From adbb0099a1f40e17405a509e2598a50e152a9a24 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Tue, 8 Dec 2015 11:24:22 -0800
Subject: [PATCH] add checklocktimeverify. pass in tx and input to execute()
 instead of using hasher callback.

---
 lib/bcoin/protocol/constants.js |  5 +++-
 lib/bcoin/script.js             | 49 +++++++++++++++++++++++++++------
 lib/bcoin/tx.js                 |  7 ++---
 3 files changed, 46 insertions(+), 15 deletions(-)

diff --git a/lib/bcoin/protocol/constants.js b/lib/bcoin/protocol/constants.js
index f52804e7..e22dcb83 100644
--- a/lib/bcoin/protocol/constants.js
+++ b/lib/bcoin/protocol/constants.js
@@ -137,7 +137,8 @@ exports.opcodes = {
   checksig: 0xac,
   checksigverify: 0xad,
   checkmultisig: 0xae,
-  checkmultisigverify: 0xaf
+  checkmultisigverify: 0xaf,
+  checklocktimeverify: 0xb1
 };
 
 for (var i = 1; i <= 16; i++)
@@ -169,3 +170,5 @@ exports.block = {
   maxSigops: 1000000 / 50,
   maxOrphanTx: 1000000 / 100
 };
+
+exports.locktimeThreshold = 500000000; // Tue Nov  5 00:53:20 1985 UTC
diff --git a/lib/bcoin/script.js b/lib/bcoin/script.js
index 615d1e96..0adc2478 100644
--- a/lib/bcoin/script.js
+++ b/lib/bcoin/script.js
@@ -130,10 +130,12 @@ script.verify = function verify(hash, sig, pub) {
   }
 };
 
-script.execute = function execute(s, stack, hasher) {
+script.execute = function execute(s, stack, tx, index) {
   if (s.length > 10000)
     return false;
 
+  var input = tx.inputs[index];
+
   for (var pc = 0; pc < s.length; pc++) {
     var o = s[pc];
     if (Array.isArray(o)) {
@@ -145,6 +147,8 @@ script.execute = function execute(s, stack, hasher) {
         return false;
 
       stack.push(stack[stack.length - 1]);
+    } else if (o === 'drop') {
+      stack.pop();
     } else if (o === 'hash160') {
       if (stack.length === 0)
         return false;
@@ -163,7 +167,7 @@ script.execute = function execute(s, stack, hasher) {
       }
 
     } else if (o === 'checksigverify' || o === 'checksig') {
-      if (!hasher || stack.length < 2)
+      if (!tx || stack.length < 2)
         return false;
 
       var pub = stack.pop();
@@ -172,9 +176,8 @@ script.execute = function execute(s, stack, hasher) {
       if (!constants.rhashType[type & 0x7f])
         return false;
 
-      var hash = hasher;
-      if (typeof hash === 'function')
-        hash = hash(type);
+      var subscript = input.out.tx.getSubscript(input.out.index);
+      var hash = tx.subscriptHash(index, subscript, type);
 
       var res = script.verify(hash, sig.slice(0, -1), pub);
       if (o === 'checksigverify') {
@@ -184,7 +187,7 @@ script.execute = function execute(s, stack, hasher) {
         stack.push(res ? [ 1 ] : []);
       }
     } else if (o === 'checkmultisigverify' || o === 'checkmultisig') {
-      if (!hasher || stack.length < 3)
+      if (!tx || stack.length < 3)
         return false;
 
       var n = stack.pop();
@@ -220,9 +223,8 @@ script.execute = function execute(s, stack, hasher) {
         if (!constants.rhashType[type & 0x7f])
           return false;
 
-        var hash = hasher;
-        if (typeof hash === 'function')
-          hash = hash(type);
+        var subscript = input.out.tx.getSubscript(input.out.index);
+        var hash = tx.subscriptHash(index, subscript, type);
 
         var res = false;
         for (; !res && j < n; j++)
@@ -241,6 +243,35 @@ script.execute = function execute(s, stack, hasher) {
       } else {
         stack.push(res ? [ 1 ] : []);
       }
+    } else if (o === 'checklocktimeverify') {
+      // input: [[], sig1, sig2, 1]
+      // prev_out: [[lock], 'checklocktimeverify', 'drop',
+      //            'dup', 'hash160', pubkey, 'equalverify', 'checksig']
+      if (stack.length === 0)
+        return false;
+
+      var lock = stack[stack.length - 1];
+      if (lock.length !== 1)
+        return false;
+
+      lock = lock[0];
+
+      if (lock < 0)
+        return false;
+
+      var threshold = constants.locktimeThreshold;
+      if (!(
+        (tx.lock <  threshold && lock <  threshold) ||
+        (tx.lock >= threshold && lock >= threshold)
+      )) {
+        return false;
+      }
+
+      if (lock > tx.lock)
+        return false;
+
+      if (input.seq === 0xffffffff)
+        return false;
     } else {
       // Unknown operation
       return false;
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index d677b5c2..5b7fbc5c 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -427,13 +427,10 @@ TX.prototype.verify = function verify(index, force) {
 
     assert(input.out.tx.outputs.length > input.out.index);
 
-    var subscript = input.out.tx.getSubscript(input.out.index);
-    var hasher = this.subscriptHash.bind(this, i, subscript);
-
     var stack = [];
-    bcoin.script.execute(input.script, stack);
+    bcoin.script.execute(input.script, stack, this, i);
     var prev = input.out.tx.outputs[input.out.index].script;
-    var res = bcoin.script.execute(prev, stack, hasher);
+    var res = bcoin.script.execute(prev, stack, this, i);
     if (!res)
       return false;