lnwire: update and document message.go
This commit is contained in:
Olaoluwa Osuntokun
parent
0563205e6d
commit
a30831aef8
@ -9,55 +9,65 @@ import (
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"github.com/roasbeef/btcd/wire"
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)
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// 4-byte network + 4-byte message id + payload-length 4-byte
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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 = 1024 * 1024 * 32 // 32MB
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// Commands used in lightning message headers which detail the type of message.
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const (
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// Funding channel open
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// Commands for opening a channel funded by both parties (dual funder).
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CmdFundingRequest = uint32(200)
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CmdFundingResponse = uint32(210)
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CmdFundingSignAccept = uint32(220)
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CmdFundingSignComplete = uint32(230)
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// Close channel
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// Commands for opening a channel funded by one party (single funder).
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CmdSingleFundingRequest = uint32(100)
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CmdSingleFundingResponse = uint32(110)
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CmdSingleFundingComplete = uint32(120)
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CmdSingleFundingSignComplete = uint32(130)
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CmdSingleFundingOpenProof = uint32(140)
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// Commands for the workflow of cooperatively closing an active channel.
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CmdCloseRequest = uint32(300)
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CmdCloseComplete = uint32(310)
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// TODO Renumber to 1100
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// HTLC payment
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CmdHTLCAddRequest = uint32(1000)
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CmdHTLCAddAccept = uint32(1010)
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CmdHTLCAddReject = uint32(1020)
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// TODO Renumber to 1200
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// HTLC settlement
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CmdHTLCSettleRequest = uint32(1100)
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CmdHTLCSettleAccept = uint32(1110)
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// HTLC timeout
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// Commands for negotiating HTLCs.
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CmdHTLCAddRequest = uint32(1000)
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CmdHTLCAddAccept = uint32(1010)
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CmdHTLCAddReject = uint32(1020)
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CmdHTLCSettleRequest = uint32(1100)
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CmdHTLCTimeoutRequest = uint32(1300)
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CmdHTLCTimeoutAccept = uint32(1310)
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// Commitments
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// Commands for modifying commitment transactions.
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CmdCommitSignature = uint32(2000)
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CmdCommitRevocation = uint32(2010)
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// Error
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// Commands for reporting protocol errors.
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CmdErrorGeneric = uint32(4000)
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)
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// Every message has these functions:
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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 // (io, protocol version)
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Encode(io.Writer, uint32) error // (io, protocol version)
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Command() uint32 // returns ID of the message
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MaxPayloadLength(uint32) uint32 // (version) maxpayloadsize
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Validate() error // Validates the data struct
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Decode(io.Reader, uint32) error
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Encode(io.Writer, uint32) error
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Command() uint32
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MaxPayloadLength(uint32) uint32
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Validate() error
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String() string
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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 command ID.
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func makeEmptyMessage(command uint32) (Message, error) {
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var msg Message
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@ -70,24 +80,28 @@ func makeEmptyMessage(command uint32) (Message, error) {
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msg = &FundingSignAccept{}
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case CmdFundingSignComplete:
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msg = &FundingSignComplete{}
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case CmdSingleFundingRequest:
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msg = &SingleFundingRequest{}
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case CmdSingleFundingResponse:
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msg = &SingleFundingResponse{}
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case CmdSingleFundingComplete:
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msg = &SingleFundingComplete{}
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case CmdSingleFundingSignComplete:
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msg = &SingleFundingSignComplete{}
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case CmdSingleFundingOpenProof:
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msg = &SingleFundingOpenProof{}
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case CmdCloseRequest:
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msg = &CloseRequest{}
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case CmdCloseComplete:
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msg = &CloseComplete{}
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case CmdHTLCAddRequest:
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msg = &HTLCAddRequest{}
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case CmdHTLCAddAccept:
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msg = &HTLCAddAccept{}
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case CmdHTLCAddReject:
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msg = &HTLCAddReject{}
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case CmdHTLCSettleRequest:
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msg = &HTLCSettleRequest{}
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case CmdHTLCSettleAccept:
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msg = &HTLCSettleAccept{}
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case CmdHTLCTimeoutRequest:
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msg = &HTLCTimeoutRequest{}
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case CmdHTLCTimeoutAccept:
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msg = &HTLCTimeoutAccept{}
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case CmdCommitSignature:
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msg = &CommitSignature{}
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case CmdCommitRevocation:
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@ -101,16 +115,22 @@ func makeEmptyMessage(command uint32) (Message, error) {
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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 // which Blockchain Technology(TM) to use
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command uint32
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length uint32
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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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@ -118,8 +138,8 @@ func readMessageHeader(r io.Reader) (int, *messageHeader, error) {
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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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@ -131,10 +151,10 @@ func readMessageHeader(r io.Reader) (int, *messageHeader, error) {
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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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// 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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@ -151,7 +171,11 @@ func discardInput(r io.Reader, n uint32) {
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}
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}
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func WriteMessage(w io.Writer, msg Message, pver uint32, btcnet wire.BitcoinNet) (int, error) {
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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,
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btcnet wire.BitcoinNet) (int, error) {
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totalBytes := 0
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cmd := msg.Command()
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@ -167,35 +191,38 @@ func WriteMessage(w io.Writer, msg Message, pver uint32, btcnet wire.BitcoinNet)
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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 - encoded %d bytes, but maximum message payload is %d bytes", 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 - encoded %d bytes, but maximum message payload of type %x is %d bytes", lenp, cmd, 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{}
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hdr.magic = btcnet
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hdr.command = cmd
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hdr.length = uint32(lenp)
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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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// 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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writeElements(hw, hdr.magic, hdr.command, hdr.length)
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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 header
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// Write the head 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
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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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if err != nil {
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@ -205,6 +232,11 @@ func WriteMessage(w io.Writer, msg Message, pver uint32, btcnet wire.BitcoinNet)
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return totalBytes, nil
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}
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// ReadMessageN 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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@ -215,31 +247,38 @@ func ReadMessage(r io.Reader, pver uint32, btcnet wire.BitcoinNet) (int, Message
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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 too large - header indicates %d bytes, but max message payload is %d bytes.", 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 bitcoin network
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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 network [%v]", hdr.magic)
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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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// 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, fmt.Errorf("ReadMessage %s", err.Error())
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return totalBytes, nil, nil, fmt.Errorf("ReadMessage %s",
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err.Error())
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}
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// Check for maximum length based on the message type
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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 length. indicates %v bytes, but max of message type %v is %v.", hdr.length, command, mpl)
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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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// 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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@ -247,19 +286,16 @@ func ReadMessage(r io.Reader, pver uint32, btcnet wire.BitcoinNet) (int, Message
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return totalBytes, nil, nil, err
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}
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// Unmarshal message
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// Unmarshal message.
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pr := bytes.NewBuffer(payload)
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err = msg.Decode(pr, pver)
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if err != nil {
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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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err = msg.Validate()
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if err != nil {
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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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// We're good!
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return totalBytes, msg, payload, nil
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}
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