audk/StdLib/EfiSocketLib/Tcp4.c

/** @file
  Implement the TCP4 driver support for the socket layer.

  Copyright (c) 2011, Intel Corporation
  All rights reserved. This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.


  \section ConnectionManagement Connection Management
  
  The ::EslTcp4Listen routine initially places the SOCK_STREAM or
  SOCK_SEQPACKET socket into a listen state.   When a remote machine
  makes a connection to the socket, the TCPv4 network layer calls
  ::EslTcp4ListenComplete to complete the connection processing.
  EslTcp4ListenComplete manages the connections by placing them in
  FIFO order in a queue to be serviced by the application.  When the
  number of connections exceeds the backlog (ESL_SOCKET::MaxFifoDepth),
  the new connection is closed.  Eventually, the application indirectly
  calls ::EslTcp4Accept to remove the next connection from the queue
  and get the associated socket.

**/

#include "Socket.h"


/**
  Attempt to connect to a remote TCP port

  This routine starts the connection processing for a SOCK_STREAM
  or SOCK_SEQPAKCET socket using the TCPv4 network layer.  It
  configures the local TCPv4 connection point and then attempts to
  connect to a remote system.  Upon completion, the
  ::EslTcp4ConnectComplete routine gets called with the connection
  status.

  This routine is called by ::EslSocketConnect to initiate the TCPv4
  network specific connect operations.  The connection processing is
  initiated by this routine and finished by ::EslTcp4ConnectComplete.
  This pair of routines walks through the list of local TCPv4
  connection points until a connection to the remote system is
  made.

  @param [in] pSocket   Address of an ::ESL_SOCKET structure.

  @retval EFI_SUCCESS   The connection was successfully established.
  @retval EFI_NOT_READY The connection is in progress, call this routine again.
  @retval Others        The connection attempt failed.

 **/
EFI_STATUS
EslTcp4ConnectStart (
  IN ESL_SOCKET * pSocket
  );


/**
  Process the connection attempt

  A system has initiated a connection attempt with a socket in the
  listen state.  Attempt to complete the connection.

  The TCPv4 layer calls this routine when a connection is made to
  the socket in the listen state.  See the
  \ref ConnectionManagement section.

  @param [in] Event     The listen completion event

  @param [in] pPort     Address of an ::ESL_PORT structure.

**/
VOID
EslTcp4ListenComplete (
  IN EFI_EVENT Event,
  IN ESL_PORT * pPort
  );


/**
  Accept a network connection.

  This routine waits for a network connection to the socket and
  returns the remote network address to the caller if requested.

  This routine is called by ::EslSocketAccept to handle the TCPv4 protocol
  specific accept operations for SOCK_STREAM and SOCK_SEQPACKET sockets.
  See the \ref ConnectionManagement section.

  @param [in] pSocket   Address of an ::ESL_SOCKET structure.

  @param [in] pSockAddr       Address of a buffer to receive the remote
                              network address.

  @param [in, out] pSockAddrLength  Length in bytes of the address buffer.
                                    On output specifies the length of the
                                    remote network address.

  @retval EFI_SUCCESS   Remote address is available
  @retval Others        Remote address not available

 **/
EFI_STATUS
EslTcp4Accept (
  IN ESL_SOCKET * pSocket,
  IN struct sockaddr * pSockAddr,
  IN OUT socklen_t * pSockAddrLength
  )
{
  ESL_PORT * pPort;
  struct sockaddr_in * pRemoteAddress;
  ESL_TCP4_CONTEXT * pTcp4;
  UINT32 RemoteAddress;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Validate the socket length
  //
  pRemoteAddress = (struct sockaddr_in *) pSockAddr;
  if (( NULL == pSockAddrLength )
    || ( sizeof ( *pRemoteAddress ) > *pSockAddrLength )) {
    //
    //  Invalid socket address
    //
    Status = EFI_INVALID_PARAMETER;
    pSocket->errno = EINVAL;
    DEBUG (( DEBUG_ACCEPT,
              "ERROR - Invalid address length\r\n" ));
  }
  else {
    //
    //  Assume success
    //
    Status = EFI_SUCCESS;

    //
    //  Locate the address context
    //
    pPort = pSocket->pPortList;
    pTcp4 = &pPort->Context.Tcp4;

    //
    //  Fill-in the remote address structure
    //
    ZeroMem ( pRemoteAddress, sizeof ( *pRemoteAddress ));
    pRemoteAddress->sin_len = sizeof ( *pRemoteAddress );
    pRemoteAddress->sin_family = AF_INET;
    pRemoteAddress->sin_port = SwapBytes16 ( pTcp4->ConfigData.AccessPoint.RemotePort );
    RemoteAddress = pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[3];
    RemoteAddress <<= 8;
    RemoteAddress |= pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[2];
    RemoteAddress <<= 8;
    RemoteAddress |= pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[1];
    RemoteAddress <<= 8;
    RemoteAddress |= pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[0];
    pRemoteAddress->sin_addr.s_addr = RemoteAddress;
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Process the remote connection completion event.

  This routine handles the completion of a connection attempt.  It
  releases the port (TCPv4 adapter connection) in the case of an
  error and start a connection attempt on the next port.  If the
  connection attempt was successful then this routine releases all
  of the other ports.

  This routine is called by the TCPv4 layer when a connect request
  completes.  It sets the ESL_SOCKET::bConnected flag to notify the
  ::EslTcp4ConnectComplete routine that the connection is available.
  The flag is set when the connection is established or no more ports
  exist in the list.  The connection status is passed via
  ESL_SOCKET::ConnectStatus.

  @param [in] Event     The connect completion event

  @param [in] pPort     Address of an ::ESL_PORT structure.

**/
VOID
EslTcp4ConnectComplete (
  IN EFI_EVENT Event,
  IN ESL_PORT * pPort
  )
{
  BOOLEAN bRemoveFirstPort;
  BOOLEAN bRemovePorts;
  ESL_PORT * pNextPort;
  ESL_SOCKET * pSocket;
  ESL_TCP4_CONTEXT * pTcp4;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Locate the TCP context
  //
  pSocket = pPort->pSocket;
  pTcp4 = &pPort->Context.Tcp4;

  //
  //  Get the connection status
  //
  bRemoveFirstPort = FALSE;
  bRemovePorts = FALSE;
  Status = pTcp4->ConnectToken.CompletionToken.Status;
  pSocket->ConnectStatus = Status;
  if ( !EFI_ERROR ( Status )) {
    //
    //  The connection was successful
    //
    DEBUG (( DEBUG_CONNECT,
              "0x%08x: Port connected to %d.%d.%d.%d:%d\r\n",
              pPort,
              pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[0],
              pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[1],
              pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[2],
              pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[3],
              pTcp4->ConfigData.AccessPoint.RemotePort ));

    //
    //  Remove the rest of the ports
    //
    bRemovePorts = TRUE;
  }
  else {
    //
    //  The connection failed
    //
    if ( pPort->bConfigured ) {
      DEBUG (( DEBUG_CONNECT,
                "0x%08x: Port connection to %d.%d.%d.%d:%d failed, Status: %r\r\n",
                pPort,
                pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[0],
                pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[1],
                pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[2],
                pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[3],
                pTcp4->ConfigData.AccessPoint.RemotePort,
                Status ));
    }

    //
    //  Close the current port
    //
    Status = EslSocketPortClose ( pPort );
    if ( !EFI_ERROR ( Status )) {
      DEBUG (( DEBUG_CONNECT,
              "0x%08x: Port closed\r\n",
              pPort ));
    }
    else {
      DEBUG (( DEBUG_CONNECT,
                "ERROR - Failed to close port 0x%08x, Status: %r\r\n",
                pPort,
                Status ));
    }

    //
    //  Try to connect using the next port
    //
    Status = EslTcp4ConnectStart ( pSocket );
    if ( EFI_NOT_READY != Status ) {
      bRemoveFirstPort = TRUE;
    }
  }

  //
  //  Remove the ports if necessary
  //
  if ( bRemoveFirstPort || bRemovePorts ) {
    //
    //  Remove the first port if necessary
    //
    pPort = pSocket->pPortList;
    if (( !bRemoveFirstPort ) && ( NULL != pPort )) {
      pPort = pPort->pLinkSocket;
    }

    //
    //  Remove the rest of the list
    //
    while ( NULL != pPort ) {
      pNextPort = pPort->pLinkSocket;
      EslSocketPortClose ( pPort );
      if ( !EFI_ERROR ( Status )) {
        DEBUG (( DEBUG_CONNECT,
                "0x%08x: Port closed\r\n",
                pPort ));
      }
      else {
        DEBUG (( DEBUG_CONNECT,
                  "ERROR - Failed to close port 0x%08x, Status: %r\r\n",
                  pPort,
                  Status ));
      }
      pPort = pNextPort;
    }

    //
    //  Notify the poll routine
    //
    pSocket->bConnected = TRUE;
  }

  DBG_EXIT ( );
}


/**
  Poll for completion of the connection attempt.

  This routine polls the ESL_SOCKET::bConnected flag to determine
  when the connection attempt is complete.

  This routine is called from ::EslSocketConnect to determine when
  the connection is complete.  The ESL_SOCKET::bConnected flag is
  set by ::EslTcp4ConnectComplete when the TCPv4 layer establishes
  a connection or runs out of local network adapters.  This routine
  gets the connection status from ESL_SOCKET::ConnectStatus.

  @param [in] pSocket   Address of an ::ESL_SOCKET structure.

  @retval EFI_SUCCESS   The connection was successfully established.
  @retval EFI_NOT_READY The connection is in progress, call this routine again.
  @retval Others        The connection attempt failed.

 **/
EFI_STATUS
EslTcp4ConnectPoll (
  IN ESL_SOCKET * pSocket
  )
{
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Determine if the connection is complete
  //
  if ( !pSocket->bConnected ) {
    //
    //  Not connected
    //
    pSocket->errno = EAGAIN;
    Status = EFI_NOT_READY;
  }
  else {
    //
    //  The connection processing is complete
    //
    pSocket->bConnected = FALSE;

    //
    //  Translate the connection status
    //
    Status = pSocket->ConnectStatus;
    switch ( Status ) {
    default:
    case EFI_DEVICE_ERROR:
      pSocket->errno = EIO;
      break;

    case EFI_ABORTED:
      pSocket->errno = ECONNABORTED;
      break;

    case EFI_ACCESS_DENIED:
      pSocket->errno = EACCES;
      break;

    case EFI_CONNECTION_RESET:
      pSocket->errno = ECONNRESET;
      break;

    case EFI_INVALID_PARAMETER:
      pSocket->errno = EADDRNOTAVAIL;
      break;

    case EFI_HOST_UNREACHABLE:
    case EFI_NO_RESPONSE:
      pSocket->errno = EHOSTUNREACH;
      break;

    case EFI_NO_MAPPING:
      pSocket->errno = EAFNOSUPPORT;
      break;

    case EFI_NO_MEDIA:
    case EFI_NETWORK_UNREACHABLE:
      pSocket->errno = ENETDOWN;
      break;

    case EFI_OUT_OF_RESOURCES:
      pSocket->errno = ENOBUFS;
      break;

    case EFI_PORT_UNREACHABLE:
    case EFI_PROTOCOL_UNREACHABLE:
    case EFI_CONNECTION_REFUSED:
      pSocket->errno = ECONNREFUSED;
      break;

    case EFI_SUCCESS:
      pSocket->errno = 0;
      pSocket->bConfigured = TRUE;
      break;

    case EFI_TIMEOUT:
      pSocket->errno = ETIMEDOUT;
      break;

    case EFI_UNSUPPORTED:
      pSocket->errno = EOPNOTSUPP;
      break;
    }

    //
    //  Display the translation
    //
    DEBUG (( DEBUG_CONNECT,
              "ERROR - errno: %d, Status: %r\r\n",
              pSocket->errno,
              Status ));
  }

  //
  //  Return the initialization status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Attempt to connect to a remote TCP port

  This routine starts the connection processing for a SOCK_STREAM
  or SOCK_SEQPAKCET socket using the TCPv4 network layer.  It
  configures the local TCPv4 connection point and then attempts to
  connect to a remote system.  Upon completion, the
  ::EslTcp4ConnectComplete routine gets called with the connection
  status.

  This routine is called by ::EslSocketConnect to initiate the TCPv4
  network specific connect operations.  The connection processing is
  initiated by this routine and finished by ::EslTcp4ConnectComplete.
  This pair of routines walks through the list of local TCPv4
  connection points until a connection to the remote system is
  made.

  @param [in] pSocket   Address of an ::ESL_SOCKET structure.

  @retval EFI_SUCCESS   The connection was successfully established.
  @retval EFI_NOT_READY The connection is in progress, call this routine again.
  @retval Others        The connection attempt failed.

 **/
EFI_STATUS
EslTcp4ConnectStart (
  IN ESL_SOCKET * pSocket
  )
{
  ESL_PORT * pPort;
  ESL_TCP4_CONTEXT * pTcp4;
  EFI_TCP4_PROTOCOL * pTcp4Protocol;
  EFI_SIMPLE_NETWORK_MODE SnpModeData;
  EFI_STATUS Status;

  DBG_ENTER ( );
  
  //
  //  Determine if any more local adapters are available
  //
  pPort = pSocket->pPortList;
  if ( NULL != pPort ) {
    //
    //  Configure the port
    //
    pTcp4 = &pPort->Context.Tcp4;
    pTcp4->ConfigData.AccessPoint.ActiveFlag = TRUE;
    pTcp4->ConfigData.TimeToLive = 255;
    pTcp4Protocol = pPort->pProtocol.TCPv4;
    Status = pTcp4Protocol->Configure ( pTcp4Protocol,
                                        &pTcp4->ConfigData );
    if ( EFI_ERROR ( Status )) {
      DEBUG (( DEBUG_CONNECT,
                "ERROR - Failed to configure the Tcp4 port, Status: %r\r\n",
                Status ));
    }
    else {
      DEBUG (( DEBUG_CONNECT,
                "0x%08x: Port configured\r\n",
                pPort ));
      pPort->bConfigured = TRUE;

      //
      //  Verify the port connection
      //
      Status = pTcp4Protocol->GetModeData ( pTcp4Protocol,
                                            NULL,
                                            NULL,
                                            NULL,
                                            NULL,
                                            &SnpModeData );
      if ( !EFI_ERROR ( Status )) {
        if ( SnpModeData.MediaPresentSupported
          && ( !SnpModeData.MediaPresent )) {
          //
          //  Port is not connected to the network
          //
          Status = EFI_NO_MEDIA;
        }
        else {
          //
          //  Attempt the connection to the remote system
          //
          Status = pTcp4Protocol->Connect ( pTcp4Protocol,
                                            &pTcp4->ConnectToken );
        }
      }
      if ( EFI_ERROR ( Status )) {
        //
        //  Connection error
        //
        DEBUG (( DEBUG_CONNECT,
                  "ERROR - Port 0x%08x not connected, Status: %r\r\n",
                  pPort,
                  Status ));
      }
    }
    if ( !EFI_ERROR ( Status )) {
      //
      //  Connection in progress
      //
      pSocket->errno = EINPROGRESS;
      DEBUG (( DEBUG_CONNECT,
                "0x%08x: Port attempting connection to %d.%d.%d.%d:%d\r\n",
                pPort,
                pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[0],
                pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[1],
                pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[2],
                pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[3],
                pTcp4->ConfigData.AccessPoint.RemotePort ));
    }
    else {
      //
      //  Error return path is through EslTcp4ConnectComplete to
      //  enable retry on other ports
      //
      //  Status to errno translation gets done in EslTcp4ConnectPoll
      //
      pTcp4->ConnectToken.CompletionToken.Status = Status;

      //
      //  Continue with the next port
      //
      gBS->CheckEvent ( pTcp4->ConnectToken.CompletionToken.Event );
      gBS->SignalEvent ( pTcp4->ConnectToken.CompletionToken.Event );
    }
    Status = EFI_NOT_READY;
  }
  else {
    //
    //  No more local adapters available
    //
    pSocket->errno = ENETUNREACH;
    Status = EFI_NO_RESPONSE;
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Establish the known port to listen for network connections.

  This routine places the port into a state that enables connection
  attempts.

  This routine is called by ::EslSocketListen to handle the network
  specifics of the listen operation for SOCK_STREAM and SOCK_SEQPACKET
  sockets.  See the \ref ConnectionManagement section.

  @param [in] pSocket   Address of an ::ESL_SOCKET structure.

  @retval EFI_SUCCESS - Socket successfully created
  @retval Other - Failed to enable the socket for listen

**/
EFI_STATUS
EslTcp4Listen (
  IN ESL_SOCKET * pSocket
  )
{
  ESL_PORT * pNextPort;
  ESL_PORT * pPort;
  ESL_TCP4_CONTEXT * pTcp4;
  EFI_TCP4_PROTOCOL * pTcp4Protocol;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Verify the socket layer synchronization
  //
  VERIFY_TPL ( TPL_SOCKETS );

  //
  //  Use for/break instead of goto
  //
  for ( ; ; ) {
    //
    //  Assume no ports are available
    //
    pSocket->errno = EOPNOTSUPP;
    Status = EFI_NOT_READY;

    //
    //  Walk the list of ports
    //
    pPort = pSocket->pPortList;
    while ( NULL != pPort ) {
      //
      //  Assume success
      //
      pSocket->errno = 0;

      //
      //  Use for/break insteak of goto
      //
      for ( ; ; ) {
        //
        //  Create the listen completion event
        //
        pTcp4 = &pPort->Context.Tcp4;
        Status = gBS->CreateEvent ( EVT_NOTIFY_SIGNAL,
                                    TPL_SOCKETS,
                                    (EFI_EVENT_NOTIFY)EslTcp4ListenComplete,
                                    pPort,
                                    &pTcp4->ListenToken.CompletionToken.Event );
        if ( EFI_ERROR ( Status )) {
          DEBUG (( DEBUG_ERROR | DEBUG_LISTEN,
                    "ERROR - Failed to create the listen completion event, Status: %r\r\n",
                    Status ));
          pSocket->errno = ENOMEM;
          break;
        }
        DEBUG (( DEBUG_POOL,
                  "0x%08x: Created listen completion event\r\n",
                  pTcp4->ListenToken.CompletionToken.Event ));

        //
        //  Configure the port
        //
        pTcp4Protocol = pPort->pProtocol.TCPv4;
        Status = pTcp4Protocol->Configure ( pTcp4Protocol,
                                            &pTcp4->ConfigData );
        if ( EFI_ERROR ( Status )) {
          DEBUG (( DEBUG_LISTEN,
                    "ERROR - Failed to configure the Tcp4 port, Status: %r\r\n",
                    Status ));
          switch ( Status ) {
          case EFI_ACCESS_DENIED:
            pSocket->errno = EACCES;
            break;

          default:
          case EFI_DEVICE_ERROR:
            pSocket->errno = EIO;
            break;

          case EFI_INVALID_PARAMETER:
            pSocket->errno = EADDRNOTAVAIL;
            break;

          case EFI_NO_MAPPING:
            pSocket->errno = EAFNOSUPPORT;
            break;

          case EFI_OUT_OF_RESOURCES:
            pSocket->errno = ENOBUFS;
            break;

          case EFI_UNSUPPORTED:
            pSocket->errno = EOPNOTSUPP;
            break;
          }
          break;
        }
        DEBUG (( DEBUG_LISTEN,
                  "0x%08x: Port configured\r\n",
                  pPort ));
        pPort->bConfigured = TRUE;

        //
        //  Start the listen operation on the port
        //
        Status = pTcp4Protocol->Accept ( pTcp4Protocol,
                                         &pTcp4->ListenToken );
        if ( EFI_ERROR ( Status )) {
          DEBUG (( DEBUG_LISTEN,
                    "ERROR - Failed Tcp4 accept, Status: %r\r\n",
                    Status ));
          switch ( Status ) {
          case EFI_ACCESS_DENIED:
            pSocket->errno = EACCES;
            break;

          default:
          case EFI_DEVICE_ERROR:
            pSocket->errno = EIO;
            break;

          case EFI_INVALID_PARAMETER:
            pSocket->errno = EADDRNOTAVAIL;
            break;

          case EFI_NOT_STARTED:
            pSocket->errno = ENETDOWN;
            break;

          case EFI_OUT_OF_RESOURCES:
            pSocket->errno = ENOBUFS;
            break;
          }
          break;
        }
        DEBUG (( DEBUG_LISTEN,
                  "0x%08x: Listen pending on Port\r\n",
                  pPort ));

        //
        //  Listen is pending on this port
        //
        break;
      }

      //
      //  Get the next port
      //
      pNextPort = pPort->pLinkSocket;

      //
      //  Close the port upon error
      //
      if ( EFI_ERROR ( Status )) {
        EslSocketPortCloseStart ( pPort, TRUE, DEBUG_LISTEN );
      }

      //
      //  Set the next port
      //
      pPort = pNextPort;
    }
    
    //
    //  Determine if any ports are in the listen state
    //
    if ( NULL == pSocket->pPortList ) {
      //
      //  No ports in the listen state
      //
      pSocket->MaxFifoDepth = 0;

      //
      //  Return the last error detected
      //
      break;
    }

    //
    //  Mark the socket as configured
    //
    pSocket->bConfigured = TRUE;
    Status = EFI_SUCCESS;
    pSocket->errno = 0;

    //
    //  All done
    //
    DEBUG (( DEBUG_LISTEN,
              "0x%08x: pSocket - Listen pending on socket\r\n",
              pSocket ));
    break;
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Process the connection attempt

  A system has initiated a connection attempt with a socket in the
  listen state.  Attempt to complete the connection.

  The TCPv4 layer calls this routine when a connection is made to
  the socket in the listen state.  See the
  \ref ConnectionManagement section.

  @param [in] Event     The listen completion event

  @param [in] pPort     Address of an ::ESL_PORT structure.

**/
VOID
EslTcp4ListenComplete (
  IN EFI_EVENT Event,
  IN ESL_PORT * pPort
  )
{
  EFI_HANDLE ChildHandle;
  struct sockaddr_in LocalAddress;
  EFI_TCP4_CONFIG_DATA * pConfigData;
  ESL_LAYER * pLayer;
  ESL_PORT * pNewPort;
  ESL_SOCKET * pNewSocket;
  ESL_SOCKET * pSocket;
  ESL_TCP4_CONTEXT * pTcp4;
  EFI_TCP4_PROTOCOL * pTcp4Protocol;
  EFI_STATUS Status;
  EFI_HANDLE TcpPortHandle;
  EFI_STATUS TempStatus;

  DBG_ENTER ( );
  VERIFY_AT_TPL ( TPL_SOCKETS );

  //
  //  Assume success
  //
  Status = EFI_SUCCESS;

  //
  //  Determine if this connection fits into the connection FIFO
  //
  pSocket = pPort->pSocket;
  TcpPortHandle = pPort->Context.Tcp4.ListenToken.NewChildHandle;
  if (( SOCKET_STATE_LISTENING == pSocket->State )
    && ( pSocket->MaxFifoDepth > pSocket->FifoDepth )) {
    //
    //  Allocate a socket for this connection
    //
    ChildHandle = NULL;
    pLayer = &mEslLayer;
    Status = EslSocketAllocate ( &ChildHandle,
                                 DEBUG_CONNECTION,
                                 &pNewSocket );
    if ( !EFI_ERROR ( Status )) {
      //
      //  Clone the socket parameters
      //
      pNewSocket->pApi = pSocket->pApi;
      pNewSocket->Domain = pSocket->Domain;
      pNewSocket->Protocol = pSocket->Protocol;
      pNewSocket->Type = pSocket->Type;

      //
      //  Build the local address
      //
      pTcp4 = &pPort->Context.Tcp4;
      LocalAddress.sin_len = (uint8_t)pNewSocket->pApi->MinimumAddressLength;
      LocalAddress.sin_family = AF_INET;
      LocalAddress.sin_port = 0;
      LocalAddress.sin_addr.s_addr = *(UINT32 *)&pTcp4->ConfigData.AccessPoint.StationAddress.Addr[0];

      //
      //  Allocate a port for this connection
      //  Note in this instance Configure may not be called with NULL!
      //
      Status = EslSocketPortAllocate ( pNewSocket,
                                       pPort->pService,
                                       TcpPortHandle,
                                       (struct sockaddr *)&LocalAddress,
                                       FALSE,
                                       DEBUG_CONNECTION,
                                       &pNewPort );
      if ( !EFI_ERROR ( Status )) {
        //
        //  Restart the listen operation on the port
        //
        pTcp4Protocol = pPort->pProtocol.TCPv4;
        Status = pTcp4Protocol->Accept ( pTcp4Protocol,
                                         &pTcp4->ListenToken );

        //
        //  Close the TCP port using SocketClose
        //
        TcpPortHandle = NULL;
        pTcp4 = &pNewPort->Context.Tcp4;

        //
        //  Check for an accept call error
        //
        if ( !EFI_ERROR ( Status )) {
          //
          //  Get the port configuration
          //
          pNewPort->bConfigured = TRUE;
          pConfigData = &pTcp4->ConfigData;
          pConfigData->ControlOption = &pTcp4->Option;
          pTcp4Protocol = pNewPort->pProtocol.TCPv4;
          Status = pTcp4Protocol->GetModeData ( pTcp4Protocol,
                                                NULL,
                                                pConfigData,
                                                NULL,
                                                NULL,
                                                NULL );
          if ( !EFI_ERROR ( Status )) {
            //
            //  Add the new socket to the connection FIFO
            //
            if ( NULL == pSocket->pFifoTail ) {
              //
              //  First connection
              //
              pSocket->pFifoHead = pNewSocket;
            }
            else {
              //
              //  Add to end of list.
              //
              pSocket->pFifoTail->pNextConnection = pNewSocket;
            }
            pSocket->pFifoTail = pNewSocket;
            pSocket->FifoDepth += 1;

            //
            //  Update the socket state
            //
            pNewSocket->State = SOCKET_STATE_IN_FIFO;

            //
            //  Log the connection
            //
            DEBUG (( DEBUG_CONNECTION | DEBUG_INFO,
                      "0x%08x: Socket on port %d.%d.%d.%d:%d connected to %d.%d.%d.%d:%d\r\n",
                      pNewSocket,
                      pConfigData->AccessPoint.StationAddress.Addr[0],
                      pConfigData->AccessPoint.StationAddress.Addr[1],
                      pConfigData->AccessPoint.StationAddress.Addr[2],
                      pConfigData->AccessPoint.StationAddress.Addr[3],
                      pConfigData->AccessPoint.StationPort,
                      pConfigData->AccessPoint.RemoteAddress.Addr[0],
                      pConfigData->AccessPoint.RemoteAddress.Addr[1],
                      pConfigData->AccessPoint.RemoteAddress.Addr[2],
                      pConfigData->AccessPoint.RemoteAddress.Addr[3],
                      pConfigData->AccessPoint.RemotePort ));
            DEBUG (( DEBUG_CONNECTION | DEBUG_INFO,
                      "0x%08x: Listen socket adding socket 0x%08x to FIFO, depth: %d\r\n",
                      pSocket,
                      pNewSocket,
                      pSocket->FifoDepth ));

            //
            //  Start the receive operation
            //
            EslSocketRxStart ( pNewPort );
          }
          else {
            DEBUG (( DEBUG_ERROR | DEBUG_CONNECTION | DEBUG_INFO,
                      "ERROR - GetModeData failed on port 0x%08x, Status: %r\r\n",
                      pNewPort,
                      Status ));
          }
        }
        else {
          //
          //  The listen failed on this port
          //
          DEBUG (( DEBUG_LISTEN | DEBUG_INFO,
                    "ERROR - Listen failed on port 0x%08x, Status: %r\r\n",
                    pPort,
                    Status ));

          //
          //  Close the listening port
          //
          EslSocketPortCloseStart ( pPort, TRUE, DEBUG_LISTEN );
        }
      }

      //
      //  Done with the socket if necessary
      //
      if ( EFI_ERROR ( Status )) {
        TempStatus = EslSocketCloseStart ( &pNewSocket->SocketProtocol,
                                           TRUE,
                                           &pSocket->errno );
        ASSERT ( EFI_SUCCESS == TempStatus );
      }
    }
  }
  else {
    DEBUG (( DEBUG_CONNECTION,
              "0x%08x: Socket FIFO full, connection refused\r\n",
              pSocket ));

    //
    //  The FIFO is full or the socket is in the wrong state
    //
    Status = EFI_BUFFER_TOO_SMALL;
  }

  //
  //  Close the connection if necessary
  //
  if (( EFI_ERROR ( Status ))
    && ( NULL == TcpPortHandle )) {
    //
    // TODO: Finish this code path
    //  The new connection does not fit into the connection FIFO
    //
    //  Process:
    //    Call close
    //    Release the resources
    
  }

  DBG_EXIT ( );
}


/**
  Get the local socket address.

  This routine returns the IPv4 address and TCP port number associated
  with the local socket.

  This routine is called by ::EslSocketGetLocalAddress to determine the
  network address for the SOCK_STREAM or SOCK_SEQPACKET socket.

  @param [in] pPort       Address of an ::ESL_PORT structure.

  @param [out] pSockAddr  Network address to receive the local system address

**/
VOID
EslTcp4LocalAddressGet (
  IN ESL_PORT * pPort,
  OUT struct sockaddr * pSockAddr
  )
{
  struct sockaddr_in * pLocalAddress;
  ESL_TCP4_CONTEXT * pTcp4;

  DBG_ENTER ( );

  //
  //  Return the local address
  //
  pTcp4 = &pPort->Context.Tcp4;
  pLocalAddress = (struct sockaddr_in *)pSockAddr;
  pLocalAddress->sin_family = AF_INET;
  pLocalAddress->sin_port = SwapBytes16 ( pTcp4->ConfigData.AccessPoint.StationPort );
  CopyMem ( &pLocalAddress->sin_addr,
            &pTcp4->ConfigData.AccessPoint.StationAddress.Addr[0],
            sizeof ( pLocalAddress->sin_addr ));

  DBG_EXIT ( );
}


/**
  Set the local port address.

  This routine sets the local port address.

  This support routine is called by ::EslSocketPortAllocate.

  @param [in] pPort       Address of an ESL_PORT structure
  @param [in] pSockAddr   Address of a sockaddr structure that contains the
                          connection point on the local machine.  An IPv4 address
                          of INADDR_ANY specifies that the connection is made to
                          all of the network stacks on the platform.  Specifying a
                          specific IPv4 address restricts the connection to the
                          network stack supporting that address.  Specifying zero
                          for the port causes the network layer to assign a port
                          number from the dynamic range.  Specifying a specific
                          port number causes the network layer to use that port.

  @param [in] bBindTest   TRUE = run bind testing

  @retval EFI_SUCCESS     The operation was successful

 **/
EFI_STATUS
EslTcp4LocalAddressSet (
  IN ESL_PORT * pPort,
  IN CONST struct sockaddr * pSockAddr,
  IN BOOLEAN bBindTest
  )
{
  EFI_TCP4_ACCESS_POINT * pAccessPoint;
  CONST struct sockaddr_in * pIpAddress;
  CONST UINT8 * pIpv4Address;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Validate the address
  //
  pIpAddress = (struct sockaddr_in *)pSockAddr;
  if ( INADDR_BROADCAST == pIpAddress->sin_addr.s_addr ) {
    //
    //  The local address must not be the broadcast address
    //
    Status = EFI_INVALID_PARAMETER;
    pPort->pSocket->errno = EADDRNOTAVAIL;
  }
  else {
    //
    //  Set the local address
    //
    pIpv4Address = (UINT8 *)&pIpAddress->sin_addr.s_addr;
    pAccessPoint = &pPort->Context.Tcp4.ConfigData.AccessPoint;
    pAccessPoint->StationAddress.Addr[0] = pIpv4Address[0];
    pAccessPoint->StationAddress.Addr[1] = pIpv4Address[1];
    pAccessPoint->StationAddress.Addr[2] = pIpv4Address[2];
    pAccessPoint->StationAddress.Addr[3] = pIpv4Address[3];

    //
    //  Determine if the default address is used
    //
    pAccessPoint->UseDefaultAddress = (BOOLEAN)( 0 == pIpAddress->sin_addr.s_addr );
    
    //
    //  Set the subnet mask
    //
    if ( pAccessPoint->UseDefaultAddress ) {
      pAccessPoint->SubnetMask.Addr[0] = 0;
      pAccessPoint->SubnetMask.Addr[1] = 0;
      pAccessPoint->SubnetMask.Addr[2] = 0;
      pAccessPoint->SubnetMask.Addr[3] = 0;
    }
    else {
      pAccessPoint->SubnetMask.Addr[0] = 0xff;
      pAccessPoint->SubnetMask.Addr[1] = ( 128 <= pAccessPoint->StationAddress.Addr[0]) ? 0xff : 0;
      pAccessPoint->SubnetMask.Addr[2] = ( 192 <= pAccessPoint->StationAddress.Addr[0]) ? 0xff : 0;
      pAccessPoint->SubnetMask.Addr[3] = ( 224 <= pAccessPoint->StationAddress.Addr[0]) ? 0xff : 0;
    }

    //
    //  Validate the IP address
    //
    pAccessPoint->StationPort = 0;
    Status = bBindTest ? EslSocketBindTest ( pPort, EADDRNOTAVAIL )
                       : EFI_SUCCESS;
    if ( !EFI_ERROR ( Status )) {
      //
      //  Set the port number
      //
      pAccessPoint->StationPort = SwapBytes16 ( pIpAddress->sin_port );
      pPort->pSocket->bAddressSet = TRUE;

      //
      //  Display the local address
      //
      DEBUG (( DEBUG_BIND,
                "0x%08x: Port, Local TCP4 Address: %d.%d.%d.%d:%d\r\n",
                pPort,
                pAccessPoint->StationAddress.Addr[0],
                pAccessPoint->StationAddress.Addr[1],
                pAccessPoint->StationAddress.Addr[2],
                pAccessPoint->StationAddress.Addr[3],
                pAccessPoint->StationPort ));
    }
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Free a receive packet

  This routine performs the network specific operations necessary
  to free a receive packet.

  This routine is called by ::EslSocketPortCloseTxDone to free a
  receive packet.

  @param [in] pPacket         Address of an ::ESL_PACKET structure.
  @param [in, out] pRxBytes   Address of the count of RX bytes

**/
VOID
EslTcp4PacketFree (
  IN ESL_PACKET * pPacket,
  IN OUT size_t * pRxBytes
  )
{
  DBG_ENTER ( );

  //
  //  Account for the receive bytes
  //
  *pRxBytes -= pPacket->Op.Tcp4Rx.RxData.DataLength;
  DBG_EXIT ( );
}


/**
  Initialize the network specific portions of an ::ESL_PORT structure.

  This routine initializes the network specific portions of an
  ::ESL_PORT structure for use by the socket.

  This support routine is called by ::EslSocketPortAllocate
  to connect the socket with the underlying network adapter
  running the TCPv4 protocol.

  @param [in] pPort       Address of an ESL_PORT structure
  @param [in] DebugFlags  Flags for debug messages

  @retval EFI_SUCCESS - Socket successfully created

 **/
EFI_STATUS
EslTcp4PortAllocate (
  IN ESL_PORT * pPort,
  IN UINTN DebugFlags
  )
{
  EFI_TCP4_ACCESS_POINT * pAccessPoint;
  ESL_SOCKET * pSocket;
  ESL_TCP4_CONTEXT * pTcp4;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Use for/break instead of goto
  for ( ; ; ) {
    //
    //  Allocate the close event
    //
    pSocket = pPort->pSocket;
    pTcp4 = &pPort->Context.Tcp4;
    Status = gBS->CreateEvent (  EVT_NOTIFY_SIGNAL,
                                 TPL_SOCKETS,
                                 (EFI_EVENT_NOTIFY)EslSocketPortCloseComplete,
                                 pPort,
                                 &pTcp4->CloseToken.CompletionToken.Event);
    if ( EFI_ERROR ( Status )) {
      DEBUG (( DEBUG_ERROR | DebugFlags,
                "ERROR - Failed to create the close event, Status: %r\r\n",
                Status ));
      pSocket->errno = ENOMEM;
      break;
    }
    DEBUG (( DEBUG_CLOSE | DEBUG_POOL,
              "0x%08x: Created close event\r\n",
              pTcp4->CloseToken.CompletionToken.Event ));

    //
    //  Allocate the connection event
    //
    Status = gBS->CreateEvent (  EVT_NOTIFY_SIGNAL,
                                 TPL_SOCKETS,
                                 (EFI_EVENT_NOTIFY)EslTcp4ConnectComplete,
                                 pPort,
                                 &pTcp4->ConnectToken.CompletionToken.Event);
    if ( EFI_ERROR ( Status )) {
      DEBUG (( DEBUG_ERROR | DebugFlags,
                "ERROR - Failed to create the connect event, Status: %r\r\n",
                Status ));
      pSocket->errno = ENOMEM;
      break;
    }
    DEBUG (( DEBUG_CLOSE | DEBUG_POOL,
              "0x%08x: Created connect event\r\n",
              pTcp4->ConnectToken.CompletionToken.Event ));

    //
    //  Initialize the port
    //
    pSocket->TxPacketOffset = OFFSET_OF ( ESL_PACKET, Op.Tcp4Tx.TxData );
    pSocket->TxTokenEventOffset = OFFSET_OF ( ESL_IO_MGMT, Token.Tcp4Tx.CompletionToken.Event );
    pSocket->TxTokenOffset = OFFSET_OF ( EFI_TCP4_IO_TOKEN, Packet.TxData );

    //
    //  Save the cancel, receive and transmit addresses
    //  pPort->pfnRxCancel = NULL; since the UEFI implementation returns EFI_UNSUPPORTED
    //
    pPort->pfnConfigure = (PFN_NET_CONFIGURE)pPort->pProtocol.TCPv4->Configure;
    pPort->pfnRxPoll = (PFN_NET_POLL)pPort->pProtocol.TCPv4->Poll;
    pPort->pfnRxStart = (PFN_NET_IO_START)pPort->pProtocol.TCPv4->Receive;
    pPort->pfnTxStart = (PFN_NET_IO_START)pPort->pProtocol.TCPv4->Transmit;

    //
    //  Set the configuration flags
    //
    pAccessPoint = &pPort->Context.Tcp4.ConfigData.AccessPoint;
    pAccessPoint->ActiveFlag = FALSE;
    pTcp4->ConfigData.TimeToLive = 255;
    break;
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Close a TCP4 port.

  This routine releases the network specific resources allocated by
  ::EslTcp4PortAllocate.

  This routine is called by ::EslSocketPortClose.
  See the \ref PortCloseStateMachine section.
  
  @param [in] pPort       Address of an ::ESL_PORT structure.

  @retval EFI_SUCCESS     The port is closed
  @retval other           Port close error

**/
EFI_STATUS
EslTcp4PortClose (
  IN ESL_PORT * pPort
  )
{
  UINTN DebugFlags;
  ESL_TCP4_CONTEXT * pTcp4;
  EFI_STATUS Status;
  
  DBG_ENTER ( );

  //
  //  Locate the port in the socket list
  //
  Status = EFI_SUCCESS;
  DebugFlags = pPort->DebugFlags;
  pTcp4 = &pPort->Context.Tcp4;

  //
  //  Done with the connect event
  //
  if ( NULL != pTcp4->ConnectToken.CompletionToken.Event ) {
    Status = gBS->CloseEvent ( pTcp4->ConnectToken.CompletionToken.Event );
    if ( !EFI_ERROR ( Status )) {
      DEBUG (( DebugFlags | DEBUG_POOL,
                "0x%08x: Closed connect event\r\n",
                pTcp4->ConnectToken.CompletionToken.Event ));
    }
    else {
      DEBUG (( DEBUG_ERROR | DebugFlags,
                "ERROR - Failed to close the connect event, Status: %r\r\n",
                Status ));
      ASSERT ( EFI_SUCCESS == Status );
    }
  }

  //
  //  Done with the close event
  //
  if ( NULL != pTcp4->CloseToken.CompletionToken.Event ) {
    Status = gBS->CloseEvent ( pTcp4->CloseToken.CompletionToken.Event );
    if ( !EFI_ERROR ( Status )) {
      DEBUG (( DebugFlags | DEBUG_POOL,
                "0x%08x: Closed close event\r\n",
                pTcp4->CloseToken.CompletionToken.Event ));
    }
    else {
      DEBUG (( DEBUG_ERROR | DebugFlags,
                "ERROR - Failed to close the close event, Status: %r\r\n",
                Status ));
      ASSERT ( EFI_SUCCESS == Status );
    }
  }

  //
  //  Done with the listen completion event
  //
  if ( NULL != pTcp4->ListenToken.CompletionToken.Event ) {
    Status = gBS->CloseEvent ( pTcp4->ListenToken.CompletionToken.Event );
    if ( !EFI_ERROR ( Status )) {
      DEBUG (( DebugFlags | DEBUG_POOL,
                "0x%08x: Closed listen completion event\r\n",
                pTcp4->ListenToken.CompletionToken.Event ));
    }
    else {
      DEBUG (( DEBUG_ERROR | DebugFlags,
                "ERROR - Failed to close the listen completion event, Status: %r\r\n",
                Status ));
      ASSERT ( EFI_SUCCESS == Status );
    }
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Perform the network specific close operation on the port.

  This routine performs a cancel operations on the TCPv4 port to
  shutdown the receive operations on the port.

  This routine is called by the ::EslSocketPortCloseTxDone
  routine after the port completes all of the transmission.

  @param [in] pPort           Address of an ::ESL_PORT structure.

  @retval EFI_SUCCESS         The port is closed, not normally returned
  @retval EFI_NOT_READY       The port is still closing
  @retval EFI_ALREADY_STARTED Error, the port is in the wrong state,
                              most likely the routine was called already.

**/
EFI_STATUS
EslTcp4PortCloseOp (
  IN ESL_PORT * pPort
  )
{
  ESL_TCP4_CONTEXT * pTcp4;
  EFI_TCP4_PROTOCOL * pTcp4Protocol;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Close the configured port
  //
  Status = EFI_SUCCESS;
  pTcp4 = &pPort->Context.Tcp4;
  pTcp4Protocol = pPort->pProtocol.TCPv4;
  pTcp4->CloseToken.AbortOnClose = pPort->bCloseNow;
  Status = pTcp4Protocol->Close ( pTcp4Protocol,
                                  &pTcp4->CloseToken );
  if ( !EFI_ERROR ( Status )) {
    DEBUG (( pPort->DebugFlags | DEBUG_CLOSE | DEBUG_INFO,
              "0x%08x: Port close started\r\n",
              pPort ));
  }
  else {
    DEBUG (( DEBUG_ERROR | pPort->DebugFlags | DEBUG_CLOSE | DEBUG_INFO,
             "ERROR - Close failed on port 0x%08x, Status: %r\r\n",
             pPort,
             Status ));
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Receive data from a network connection.

  This routine attempts to return buffered data to the caller.  The
  data is removed from the urgent queue if the message flag MSG_OOB
  is specified, otherwise data is removed from the normal queue.
  See the \ref ReceiveEngine section.

  This routine is called by ::EslSocketReceive to handle the network
  specific receive operation to support SOCK_STREAM and SOCK_SEQPACKET
  sockets.

  @param [in] pPort           Address of an ::ESL_PORT structure.

  @param [in] pPacket         Address of an ::ESL_PACKET structure.
  
  @param [in] pbConsumePacket Address of a BOOLEAN indicating if the packet is to be consumed
  
  @param [in] BufferLength    Length of the the buffer
  
  @param [in] pBuffer         Address of a buffer to receive the data.
  
  @param [in] pDataLength     Number of received data bytes in the buffer.

  @param [out] pAddress       Network address to receive the remote system address

  @param [out] pSkipBytes     Address to receive the number of bytes skipped

  @return   Returns the address of the next free byte in the buffer.

 **/
UINT8 *
EslTcp4Receive (
  IN ESL_PORT * pPort,
  IN ESL_PACKET * pPacket,
  IN BOOLEAN * pbConsumePacket,
  IN size_t BufferLength,
  IN UINT8 * pBuffer,
  OUT size_t * pDataLength,
  OUT struct sockaddr * pAddress,
  OUT size_t * pSkipBytes
  )
{
  size_t DataLength;
  struct sockaddr_in * pRemoteAddress;
  ESL_TCP4_CONTEXT * pTcp4;

  DBG_ENTER ( );

  //
  //  Return the remote system address if requested
  //
  if ( NULL != pAddress ) {
    //
    //  Build the remote address
    //
    pTcp4 = &pPort->Context.Tcp4;
    DEBUG (( DEBUG_RX,
              "Getting packet remote address: %d.%d.%d.%d:%d\r\n",
              pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[0],
              pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[1],
              pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[2],
              pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[3],
              pTcp4->ConfigData.AccessPoint.RemotePort ));
    pRemoteAddress = (struct sockaddr_in *)pAddress;
    CopyMem ( &pRemoteAddress->sin_addr,
              &pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[0],
              sizeof ( pRemoteAddress->sin_addr ));
    pRemoteAddress->sin_port = SwapBytes16 ( pTcp4->ConfigData.AccessPoint.RemotePort );
  }

  //
  //  Determine the amount of received data
  //
  DataLength = pPacket->ValidBytes;
  if ( BufferLength < DataLength ) {
    DataLength = BufferLength;
  }

  //
  //  Move the data into the buffer
  //
  DEBUG (( DEBUG_RX,
            "0x%08x: Port copy packet 0x%08x data into 0x%08x, 0x%08x bytes\r\n",
            pPort,
            pPacket,
            pBuffer,
            DataLength ));
  CopyMem ( pBuffer, pPacket->pBuffer, DataLength );

  //
  //  Set the next buffer address
  //
  pBuffer += DataLength;

  //
  //  Determine if the data is being read
  //
  if ( *pbConsumePacket ) {
    //
    //  Account for the bytes consumed
    //
    pPacket->pBuffer += DataLength;
    pPacket->ValidBytes -= DataLength;
    DEBUG (( DEBUG_RX,
              "0x%08x: Port account for 0x%08x bytes\r\n",
              pPort,
              DataLength ));

    //
    //  Determine if the entire packet was consumed
    //
    if (( 0 == pPacket->ValidBytes )
      || ( SOCK_STREAM != pPort->pSocket->Type )) {
      //
      //  All done with this packet
      //  Account for any discarded data
      //
      *pSkipBytes = pPacket->ValidBytes;
    }
    else
    {
      //
      //  More data to consume later
      //
      *pbConsumePacket = FALSE;
    }
  }

  //
  //  Return the data length and the buffer address
  //
  *pDataLength = DataLength;
  DBG_EXIT_HEX ( pBuffer );
  return pBuffer;
}


/**
  Get the remote socket address.

  This routine returns the address of the remote connection point
  associated with the SOCK_STREAM or SOCK_SEQPACKET socket.

  This routine is called by ::EslSocketGetPeerAddress to detemine
  the TCPv4 address and por number associated with the network adapter.

  @param [in] pPort       Address of an ::ESL_PORT structure.

  @param [out] pAddress   Network address to receive the remote system address

**/
VOID
EslTcp4RemoteAddressGet (
  IN ESL_PORT * pPort,
  OUT struct sockaddr * pAddress
  )
{
  struct sockaddr_in * pRemoteAddress;
  ESL_TCP4_CONTEXT * pTcp4;

  DBG_ENTER ( );

  //
  //  Return the remote address
  //
  pTcp4 = &pPort->Context.Tcp4;
  pRemoteAddress = (struct sockaddr_in *)pAddress;
  pRemoteAddress->sin_family = AF_INET;
  pRemoteAddress->sin_port = SwapBytes16 ( pTcp4->ConfigData.AccessPoint.RemotePort );
  CopyMem ( &pRemoteAddress->sin_addr,
            &pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[0],
            sizeof ( pRemoteAddress->sin_addr ));

  DBG_EXIT ( );
}


/**
  Set the remote address

  This routine sets the remote address in the port.

  This routine is called by ::EslSocketConnect to specify the
  remote network address.

  @param [in] pPort           Address of an ::ESL_PORT structure.

  @param [in] pSockAddr       Network address of the remote system.

  @param [in] SockAddrLength  Length in bytes of the network address.

  @retval EFI_SUCCESS     The operation was successful

 **/
EFI_STATUS
EslTcp4RemoteAddressSet (
  IN ESL_PORT * pPort,
  IN CONST struct sockaddr * pSockAddr,
  IN socklen_t SockAddrLength
  )
{
  CONST struct sockaddr_in * pRemoteAddress;
  ESL_TCP4_CONTEXT * pTcp4;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Set the remote address
  //
  pTcp4 = &pPort->Context.Tcp4;
  pRemoteAddress = (struct sockaddr_in *)pSockAddr;
  pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[0] = (UINT8)( pRemoteAddress->sin_addr.s_addr );
  pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[1] = (UINT8)( pRemoteAddress->sin_addr.s_addr >> 8 );
  pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[2] = (UINT8)( pRemoteAddress->sin_addr.s_addr >> 16 );
  pTcp4->ConfigData.AccessPoint.RemoteAddress.Addr[3] = (UINT8)( pRemoteAddress->sin_addr.s_addr >> 24 );
  pTcp4->ConfigData.AccessPoint.RemotePort = SwapBytes16 ( pRemoteAddress->sin_port );
  Status = EFI_SUCCESS;
  if ( INADDR_BROADCAST == pRemoteAddress->sin_addr.s_addr ) {
    DEBUG (( DEBUG_CONNECT,
              "ERROR - Invalid remote address\r\n" ));
    Status = EFI_INVALID_PARAMETER;
    pPort->pSocket->errno = EAFNOSUPPORT;
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Process the receive completion

  This routine queues the data in FIFO order in either the urgent
  or normal data queues depending upon the type of data received.
  See the \ref ReceiveEngine section.

  This routine is called by the TCPv4 driver when some data is
  received.

  Buffer the data that was just received.

  @param [in] Event     The receive completion event

  @param [in] pIo       Address of an ::ESL_IO_MGMT structure

**/
VOID
EslTcp4RxComplete (
  IN EFI_EVENT Event,
  IN ESL_IO_MGMT * pIo
  )
{
  BOOLEAN bUrgent;
  size_t LengthInBytes;
  ESL_PACKET * pPacket;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Get the operation status.
  //
  Status = pIo->Token.Tcp4Rx.CompletionToken.Status;

  //
  //      +--------------------+   +---------------------------+
  //      | ESL_IO_MGMT        |   | ESL_PACKET                |
  //      |                    |   |                           |
  //      |    +---------------+   +-----------------------+   |
  //      |    | Token         |   | EFI_TCP4_RECEIVE_DATA |   |
  //      |    |        RxData --> |                       |   |
  //      |    |               |   +-----------------------+---+
  //      |    |        Event  |   |       Data Buffer         |
  //      +----+---------------+   |                           |
  //                               |                           |
  //                               +---------------------------+
  //
  //
  //  Duplicate the buffer address and length for use by the
  //  buffer handling code in EslTcp4Receive.  These fields are
  //  used when a partial read is done of the data from the
  //  packet.
  //
  pPacket = pIo->pPacket;
  pPacket->pBuffer = pPacket->Op.Tcp4Rx.RxData.FragmentTable[0].FragmentBuffer;
  LengthInBytes = pPacket->Op.Tcp4Rx.RxData.DataLength;
  pPacket->ValidBytes = LengthInBytes;

  //
  //  Get the data type so that it may be linked to the
  //  correct receive buffer list on the ESL_SOCKET structure
  //
  bUrgent = pPacket->Op.Tcp4Rx.RxData.UrgentFlag;

  //
  //  Complete this request
  //
  EslSocketRxComplete ( pIo, Status, LengthInBytes, bUrgent );
  DBG_EXIT ( );
}


/**
  Start a receive operation

  This routine posts a receive buffer to the TCPv4 driver.
  See the \ref ReceiveEngine section.

  This support routine is called by EslSocketRxStart.

  @param [in] pPort       Address of an ::ESL_PORT structure.
  @param [in] pIo         Address of an ::ESL_IO_MGMT structure.

 **/
VOID
EslTcp4RxStart (
  IN ESL_PORT * pPort,
  IN ESL_IO_MGMT * pIo
  )
{
  ESL_PACKET * pPacket;

  DBG_ENTER ( );

  //
  //  Initialize the buffer for receive
  //
  pPacket = pIo->pPacket;
  pIo->Token.Tcp4Rx.Packet.RxData = &pPacket->Op.Tcp4Rx.RxData;
  pPacket->Op.Tcp4Rx.RxData.DataLength = sizeof ( pPacket->Op.Tcp4Rx.Buffer );
  pPacket->Op.Tcp4Rx.RxData.FragmentCount = 1;
  pPacket->Op.Tcp4Rx.RxData.FragmentTable[0].FragmentLength = pPacket->Op.Tcp4Rx.RxData.DataLength;
  pPacket->Op.Tcp4Rx.RxData.FragmentTable[0].FragmentBuffer = &pPacket->Op.Tcp4Rx.Buffer[0];

  DBG_EXIT ( );
}


/**
  Determine if the socket is configured.

  This routine uses the flag ESL_SOCKET::bConfigured to determine
  if the network layer's configuration routine has been called.

  This routine is called by EslSocketIsConfigured to verify
  that the socket has been configured.

  @param [in] pSocket   Address of an ::ESL_SOCKET structure.

  @retval EFI_SUCCESS - The port is connected
  @retval EFI_NOT_STARTED - The port is not connected

 **/
 EFI_STATUS
 EslTcp4SocketIsConfigured (
  IN ESL_SOCKET * pSocket
  )
{
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Determine the socket configuration status
  //
  Status = pSocket->bConfigured ? EFI_SUCCESS : EFI_NOT_STARTED;

  //
  //  Return the port connected state.
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Buffer data for transmission over a network connection.

  This routine buffers data for the transmit engine in one of two
  queues, one for urgent (out-of-band) data and the other for normal
  data.  The urgent data is provided to TCP as soon as it is available,
  allowing the TCP layer to schedule transmission of the urgent data
  between packets of normal data.

  This routine is called by ::EslSocketTransmit to buffer
  data for transmission.  When the \ref TransmitEngine has resources,
  this routine will start the transmission of the next buffer on
  the network connection.

  Transmission errors are returned during the next transmission or
  during the close operation.  Only buffering errors are returned
  during the current transmission attempt.

  @param [in] pSocket         Address of an ::ESL_SOCKET structure
  
  @param [in] Flags           Message control flags
  
  @param [in] BufferLength    Length of the the buffer
  
  @param [in] pBuffer         Address of a buffer to receive the data.
  
  @param [in] pDataLength     Number of received data bytes in the buffer.

  @param [in] pAddress        Network address of the remote system address

  @param [in] AddressLength   Length of the remote network address structure

  @retval EFI_SUCCESS - Socket data successfully buffered

 **/
EFI_STATUS
EslTcp4TxBuffer (
  IN ESL_SOCKET * pSocket,
  IN int Flags,
  IN size_t BufferLength,
  IN CONST UINT8 * pBuffer,
  OUT size_t * pDataLength,
  IN const struct sockaddr * pAddress,
  IN socklen_t AddressLength
  )
{
  BOOLEAN bUrgent;
  BOOLEAN bUrgentQueue;
  ESL_PACKET * pPacket;
  ESL_IO_MGMT ** ppActive;
  ESL_IO_MGMT ** ppFree;
  ESL_PORT * pPort;
  ESL_PACKET ** ppQueueHead;
  ESL_PACKET ** ppQueueTail;
  ESL_PACKET * pPreviousPacket;
  ESL_TCP4_CONTEXT * pTcp4;
  size_t * pTxBytes;
  EFI_TCP4_TRANSMIT_DATA * pTxData;
  EFI_STATUS Status;
  EFI_TPL TplPrevious;

  DBG_ENTER ( );

  //
  //  Assume failure
  //
  Status = EFI_UNSUPPORTED;
  pSocket->errno = ENOTCONN;
  *pDataLength = 0;

  //
  //  Verify that the socket is connected
  //
  if ( SOCKET_STATE_CONNECTED == pSocket->State ) {
    //
    //  Locate the port
    //
    pPort = pSocket->pPortList;
    if ( NULL != pPort ) {
      //
      //  Determine the queue head
      //
      pTcp4 = &pPort->Context.Tcp4;
      bUrgent = (BOOLEAN)( 0 != ( Flags & MSG_OOB ));
      bUrgentQueue = bUrgent
                    && ( !pSocket->bOobInLine )
                    && pSocket->pApi->bOobSupported;
      if ( bUrgentQueue ) {
        ppQueueHead = &pSocket->pTxOobPacketListHead;
        ppQueueTail = &pSocket->pTxOobPacketListTail;
        ppActive = &pPort->pTxOobActive;
        ppFree = &pPort->pTxOobFree;
        pTxBytes = &pSocket->TxOobBytes;
      }
      else {
        ppQueueHead = &pSocket->pTxPacketListHead;
        ppQueueTail = &pSocket->pTxPacketListTail;
        ppActive = &pPort->pTxActive;
        ppFree = &pPort->pTxFree;
        pTxBytes = &pSocket->TxBytes;
      }

      //
      //  Verify that there is enough room to buffer another
      //  transmit operation
      //
      if ( pSocket->MaxTxBuf > *pTxBytes ) {
        if ( pPort->bTxFlowControl ) {
          DEBUG (( DEBUG_TX,
                    "TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT\r\n0x%08x: pPort, TX flow control released, Max bytes: %d > %d bufferred bytes\r\n",
                    pPort,
                    pSocket->MaxTxBuf,
                    *pTxBytes ));
          pPort->bTxFlowControl = FALSE;
        }

        //
        //  Attempt to allocate the packet
        //
        Status = EslSocketPacketAllocate ( &pPacket,
                                           sizeof ( pPacket->Op.Tcp4Tx )
                                           - sizeof ( pPacket->Op.Tcp4Tx.Buffer )
                                           + BufferLength,
                                           0,
                                           DEBUG_TX );
        if ( !EFI_ERROR ( Status )) {
          //
          //  Initialize the transmit operation
          //
          pTxData = &pPacket->Op.Tcp4Tx.TxData;
          pTxData->Push = TRUE || bUrgent;
          pTxData->Urgent = bUrgent;
          pTxData->DataLength = (UINT32) BufferLength;
          pTxData->FragmentCount = 1;
          pTxData->FragmentTable[0].FragmentLength = (UINT32) BufferLength;
          pTxData->FragmentTable[0].FragmentBuffer = &pPacket->Op.Tcp4Tx.Buffer[0];

          //
          //  Copy the data into the buffer
          //
          CopyMem ( &pPacket->Op.Tcp4Tx.Buffer[0],
                    pBuffer,
                    BufferLength );

          //
          //  Synchronize with the socket layer
          //
          RAISE_TPL ( TplPrevious, TPL_SOCKETS );

          //
          //  Stop transmission after an error
          //
          if ( !EFI_ERROR ( pSocket->TxError )) {
            //
            //  Display the request
            //
            DEBUG (( DEBUG_TX,
                      "Send %d %s bytes from 0x%08x\r\n",
                      BufferLength,
                      bUrgent ? L"urgent" : L"normal",
                      pBuffer ));

            //
            //  Queue the data for transmission
            //
            pPacket->pNext = NULL;
            pPreviousPacket = *ppQueueTail;
            if ( NULL == pPreviousPacket ) {
              *ppQueueHead = pPacket;
            }
            else {
              pPreviousPacket->pNext = pPacket;
            }
            *ppQueueTail = pPacket;
            DEBUG (( DEBUG_TX,
                      "0x%08x: Packet on %s transmit list\r\n",
                      pPacket,
                      bUrgentQueue ? L"urgent" : L"normal" ));

            //
            //  Account for the buffered data
            //
            *pTxBytes += BufferLength;
            *pDataLength = BufferLength;

            //
            //  Start the transmit engine if it is idle
            //
            if ( NULL != *ppFree ) {
              EslSocketTxStart ( pPort,
                                 ppQueueHead,
                                 ppQueueTail,
                                 ppActive,
                                 ppFree );
            }
          }
          else {
            //
            //  Previous transmit error
            //  Stop transmission
            //
            Status = pSocket->TxError;
            pSocket->errno = EIO;

            //
            //  Free the packet
            //
            EslSocketPacketFree ( pPacket, DEBUG_TX );
          }

          //
          //  Release the socket layer synchronization
          //
          RESTORE_TPL ( TplPrevious );
        }
        else {
          //
          //  Packet allocation failed
          //
          pSocket->errno = ENOMEM;
        }
      }
      else {
        if ( !pPort->bTxFlowControl ) {
          DEBUG (( DEBUG_TX,
                    "0x%08x: pPort, TX flow control applied, Max bytes %d <= %d bufferred bytes\r\nTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT\r\n",
                    pPort,
                    pSocket->MaxTxBuf,
                    *pTxBytes ));
          pPort->bTxFlowControl = TRUE;
        }
        //
        //  Not enough buffer space available
        //
        pSocket->errno = EAGAIN;
        Status = EFI_NOT_READY;
      }
    }
  }

  //
  //  Return the operation status
  //
  DBG_EXIT_STATUS ( Status );
  return Status;
}


/**
  Process the normal data transmit completion

  This routine use ::EslSocketTxComplete to perform the transmit
  completion processing for normal data.

  This routine is called by the TCPv4 network layer when a
  normal data transmit request completes.

  @param [in] Event     The normal transmit completion event

  @param [in] pIo       The ESL_IO_MGMT structure address

**/
VOID
EslTcp4TxComplete (
  IN EFI_EVENT Event,
  IN ESL_IO_MGMT * pIo
  )
{
  UINT32 LengthInBytes;
  ESL_PACKET * pPacket;
  ESL_PORT * pPort;
  ESL_SOCKET * pSocket;
  EFI_STATUS Status;
  
  DBG_ENTER ( );

  //
  //  Locate the active transmit packet
  //
  pPacket = pIo->pPacket;
  pPort = pIo->pPort;
  pSocket = pPort->pSocket;

  //
  //  Get the transmit length and status
  //
  LengthInBytes = pPacket->Op.Tcp4Tx.TxData.DataLength;
  pSocket->TxBytes -= LengthInBytes;
  Status = pIo->Token.Tcp4Tx.CompletionToken.Status;

  //
  //  Complete the transmit operation
  //
  EslSocketTxComplete ( pIo,
                        LengthInBytes,
                        Status,
                        "Normal ",
                        &pSocket->pTxPacketListHead,
                        &pSocket->pTxPacketListTail,
                        &pPort->pTxActive,
                        &pPort->pTxFree );
  DBG_EXIT ( );
}


/**
  Process the urgent data transmit completion

  This routine use ::EslSocketTxComplete to perform the transmit
  completion processing for urgent data.

  This routine is called by the TCPv4 network layer when a
  urgent data transmit request completes.

  @param [in] Event     The urgent transmit completion event

  @param [in] pIo       The ESL_IO_MGMT structure address

**/
VOID
EslTcp4TxOobComplete (
  IN EFI_EVENT Event,
  IN ESL_IO_MGMT * pIo
  )
{
  UINT32 LengthInBytes;
  ESL_PACKET * pPacket;
  ESL_PORT * pPort;
  ESL_SOCKET * pSocket;
  EFI_STATUS Status;

  DBG_ENTER ( );

  //
  //  Locate the active transmit packet
  //
  pPacket = pIo->pPacket;
  pPort = pIo->pPort;
  pSocket = pPort->pSocket;

  //
  //  Get the transmit length and status
  //
  LengthInBytes = pPacket->Op.Tcp4Tx.TxData.DataLength;
  pSocket->TxOobBytes -= LengthInBytes;
  Status = pIo->Token.Tcp4Tx.CompletionToken.Status;

  //
  //  Complete the transmit operation
  //
  EslSocketTxComplete ( pIo,
                        LengthInBytes,
                        Status,
                        "Urgent ",
                        &pSocket->pTxOobPacketListHead,
                        &pSocket->pTxOobPacketListTail,
                        &pPort->pTxOobActive,
                        &pPort->pTxOobFree );
  DBG_EXIT ( );
}


/**
  Interface between the socket layer and the network specific
  code that supports SOCK_STREAM and SOCK_SEQPACKET sockets
  over TCPv4.
**/
CONST ESL_PROTOCOL_API cEslTcp4Api = {
  "TCPv4",
  IPPROTO_TCP,
  OFFSET_OF ( ESL_PORT, Context.Tcp4.ConfigData ),
  OFFSET_OF ( ESL_LAYER, pTcp4List ),
  OFFSET_OF ( struct sockaddr_in, sin_zero ),
  sizeof ( struct sockaddr_in ),
  AF_INET,
  sizeof (((ESL_PACKET *)0 )->Op.Tcp4Rx ),
  OFFSET_OF ( ESL_PACKET, Op.Tcp4Rx.Buffer ) - OFFSET_OF ( ESL_PACKET, Op ),
  OFFSET_OF ( ESL_IO_MGMT, Token.Tcp4Rx.Packet.RxData ),
  TRUE,
  EADDRINUSE,
  EslTcp4Accept,
  EslTcp4ConnectPoll,
  EslTcp4ConnectStart,
  EslTcp4SocketIsConfigured,
  EslTcp4LocalAddressGet,
  EslTcp4LocalAddressSet,
  EslTcp4Listen,
  NULL,   //  OptionGet
  NULL,   //  OptionSet
  EslTcp4PacketFree,
  EslTcp4PortAllocate,
  EslTcp4PortClose,
  EslTcp4PortCloseOp,
  FALSE,
  EslTcp4Receive,
  EslTcp4RemoteAddressGet,
  EslTcp4RemoteAddressSet,
  EslTcp4RxComplete,
  EslTcp4RxStart,
  EslTcp4TxBuffer,
  EslTcp4TxComplete,
  EslTcp4TxOobComplete
};