bitcore/Block.js at master · SomeoneWeird/bitcore · GitHub

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require('classtool');

function spec(b) {

var util = b.util || require('./util/util');

var Debug1 = b.Debug1 || function() {};

var Script = b.Script || require('./Script').class();

var Bignum = b.Bignum || require('bignum');

var Binary = b.Binary || require('binary');

var Step = b.Step || require('step');

var buffertools = b.buffertools || require('buffertools');

var Transaction = b.Transaction || require('./Transaction').class();

var TransactionIn = Transaction.In;

var TransactionOut = Transaction.Out;

var COINBASE_OP = Transaction.COINBASE_OP;

var VerificationError = b.VerificationError || require('./util/error').VerificationError;

var BlockRules = {

maxTimeOffset: 2 * 60 * 60, // How far block timestamps can be into the future

largestHash: Bignum(2).pow(256)

};

function Block(data)

{

if ("object" !== typeof data) {

data = {};

}

this.hash = data.hash || null;

this.prev_hash = data.prev_hash || util.NULL_HASH;

this.merkle_root = data.merkle_root || util.NULL_HASH;

this.timestamp = data.timestamp || 0;

this.bits = data.bits || 0;

this.nonce = data.nonce || 0;

this.version = data.version || 0;

this.height = data.height || 0;

this.size = data.size || 0;

this.active = data.active || false;

this.chainWork = data.chainWork || util.EMPTY_BUFFER;

this.txs = data.txs || [];

}

Block.prototype.getHeader = function getHeader() {

var buf = new Buffer(80);

var ofs = 0;

buf.writeUInt32LE(this.version, ofs); ofs += 4;

this.prev_hash.copy(buf, ofs); ofs += 32;

this.merkle_root.copy(buf, ofs); ofs += 32;

buf.writeUInt32LE(this.timestamp, ofs); ofs += 4;

buf.writeUInt32LE(this.bits, ofs); ofs += 4;

buf.writeUInt32LE(this.nonce, ofs); ofs += 4;

return buf;

};

Block.prototype.parse = function parse(parser, headerOnly) {

this.version = parser.word32le();

this.prev_hash = parser.buffer(32);

this.merkle_root = parser.buffer(32);

this.timestamp = parser.word32le();

this.bits = parser.word32le();

this.nonce = parser.word32le();

this.txs = [];

this.size = 0;

if (headerOnly)

return;

var txCount = parser.varInt();

for (var i = 0; i < txCount; i++) {

var tx = new Transaction();

tx.parse(parser);

this.txs.push(tx);

}

};

Block.prototype.calcHash = function calcHash() {

var header = this.getHeader();

return util.twoSha256(header);

};

Block.prototype.checkHash = function checkHash() {

if (!this.hash || !this.hash.length) return false;

return buffertools.compare(this.calcHash(), this.hash) == 0;

};

Block.prototype.getHash = function getHash() {

if (!this.hash || !this.hash.length) this.hash = this.calcHash();

return this.hash;

};

Block.prototype.checkProofOfWork = function checkProofOfWork() {

var target = util.decodeDiffBits(this.bits);

// TODO: Create a compare method in node-buffertools that uses the correct

// endian so we don't have to reverse both buffers before comparing.

buffertools.reverse(this.hash);

if (buffertools.compare(this.hash, target) > 0) {

throw new VerificationError('Difficulty target not met');

}

// Return the hash to its normal order

buffertools.reverse(this.hash);

return true;

};

/**

* Returns the amount of work that went into this block.

* Work is defined as the average number of tries required to meet this

* block's difficulty target. For example a target that is greater than 5%

* of all possible hashes would mean that 20 "work" is required to meet it.

Block.prototype.getWork = function getWork() {

var target = util.decodeDiffBits(this.bits, true);

return BlockRules.largestHash.div(target.add(1));

};

Block.prototype.checkTimestamp = function checkTimestamp() {

var currentTime = new Date().getTime() / 1000;

if (this.timestamp > currentTime + BlockRules.maxTimeOffset) {

throw new VerificationError('Timestamp too far into the future');

}

return true;

};

Block.prototype.checkTransactions = function checkTransactions(txs) {

if (!Array.isArray(txs) || txs.length <= 0) {

throw new VerificationError('No transactions');

}

if (!txs[0].isCoinBase()) {

throw new VerificationError('First tx must be coinbase');

}

for (var i = 1; i < txs.length; i++) {

if (txs[i].isCoinBase()) {

throw new VerificationError('Tx index '+i+' must not be coinbase');

}

return true;

};

/**

* Build merkle tree.

* Ported from Java. Original code: BitcoinJ by Mike Hearn

Block.prototype.getMerkleTree = function getMerkleTree(txs) {

// The merkle hash is based on a tree of hashes calculated from the transactions:

// merkleHash

// /\

// / \

// A B

// / \ / \

// tx1 tx2 tx3 tx4

// Basically transactions are hashed, then the hashes of the transactions are hashed

// again and so on upwards into the tree. The point of this scheme is to allow for

// disk space savings later on.

// This function is a direct translation of CBlock::BuildMerkleTree().

if (txs.length == 0) {

return [util.NULL_HASH.slice(0)];

}

// Start by adding all the hashes of the transactions as leaves of the tree.

var tree = txs.map(function (tx) {

return tx instanceof Transaction ? tx.getHash() : tx;

});

var j = 0;

// Now step through each level ...

for (var size = txs.length; size > 1; size = Math.floor((size + 1) / 2)) {

// and for each leaf on that level ..

for (var i = 0; i < size; i += 2) {

var i2 = Math.min(i + 1, size - 1);

var a = tree[j + i];

var b = tree[j + i2];

tree.push(util.twoSha256(Buffer.concat([a,b])));

}

j += size;

}

return tree;

};

Block.prototype.calcMerkleRoot = function calcMerkleRoot(txs) {

var tree = this.getMerkleTree(txs);

return tree[tree.length - 1];

};

Block.prototype.checkMerkleRoot = function checkMerkleRoot(txs) {

if (!this.merkle_root || !this.merkle_root.length) {

throw new VerificationError('No merkle root');

}

if (buffertools.compare(this.calcMerkleRoot(), this.merkle_root) == 0) {

throw new VerificationError('Merkle root incorrect');

}

return true;

};

Block.prototype.checkBlock = function checkBlock(txs) {

if (!this.checkHash()) {

throw new VerificationError("Block hash invalid");

}

this.checkProofOfWork();

this.checkTimestamp();

if (txs) {

this.checkTransactions(txs);

if (!this.checkMerkleRoot(txs)) {

throw new VerificationError("Merkle hash invalid");

}

return true;

};

Block.getBlockValue = function getBlockValue(height) {

var subsidy = Bignum(50).mul(util.COIN);

subsidy = subsidy.div(Bignum(2).pow(Math.floor(height / 210000)));

return subsidy;

};

Block.prototype.getBlockValue = function getBlockValue() {

return Block.getBlockValue(this.height);

};

Block.prototype.toString = function toString() {

return "<Block " + util.formatHashAlt(this.hash) + " height="+this.height+">";

};

/**

* Initializes some properties based on information from the parent block.

Block.prototype.attachTo = function attachTo(parent) {

this.height = parent.height + 1;

this.setChainWork(parent.getChainWork().add(this.getWork()));

};

Block.prototype.setChainWork = function setChainWork(chainWork) {

if (Buffer.isBuffer(chainWork)) {

// Nothing to do

} else if ("function" === typeof chainWork.toBuffer) { // duck-typing bignum

chainWork = chainWork.toBuffer();

} else {

throw new Error("Block.setChainWork(): Invalid datatype");

}

this.chainWork = chainWork;

};

Block.prototype.getChainWork = function getChainWork() {

return Bignum.fromBuffer(this.chainWork);

};

/**

* Compares the chainWork of two blocks.

Block.prototype.moreWorkThan = function moreWorkThan(otherBlock) {

return this.getChainWork().cmp(otherBlock.getChainWork()) > 0;

};

/**

* Returns the difficulty target for the next block after this one.

Block.prototype.getNextWork =

function getNextWork(blockChain, nextBlock, callback) {

var self = this;

var powLimit = blockChain.getMinDiff();

var powLimitTarget = util.decodeDiffBits(powLimit, true);

var targetTimespan = blockChain.getTargetTimespan();

var targetSpacing = blockChain.getTargetSpacing();

var interval = targetTimespan / targetSpacing;

if (this.height == 0) {

callback(null, this.bits);

}

if ((this.height+1) % interval !== 0) {

if (blockChain.isTestnet()) {

// Special testnet difficulty rules

var lastBlock = blockChain.getTopBlock();

// If the new block's timestamp is more than 2 * 10 minutes

// then allow mining of a min-difficulty block.

if (nextBlock.timestamp > this.timestamp + targetSpacing*2) {

callback(null, powLimit);

} else {

// Return last non-"special-min-difficulty" block

if (this.bits != powLimit) {

// Current block is non-min-diff

callback(null, this.bits);

} else {

// Recurse backwards until a non min-diff block is found.

function lookForLastNonMinDiff(block, callback) {

try {

if (block.height > 0 &&

block.height % interval !== 0 &&

block.bits == powLimit) {

blockChain.getBlockByHeight(

block.height - 1,

function (err, lastBlock) {

try {

if (err) throw err;

lookForLastNonMinDiff(lastBlock, callback);

} catch (err) {

callback(err);

}

);

} else {

callback(null, block.bits);

}

} catch (err) {

callback(err);

}

};

lookForLastNonMinDiff(this, callback);

}

} else {

// Not adjustment interval, next block has same difficulty

callback(null, this.bits);

}

} else {

// Get the first block from the old difficulty period

blockChain.getBlockByHeight(

this.height - interval + 1,

function (err, lastBlock) {

try {

if (err) throw err;

// Determine how long the difficulty period really took

var actualTimespan = self.timestamp - lastBlock.timestamp;

// There are some limits to how much we will adjust the difficulty in

// one step

if (actualTimespan < targetTimespan/4) {

actualTimespan = targetTimespan/4;

}

if (actualTimespan > targetTimespan*4) {

actualTimespan = targetTimespan*4;

}

var oldTarget = util.decodeDiffBits(self.bits, true);

var newTarget = oldTarget.mul(actualTimespan).div(targetTimespan);

if (newTarget.cmp(powLimitTarget) > 0) {

newTarget = powLimitTarget;

}

Debug1('Difficulty retarget (target='+targetTimespan +

', actual='+actualTimespan+')');

Debug1('Before: '+oldTarget.toBuffer().toString('hex'));

Debug1('After: '+newTarget.toBuffer().toString('hex'));

callback(null, util.encodeDiffBits(newTarget));

} catch (err) {

callback(err);

}

);

}

};

var medianTimeSpan = 11;

Block.prototype.getMedianTimePast =

function getMedianTimePast(blockChain, callback)

{

var self = this;

Step(

function getBlocks() {

var heights = [];

for (var i = 0, m = medianTimeSpan; i < m && (self.height - i) >= 0; i++) {

heights.push(self.height - i);

}

blockChain.getBlocksByHeights(heights, this);

function calcMedian(err, blocks) {

if (err) throw err;

var timestamps = blocks.map(function (block) {

if (!block) {

throw new Error("Prior block missing, cannot calculate median time");

}

return +block.timestamp;

});

// Sort timestamps

timestamps = timestamps.sort();

// Return median timestamp

this(null, timestamps[Math.floor(timestamps.length/2)]);

callback

);

};

Block.prototype.verifyChild =

function verifyChild(blockChain, child, callback)

{

var self = this;

Step(

function getExpectedDifficulty() {

self.getNextWork(blockChain, child, this);

function verifyExpectedDifficulty(err, nextWork) {

if (err) throw err;

if (+child.bits !== +nextWork) {

throw new VerificationError("Incorrect proof of work '"+child.bits+"',"+

" should be '"+nextWork+"'.");

}

this();

function getMinimumTimestamp(err) {

if (err) throw err;

self.getMedianTimePast(blockChain, this);

function verifyTimestamp(err, medianTimePast) {

if (err) throw err;

if (child.timestamp <= medianTimePast) {

throw new VerificationError("Block's timestamp is too early");

}

this();

callback

);

};

Block.prototype.createCoinbaseTx =

function createCoinbaseTx(beneficiary)

{

var tx = new Transaction();

tx.ins.push(new TransactionIn({

s: util.EMPTY_BUFFER,

q: 0xffffffff,

o: COINBASE_OP

}));

tx.outs.push(new TransactionOut({

v: util.bigIntToValue(this.getBlockValue()),

s: Script.createPubKeyOut(beneficiary).getBuffer()

}));

return tx;

};

Block.prototype.prepareNextBlock =

function prepareNextBlock(blockChain, beneficiary, time, callback)

{

var self = this;

var newBlock = new Block();

Step(

function getMedianTimePastStep() {

self.getMedianTimePast(blockChain, this);

function getNextWorkStep(err, medianTimePast) {

if (err) throw err;

if (!time) {

// TODO: Use getAdjustedTime for the second timestamp

time = Math.max(medianTimePast+1,

Math.floor(new Date().getTime() / 1000));

}

self.getNextWork(blockChain, newBlock, this);

function applyNextWorkStep(err, nextWork) {

if (err) throw err;

newBlock.bits = nextWork;

this(null);

function miscStep(err) {

if (err) throw err;

newBlock.version = 1;

newBlock.timestamp = time;

newBlock.prev_hash = self.getHash().slice(0);

newBlock.height = self.height+1;

// Create coinbase transaction

var txs = [];

var tx = newBlock.createCoinbaseTx(beneficiary);

txs.push(tx);

newBlock.merkle_root = newBlock.calcMerkleRoot(txs);

// Return reference to (unfinished) block

this(null, {block: newBlock, txs: txs});

callback

);

};

Block.prototype.mineNextBlock =

function mineNextBlock(blockChain, beneficiary, time, miner, callback)

{

this.prepareNextBlock(blockChain, beneficiary, time, function (err, data) {

try {

if (err) throw err;

var newBlock = data.block;

var txs = data.txs;

newBlock.solve(miner, function (err, nonce) {

newBlock.nonce = nonce;

// Make sure hash is cached

newBlock.getHash();

callback(err, newBlock, txs);

});

// Return reference to (unfinished) block

return newBlock;

} catch (e) {

callback(e);

}

});

};

Block.prototype.solve = function solve(miner, callback) {

var header = this.getHeader();

var target = util.decodeDiffBits(this.bits);

miner.solve(header, target, callback);

};

/**

* Returns an object with the same field names as jgarzik's getblock patch.

Block.prototype.getStandardizedObject =

function getStandardizedObject(txs)

{

var block = {

hash: util.formatHashFull(this.getHash()),

version: this.version,

prev_block: util.formatHashFull(this.prev_hash),

mrkl_root: util.formatHashFull(this.merkle_root),

time: this.timestamp,

bits: this.bits,

nonce: this.nonce,

height: this.height

};

if (txs) {

var mrkl_tree = this.getMerkleTree(txs).map(function (buffer) {

return util.formatHashFull(buffer);

});

block.mrkl_root = mrkl_tree[mrkl_tree.length - 1];

block.n_tx = txs.length;

var totalSize = 80; // Block header

totalSize += util.getVarIntSize(txs.length); // txn_count

txs = txs.map(function (tx) {

tx = tx.getStandardizedObject();

totalSize += tx.size;

return tx;

});

block.size = totalSize;

block.tx = txs;

block.mrkl_tree = mrkl_tree;

} else {

block.size = this.size;

}

return block;

};

return Block;

};

module.defineClass(spec);

bitcore/Block.js at master · SomeoneWeird/bitcore · GitHub

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