tx: add bip69 sorting.

lib/bcoin/tx.js

@@ -1166,6 +1166,40 @@ TX.prototype.fill = function fill(unspent, address, fee) {
   return result;
 };
 
+// https://github.com/bitcoin/bips/blob/master/bip-0069.mediawiki
+TX.prototype.sortMembers = function sortMembers() {
+  var changeOutput;
+
+  if (this.changeIndex !== -1) {
+    changeOutput = this.outputs[this.changeIndex];
+    assert(changeOutput);
+  }
+
+  this.inputs = this.inputs.slice().sort(function(a, b) {
+    var res = new bn(a.prevout.hash, 'hex').cmp(new bn(b.prevout.hash, 'hex'));
+    if (res !== 0)
+      return res;
+
+    return a.prevout.index - b.prevout.index;
+  });
+
+  this.outputs = this.outputs.slice().sort(function(a, b) {
+    var res = a.value.cmp(b.value);
+    if (res !== 0)
+      return res;
+
+    a = bcoin.script.encode(a.script);
+    b = bcoin.script.encode(b.script);
+
+    return new bn(a).cmp(b);
+  });
+
+  if (this.changeIndex !== -1) {
+    this.changeIndex = this.outputs.indexOf(changeOutput);
+    assert(this.changeIndex !== -1);
+  }
+};
+
 // Legacy
 TX.prototype.fillUnspent = TX.prototype.fill;
 TX.prototype.fillInputs = TX.prototype.fill;
@@ -1258,7 +1292,7 @@ TX.prototype.getFunds = function getFunds(side) {
 // Legacy
 TX.prototype.funds = TX.prototype.getFunds;
 
-TX.prototype.getTargetTime = function getTargetTime() {
+TX.prototype.getTargetLocktime = function getTargetLocktime() {
   var bestValue = 0;
   var i, locktime, bestType;
 

lib/bcoin/wallet.js

@@ -392,27 +392,35 @@ Wallet.prototype.createTX = function createTX(outputs, fee) {
   if (!Array.isArray(outputs))
     outputs = [outputs];
 
+  // Add the outputs
   outputs.forEach(function(output) {
     tx.addOutput(output);
   });
 
+  // Fill the inputs with unspents
   if (!this.fill(tx, null, fee))
     return;
 
+  // Sort members a la BIP69
+  tx.sortMembers();
+
   // Find the necessary locktime if there is
   // a checklocktimeverify script in the unspents.
-  target = tx.getTargetTime();
+  target = tx.getTargetLocktime();
 
   // No target value. The unspents have an
   // incompatible locktime type.
   if (!target)
     return;
 
+  // Set the locktime to target value or
+  // `height - whatever` to avoid fee snipping.
   if (target.value > 0)
     tx.setLocktime(target.value);
   else
     tx.avoidFeeSnipping();
 
+  // Sign the inputs
   this.sign(tx);
 
   return tx;