forked from Roasbeef/btcd
/
blockheader.go
156 lines (128 loc) · 5.34 KB
/
blockheader.go
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// Copyright (c) 2013-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package wire
import (
"bytes"
"io"
"time"
"golang.org/x/crypto/scrypt"
"github.com/adiabat/btcd/chaincfg/chainhash"
)
// BlockVersion is the current latest supported block version.
const BlockVersion = 4
// MaxBlockHeaderPayload is the maximum number of bytes a block header can be.
// Version 4 bytes + Timestamp 4 bytes + Bits 4 bytes + Nonce 4 bytes +
// PrevBlock and MerkleRoot hashes.
//const MaxBlockHeaderPayload = 16 + (chainhash.HashSize * 2)
const MaxBlockHeaderPayload = 16 + (chainhash.HashSize * 2) + 500
// BlockHeader defines information about a block and is used in the bitcoin
// block (MsgBlock) and headers (MsgHeaders) messages.
type BlockHeader struct {
// Version of the block. This is not the same as the protocol version.
Version int32
// Hash of the previous block in the block chain.
PrevBlock chainhash.Hash
// Merkle tree reference to hash of all transactions for the block.
MerkleRoot chainhash.Hash
// Time the block was created. This is, unfortunately, encoded as a
// uint32 on the wire and therefore is limited to 2106.
Timestamp time.Time
// Difficulty target for the block.
Bits uint32
// Nonce used to generate the block.
Nonce uint32
}
// blockHeaderLen is a constant that represents the number of bytes for a block
// header.
const blockHeaderLen = 80
// BlockHash computes the block identifier hash for the given block header.
func (h *BlockHeader) BlockHash() chainhash.Hash {
// Encode the header and double sha256 everything prior to the number of
// transactions. Ignore the error returns since there is no way the
// encode could fail except being out of memory which would cause a
// run-time panic.
var buf bytes.Buffer
_ = WriteBlockHeader(&buf, 0, h)
return chainhash.DoubleHashH(buf.Bytes())
}
// ScryptHash returns the 32 byte scrypt hash of the 80 byte header
func (h *BlockHeader) ScryptHash() chainhash.Hash {
var buf bytes.Buffer
_ = WriteBlockHeader(&buf, 0, h)
scryptBytes, _ := scrypt.Key(buf.Bytes(), buf.Bytes(), 1024, 1, 1, 32)
var scryptHash [32]byte
copy(scryptHash[:], scryptBytes)
return scryptHash
}
// BtcDecode decodes r using the bitcoin protocol encoding into the receiver.
// This is part of the Message interface implementation.
// See Deserialize for decoding block headers stored to disk, such as in a
// database, as opposed to decoding block headers from the wire.
func (h *BlockHeader) BtcDecode(r io.Reader, pver uint32, enc MessageEncoding) error {
return readBlockHeader(r, pver, h)
}
// BtcEncode encodes the receiver to w using the bitcoin protocol encoding.
// This is part of the Message interface implementation.
// See Serialize for encoding block headers to be stored to disk, such as in a
// database, as opposed to encoding block headers for the wire.
func (h *BlockHeader) BtcEncode(w io.Writer, pver uint32, enc MessageEncoding) error {
return WriteBlockHeader(w, pver, h)
}
// Deserialize decodes a block header from r into the receiver using a format
// that is suitable for long-term storage such as a database while respecting
// the Version field.
func (h *BlockHeader) Deserialize(r io.Reader) error {
// At the current time, there is no difference between the wire encoding
// at protocol version 0 and the stable long-term storage format. As
// a result, make use of readBlockHeader.
return readBlockHeader(r, 0, h)
}
// Serialize encodes a block header from r into the receiver using a format
// that is suitable for long-term storage such as a database while respecting
// the Version field.
func (h *BlockHeader) Serialize(w io.Writer) error {
// At the current time, there is no difference between the wire encoding
// at protocol version 0 and the stable long-term storage format. As
// a result, make use of writeBlockHeader.
return WriteBlockHeader(w, 0, h)
}
// NewBlockHeader returns a new BlockHeader using the provided previous block
// hash, merkle root hash, difficulty bits, and nonce used to generate the
// block with defaults for the remaining fields.
func NewBlockHeader(prevHash *chainhash.Hash, merkleRootHash *chainhash.Hash,
bits uint32, nonce uint32) *BlockHeader {
// Limit the timestamp to one second precision since the protocol
// doesn't support better.
return &BlockHeader{
Version: BlockVersion,
PrevBlock: *prevHash,
MerkleRoot: *merkleRootHash,
Timestamp: time.Unix(time.Now().Unix(), 0),
Bits: bits,
Nonce: nonce,
}
}
// readBlockHeader reads a bitcoin block header from r. See Deserialize for
// decoding block headers stored to disk, such as in a database, as opposed to
// decoding from the wire.
func readBlockHeader(r io.Reader, pver uint32, bh *BlockHeader) error {
err := readElements(r, &bh.Version, &bh.PrevBlock, &bh.MerkleRoot,
(*uint32Time)(&bh.Timestamp), &bh.Bits, &bh.Nonce)
if err != nil {
return err
}
return nil
}
// writeBlockHeader writes a bitcoin block header to w. See Serialize for
// encoding block headers to be stored to disk, such as in a database, as
// opposed to encoding for the wire.
func WriteBlockHeader(w io.Writer, pver uint32, bh *BlockHeader) error {
sec := uint32(bh.Timestamp.Unix())
err := writeElements(w, bh.Version, &bh.PrevBlock, &bh.MerkleRoot,
sec, bh.Bits, bh.Nonce)
if err != nil {
return err
}
return nil
}