader(reader) if err != nil { return nil, err } return payload.NewTXMessage(tx) } return nil, errors.New("Unknown Message found") } func cmdToByteArray(cmd command.Type) [command.Size]byte { cmdLen := len(cmd) if cmdLen > command.Size { panic("exceeded command max length of size 12") } // The command can have max 12 bytes, rest is filled with 0. b := [command.Size]byte{} for i := 0; i < cmdLen; i++ { b[i] = cmd[i] } return b }