fcoin/lib/bcoin/chain.js
Christopher Jeffrey 997f0acbb0 more refactoring.
2016-02-16 16:13:34 -08:00

1237 lines
30 KiB
JavaScript

/**
* chain.js - blockchain management for bcoin
* Copyright (c) 2014-2015, Fedor Indutny (MIT License)
* https://github.com/indutny/bcoin
*/
var inherits = require('inherits');
var EventEmitter = require('events').EventEmitter;
var request = require('request');
var bcoin = require('../bcoin');
var bn = require('bn.js');
var constants = bcoin.protocol.constants;
var network = bcoin.protocol.network;
var utils = bcoin.utils;
var assert = utils.assert;
var fs = bcoin.fs;
/**
* Chain
*/
function Chain(options) {
if (!(this instanceof Chain))
return new Chain(options);
EventEmitter.call(this);
if (!options)
options = {};
this.options = options;
if (this.options.debug)
bcoin.debug = this.options.debug;
this.db = new bcoin.chaindb(this);
this.heightLookup = {};
this.request = new utils.RequestCache();
this.loading = false;
this.tip = null;
this.mempool = options.mempool;
this.blockdb = options.blockdb;
this.orphan = {
map: {},
bmap: {},
count: 0,
size: 0
};
this._saveEntry(bcoin.chainblock.fromJSON(this, {
hash: network.genesis.hash,
version: network.genesis.version,
prevBlock: network.genesis.prevBlock,
merkleRoot: network.genesis.merkleRoot,
ts: network.genesis.ts,
bits: network.genesis.bits,
nonce: network.genesis.nonce,
height: 0
}), true);
Chain.global = this;
this._init();
}
inherits(Chain, EventEmitter);
Chain.codes = {
okay: 0,
newOrphan: 1,
knownOrphan: 2,
forked: 3,
invalid: 4,
badCheckpoint: 4,
unchanged: 5
};
Chain.messages = {
0: 'Block was added successfully',
1: 'Block is a new orphan',
2: 'Block is a known orphan',
3: 'Block is a greater fork',
4: 'Block verification failed',
5: 'Block does not match checkpoint',
6: 'Chain is unchanged'
};
Chain.msg = function msg(code) {
return Chain.messages[code] || 'Unknown';
};
Chain.prototype._init = function _init() {
var self = this;
this.loading = true;
utils.debug('Chain is loading.');
this._preload(function(err, start) {
if (err) {
utils.debug('Preloading chain failed.');
utils.debug('Reason: %s', err.message);
}
utils.nextTick(function() {
var count = self.db.count();
var i = start || 1;
var lastEntry;
utils.debug('Starting chain load at height: %s', i);
function done(height) {
if (height != null) {
utils.debug(
'Blockchain is corrupt after height %d. Resetting.',
height);
self.resetHeight(height);
} else {
utils.debug('Chain successfully loaded.');
}
self.loading = false;
self.emit('load');
}
(function next() {
if (i >= count)
return done();
self.db.getAsync(i, function(err, entry) {
if (err)
throw err;
// Do some paranoid checks.
if (lastEntry && entry.prevBlock !== lastEntry.hash)
return done(Math.max(0, i - 2));
lastEntry = entry;
self._saveEntry(entry);
i += 1;
next();
});
})();
});
});
};
// Stream headers from electrum.org for quickly
// preloading the chain. Electrum.org stores
// headers in the standard block header format,
// but they do not store chainwork, so we have
// to calculate it ourselves.
Chain.prototype._preload = function _preload(callback) {
var self = this;
var url = 'https://headers.electrum.org/blockchain_headers';
var chainHeight, buf, height, stream;
if (!this.options.preload)
return callback();
if (network.type !== 'main')
return callback(new Error('Electrum.org only offers `main` headers.'));
utils.debug('Loading %s', url);
stream = request.get(url);
chainHeight = this.db.count() - 1;
height = 0;
buf = {
data: [],
size: 0
};
stream.on('response', function(res) {
if (res.statusCode >= 400) {
stream.destroy();
return callback(new Error('Bad response code: ' + res.statusCode));
}
});
stream.on('error', function(err) {
var start = Math.max(0, height - 2);
self.resetHeight(start);
return callback(err, start + 1);
});
stream.on('data', function(data) {
var blocks = [];
var need = 80 - buf.size;
var i, lastEntry;
while (data.length >= need) {
buf.data.push(data.slice(0, need));
blocks.push(Buffer.concat(buf.data));
buf.data.length = 0;
buf.size = 0;
data = data.slice(need);
need = 80 - buf.size;
}
if (data.length > 0) {
assert(data.length < 80);
buf.data.push(data);
buf.size += data.length;
}
if (blocks.length === 0)
return;
blocks.forEach(function(data) {
var entry = bcoin.chainblock.fromRaw(self, height, data);
var block = bcoin.block(entry, 'headers');
var start;
// Do some paranoid checks.
if (lastEntry && entry.prevBlock !== lastEntry.hash) {
start = Math.max(0, height - 2);
stream.destroy();
self.resetHeight(start);
return callback(new Error('Corrupt headers.'), start + 1);
}
// Verify the block headers. We don't want to
// trust an external centralized source completely.
// For very paranoid but slower validation:
// if (!block.verify() || !block.verifyContext()) {
if (!block.verify()) {
start = Math.max(0, height - 2);
stream.destroy();
self.resetHeight(start);
return callback(new Error('Bad headers.'), start + 1);
}
lastEntry = entry;
delete entry.chainwork;
entry.chainwork = entry.getChainwork();
// Skip the genesis block in case
// it ends up being corrupt.
if (height === 0) {
height++;
return;
}
// Don't write blocks we already have
// (bad for calculating chainwork).
// self._saveEntry(entry, height > chainHeight);
self._saveEntry(entry, true);
height++;
if ((height + 1) % 50000 === 0)
utils.debug('Received %d headers from electrum.org.', height + 1);
});
});
stream.on('end', function() {
return callback(null, height + 1);
});
};
Chain.prototype._saveBlock = function _saveBlock(block, callback) {
var self = this;
if (!this.blockdb)
return callback();
this.blockdb.block.saveBlock(block, function(err) {
if (err)
return callback(err);
if (self.mempool)
self.mempool.addBlock(block);
return callback();
});
};
Chain.prototype._removeBlock = function _removeBlock(tip, callback) {
var self = this;
if (!this.blockdb)
return callback();
this.blockdb.removeBlock(tip, function(err, block) {
if (err)
return callback(err);
if (!block)
return callback();
if (self.mempool)
self.mempool.removeBlock(block);
self.emit('reorg block', block.hash('hex'));
block.txs.forEach(function(tx) {
self.emit('reorg tx', tx.hash('hex'));
});
return callback();
});
};
Chain.prototype._verifyContext = function _verifyContext(block, prev, callback) {
var self = this;
var flags;
flags = this._verify(block, prev);
if (flags === false)
return callback(null, false);
this._checkDuplicates(block, prev, function(err, result) {
if (err)
return callback(err);
if (!result)
return callback(null, false);
self._checkInputs(block, prev, flags, function(err, result) {
if (err)
return callback(err);
if (!result)
return callback(null, false);
return callback(null, true);
});
});
};
Chain.prototype._verify = function _verify(block, prev) {
var flags = constants.flags.MANDATORY_VERIFY_FLAGS;
var sigops = 0;
var height, ts, i, tx, cb, coinbaseHeight, medianTime, locktimeMedian;
// Skip the genesis block
if (block.isGenesis())
return flags;
// Ensure it's not an orphan
if (!prev) {
utils.debug('Block has no previous entry: %s', block.rhash);
return false;
}
height = prev.height + 1;
medianTime = prev.getMedianTime();
// Ensure the timestamp is correct
if (block.ts <= medianTime) {
utils.debug('Block time is lower than median: %s', block.rhash);
return false;
}
// Ensure the miner's target is equal to what we expect
if (block.bits !== block.chain.getTarget(prev, block)) {
utils.debug('Block is using wrong target: %s', block.rhash);
return false;
}
// Only allow version 2 blocks (coinbase height)
// once the majority of blocks are using it.
if (block.version < 2 && prev.isOutdated(2)) {
utils.debug('Block is outdated (v2): %s', block.rhash);
return false;
}
// Only allow version 3 blocks (sig validation)
// once the majority of blocks are using it.
if (block.version < 3 && prev.isOutdated(3)) {
utils.debug('Block is outdated (v3): %s', block.rhash);
return false;
}
// Only allow version 4 blocks (checklocktimeverify)
// once the majority of blocks are using it.
if (block.version < 4 && prev.isOutdated(4)) {
utils.debug('Block is outdated (v4): %s', block.rhash);
return false;
}
// Only allow version 8 blocks (locktime median past)
// once the majority of blocks are using it.
// if (block.version < 8 && prev.isOutdated(8)) {
// utils.debug('Block is outdated (v8): %s', block.rhash);
// return false;
// }
// Make sure the height contained in the coinbase is correct.
if (block.version >= 2 && prev.isUpgraded(2))
coinbaseHeight = true;
// Signature validation is now enforced (bip66)
if (block.version >= 3 && prev.isUpgraded(3))
flags |= constants.flags.VERIFY_DERSIG;
// CHECKLOCKTIMEVERIFY is now usable (bip65)
if (block.version >= 4 && prev.isUpgraded(4))
flags |= constants.flags.VERIFY_CHECKLOCKTIMEVERIFY;
// Use nLockTime median past (bip113)
// https://github.com/btcdrak/bips/blob/d4c9a236ecb947866c61aefb868b284498489c2b/bip-0113.mediawiki
// Support version bits:
// https://gist.github.com/sipa/bf69659f43e763540550
// http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-August/010396.html
// if (block.version >= 8 && prev.isUpgraded(8))
// locktimeMedian = true;
// Can't verify any further when merkleblock or headers.
if (block.subtype !== 'block')
return flags;
// Make sure the height contained in the coinbase is correct.
if (coinbaseHeight) {
cb = bcoin.script.getCoinbaseData(block.txs[0].inputs[0].script);
// Make sure the coinbase is parseable.
if (!cb) {
utils.debug('Block has malformed coinbase: %s', block.rhash);
return false;
}
// Make sure coinbase height is equal to the actual height.
if (cb.height !== height) {
utils.debug('Block has bad coinbase height: %s', block.rhash);
return false;
}
}
// Get timestamp for tx.isFinal().
ts = locktimeMedian ? medianTime : block.ts;
// Check all transactions
for (i = 0; i < block.txs.length; i++) {
tx = block.txs[i];
// Transactions must be finalized with
// regards to nSequence and nLockTime.
if (!tx.isFinal(height, ts)) {
utils.debug('TX is not final: %s (%s)', block.rhash, i);
return false;
}
// Check for tx sigops limits
// Bitcoind does not check for this when accepting
// a block even though it probably should.
// if (tx.getSigops(true) > constants.script.maxTxSigops) {
// // Block 71036 abused checksig to
// // include a huge number of sigops.
// utils.debug('Block TX has too many sigops: %s', block.rhash);
// if (!(network.type === 'main' && height === 71036))
// return false;
// }
// Check for block sigops limits
// Start counting P2SH sigops once block
// timestamps reach March 31st, 2012.
if (block.ts >= constants.block.bip16time)
sigops += tx.getSigops(true);
else
sigops += tx.getSigops();
if (sigops > constants.script.maxBlockSigops) {
utils.debug('Block has too many sigops: %s', block.rhash);
return false;
}
}
return flags;
};
Chain.prototype._checkDuplicates = function _checkDuplicates(block, prev, callback) {
var height = prev.height + 1;
var pending = block.txs.length;
var called;
if (!this.blockdb || block.subtype !== 'block')
return callback(null, true);
if (block.isGenesis())
return callback(null, true);
assert(pending);
function done(err, result) {
if (called)
return;
called = true;
callback(err, result);
}
// Check all transactions
block.txs.forEach(function(tx) {
var hash = tx.hash('hex');
// BIP30 - Ensure there are no duplicate txids
self.blockdb.hasTX(hash, function(err, result) {
if (called)
return;
if (err)
return done(err);
// Blocks 91842 and 91880 created duplicate
// txids by using the same exact output script
// and extraNonce.
if (result) {
utils.debug('Block is overwriting txids: %s', block.rhash);
if (!(network.type === 'main' && (height === 91842 || height === 91880)))
return done(null, false);
}
if (!--pending)
return done(null, true);
});
});
};
Chain.prototype._checkInputs = function _checkInputs(block, prev, flags, callback) {
var height = prev.height + 1;
if (!this.blockdb || block.subtype !== 'block')
return callback(null, true);
if (block.isGenesis())
return callback(null, true);
// If we are an ancestor of a checkpoint, we can
// skip the input verification.
if (height < network.checkpoints.lastHeight && !network.checkpoints[height])
return callback(null, true);
this.blockdb.fillCoins(block.txs, function(err) {
var i, j, input, hash;
if (err)
return callback(err);
// Check all transactions
for (i = 0; i < block.txs.length; i++) {
tx = blocks.txs[i];
hash = tx.hash('hex');
for (j = 0; j < tx.inputs.length; j++) {
input = tx.inputs[j];
// Coinbases do not have prevouts
if (tx.isCoinbase())
continue;
// Ensure tx is not double spending an output
if (!input.output) {
utils.debug('Block is using spent inputs: %s (tx: %s, output: %s)',
block.rhash, tx.rhash,
input.prevout.rhash + '/' + input.prevout.index);
return callback(null, false);
}
// Verify the scripts
if (!tx.verify(j, true, flags)) {
utils.debug('Block has invalid inputs: %s', block.rhash);
return callback(null, false);
}
}
}
return callback(null, true);
});
};
Chain.prototype._addEntry = function _addEntry(entry, block, callback) {
var self = this;
var existing;
callback = utils.asyncify(callback);
// Already added
if (this.heightLookup[entry.hash] != null) {
assert(this.heightLookup[entry.hash] === entry.height);
return callback(null, Chain.codes.unchanged);
}
// Duplicate height (do a sync call here since this is cached)
existing = this.db.get(entry.height);
if (existing && existing.hash === entry.hash)
return callback(null, Chain.codes.unchanged);
this._saveBlock(block, function(err) {
if (err)
return callback(err);
self._saveEntry(entry, true, function(err) {
if (err)
return callback(err);
return callback(null, Chain.codes.okay);
});
});
};
Chain.prototype._saveEntry = function _saveEntry(entry, save, callback) {
this.heightLookup[entry.hash] = entry.height;
if (!this.tip || entry.height > this.tip.height) {
this.tip = entry;
this.emit('tip', this.tip);
}
if (save)
this.db.save(entry, callback);
};
Chain.prototype.resetLastCheckpoint = function resetLastCheckpoint(height) {
var heights = Object.keys(network.checkpoints).sort();
var index = heights.indexOf(height) - 1;
var checkpoint = network.checkpoint[index];
assert(index >= 0);
assert(checkpoint);
// This is the safest way to do it, the other
// possibility is to simply reset ignore the
// bad checkpoint block. The likelihood of
// someone carrying on an entire fork between
// to checkpoints is absurd, so this is
// probably _a lot_ of work for nothing.
this.resetHeight(checkpoint.height);
};
Chain.prototype.resetHeight = function resetHeight(height) {
var self = this;
var count = this.db.count();
var i, existing;
assert(height < count);
// Reset the orphan map completely. There may
// have been some orphans on a forked chain we
// no longer need.
this.orphan.map = {};
this.orphan.bmap = {};
this.orphan.count = 0;
this.orphan.size = 0;
for (i = height + 1; i < count; i++) {
existing = this.db.get(i);
assert(existing);
delete this.heightLookup[existing.hash];
this.db.remove(i);
}
this.tip = this.db.get(height);
this.emit('tip', this.tip);
};
Chain.prototype.resetTime = function resetTime(ts) {
var entry = this.byTime(ts);
if (!entry)
return;
return this.resetHeight(entry.height);
};
Chain.prototype.add = function add(initial, peer, callback) {
var self = this;
var code = Chain.codes.unchanged;
var total = 0;
callback = utils.asyncify(callback);
if (this._locked)
return callback(null, total);
(function next(block) {
var hash = block.hash('hex');
var prevHash = block.prevBlock;
var prevHeight, entry, existing, checkpoint, prev;
// Find the previous block height/index.
prevHeight = self.heightLookup[prevHash];
// Validate the block we want to add.
// This is only necessary for new
// blocks coming in, not the resolving
// orphans.
if (block === initial && !block.verify()) {
code = Chain.codes.invalid;
self.emit('invalid', {
height: prevHeight + 1,
hash: hash
}, peer);
return done(null, code);
}
// If the block is already known to be
// an orphan, ignore it.
if (self.orphan.map[prevHash]) {
// If the orphan chain forked, simply
// reset the orphans and find a new peer.
if (self.orphan.map[prevHash].hash('hex') !== hash) {
self.orphan.map = {};
self.orphan.bmap = {};
self.orphan.count = 0;
self.orphan.size = 0;
self.emit('fork', {
height: -1,
expected: self.orphan.map[prevHash].hash('hex'),
received: hash,
checkpoint: false
}, peer);
code = Chain.codes.forked;
return done(null, code);
}
code = Chain.codes.knownOrphan;
return done(null, code);
}
// If previous block wasn't ever seen,
// add it current to orphans and break.
if (prevHeight == null) {
self.orphan.count++;
self.orphan.size += block.getSize();
self.orphan.map[prevHash] = block;
self.orphan.bmap[hash] = block;
code = Chain.codes.newOrphan;
total++;
return done(null, code);
}
// Create a new chain entry.
entry = new bcoin.chainblock(self, {
hash: hash,
version: block.version,
prevBlock: prevHash,
merkleRoot: block.merkleRoot,
ts: block.ts,
bits: block.bits,
nonce: block.nonce,
height: prevHeight + 1
});
// Fork at checkpoint
// Block did not match the checkpoint. The
// chain could be reset to the last sane
// checkpoint, but it really isn't necessary,
// so we don't do it. The misbehaving peer has
// been killed and hopefully we find a peer
// who isn't trying to fool us.
checkpoint = network.checkpoints[entry.height];
if (checkpoint) {
self.emit('checkpoint', entry.height, entry.hash, checkpoint);
if (hash !== checkpoint) {
// Resetting to the last checkpoint _really_ isn't
// necessary (even bitcoind doesn't do it), but it
// could be used if you want to be on the overly
// safe (see: paranoid) side.
// this.resetLastCheckpoint(entry.height);
code = Chain.codes.badCheckpoint;
self.emit('fork', {
height: entry.height,
expected: network.checkpoints[entry.height],
received: entry.hash,
checkpoint: true
});
return done(null, code);
}
}
// See if the entry already exists.
existing = self.db.get(entry.height);
// Entry already exists.
if (existing) {
// We already have this block. Do regular
// orphan resolution (won't do anything).
if (existing.hash === hash)
return handleOrphans();
// A valid block with an already existing
// height came in, that spells fork. We
// don't store by hash so we can't compare
// chainworks. We reset the chain, find a
// new peer, and wait to see who wins.
assert(self.heightLookup[entry.hash] == null);
// The tip has more chainwork, it is a
// higher height than the entry. This is
// not an alternate tip. Ignore it.
if (self.tip.chainwork.cmp(entry.chainwork) > 0) {
code = Chain.codes.unchanged;
return done(null, code);
}
// The block has equal chainwork (an
// alternate tip). Reset the chain, find
// a new peer, and wait to see who wins.
self._locked = true;
return self._removeBlock(existing.hash, function(err) {
self._locked = false;
if (err)
return done(err);
self.resetHeight(entry.height - 1);
self.emit('fork', {
height: prevHeight + 1,
expected: existing.hash,
received: hash,
checkpoint: false
}, peer);
code = Chain.codes.forked;
return done(null, code);
});
}
// Add entry if we do not have it.
assert(self.heightLookup[entry.hash] == null);
// Lookup previous entry.
prev = self.db.get(prevHeight);
assert(prev);
// Do "contextual" verification on our block
// now that we're certain its previous
// block is in the chain.
self._verifyContext(block, prev, function(err, verified) {
if (err)
return done(err);
if (!verified) {
code = Chain.codes.invalid;
self.emit('invalid', {
height: prevHeight + 1,
hash: hash
}, peer);
return done(null, code);
}
// Update the block height
block.height = entry.height;
block.txs.forEach(function(tx) {
tx.height = entry.height;
});
// Attempt to add block to the chain index.
self._addEntry(entry, block, function(err, code_) {
if (err)
return done(err);
code = code_;
// Result should never be `unchanged` since
// we already verified there were no
// duplicate heights, etc.
assert(code !== Chain.codes.unchanged);
// Should always be okay.
assert(code === Chain.codes.okay);
// Keep track of the number of blocks we
// added and the number of orphans resolved.
total++;
// Emit our block (and potentially resolved
// orphan) so the programmer can save it.
self.emit('block', block, peer);
self.emit('entry', entry);
if (block !== initial)
self.emit('resolved', block, peer);
// Fullfill request
self.request.fullfill(hash, block);
handleOrphans();
});
});
function handleOrphans() {
if (!self.orphan.map[hash])
return done(null, code);
// An orphan chain was found, start resolving.
block = self.orphan.map[hash];
delete self.orphan.bmap[block.hash('hex')];
delete self.orphan.map[hash];
self.orphan.count--;
self.orphan.size -= block.getSize();
next(block);
}
})(initial);
function done(err, code) {
// Failsafe for large orphan chains. Do not
// allow more than 20mb stored in memory.
if (self.orphan.size > 20971520) {
Object.keys(self.orphan.bmap).forEach(function(hash) {
self.emit('unresolved', self.orphan.bmap[hash], peer);
});
self.orphan.map = {};
self.orphan.bmap = {};
self.orphan.count = 0;
self.orphan.size = 0;
}
if (code !== Chain.codes.okay) {
if (!(self.options.multiplePeers && code === Chain.codes.newOrphan))
utils.debug('Chain Error: %s', Chain.msg(code));
}
if (err)
return callback(err);
return callback(null, total);
}
};
Chain.prototype.has = function has(hash) {
if (this.hasBlock(hash))
return true;
if (this.hasOrphan(hash))
return true;
return false;
};
Chain.prototype.byHeight = function byHeight(height) {
if (height == null)
return;
return this.db.get(height);
};
Chain.prototype.byHash = function byHash(hash) {
if (utils.isBuffer(hash))
hash = utils.toHex(hash);
else if (hash.hash)
hash = hash.hash('hex');
return this.byHeight(this.heightLookup[hash]);
};
Chain.prototype.byTime = function byTime(ts) {
var start = 0;
var end = this.db.count();
var pos, delta, entry;
if (ts >= this.tip.ts)
return this.tip;
// Do a binary search for a block
// mined within an hour of the
// timestamp.
while (start < end) {
pos = (start + end) >> 1;
entry = this.db.get(pos);
delta = Math.abs(ts - entry.ts);
if (delta <= 60 * 60)
return entry;
if (ts < entry.ts) {
end = pos;
} else {
start = pos + 1;
}
}
return this.db.get(start);
};
Chain.prototype.hasBlock = function hasBlock(hash) {
return !!this.byHash(hash);
};
Chain.prototype.hasOrphan = function hasOrphan(hash) {
return !!this.getOrphan(hash);
};
Chain.prototype.getBlock = function getBlock(hash) {
if (typeof hash === 'number')
return this.byHeight(hash);
return this.byHash(hash);
};
Chain.prototype.getOrphan = function getOrphan(hash) {
if (utils.isBuffer(hash))
hash = utils.toHex(hash);
else if (hash.hash)
hash = hash.hash('hex');
return this.orphan.bmap[hash] || null;
};
Chain.prototype.isFull = function isFull() {
var delta;
if (!this.tip)
return false;
delta = utils.now() - this.tip.ts;
return delta < 40 * 60;
};
Chain.prototype.fillPercent = function fillPercent() {
if (!this.tip)
return 0;
return Math.min(1, this.tip.ts / (utils.now() - 40 * 60));
};
Chain.prototype.hashRange = function hashRange(start, end) {
var hashes = [];
var i;
start = this.byTime(start);
end = this.byTime(end);
if (!start || !end)
return hashes;
for (i = start.height; i < end.height + 1; i++)
hashes.push(this.db.get(i).hash);
return hashes;
};
Chain.prototype.getLocator = function getLocator(start) {
var hashes = [];
var top = this.height();
var step = 1;
var i, existing;
if (start) {
if (utils.isBuffer(start))
start = utils.toHex(start);
else if (start.hash)
start = start.hash('hex');
}
if (typeof start === 'string') {
top = this.heightLookup[start];
if (top == null) {
// We could simply `return [start]` here,
// but there is no standardized "spacing"
// for locator hashes. Pretend this hash
// is our tip. This is useful for getheaders
// when not using headers-first.
hashes.push(start);
top = this.db.count() - 1;
}
} else if (typeof start === 'number') {
top = start;
}
assert(this.db.has(top));
i = top;
for (;;) {
existing = this.db.get(i);
assert(existing);
hashes.push(existing.hash);
i = i - step;
if (i <= 0) {
if (i + step !== 0)
hashes.push(network.genesis.hash);
break;
}
if (hashes.length >= 10)
step *= 2;
}
return hashes;
};
Chain.prototype.getOrphanRoot = function getOrphanRoot(hash) {
var self = this;
var root;
if (utils.isBuffer(hash))
hash = utils.toHex(hash);
else if (hash.hash)
hash = hash.hash('hex');
root = hash;
while (this.orphan.bmap[hash]) {
root = hash;
hash = this.orphan.bmap[hash].prevBlock;
}
return root;
};
Chain.prototype.getHeight = function getHeight(hash) {
var entry = this.byHash(hash);
if (!entry)
return -1;
return entry.height;
};
Chain.prototype.getNextBlock = function getNextBlock(hash) {
var entry = this.byHash(hash);
var next;
if (!entry)
return null;
next = entry.next;
if (!next)
return;
return next.hash;
};
Chain.prototype.getSize = function getSize() {
return this.db.count();
};
// Legacy
Chain.prototype.size = Chain.prototype.getSize;
Chain.prototype.height = function height() {
if (!this.tip)
return -1;
return this.tip.height;
};
Chain.prototype.getCurrentTarget = function getCurrentTarget() {
if (!this.tip)
return utils.toCompact(network.powLimit);
return this.getTarget(this.tip);
};
// Legacy
Chain.prototype.currentTarget = Chain.prototype.getCurrentTarget;
Chain.prototype.getTarget = function getTarget(last, block) {
var powLimit = utils.toCompact(network.powLimit);
var ts, first, i;
// Genesis
if (!last)
return powLimit;
// Do not retarget
if ((last.height + 1) % network.powDiffInterval !== 0) {
if (network.powAllowMinDifficultyBlocks) {
// Special behavior for testnet:
ts = block ? (block.ts || block) : utils.now();
if (ts > last.ts + network.powTargetSpacing * 2)
return powLimit;
while (last.prev
&& last.height % network.powDiffInterval !== 0
&& last.bits === powLimit) {
last = last.prev;
}
return last.bits;
}
return last.bits;
}
// Back 2 weeks
first = this.db.get(last.height - (network.powDiffInterval - 1));
assert(first);
return this.retarget(last, first);
};
// Legacy
Chain.prototype.target = Chain.prototype.getTarget;
Chain.prototype.retarget = function retarget(last, first) {
var powTargetTimespan = new bn(network.powTargetTimespan);
var actualTimespan, target;
if (network.powNoRetargeting)
return last.bits;
actualTimespan = new bn(last.ts - first.ts);
target = utils.fromCompact(last.bits);
if (actualTimespan.cmp(powTargetTimespan.divn(4)) < 0)
actualTimespan = powTargetTimespan.divn(4);
if (actualTimespan.cmp(powTargetTimespan.muln(4)) > 0)
actualTimespan = powTargetTimespan.muln(4);
target.imul(actualTimespan);
target = target.div(powTargetTimespan);
if (target.cmp(network.powLimit) > 0)
target = network.powLimit.clone();
return utils.toCompact(target);
};
Chain.prototype.toJSON = function toJSON() {
var entries = [];
var count = this.db.count();
var i;
for (i = 0; i < count; i++)
entries.push(this.db.get(i));
return {
v: 2,
type: 'chain',
network: network.type,
entries: entries.map(function(entry) {
return entry.toJSON();
})
};
};
Chain.prototype.fromJSON = function fromJSON(json) {
assert.equal(json.v, 2);
assert.equal(json.type, 'chain');
assert.equal(json.network, network.type);
json.entries.forEach(function(entry) {
this._saveEntry(bcoin.chainblock.fromJSON(this, entry));
}, this);
};
/**
* Expose
*/
module.exports = Chain;