From cd3f04268af8b814a58e1b484c3f202b800912ac Mon Sep 17 00:00:00 2001
From: Fedor Indutny <fedor@indutny.com>
Date: Sat, 3 May 2014 16:51:16 +0400
Subject: [PATCH] block: verify

---
 lib/bcoin/block.js |  3 +--
 lib/bcoin/chain.js |  4 ++--
 lib/bcoin/utils.js | 43 +++++++++++++++++++++++++++++++++++++++++++
 test/utils-test.js | 10 ++++++++++
 4 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/lib/bcoin/block.js b/lib/bcoin/block.js
index af56cb6b..08c08091 100644
--- a/lib/bcoin/block.js
+++ b/lib/bcoin/block.js
@@ -37,8 +37,7 @@ Block.prototype.abbr = function abbr() {
 };
 
 Block.prototype.verify = function verify() {
-  // TODO(indutny): verify nonce
-  return true;
+  return utils.testTarget(this.bits, this.hash());
 };
 
 Block.prototype.render = function render(framer) {
diff --git a/lib/bcoin/chain.js b/lib/bcoin/chain.js
index 70e02b52..30a8db70 100644
--- a/lib/bcoin/chain.js
+++ b/lib/bcoin/chain.js
@@ -168,11 +168,11 @@ Chain.prototype.get = function get(hash, cb) {
 
   if (this.request.map[hash]) {
     this.request.map[hash].push(cb);
-    this.request.count++;
   } else {
     this.request.map[hash] = [ cb ];
+    this.request.count++;
+    this.emit('missing', hash);
   }
-  this.emit('missing', hash);
 };
 
 Chain.prototype.isFull = function isFull() {
diff --git a/lib/bcoin/utils.js b/lib/bcoin/utils.js
index 3282e52c..148a82cd 100644
--- a/lib/bcoin/utils.js
+++ b/lib/bcoin/utils.js
@@ -223,3 +223,46 @@ function binaryInsert(list, item, compare, search) {
   return start;
 }
 utils.binaryInsert = binaryInsert;
+
+function bitsToTarget(bits) {
+  var len = (bits >>> 24) & 0xff;
+  var hi = (bits >>> 16) & 0xff;
+  var mid = (bits >>> 8) & 0xff;
+  var lo = bits & 0xff;
+
+  var res = new Array(len);
+  for (var i = 0; i < len - 3; i++)
+    res[i] = 0;
+  res[i++] = lo;
+  res[i++] = mid;
+  res[i++] = hi;
+
+  if (hi === 0)
+    res.pop();
+  if (hi === 0 && mid === 0)
+    res.pop();
+
+  return res;
+}
+utils.bitsToTarget = bitsToTarget;
+
+function testTarget(target, hash) {
+  if (typeof target === 'number')
+    target = bitsToTarget(target);
+  hash = utils.toArray(hash, 'hex');
+
+  for (var i = hash.length - 1; i >= target.length; i--)
+    if (hash[i] !== 0)
+      return false;
+
+  for (; i >= 0; i--) {
+    if (hash[i] === target[i])
+      continue;
+    if (hash[i] > target[i])
+      return false;
+    break;
+  }
+
+  return true;
+}
+utils.testTarget = testTarget;
diff --git a/test/utils-test.js b/test/utils-test.js
index 7f6a869a..d0371998 100644
--- a/test/utils-test.js
+++ b/test/utils-test.js
@@ -8,4 +8,14 @@ describe('Utils', function() {
     assert.equal(b, '1116h8cQN');
     assert.deepEqual(bcoin.utils.fromBase58(b), arr);
   });
+
+  it('should translate bits to target', function() {
+    var bits = 0x1900896c;
+    var hash = bcoin.utils.toArray(
+      '672b3f1bb11a994267ea4171069ba0aa4448a840f38e8f340000000000000000',
+      'hex'
+    );
+    var target = bcoin.utils.bitsToTarget(bits);
+    assert(bcoin.utils.testTarget(target, hash));
+  });
 });