package network import ( "errors" "fmt" "github.com/nspcc-dev/neo-go/pkg/core/block" "github.com/nspcc-dev/neo-go/pkg/core/transaction" "github.com/nspcc-dev/neo-go/pkg/io" "github.com/nspcc-dev/neo-go/pkg/network/payload" ) //go:generate stringer -type=CommandType -output=message_string.go // CompressionMinSize is the lower bound to apply compression. const CompressionMinSize = 1024 // Message is the complete message send between nodes. type Message struct { // Flags that represents whether a message is compressed. // 0 for None, 1 for Compressed. Flags MessageFlag // Command is byte command code. Command CommandType // Payload send with the message. Payload payload.Payload // Compressed message payload. compressedPayload []byte // StateRootInHeader specifies if state root is included in block header. // This is needed for correct decoding. StateRootInHeader bool } // MessageFlag represents compression level of message payload type MessageFlag byte // Possible message flags const ( Compressed MessageFlag = 1 << iota None MessageFlag = 0 ) // CommandType represents the type of a message command. type CommandType byte // Valid protocol commands used to send between nodes. const ( // handshaking CMDVersion CommandType = 0x00 CMDVerack CommandType = 0x01 // connectivity CMDGetAddr CommandType = 0x10 CMDAddr CommandType = 0x11 CMDPing CommandType = 0x18 CMDPong CommandType = 0x19 // synchronization CMDGetHeaders CommandType = 0x20 CMDHeaders CommandType = 0x21 CMDGetBlocks CommandType = 0x24 CMDMempool CommandType = 0x25 CMDInv CommandType = 0x27 CMDGetData CommandType = 0x28 CMDGetBlockByIndex CommandType = 0x29 CMDNotFound CommandType = 0x2a CMDTX = CommandType(payload.TXType) CMDBlock = CommandType(payload.BlockType) CMDExtensible = CommandType(payload.ExtensibleType) CMDP2PNotaryRequest = CommandType(payload.P2PNotaryRequestType) CMDReject CommandType = 0x2f // SPV protocol CMDFilterLoad CommandType = 0x30 CMDFilterAdd CommandType = 0x31 CMDFilterClear CommandType = 0x32 CMDMerkleBlock CommandType = 0x38 // others CMDAlert CommandType = 0x40 ) // NewMessage returns a new message with the given payload. func NewMessage(cmd CommandType, p payload.Payload) *Message { return &Message{ Command: cmd, Payload: p, Flags: None, } } // Decode decodes a Message from the given reader. func (m *Message) Decode(br *io.BinReader) error { m.Flags = MessageFlag(br.ReadB()) m.Command = CommandType(br.ReadB()) l := br.ReadVarUint() // check the length first in order not to allocate memory // for an empty compressed payload if l == 0 { switch m.Command { case CMDFilterClear, CMDGetAddr, CMDMempool, CMDVerack: m.Payload = payload.NewNullPayload() default: return fmt.Errorf("unexpected empty payload: %s", m.Command) } return nil } if l > payload.MaxSize { return errors.New("invalid payload size") } m.compressedPayload = make([]byte, l) br.ReadBytes(m.compressedPayload) if br.Err != nil { return br.Err } return m.decodePayload() } func (m *Message) decodePayload() error { buf := m.compressedPayload // try decompression if m.Flags&Compressed != 0 { d, err := decompress(m.compressedPayload) if err != nil { return err } buf = d } r := io.NewBinReaderFromBuf(buf) var p payload.Payload switch m.Command { case CMDVersion: p = &payload.Version{} case CMDInv, CMDGetData: p = &payload.Inventory{} case CMDAddr: p = &payload.AddressList{} case CMDBlock: p = block.New(m.StateRootInHeader) case CMDExtensible: p = payload.NewExtensible() case CMDP2PNotaryRequest: p = &payload.P2PNotaryRequest{} case CMDGetBlocks: p = &payload.GetBlocks{} case CMDGetHeaders: fallthrough case CMDGetBlockByIndex: p = &payload.GetBlockByIndex{} case CMDHeaders: p = &payload.Headers{StateRootInHeader: m.StateRootInHeader} case CMDTX: p = &transaction.Transaction{} case CMDMerkleBlock: p = &payload.MerkleBlock{} case CMDPing, CMDPong: p = &payload.Ping{} case CMDNotFound: p = &payload.Inventory{} default: return fmt.Errorf("can't decode command %s", m.Command.String()) } p.DecodeBinary(r) if r.Err == nil || r.Err == payload.ErrTooManyHeaders { m.Payload = p } return r.Err } // Encode encodes a Message to any given BinWriter. func (m *Message) Encode(br *io.BinWriter) error { if err := m.tryCompressPayload(); err != nil { return err } br.WriteB(byte(m.Flags)) br.WriteB(byte(m.Command)) if m.compressedPayload != nil { br.WriteVarBytes(m.compressedPayload) } else { br.WriteB(0) } return br.Err } // Bytes serializes a Message into the new allocated buffer and returns it. func (m *Message) Bytes() ([]byte, error) { w := io.NewBufBinWriter() if err := m.Encode(w.BinWriter); err != nil { return nil, err } return w.Bytes(), nil } // tryCompressPayload sets message's compressed payload to serialized // payload and compresses it in case if its size exceeds CompressionMinSize func (m *Message) tryCompressPayload() error { if m.Payload == nil { return nil } buf := io.NewBufBinWriter() m.Payload.EncodeBinary(buf.BinWriter) if buf.Err != nil { return buf.Err } compressedPayload := buf.Bytes() if m.Flags&Compressed == 0 { switch m.Payload.(type) { case *payload.Headers, *payload.MerkleBlock, payload.NullPayload, *payload.Inventory: break default: size := len(compressedPayload) // try compression if size > CompressionMinSize { c, err := compress(compressedPayload) if err == nil { compressedPayload = c m.Flags |= Compressed } else { return err } } } } m.compressedPayload = compressedPayload return nil }