160 lines
4.6 KiB
Go
160 lines
4.6 KiB
Go
// Copyright (c) 2014-2016 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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// maxFlagsPerMerkleBlock is the maximum number of flag bytes that could
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// possibly fit into a merkle block. Since each transaction is represented by
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// a single bit, this is the max number of transactions per block divided by
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// 8 bits per byte. Then an extra one to cover partials.
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const maxFlagsPerMerkleBlock = maxTxPerBlock / 8
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// MsgMerkleBlock implements the Message interface and represents a bitcoin
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// merkleblock message which is used to reset a Bloom filter.
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//
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// This message was not added until protocol version BIP0037Version.
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type MsgMerkleBlock struct {
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Header BlockHeader
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Transactions uint32
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Hashes []*chainhash.Hash
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Flags []byte
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}
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// AddTxHash adds a new transaction hash to the message.
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func (msg *MsgMerkleBlock) AddTxHash(hash *chainhash.Hash) error {
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if len(msg.Hashes)+1 > maxTxPerBlock {
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str := fmt.Sprintf("too many tx hashes for message [max %v]",
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maxTxPerBlock)
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return messageError("MsgMerkleBlock.AddTxHash", str)
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}
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msg.Hashes = append(msg.Hashes, 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 *MsgMerkleBlock) BtcDecode(r io.Reader, pver uint32) error {
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if pver < BIP0037Version {
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str := fmt.Sprintf("merkleblock message invalid for protocol "+
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"version %d", pver)
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return messageError("MsgMerkleBlock.BtcDecode", str)
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}
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err := readBlockHeader(r, pver, &msg.Header)
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if err != nil {
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return err
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}
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err = readElement(r, &msg.Transactions)
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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 > maxTxPerBlock {
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str := fmt.Sprintf("too many transaction hashes for message "+
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"[count %v, max %v]", count, maxTxPerBlock)
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return messageError("MsgMerkleBlock.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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hashes := make([]chainhash.Hash, count)
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msg.Hashes = make([]*chainhash.Hash, 0, count)
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for i := uint64(0); i < count; i++ {
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hash := &hashes[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.AddTxHash(hash)
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}
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msg.Flags, err = ReadVarBytes(r, pver, maxFlagsPerMerkleBlock,
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"merkle block flags size")
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return err
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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 *MsgMerkleBlock) BtcEncode(w io.Writer, pver uint32) error {
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if pver < BIP0037Version {
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str := fmt.Sprintf("merkleblock message invalid for protocol "+
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"version %d", pver)
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return messageError("MsgMerkleBlock.BtcEncode", str)
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}
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// Read num transaction hashes and limit to max.
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numHashes := len(msg.Hashes)
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if numHashes > maxTxPerBlock {
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str := fmt.Sprintf("too many transaction hashes for message "+
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"[count %v, max %v]", numHashes, maxTxPerBlock)
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return messageError("MsgMerkleBlock.BtcDecode", str)
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}
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numFlagBytes := len(msg.Flags)
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if numFlagBytes > maxFlagsPerMerkleBlock {
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str := fmt.Sprintf("too many flag bytes for message [count %v, "+
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"max %v]", numFlagBytes, maxFlagsPerMerkleBlock)
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return messageError("MsgMerkleBlock.BtcDecode", str)
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}
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err := writeBlockHeader(w, pver, &msg.Header)
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if err != nil {
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return err
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}
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err = writeElement(w, msg.Transactions)
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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(numHashes))
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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.Hashes {
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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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return WriteVarBytes(w, pver, msg.Flags)
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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 *MsgMerkleBlock) Command() string {
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return CmdMerkleBlock
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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 *MsgMerkleBlock) MaxPayloadLength(pver uint32) uint32 {
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return MaxBlockPayload
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}
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// NewMsgMerkleBlock returns a new bitcoin merkleblock message that conforms to
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// the Message interface. See MsgMerkleBlock for details.
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func NewMsgMerkleBlock(bh *BlockHeader) *MsgMerkleBlock {
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return &MsgMerkleBlock{
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Header: *bh,
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Transactions: 0,
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Hashes: make([]*chainhash.Hash, 0),
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Flags: make([]byte, 0),
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}
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}
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