checksum.h File Reference

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Macros
#define	IPv4Checksum(Data, Count, Seed)   (~ChecksumFold(ChecksumCompute(Data, Count, Seed)))
#define	TCPv4Checksum(Data, Count, Seed)   (~ChecksumFold(csum_partial(Data, Count, Seed)))
#define	IPv4CorrectChecksum(Data, Count)    (BOOLEAN)(IPv4Checksum(Data, Count, 0) == DH2N(0x0000FFFF))
#define	TCPv4CorrectChecksum(TcpPseudoHeader, Data, Count)

Functions
ULONG	ChecksumFold (ULONG Sum)
ULONG	ChecksumCompute (PVOID Data, UINT Count, ULONG Seed)
unsigned int	csum_partial (const unsigned char *buff, int len, unsigned int sum)
ULONG	UDPv4ChecksumCalculate (PIPv4_HEADER IPHeader, PUCHAR PacketBuffer, ULONG DataLength)

Macro Definition Documentation

IPv4Checksum

#define IPv4Checksum	(		Data,
			Count,
			Seed
	)		(~ChecksumFold(ChecksumCompute(Data, Count, Seed)))

Definition at line 30 of file checksum.h.

IPv4CorrectChecksum

#define IPv4CorrectChecksum	(		Data,
			Count
	)		(BOOLEAN)(IPv4Checksum(Data, Count, 0) == DH2N(0x0000FFFF))

Definition at line 38 of file checksum.h.

TCPv4Checksum

#define TCPv4Checksum	(		Data,
			Count,
			Seed
	)		(~ChecksumFold(csum_partial(Data, Count, Seed)))

Definition at line 31 of file checksum.h.

TCPv4CorrectChecksum

#define TCPv4CorrectChecksum	(		TcpPseudoHeader,
			Data,
			Count
	)

Value:

    (BOOLEAN)(TCPv4Checksum(Data, Count, \
      TCPv4Checksum(TcpPseudoHeader, sizeof(TCPv4_PSEUDO_HEADER), \
      0)) == DH2N(0x0000FFFF))

Definition at line 46 of file checksum.h.

Function Documentation

ChecksumCompute()

ULONG ChecksumCompute	(	PVOID	Data,
		UINT	Count,
		ULONG	Seed
	)

Definition at line 27 of file checksum.c.

{
  register ULONG Sum = Seed;
 
  while (Count > 1)
    {
      Sum += *(PUSHORT)Data;
      Count -= 2;
      Data = (PVOID)((ULONG_PTR) Data + 2);
    }
 
  /* Add left-over byte, if any */
  if (Count > 0)
    {
      Sum += *(PUCHAR)Data;
    }
 
  return Sum;
}

ChecksumFold()

ULONG ChecksumFold

(

ULONG

Sum

)

Definition at line 15 of file checksum.c.

{
  /* Fold 32-bit sum to 16 bits */
  while (Sum >> 16)
    {
      Sum = (Sum & 0xFFFF) + (Sum >> 16);
    }
 
  return Sum;
}

csum_partial()

unsigned int csum_partial	(	const unsigned char *	buff,
		int	len,
		unsigned int	sum
	)

UDPv4ChecksumCalculate()

ULONG UDPv4ChecksumCalculate	(	PIPv4_HEADER	IPHeader,
		PUCHAR	PacketBuffer,
		ULONG	DataLength
	)

Definition at line 60 of file checksum.c.

{
  ULONG Sum = 0;
  USHORT TmpSum;
  ULONG i;
  BOOLEAN Pad;
 
  /* Pad the data if needed */
  Pad = (DataLength & 1);
  if (Pad)
      DataLength++;
 
  /* Add from the UDP header and data */
  for (i = 0; i < DataLength; i += 2)
  {
       TmpSum = ((PacketBuffer[i] << 8) & 0xFF00) +
                ((Pad && i == DataLength - 2) ? 0 : (PacketBuffer[i+1] & 0x00FF));
       Sum += TmpSum;
  }
 
  /* Add the source address */
  for (i = 0; i < sizeof(IPv4_RAW_ADDRESS); i += 2)
  {
       TmpSum = ((((PUCHAR)&IPHeader->SrcAddr)[i] << 8) & 0xFF00) +
                (((PUCHAR)&IPHeader->SrcAddr)[i+1] & 0x00FF);
       Sum += TmpSum;
  }
 
  /* Add the destination address */
  for (i = 0; i < sizeof(IPv4_RAW_ADDRESS); i += 2)
  {
       TmpSum = ((((PUCHAR)&IPHeader->DstAddr)[i] << 8) & 0xFF00) +
                (((PUCHAR)&IPHeader->DstAddr)[i+1] & 0x00FF);
       Sum += TmpSum;
  }
 
  /* Add the proto number and length */
  Sum += IPPROTO_UDP + (DataLength - (Pad ? 1 : 0));
 
  /* Fold the checksum and return the one's complement */
  return ~ChecksumFold(Sum);
}

Referenced by AddUDPHeaderIPv4(), and UDPReceive().