From d49b04158f9d69764eee32359671cb13c021761b Mon Sep 17 00:00:00 2001
From: Fedor Indutny <fedor@indutny.com>
Date: Sat, 10 May 2014 19:45:03 +0400
Subject: [PATCH] block: validate partial merkle tree

---
 lib/bcoin/block.js | 60 +++++++++++++++++++++++++++++++++++++++++++---
 lib/bcoin/tx.js    |  2 +-
 test/block-test.js | 39 ++++++++++++++++++++++++++++++
 3 files changed, 97 insertions(+), 4 deletions(-)
 create mode 100644 test/block-test.js

diff --git a/lib/bcoin/block.js b/lib/bcoin/block.js
index 8dda0653..d562ef34 100644
--- a/lib/bcoin/block.js
+++ b/lib/bcoin/block.js
@@ -18,7 +18,14 @@ function Block(data) {
   });
   this.flags = data.flags;
 
+  // List of matched TXs
+  this.tx = [];
+  this.invalid = false;
+
   this._hash = null;
+
+  // Verify partial merkle tree and fill `ts` array
+  this._verifyMerkle();
 }
 module.exports = Block;
 
@@ -42,13 +49,60 @@ Block.prototype.abbr = function abbr() {
 };
 
 Block.prototype.verify = function verify() {
-  return utils.testTarget(this.bits, this.hash());
+  return !this.invalid && utils.testTarget(this.bits, this.hash());
 };
 
 Block.prototype.render = function render(framer) {
   return [];
 };
 
-Block.prototype.hasMerkle = function hasMerkle(hash) {
-  return this.hashes.indexOf(hash) !== -1;
+Block.prototype.hasTX = function hasTX(hash) {
+  return this.tx.indexOf(hash) !== -1;
+};
+
+Block.prototype._verifyMerkle = function verifyMerkle() {
+  var height = 0;
+
+  // Count leafs
+  for (var i = this.totalTX; i > 0; i >>= 1)
+    height++;
+  if (this.totalTX > (1 << (height - 1)))
+    height++;
+
+  var tx = [];
+  var i = 0;
+  var j = 0;
+  var hashes = this.hashes;
+  var flags = this.flags;
+
+  var root = visit(1);
+  if (!root || root !== this.merkleRoot) {
+    this.invalid = true;
+    return;
+  }
+  this.tx = tx;
+  function visit(depth) {
+    if (i === flags.length * 8 || j === hashes.length)
+      return null;
+
+    var flag = (flags[i >> 3] >>> (i & 7)) & 1;
+    i++;
+
+    if (flag === 0 || depth === height) {
+      if (depth === height)
+        tx.push(hashes[j]);
+      return hashes[j++];
+    }
+
+    // Go deeper
+    var left = visit(depth + 1);
+    if (!left)
+      return null;
+    var right = visit(depth + 1);
+    if (right === left)
+      return null;
+    if (!right)
+      right = left;
+    return utils.toHex(utils.dsha256(left + right, 'hex'));
+  }
 };
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index cfb51c13..51129c2b 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -33,7 +33,7 @@ function TX(data, block) {
     }, this);
   }
 
-  if (!data.ts && block && block.hasMerkle(this.hash('hex')))
+  if (!data.ts && block && block.hasTX(this.hash('hex')))
     this.ts = block.ts;
 }
 module.exports = TX;
diff --git a/test/block-test.js b/test/block-test.js
new file mode 100644
index 00000000..fb55b5ff
--- /dev/null
+++ b/test/block-test.js
@@ -0,0 +1,39 @@
+var assert = require('assert');
+var bn = require('bn.js');
+var bcoin = require('../');
+
+describe('Block', function() {
+  it('should parse partial merkle tree', function() {
+    var block = bcoin.block({
+      type: 'block',
+      version: 2,
+      prevBlock: 'd1831d4411bdfda89d9d8c842b541beafd1437fc560dbe5c0000000000000000',
+      merkleRoot: '28bec1d35af480ba3884553d72694f6ba6c163a5c081d7e6edaec15f373f19af',
+      ts: 1399713634,
+      bits: 419465580,
+      nonce: 1186968784,
+      totalTX: 461,
+      hashes:[
+        '7d22e53bce1bbb3294d1a396c5acc45bdcc8f192cb492f0d9f55421fd4c62de1',
+        '9d6d585fdaf3737b9a54aaee1dd003f498328d699b7dfb42dd2b44b6ebde2333',
+        '8b61da3053d6f382f2145bdd856bc5dcf052c3a11c1784d3d51b2cbe0f6d0923',
+        'd7bbaae4716cb0d329d755b707cee588cddc68601f99bc05fef1fabeb8dfe4a0',
+        '7393f84cd04ca8931975c66282ebf1847c78d8de6c2578d4f9bae23bc6f30857',
+        'ec8c51de3170301430ec56f6703533d9ea5b05c6fa7068954bcb90eed8c2ee5c',
+        'c7c152869db09a5ae2291fa03142912d9d7aba75be7d491a8ac4230ee9a920cb',
+        '5adbf04583354515a225f2c418de7c5cdac4cef211820c79717cd2c50412153f',
+        '1f5e46b9da3a8b1241f4a1501741d3453bafddf6135b600b926e3f4056c6d564',
+        '33825657ba32afe269819f01993bd77baba86379043168c94845d32370e53562' ],
+      flags: [ 245, 90, 0 ]
+    });
+
+    assert(block.verify());
+    assert.equal(block.tx.length, 2);
+    assert.equal(
+      block.tx[0],
+      '7393f84cd04ca8931975c66282ebf1847c78d8de6c2578d4f9bae23bc6f30857');
+    assert.equal(
+      block.tx[1],
+      'ec8c51de3170301430ec56f6703533d9ea5b05c6fa7068954bcb90eed8c2ee5c');
+  });
+});