improve coinbase height check.

lib/bcoin/block.js

@@ -14,7 +14,7 @@ var constants = bcoin.protocol.constants;
 
 function Block(data, subtype) {
   var self = this;
-  var tx;
+  var tx, height;
 
   if (!(this instanceof Block))
     return new Block(data, subtype);
@@ -61,8 +61,11 @@ function Block(data, subtype) {
 
     if (this.version >= 2) {
       tx = this.txs[0];
-      if (tx && tx.inputs[0] && +tx.inputs[0].out.hash === 0)
-        this._height = bcoin.script.coinbase(tx.inputs[0].script);
+      if (tx && tx.inputs[0] && +tx.inputs[0].out.hash === 0) {
+        var height = bcoin.script.coinbaseHeight(tx.inputs[0].script);
+        if (height > 0)
+          this._height = height;
+      }
     }
 
     this.invalid = !this._checkBlock();

lib/bcoin/script.js

@@ -1138,20 +1138,40 @@ script.isScripthashInput = function isScripthashInput(s, redeem) {
   return keys;
 };
 
-script.coinbase = function coinbase(s) {
-  var base = s._raw || script.encode(s);
-  var len = Math.min(base[0], base.length);
-  var height = 0;
-  var i, b;
+script.coinbaseHeight = function coinbaseHeight(s) {
+  var raw = s._raw || script.encode(s);
+  var height;
 
-  for (i = 0; i < len; i++) {
-    b = base[i + 1] & 0xff;
-    height |= b << (8 * i);
-  }
+  if (!Array.isArray(s[0]))
+    return -1;
+
+  if (raw[0] < 0x03 || s[0].length < 3)
+    return -1;
+
+  height = new bn(s[0].reverse()).toNumber();
+
+  // Last v1 block
+  if (height < 227835)
+    return -1;
 
   return height;
 };
 
+script.coinbase = function coinbase(s) {
+  var raw = s._raw || script.encode(s);
+  var data = script.coinbaseHeight(s);
+
+  if (height > 0)
+    raw = raw.slice(raw[0] + 1);
+
+  return {
+    height: height,
+    script: s,
+    data: raw,
+    text: utils.array2utf8(raw)
+  };
+};
+
 // https://github.com/bitcoin/bips/blob/master/bip-0066.mediawiki
 /**
  * A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len S> <S> <hashtype>