face: Transport::getMtu
refs #3253
Change-Id: Ia4c5cfe210a99b798ce7d05f74ebdd7cfab214f4
diff --git a/daemon/face/udp-protocol.cpp b/daemon/face/udp-protocol.cpp
new file mode 100644
index 0000000..fb51a3a
--- /dev/null
+++ b/daemon/face/udp-protocol.cpp
@@ -0,0 +1,47 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2015, 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 "udp-protocol.hpp"
+
+namespace nfd {
+namespace udp {
+
+ssize_t
+computeMtu(const boost::asio::ip::udp::endpoint& localEndpoint)
+{
+ size_t mtu = 0;
+ if (localEndpoint.address().is_v4()) { // IPv4
+ mtu = std::numeric_limits<uint16_t>::max(); // maximum Total Length
+ mtu -= sizeof(uint32_t) * ((1 << 4) - 1); // maximum Internet Header Length
+ }
+ else { // IPv6
+ mtu = std::numeric_limits<uint16_t>::max(); // maximum Payload Length
+ }
+ mtu -= sizeof(uint16_t) * 4; // size of UDP header
+ return mtu;
+}
+
+} // namespace udp
+} // namespace nfd