6 files changed, 72 insertions, 9 deletions
diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
index 980ecf10d..de3c060d6 100644
--- a/src/policy/fees.cpp
+++ b/src/policy/fees.cpp
@@ -87,7 +87,7 @@ double TxConfirmStats::EstimateMedianVal(int confTarget, double sufficientTxVal,
     int maxbucketindex = buckets.size() - 1;
 
     // requireGreater means we are looking for the lowest fee/priority such that all higher
-    // values pass, so we start at maxbucketindex (highest fee) and look at succesively
+    // values pass, so we start at maxbucketindex (highest fee) and look at successively
     // smaller buckets until we reach failure.  Otherwise, we are looking for the highest
     // fee/priority such that all lower values fail, and we go in the opposite direction.
     unsigned int startbucket = requireGreater ? maxbucketindex : 0;
diff --git a/src/policy/fees.h b/src/policy/fees.h
index 7a293267d..3fa31c39e 100644
--- a/src/policy/fees.h
+++ b/src/policy/fees.h
@@ -29,7 +29,7 @@ class CTxMemPool;
  * included in blocks before transactions of lower fee/priority.   So for
  * example if you wanted to know what fee you should put on a transaction to
  * be included in a block within the next 5 blocks, you would start by looking
- * at the bucket with with the highest fee transactions and verifying that a
+ * at the bucket with the highest fee transactions and verifying that a
  * sufficiently high percentage of them were confirmed within 5 blocks and
  * then you would look at the next highest fee bucket, and so on, stopping at
  * the last bucket to pass the test.   The average fee of transactions in this
@@ -87,13 +87,13 @@ private:
     // Count the total # of txs in each bucket
     // Track the historical moving average of this total over blocks
     std::vector<double> txCtAvg;
-    // and calcuate the total for the current block to update the moving average
+    // and calculate the total for the current block to update the moving average
     std::vector<int> curBlockTxCt;
 
     // Count the total # of txs confirmed within Y blocks in each bucket
     // Track the historical moving average of theses totals over blocks
     std::vector<std::vector<double> > confAvg; // confAvg[Y][X]
-    // and calcuate the totals for the current block to update the moving averages
+    // and calculate the totals for the current block to update the moving averages
     std::vector<std::vector<int> > curBlockConf; // curBlockConf[Y][X]
 
     // Sum the total priority/fee of all tx's in each bucket
diff --git a/src/policy/policy.cpp b/src/policy/policy.cpp
index 46c7f1894..019df7227 100644
--- a/src/policy/policy.cpp
+++ b/src/policy/policy.cpp
@@ -1,5 +1,5 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2014 The Bitcoin developers
+// Copyright (c) 2009-2015 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -23,9 +23,6 @@
      * 2. P2SH scripts with a crazy number of expensive
      *    CHECKSIG/CHECKMULTISIG operations
      *
-     * Check transaction inputs, and make sure any
-     * pay-to-script-hash transactions are evaluating IsStandard scripts
-     * 
      * Why bother? To avoid denial-of-service attacks; an attacker
      * can submit a standard HASH... OP_EQUAL transaction,
      * which will get accepted into blocks. The redemption
diff --git a/src/policy/policy.h b/src/policy/policy.h
index 31655f2f3..726864f19 100644
--- a/src/policy/policy.h
+++ b/src/policy/policy.h
@@ -1,5 +1,5 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2014 The Bitcoin developers
+// Copyright (c) 2009-2015 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
diff --git a/src/policy/rbf.cpp b/src/policy/rbf.cpp
new file mode 100644
index 000000000..98b1a1ba4
--- /dev/null
+++ b/src/policy/rbf.cpp
@@ -0,0 +1,46 @@
+// Copyright (c) 2016 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "policy/rbf.h"
+
+bool SignalsOptInRBF(const CTransaction &tx)
+{
+    BOOST_FOREACH(const CTxIn &txin, tx.vin) {
+        if (txin.nSequence < std::numeric_limits<unsigned int>::max()-1) {
+            return true;
+        }
+    }
+    return false;
+}
+
+bool IsRBFOptIn(const CTxMemPoolEntry &entry, CTxMemPool &pool)
+{
+    AssertLockHeld(pool.cs);
+
+    CTxMemPool::setEntries setAncestors;
+
+    // First check the transaction itself.
+    if (SignalsOptInRBF(entry.GetTx())) {
+        return true;
+    }
+
+    // If this transaction is not in our mempool, then we can't be sure
+    // we will know about all its inputs.
+    if (!pool.exists(entry.GetTx().GetHash())) {
+        throw std::runtime_error("Cannot determine RBF opt-in signal for non-mempool transaction\n");
+    }
+
+    // If all the inputs have nSequence >= maxint-1, it still might be
+    // signaled for RBF if any unconfirmed parents have signaled.
+    uint64_t noLimit = std::numeric_limits<uint64_t>::max();
+    std::string dummy;
+    pool.CalculateMemPoolAncestors(entry, setAncestors, noLimit, noLimit, noLimit, noLimit, dummy, false);
+
+    BOOST_FOREACH(CTxMemPool::txiter it, setAncestors) {
+        if (SignalsOptInRBF(it->GetTx())) {
+            return true;
+        }
+    }
+    return false;
+}
diff --git a/src/policy/rbf.h b/src/policy/rbf.h
new file mode 100644
index 000000000..925ce0d9b
--- /dev/null
+++ b/src/policy/rbf.h
@@ -0,0 +1,20 @@
+// Copyright (c) 2016 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_POLICY_RBF_H
+#define BITCOIN_POLICY_RBF_H
+
+#include "txmempool.h"
+
+// Check whether the sequence numbers on this transaction are signaling
+// opt-in to replace-by-fee, according to BIP 125
+bool SignalsOptInRBF(const CTransaction &tx);
+
+// Determine whether an in-mempool transaction is signaling opt-in to RBF
+// according to BIP 125
+// This involves checking sequence numbers of the transaction, as well
+// as the sequence numbers of all in-mempool ancestors.
+bool IsRBFOptIn(const CTxMemPoolEntry &entry, CTxMemPool &pool);
+
+#endif // BITCOIN_POLICY_RBF_H