mirror of https://github.com/BTCPrivate/lnd.git
309 lines
9.3 KiB
Go
309 lines
9.3 KiB
Go
package lnwire
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// code derived from https://github .com/btcsuite/btcd/blob/master/wire/message.go
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"io"
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)
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// MessageHeaderSize is the number of bytes in a lightning message header.
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// The bytes are allocated as follows: network magic 4 bytes + command 4
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// bytes + payload length 4 bytes. Note that a checksum is omitted as lightning
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// messages are assumed to be transmitted over an AEAD secured connection which
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// provides integrity over the entire message.
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const MessageHeaderSize = 12
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// MaxMessagePayload is the maximum bytes a message can be regardless of other
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// individual limits imposed by messages themselves.
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const MaxMessagePayload = 65535 // 65KB
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// MessageType is the unique 2 byte big-endian integer that indicates the type
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// of message on the wire. All messages have a very simple header which
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// consists simply of 2-byte message type. We omit a length field, and checksum
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// as the Lighting Protocol is intended to be encapsulated within a
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// confidential+authenticated cryptographic messaging protocol.
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type MessageType uint16
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const (
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MsgInit MessageType = 16
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MsgError = 17
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MsgPing = 18
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MsgPong = 19
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MsgSingleFundingRequest = 32
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MsgSingleFundingResponse = 33
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MsgSingleFundingComplete = 34
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MsgSingleFundingSignComplete = 35
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MsgFundingLocked = 36
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MsgCloseRequest = 39
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MsgCloseComplete = 40
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MsgUpdateAddHTLC = 128
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MsgUpdateFufillHTLC = 130
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MsgUpdateFailHTLC = 131
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MsgCommitSig = 132
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MsgRevokeAndAck = 133
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MsgChannelAnnouncement = 256
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MsgNodeAnnouncement = 257
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MsgChannelUpdate = 258
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MsgAnnounceSignatures = 259
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)
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// UnknownMessage is an implementation of the error interface that allows the
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// creation of an error in response to an unknown message.
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type UnknownMessage struct {
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messageType MessageType
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}
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// Error returns a human readable string describing the error.
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//
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// This is part of the error interface.
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func (u *UnknownMessage) Error() string {
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return fmt.Sprintf("unable to parse message of unknown type: %v",
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u.messageType)
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}
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// Message is an interface that defines a lightning wire protocol message. The
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// interface is general in order to allow implementing types full control over
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// the representation of its data.
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type Message interface {
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Decode(io.Reader, uint32) error
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Encode(io.Writer, uint32) error
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MsgType() MessageType
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MaxPayloadLength(uint32) uint32
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}
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// makeEmptyMessage creates a new empty message of the proper concrete type
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// based on the passed message type.
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func makeEmptyMessage(msgType MessageType) (Message, error) {
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var msg Message
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switch msgType {
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case MsgInit:
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msg = &Init{}
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case MsgSingleFundingRequest:
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msg = &SingleFundingRequest{}
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case MsgSingleFundingResponse:
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msg = &SingleFundingResponse{}
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case MsgSingleFundingComplete:
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msg = &SingleFundingComplete{}
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case MsgSingleFundingSignComplete:
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msg = &SingleFundingSignComplete{}
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case MsgFundingLocked:
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msg = &FundingLocked{}
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case MsgCloseRequest:
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msg = &CloseRequest{}
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case MsgCloseComplete:
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msg = &CloseComplete{}
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case MsgUpdateAddHTLC:
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msg = &UpdateAddHTLC{}
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case MsgUpdateFailHTLC:
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msg = &UpdateFailHTLC{}
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case MsgUpdateFufillHTLC:
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msg = &UpdateFufillHTLC{}
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case MsgCommitSig:
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msg = &CommitSig{}
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case MsgRevokeAndAck:
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msg = &RevokeAndAck{}
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case MsgError:
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msg = &Error{}
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case MsgChannelAnnouncement:
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msg = &ChannelAnnouncement{}
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case MsgChannelUpdate:
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msg = &ChannelUpdate{}
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case MsgNodeAnnouncement:
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msg = &NodeAnnouncement{}
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case MsgPing:
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msg = &Ping{}
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case MsgAnnounceSignatures:
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msg = &AnnounceSignatures{}
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case MsgPong:
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msg = &Pong{}
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default:
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return nil, fmt.Errorf("unknown message type [%d]", msgType)
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}
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return msg, nil
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}
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// messageHeader represents the header structure for all lightning protocol
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// messages.
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type messageHeader struct {
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// magic represents Which Blockchain Technology(TM) to use.
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// NOTE(j): We don't need to worry about the magic overlapping with
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// bitcoin since this is inside encrypted comms anyway, but maybe we
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// should use the XOR (^wire.TestNet3) just in case???
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magic wire.BitcoinNet // 4 bytes
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command uint32 // 4 bytes
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length uint32 // 4 bytes
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}
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// readMessageHeader reads a lightning protocol message header from r.
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func readMessageHeader(r io.Reader) (int, *messageHeader, error) {
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// As the message header is a fixed size structure, read bytes for the
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// entire header at once.
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var headerBytes [MessageHeaderSize]byte
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n, err := io.ReadFull(r, headerBytes[:])
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if err != nil {
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return n, nil, err
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}
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hr := bytes.NewReader(headerBytes[:])
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// Create and populate the message header from the raw header bytes.
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hdr := messageHeader{}
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err = readElements(hr,
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&hdr.magic,
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&hdr.command,
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&hdr.length)
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if err != nil {
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return n, nil, err
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}
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return n, &hdr, nil
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}
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// discardInput reads n bytes from reader r in chunks and discards the read
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// bytes. This is used to skip payloads when various errors occur and helps
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// prevent rogue nodes from causing massive memory allocation through forging
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// header length.
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func discardInput(r io.Reader, n uint32) {
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maxSize := uint32(10 * 1024) // 10k at a time
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numReads := n / maxSize
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bytesRemaining := n % maxSize
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if n > 0 {
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buf := make([]byte, maxSize)
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for i := uint32(0); i < numReads; i++ {
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io.ReadFull(r, buf)
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}
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}
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if bytesRemaining > 0 {
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buf := make([]byte, bytesRemaining)
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io.ReadFull(r, buf)
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}
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}
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// WriteMessage writes a lightning Message to w including the necessary header
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// information and returns the number of bytes written.
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func WriteMessage(w io.Writer, msg Message, pver uint32, btcnet wire.BitcoinNet) (int, error) {
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totalBytes := 0
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cmd := msg.Command()
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// Encode the message payload
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var bw bytes.Buffer
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err := msg.Encode(&bw, pver)
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if err != nil {
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return totalBytes, err
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}
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payload := bw.Bytes()
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lenp := len(payload)
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// Enforce maximum overall message payload
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if lenp > MaxMessagePayload {
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return totalBytes, fmt.Errorf("message payload is too large - "+
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"encoded %d bytes, but maximum message payload is %d bytes",
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lenp, MaxMessagePayload)
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}
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// Enforce maximum message payload on the message type
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mpl := msg.MaxPayloadLength(pver)
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if uint32(lenp) > mpl {
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return totalBytes, fmt.Errorf("message payload is too large - "+
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"encoded %d bytes, but maximum message payload of "+
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"type %x is %d bytes", lenp, cmd, mpl)
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}
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// Create header for the message.
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hdr := messageHeader{magic: btcnet, command: cmd, length: uint32(lenp)}
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// Encode the header for the message. This is done to a buffer
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// rather than directly to the writer since writeElements doesn't
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// return the number of bytes written.
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hw := bytes.NewBuffer(make([]byte, 0, MessageHeaderSize))
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if err := writeElements(hw, hdr.magic, hdr.command, hdr.length); err != nil {
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return 0, nil
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}
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// Write the header first.
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n, err := w.Write(hw.Bytes())
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totalBytes += n
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if err != nil {
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return totalBytes, err
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}
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// Write payload the payload itself after the header.
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n, err = w.Write(payload)
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totalBytes += n
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return totalBytes, err
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}
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// ReadMessage reads, validates, and parses the next bitcoin Message from r for
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// the provided protocol version and bitcoin network. It returns the number of
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// bytes read in addition to the parsed Message and raw bytes which comprise the
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// message. This function is the same as ReadMessage except it also returns the
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// number of bytes read.
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func ReadMessage(r io.Reader, pver uint32, btcnet wire.BitcoinNet) (int, Message, []byte, error) {
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totalBytes := 0
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n, hdr, err := readMessageHeader(r)
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totalBytes += n
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if err != nil {
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return totalBytes, nil, nil, err
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}
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// Enforce maximum message payload
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if hdr.length > MaxMessagePayload {
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return totalBytes, nil, nil, fmt.Errorf("message payload is "+
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"too large - header indicates %d bytes, but max "+
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"message payload is %d bytes.", hdr.length,
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MaxMessagePayload)
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}
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// Check for messages in the wrong network.
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if hdr.magic != btcnet {
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discardInput(r, hdr.length)
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return totalBytes, nil, nil, fmt.Errorf("message from other "+
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"network [%v]", hdr.magic)
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}
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// Create struct of appropriate message type based on the command.
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command := hdr.command
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msg, err := makeEmptyMessage(command)
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if err != nil {
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discardInput(r, hdr.length)
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return totalBytes, nil, nil, &UnknownMessage{
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messageType: command,
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}
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}
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// Check for maximum length based on the message type.
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mpl := msg.MaxPayloadLength(pver)
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if hdr.length > mpl {
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discardInput(r, hdr.length)
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return totalBytes, nil, nil, fmt.Errorf("payload exceeds max "+
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"length. indicates %v bytes, but max of message type %v is %v.",
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hdr.length, command, mpl)
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}
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// Read payload.
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payload := make([]byte, hdr.length)
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n, err = io.ReadFull(r, payload)
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totalBytes += n
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if err != nil {
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return totalBytes, nil, nil, err
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}
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// Unmarshal message.
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pr := bytes.NewBuffer(payload)
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if err = msg.Decode(pr, pver); err != nil {
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return totalBytes, nil, nil, err
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}
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// Validate the data.
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if err = msg.Validate(); err != nil {
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return totalBytes, nil, nil, err
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}
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return totalBytes, msg, payload, nil
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}
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