135 lines
3.9 KiB
Go
135 lines
3.9 KiB
Go
// Copyright (c) 2017 The btcsuite developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package wire
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import (
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"fmt"
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"io"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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)
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// MsgGetCFHeaders is a message similar to MsgGetHeaders, but for committed
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// filter headers. It allows to set the Extended field to get headers in the
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// chain of basic (false) or extended (true) headers.
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type MsgGetCFHeaders struct {
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ProtocolVersion uint32
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BlockLocatorHashes []*chainhash.Hash
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HashStop chainhash.Hash
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Extended bool
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}
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// AddBlockLocatorHash adds a new block locator hash to the message.
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func (msg *MsgGetCFHeaders) AddBlockLocatorHash(hash *chainhash.Hash) error {
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if len(msg.BlockLocatorHashes)+1 > MaxBlockLocatorsPerMsg {
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str := fmt.Sprintf("too many block locator hashes for message [max %v]",
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MaxBlockLocatorsPerMsg)
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return messageError("MsgGetCFHeaders.AddBlockLocatorHash", str)
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}
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msg.BlockLocatorHashes = append(msg.BlockLocatorHashes, hash)
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return nil
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}
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// BtcDecode decodes r using the bitcoin protocol encoding into the receiver.
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// This is part of the Message interface implementation.
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func (msg *MsgGetCFHeaders) BtcDecode(r io.Reader, pver uint32) error {
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err := readElement(r, &msg.ProtocolVersion)
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if err != nil {
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return err
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}
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// Read num block locator hashes and limit to max.
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count, err := ReadVarInt(r, pver)
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if err != nil {
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return err
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}
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if count > MaxBlockLocatorsPerMsg {
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str := fmt.Sprintf("too many block locator hashes for message "+
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"[count %v, max %v]", count, MaxBlockLocatorsPerMsg)
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return messageError("MsgGetHeaders.BtcDecode", str)
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}
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// Create a contiguous slice of hashes to deserialize into in order to
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// reduce the number of allocations.
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locatorHashes := make([]chainhash.Hash, count)
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msg.BlockLocatorHashes = make([]*chainhash.Hash, 0, count)
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for i := uint64(0); i < count; i++ {
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hash := &locatorHashes[i]
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err := readElement(r, hash)
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if err != nil {
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return err
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}
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msg.AddBlockLocatorHash(hash)
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}
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err = readElement(r, &msg.HashStop)
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if err != nil {
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return err
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}
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return readElement(r, &msg.Extended)
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}
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// BtcEncode encodes the receiver to w using the bitcoin protocol encoding.
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// This is part of the Message interface implementation.
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func (msg *MsgGetCFHeaders) BtcEncode(w io.Writer, pver uint32) error {
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// Limit to max block locator hashes per message.
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count := len(msg.BlockLocatorHashes)
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if count > MaxBlockLocatorsPerMsg {
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str := fmt.Sprintf("too many block locator hashes for message "+
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"[count %v, max %v]", count, MaxBlockLocatorsPerMsg)
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return messageError("MsgGetHeaders.BtcEncode", str)
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}
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err := writeElement(w, msg.ProtocolVersion)
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if err != nil {
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return err
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}
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err = WriteVarInt(w, pver, uint64(count))
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if err != nil {
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return err
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}
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for _, hash := range msg.BlockLocatorHashes {
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err := writeElement(w, hash)
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if err != nil {
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return err
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}
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}
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err = writeElement(w, &msg.HashStop)
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if err != nil {
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return err
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}
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return writeElement(w, msg.Extended)
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}
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// Command returns the protocol command string for the message. This is part
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// of the Message interface implementation.
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func (msg *MsgGetCFHeaders) Command() string {
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return CmdGetCFHeaders
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}
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// MaxPayloadLength returns the maximum length the payload can be for the
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// receiver. This is part of the Message interface implementation.
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func (msg *MsgGetCFHeaders) MaxPayloadLength(pver uint32) uint32 {
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// Version 4 bytes + num block locator hashes (varInt) + max allowed
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// block locators + hash stop + Extended flag 1 byte.
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return 4 + MaxVarIntPayload + (MaxBlockLocatorsPerMsg *
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chainhash.HashSize) + chainhash.HashSize + 1
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}
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// NewMsgGetCFHeaders returns a new bitcoin getcfheader message that conforms to
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// the Message interface using the passed parameters and defaults for the
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// remaining fields.
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func NewMsgGetCFHeaders() *MsgGetCFHeaders {
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return &MsgGetCFHeaders{
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BlockLocatorHashes: make([]*chainhash.Hash, 0,
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MaxBlockLocatorsPerMsg),
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}
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}
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