mempool: do not accept replace by fee.

lib/mempool/mempool.js

@@ -644,6 +644,12 @@ Mempool.prototype._addTX = co(function* _addTX(tx) {
         ret.reason,
         ret.score);
     }
+    if (tx.isRBF()) {
+      throw new VerifyError(tx,
+        'nonstandard',
+        'replace-by-fee',
+        0);
+    }
   }
 
   result = yield this.chain.checkFinal(this.chain.tip, tx, lockFlags);

lib/primitives/input.js

@@ -221,6 +221,15 @@ Input.prototype.isFinal = function isFinal() {
   return this.sequence === 0xffffffff;
 };
 
+/**
+ * Test to see if nSequence is less than 0xfffffffe.
+ * @returns {Boolean}
+ */
+
+Input.prototype.isRBF = function isRBF() {
+  return this.sequence < 0xfffffffe;
+};
+
 /**
  * Test to see if outpoint is null.
  * @returns {Boolean}

lib/primitives/tx.js

@@ -782,6 +782,31 @@ TX.prototype.isCoinbase = function isCoinbase() {
   return this.inputs.length === 1 && this.inputs[0].prevout.isNull();
 };
 
+/**
+ * Test whether the transaction is a replacement.
+ * @returns {Boolean}
+ */
+
+TX.prototype.isRBF = function isRBF() {
+  var i, input;
+
+  for (i = 0; i < this.inputs.length; i++) {
+    input = this.inputs[i];
+
+    if (!input.isRBF())
+      continue;
+
+    if (this.version === 2) {
+      if (!(input.sequence & constants.sequence.DISABLE_FLAG))
+        continue;
+    }
+
+    return true;
+  }
+
+  return false;
+};
+
 /**
  * Calculate the fee for the transaction.
  * @returns {Amount} fee (zero if not all coins are available).