path: root/MdeModulePkg/Universal/Network/MnpDxe/MnpIo.c

/** @file

Copyright (c) 2005 - 2007, 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.

Module Name:

  MnpIo.c

Abstract:

  Implementation of Managed Network Protocol I/O functions.


**/

#include <Library/NetLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/BaseLib.h>
#include <Library/MemoryAllocationLib.h>
#include "MnpImpl.h"


/**
  Validates the Mnp transmit token.

  @param  Instance              Pointer to the Mnp instance context data.
  @param  Token                 Pointer to the transmit token to check.

  @return The Token is valid or not.

**/
BOOLEAN
MnpIsValidTxToken (
  IN MNP_INSTANCE_DATA                     *Instance,
  IN EFI_MANAGED_NETWORK_COMPLETION_TOKEN  *Token
  )
{
  MNP_SERVICE_DATA                  *MnpServiceData;
  EFI_MANAGED_NETWORK_TRANSMIT_DATA *TxData;
  UINT32                            Index;
  UINT32                            TotalLength;
  EFI_MANAGED_NETWORK_FRAGMENT_DATA *FragmentTable;

  MnpServiceData = Instance->MnpServiceData;
  NET_CHECK_SIGNATURE (MnpServiceData, MNP_SERVICE_DATA_SIGNATURE);

  TxData  = Token->Packet.TxData;

  if ((Token->Event == NULL) || (TxData == NULL) || (TxData->FragmentCount == 0)) {
    //
    // The token is invalid if the Event is NULL, or the TxData is NULL, or
    // the fragment count is zero.
    //
    DEBUG ((EFI_D_WARN, "MnpIsValidTxToken: Invalid Token.\n"));
    return FALSE;
  }

  if ((TxData->DestinationAddress != NULL) && (TxData->HeaderLength != 0)) {
    //
    // The token is invalid if the HeaderLength isn't zero while the DestinationAddress
    // is NULL (The destination address is already put into the packet).
    //
    DEBUG ((EFI_D_WARN, "MnpIsValidTxToken: DestinationAddress isn't NULL, HeaderLength must be 0.\n"));
    return FALSE;
  }

  TotalLength   = 0;
  FragmentTable = TxData->FragmentTable;
  for (Index = 0; Index < TxData->FragmentCount; Index++) {

    if ((FragmentTable[Index].FragmentLength == 0) || (FragmentTable[Index].FragmentBuffer == NULL)) {
      //
      // The token is invalid if any FragmentLength is zero or any FragmentBuffer is NULL.
      //
      DEBUG ((EFI_D_WARN, "MnpIsValidTxToken: Invalid FragmentLength or FragmentBuffer.\n"));
      return FALSE;
    }

    TotalLength += FragmentTable[Index].FragmentLength;
  }

  if ((TxData->DestinationAddress == NULL) && (FragmentTable[0].FragmentLength < TxData->HeaderLength)) {
    //
    // Media header is split between fragments.
    //
    return FALSE;
  }

  if (TotalLength != (TxData->DataLength + TxData->HeaderLength)) {
    //
    // The length calculated from the fragment information doesn't equal to the
    // sum of the DataLength and the HeaderLength.
    //
    DEBUG ((EFI_D_WARN, "MnpIsValidTxData: Invalid Datalength compared with the sum of fragment length.\n"));
    return FALSE;
  }

  if (TxData->DataLength > MnpServiceData->Mtu) {
    //
    // The total length is larger than the MTU.
    //
    DEBUG ((EFI_D_WARN, "MnpIsValidTxData: TxData->DataLength exceeds Mtu.\n"));
    return FALSE;
  }

  return TRUE;
}


/**
  Build the packet to transmit from the TxData passed in.

  @param  MnpServiceData        Pointer to the mnp service context data.
  @param  TxData                Pointer to the transmit data containing the
                                information to build the packet.
  @param  PktBuf                Pointer to record the address of the packet.
  @param  PktLen                Pointer to a UINT32 variable used to record the
                                packet's length.

  @return None.

**/
VOID
MnpBuildTxPacket (
  IN  MNP_SERVICE_DATA                   *MnpServiceData,
  IN  EFI_MANAGED_NETWORK_TRANSMIT_DATA  *TxData,
  OUT UINT8                              **PktBuf,
  OUT UINT32                             *PktLen
  )
{
  EFI_SIMPLE_NETWORK_MODE *SnpMode;
  UINT8                   *DstPos;
  UINT16                  Index;

  if ((TxData->DestinationAddress == NULL) && (TxData->FragmentCount == 1)) {
    //
    // Media header is in FragmentTable and there is only one fragment,
    // use fragment buffer directly.
    //
    *PktBuf = TxData->FragmentTable[0].FragmentBuffer;
    *PktLen = TxData->FragmentTable[0].FragmentLength;
  } else {
    //
    // Either media header isn't in FragmentTable or there is more than
    // one fragment, copy the data into the packet buffer. Reserve the
    // media header space if necessary.
    //
    SnpMode = MnpServiceData->Snp->Mode;
    DstPos  = MnpServiceData->TxBuf;

    *PktLen = 0;
    if (TxData->DestinationAddress != NULL) {
      //
      // If dest address is not NULL, move DstPos to reserve space for the
      // media header. Add the media header length to buflen.
      //
      DstPos += SnpMode->MediaHeaderSize;
      *PktLen += SnpMode->MediaHeaderSize;
    }

    for (Index = 0; Index < TxData->FragmentCount; Index++) {
      //
      // Copy the data.
      //
      CopyMem (
        DstPos,
        TxData->FragmentTable[Index].FragmentBuffer,
        TxData->FragmentTable[Index].FragmentLength
        );
      DstPos += TxData->FragmentTable[Index].FragmentLength;
    }

    //
    // Set the buffer pointer and the buffer length.
    //
    *PktBuf = MnpServiceData->TxBuf;
    *PktLen += TxData->DataLength + TxData->HeaderLength;
  }
}


/**
  Synchronously send out the packet.

  @param  MnpServiceData        Pointer to the mnp service context data.
  @param  Packet                Pointer to the pakcet buffer.
  @param  Length                The length of the packet.
  @param  Token                 Pointer to the token the packet generated from.

  @retval EFI_SUCCESS           The packet is sent out.
  @retval EFI_TIMEOUT           Time out occurs, the packet isn't sent.
  @retval EFI_DEVICE_ERROR      An unexpected network error occurs.

**/
EFI_STATUS
MnpSyncSendPacket (
  IN MNP_SERVICE_DATA                      *MnpServiceData,
  IN UINT8                                 *Packet,
  IN UINT32                                Length,
  IN EFI_MANAGED_NETWORK_COMPLETION_TOKEN  *Token
  )
{
  EFI_STATUS                        Status;
  EFI_SIMPLE_NETWORK_PROTOCOL       *Snp;
  EFI_MANAGED_NETWORK_TRANSMIT_DATA *TxData;
  UINT32                            HeaderSize;
  UINT8                             *TxBuf;

  Snp         = MnpServiceData->Snp;
  TxData      = Token->Packet.TxData;

  HeaderSize  = Snp->Mode->MediaHeaderSize - TxData->HeaderLength;

  //
  // Start the timeout event.
  //
  Status = gBS->SetTimer (
                  MnpServiceData->TxTimeoutEvent,
                  TimerRelative,
                  MNP_TX_TIMEOUT_TIME
                  );
  if (EFI_ERROR (Status)) {

    goto SIGNAL_TOKEN;
  }

  for (;;) {
    //
    // Transmit the packet through SNP.
    //
    Status = Snp->Transmit (
                    Snp,
                    HeaderSize,
                    Length,
                    Packet,
                    TxData->SourceAddress,
                    TxData->DestinationAddress,
                    &TxData->ProtocolType
                    );
    if ((Status != EFI_SUCCESS) && (Status != EFI_NOT_READY)) {

      Status = EFI_DEVICE_ERROR;
      break;
    }

    //
    // If Status is EFI_SUCCESS, the packet is put in the transmit queue.
    // if Status is EFI_NOT_READY, the transmit engine of the network interface is busy.
    // Both need to sync SNP.
    //
    TxBuf = NULL;
    do {
      //
      // Get the recycled transmit buffer status.
      //
      Snp->GetStatus (Snp, NULL, (VOID **) &TxBuf);

      if (!EFI_ERROR (gBS->CheckEvent (MnpServiceData->TxTimeoutEvent))) {

        Status = EFI_TIMEOUT;
        break;
      }
    } while (TxBuf == NULL);

    if ((Status == EFI_SUCCESS) || (Status == EFI_TIMEOUT)) {

      break;
    } else {
      //
      // Status is EFI_NOT_READY. Restart the timer event and call Snp->Transmit again.
      //
      gBS->SetTimer (
            MnpServiceData->TxTimeoutEvent,
            TimerRelative,
            MNP_TX_TIMEOUT_TIME
            );
    }
  }

  //
  // Cancel the timer event.
  //
  gBS->SetTimer (MnpServiceData->TxTimeoutEvent, TimerCancel, 0);

SIGNAL_TOKEN:

  Token->Status = Status;
  gBS->SignalEvent (Token->Event);

  //
  // Dispatch the DPC queued by the NotifyFunction of Token->Event.
  //
  NetLibDispatchDpc ();

  return EFI_SUCCESS;
}


/**
  Try to deliver the received packet to the instance.

  @param  Instance              Pointer to the mnp instance context data.

  @retval EFI_SUCCESS           The received packet is delivered, or there is no
                                packet to deliver, or there is no available receive
                                token.
  @retval EFI_OUT_OF_RESOURCES  The deliver fails due to lack of memory resource.

**/
EFI_STATUS
MnpInstanceDeliverPacket (
  IN MNP_INSTANCE_DATA  *Instance
  )
{
  MNP_SERVICE_DATA                      *MnpServiceData;
  MNP_RXDATA_WRAP                       *RxDataWrap;
  NET_BUF                               *DupNbuf;
  EFI_MANAGED_NETWORK_RECEIVE_DATA      *RxData;
  EFI_SIMPLE_NETWORK_MODE               *SnpMode;
  EFI_MANAGED_NETWORK_COMPLETION_TOKEN  *RxToken;

  MnpServiceData = Instance->MnpServiceData;
  NET_CHECK_SIGNATURE (MnpServiceData, MNP_SERVICE_DATA_SIGNATURE);

  if (NetMapIsEmpty (&Instance->RxTokenMap) || IsListEmpty (&Instance->RcvdPacketQueue)) {
    //
    // No pending received data or no available receive token, return.
    //
    return EFI_SUCCESS;
  }

  ASSERT (Instance->RcvdPacketQueueSize != 0);

  RxDataWrap = NET_LIST_HEAD (&Instance->RcvdPacketQueue, MNP_RXDATA_WRAP, WrapEntry);
  if (RxDataWrap->Nbuf->RefCnt > 2) {
    //
    // There are other instances share this Nbuf, duplicate to get a
    // copy to allow the instance to do R/W operations.
    //
    DupNbuf = MnpAllocNbuf (MnpServiceData);
    if (DupNbuf == NULL) {
      DEBUG ((EFI_D_WARN, "MnpDeliverPacket: Failed to allocate a free Nbuf.\n"));

      return EFI_OUT_OF_RESOURCES;
    }

    //
    // Duplicate the net buffer.
    //
    NetbufDuplicate (RxDataWrap->Nbuf, DupNbuf, 0);
    MnpFreeNbuf (MnpServiceData, RxDataWrap->Nbuf);
    RxDataWrap->Nbuf = DupNbuf;
  }

  //
  // All resources are OK, remove the packet from the queue.
  //
  NetListRemoveHead (&Instance->RcvdPacketQueue);
  Instance->RcvdPacketQueueSize--;

  RxData  = &RxDataWrap->RxData;
  SnpMode = MnpServiceData->Snp->Mode;

  //
  // Set all the buffer pointers.
  //
  RxData->MediaHeader         = NetbufGetByte (RxDataWrap->Nbuf, 0, NULL);
  RxData->DestinationAddress  = RxData->MediaHeader;
  RxData->SourceAddress       = (UINT8 *) RxData->MediaHeader + SnpMode->HwAddressSize;
  RxData->PacketData          = (UINT8 *) RxData->MediaHeader + SnpMode->MediaHeaderSize;

  //
  // Insert this RxDataWrap into the delivered queue.
  //
  InsertTailList (&Instance->RxDeliveredPacketQueue, &RxDataWrap->WrapEntry);

  //
  // Get the receive token from the RxTokenMap.
  //
  RxToken = NetMapRemoveHead (&Instance->RxTokenMap, NULL);

  //
  // Signal this token's event.
  //
  RxToken->Packet.RxData  = &RxDataWrap->RxData;
  RxToken->Status         = EFI_SUCCESS;
  gBS->SignalEvent (RxToken->Event);

  return EFI_SUCCESS;
}


/**
  Deliver the received packet for the instances belonging to the MnpServiceData.

  @param  MnpServiceData        Pointer to the mnp service context data.

  @return None.

**/
STATIC
VOID
MnpDeliverPacket (
  IN MNP_SERVICE_DATA  *MnpServiceData
  )
{
  LIST_ENTRY        *Entry;
  MNP_INSTANCE_DATA *Instance;

  NET_CHECK_SIGNATURE (MnpServiceData, MNP_SERVICE_DATA_SIGNATURE);

  NET_LIST_FOR_EACH (Entry, &MnpServiceData->ChildrenList) {
    Instance = NET_LIST_USER_STRUCT (Entry, MNP_INSTANCE_DATA, InstEntry);
    NET_CHECK_SIGNATURE (Instance, MNP_INSTANCE_DATA_SIGNATURE);

    //
    // Try to deliver packet for this instance.
    //
    MnpInstanceDeliverPacket (Instance);
  }
}


/**
  Recycle the RxData and other resources used to hold and deliver the received
  packet.

  @param  Event                 The event this notify function registered to.
  @param  Context               Pointer to the context data registerd to the Event.

  @return None.

**/
VOID
EFIAPI
MnpRecycleRxData (
  IN EFI_EVENT  Event,
  IN VOID       *Context
  )
{
  MNP_RXDATA_WRAP   *RxDataWrap;
  MNP_SERVICE_DATA  *MnpServiceData;

  ASSERT (Context != NULL);

  RxDataWrap = (MNP_RXDATA_WRAP *) Context;
  NET_CHECK_SIGNATURE (RxDataWrap->Instance, MNP_INSTANCE_DATA_SIGNATURE);

  ASSERT (RxDataWrap->Nbuf != NULL);

  MnpServiceData = RxDataWrap->Instance->MnpServiceData;
  NET_CHECK_SIGNATURE (MnpServiceData, MNP_SERVICE_DATA_SIGNATURE);

  //
  // Free this Nbuf.
  //
  MnpFreeNbuf (MnpServiceData, RxDataWrap->Nbuf);
  RxDataWrap->Nbuf = NULL;

  //
  // Close the recycle event.
  //
  gBS->CloseEvent (RxDataWrap->RxData.RecycleEvent);

  //
  // Remove this Wrap entry from the list.
  //
  RemoveEntryList (&RxDataWrap->WrapEntry);

  gBS->FreePool (RxDataWrap);
}


/**
  Queue the received packet into instance's receive queue.

  @param  Instance              Pointer to the mnp instance context data.
  @param  RxDataWrap            Pointer to the Wrap structure containing the
                                received data and other information.

  @return None.

**/
STATIC
VOID
MnpQueueRcvdPacket (
  IN MNP_INSTANCE_DATA  *Instance,
  IN MNP_RXDATA_WRAP    *RxDataWrap
  )
{
  MNP_RXDATA_WRAP *OldRxDataWrap;

  NET_CHECK_SIGNATURE (Instance, MNP_INSTANCE_DATA_SIGNATURE);

  //
  // Check the queue size. If it exceeds the limit, drop one packet
  // from the head.
  //
  if (Instance->RcvdPacketQueueSize == MNP_MAX_RCVD_PACKET_QUE_SIZE) {

    DEBUG ((EFI_D_WARN, "MnpQueueRcvdPacket: Drop one packet bcz queue size limit reached.\n"));

    //
    // Get the oldest packet.
    //
    OldRxDataWrap = NET_LIST_HEAD (
                      &Instance->RcvdPacketQueue,
                      MNP_RXDATA_WRAP,
                      WrapEntry
                      );

    //
    // Recycle this OldRxDataWrap, this entry will be removed by the callee.
    //
    MnpRecycleRxData (NULL, (VOID *) OldRxDataWrap);
    Instance->RcvdPacketQueueSize--;
  }

  //
  // Update the timeout tick using the configured parameter.
  //
  RxDataWrap->TimeoutTick = Instance->ConfigData.ReceivedQueueTimeoutValue;

  //
  // Insert this Wrap into the instance queue.
  //
  InsertTailList (&Instance->RcvdPacketQueue, &RxDataWrap->WrapEntry);
  Instance->RcvdPacketQueueSize++;
}


/**
  Match the received packet with the instance receive filters.

  @param  Instance              Pointer to the mnp instance context data.
  @param  RxData                Pointer to the EFI_MANAGED_NETWORK_RECEIVE_DATA.
  @param  GroupAddress          Pointer to the GroupAddress, the GroupAddress is
                                non-NULL and it contains the destination multicast
                                mac address of the received packet if the packet
                                destinated to a multicast mac address.
  @param  PktAttr               The received packets attribute.

  @return The received packet matches the instance's receive filters or not.

**/
STATIC
BOOLEAN
MnpMatchPacket (
  IN MNP_INSTANCE_DATA                 *Instance,
  IN EFI_MANAGED_NETWORK_RECEIVE_DATA  *RxData,
  IN MNP_GROUP_ADDRESS                 *GroupAddress OPTIONAL,
  IN UINT8                             PktAttr
  )
{
  EFI_MANAGED_NETWORK_CONFIG_DATA *ConfigData;
  LIST_ENTRY                      *Entry;
  MNP_GROUP_CONTROL_BLOCK         *GroupCtrlBlk;

  NET_CHECK_SIGNATURE (Instance, MNP_INSTANCE_DATA_SIGNATURE);

  ConfigData = &Instance->ConfigData;

  //
  // Check the protocol type.
  //
  if ((ConfigData->ProtocolTypeFilter != 0) && (ConfigData->ProtocolTypeFilter != RxData->ProtocolType)) {
    return FALSE;
  }

  if (ConfigData->EnablePromiscuousReceive) {
    //
    // Always match if this instance is configured to be promiscuous.
    //
    return TRUE;
  }

  //
  // The protocol type is matched, check receive filter, include unicast and broadcast.
  //
  if ((Instance->ReceiveFilter & PktAttr) != 0) {
    return TRUE;
  }

  //
  // Check multicast addresses.
  //
  if (ConfigData->EnableMulticastReceive && RxData->MulticastFlag) {

    ASSERT (GroupAddress != NULL);

    NET_LIST_FOR_EACH (Entry, &Instance->GroupCtrlBlkList) {

      GroupCtrlBlk = NET_LIST_USER_STRUCT (Entry, MNP_GROUP_CONTROL_BLOCK, CtrlBlkEntry);
      if (GroupCtrlBlk->GroupAddress == GroupAddress) {
        //
        // The instance is configured to receiveing packets destinated to this
        // multicast address.
        //
        return TRUE;
      }
    }
  }

  //
  // No match.
  //
  return FALSE;
}


/**
  Analyse the received packets.

  @param  MnpServiceData        Pointer to the mnp service context data.
  @param  Nbuf                  Pointer to the net buffer holding the received
                                packet.
  @param  RxData                Pointer to the buffer used to save the analysed
                                result in EFI_MANAGED_NETWORK_RECEIVE_DATA.
  @param  GroupAddress          Pointer to pointer to a MNP_GROUP_ADDRESS used to
                                pass out the address of the multicast address the
                                received packet destinated to.
  @param  PktAttr               Pointer to the buffer used to save the analysed
                                packet attribute.

  @return None.

**/
STATIC
VOID
MnpAnalysePacket (
  IN  MNP_SERVICE_DATA                  *MnpServiceData,
  IN  NET_BUF                           *Nbuf,
  IN  EFI_MANAGED_NETWORK_RECEIVE_DATA  *RxData,
  OUT MNP_GROUP_ADDRESS                 **GroupAddress,
  OUT UINT8                             *PktAttr
  )
{
  EFI_SIMPLE_NETWORK_MODE *SnpMode;
  UINT8                   *BufPtr;
  LIST_ENTRY              *Entry;

  SnpMode = MnpServiceData->Snp->Mode;

  //
  // Get the packet buffer.
  //
  BufPtr = NetbufGetByte (Nbuf, 0, NULL);
  ASSERT (BufPtr != NULL);

  //
  // Set the initial values.
  //
  RxData->BroadcastFlag   = FALSE;
  RxData->MulticastFlag   = FALSE;
  RxData->PromiscuousFlag = FALSE;
  *PktAttr                = UNICAST_PACKET;

  if (!NET_MAC_EQUAL (&SnpMode->CurrentAddress, BufPtr, SnpMode->HwAddressSize)) {
    //
    // This packet isn't destinated to our current mac address, it't not unicast.
    //
    *PktAttr = 0;

    if (NET_MAC_EQUAL (&SnpMode->BroadcastAddress, BufPtr, SnpMode->HwAddressSize)) {
      //
      // It's broadcast.
      //
      RxData->BroadcastFlag = TRUE;
      *PktAttr              = BROADCAST_PACKET;
    } else if ((*BufPtr & 0x01) == 0x1) {
      //
      // It's multicast, try to match the multicast filters.
      //
      NET_LIST_FOR_EACH (Entry, &MnpServiceData->GroupAddressList) {

        *GroupAddress = NET_LIST_USER_STRUCT (Entry, MNP_GROUP_ADDRESS, AddrEntry);
        if (NET_MAC_EQUAL (BufPtr, &((*GroupAddress)->Address), SnpMode->HwAddressSize)) {
          RxData->MulticastFlag = TRUE;
          break;
        }
      }

      if (!RxData->MulticastFlag) {
        //
        // No match, set GroupAddress to NULL. This multicast packet must
        // be the result of PROMISUCOUS or PROMISUCOUS_MULTICAST flag is on.
        //
        *GroupAddress           = NULL;
        RxData->PromiscuousFlag = TRUE;

        if (MnpServiceData->PromiscuousCount == 0) {
          //
          // Skip the below code, there is no receiver of this packet.
          //
          return ;
        }
      }
    } else {
      RxData->PromiscuousFlag = TRUE;
    }
  }

  ZeroMem (&RxData->Timestamp, sizeof (EFI_TIME));

  //
  // Fill the common parts of RxData.
  //
  RxData->PacketLength  = Nbuf->TotalSize;
  RxData->HeaderLength  = SnpMode->MediaHeaderSize;
  RxData->AddressLength = SnpMode->HwAddressSize;
  RxData->DataLength    = RxData->PacketLength - RxData->HeaderLength;
  RxData->ProtocolType  = NTOHS (*(UINT16 *) (BufPtr + 2 * SnpMode->HwAddressSize));
}


/**
  Wrap the RxData.

  @param  Instance              Pointer to the mnp instance context data.
  @param  RxData                Pointer to the receive data to wrap.

  @return Pointer to a MNP_RXDATA_WRAP which wraps the RxData.

**/
STATIC
MNP_RXDATA_WRAP *
MnpWrapRxData (
  IN MNP_INSTANCE_DATA                 *Instance,
  IN EFI_MANAGED_NETWORK_RECEIVE_DATA  *RxData
  )
{
  EFI_STATUS      Status;
  MNP_RXDATA_WRAP *RxDataWrap;

  //
  // Allocate memory.
  //
  RxDataWrap = AllocatePool (sizeof (MNP_RXDATA_WRAP));
  if (RxDataWrap == NULL) {
    DEBUG ((EFI_D_ERROR, "MnpDispatchPacket: Failed to allocate a MNP_RXDATA_WRAP.\n"));
    return NULL;
  }

  RxDataWrap->Instance = Instance;

  //
  // Fill the RxData in RxDataWrap,
  //
  CopyMem (&RxDataWrap->RxData, RxData, sizeof (RxDataWrap->RxData));

  //
  // Create the recycle event.
  //
  Status = gBS->CreateEvent (
                  EVT_NOTIFY_SIGNAL,
                  TPL_NOTIFY,
                  MnpRecycleRxData,
                  RxDataWrap,
                  &RxDataWrap->RxData.RecycleEvent
                  );
  if (EFI_ERROR (Status)) {

    DEBUG ((EFI_D_ERROR, "MnpDispatchPacket: gBS->CreateEvent failed, %r.\n", Status));
    gBS->FreePool (RxDataWrap);
    return NULL;
  }

  return RxDataWrap;
}


/**
  Enqueue the received the packets to the instances belonging to the
  MnpServiceData.

  @param  MnpServiceData        Pointer to the mnp service context data.
  @param  Nbuf                  Pointer to the net buffer representing the received
                                packet.

  @return None.

**/
STATIC
VOID
MnpEnqueuePacket (
  IN MNP_SERVICE_DATA   *MnpServiceData,
  IN NET_BUF            *Nbuf
  )
{
  LIST_ENTRY                        *Entry;
  MNP_INSTANCE_DATA                 *Instance;
  EFI_MANAGED_NETWORK_RECEIVE_DATA  RxData;
  UINT8                             PktAttr;
  MNP_GROUP_ADDRESS                 *GroupAddress;
  MNP_RXDATA_WRAP                   *RxDataWrap;


  GroupAddress = NULL;
  //
  // First, analyse the packet header.
  //
  MnpAnalysePacket (MnpServiceData, Nbuf, &RxData, &GroupAddress, &PktAttr);

  if (RxData.PromiscuousFlag && (MnpServiceData->PromiscuousCount == 0)) {
    //
    // No receivers, no more action need.
    //
    return ;
  }

  //
  // Iterate the children to find match.
  //
  NET_LIST_FOR_EACH (Entry, &MnpServiceData->ChildrenList) {

    Instance = NET_LIST_USER_STRUCT (Entry, MNP_INSTANCE_DATA, InstEntry);
    NET_CHECK_SIGNATURE (Instance, MNP_INSTANCE_DATA_SIGNATURE);

    if (!Instance->Configured) {
      continue;
    }

    //
    // Check the packet against the instance receive filters.
    //
    if (MnpMatchPacket (Instance, &RxData, GroupAddress, PktAttr)) {

      //
      // Wrap the RxData.
      //
      RxDataWrap = MnpWrapRxData (Instance, &RxData);
      if (RxDataWrap == NULL) {
        continue;
      }

      //
      // Associate RxDataWrap with Nbuf and increase the RefCnt.
      //
      RxDataWrap->Nbuf = Nbuf;
      NET_GET_REF (RxDataWrap->Nbuf);

      //
      // Queue the packet into the instance queue.
      //
      MnpQueueRcvdPacket (Instance, RxDataWrap);
    }
  }
}


/**
  Try to receive a packet and deliver it.

  @param  MnpServiceData        Pointer to the mnp service context data.

  @retval EFI_SUCCESS           add return value to function comment
  @retval EFI_NOT_STARTED       The simple network protocol is not started.
  @retval EFI_NOT_READY         No packet received.
  @retval EFI_DEVICE_ERROR      An unexpected error occurs.

**/
EFI_STATUS
MnpReceivePacket (
  IN MNP_SERVICE_DATA  *MnpServiceData
  )
{
  EFI_STATUS                  Status;
  EFI_SIMPLE_NETWORK_PROTOCOL *Snp;
  NET_BUF                     *Nbuf;
  UINT8                       *BufPtr;
  UINTN                       BufLen;
  UINTN                       HeaderSize;
  UINT32                      Trimmed;

  NET_CHECK_SIGNATURE (MnpServiceData, MNP_SERVICE_DATA_SIGNATURE);

  Snp = MnpServiceData->Snp;
  if (Snp->Mode->State != EfiSimpleNetworkInitialized) {
    //
    // The simple network protocol is not started.
    //
    return EFI_NOT_STARTED;
  }

  if (IsListEmpty (&MnpServiceData->ChildrenList)) {
    //
    // There is no child, no need to receive packets.
    //
    return EFI_SUCCESS;
  }

  if (MnpServiceData->RxNbufCache == NULL) {
    //
    // Try to get a new buffer as there may be buffers recycled.
    //
    MnpServiceData->RxNbufCache = MnpAllocNbuf (MnpServiceData);

    if (MnpServiceData->RxNbufCache == NULL) {
      //
      // No availabe buffer in the buffer pool.
      //
      return EFI_DEVICE_ERROR;
    }

    NetbufAllocSpace (
      MnpServiceData->RxNbufCache,
      MnpServiceData->BufferLength,
      NET_BUF_TAIL
      );
  }

  Nbuf    = MnpServiceData->RxNbufCache;
  BufLen  = Nbuf->TotalSize;
  BufPtr  = NetbufGetByte (Nbuf, 0, NULL);
  ASSERT (BufPtr != NULL);

  //
  // Receive packet through Snp.
  //
  Status = Snp->Receive (Snp, &HeaderSize, &BufLen, BufPtr, NULL, NULL, NULL);
  if (EFI_ERROR (Status)) {

    DEBUG_CODE (
      if (Status != EFI_NOT_READY) {
      DEBUG ((EFI_D_ERROR, "MnpReceivePacket: Snp->Receive() = %r.\n", Status));
    }
    );

    return Status;
  }

  //
  // Sanity check.
  //
  if ((HeaderSize != Snp->Mode->MediaHeaderSize) || (BufLen < HeaderSize)) {

    DEBUG (
      (EFI_D_WARN,
      "MnpReceivePacket: Size error, HL:TL = %d:%d.\n",
      HeaderSize,
      BufLen)
      );
    return EFI_DEVICE_ERROR;
  }

  Trimmed = 0;
  if (Nbuf->TotalSize != BufLen) {
    //
    // Trim the packet from tail.
    //
    Trimmed = NetbufTrim (Nbuf, Nbuf->TotalSize - (UINT32) BufLen, NET_BUF_TAIL);
    ASSERT (Nbuf->TotalSize == BufLen);
  }

  //
  // Enqueue the packet to the matched instances.
  //
  MnpEnqueuePacket (MnpServiceData, Nbuf);

  if (Nbuf->RefCnt > 2) {
    //
    // RefCnt > 2 indicates there is at least one receiver of this packet.
    // Free the current RxNbufCache and allocate a new one.
    //
    MnpFreeNbuf (MnpServiceData, Nbuf);

    Nbuf                        = MnpAllocNbuf (MnpServiceData);
    MnpServiceData->RxNbufCache = Nbuf;
    if (Nbuf == NULL) {
      DEBUG ((EFI_D_ERROR, "MnpReceivePacket: Alloc packet for receiving cache failed.\n"));
      return EFI_DEVICE_ERROR;
    }

    NetbufAllocSpace (Nbuf, MnpServiceData->BufferLength, NET_BUF_TAIL);
  } else {
    //
    // No receiver for this packet.
    //
    if (Trimmed > 0) {
      NetbufAllocSpace (Nbuf, Trimmed, NET_BUF_TAIL);
    }

    goto EXIT;
  }
  //
  // Deliver the queued packets.
  //
  MnpDeliverPacket (MnpServiceData);

  //
  // Dispatch the DPC queued by the NotifyFunction of rx token's events.
  //
  NetLibDispatchDpc ();

EXIT:

  ASSERT (Nbuf->TotalSize == MnpServiceData->BufferLength);

  return Status;
}


/**
  Remove the received packets if timeout occurs.

  @param  Event                 The event this notify function registered to.
  @param  Context               Pointer to the context data registered to the
                                event.

  @return None.

**/
VOID
EFIAPI
MnpCheckPacketTimeout (
  IN EFI_EVENT  Event,
  IN VOID       *Context
  )
{
  MNP_SERVICE_DATA  *MnpServiceData;
  LIST_ENTRY        *Entry;
  LIST_ENTRY        *RxEntry;
  LIST_ENTRY        *NextEntry;
  MNP_INSTANCE_DATA *Instance;
  MNP_RXDATA_WRAP   *RxDataWrap;
  EFI_TPL           OldTpl;

  MnpServiceData = (MNP_SERVICE_DATA *) Context;
  NET_CHECK_SIGNATURE (MnpServiceData, MNP_SERVICE_DATA_SIGNATURE);

  NET_LIST_FOR_EACH (Entry, &MnpServiceData->ChildrenList) {

    Instance = NET_LIST_USER_STRUCT (Entry, MNP_INSTANCE_DATA, InstEntry);
    NET_CHECK_SIGNATURE (Instance, MNP_INSTANCE_DATA_SIGNATURE);

    if (!Instance->Configured || (Instance->ConfigData.ReceivedQueueTimeoutValue == 0)) {
      //
      // This instance is not configured or there is no receive time out,
      // just skip to the next instance.
      //
      continue;
    }

    OldTpl = gBS->RaiseTPL (TPL_NOTIFY);

    NET_LIST_FOR_EACH_SAFE (RxEntry, NextEntry, &Instance->RcvdPacketQueue) {

      RxDataWrap = NET_LIST_USER_STRUCT (RxEntry, MNP_RXDATA_WRAP, WrapEntry);

      if (RxDataWrap->TimeoutTick >= MNP_TIMEOUT_CHECK_INTERVAL) {

        RxDataWrap->TimeoutTick -= MNP_TIMEOUT_CHECK_INTERVAL;
      } else {
        //
        // Drop the timeout packet.
        //
        DEBUG ((EFI_D_WARN, "MnpCheckPacketTimeout: Received packet timeout.\n"));
        MnpRecycleRxData (NULL, RxDataWrap);
        Instance->RcvdPacketQueueSize--;
      }
    }

    gBS->RestoreTPL (OldTpl);
  }
}


/**
  Poll to receive the packets from Snp. This function is either called by upperlayer
  protocols/applications or the system poll timer notify mechanism.

  @param  Event                 The event this notify function registered to.
  @param  Context               Pointer to the context data registered to the
                                event.

  @return None.

**/
VOID
EFIAPI
MnpSystemPoll (
  IN EFI_EVENT  Event,
  IN VOID       *Context
  )
{
  MNP_SERVICE_DATA  *MnpServiceData;

  MnpServiceData = (MNP_SERVICE_DATA *) Context;
  NET_CHECK_SIGNATURE (MnpServiceData, MNP_SERVICE_DATA_SIGNATURE);

  //
  // Try to receive packets from Snp.
  //
  MnpReceivePacket (MnpServiceData);

  NetLibDispatchDpc ();
}