feat(Node): use blockchain checkpoints by default

By default, supply a recent checkpoint when creating a Blockchain, in order to speed up the initial sync.

lib/constants.js

@@ -21,6 +21,30 @@ module.exports = {
       nonce: 414098458
     })
   },
+  checkpoints: {
+    livenet: {
+      height: 359000,
+      header: new bitcore.BlockHeader({
+        version: 3,
+        prevHash: u.toHash('000000000000000006ecee94daaa034bbd026cad52a9d3c6a5b7972716e5d566'),
+        merkleRoot: u.toHash('1e24b829d04e8e6fcb71fa0de364d6c0fa952c1cdb5fad446cf2a94dd203867a'),
+        time: 1433195458,
+        bits: 0x18171a8b,
+        nonce: 3020402664
+      })
+    },
+    testnet: {
+      height: 446000,
+      header: new bitcore.BlockHeader({
+        version: 3,
+        prevHash: u.toHash('00000000003d7bfe7baf59981a749017112b8018f0977356a3a21ea81a04d79d'),
+        merkleRoot: u.toHash('8a5829f9ac43b54819a02e44b2754458179de46c748f2d110bf97a0b02595267'),
+        time: 1432987428,
+        bits: 0x1a3fffc0,
+        nonce: 3771678460
+      })
+    }
+  },
   maxTarget: new BN('ffff0000000000000000000000000000000000000000000000000000', 'hex'),
   zeroHash: new Buffer('0000000000000000000000000000000000000000000000000000000000000000', 'hex'),
   timestampThreshold: 500000000,

lib/node.js

@@ -7,6 +7,7 @@ var PeerGroup = require('./peerGroup.js')
 var BlockStream = require('../lib/blockStream.js')
 var TransactionStream = require('../lib/transactionStream.js')
 var Wallet = require('../lib/wallet.js')
+var constants = require('../lib/constants.js')
 
 var Node = module.exports = function (opts, cb) {
   var self = this
@@ -30,7 +31,8 @@ var Node = module.exports = function (opts, cb) {
     peerGroup: this.peers,
     path: this.path + '/' + (opts.chainPath || this.network.name + '.chain'),
     store: opts.chainStore,
-    to: opts.to
+    to: opts.to,
+    checkpoint: constants.checkpoints[this.network.name]
   })
   this.chain.on('error', this._error.bind(this))