management: Making LocalControlHeader encoding independent of Interest/Data wire

Boost.Asio support multi-buffer send operation, which is enabled in this
commit for prepending (potentially different) LocalControlHeader's to
Interest/Data wire.

Change-Id: I39b979f89f196d3e47d6466fb71f6d440bce74d4
refs: #1265
diff --git a/src/transport/stream-transport.hpp b/src/transport/stream-transport.hpp
new file mode 100644
index 0000000..f98b988
--- /dev/null
+++ b/src/transport/stream-transport.hpp
@@ -0,0 +1,337 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
+/**
+ * Copyright (C) 2013-2014 Regents of the University of California.
+ * See COPYING for copyright and distribution information.
+ */
+
+#ifndef NDN_TRANSPORT_STREAM_TRANSPORT_HPP
+#define NDN_TRANSPORT_STREAM_TRANSPORT_HPP
+
+#include "../common.hpp"
+
+namespace ndn {
+
+const size_t MAX_LENGTH = 9000;
+
+template<class BaseTransport, class Protocol>
+class StreamTransportImpl
+{
+public:
+  typedef BaseTransport base_transport;
+  typedef Protocol      protocol;
+  typedef StreamTransportImpl<BaseTransport,Protocol> impl;
+
+  StreamTransportImpl(base_transport& transport, boost::asio::io_service& ioService)
+    : m_transport(transport)
+    , m_socket(ioService)
+    , m_partialDataSize(0)
+    , m_connectionInProgress(false)
+    , m_connectTimer(ioService)
+  {
+  }
+  
+  void
+  connectHandler(const boost::system::error_code& error)
+  {
+    m_connectionInProgress = false;
+    m_connectTimer.cancel();
+
+    if (!error)
+      {
+        m_partialDataSize = 0;
+        m_socket.async_receive(boost::asio::buffer(m_inputBuffer, MAX_LENGTH), 0,
+                               bind(&impl::handle_async_receive, this, _1, _2));
+
+        m_transport.m_isConnected = true;
+
+        for (std::list<Block>::iterator i = m_sendQueue.begin(); i != m_sendQueue.end(); ++i)
+          m_socket.async_send(boost::asio::buffer(i->wire(), i->size()),
+                              bind(&impl::handle_async_send, this, _1, *i));
+
+        for (std::list< std::pair<Block,Block> >::iterator i = m_sendPairQueue.begin();
+             i != m_sendPairQueue.end(); ++i)
+          {
+            std::vector<boost::asio::const_buffer> buffer;
+            buffer.reserve(2);
+            buffer.push_back(boost::asio::buffer(i->first.wire(),  i->first.size()));
+            buffer.push_back(boost::asio::buffer(i->second.wire(), i->second.size()));
+            m_socket.async_send(buffer,
+                                bind(&impl::handle_async_send, this, _1, i->first, i->second));
+          }
+        
+        m_sendQueue.clear();
+        m_sendPairQueue.clear();
+      }
+    else
+      {
+        // may need to throw exception
+        m_transport.m_isConnected = false;
+        m_transport.close();
+        throw Transport::Error(error, "error while connecting to the forwarder");
+      }
+  }
+
+  void
+  connectTimeoutHandler(const boost::system::error_code& error)
+  {
+    if (error) // e.g., cancelled timer
+      return;
+
+    m_connectionInProgress = false;
+    m_transport.m_isConnected = false;
+    m_socket.close();
+    throw Transport::Error(error, "error while connecting to the forwarder");
+  }
+
+  void
+  connect(const typename protocol::endpoint& endpoint)
+  {
+    if (!m_connectionInProgress) {
+      m_connectionInProgress = true;
+
+      // Wait at most 4 seconds to connect
+      /// @todo Decide whether this number should be configurable
+      m_connectTimer.expires_from_now(boost::posix_time::seconds(4));
+      m_connectTimer.async_wait(bind(&impl::connectTimeoutHandler, this, _1));
+
+      m_socket.open();
+      m_socket.async_connect(endpoint,
+                             bind(&impl::connectHandler, this, _1));
+    }
+  }
+  
+  void 
+  close()
+  {
+    m_connectTimer.cancel();
+    m_socket.close();
+    m_transport.m_isConnected = false;
+    m_sendQueue.clear();
+    m_sendPairQueue.clear();
+  }
+
+  void
+  send(const Block& wire)
+  {
+    if (!m_transport.m_isConnected)
+      m_sendQueue.push_back(wire);
+    else
+      m_socket.async_send(boost::asio::buffer(wire.wire(), wire.size()),
+                         bind(&impl::handle_async_send, this, _1, wire));
+  }
+
+  void
+  send(const Block& header, const Block& payload)
+  {
+    if (!m_transport.m_isConnected)
+      {
+        m_sendPairQueue.push_back(std::make_pair(header, payload));
+      }
+    else
+      {
+        std::vector<boost::asio::const_buffer> buffers;
+        buffers.reserve(2);
+        buffers.push_back(boost::asio::buffer(header.wire(),  header.size()));
+        buffers.push_back(boost::asio::buffer(payload.wire(), payload.size()));
+                          
+        m_socket.async_send(buffers,
+                            bind(&impl::handle_async_send, this, _1, header, payload));
+      }
+  }
+  
+  inline void
+  processAll(uint8_t* buffer, size_t& offset, size_t availableSize)
+  {
+    while(offset < availableSize)
+      {
+        Block element(buffer + offset, availableSize - offset);
+        m_transport.receive(element);
+
+        offset += element.size();
+      }
+  }
+  
+  void
+  handle_async_receive(const boost::system::error_code& error, std::size_t bytes_recvd)
+  {
+    /// @todo The socket is not datagram, so need to have internal buffer to handle partial data reception
+
+    if (error)
+      {
+        if (error == boost::system::errc::operation_canceled) {
+          // async receive has been explicitly cancelled (e.g., socket close)
+          return;
+        }
+        
+        m_socket.close(); // closing at this point may not be that necessary
+        m_transport.m_isConnected = true;
+        throw Transport::Error(error, "error while receiving data from socket");
+      }
+    
+    if (!error && bytes_recvd > 0)
+      {
+        // m_inputBuffer has bytes_recvd received bytes of data
+        if (m_partialDataSize > 0)
+          {
+            size_t newDataSize = std::min(bytes_recvd, MAX_LENGTH-m_partialDataSize);
+            std::copy(m_inputBuffer, m_inputBuffer + newDataSize, m_partialData + m_partialDataSize);
+
+            m_partialDataSize += newDataSize;
+              
+            size_t offset = 0;
+            try
+              {
+                processAll(m_partialData, offset, m_partialDataSize);
+
+                // no exceptions => processed the whole thing
+                if (bytes_recvd - newDataSize > 0)
+                  {
+                    // there is a little bit more data available
+                        
+                    offset = 0;
+                    m_partialDataSize = bytes_recvd - newDataSize;
+                    std::copy(m_inputBuffer + newDataSize, m_inputBuffer + newDataSize + m_partialDataSize, m_partialData);
+
+                    processAll(m_partialData, offset, m_partialDataSize);
+
+                    // no exceptions => processed the whole thing
+                    m_partialDataSize = 0;
+                  }
+                else
+                  {
+                    // done processing
+                    m_partialDataSize = 0;
+                  }
+              }
+            catch(Tlv::Error &)
+              {
+                if (offset > 0)
+                  {
+                    m_partialDataSize -= offset;
+                    std::copy(m_partialData + offset, m_partialData + offset + m_partialDataSize, m_partialData);
+                  }
+                else if (offset == 0 && m_partialDataSize == MAX_LENGTH)
+                  {
+                    // very bad... should close connection
+                    m_socket.close();
+                    m_transport.m_isConnected = true;
+                    throw Transport::Error(boost::system::error_code(),
+                                           "input buffer full, but a valid TLV cannot be decoded");
+                  }
+              }
+          }
+        else
+          {
+            size_t offset = 0;
+            try
+              {
+                processAll(m_inputBuffer, offset, bytes_recvd);
+              }
+            catch(Tlv::Error &error)
+              {
+                if (offset > 0)
+                  {
+                    m_partialDataSize = bytes_recvd - offset;
+                    std::copy(m_inputBuffer + offset, m_inputBuffer + offset + m_partialDataSize, m_partialData);
+                  }
+              }
+          }
+      }
+
+    m_socket.async_receive(boost::asio::buffer(m_inputBuffer, MAX_LENGTH), 0,
+                          bind(&impl::handle_async_receive, this, _1, _2));
+  }
+
+  void
+  handle_async_send(const boost::system::error_code& error, const Block& wire)
+  {
+    // pass (needed to keep data block alive during the send)
+  }
+
+  void
+  handle_async_send(const boost::system::error_code& error,
+                    const Block& header, const Block& payload)
+  {
+    // pass (needed to keep data blocks alive during the send)
+  }
+
+protected:
+  base_transport& m_transport;
+  
+  typename protocol::socket m_socket;
+  uint8_t m_inputBuffer[MAX_LENGTH];
+
+  uint8_t m_partialData[MAX_LENGTH];
+  size_t m_partialDataSize;
+
+  std::list< Block > m_sendQueue;
+  std::list< std::pair<Block, Block> > m_sendPairQueue;
+  bool m_connectionInProgress;
+
+  boost::asio::deadline_timer m_connectTimer;
+};
+
+
+template<class BaseTransport, class Protocol>
+class StreamTransportWithResolverImpl : public StreamTransportImpl<BaseTransport, Protocol>
+{
+public:
+  typedef BaseTransport base_transport;
+  typedef Protocol      protocol;
+  typedef StreamTransportWithResolverImpl<BaseTransport,Protocol> impl;
+
+  StreamTransportWithResolverImpl(base_transport& transport, boost::asio::io_service& ioService)
+    : StreamTransportImpl<base_transport, protocol>(transport, ioService)
+  {
+  }
+  
+  void
+  resolveHandler(const boost::system::error_code& error,
+                 typename protocol::resolver::iterator endpoint,
+                 const shared_ptr<typename protocol::resolver>&)
+  {
+    if (error)
+      {
+        if (error == boost::system::errc::operation_canceled)
+          return;
+        
+        throw Transport::Error(error, "Error during resolution of host or port");
+      }
+    
+    typename protocol::resolver::iterator end;
+    if (endpoint == end)
+      {
+        this->m_connectionInProgress = false;
+        this->m_transport.m_isConnected = false;
+        this->m_socket.close();
+        throw Transport::Error(error, "Unable to resolve because host or port");
+      }
+
+    this->m_socket.async_connect(*endpoint,
+                                 bind(&impl::connectHandler, this, _1));
+  }
+  
+  void
+  connect(const typename protocol::resolver::query& query)
+  {
+    if (!this->m_connectionInProgress) {
+      this->m_connectionInProgress = true;
+
+      // Wait at most 4 seconds to connect
+      /// @todo Decide whether this number should be configurable
+      this->m_connectTimer.expires_from_now(boost::posix_time::seconds(4));
+      this->m_connectTimer.async_wait(bind(&impl::connectTimeoutHandler, this, _1));
+
+      // typename boost::asio::ip::basic_resolver< protocol > resolver;
+      shared_ptr<typename protocol::resolver> resolver =
+        make_shared<typename protocol::resolver>(boost::ref(this->m_socket.get_io_service()));
+
+      resolver->async_resolve(query, bind(&impl::resolveHandler, this, _1, _2, resolver));
+    }
+  }
+};
+
+
+} // namespace ndn
+
+#endif // NDN_TRANSPORT_STREAM_TRANSPORT_HPP
diff --git a/src/transport/tcp-transport.cpp b/src/transport/tcp-transport.cpp
index 3c773a8..24ec85c 100644
--- a/src/transport/tcp-transport.cpp
+++ b/src/transport/tcp-transport.cpp
@@ -1,271 +1,19 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
 /**
- * Copyright (C) 2013 Regents of the University of California.
- * @author: Jeff Thompson <jefft0@remap.ucla.edu>
+ * Copyright (C) 2013-2014 Regents of the University of California.
  * See COPYING for copyright and distribution information.
  */
 
 #include "common.hpp"
 
 #include "tcp-transport.hpp"
-
-#if NDN_CPP_HAVE_CXX11
-// In the std library, the placeholders are in a different namespace than boost.
-using namespace ndn::func_lib::placeholders;
-#endif
-
-using namespace std;
-typedef boost::asio::ip::tcp protocol;
+#include "stream-transport.hpp"
 
 namespace ndn {
 
-const size_t MAX_LENGTH = 9000;
-
-class TcpTransport::Impl
-{
-public:
-  Impl(TcpTransport &transport)
-    : transport_(transport)
-    , socket_(*transport_.ioService_)
-    , partialDataSize_(0)
-    , connectionInProgress_(false)
-    , connectTimer_(*transport_.ioService_)
-  {
-  }
-
-  void
-  connectHandler(const boost::system::error_code& error)
-  {
-    connectionInProgress_ = false;
-    connectTimer_.cancel();
-
-    if (!error)
-      {
-        partialDataSize_ = 0;
-        socket_.async_receive(boost::asio::buffer(inputBuffer_, MAX_LENGTH), 0,
-                              func_lib::bind(&Impl::handle_async_receive, this, _1, _2));
-
-        transport_.isConnected_ = true;
-
-        for (std::list<Block>::iterator i = sendQueue_.begin(); i != sendQueue_.end(); ++i)
-          socket_.async_send(boost::asio::buffer(i->wire(), i->size()),
-                             func_lib::bind(&Impl::handle_async_send, this, _1, *i));
-
-        sendQueue_.clear();
-      }
-    else
-      {
-        // may need to throw exception
-        transport_.isConnected_ = false;
-        transport_.close();
-        throw Transport::Error(error, "error while connecting to the forwarder");
-      }
-  }
-
-  void
-  connectTimeoutHandler(const boost::system::error_code& error)
-  {
-    if (error) // e.g., cancelled timer
-      return;
-
-    connectionInProgress_ = false;
-    transport_.isConnected_ = false;
-    socket_.close();
-    throw Transport::Error(error, "error while connecting to the forwarder");
-  }
-
-  void
-  resolveHandler(const boost::system::error_code& error,
-                 boost::asio::ip::tcp::resolver::iterator endpoint,
-                 const ptr_lib::shared_ptr<boost::asio::ip::tcp::resolver>&)
-  {
-    if (error)
-      {
-        if (error == boost::system::errc::operation_canceled)
-          return;
-        
-        throw Transport::Error(error, "Error during resolution of host or port [" + transport_.host_ + ":" + transport_.port_ + "]");
-      }
-    
-    boost::asio::ip::tcp::resolver::iterator end;
-    if (endpoint == end)
-      {
-        connectionInProgress_ = false;
-        transport_.isConnected_ = false;
-        socket_.close();
-        throw Transport::Error(error, "Unable to connect because host or port [" + transport_.host_ + ":" + transport_.port_ + "] cannot be resolved");
-      }
-
-    socket_.async_connect(*endpoint,
-                          func_lib::bind(&Impl::connectHandler, this, _1));
-  }
-  
-  void
-  connect()
-  {
-    if (!connectionInProgress_) {
-      connectionInProgress_ = true;
-
-      // Wait at most 4 seconds to connect
-      /// @todo Decide whether this number should be configurable
-      connectTimer_.expires_from_now(boost::posix_time::seconds(4));
-      connectTimer_.async_wait(func_lib::bind(&Impl::connectTimeoutHandler, this, _1));
-      
-      using boost::asio::ip::tcp;
-      
-      ptr_lib::shared_ptr<tcp::resolver> resolver =
-        ptr_lib::make_shared<tcp::resolver>(boost::ref(*transport_.ioService_));
-
-      tcp::resolver::query query(transport_.host_, transport_.port_);
-
-      resolver->async_resolve(query, func_lib::bind(&Impl::resolveHandler, this, _1, _2, resolver));
-    }
-  }
-
-  void 
-  close()
-  {
-    connectTimer_.cancel();
-    socket_.close();
-    transport_.isConnected_ = false;
-  }
-
-  void 
-  send(const Block &wire)
-  {
-    if (!transport_.isConnected_)
-      sendQueue_.push_back(wire);
-    else
-      socket_.async_send(boost::asio::buffer(wire.wire(), wire.size()),
-                         func_lib::bind(&Impl::handle_async_send, this, _1, wire));
-  }
-
-  inline void
-  processAll(uint8_t *buffer, size_t &offset, size_t availableSize)
-  {
-    while(offset < availableSize)
-      {
-        Block element(buffer + offset, availableSize - offset);
-        transport_.receive(element);
-
-        offset += element.size();
-      }
-  }
-  
-  void
-  handle_async_receive(const boost::system::error_code& error, std::size_t bytes_recvd)
-  {
-    /// @todo The socket is not datagram, so need to have internal buffer to handle partial data reception
-
-    if (error)
-      {
-        if (error == boost::system::errc::operation_canceled) {
-          // async receive has been explicitly cancelled (e.g., socket close)
-          return;
-        }
-        
-        socket_.close(); // closing at this point may not be that necessary
-        transport_.isConnected_ = true;
-        throw Transport::Error(error, "error while receiving data from socket");
-      }
-    
-    if (!error && bytes_recvd > 0)
-      {
-        // inputBuffer_ has bytes_recvd received bytes of data
-        if (partialDataSize_ > 0)
-          {
-            size_t newDataSize = std::min(bytes_recvd, MAX_LENGTH-partialDataSize_);
-            std::copy(inputBuffer_, inputBuffer_ + newDataSize, partialData_ + partialDataSize_);
-
-            partialDataSize_ += newDataSize;
-              
-            size_t offset = 0;
-            try
-              {
-                processAll(partialData_, offset, partialDataSize_);
-
-                // no exceptions => processed the whole thing
-                if (bytes_recvd - newDataSize > 0)
-                  {
-                    // there is a little bit more data available
-                        
-                    offset = 0;
-                    partialDataSize_ = bytes_recvd - newDataSize;
-                    std::copy(inputBuffer_ + newDataSize, inputBuffer_ + newDataSize + partialDataSize_, partialData_);
-
-                    processAll(partialData_, offset, partialDataSize_);
-
-                    // no exceptions => processed the whole thing
-                    partialDataSize_ = 0;
-                  }
-                else
-                  {
-                    // done processing
-                    partialDataSize_ = 0;
-                  }
-              }
-            catch(Tlv::Error &)
-              {
-                if (offset > 0)
-                  {
-                    partialDataSize_ -= offset;
-                    std::copy(partialData_ + offset, partialData_ + offset + partialDataSize_, partialData_);
-                  }
-                else if (offset == 0 && partialDataSize_ == MAX_LENGTH)
-                  {
-                    // very bad... should close connection
-                    socket_.close();
-                    transport_.isConnected_ = true;
-                    throw Transport::Error(boost::system::error_code(), "input buffer full, but a valid TLV cannot be decoded");
-                  }
-              }
-          }
-        else
-          {
-            size_t offset = 0;
-            try
-              {
-                processAll(inputBuffer_, offset, bytes_recvd);
-              }
-            catch(Tlv::Error &error)
-              {
-                if (offset > 0)
-                  {
-                    partialDataSize_ = bytes_recvd - offset;
-                    std::copy(inputBuffer_ + offset, inputBuffer_ + offset + partialDataSize_, partialData_);
-                  }
-              }
-          }
-      }
-
-    socket_.async_receive(boost::asio::buffer(inputBuffer_, MAX_LENGTH), 0,
-                          func_lib::bind(&Impl::handle_async_receive, this, _1, _2));
-  }
-
-  void
-  handle_async_send(const boost::system::error_code& error, const Block &wire)
-  {
-    // pass (needed to keep data block alive during the send)
-  }
-  
-private:
-  TcpTransport &transport_;
-  
-  protocol::socket socket_;
-  uint8_t inputBuffer_[MAX_LENGTH];
-
-  uint8_t partialData_[MAX_LENGTH];
-  size_t partialDataSize_;
-
-  std::list< Block > sendQueue_;
-  bool connectionInProgress_;
-
-  boost::asio::deadline_timer connectTimer_;
-};
-
 TcpTransport::TcpTransport(const std::string& host, const std::string& port/* = "6363"*/)
-  : host_(host)
-  , port_(port)
+  : m_host(host)
+  , m_port(port)
 {
 }
 
@@ -274,27 +22,36 @@
 }
 
 void 
-TcpTransport::connect(boost::asio::io_service &ioService,
-                      const ReceiveCallback &receiveCallback)
+TcpTransport::connect(boost::asio::io_service& ioService,
+                      const ReceiveCallback& receiveCallback)
 {
-  if (!static_cast<bool>(impl_)) {
+  if (!static_cast<bool>(m_impl)) {
     Transport::connect(ioService, receiveCallback);
   
-    impl_ = ptr_lib::make_shared<TcpTransport::Impl> (ptr_lib::ref(*this));
+    m_impl = make_shared<Impl> (boost::ref(*this),
+                                boost::ref(ioService));
   }
-  impl_->connect();
+
+  boost::asio::ip::tcp::resolver::query query(m_host, m_port);
+  m_impl->connect(query);
 }
 
 void 
-TcpTransport::send(const Block &wire)
+TcpTransport::send(const Block& wire)
 {
-  impl_->send(wire);
+  m_impl->send(wire);
+}
+
+void
+TcpTransport::send(const Block& header, const Block& payload)
+{
+  m_impl->send(header, payload);
 }
 
 void 
 TcpTransport::close()
 {
-  impl_->close();
+  m_impl->close();
 }
 
-}
+} // namespace ndn
diff --git a/src/transport/tcp-transport.hpp b/src/transport/tcp-transport.hpp
index c2ba56e..b97e2a1 100644
--- a/src/transport/tcp-transport.hpp
+++ b/src/transport/tcp-transport.hpp
@@ -1,18 +1,24 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
 /**
- * Copyright (C) 2013 Regents of the University of California.
- * @author: Jeff Thompson <jefft0@remap.ucla.edu>
+ * Copyright (C) 2013-2014 Regents of the University of California.
  * See COPYING for copyright and distribution information.
  */
 
-#ifndef NDN_TCP_TRANSPORT_HPP
-#define NDN_TCP_TRANSPORT_HPP
+#ifndef NDN_TRANSPORT_TCP_TRANSPORT_HPP
+#define NDN_TRANSPORT_TCP_TRANSPORT_HPP
 
 #include "../common.hpp"
 #include "transport.hpp"
 
+// forward declaration
+namespace boost { namespace asio { namespace ip { class tcp; } } }
+
 namespace ndn {
-  
+
+// forward declaration
+template<class T, class U> class StreamTransportImpl;
+template<class T, class U> class StreamTransportWithResolverImpl;
+
 class TcpTransport : public Transport
 {
 public:
@@ -21,23 +27,28 @@
 
   // from Transport
   virtual void 
-  connect(boost::asio::io_service &ioService,
-          const ReceiveCallback &receiveCallback);
+  connect(boost::asio::io_service& ioService,
+          const ReceiveCallback& receiveCallback);
   
   virtual void 
   close();
 
   virtual void 
-  send(const Block &wire);
-  
-private:
-  std::string host_;
-  std::string port_;
+  send(const Block& wire);
 
-  class Impl;
-  ptr_lib::shared_ptr<Impl> impl_;
+  virtual void 
+  send(const Block& header, const Block& payload);
+
+private:
+  std::string m_host;
+  std::string m_port;
+
+  typedef StreamTransportWithResolverImpl<TcpTransport, boost::asio::ip::tcp> Impl;
+  friend class StreamTransportImpl<TcpTransport, boost::asio::ip::tcp>;
+  friend class StreamTransportWithResolverImpl<TcpTransport, boost::asio::ip::tcp>;
+  shared_ptr< Impl > m_impl;
 };
 
-}
+} // namespace ndn
 
-#endif // NDN_TCP_TRANSPORT_HPP
+#endif // NDN_TRANSPORT_TCP_TRANSPORT_HPP
diff --git a/src/transport/transport.hpp b/src/transport/transport.hpp
index 3b62a21..c309288 100644
--- a/src/transport/transport.hpp
+++ b/src/transport/transport.hpp
@@ -1,12 +1,11 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
 /**
  * Copyright (C) 2013 Regents of the University of California.
- * @author: Jeff Thompson <jefft0@remap.ucla.edu>
  * See COPYING for copyright and distribution information.
  */
 
-#ifndef NDN_TRANSPORT_HPP
-#define NDN_TRANSPORT_HPP
+#ifndef NDN_TRANSPORT_TRANSPORT_HPP
+#define NDN_TRANSPORT_TRANSPORT_HPP
 
 #include "../common.hpp"
 #include "../encoding/block.hpp"
@@ -32,44 +31,54 @@
    * @throws If connection cannot be established
    */
   inline virtual void 
-  connect(boost::asio::io_service &io_service,
-          const ReceiveCallback &receiveCallback);
+  connect(boost::asio::io_service& io_service,
+          const ReceiveCallback& receiveCallback);
   
   /**
    * Close the connection.
    */
   virtual void 
-  close() = 0;
+  close() =0;
 
   /**
-   * Set data to the host
+   * @brief Set data to the host
+   *
    * @param data A pointer to the buffer of data to send.
    * @param dataLength The number of bytes in data.
    */
   virtual void 
-  send(const Block &wire) = 0;
+  send(const Block& wire) =0;
 
+  /**
+   * @brief Alternative version of sending data, applying scatter/gather I/O concept
+   *
+   * Two non-consecutive memory blocks will be send out together, e.g., as part of the
+   * same message in datagram-oriented transports.
+   */
+  virtual void 
+  send(const Block& header, const Block& payload) =0;
+  
   inline bool 
   isConnected();
 
 protected:
   inline void
-  receive(const Block &wire);
+  receive(const Block& wire);
   
 protected:
-  boost::asio::io_service *ioService_;
-  bool isConnected_;
-  ReceiveCallback receiveCallback_;
+  boost::asio::io_service* m_ioService;
+  bool m_isConnected;
+  ReceiveCallback m_receiveCallback;
 };
 
 inline
 Transport::Transport()
-  : ioService_(0)
-  , isConnected_(false)
+  : m_ioService(0)
+  , m_isConnected(false)
 {
 }
 
-inline Transport::Error::Error(const boost::system::error_code &code, const std::string &msg)
+inline Transport::Error::Error(const boost::system::error_code& code, const std::string& msg)
   : std::runtime_error(msg + (code.value() ? " (" + code.category().message(code.value()) + ")" : ""))
 {
 }
@@ -80,25 +89,25 @@
 }
 
 inline void 
-Transport::connect(boost::asio::io_service &ioService,
-                   const ReceiveCallback &receiveCallback)
+Transport::connect(boost::asio::io_service& ioService,
+                   const ReceiveCallback& receiveCallback)
 {
-  ioService_ = &ioService;
-  receiveCallback_ = receiveCallback;
+  m_ioService = &ioService;
+  m_receiveCallback = receiveCallback;
 }
 
 inline bool 
 Transport::isConnected()
 {
-  return isConnected_;
+  return m_isConnected;
 }
 
 inline void
-Transport::receive(const Block &wire)
+Transport::receive(const Block& wire)
 {
-  receiveCallback_(wire);
+  m_receiveCallback(wire);
 }
 
-}
+} // namespace ndn
 
-#endif
+#endif // NDN_TRANSPORT_TRANSPORT_HPP
diff --git a/src/transport/unix-transport.cpp b/src/transport/unix-transport.cpp
index 84424f3..f1e26ec 100644
--- a/src/transport/unix-transport.cpp
+++ b/src/transport/unix-transport.cpp
@@ -1,246 +1,28 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
 /**
- * Copyright (C) 2013 Regents of the University of California.
- * @author: Jeff Thompson <jefft0@remap.ucla.edu>
+ * Copyright (C) 2013-2014 Regents of the University of California.
  * See COPYING for copyright and distribution information.
  */
 
 #include "common.hpp"
 
 #include "unix-transport.hpp"
+#include "stream-transport.hpp"
 
 #include "../face.hpp"
-#include <cstdlib>
-
-using namespace std;
-typedef boost::asio::local::stream_protocol protocol;
 
 namespace ndn {
 
-const size_t MAX_LENGTH = 9000;
-
-class UnixTransport::Impl
-{
-public:
-  Impl(UnixTransport &transport)
-    : transport_(transport)
-    , socket_(*transport_.ioService_)
-    , partialDataSize_(0)
-    , connectionInProgress_(false)
-    , connectTimer_(*transport_.ioService_)
-  {
-  }
-
-  void
-  connectHandler(const boost::system::error_code& error)
-  {
-    connectionInProgress_ = false;
-    connectTimer_.cancel();
-
-    if (!error)
-      {
-        partialDataSize_ = 0;
-        socket_.async_receive(boost::asio::buffer(inputBuffer_, MAX_LENGTH), 0,
-                              func_lib::bind(&Impl::handle_async_receive, this, _1, _2));
-
-        transport_.isConnected_ = true;
-
-        for (std::list<Block>::iterator i = sendQueue_.begin(); i != sendQueue_.end(); ++i)
-          socket_.async_send(boost::asio::buffer(i->wire(), i->size()),
-                             func_lib::bind(&Impl::handle_async_send, this, _1, *i));
-
-        sendQueue_.clear();
-      }
-    else
-      {
-        // may need to throw exception
-        transport_.isConnected_ = false;
-        transport_.close();
-        throw Transport::Error(error, "error while connecting to the forwarder");
-      }
-  }
-
-  void
-  connectTimeoutHandler(const boost::system::error_code& error)
-  {
-    if (error) // e.g., cancelled timer
-      return;
-
-    connectionInProgress_ = false;
-    transport_.isConnected_ = false;
-    socket_.close();
-    throw Transport::Error(error, "error while connecting to the forwarder");
-  }
-
-  void
-  connect()
-  {
-    if (!connectionInProgress_) {
-      connectionInProgress_ = true;
-
-      // Wait at most 4 seconds to connect
-      /// @todo Decide whether this number should be configurable
-      connectTimer_.expires_from_now(boost::posix_time::seconds(4));
-      connectTimer_.async_wait(func_lib::bind(&Impl::connectTimeoutHandler, this, _1));
-
-      socket_.open();
-      socket_.async_connect(protocol::endpoint(transport_.unixSocket_),
-                            func_lib::bind(&Impl::connectHandler, this, _1));
-    }
-  }
-
-  void
-  close()
-  {
-    connectTimer_.cancel();
-    socket_.close();
-    transport_.isConnected_ = false;
-  }
-
-  void
-  send(const Block& wire)
-  {
-    if (!transport_.isConnected_)
-      sendQueue_.push_back(wire);
-    else
-      socket_.async_send(boost::asio::buffer(wire.wire(), wire.size()),
-                         func_lib::bind(&Impl::handle_async_send, this, _1, wire));
-  }
-
-  inline void
-  processAll(uint8_t* buffer, size_t& offset, size_t availableSize)
-  {
-    while(offset < availableSize)
-      {
-        Block element(buffer + offset, availableSize - offset);
-        transport_.receive(element);
-
-        offset += element.size();
-      }
-  }
-
-  void
-  handle_async_receive(const boost::system::error_code& error, std::size_t bytes_recvd)
-  {
-    /// @todo The socket is not datagram, so need to have internal buffer to handle partial data reception
-
-    if (error)
-      {
-        if (error == boost::system::errc::operation_canceled) {
-          // async receive has been explicitly cancelled (e.g., socket close)
-          return;
-        }
-
-        socket_.close(); // closing at this point may not be that necessary
-        transport_.isConnected_ = true;
-        throw Transport::Error(error, "error while receiving data from socket");
-      }
-
-    if (!error && bytes_recvd > 0)
-      {
-        // inputBuffer_ has bytes_recvd received bytes of data
-        if (partialDataSize_ > 0)
-          {
-            size_t newDataSize = std::min(bytes_recvd, MAX_LENGTH-partialDataSize_);
-            std::copy(inputBuffer_, inputBuffer_ + newDataSize, partialData_ + partialDataSize_);
-
-            partialDataSize_ += newDataSize;
-
-            size_t offset = 0;
-            try
-              {
-                processAll(partialData_, offset, partialDataSize_);
-
-                // no exceptions => processed the whole thing
-                if (bytes_recvd - newDataSize > 0)
-                  {
-                    // there is a little bit more data available
-
-                    offset = 0;
-                    partialDataSize_ = bytes_recvd - newDataSize;
-                    std::copy(inputBuffer_ + newDataSize, inputBuffer_ + newDataSize + partialDataSize_, partialData_);
-
-                    processAll(partialData_, offset, partialDataSize_);
-
-                    // no exceptions => processed the whole thing
-                    partialDataSize_ = 0;
-                  }
-                else
-                  {
-                    // done processing
-                    partialDataSize_ = 0;
-                  }
-              }
-            catch(Tlv::Error &)
-              {
-                if (offset > 0)
-                  {
-                    partialDataSize_ -= offset;
-                    std::copy(partialData_ + offset, partialData_ + offset + partialDataSize_, partialData_);
-                  }
-                else if (offset == 0 && partialDataSize_ == MAX_LENGTH)
-                  {
-                    // very bad... should close connection
-                    socket_.close();
-                    transport_.isConnected_ = true;
-                    throw Transport::Error(boost::system::error_code(), "input buffer full, but a valid TLV cannot be decoded");
-                  }
-              }
-          }
-        else
-          {
-            size_t offset = 0;
-            try
-              {
-                processAll(inputBuffer_, offset, bytes_recvd);
-              }
-            catch(Tlv::Error &error)
-              {
-                if (offset > 0)
-                  {
-                    partialDataSize_ = bytes_recvd - offset;
-                    std::copy(inputBuffer_ + offset, inputBuffer_ + offset + partialDataSize_, partialData_);
-                  }
-              }
-          }
-      }
-
-    socket_.async_receive(boost::asio::buffer(inputBuffer_, MAX_LENGTH), 0,
-                          func_lib::bind(&Impl::handle_async_receive, this, _1, _2));
-  }
-
-  void
-  handle_async_send(const boost::system::error_code& error, const Block &wire)
-  {
-    // pass (needed to keep data block alive during the send)
-  }
-
-private:
-  UnixTransport &transport_;
-
-  protocol::socket socket_;
-  uint8_t inputBuffer_[MAX_LENGTH];
-
-  uint8_t partialData_[MAX_LENGTH];
-  size_t partialDataSize_;
-
-  std::list< Block > sendQueue_;
-  bool connectionInProgress_;
-
-  boost::asio::deadline_timer connectTimer_;
-};
-
-
 UnixTransport::UnixTransport()
 {
   if (std::getenv("NFD") != 0)
-      unixSocket_ = "/var/run/nfd.sock";
+      m_unixSocket = "/var/run/nfd.sock";
   else
-      unixSocket_ = "/tmp/.ndnd.sock";
+      m_unixSocket = "/tmp/.ndnd.sock";
 }
 
 UnixTransport::UnixTransport(const std::string& unixSocket)
-  : unixSocket_(unixSocket)
+  : m_unixSocket(unixSocket)
 {
 }
 
@@ -252,24 +34,32 @@
 UnixTransport::connect(boost::asio::io_service& ioService,
                        const ReceiveCallback& receiveCallback)
 {
-  if (!static_cast<bool>(impl_)) {
+  if (!static_cast<bool>(m_impl)) {
     Transport::connect(ioService, receiveCallback);
 
-    impl_ = ptr_lib::make_shared<UnixTransport::Impl> (ptr_lib::ref(*this));
+    m_impl = make_shared<Impl> (boost::ref(*this),
+                                boost::ref(ioService));
   }
-  impl_->connect();
+
+  m_impl->connect(boost::asio::local::stream_protocol::endpoint(m_unixSocket));
 }
 
 void
 UnixTransport::send(const Block& wire)
 {
-  impl_->send(wire);
+  m_impl->send(wire);
+}
+
+void
+UnixTransport::send(const Block& header, const Block& payload)
+{
+  m_impl->send(header, payload);
 }
 
 void
 UnixTransport::close()
 {
-  impl_->close();
+  m_impl->close();
 }
 
 }
diff --git a/src/transport/unix-transport.hpp b/src/transport/unix-transport.hpp
index dc85eac..4a89bc8 100644
--- a/src/transport/unix-transport.hpp
+++ b/src/transport/unix-transport.hpp
@@ -1,7 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
 /**
- * Copyright (C) 2013 Regents of the University of California.
- * @author: Jeff Thompson <jefft0@remap.ucla.edu>
+ * Copyright (C) 2013-2014 Regents of the University of California.
  * See COPYING for copyright and distribution information.
  */
 
@@ -11,8 +10,15 @@
 #include "../common.hpp"
 #include "transport.hpp"
 
+// forward declaration
+namespace boost { namespace asio { namespace local { class stream_protocol; } } }
+
 namespace ndn {
 
+// forward declaration
+template<class T, class U>
+class StreamTransportImpl;
+
 class UnixTransport : public Transport
 {
 public:
@@ -32,11 +38,15 @@
   virtual void
   send(const Block& wire);
 
+  virtual void
+  send(const Block& header, const Block& payload);
+  
 private:
-  std::string unixSocket_;
+  std::string m_unixSocket;
 
-  class Impl;
-  ptr_lib::shared_ptr<Impl> impl_;
+  typedef StreamTransportImpl<UnixTransport, boost::asio::local::stream_protocol> Impl;
+  friend class StreamTransportImpl<UnixTransport, boost::asio::local::stream_protocol>;
+  ptr_lib::shared_ptr< Impl > m_impl;
 };
 
 }