diff --git a/daemon/fw/algorithm.cpp b/daemon/fw/algorithm.cpp
new file mode 100644
index 0000000..7a1f2cc
--- /dev/null
+++ b/daemon/fw/algorithm.cpp
@@ -0,0 +1,147 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2016,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "algorithm.hpp"
+
+namespace nfd {
+namespace scope_prefix {
+const Name LOCALHOST("ndn:/localhost");
+const Name LOCALHOP("ndn:/localhop");
+} // namespace scope_prefix
+
+namespace fw {
+
+bool
+wouldViolateScope(const Face& inFace, const Interest& interest, const Face& outFace)
+{
+  if (outFace.getScope() == ndn::nfd::FACE_SCOPE_LOCAL) {
+    // forwarding to a local face is always allowed
+    return false;
+  }
+
+  if (scope_prefix::LOCALHOST.isPrefixOf(interest.getName())) {
+    // localhost Interests cannot be forwarded to a non-local face
+    return true;
+  }
+
+  if (scope_prefix::LOCALHOP.isPrefixOf(interest.getName())) {
+    // localhop Interests can be forwarded to a non-local face only if it comes from a local face
+    return inFace.getScope() != ndn::nfd::FACE_SCOPE_LOCAL;
+  }
+
+  // Interest name is not subject to scope control
+  return false;
+}
+
+bool
+violatesScope(const pit::Entry& pitEntry, const Face& outFace)
+{
+  if (outFace.getScope() == ndn::nfd::FACE_SCOPE_LOCAL) {
+    return false;
+  }
+  BOOST_ASSERT(outFace.getScope() == ndn::nfd::FACE_SCOPE_NON_LOCAL);
+
+  if (scope_prefix::LOCALHOST.isPrefixOf(pitEntry.getName())) {
+    // face is non-local, violates localhost scope
+    return true;
+  }
+
+  if (scope_prefix::LOCALHOP.isPrefixOf(pitEntry.getName())) {
+    // face is non-local, violates localhop scope unless PIT entry has local in-record
+    return std::none_of(pitEntry.in_begin(), pitEntry.in_end(),
+      [] (const pit::InRecord& inRecord) { return inRecord.getFace().getScope() == ndn::nfd::FACE_SCOPE_LOCAL; });
+  }
+
+  // Name is not subject to scope control
+  return false;
+}
+
+bool
+canForwardToLegacy(const pit::Entry& pitEntry, const Face& face)
+{
+  time::steady_clock::TimePoint now = time::steady_clock::now();
+
+  bool hasUnexpiredOutRecord = std::any_of(pitEntry.out_begin(), pitEntry.out_end(),
+    [&face, &now] (const pit::OutRecord& outRecord) {
+      return &outRecord.getFace() == &face && outRecord.getExpiry() >= now;
+    });
+  if (hasUnexpiredOutRecord) {
+    return false;
+  }
+
+  bool hasUnexpiredOtherInRecord = std::any_of(pitEntry.in_begin(), pitEntry.in_end(),
+    [&face, &now] (const pit::InRecord& inRecord) {
+      return &inRecord.getFace() != &face && inRecord.getExpiry() >= now;
+    });
+  if (!hasUnexpiredOtherInRecord) {
+    return false;
+  }
+
+  return !violatesScope(pitEntry, face);
+}
+
+int
+findDuplicateNonce(const pit::Entry& pitEntry, uint32_t nonce, const Face& face)
+{
+  int dnw = DUPLICATE_NONCE_NONE;
+
+  for (const pit::InRecord& inRecord : pitEntry.getInRecords()) {
+    if (inRecord.getLastNonce() == nonce) {
+      if (&inRecord.getFace() == &face) {
+        dnw |= DUPLICATE_NONCE_IN_SAME;
+      }
+      else {
+        dnw |= DUPLICATE_NONCE_IN_OTHER;
+      }
+    }
+  }
+
+  for (const pit::OutRecord& outRecord : pitEntry.getOutRecords()) {
+    if (outRecord.getLastNonce() == nonce) {
+      if (&outRecord.getFace() == &face) {
+        dnw |= DUPLICATE_NONCE_OUT_SAME;
+      }
+      else {
+        dnw |= DUPLICATE_NONCE_OUT_OTHER;
+      }
+    }
+  }
+
+  return dnw;
+}
+
+bool
+hasPendingOutRecords(const pit::Entry& pitEntry)
+{
+  time::steady_clock::TimePoint now = time::steady_clock::now();
+  return std::any_of(pitEntry.out_begin(), pitEntry.out_end(),
+                      [&now] (const pit::OutRecord& outRecord) {
+                        return outRecord.getExpiry() >= now &&
+                               outRecord.getIncomingNack() == nullptr;
+                      });
+}
+
+} // namespace fw
+} // namespace nfd