/** @file
  Network library.

Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>
(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
Copyright (c) Microsoft Corporation
SPDX-License-Identifier: BSD-2-Clause-Patent
**/

#include <Uefi.h>

#include <IndustryStandard/SmBios.h>

#include <Protocol/DriverBinding.h>
#include <Protocol/ServiceBinding.h>
#include <Protocol/SimpleNetwork.h>
#include <Protocol/AdapterInformation.h>
#include <Protocol/ManagedNetwork.h>
#include <Protocol/Ip4Config2.h>
#include <Protocol/ComponentName.h>
#include <Protocol/ComponentName2.h>

#include <Guid/SmBios.h>

#include <Library/NetLib.h>
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiRuntimeServicesTableLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/DevicePathLib.h>
#include <Library/PrintLib.h>
#include <Library/UefiLib.h>
#include <Protocol/Rng.h>

#define NIC_ITEM_CONFIG_SIZE  (sizeof (NIC_IP4_CONFIG_INFO) + sizeof (EFI_IP4_ROUTE_TABLE) * MAX_IP4_CONFIG_IN_VARIABLE)
#define DEFAULT_ZERO_START    ((UINTN) ~0)

//
// All the supported IP4 masks in host byte order.
//
GLOBAL_REMOVE_IF_UNREFERENCED IP4_ADDR  gIp4AllMasks[IP4_MASK_NUM] = {
  0x00000000,
  0x80000000,
  0xC0000000,
  0xE0000000,
  0xF0000000,
  0xF8000000,
  0xFC000000,
  0xFE000000,

  0xFF000000,
  0xFF800000,
  0xFFC00000,
  0xFFE00000,
  0xFFF00000,
  0xFFF80000,
  0xFFFC0000,
  0xFFFE0000,

  0xFFFF0000,
  0xFFFF8000,
  0xFFFFC000,
  0xFFFFE000,
  0xFFFFF000,
  0xFFFFF800,
  0xFFFFFC00,
  0xFFFFFE00,

  0xFFFFFF00,
  0xFFFFFF80,
  0xFFFFFFC0,
  0xFFFFFFE0,
  0xFFFFFFF0,
  0xFFFFFFF8,
  0xFFFFFFFC,
  0xFFFFFFFE,
  0xFFFFFFFF,
};

GLOBAL_REMOVE_IF_UNREFERENCED EFI_IPv4_ADDRESS  mZeroIp4Addr = {
  { 0, 0, 0, 0 }
};

//
// Any error level digitally larger than mNetDebugLevelMax
// will be silently discarded.
//
GLOBAL_REMOVE_IF_UNREFERENCED UINTN   mNetDebugLevelMax = NETDEBUG_LEVEL_ERROR;
GLOBAL_REMOVE_IF_UNREFERENCED UINT32  mSyslogPacketSeq  = 0xDEADBEEF;

//
// You can change mSyslogDstMac mSyslogDstIp and mSyslogSrcIp
// here to direct the syslog packets to the syslog deamon. The
// default is broadcast to both the ethernet and IP.
//
GLOBAL_REMOVE_IF_UNREFERENCED UINT8   mSyslogDstMac[NET_ETHER_ADDR_LEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
GLOBAL_REMOVE_IF_UNREFERENCED UINT32  mSyslogDstIp                      = 0xffffffff;
GLOBAL_REMOVE_IF_UNREFERENCED UINT32  mSyslogSrcIp                      = 0;

GLOBAL_REMOVE_IF_UNREFERENCED CHAR8  *mMonthName[] = {
  "Jan",
  "Feb",
  "Mar",
  "Apr",
  "May",
  "Jun",
  "Jul",
  "Aug",
  "Sep",
  "Oct",
  "Nov",
  "Dec"
};

//
// VLAN device path node template
//
GLOBAL_REMOVE_IF_UNREFERENCED VLAN_DEVICE_PATH  mNetVlanDevicePathTemplate = {
  {
    MESSAGING_DEVICE_PATH,
    MSG_VLAN_DP,
    {
      (UINT8)(sizeof (VLAN_DEVICE_PATH)),
      (UINT8)((sizeof (VLAN_DEVICE_PATH)) >> 8)
    }
  },
  0
};

//
// These represent UEFI SPEC defined algorithms that should be supported by
// the RNG protocol and are generally considered secure.
//
// Assuming that PcdEnforceSecureRngAlgorithms is TRUE (the default) then
// only the algorithms defined here will be used by the network stack, and
// none of these being available will result in an error condition (even if
// some other RNG implementation is available).
//
// If PcdEnforceSecureRngAlgorithms is FALSE this list is not consulted,
// and the first available RNG algorithm is used.
//
// If your platform needs to use a specific algorithm for the random number
// generator, then you should modify this array.
//
static EFI_GUID *CONST  mSecureHashAlgorithms[] = {
  &gEfiRngAlgorithmSp80090Ctr256Guid,  // SP800-90A DRBG CTR using AES-256
  &gEfiRngAlgorithmSp80090Hmac256Guid, // SP800-90A DRBG HMAC using SHA-256
  &gEfiRngAlgorithmSp80090Hash256Guid, // SP800-90A DRBG Hash using SHA-256
  &gEfiRngAlgorithmArmRndr,            // unspecified SP800-90A DRBG via ARM RNDR register
  &gEfiRngAlgorithmRaw,                // Raw data from NRBG (or TRNG)
};

#define SECURE_HASH_ALGORITHMS_SIZE  (sizeof (mSecureHashAlgorithms) / sizeof (EFI_GUID *))

/**
  Locate the handles that support SNP, then open one of them
  to send the syslog packets. The caller isn't required to close
  the SNP after use because the SNP is opened by HandleProtocol.

  @return The point to SNP if one is properly opened. Otherwise NULL

**/
EFI_SIMPLE_NETWORK_PROTOCOL *
SyslogLocateSnp (
  VOID
  )
{
  EFI_SIMPLE_NETWORK_PROTOCOL  *Snp;
  EFI_STATUS                   Status;
  EFI_HANDLE                   *Handles;
  UINTN                        HandleCount;
  UINTN                        Index;

  //
  // Locate the handles which has SNP installed.
  //
  Handles = NULL;
  Status  = gBS->LocateHandleBuffer (
                   ByProtocol,
                   &gEfiSimpleNetworkProtocolGuid,
                   NULL,
                   &HandleCount,
                   &Handles
                   );

  if (EFI_ERROR (Status) || (HandleCount == 0)) {
    return NULL;
  }

  //
  // Try to open one of the ethernet SNP protocol to send packet
  //
  Snp = NULL;

  for (Index = 0; Index < HandleCount; Index++) {
    Status = gBS->HandleProtocol (
                    Handles[Index],
                    &gEfiSimpleNetworkProtocolGuid,
                    (VOID **)&Snp
                    );

    if ((Status == EFI_SUCCESS) && (Snp != NULL) &&
        (Snp->Mode->IfType == NET_IFTYPE_ETHERNET) &&
        (Snp->Mode->MaxPacketSize >= NET_SYSLOG_PACKET_LEN))
    {
      break;
    }

    Snp = NULL;
  }

  FreePool (Handles);
  return Snp;
}

/**
  Transmit a syslog packet synchronously through SNP. The Packet
  already has the ethernet header prepended. This function should
  fill in the source MAC because it will try to locate a SNP each
  time it is called to avoid the problem if SNP is unloaded.
  This code snip is copied from MNP.
  If Packet is NULL, then ASSERT().

  @param[in] Packet          The Syslog packet
  @param[in] Length          The length of the packet

  @retval EFI_DEVICE_ERROR   Failed to locate a usable SNP protocol
  @retval EFI_TIMEOUT        Timeout happened to send the packet.
  @retval EFI_SUCCESS        Packet is sent.

**/
EFI_STATUS
SyslogSendPacket (
  IN CHAR8   *Packet,
  IN UINT32  Length
  )
{
  EFI_SIMPLE_NETWORK_PROTOCOL  *Snp;
  ETHER_HEAD                   *Ether;
  EFI_STATUS                   Status;
  EFI_EVENT                    TimeoutEvent;
  UINT8                        *TxBuf;

  ASSERT (Packet != NULL);

  Snp = SyslogLocateSnp ();

  if (Snp == NULL) {
    return EFI_DEVICE_ERROR;
  }

  Ether = (ETHER_HEAD *)Packet;
  CopyMem (Ether->SrcMac, Snp->Mode->CurrentAddress.Addr, NET_ETHER_ADDR_LEN);

  //
  // Start the timeout event.
  //
  Status = gBS->CreateEvent (
                  EVT_TIMER,
                  TPL_NOTIFY,
                  NULL,
                  NULL,
                  &TimeoutEvent
                  );

  if (EFI_ERROR (Status)) {
    return Status;
  }

  Status = gBS->SetTimer (TimeoutEvent, TimerRelative, NET_SYSLOG_TX_TIMEOUT);

  if (EFI_ERROR (Status)) {
    goto ON_EXIT;
  }

  for ( ; ;) {
    //
    // Transmit the packet through SNP.
    //
    Status = Snp->Transmit (Snp, 0, Length, Packet, NULL, NULL, NULL);

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

    if ((Status == EFI_SUCCESS) || (Status == EFI_TIMEOUT)) {
      break;
    }

    //
    // Status is EFI_NOT_READY. Restart the timer event and
    // call Snp->Transmit again.
    //
    gBS->SetTimer (TimeoutEvent, TimerRelative, NET_SYSLOG_TX_TIMEOUT);
  }

  gBS->SetTimer (TimeoutEvent, TimerCancel, 0);

ON_EXIT:
  gBS->CloseEvent (TimeoutEvent);
  return Status;
}

/**
  Build a syslog packet, including the Ethernet/Ip/Udp headers
  and user's message.

  @param[in]  Level     Syslog severity level
  @param[in]  Module    The module that generates the log
  @param[in]  File      The file that contains the current log
  @param[in]  Line      The line of code in the File that contains the current log
  @param[in]  Message   The log message
  @param[in]  BufLen    The length of the Buf
  @param[out] Buf       The buffer to put the packet data

  @return The length of the syslog packet built, 0 represents no packet is built.

**/
UINT32
SyslogBuildPacket (
  IN  UINT32  Level,
  IN  UINT8   *Module,
  IN  UINT8   *File,
  IN  UINT32  Line,
  IN  UINT8   *Message,
  IN  UINT32  BufLen,
  OUT CHAR8   *Buf
  )
{
  EFI_STATUS      Status;
  ETHER_HEAD      *Ether;
  IP4_HEAD        *Ip4;
  EFI_UDP_HEADER  *Udp4;
  EFI_TIME        Time;
  UINT32          Pri;
  UINT32          Len;

  //
  // Fill in the Ethernet header. Leave alone the source MAC.
  // SyslogSendPacket will fill in the address for us.
  //
  Ether = (ETHER_HEAD *)Buf;
  CopyMem (Ether->DstMac, mSyslogDstMac, NET_ETHER_ADDR_LEN);
  ZeroMem (Ether->SrcMac, NET_ETHER_ADDR_LEN);

  Ether->EtherType = HTONS (0x0800);    // IPv4 protocol

  Buf    += sizeof (ETHER_HEAD);
  BufLen -= sizeof (ETHER_HEAD);

  //
  // Fill in the IP header
  //
  Ip4           = (IP4_HEAD *)Buf;
  Ip4->HeadLen  = 5;
  Ip4->Ver      = 4;
  Ip4->Tos      = 0;
  Ip4->TotalLen = 0;
  Ip4->Id       = (UINT16)mSyslogPacketSeq;
  Ip4->Fragment = 0;
  Ip4->Ttl      = 16;
  Ip4->Protocol = 0x11;
  Ip4->Checksum = 0;
  Ip4->Src      = mSyslogSrcIp;
  Ip4->Dst      = mSyslogDstIp;

  Buf    += sizeof (IP4_HEAD);
  BufLen -= sizeof (IP4_HEAD);

  //
  // Fill in the UDP header, Udp checksum is optional. Leave it zero.
  //
  Udp4           = (EFI_UDP_HEADER *)Buf;
  Udp4->SrcPort  = HTONS (514);
  Udp4->DstPort  = HTONS (514);
  Udp4->Length   = 0;
  Udp4->Checksum = 0;

  Buf    += sizeof (EFI_UDP_HEADER);
  BufLen -= sizeof (EFI_UDP_HEADER);

  //
  // Build the syslog message body with <PRI> Timestamp  machine module Message
  //
  Pri    = ((NET_SYSLOG_FACILITY & 31) << 3) | (Level & 7);
  Status = gRT->GetTime (&Time, NULL);
  if (EFI_ERROR (Status)) {
    return 0;
  }

  //
  // Use %a to format the ASCII strings, %s to format UNICODE strings
  //
  Len  = 0;
  Len += (UINT32)AsciiSPrint (
                   Buf,
                   BufLen,
                   "<%d> %a %d %d:%d:%d ",
                   Pri,
                   mMonthName[Time.Month-1],
                   Time.Day,
                   Time.Hour,
                   Time.Minute,
                   Time.Second
                   );

  Len += (UINT32)AsciiSPrint (
                   Buf + Len,
                   BufLen - Len,
                   "Tiano %a: %a (Line: %d File: %a)",
                   Module,
                   Message,
                   Line,
                   File
                   );
  Len++;

  //
  // OK, patch the IP length/checksum and UDP length fields.
  //
  Len         += sizeof (EFI_UDP_HEADER);
  Udp4->Length = HTONS ((UINT16)Len);

  Len          += sizeof (IP4_HEAD);
  Ip4->TotalLen = HTONS ((UINT16)Len);
  Ip4->Checksum = (UINT16)(~NetblockChecksum ((UINT8 *)Ip4, sizeof (IP4_HEAD)));

  return Len + sizeof (ETHER_HEAD);
}

/**
  Allocate a buffer, then format the message to it. This is a
  help function for the NET_DEBUG_XXX macros. The PrintArg of
  these macros treats the variable length print parameters as a
  single parameter, and pass it to the NetDebugASPrint. For
  example, NET_DEBUG_TRACE ("Tcp", ("State transit to %a\n", Name))
  if extracted to:

         NetDebugOutput (
           NETDEBUG_LEVEL_TRACE,
           "Tcp",
           __FILE__,
           DEBUG_LINE_NUMBER,
           NetDebugASPrint ("State transit to %a\n", Name)
         )

  If Format is NULL, then ASSERT().

  @param Format  The ASCII format string.
  @param ...     The variable length parameter whose format is determined
                 by the Format string.

  @return        The buffer containing the formatted message,
                 or NULL if failed to allocate memory.

**/
CHAR8 *
EFIAPI
NetDebugASPrint (
  IN CHAR8  *Format,
  ...
  )
{
  VA_LIST  Marker;
  CHAR8    *Buf;

  ASSERT (Format != NULL);

  Buf = (CHAR8 *)AllocatePool (NET_DEBUG_MSG_LEN);

  if (Buf == NULL) {
    return NULL;
  }

  VA_START (Marker, Format);
  AsciiVSPrint (Buf, NET_DEBUG_MSG_LEN, Format, Marker);
  VA_END (Marker);

  return Buf;
}

/**
  Builds an UDP4 syslog packet and send it using SNP.

  This function will locate a instance of SNP then send the message through it.
  Because it isn't open the SNP BY_DRIVER, apply caution when using it.

  @param Level    The severity level of the message.
  @param Module   The Module that generates the log.
  @param File     The file that contains the log.
  @param Line     The exact line that contains the log.
  @param Message  The user message to log.

  @retval EFI_INVALID_PARAMETER Any input parameter is invalid.
  @retval EFI_OUT_OF_RESOURCES  Failed to allocate memory for the packet.
  @retval EFI_DEVICE_ERROR      Device error occurs.
  @retval EFI_SUCCESS           The log is discard because that it is more verbose
                                than the mNetDebugLevelMax. Or, it has been sent out.
**/
EFI_STATUS
EFIAPI
NetDebugOutput (
  IN UINT32  Level,
  IN UINT8   *Module,
  IN UINT8   *File,
  IN UINT32  Line,
  IN UINT8   *Message
  )
{
  CHAR8       *Packet;
  UINT32      Len;
  EFI_STATUS  Status;

  //
  // Check whether the message should be sent out
  //
  if ((Message == NULL) || (File == NULL) || (Module == NULL)) {
    return EFI_INVALID_PARAMETER;
  }

  if (Level > mNetDebugLevelMax) {
    Status = EFI_SUCCESS;
    goto ON_EXIT;
  }

  //
  // Allocate a maximum of 1024 bytes, the caller should ensure
  // that the message plus the ethernet/ip/udp header is shorter
  // than this
  //
  Packet = (CHAR8 *)AllocatePool (NET_SYSLOG_PACKET_LEN);

  if (Packet == NULL) {
    Status = EFI_OUT_OF_RESOURCES;
    goto ON_EXIT;
  }

  //
  // Build the message: Ethernet header + IP header + Udp Header + user data
  //
  Len = SyslogBuildPacket (
          Level,
          Module,
          File,
          Line,
          Message,
          NET_SYSLOG_PACKET_LEN,
          Packet
          );
  if (Len == 0) {
    Status = EFI_DEVICE_ERROR;
  } else {
    mSyslogPacketSeq++;
    Status = SyslogSendPacket (Packet, Len);
  }

  FreePool (Packet);

ON_EXIT:
  FreePool (Message);
  return Status;
}

/**
  Return the length of the mask.

  Return the length of the mask, the correct value is from 0 to 32.
  If the mask is invalid, return the invalid length 33, which is IP4_MASK_NUM.
  NetMask is in the host byte order.

  @param[in]  NetMask              The netmask to get the length from.

  @return The length of the netmask, IP4_MASK_NUM if the mask is invalid.

**/
INTN
EFIAPI
NetGetMaskLength (
  IN IP4_ADDR  NetMask
  )
{
  INTN  Index;

  for (Index = 0; Index <= IP4_MASK_MAX; Index++) {
    if (NetMask == gIp4AllMasks[Index]) {
      break;
    }
  }

  return Index;
}

/**
  Return the class of the IP address, such as class A, B, C.
  Addr is in host byte order.

  [ATTENTION]
  Classful addressing (IP class A/B/C) has been deprecated according to RFC4632.
  Caller of this function could only check the returned value against
  IP4_ADDR_CLASSD (multicast) or IP4_ADDR_CLASSE (reserved) now.

  The address of class A  starts with 0.
  If the address belong to class A, return IP4_ADDR_CLASSA.
  The address of class B  starts with 10.
  If the address belong to class B, return IP4_ADDR_CLASSB.
  The address of class C  starts with 110.
  If the address belong to class C, return IP4_ADDR_CLASSC.
  The address of class D  starts with 1110.
  If the address belong to class D, return IP4_ADDR_CLASSD.
  The address of class E  starts with 1111.
  If the address belong to class E, return IP4_ADDR_CLASSE.


  @param[in]   Addr                  The address to get the class from.

  @return IP address class, such as IP4_ADDR_CLASSA.

**/
INTN
EFIAPI
NetGetIpClass (
  IN IP4_ADDR  Addr
  )
{
  UINT8  ByteOne;

  ByteOne = (UINT8)(Addr >> 24);

  if ((ByteOne & 0x80) == 0) {
    return IP4_ADDR_CLASSA;
  } else if ((ByteOne & 0xC0) == 0x80) {
    return IP4_ADDR_CLASSB;
  } else if ((ByteOne & 0xE0) == 0xC0) {
    return IP4_ADDR_CLASSC;
  } else if ((ByteOne & 0xF0) == 0xE0) {
    return IP4_ADDR_CLASSD;
  } else {
    return IP4_ADDR_CLASSE;
  }
}

/**
  Check whether the IP is a valid unicast address according to
  the netmask.

  ASSERT if NetMask is zero.

  If all bits of the host address of IP are 0 or 1, IP is also not a valid unicast address,
  except when the originator is one of the endpoints of a point-to-point link with a 31-bit
  mask (RFC3021), or a 32bit NetMask (all 0xFF) is used for special network environment (e.g.
  PPP link).

  @param[in]  Ip                    The IP to check against.
  @param[in]  NetMask               The mask of the IP.

  @return TRUE if IP is a valid unicast address on the network, otherwise FALSE.

**/
BOOLEAN
EFIAPI
NetIp4IsUnicast (
  IN IP4_ADDR  Ip,
  IN IP4_ADDR  NetMask
  )
{
  INTN  MaskLength;

  ASSERT (NetMask != 0);

  if ((Ip == 0) || IP4_IS_LOCAL_BROADCAST (Ip)) {
    return FALSE;
  }

  MaskLength = NetGetMaskLength (NetMask);
  ASSERT ((MaskLength >= 0) && (MaskLength <= IP4_MASK_NUM));
  if (MaskLength < 31) {
    if (((Ip &~NetMask) == ~NetMask) || ((Ip &~NetMask) == 0)) {
      return FALSE;
    }
  }

  return TRUE;
}

/**
  Check whether the incoming IPv6 address is a valid unicast address.

  ASSERT if Ip6 is NULL.

  If the address is a multicast address has binary 0xFF at the start, it is not
  a valid unicast address. If the address is unspecified ::, it is not a valid
  unicast address to be assigned to any node. If the address is loopback address
  ::1, it is also not a valid unicast address to be assigned to any physical
  interface.

  @param[in]  Ip6                   The IPv6 address to check against.

  @return TRUE if Ip6 is a valid unicast address on the network, otherwise FALSE.

**/
BOOLEAN
EFIAPI
NetIp6IsValidUnicast (
  IN EFI_IPv6_ADDRESS  *Ip6
  )
{
  UINT8  Byte;
  UINT8  Index;

  ASSERT (Ip6 != NULL);

  if (Ip6->Addr[0] == 0xFF) {
    return FALSE;
  }

  for (Index = 0; Index < 15; Index++) {
    if (Ip6->Addr[Index] != 0) {
      return TRUE;
    }
  }

  Byte = Ip6->Addr[Index];

  if ((Byte == 0x0) || (Byte == 0x1)) {
    return FALSE;
  }

  return TRUE;
}

/**
  Check whether the incoming Ipv6 address is the unspecified address or not.

  ASSERT if Ip6 is NULL.

  @param[in] Ip6   - Ip6 address, in network order.

  @retval TRUE     - Yes, unspecified
  @retval FALSE    - No

**/
BOOLEAN
EFIAPI
NetIp6IsUnspecifiedAddr (
  IN EFI_IPv6_ADDRESS  *Ip6
  )
{
  UINT8  Index;

  ASSERT (Ip6 != NULL);

  for (Index = 0; Index < 16; Index++) {
    if (Ip6->Addr[Index] != 0) {
      return FALSE;
    }
  }

  return TRUE;
}

/**
  Check whether the incoming Ipv6 address is a link-local address.

  ASSERT if Ip6 is NULL.

  @param[in] Ip6   - Ip6 address, in network order.

  @retval TRUE  - Yes, link-local address
  @retval FALSE - No

**/
BOOLEAN
EFIAPI
NetIp6IsLinkLocalAddr (
  IN EFI_IPv6_ADDRESS  *Ip6
  )
{
  UINT8  Index;

  ASSERT (Ip6 != NULL);

  if (Ip6->Addr[0] != 0xFE) {
    return FALSE;
  }

  if (Ip6->Addr[1] != 0x80) {
    return FALSE;
  }

  for (Index = 2; Index < 8; Index++) {
    if (Ip6->Addr[Index] != 0) {
      return FALSE;
    }
  }

  return TRUE;
}

/**
  Check whether the Ipv6 address1 and address2 are on the connected network.

  ASSERT if Ip1 or Ip2 is NULL.
  ASSERT if PrefixLength exceeds or equals to IP6_PREFIX_MAX.

  @param[in] Ip1          - Ip6 address1, in network order.
  @param[in] Ip2          - Ip6 address2, in network order.
  @param[in] PrefixLength - The prefix length of the checking net.

  @retval TRUE            - Yes, connected.
  @retval FALSE           - No.

**/
BOOLEAN
EFIAPI
NetIp6IsNetEqual (
  EFI_IPv6_ADDRESS  *Ip1,
  EFI_IPv6_ADDRESS  *Ip2,
  UINT8             PrefixLength
  )
{
  UINT8  Byte;
  UINT8  Bit;
  UINT8  Mask;

  ASSERT ((Ip1 != NULL) && (Ip2 != NULL) && (PrefixLength < IP6_PREFIX_MAX));

  if (PrefixLength == 0) {
    return TRUE;
  }

  Byte = (UINT8)(PrefixLength / 8);
  Bit  = (UINT8)(PrefixLength % 8);

  if (CompareMem (Ip1, Ip2, Byte) != 0) {
    return FALSE;
  }

  if (Bit > 0) {
    Mask = (UINT8)(0xFF << (8 - Bit));

    ASSERT (Byte < 16);
    if (Byte >= 16) {
      return FALSE;
    }

    if ((Ip1->Addr[Byte] & Mask) != (Ip2->Addr[Byte] & Mask)) {
      return FALSE;
    }
  }

  return TRUE;
}

/**
  Switches the endianess of an IPv6 address

  ASSERT if Ip6 is NULL.

  This function swaps the bytes in a 128-bit IPv6 address to switch the value
  from little endian to big endian or vice versa. The byte swapped value is
  returned.

  @param  Ip6 Points to an IPv6 address

  @return The byte swapped IPv6 address.

**/
EFI_IPv6_ADDRESS *
EFIAPI
Ip6Swap128 (
  EFI_IPv6_ADDRESS  *Ip6
  )
{
  UINT64  High;
  UINT64  Low;

  ASSERT (Ip6 != NULL);

  CopyMem (&High, Ip6, sizeof (UINT64));
  CopyMem (&Low, &Ip6->Addr[8], sizeof (UINT64));

  High = SwapBytes64 (High);
  Low  = SwapBytes64 (Low);

  CopyMem (Ip6, &Low, sizeof (UINT64));
  CopyMem (&Ip6->Addr[8], &High, sizeof (UINT64));

  return Ip6;
}

/**
  Generate a Random output data given a length.

  @param[out] Output - The buffer to store the generated random data.
  @param[in] OutputLength - The length of the output buffer.

  @retval EFI_SUCCESS           On Success
  @retval EFI_INVALID_PARAMETER Pointer is null or size is zero
  @retval EFI_NOT_FOUND         RNG protocol not found
  @retval Others                Error from RngProtocol->GetRNG()

  @return Status code
**/
EFI_STATUS
EFIAPI
PseudoRandom (
  OUT  VOID   *Output,
  IN   UINTN  OutputLength
  )
{
  EFI_RNG_PROTOCOL  *RngProtocol;
  EFI_STATUS        Status;
  UINTN             AlgorithmIndex;

  if ((Output == NULL) || (OutputLength == 0)) {
    return EFI_INVALID_PARAMETER;
  }

  Status = gBS->LocateProtocol (&gEfiRngProtocolGuid, NULL, (VOID **)&RngProtocol);
  if (EFI_ERROR (Status)) {
    DEBUG ((DEBUG_ERROR, "Failed to locate EFI_RNG_PROTOCOL: %r\n", Status));
    ASSERT_EFI_ERROR (Status);
    return Status;
  }

  if (PcdGetBool (PcdEnforceSecureRngAlgorithms)) {
    for (AlgorithmIndex = 0; AlgorithmIndex < SECURE_HASH_ALGORITHMS_SIZE; AlgorithmIndex++) {
      Status = RngProtocol->GetRNG (RngProtocol, mSecureHashAlgorithms[AlgorithmIndex], OutputLength, (UINT8 *)Output);
      if (!EFI_ERROR (Status)) {
        //
        // Secure Algorithm was supported on this platform
        //
        return EFI_SUCCESS;
      } else if (Status == EFI_UNSUPPORTED) {
        //
        // Secure Algorithm was not supported on this platform
        //
        DEBUG ((DEBUG_VERBOSE, "Failed to generate random data using secure algorithm %d: %r\n", AlgorithmIndex, Status));

        //
        // Try the next secure algorithm
        //
        continue;
      } else {
        //
        // Some other error occurred
        //
        DEBUG ((DEBUG_ERROR, "Failed to generate random data using secure algorithm %d: %r\n", AlgorithmIndex, Status));
        ASSERT_EFI_ERROR (Status);
        return Status;
      }
    }

    //
    // If we get here, we failed to generate random data using any secure algorithm
    // Platform owner should ensure that at least one secure algorithm is supported
    //
    DEBUG ((DEBUG_ERROR, "Failed to generate random data, no supported secure algorithm found\n"));
    ASSERT_EFI_ERROR (Status);
    return Status;
  }

  //
  // Lets try using the default algorithm (which may not be secure)
  //
  Status = RngProtocol->GetRNG (RngProtocol, NULL, OutputLength, (UINT8 *)Output);
  if (EFI_ERROR (Status)) {
    DEBUG ((DEBUG_ERROR, "%a failed to generate random data: %r\n", __func__, Status));
    ASSERT_EFI_ERROR (Status);
    return Status;
  }

  return EFI_SUCCESS;
}

/**
  Generate a 32-bit pseudo-random number.

  @param[out] Output - The buffer to store the generated random number.

  @retval EFI_SUCCESS           On Success
  @retval EFI_NOT_FOUND         RNG protocol not found
  @retval Others                Error from RngProtocol->GetRNG()

  @return Status code
**/
EFI_STATUS
EFIAPI
PseudoRandomU32 (
  OUT UINT32  *Output
  )
{
  return PseudoRandom (Output, sizeof (*Output));
}

/**
  Extract a UINT32 from a byte stream.

  ASSERT if Buf is NULL.

  Copy a UINT32 from a byte stream, then converts it from Network
  byte order to host byte order. Use this function to avoid alignment error.

  @param[in]  Buf                 The buffer to extract the UINT32.

  @return The UINT32 extracted.

**/
UINT32
EFIAPI
NetGetUint32 (
  IN UINT8  *Buf
  )
{
  UINT32  Value;

  ASSERT (Buf != NULL);

  CopyMem (&Value, Buf, sizeof (UINT32));
  return NTOHL (Value);
}

/**
  Put a UINT32 to the byte stream in network byte order.

  ASSERT if Buf is NULL.

  Converts a UINT32 from host byte order to network byte order. Then copy it to the
  byte stream.

  @param[in, out]  Buf          The buffer to put the UINT32.
  @param[in]       Data         The data to be converted and put into the byte stream.

**/
VOID
EFIAPI
NetPutUint32 (
  IN OUT UINT8   *Buf,
  IN     UINT32  Data
  )
{
  ASSERT (Buf != NULL);

  Data = HTONL (Data);
  CopyMem (Buf, &Data, sizeof (UINT32));
}

/**
  Remove the first node entry on the list, and return the removed node entry.

  Removes the first node Entry from a doubly linked list. It is up to the caller of
  this function to release the memory used by the first node if that is required. On
  exit, the removed node is returned.

  If Head is NULL, then ASSERT().
  If Head was not initialized, then ASSERT().
  If PcdMaximumLinkedListLength is not zero, and the number of nodes in the
  linked list including the head node is greater than or equal to PcdMaximumLinkedListLength,
  then ASSERT().

  @param[in, out]  Head                  The list header.

  @return The first node entry that is removed from the list, NULL if the list is empty.

**/
LIST_ENTRY *
EFIAPI
NetListRemoveHead (
  IN OUT LIST_ENTRY  *Head
  )
{
  LIST_ENTRY  *First;

  ASSERT (Head != NULL);

  if (IsListEmpty (Head)) {
    return NULL;
  }

  First                        = Head->ForwardLink;
  Head->ForwardLink            = First->ForwardLink;
  First->ForwardLink->BackLink = Head;

  DEBUG_CODE (
    First->ForwardLink = (LIST_ENTRY *)NULL;
    First->BackLink    = (LIST_ENTRY *)NULL;
    );

  return First;
}

/**
  Remove the last node entry on the list and and return the removed node entry.

  Removes the last node entry from a doubly linked list. It is up to the caller of
  this function to release the memory used by the first node if that is required. On
  exit, the removed node is returned.

  If Head is NULL, then ASSERT().
  If Head was not initialized, then ASSERT().
  If PcdMaximumLinkedListLength is not zero, and the number of nodes in the
  linked list including the head node is greater than or equal to PcdMaximumLinkedListLength,
  then ASSERT().

  @param[in, out]  Head                  The list head.

  @return The last node entry that is removed from the list, NULL if the list is empty.

**/
LIST_ENTRY *
EFIAPI
NetListRemoveTail (
  IN OUT LIST_ENTRY  *Head
  )
{
  LIST_ENTRY  *Last;

  ASSERT (Head != NULL);

  if (IsListEmpty (Head)) {
    return NULL;
  }

  Last                        = Head->BackLink;
  Head->BackLink              = Last->BackLink;
  Last->BackLink->ForwardLink = Head;

  DEBUG_CODE (
    Last->ForwardLink = (LIST_ENTRY *)NULL;
    Last->BackLink    = (LIST_ENTRY *)NULL;
    );

  return Last;
}

/**
  Insert a new node entry after a designated node entry of a doubly linked list.

  ASSERT if PrevEntry or NewEntry is NULL.

  Inserts a new node entry donated by NewEntry after the node entry donated by PrevEntry
  of the doubly linked list.

  @param[in, out]  PrevEntry             The previous entry to insert after.
  @param[in, out]  NewEntry              The new entry to insert.

**/
VOID
EFIAPI
NetListInsertAfter (
  IN OUT LIST_ENTRY  *PrevEntry,
  IN OUT LIST_ENTRY  *NewEntry
  )
{
  ASSERT (PrevEntry != NULL && NewEntry != NULL);

  NewEntry->BackLink               = PrevEntry;
  NewEntry->ForwardLink            = PrevEntry->ForwardLink;
  PrevEntry->ForwardLink->BackLink = NewEntry;
  PrevEntry->ForwardLink           = NewEntry;
}

/**
  Insert a new node entry before a designated node entry of a doubly linked list.

  ASSERT if PostEntry or NewEntry is NULL.

  Inserts a new node entry donated by NewEntry after the node entry donated by PostEntry
  of the doubly linked list.

  @param[in, out]  PostEntry             The entry to insert before.
  @param[in, out]  NewEntry              The new entry to insert.

**/
VOID
EFIAPI
NetListInsertBefore (
  IN OUT LIST_ENTRY  *PostEntry,
  IN OUT LIST_ENTRY  *NewEntry
  )
{
  ASSERT (PostEntry != NULL && NewEntry != NULL);

  NewEntry->ForwardLink            = PostEntry;
  NewEntry->BackLink               = PostEntry->BackLink;
  PostEntry->BackLink->ForwardLink = NewEntry;
  PostEntry->BackLink              = NewEntry;
}

/**
  Safe destroy nodes in a linked list, and return the length of the list after all possible operations finished.

  Destroy network child instance list by list traversals is not safe due to graph dependencies between nodes.
  This function performs a safe traversal to destroy these nodes by checking to see if the node being destroyed
  has been removed from the list or not.
  If it has been removed, then restart the traversal from the head.
  If it hasn't been removed, then continue with the next node directly.
  This function will end the iterate and return the CallBack's last return value if error happens,
  or return EFI_SUCCESS if 2 complete passes are made with no changes in the number of children in the list.

  @param[in]    List             The head of the list.
  @param[in]    CallBack         Pointer to the callback function to destroy one node in the list.
  @param[in]    Context          Pointer to the callback function's context: corresponds to the
                                 parameter Context in NET_DESTROY_LINK_LIST_CALLBACK.
  @param[out]   ListLength       The length of the link list if the function returns successfully.

  @retval EFI_SUCCESS            Two complete passes are made with no changes in the number of children.
  @retval EFI_INVALID_PARAMETER  The input parameter is invalid.
  @retval Others                 Return the CallBack's last return value.

**/
EFI_STATUS
EFIAPI
NetDestroyLinkList (
  IN   LIST_ENTRY                      *List,
  IN   NET_DESTROY_LINK_LIST_CALLBACK  CallBack,
  IN   VOID                            *Context     OPTIONAL,
  OUT  UINTN                           *ListLength  OPTIONAL
  )
{
  UINTN       PreviousLength;
  LIST_ENTRY  *Entry;
  LIST_ENTRY  *Ptr;
  UINTN       Length;
  EFI_STATUS  Status;

  if ((List == NULL) || (CallBack == NULL)) {
    return EFI_INVALID_PARAMETER;
  }

  Length = 0;
  do {
    PreviousLength = Length;
    Entry          = GetFirstNode (List);
    while (!IsNull (List, Entry)) {
      Status = CallBack (Entry, Context);
      if (EFI_ERROR (Status)) {
        return Status;
      }

      //
      // Walk through the list to see whether the Entry has been removed or not.
      // If the Entry still exists, just try to destroy the next one.
      // If not, go back to the start point to iterate the list again.
      //
      for (Ptr = List->ForwardLink; Ptr != List; Ptr = Ptr->ForwardLink) {
        if (Ptr == Entry) {
          break;
        }
      }

      if (Ptr == Entry) {
        Entry = GetNextNode (List, Entry);
      } else {
        Entry = GetFirstNode (List);
      }
    }

    for (Length = 0, Ptr = List->ForwardLink; Ptr != List; Length++, Ptr = Ptr->ForwardLink) {
    }
  } while (Length != PreviousLength);

  if (ListLength != NULL) {
    *ListLength = Length;
  }

  return EFI_SUCCESS;
}

/**
  This function checks the input Handle to see if it's one of these handles in ChildHandleBuffer.

  @param[in]  Handle             Handle to be checked.
  @param[in]  NumberOfChildren   Number of Handles in ChildHandleBuffer.
  @param[in]  ChildHandleBuffer  An array of child handles to be freed. May be NULL
                                 if NumberOfChildren is 0.

  @retval TRUE                   Found the input Handle in ChildHandleBuffer.
  @retval FALSE                  Can't find the input Handle in ChildHandleBuffer.

**/
BOOLEAN
EFIAPI
NetIsInHandleBuffer (
  IN  EFI_HANDLE  Handle,
  IN  UINTN       NumberOfChildren,
  IN  EFI_HANDLE  *ChildHandleBuffer OPTIONAL
  )
{
  UINTN  Index;

  if ((NumberOfChildren == 0) || (ChildHandleBuffer == NULL)) {
    return FALSE;
  }

  for (Index = 0; Index < NumberOfChildren; Index++) {
    if (Handle == ChildHandleBuffer[Index]) {
      return TRUE;
    }
  }

  return FALSE;
}

/**
  Initialize the netmap. Netmap is a reposity to keep the <Key, Value> pairs.

  Initialize the forward and backward links of two head nodes donated by Map->Used
  and Map->Recycled of two doubly linked lists.
  Initializes the count of the <Key, Value> pairs in the netmap to zero.

  If Map is NULL, then ASSERT().
  If the address of Map->Used is NULL, then ASSERT().
  If the address of Map->Recycled is NULl, then ASSERT().

  @param[in, out]  Map                   The netmap to initialize.

**/
VOID
EFIAPI
NetMapInit (
  IN OUT NET_MAP  *Map
  )
{
  ASSERT (Map != NULL);

  InitializeListHead (&Map->Used);
  InitializeListHead (&Map->Recycled);
  Map->Count = 0;
}

/**
  To clean up the netmap, that is, release allocated memories.

  Removes all nodes of the Used doubly linked list and free memory of all related netmap items.
  Removes all nodes of the Recycled doubly linked list and free memory of all related netmap items.
  The number of the <Key, Value> pairs in the netmap is set to be zero.

  If Map is NULL, then ASSERT().

  @param[in, out]  Map                   The netmap to clean up.

**/
VOID
EFIAPI
NetMapClean (
  IN OUT NET_MAP  *Map
  )
{
  NET_MAP_ITEM  *Item;
  LIST_ENTRY    *Entry;
  LIST_ENTRY    *Next;

  ASSERT (Map != NULL);

  NET_LIST_FOR_EACH_SAFE (Entry, Next, &Map->Used) {
    Item = NET_LIST_USER_STRUCT (Entry, NET_MAP_ITEM, Link);

    RemoveEntryList (&Item->Link);
    Map->Count--;

    gBS->FreePool (Item);
  }

  ASSERT ((Map->Count == 0) && IsListEmpty (&Map->Used));

  NET_LIST_FOR_EACH_SAFE (Entry, Next, &Map->Recycled) {
    Item = NET_LIST_USER_STRUCT (Entry, NET_MAP_ITEM, Link);

    RemoveEntryList (&Item->Link);
    gBS->FreePool (Item);
  }

  ASSERT (IsListEmpty (&Map->Recycled));
}

/**
  Test whether the netmap is empty and return true if it is.

  If the number of the <Key, Value> pairs in the netmap is zero, return TRUE.

  If Map is NULL, then ASSERT().

  @param[in]  Map                   The net map to test.

  @return TRUE if the netmap is empty, otherwise FALSE.

**/
BOOLEAN
EFIAPI
NetMapIsEmpty (
  IN NET_MAP  *Map
  )
{
  ASSERT (Map != NULL);
  return (BOOLEAN)(Map->Count == 0);
}

/**
  Return the number of the <Key, Value> pairs in the netmap.

  If Map is NULL, then ASSERT().

  @param[in]  Map                   The netmap to get the entry number.

  @return The entry number in the netmap.

**/
UINTN
EFIAPI
NetMapGetCount (
  IN NET_MAP  *Map
  )
{
  ASSERT (Map != NULL);
  return Map->Count;
}

/**
  Return one allocated item.

  If the Recycled doubly linked list of the netmap is empty, it will try to allocate
  a batch of items if there are enough resources and add corresponding nodes to the beginning
  of the Recycled doubly linked list of the netmap. Otherwise, it will directly remove
  the fist node entry of the Recycled doubly linked list and return the corresponding item.

  If Map is NULL, then ASSERT().

  @param[in, out]  Map          The netmap to allocate item for.

  @return                       The allocated item. If NULL, the
                                allocation failed due to resource limit.

**/
NET_MAP_ITEM *
NetMapAllocItem (
  IN OUT NET_MAP  *Map
  )
{
  NET_MAP_ITEM  *Item;
  LIST_ENTRY    *Head;
  UINTN         Index;

  ASSERT (Map != NULL);

  Head = &Map->Recycled;

  if (IsListEmpty (Head)) {
    for (Index = 0; Index < NET_MAP_INCREAMENT; Index++) {
      Item = AllocatePool (sizeof (NET_MAP_ITEM));

      if (Item == NULL) {
        if (Index == 0) {
          return NULL;
        }

        break;
      }

      InsertHeadList (Head, &Item->Link);
    }
  }

  Item = NET_LIST_HEAD (Head, NET_MAP_ITEM, Link);
  NetListRemoveHead (Head);

  return Item;
}

/**
  Allocate an item to save the <Key, Value> pair to the head of the netmap.

  Allocate an item to save the <Key, Value> pair and add corresponding node entry
  to the beginning of the Used doubly linked list. The number of the <Key, Value>
  pairs in the netmap increase by 1.

  If Map is NULL, then ASSERT().
  If Key is NULL, then ASSERT().

  @param[in, out]  Map                   The netmap to insert into.
  @param[in]       Key                   The user's key.
  @param[in]       Value                 The user's value for the key.

  @retval EFI_OUT_OF_RESOURCES  Failed to allocate the memory for the item.
  @retval EFI_SUCCESS           The item is inserted to the head.

**/
EFI_STATUS
EFIAPI
NetMapInsertHead (
  IN OUT NET_MAP  *Map,
  IN VOID         *Key,
  IN VOID         *Value    OPTIONAL
  )
{
  NET_MAP_ITEM  *Item;

  ASSERT (Map != NULL && Key != NULL);

  Item = NetMapAllocItem (Map);

  if (Item == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  Item->Key   = Key;
  Item->Value = Value;
  InsertHeadList (&Map->Used, &Item->Link);

  Map->Count++;
  return EFI_SUCCESS;
}

/**
  Allocate an item to save the <Key, Value> pair to the tail of the netmap.

  Allocate an item to save the <Key, Value> pair and add corresponding node entry
  to the tail of the Used doubly linked list. The number of the <Key, Value>
  pairs in the netmap increase by 1.

  If Map is NULL, then ASSERT().
  If Key is NULL, then ASSERT().

  @param[in, out]  Map                   The netmap to insert into.
  @param[in]       Key                   The user's key.
  @param[in]       Value                 The user's value for the key.

  @retval EFI_OUT_OF_RESOURCES  Failed to allocate the memory for the item.
  @retval EFI_SUCCESS           The item is inserted to the tail.

**/
EFI_STATUS
EFIAPI
NetMapInsertTail (
  IN OUT NET_MAP  *Map,
  IN VOID         *Key,
  IN VOID         *Value    OPTIONAL
  )
{
  NET_MAP_ITEM  *Item;

  ASSERT (Map != NULL && Key != NULL);

  Item = NetMapAllocItem (Map);

  if (Item == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  Item->Key   = Key;
  Item->Value = Value;
  InsertTailList (&Map->Used, &Item->Link);

  Map->Count++;

  return EFI_SUCCESS;
}

/**
  Check whether the item is in the Map and return TRUE if it is.

  If Map is NULL, then ASSERT().
  If Item is NULL, then ASSERT().

  @param[in]  Map                   The netmap to search within.
  @param[in]  Item                  The item to search.

  @return TRUE if the item is in the netmap, otherwise FALSE.

**/
BOOLEAN
NetItemInMap (
  IN NET_MAP       *Map,
  IN NET_MAP_ITEM  *Item
  )
{
  LIST_ENTRY  *ListEntry;

  ASSERT (Map != NULL && Item != NULL);

  NET_LIST_FOR_EACH (ListEntry, &Map->Used) {
    if (ListEntry == &Item->Link) {
      return TRUE;
    }
  }

  return FALSE;
}

/**
  Find the key in the netmap and returns the point to the item contains the Key.

  Iterate the Used doubly linked list of the netmap to get every item. Compare the key of every
  item with the key to search. It returns the point to the item contains the Key if found.

  If Map is NULL, then ASSERT().
  If Key is NULL, then ASSERT().

  @param[in]  Map                   The netmap to search within.
  @param[in]  Key                   The key to search.

  @return The point to the item contains the Key, or NULL if Key isn't in the map.

**/
NET_MAP_ITEM *
EFIAPI
NetMapFindKey (
  IN  NET_MAP  *Map,
  IN  VOID     *Key
  )
{
  LIST_ENTRY    *Entry;
  NET_MAP_ITEM  *Item;

  ASSERT (Map != NULL && Key != NULL);

  NET_LIST_FOR_EACH (Entry, &Map->Used) {
    Item = NET_LIST_USER_STRUCT (Entry, NET_MAP_ITEM, Link);

    if (Item->Key == Key) {
      return Item;
    }
  }

  return NULL;
}

/**
  Remove the node entry of the item from the netmap and return the key of the removed item.

  Remove the node entry of the item from the Used doubly linked list of the netmap.
  The number of the <Key, Value> pairs in the netmap decrease by 1. Then add the node
  entry of the item to the Recycled doubly linked list of the netmap. If Value is not NULL,
  Value will point to the value of the item. It returns the key of the removed item.

  If Map is NULL, then ASSERT().
  If Item is NULL, then ASSERT().
  if item in not in the netmap, then ASSERT().

  @param[in, out]  Map                   The netmap to remove the item from.
  @param[in, out]  Item                  The item to remove.
  @param[out]      Value                 The variable to receive the value if not NULL.

  @return                                The key of the removed item.

**/
VOID *
EFIAPI
NetMapRemoveItem (
  IN  OUT NET_MAP       *Map,
  IN  OUT NET_MAP_ITEM  *Item,
  OUT VOID              **Value           OPTIONAL
  )
{
  ASSERT ((Map != NULL) && (Item != NULL));
  ASSERT (NetItemInMap (Map, Item));

  RemoveEntryList (&Item->Link);
  Map->Count--;
  InsertHeadList (&Map->Recycled, &Item->Link);

  if (Value != NULL) {
    *Value = Item->Value;
  }

  return Item->Key;
}

/**
  Remove the first node entry on the netmap and return the key of the removed item.

  Remove the first node entry from the Used doubly linked list of the netmap.
  The number of the <Key, Value> pairs in the netmap decrease by 1. Then add the node
  entry to the Recycled doubly linked list of the netmap. If parameter Value is not NULL,
  parameter Value will point to the value of the item. It returns the key of the removed item.

  If Map is NULL, then ASSERT().
  If the Used doubly linked list is empty, then ASSERT().

  @param[in, out]  Map                   The netmap to remove the head from.
  @param[out]      Value                 The variable to receive the value if not NULL.

  @return                                The key of the item removed.

**/
VOID *
EFIAPI
NetMapRemoveHead (
  IN OUT NET_MAP  *Map,
  OUT VOID        **Value         OPTIONAL
  )
{
  NET_MAP_ITEM  *Item;

  //
  // Often, it indicates a programming error to remove
  // the first entry in an empty list
  //
  ASSERT (Map && !IsListEmpty (&Map->Used));

  Item = NET_LIST_HEAD (&Map->Used, NET_MAP_ITEM, Link);
  RemoveEntryList (&Item->Link);
  Map->Count--;
  InsertHeadList (&Map->Recycled, &Item->Link);

  if (Value != NULL) {
    *Value = Item->Value;
  }

  return Item->Key;
}

/**
  Remove the last node entry on the netmap and return the key of the removed item.

  Remove the last node entry from the Used doubly linked list of the netmap.
  The number of the <Key, Value> pairs in the netmap decrease by 1. Then add the node
  entry to the Recycled doubly linked list of the netmap. If parameter Value is not NULL,
  parameter Value will point to the value of the item. It returns the key of the removed item.

  If Map is NULL, then ASSERT().
  If the Used doubly linked list is empty, then ASSERT().

  @param[in, out]  Map                   The netmap to remove the tail from.
  @param[out]      Value                 The variable to receive the value if not NULL.

  @return                                The key of the item removed.

**/
VOID *
EFIAPI
NetMapRemoveTail (
  IN OUT NET_MAP  *Map,
  OUT VOID        **Value       OPTIONAL
  )
{
  NET_MAP_ITEM  *Item;

  //
  // Often, it indicates a programming error to remove
  // the last entry in an empty list
  //
  ASSERT (Map && !IsListEmpty (&Map->Used));

  Item = NET_LIST_TAIL (&Map->Used, NET_MAP_ITEM, Link);
  RemoveEntryList (&Item->Link);
  Map->Count--;
  InsertHeadList (&Map->Recycled, &Item->Link);

  if (Value != NULL) {
    *Value = Item->Value;
  }

  return Item->Key;
}

/**
  Iterate through the netmap and call CallBack for each item.

  It will continue the traverse if CallBack returns EFI_SUCCESS, otherwise, break
  from the loop. It returns the CallBack's last return value. This function is
  delete safe for the current item.

  If Map is NULL, then ASSERT().
  If CallBack is NULL, then ASSERT().

  @param[in]  Map                   The Map to iterate through.
  @param[in]  CallBack              The callback function to call for each item.
  @param[in]  Arg                   The opaque parameter to the callback.

  @retval EFI_SUCCESS            There is no item in the netmap or CallBack for each item
                                 return EFI_SUCCESS.
  @retval Others                 It returns the CallBack's last return value.

**/
EFI_STATUS
EFIAPI
NetMapIterate (
  IN NET_MAP           *Map,
  IN NET_MAP_CALLBACK  CallBack,
  IN VOID              *Arg      OPTIONAL
  )
{
  LIST_ENTRY    *Entry;
  LIST_ENTRY    *Next;
  LIST_ENTRY    *Head;
  NET_MAP_ITEM  *Item;
  EFI_STATUS    Result;

  ASSERT ((Map != NULL) && (CallBack != NULL));

  Head = &Map->Used;

  if (IsListEmpty (Head)) {
    return EFI_SUCCESS;
  }

  NET_LIST_FOR_EACH_SAFE (Entry, Next, Head) {
    Item   = NET_LIST_USER_STRUCT (Entry, NET_MAP_ITEM, Link);
    Result = CallBack (Map, Item, Arg);

    if (EFI_ERROR (Result)) {
      return Result;
    }
  }

  return EFI_SUCCESS;
}

/**
  This is the default unload handle for all the network drivers.

  Disconnect the driver specified by ImageHandle from all the devices in the handle database.
  Uninstall all the protocols installed in the driver entry point.

  @param[in]  ImageHandle       The drivers' driver image.

  @retval EFI_SUCCESS           The image is unloaded.
  @retval Others                Failed to unload the image.

**/
EFI_STATUS
EFIAPI
NetLibDefaultUnload (
  IN EFI_HANDLE  ImageHandle
  )
{
  EFI_STATUS                    Status;
  EFI_HANDLE                    *DeviceHandleBuffer;
  UINTN                         DeviceHandleCount;
  UINTN                         Index;
  UINTN                         Index2;
  EFI_DRIVER_BINDING_PROTOCOL   *DriverBinding;
  EFI_COMPONENT_NAME_PROTOCOL   *ComponentName;
  EFI_COMPONENT_NAME2_PROTOCOL  *ComponentName2;

  //
  // Get the list of all the handles in the handle database.
  // If there is an error getting the list, then the unload
  // operation fails.
  //
  Status = gBS->LocateHandleBuffer (
                  AllHandles,
                  NULL,
                  NULL,
                  &DeviceHandleCount,
                  &DeviceHandleBuffer
                  );

  if (EFI_ERROR (Status)) {
    return Status;
  }

  for (Index = 0; Index < DeviceHandleCount; Index++) {
    Status = gBS->HandleProtocol (
                    DeviceHandleBuffer[Index],
                    &gEfiDriverBindingProtocolGuid,
                    (VOID **)&DriverBinding
                    );
    if (EFI_ERROR (Status)) {
      continue;
    }

    if (DriverBinding->ImageHandle != ImageHandle) {
      continue;
    }

    //
    // Disconnect the driver specified by ImageHandle from all
    // the devices in the handle database.
    //
    for (Index2 = 0; Index2 < DeviceHandleCount; Index2++) {
      Status = gBS->DisconnectController (
                      DeviceHandleBuffer[Index2],
                      DriverBinding->DriverBindingHandle,
                      NULL
                      );
    }

    //
    // Uninstall all the protocols installed in the driver entry point
    //
    gBS->UninstallProtocolInterface (
           DriverBinding->DriverBindingHandle,
           &gEfiDriverBindingProtocolGuid,
           DriverBinding
           );

    Status = gBS->HandleProtocol (
                    DeviceHandleBuffer[Index],
                    &gEfiComponentNameProtocolGuid,
                    (VOID **)&ComponentName
                    );
    if (!EFI_ERROR (Status)) {
      gBS->UninstallProtocolInterface (
             DriverBinding->DriverBindingHandle,
             &gEfiComponentNameProtocolGuid,
             ComponentName
             );
    }

    Status = gBS->HandleProtocol (
                    DeviceHandleBuffer[Index],
                    &gEfiComponentName2ProtocolGuid,
                    (VOID **)&ComponentName2
                    );
    if (!EFI_ERROR (Status)) {
      gBS->UninstallProtocolInterface (
             DriverBinding->DriverBindingHandle,
             &gEfiComponentName2ProtocolGuid,
             ComponentName2
             );
    }
  }

  //
  // Free the buffer containing the list of handles from the handle database
  //
  if (DeviceHandleBuffer != NULL) {
    gBS->FreePool (DeviceHandleBuffer);
  }

  return EFI_SUCCESS;
}

/**
  Create a child of the service that is identified by ServiceBindingGuid.

  Get the ServiceBinding Protocol first, then use it to create a child.

  If ServiceBindingGuid is NULL, then ASSERT().
  If ChildHandle is NULL, then ASSERT().

  @param[in]       Controller            The controller which has the service installed.
  @param[in]       Image                 The image handle used to open service.
  @param[in]       ServiceBindingGuid    The service's Guid.
  @param[in, out]  ChildHandle           The handle to receive the create child.

  @retval EFI_SUCCESS           The child is successfully created.
  @retval Others                Failed to create the child.

**/
EFI_STATUS
EFIAPI
NetLibCreateServiceChild (
  IN  EFI_HANDLE      Controller,
  IN  EFI_HANDLE      Image,
  IN  EFI_GUID        *ServiceBindingGuid,
  IN  OUT EFI_HANDLE  *ChildHandle
  )
{
  EFI_STATUS                    Status;
  EFI_SERVICE_BINDING_PROTOCOL  *Service;

  ASSERT ((ServiceBindingGuid != NULL) && (ChildHandle != NULL));

  //
  // Get the ServiceBinding Protocol
  //
  Status = gBS->OpenProtocol (
                  Controller,
                  ServiceBindingGuid,
                  (VOID **)&Service,
                  Image,
                  Controller,
                  EFI_OPEN_PROTOCOL_GET_PROTOCOL
                  );

  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Create a child
  //
  Status = Service->CreateChild (Service, ChildHandle);
  return Status;
}

/**
  Destroy a child of the service that is identified by ServiceBindingGuid.

  Get the ServiceBinding Protocol first, then use it to destroy a child.

  If ServiceBindingGuid is NULL, then ASSERT().

  @param[in]   Controller            The controller which has the service installed.
  @param[in]   Image                 The image handle used to open service.
  @param[in]   ServiceBindingGuid    The service's Guid.
  @param[in]   ChildHandle           The child to destroy.

  @retval EFI_SUCCESS           The child is successfully destroyed.
  @retval Others                Failed to destroy the child.

**/
EFI_STATUS
EFIAPI
NetLibDestroyServiceChild (
  IN  EFI_HANDLE  Controller,
  IN  EFI_HANDLE  Image,
  IN  EFI_GUID    *ServiceBindingGuid,
  IN  EFI_HANDLE  ChildHandle
  )
{
  EFI_STATUS                    Status;
  EFI_SERVICE_BINDING_PROTOCOL  *Service;

  ASSERT (ServiceBindingGuid != NULL);

  //
  // Get the ServiceBinding Protocol
  //
  Status = gBS->OpenProtocol (
                  Controller,
                  ServiceBindingGuid,
                  (VOID **)&Service,
                  Image,
                  Controller,
                  EFI_OPEN_PROTOCOL_GET_PROTOCOL
                  );

  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // destroy the child
  //
  Status = Service->DestroyChild (Service, ChildHandle);
  return Status;
}

/**
  Get handle with Simple Network Protocol installed on it.

  There should be MNP Service Binding Protocol installed on the input ServiceHandle.
  If Simple Network Protocol is already installed on the ServiceHandle, the
  ServiceHandle will be returned. If SNP is not installed on the ServiceHandle,
  try to find its parent handle with SNP installed.

  @param[in]   ServiceHandle    The handle where network service binding protocols are
                                installed on.
  @param[out]  Snp              The pointer to store the address of the SNP instance.
                                This is an optional parameter that may be NULL.

  @return The SNP handle, or NULL if not found.

**/
EFI_HANDLE
EFIAPI
NetLibGetSnpHandle (
  IN   EFI_HANDLE                   ServiceHandle,
  OUT  EFI_SIMPLE_NETWORK_PROTOCOL  **Snp  OPTIONAL
  )
{
  EFI_STATUS                   Status;
  EFI_SIMPLE_NETWORK_PROTOCOL  *SnpInstance;
  EFI_DEVICE_PATH_PROTOCOL     *DevicePath;
  EFI_HANDLE                   SnpHandle;

  //
  // Try to open SNP from ServiceHandle
  //
  SnpInstance = NULL;
  Status      = gBS->HandleProtocol (ServiceHandle, &gEfiSimpleNetworkProtocolGuid, (VOID **)&SnpInstance);
  if (!EFI_ERROR (Status)) {
    if (Snp != NULL) {
      *Snp = SnpInstance;
    }

    return ServiceHandle;
  }

  //
  // Failed to open SNP, try to get SNP handle by LocateDevicePath()
  //
  DevicePath = DevicePathFromHandle (ServiceHandle);
  if (DevicePath == NULL) {
    return NULL;
  }

  SnpHandle = NULL;
  Status    = gBS->LocateDevicePath (&gEfiSimpleNetworkProtocolGuid, &DevicePath, &SnpHandle);
  if (EFI_ERROR (Status)) {
    //
    // Failed to find SNP handle
    //
    return NULL;
  }

  Status = gBS->HandleProtocol (SnpHandle, &gEfiSimpleNetworkProtocolGuid, (VOID **)&SnpInstance);
  if (!EFI_ERROR (Status)) {
    if (Snp != NULL) {
      *Snp = SnpInstance;
    }

    return SnpHandle;
  }

  return NULL;
}

/**
  Retrieve VLAN ID of a VLAN device handle.

  Search VLAN device path node in Device Path of specified ServiceHandle and
  return its VLAN ID. If no VLAN device path node found, then this ServiceHandle
  is not a VLAN device handle, and 0 will be returned.

  @param[in]   ServiceHandle    The handle where network service binding protocols are
                                installed on.

  @return VLAN ID of the device handle, or 0 if not a VLAN device.

**/
UINT16
EFIAPI
NetLibGetVlanId (
  IN EFI_HANDLE  ServiceHandle
  )
{
  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
  EFI_DEVICE_PATH_PROTOCOL  *Node;

  DevicePath = DevicePathFromHandle (ServiceHandle);
  if (DevicePath == NULL) {
    return 0;
  }

  Node = DevicePath;
  while (!IsDevicePathEnd (Node)) {
    if ((Node->Type == MESSAGING_DEVICE_PATH) && (Node->SubType == MSG_VLAN_DP)) {
      return ((VLAN_DEVICE_PATH *)Node)->VlanId;
    }

    Node = NextDevicePathNode (Node);
  }

  return 0;
}

/**
  Find VLAN device handle with specified VLAN ID.

  The VLAN child device handle is created by VLAN Config Protocol on ControllerHandle.
  This function will append VLAN device path node to the parent device path,
  and then use LocateDevicePath() to find the correct VLAN device handle.

  @param[in]   ControllerHandle The handle where network service binding protocols are
                                installed on.
  @param[in]   VlanId           The configured VLAN ID for the VLAN device.

  @return The VLAN device handle, or NULL if not found.

**/
EFI_HANDLE
EFIAPI
NetLibGetVlanHandle (
  IN EFI_HANDLE  ControllerHandle,
  IN UINT16      VlanId
  )
{
  EFI_DEVICE_PATH_PROTOCOL  *ParentDevicePath;
  EFI_DEVICE_PATH_PROTOCOL  *VlanDevicePath;
  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
  VLAN_DEVICE_PATH          VlanNode;
  EFI_HANDLE                Handle;

  ParentDevicePath = DevicePathFromHandle (ControllerHandle);
  if (ParentDevicePath == NULL) {
    return NULL;
  }

  //
  // Construct VLAN device path
  //
  CopyMem (&VlanNode, &mNetVlanDevicePathTemplate, sizeof (VLAN_DEVICE_PATH));
  VlanNode.VlanId = VlanId;
  VlanDevicePath  = AppendDevicePathNode (
                      ParentDevicePath,
                      (EFI_DEVICE_PATH_PROTOCOL *)&VlanNode
                      );
  if (VlanDevicePath == NULL) {
    return NULL;
  }

  //
  // Find VLAN device handle
  //
  Handle     = NULL;
  DevicePath = VlanDevicePath;
  gBS->LocateDevicePath (
         &gEfiDevicePathProtocolGuid,
         &DevicePath,
         &Handle
         );
  if (!IsDevicePathEnd (DevicePath)) {
    //
    // Device path is not exactly match
    //
    Handle = NULL;
  }

  FreePool (VlanDevicePath);
  return Handle;
}

/**
  Get MAC address associated with the network service handle.

  If MacAddress is NULL, then ASSERT().
  If AddressSize is NULL, then ASSERT().

  There should be MNP Service Binding Protocol installed on the input ServiceHandle.
  If SNP is installed on the ServiceHandle or its parent handle, MAC address will
  be retrieved from SNP. If no SNP found, try to get SNP mode data use MNP.

  @param[in]   ServiceHandle    The handle where network service binding protocols are
                                installed on.
  @param[out]  MacAddress       The pointer to store the returned MAC address.
  @param[out]  AddressSize      The length of returned MAC address.

  @retval EFI_SUCCESS           MAC address is returned successfully.
  @retval Others                Failed to get SNP mode data.

**/
EFI_STATUS
EFIAPI
NetLibGetMacAddress (
  IN  EFI_HANDLE       ServiceHandle,
  OUT EFI_MAC_ADDRESS  *MacAddress,
  OUT UINTN            *AddressSize
  )
{
  EFI_STATUS                    Status;
  EFI_SIMPLE_NETWORK_PROTOCOL   *Snp;
  EFI_SIMPLE_NETWORK_MODE       *SnpMode;
  EFI_SIMPLE_NETWORK_MODE       SnpModeData;
  EFI_MANAGED_NETWORK_PROTOCOL  *Mnp;
  EFI_SERVICE_BINDING_PROTOCOL  *MnpSb;
  EFI_HANDLE                    SnpHandle;
  EFI_HANDLE                    MnpChildHandle;

  ASSERT (MacAddress != NULL);
  ASSERT (AddressSize != NULL);

  //
  // Try to get SNP handle
  //
  Snp       = NULL;
  SnpHandle = NetLibGetSnpHandle (ServiceHandle, &Snp);
  if (SnpHandle != NULL) {
    //
    // SNP found, use it directly
    //
    SnpMode = Snp->Mode;
  } else {
    //
    // Failed to get SNP handle, try to get MAC address from MNP
    //
    MnpChildHandle = NULL;
    Status         = gBS->HandleProtocol (
                            ServiceHandle,
                            &gEfiManagedNetworkServiceBindingProtocolGuid,
                            (VOID **)&MnpSb
                            );
    if (EFI_ERROR (Status)) {
      return Status;
    }

    //
    // Create a MNP child
    //
    Status = MnpSb->CreateChild (MnpSb, &MnpChildHandle);
    if (EFI_ERROR (Status)) {
      return Status;
    }

    //
    // Open MNP protocol
    //
    Status = gBS->HandleProtocol (
                    MnpChildHandle,
                    &gEfiManagedNetworkProtocolGuid,
                    (VOID **)&Mnp
                    );
    if (EFI_ERROR (Status)) {
      MnpSb->DestroyChild (MnpSb, MnpChildHandle);
      return Status;
    }

    //
    // Try to get SNP mode from MNP
    //
    Status = Mnp->GetModeData (Mnp, NULL, &SnpModeData);
    if (EFI_ERROR (Status) && (Status != EFI_NOT_STARTED)) {
      MnpSb->DestroyChild (MnpSb, MnpChildHandle);
      return Status;
    }

    SnpMode = &SnpModeData;

    //
    // Destroy the MNP child
    //
    MnpSb->DestroyChild (MnpSb, MnpChildHandle);
  }

  *AddressSize = SnpMode->HwAddressSize;
  CopyMem (MacAddress->Addr, SnpMode->CurrentAddress.Addr, SnpMode->HwAddressSize);

  return EFI_SUCCESS;
}

/**
  Convert MAC address of the NIC associated with specified Service Binding Handle
  to a unicode string. Callers are responsible for freeing the string storage.

  If MacString is NULL, then ASSERT().

  Locate simple network protocol associated with the Service Binding Handle and
  get the mac address from SNP. Then convert the mac address into a unicode
  string. It takes 2 unicode characters to represent a 1 byte binary buffer.
  Plus one unicode character for the null-terminator.

  @param[in]   ServiceHandle         The handle where network service binding protocol is
                                     installed on.
  @param[in]   ImageHandle           The image handle used to act as the agent handle to
                                     get the simple network protocol. This parameter is
                                     optional and may be NULL.
  @param[out]  MacString             The pointer to store the address of the string
                                     representation of  the mac address.

  @retval EFI_SUCCESS           Convert the mac address a unicode string successfully.
  @retval EFI_OUT_OF_RESOURCES  There are not enough memory resource.
  @retval Others                Failed to open the simple network protocol.

**/
EFI_STATUS
EFIAPI
NetLibGetMacString (
  IN  EFI_HANDLE  ServiceHandle,
  IN  EFI_HANDLE  ImageHandle  OPTIONAL,
  OUT CHAR16      **MacString
  )
{
  EFI_STATUS       Status;
  EFI_MAC_ADDRESS  MacAddress;
  UINT8            *HwAddress;
  UINTN            HwAddressSize;
  UINT16           VlanId;
  CHAR16           *String;
  UINTN            Index;
  UINTN            BufferSize;

  ASSERT (MacString != NULL);

  //
  // Get MAC address of the network device
  //
  Status = NetLibGetMacAddress (ServiceHandle, &MacAddress, &HwAddressSize);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // It takes 2 unicode characters to represent a 1 byte binary buffer.
  // If VLAN is configured, it will need extra 5 characters like "\0005".
  // Plus one unicode character for the null-terminator.
  //
  BufferSize = (2 * HwAddressSize + 5 + 1) * sizeof (CHAR16);
  String     = AllocateZeroPool (BufferSize);
  if (String == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  *MacString = String;

  //
  // Convert the MAC address into a unicode string.
  //
  HwAddress = &MacAddress.Addr[0];
  for (Index = 0; Index < HwAddressSize; Index++) {
    UnicodeValueToStringS (
      String,
      BufferSize - ((UINTN)String - (UINTN)*MacString),
      PREFIX_ZERO | RADIX_HEX,
      *(HwAddress++),
      2
      );
    String += StrnLenS (String, (BufferSize - ((UINTN)String - (UINTN)*MacString)) / sizeof (CHAR16));
  }

  //
  // Append VLAN ID if any
  //
  VlanId = NetLibGetVlanId (ServiceHandle);
  if (VlanId != 0) {
    *String++ = L'\\';
    UnicodeValueToStringS (
      String,
      BufferSize - ((UINTN)String - (UINTN)*MacString),
      PREFIX_ZERO | RADIX_HEX,
      VlanId,
      4
      );
    String += StrnLenS (String, (BufferSize - ((UINTN)String - (UINTN)*MacString)) / sizeof (CHAR16));
  }

  //
  // Null terminate the Unicode string
  //
  *String = L'\0';

  return EFI_SUCCESS;
}

/**
  Detect media status for specified network device.

  If MediaPresent is NULL, then ASSERT().

  The underlying UNDI driver may or may not support reporting media status from
  GET_STATUS command (PXE_STATFLAGS_GET_STATUS_NO_MEDIA_SUPPORTED). This routine
  will try to invoke Snp->GetStatus() to get the media status: if media already
  present, it return directly; if media not present, it will stop SNP and then
  restart SNP to get the latest media status, this give chance to get the correct
  media status for old UNDI driver which doesn't support reporting media status
  from GET_STATUS command.
  Note: there will be two limitations for current algorithm:
  1) for UNDI with this capability, in case of cable is not attached, there will
     be an redundant Stop/Start() process;
  2) for UNDI without this capability, in case that network cable is attached when
     Snp->Initialize() is invoked while network cable is unattached later,
     NetLibDetectMedia() will report MediaPresent as TRUE, causing upper layer
     apps to wait for timeout time.

  @param[in]   ServiceHandle    The handle where network service binding protocols are
                                installed on.
  @param[out]  MediaPresent     The pointer to store the media status.

  @retval EFI_SUCCESS           Media detection success.
  @retval EFI_INVALID_PARAMETER ServiceHandle is not valid network device handle.
  @retval EFI_UNSUPPORTED       Network device does not support media detection.
  @retval EFI_DEVICE_ERROR      SNP is in unknown state.

**/
EFI_STATUS
EFIAPI
NetLibDetectMedia (
  IN  EFI_HANDLE  ServiceHandle,
  OUT BOOLEAN     *MediaPresent
  )
{
  EFI_STATUS                   Status;
  EFI_HANDLE                   SnpHandle;
  EFI_SIMPLE_NETWORK_PROTOCOL  *Snp;
  UINT32                       InterruptStatus;
  UINT32                       OldState;
  EFI_MAC_ADDRESS              *MCastFilter;
  UINT32                       MCastFilterCount;
  UINT32                       EnableFilterBits;
  UINT32                       DisableFilterBits;
  BOOLEAN                      ResetMCastFilters;

  ASSERT (MediaPresent != NULL);

  //
  // Get SNP handle
  //
  Snp       = NULL;
  SnpHandle = NetLibGetSnpHandle (ServiceHandle, &Snp);
  if (SnpHandle == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Check whether SNP support media detection
  //
  if (!Snp->Mode->MediaPresentSupported) {
    return EFI_UNSUPPORTED;
  }

  //
  // Invoke Snp->GetStatus() to refresh MediaPresent field in SNP mode data
  //
  Status = Snp->GetStatus (Snp, &InterruptStatus, NULL);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  if (Snp->Mode->MediaPresent) {
    //
    // Media is present, return directly
    //
    *MediaPresent = TRUE;
    return EFI_SUCCESS;
  }

  //
  // Till now, GetStatus() report no media; while, in case UNDI not support
  // reporting media status from GetStatus(), this media status may be incorrect.
  // So, we will stop SNP and then restart it to get the correct media status.
  //
  OldState = Snp->Mode->State;
  if (OldState >= EfiSimpleNetworkMaxState) {
    return EFI_DEVICE_ERROR;
  }

  MCastFilter = NULL;

  if (OldState == EfiSimpleNetworkInitialized) {
    //
    // SNP is already in use, need Shutdown/Stop and then Start/Initialize
    //

    //
    // Backup current SNP receive filter settings
    //
    EnableFilterBits  = Snp->Mode->ReceiveFilterSetting;
    DisableFilterBits = Snp->Mode->ReceiveFilterMask ^ EnableFilterBits;

    ResetMCastFilters = TRUE;
    MCastFilterCount  = Snp->Mode->MCastFilterCount;
    if (MCastFilterCount != 0) {
      MCastFilter = AllocateCopyPool (
                      MCastFilterCount * sizeof (EFI_MAC_ADDRESS),
                      Snp->Mode->MCastFilter
                      );
      ASSERT (MCastFilter != NULL);
      if (MCastFilter == NULL) {
        Status = EFI_OUT_OF_RESOURCES;
        goto Exit;
      }

      ResetMCastFilters = FALSE;
    }

    //
    // Shutdown/Stop the simple network
    //
    Status = Snp->Shutdown (Snp);
    if (!EFI_ERROR (Status)) {
      Status = Snp->Stop (Snp);
    }

    if (EFI_ERROR (Status)) {
      goto Exit;
    }

    //
    // Start/Initialize the simple network
    //
    Status = Snp->Start (Snp);
    if (!EFI_ERROR (Status)) {
      Status = Snp->Initialize (Snp, 0, 0);
    }

    if (EFI_ERROR (Status)) {
      goto Exit;
    }

    //
    // Here we get the correct media status
    //
    *MediaPresent = Snp->Mode->MediaPresent;

    //
    // Restore SNP receive filter settings
    //
    Status = Snp->ReceiveFilters (
                    Snp,
                    EnableFilterBits,
                    DisableFilterBits,
                    ResetMCastFilters,
                    MCastFilterCount,
                    MCastFilter
                    );

    if (MCastFilter != NULL) {
      FreePool (MCastFilter);
    }

    return Status;
  }

  //
  // SNP is not in use, it's in state of EfiSimpleNetworkStopped or EfiSimpleNetworkStarted
  //
  if (OldState == EfiSimpleNetworkStopped) {
    //
    // SNP not start yet, start it
    //
    Status = Snp->Start (Snp);
    if (EFI_ERROR (Status)) {
      goto Exit;
    }
  }

  //
  // Initialize the simple network
  //
  Status = Snp->Initialize (Snp, 0, 0);
  if (EFI_ERROR (Status)) {
    Status = EFI_DEVICE_ERROR;
    goto Exit;
  }

  //
  // Here we get the correct media status
  //
  *MediaPresent = Snp->Mode->MediaPresent;

  //
  // Shut down the simple network
  //
  Snp->Shutdown (Snp);

Exit:
  if (OldState == EfiSimpleNetworkStopped) {
    //
    // Original SNP sate is Stopped, restore to original state
    //
    Snp->Stop (Snp);
  }

  if (MCastFilter != NULL) {
    FreePool (MCastFilter);
  }

  return Status;
}

/**

  Detect media state for a network device. This routine will wait for a period of time at
  a specified checking interval when a certain network is under connecting until connection
  process finishs or timeout. If Aip protocol is supported by low layer drivers, three kinds
  of media states can be detected: EFI_SUCCESS, EFI_NOT_READY and EFI_NO_MEDIA, represents
  connected state, connecting state and no media state respectively. When function detects
  the current state is EFI_NOT_READY, it will loop to wait for next time's check until state
  turns to be EFI_SUCCESS or EFI_NO_MEDIA. If Aip protocol is not supported, function will
  call NetLibDetectMedia() and return state directly.

  @param[in]   ServiceHandle    The handle where network service binding protocols are
                                installed on.
  @param[in]   Timeout          The maximum number of 100ns units to wait when network
                                is connecting. Zero value means detect once and return
                                immediately.
  @param[out]  MediaState       The pointer to the detected media state.

  @retval EFI_SUCCESS           Media detection success.
  @retval EFI_INVALID_PARAMETER ServiceHandle is not a valid network device handle or
                                MediaState pointer is NULL.
  @retval EFI_DEVICE_ERROR      A device error occurred.
  @retval EFI_TIMEOUT           Network is connecting but timeout.

**/
EFI_STATUS
EFIAPI
NetLibDetectMediaWaitTimeout (
  IN  EFI_HANDLE  ServiceHandle,
  IN  UINT64      Timeout,
  OUT EFI_STATUS  *MediaState
  )
{
  EFI_STATUS                        Status;
  EFI_HANDLE                        SnpHandle;
  EFI_SIMPLE_NETWORK_PROTOCOL       *Snp;
  EFI_ADAPTER_INFORMATION_PROTOCOL  *Aip;
  EFI_ADAPTER_INFO_MEDIA_STATE      *MediaInfo;
  BOOLEAN                           MediaPresent;
  UINTN                             DataSize;
  EFI_STATUS                        TimerStatus;
  EFI_EVENT                         Timer;
  UINT64                            TimeRemained;

  if (MediaState == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  *MediaState = EFI_SUCCESS;
  MediaInfo   = NULL;

  //
  // Get SNP handle
  //
  Snp       = NULL;
  SnpHandle = NetLibGetSnpHandle (ServiceHandle, &Snp);
  if (SnpHandle == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Status = gBS->HandleProtocol (
                  SnpHandle,
                  &gEfiAdapterInformationProtocolGuid,
                  (VOID *)&Aip
                  );
  if (EFI_ERROR (Status)) {
    MediaPresent = TRUE;
    Status       = NetLibDetectMedia (ServiceHandle, &MediaPresent);
    if (!EFI_ERROR (Status)) {
      if (MediaPresent) {
        *MediaState = EFI_SUCCESS;
      } else {
        *MediaState = EFI_NO_MEDIA;
      }
    }

    //
    // NetLibDetectMedia doesn't support EFI_NOT_READY status, return now!
    //
    return Status;
  }

  Status = Aip->GetInformation (
                  Aip,
                  &gEfiAdapterInfoMediaStateGuid,
                  (VOID **)&MediaInfo,
                  &DataSize
                  );
  if (!EFI_ERROR (Status)) {
    *MediaState = MediaInfo->MediaState;
    FreePool (MediaInfo);
    if ((*MediaState != EFI_NOT_READY) || (Timeout < MEDIA_STATE_DETECT_TIME_INTERVAL)) {
      return EFI_SUCCESS;
    }
  } else {
    if (MediaInfo != NULL) {
      FreePool (MediaInfo);
    }

    if (Status == EFI_UNSUPPORTED) {
      //
      // If gEfiAdapterInfoMediaStateGuid is not supported, call NetLibDetectMedia to get media state!
      //
      MediaPresent = TRUE;
      Status       = NetLibDetectMedia (ServiceHandle, &MediaPresent);
      if (!EFI_ERROR (Status)) {
        if (MediaPresent) {
          *MediaState = EFI_SUCCESS;
        } else {
          *MediaState = EFI_NO_MEDIA;
        }
      }

      return Status;
    }

    return Status;
  }

  //
  // Loop to check media state
  //

  Timer        = NULL;
  TimeRemained = Timeout;
  Status       = gBS->CreateEvent (EVT_TIMER, TPL_CALLBACK, NULL, NULL, &Timer);
  if (EFI_ERROR (Status)) {
    return EFI_DEVICE_ERROR;
  }

  do {
    Status = gBS->SetTimer (
                    Timer,
                    TimerRelative,
                    MEDIA_STATE_DETECT_TIME_INTERVAL
                    );
    if (EFI_ERROR (Status)) {
      gBS->CloseEvent (Timer);
      return EFI_DEVICE_ERROR;
    }

    do {
      TimerStatus = gBS->CheckEvent (Timer);
      if (!EFI_ERROR (TimerStatus)) {
        TimeRemained -= MEDIA_STATE_DETECT_TIME_INTERVAL;
        Status        = Aip->GetInformation (
                               Aip,
                               &gEfiAdapterInfoMediaStateGuid,
                               (VOID **)&MediaInfo,
                               &DataSize
                               );
        if (!EFI_ERROR (Status)) {
          *MediaState = MediaInfo->MediaState;
          FreePool (MediaInfo);
        } else {
          if (MediaInfo != NULL) {
            FreePool (MediaInfo);
          }

          gBS->CloseEvent (Timer);
          return Status;
        }
      }
    } while (TimerStatus == EFI_NOT_READY);
  } while (*MediaState == EFI_NOT_READY && TimeRemained >= MEDIA_STATE_DETECT_TIME_INTERVAL);

  gBS->CloseEvent (Timer);
  if ((*MediaState == EFI_NOT_READY) && (TimeRemained < MEDIA_STATE_DETECT_TIME_INTERVAL)) {
    return EFI_TIMEOUT;
  } else {
    return EFI_SUCCESS;
  }
}

/**
  Check the default address used by the IPv4 driver is static or dynamic (acquired
  from DHCP).

  If the controller handle does not have the EFI_IP4_CONFIG2_PROTOCOL installed, the
  default address is static. If failed to get the policy from Ip4 Config2 Protocol,
  the default address is static. Otherwise, get the result from Ip4 Config2 Protocol.

  @param[in]   Controller     The controller handle which has the EFI_IP4_CONFIG2_PROTOCOL
                              relative with the default address to judge.

  @retval TRUE           If the default address is static.
  @retval FALSE          If the default address is acquired from DHCP.

**/
BOOLEAN
NetLibDefaultAddressIsStatic (
  IN EFI_HANDLE  Controller
  )
{
  EFI_STATUS                Status;
  EFI_IP4_CONFIG2_PROTOCOL  *Ip4Config2;
  UINTN                     DataSize;
  EFI_IP4_CONFIG2_POLICY    Policy;
  BOOLEAN                   IsStatic;

  Ip4Config2 = NULL;

  DataSize = sizeof (EFI_IP4_CONFIG2_POLICY);

  IsStatic = TRUE;

  //
  // Get Ip4Config2 policy.
  //
  Status = gBS->HandleProtocol (Controller, &gEfiIp4Config2ProtocolGuid, (VOID **)&Ip4Config2);
  if (EFI_ERROR (Status)) {
    goto ON_EXIT;
  }

  Status = Ip4Config2->GetData (Ip4Config2, Ip4Config2DataTypePolicy, &DataSize, &Policy);
  if (EFI_ERROR (Status)) {
    goto ON_EXIT;
  }

  IsStatic = (BOOLEAN)(Policy == Ip4Config2PolicyStatic);

ON_EXIT:

  return IsStatic;
}

/**
  Create an IPv4 device path node.

  If Node is NULL, then ASSERT().

  The header type of IPv4 device path node is MESSAGING_DEVICE_PATH.
  The header subtype of IPv4 device path node is MSG_IPv4_DP.
  Get other info from parameters to make up the whole IPv4 device path node.

  @param[in, out]  Node                  Pointer to the IPv4 device path node.
  @param[in]       Controller            The controller handle.
  @param[in]       LocalIp               The local IPv4 address.
  @param[in]       LocalPort             The local port.
  @param[in]       RemoteIp              The remote IPv4 address.
  @param[in]       RemotePort            The remote port.
  @param[in]       Protocol              The protocol type in the IP header.
  @param[in]       UseDefaultAddress     Whether this instance is using default address or not.

**/
VOID
EFIAPI
NetLibCreateIPv4DPathNode (
  IN OUT IPv4_DEVICE_PATH  *Node,
  IN EFI_HANDLE            Controller,
  IN IP4_ADDR              LocalIp,
  IN UINT16                LocalPort,
  IN IP4_ADDR              RemoteIp,
  IN UINT16                RemotePort,
  IN UINT16                Protocol,
  IN BOOLEAN               UseDefaultAddress
  )
{
  ASSERT (Node != NULL);

  Node->Header.Type    = MESSAGING_DEVICE_PATH;
  Node->Header.SubType = MSG_IPv4_DP;
  SetDevicePathNodeLength (&Node->Header, sizeof (IPv4_DEVICE_PATH));

  CopyMem (&Node->LocalIpAddress, &LocalIp, sizeof (EFI_IPv4_ADDRESS));
  CopyMem (&Node->RemoteIpAddress, &RemoteIp, sizeof (EFI_IPv4_ADDRESS));

  Node->LocalPort  = LocalPort;
  Node->RemotePort = RemotePort;

  Node->Protocol = Protocol;

  if (!UseDefaultAddress) {
    Node->StaticIpAddress = TRUE;
  } else {
    Node->StaticIpAddress = NetLibDefaultAddressIsStatic (Controller);
  }

  //
  // Set the Gateway IP address to default value 0:0:0:0.
  // Set the Subnet mask to default value 255:255:255:0.
  //
  ZeroMem (&Node->GatewayIpAddress, sizeof (EFI_IPv4_ADDRESS));
  SetMem (&Node->SubnetMask, sizeof (EFI_IPv4_ADDRESS), 0xff);
  Node->SubnetMask.Addr[3] = 0;
}

/**
  Create an IPv6 device path node.

  If Node is NULL, then ASSERT().
  If LocalIp is NULL, then ASSERT().
  If RemoteIp is NULL, then ASSERT().

  The header type of IPv6 device path node is MESSAGING_DEVICE_PATH.
  The header subtype of IPv6 device path node is MSG_IPv6_DP.
  Get other info from parameters to make up the whole IPv6 device path node.

  @param[in, out]  Node                  Pointer to the IPv6 device path node.
  @param[in]       Controller            The controller handle.
  @param[in]       LocalIp               The local IPv6 address.
  @param[in]       LocalPort             The local port.
  @param[in]       RemoteIp              The remote IPv6 address.
  @param[in]       RemotePort            The remote port.
  @param[in]       Protocol              The protocol type in the IP header.

**/
VOID
EFIAPI
NetLibCreateIPv6DPathNode (
  IN OUT IPv6_DEVICE_PATH  *Node,
  IN EFI_HANDLE            Controller,
  IN EFI_IPv6_ADDRESS      *LocalIp,
  IN UINT16                LocalPort,
  IN EFI_IPv6_ADDRESS      *RemoteIp,
  IN UINT16                RemotePort,
  IN UINT16                Protocol
  )
{
  ASSERT (Node != NULL && LocalIp != NULL && RemoteIp != NULL);

  Node->Header.Type    = MESSAGING_DEVICE_PATH;
  Node->Header.SubType = MSG_IPv6_DP;
  SetDevicePathNodeLength (&Node->Header, sizeof (IPv6_DEVICE_PATH));

  CopyMem (&Node->LocalIpAddress, LocalIp, sizeof (EFI_IPv6_ADDRESS));
  CopyMem (&Node->RemoteIpAddress, RemoteIp, sizeof (EFI_IPv6_ADDRESS));

  Node->LocalPort  = LocalPort;
  Node->RemotePort = RemotePort;

  Node->Protocol = Protocol;

  //
  // Set default value to IPAddressOrigin, PrefixLength.
  // Set the Gateway IP address to unspecified address.
  //
  Node->IpAddressOrigin = 0;
  Node->PrefixLength    = IP6_PREFIX_LENGTH;
  ZeroMem (&Node->GatewayIpAddress, sizeof (EFI_IPv6_ADDRESS));
}

/**
  Find the UNDI/SNP handle from controller and protocol GUID.

  If ProtocolGuid is NULL, then ASSERT().

  For example, IP will open a MNP child to transmit/receive
  packets, when MNP is stopped, IP should also be stopped. IP
  needs to find its own private data which is related the IP's
  service binding instance that is install on UNDI/SNP handle.
  Now, the controller is either a MNP or ARP child handle. But
  IP opens these handle BY_DRIVER, use that info, we can get the
  UNDI/SNP handle.

  @param[in]  Controller            Then protocol handle to check.
  @param[in]  ProtocolGuid          The protocol that is related with the handle.

  @return The UNDI/SNP handle or NULL for errors.

**/
EFI_HANDLE
EFIAPI
NetLibGetNicHandle (
  IN EFI_HANDLE  Controller,
  IN EFI_GUID    *ProtocolGuid
  )
{
  EFI_OPEN_PROTOCOL_INFORMATION_ENTRY  *OpenBuffer;
  EFI_HANDLE                           Handle;
  EFI_STATUS                           Status;
  UINTN                                OpenCount;
  UINTN                                Index;

  ASSERT (ProtocolGuid != NULL);

  Status = gBS->OpenProtocolInformation (
                  Controller,
                  ProtocolGuid,
                  &OpenBuffer,
                  &OpenCount
                  );

  if (EFI_ERROR (Status)) {
    return NULL;
  }

  Handle = NULL;

  for (Index = 0; Index < OpenCount; Index++) {
    if ((OpenBuffer[Index].Attributes & EFI_OPEN_PROTOCOL_BY_DRIVER) != 0) {
      Handle = OpenBuffer[Index].ControllerHandle;
      break;
    }
  }

  gBS->FreePool (OpenBuffer);
  return Handle;
}

/**
  Convert one Null-terminated ASCII string (decimal dotted) to EFI_IPv4_ADDRESS.

  @param[in]      String         The pointer to the Ascii string.
  @param[out]     Ip4Address     The pointer to the converted IPv4 address.

  @retval EFI_SUCCESS            Convert to IPv4 address successfully.
  @retval EFI_INVALID_PARAMETER  The string is malformatted or Ip4Address is NULL.

**/
EFI_STATUS
EFIAPI
NetLibAsciiStrToIp4 (
  IN CONST CHAR8             *String,
  OUT      EFI_IPv4_ADDRESS  *Ip4Address
  )
{
  RETURN_STATUS  Status;
  CHAR8          *EndPointer;

  Status = AsciiStrToIpv4Address (String, &EndPointer, Ip4Address, NULL);
  if (RETURN_ERROR (Status) || (*EndPointer != '\0')) {
    return EFI_INVALID_PARAMETER;
  } else {
    return EFI_SUCCESS;
  }
}

/**
  Convert one Null-terminated ASCII string to EFI_IPv6_ADDRESS. The format of the
  string is defined in RFC 4291 - Text Representation of Addresses.

  @param[in]      String         The pointer to the Ascii string.
  @param[out]     Ip6Address     The pointer to the converted IPv6 address.

  @retval EFI_SUCCESS            Convert to IPv6 address successfully.
  @retval EFI_INVALID_PARAMETER  The string is malformatted or Ip6Address is NULL.

**/
EFI_STATUS
EFIAPI
NetLibAsciiStrToIp6 (
  IN CONST CHAR8             *String,
  OUT      EFI_IPv6_ADDRESS  *Ip6Address
  )
{
  RETURN_STATUS  Status;
  CHAR8          *EndPointer;

  Status = AsciiStrToIpv6Address (String, &EndPointer, Ip6Address, NULL);
  if (RETURN_ERROR (Status) || (*EndPointer != '\0')) {
    return EFI_INVALID_PARAMETER;
  } else {
    return EFI_SUCCESS;
  }
}

/**
  Convert one Null-terminated Unicode string (decimal dotted) to EFI_IPv4_ADDRESS.

  @param[in]      String         The pointer to the Ascii string.
  @param[out]     Ip4Address     The pointer to the converted IPv4 address.

  @retval EFI_SUCCESS            Convert to IPv4 address successfully.
  @retval EFI_INVALID_PARAMETER  The string is malformatted or Ip4Address is NULL.

**/
EFI_STATUS
EFIAPI
NetLibStrToIp4 (
  IN CONST CHAR16            *String,
  OUT      EFI_IPv4_ADDRESS  *Ip4Address
  )
{
  RETURN_STATUS  Status;
  CHAR16         *EndPointer;

  Status = StrToIpv4Address (String, &EndPointer, Ip4Address, NULL);
  if (RETURN_ERROR (Status) || (*EndPointer != L'\0')) {
    return EFI_INVALID_PARAMETER;
  } else {
    return EFI_SUCCESS;
  }
}

/**
  Convert one Null-terminated Unicode string to EFI_IPv6_ADDRESS.  The format of
  the string is defined in RFC 4291 - Text Representation of Addresses.

  @param[in]      String         The pointer to the Ascii string.
  @param[out]     Ip6Address     The pointer to the converted IPv6 address.

  @retval EFI_SUCCESS            Convert to IPv6 address successfully.
  @retval EFI_INVALID_PARAMETER  The string is malformatted or Ip6Address is NULL.

**/
EFI_STATUS
EFIAPI
NetLibStrToIp6 (
  IN CONST CHAR16            *String,
  OUT      EFI_IPv6_ADDRESS  *Ip6Address
  )
{
  RETURN_STATUS  Status;
  CHAR16         *EndPointer;

  Status = StrToIpv6Address (String, &EndPointer, Ip6Address, NULL);
  if (RETURN_ERROR (Status) || (*EndPointer != L'\0')) {
    return EFI_INVALID_PARAMETER;
  } else {
    return EFI_SUCCESS;
  }
}

/**
  Convert one Null-terminated Unicode string to EFI_IPv6_ADDRESS and prefix length.
  The format of the string is defined in RFC 4291 - Text Representation of Addresses
  Prefixes: ipv6-address/prefix-length.

  @param[in]      String         The pointer to the Ascii string.
  @param[out]     Ip6Address     The pointer to the converted IPv6 address.
  @param[out]     PrefixLength   The pointer to the converted prefix length.

  @retval EFI_SUCCESS            Convert to IPv6 address successfully.
  @retval EFI_INVALID_PARAMETER  The string is malformatted or Ip6Address is NULL.

**/
EFI_STATUS
EFIAPI
NetLibStrToIp6andPrefix (
  IN CONST CHAR16            *String,
  OUT      EFI_IPv6_ADDRESS  *Ip6Address,
  OUT      UINT8             *PrefixLength
  )
{
  RETURN_STATUS  Status;
  CHAR16         *EndPointer;

  Status = StrToIpv6Address (String, &EndPointer, Ip6Address, PrefixLength);
  if (RETURN_ERROR (Status) || (*EndPointer != L'\0')) {
    return EFI_INVALID_PARAMETER;
  } else {
    return EFI_SUCCESS;
  }
}

/**

  Convert one EFI_IPv6_ADDRESS to Null-terminated Unicode string.
  The text representation of address is defined in RFC 4291.

  @param[in]       Ip6Address     The pointer to the IPv6 address.
  @param[out]      String         The buffer to return the converted string.
  @param[in]       StringSize     The length in bytes of the input String.

  @retval EFI_SUCCESS             Convert to string successfully.
  @retval EFI_INVALID_PARAMETER   The input parameter is invalid.
  @retval EFI_BUFFER_TOO_SMALL    The BufferSize is too small for the result. BufferSize has been
                                  updated with the size needed to complete the request.
**/
EFI_STATUS
EFIAPI
NetLibIp6ToStr (
  IN         EFI_IPv6_ADDRESS  *Ip6Address,
  OUT        CHAR16            *String,
  IN         UINTN             StringSize
  )
{
  UINT16  Ip6Addr[8];
  UINTN   Index;
  UINTN   LongestZerosStart;
  UINTN   LongestZerosLength;
  UINTN   CurrentZerosStart;
  UINTN   CurrentZerosLength;
  CHAR16  Buffer[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff"];
  CHAR16  *Ptr;

  if ((Ip6Address == NULL) || (String == NULL) || (StringSize == 0)) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Convert the UINT8 array to an UINT16 array for easy handling.
  //
  ZeroMem (Ip6Addr, sizeof (Ip6Addr));
  for (Index = 0; Index < 16; Index++) {
    Ip6Addr[Index / 2] |= (Ip6Address->Addr[Index] << ((1 - (Index % 2)) << 3));
  }

  //
  // Find the longest zeros and mark it.
  //
  CurrentZerosStart  = DEFAULT_ZERO_START;
  CurrentZerosLength = 0;
  LongestZerosStart  = DEFAULT_ZERO_START;
  LongestZerosLength = 0;
  for (Index = 0; Index < 8; Index++) {
    if (Ip6Addr[Index] == 0) {
      if (CurrentZerosStart == DEFAULT_ZERO_START) {
        CurrentZerosStart  = Index;
        CurrentZerosLength = 1;
      } else {
        CurrentZerosLength++;
      }
    } else {
      if (CurrentZerosStart != DEFAULT_ZERO_START) {
        if ((CurrentZerosLength > 2) && ((LongestZerosStart == (DEFAULT_ZERO_START)) || (CurrentZerosLength > LongestZerosLength))) {
          LongestZerosStart  = CurrentZerosStart;
          LongestZerosLength = CurrentZerosLength;
        }

        CurrentZerosStart  = DEFAULT_ZERO_START;
        CurrentZerosLength = 0;
      }
    }
  }

  if ((CurrentZerosStart != DEFAULT_ZERO_START) && (CurrentZerosLength > 2)) {
    if ((LongestZerosStart == DEFAULT_ZERO_START) || (LongestZerosLength < CurrentZerosLength)) {
      LongestZerosStart  = CurrentZerosStart;
      LongestZerosLength = CurrentZerosLength;
    }
  }

  Ptr = Buffer;
  for (Index = 0; Index < 8; Index++) {
    if ((LongestZerosStart != DEFAULT_ZERO_START) && (Index >= LongestZerosStart) && (Index < LongestZerosStart + LongestZerosLength)) {
      if (Index == LongestZerosStart) {
        *Ptr++ = L':';
      }

      continue;
    }

    if (Index != 0) {
      *Ptr++ = L':';
    }

    Ptr += UnicodeSPrint (Ptr, 10, L"%x", Ip6Addr[Index]);
  }

  if ((LongestZerosStart != DEFAULT_ZERO_START) && (LongestZerosStart + LongestZerosLength == 8)) {
    *Ptr++ = L':';
  }

  *Ptr = L'\0';

  if ((UINTN)Ptr - (UINTN)Buffer > StringSize) {
    return EFI_BUFFER_TOO_SMALL;
  }

  StrCpyS (String, StringSize / sizeof (CHAR16), Buffer);

  return EFI_SUCCESS;
}

/**
  This function obtains the system guid from the smbios table.

  If SystemGuid is NULL, then ASSERT().

  @param[out]  SystemGuid     The pointer of the returned system guid.

  @retval EFI_SUCCESS         Successfully obtained the system guid.
  @retval EFI_NOT_FOUND       Did not find the SMBIOS table.

**/
EFI_STATUS
EFIAPI
NetLibGetSystemGuid (
  OUT EFI_GUID  *SystemGuid
  )
{
  EFI_STATUS                    Status;
  SMBIOS_TABLE_ENTRY_POINT      *SmbiosTable;
  SMBIOS_TABLE_3_0_ENTRY_POINT  *Smbios30Table;
  SMBIOS_STRUCTURE_POINTER      Smbios;
  SMBIOS_STRUCTURE_POINTER      SmbiosEnd;
  CHAR8                         *String;

  ASSERT (SystemGuid != NULL);

  SmbiosTable = NULL;
  Status      = EfiGetSystemConfigurationTable (&gEfiSmbios3TableGuid, (VOID **)&Smbios30Table);
  if (!(EFI_ERROR (Status) || (Smbios30Table == NULL))) {
    Smbios.Hdr    = (SMBIOS_STRUCTURE *)(UINTN)Smbios30Table->TableAddress;
    SmbiosEnd.Raw = (UINT8 *)(UINTN)(Smbios30Table->TableAddress + Smbios30Table->TableMaximumSize);
  } else {
    Status = EfiGetSystemConfigurationTable (&gEfiSmbiosTableGuid, (VOID **)&SmbiosTable);
    if (EFI_ERROR (Status) || (SmbiosTable == NULL)) {
      return EFI_NOT_FOUND;
    }

    Smbios.Hdr    = (SMBIOS_STRUCTURE *)(UINTN)SmbiosTable->TableAddress;
    SmbiosEnd.Raw = (UINT8 *)((UINTN)SmbiosTable->TableAddress + SmbiosTable->TableLength);
  }

  do {
    if (Smbios.Hdr->Type == 1) {
      if (Smbios.Hdr->Length < 0x19) {
        //
        // Older version did not support UUID.
        //
        return EFI_NOT_FOUND;
      }

      //
      // SMBIOS tables are byte packed so we need to do a byte copy to
      // prevend alignment faults on Itanium-based platform.
      //
      CopyMem (SystemGuid, &Smbios.Type1->Uuid, sizeof (EFI_GUID));
      return EFI_SUCCESS;
    }

    //
    // Go to the next SMBIOS structure. Each SMBIOS structure may include 2 parts:
    // 1. Formatted section; 2. Unformatted string section. So, 2 steps are needed
    // to skip one SMBIOS structure.
    //

    //
    // Step 1: Skip over formatted section.
    //
    String = (CHAR8 *)(Smbios.Raw + Smbios.Hdr->Length);

    //
    // Step 2: Skip over unformatted string section.
    //
    do {
      //
      // Each string is terminated with a NULL(00h) BYTE and the sets of strings
      // is terminated with an additional NULL(00h) BYTE.
      //
      for ( ; *String != 0; String++) {
      }

      if (*(UINT8 *)++String == 0) {
        //
        // Pointer to the next SMBIOS structure.
        //
        Smbios.Raw = (UINT8 *)++String;
        break;
      }
    } while (TRUE);
  } while (Smbios.Raw < SmbiosEnd.Raw);

  return EFI_NOT_FOUND;
}

/**
  Create Dns QName according the queried domain name.

  If DomainName is NULL, then ASSERT().

  QName is a domain name represented as a sequence of labels,
  where each label consists of a length octet followed by that
  number of octets. The QName terminates with the zero
  length octet for the null label of the root. Caller should
  take responsibility to free the buffer in returned pointer.

  @param  DomainName    The pointer to the queried domain name string.

  @retval NULL          Failed to fill QName.
  @return               QName filled successfully.

**/
CHAR8 *
EFIAPI
NetLibCreateDnsQName (
  IN  CHAR16  *DomainName
  )
{
  CHAR8  *QueryName;
  UINTN  QueryNameSize;
  CHAR8  *Header;
  CHAR8  *Tail;
  UINTN  Len;
  UINTN  Index;

  ASSERT (DomainName != NULL);

  QueryName     = NULL;
  QueryNameSize = 0;
  Header        = NULL;
  Tail          = NULL;

  //
  // One byte for first label length, one byte for terminated length zero.
  //
  QueryNameSize = StrLen (DomainName) + 2;

  if (QueryNameSize > DNS_MAX_NAME_SIZE) {
    return NULL;
  }

  QueryName = AllocateZeroPool (QueryNameSize);
  if (QueryName == NULL) {
    return NULL;
  }

  Header = QueryName;
  Tail   = Header + 1;
  Len    = 0;
  for (Index = 0; DomainName[Index] != 0; Index++) {
    *Tail = (CHAR8)DomainName[Index];
    if (*Tail == '.') {
      *Header = (CHAR8)Len;
      Header  = Tail;
      Tail++;
      Len = 0;
    } else {
      Tail++;
      Len++;
    }
  }

  *Header = (CHAR8)Len;
  *Tail   = 0;

  return QueryName;
}
