skcsum.c

这是Marvell Technology Group Ltd. 4355 (rev 12)网卡在linux下的驱动程序源代码

/******************************************************************************
 *
 * Name:	skcsum.c
 * Project:	GEnesis, PCI Gigabit Ethernet Adapter
 * Version:	$Revision: 2.4 $
 * Date:	$Date: 2007/03/14 16:20:40 $
 * Purpose:	Store/verify Internet checksum in send/receive packets.
 *
 ******************************************************************************/

/******************************************************************************
 *
 *	LICENSE:
 *	(C)Copyright Marvell.
 *	
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation; either version 2 of the License, or
 *	(at your option) any later version.
 *	
 *	The information in this file is provided "AS IS" without warranty.
 *	/LICENSE
 *
 ******************************************************************************/

#ifdef SK_USE_CSUM	/* Check if CSUM is to be used. */

#ifndef lint
static const char SysKonnectFileId[] =
	"@(#) $Id: skcsum.c,v 2.4 2007/03/14 16:20:40 rassmann Exp $ (C) SysKonnect.";
#endif	/* !lint */

/******************************************************************************
 *
 * Description:
 *
 * This is the "GEnesis" common module "CSUM".
 *
 * This module contains the code necessary to calculate, store, and verify the
 * Internet Checksum of IP, TCP, and UDP frames.
 *
 * "GEnesis" is an abbreviation of "Gigabit Ethernet Network System in Silicon"
 * and is the code name of this SysKonnect project.
 *
 * Compilation Options:
 *
 *	SK_USE_CSUM - Define if CSUM is to be used. Otherwise, CSUM will be an
 *	empty module.
 *
 *	SKCS_OVERWRITE_PROTO - Define to overwrite the default protocol id
 *	definitions. In this case, all SKCS_PROTO_xxx definitions must be made
 *	external.
 *
 *	SKCS_OVERWRITE_STATUS - Define to overwrite the default return status
 *	definitions. In this case, all SKCS_STATUS_xxx definitions must be made
 *	external.
 *
 * Include File Hierarchy:
 *
 *	"h/skdrv1st.h"
 *	"h/skcsum.h"
 *	"h/sktypes.h"
 *	"h/skqueue.h"
 *	"h/skdrv2nd.h"
 *
 ******************************************************************************/

#include "h/skdrv1st.h"
#include "h/skcsum.h"
#include "h/skdrv2nd.h"

/* defines ********************************************************************/

/* The size of an Ethernet MAC header. */
#define SKCS_ETHERNET_MAC_HEADER_SIZE			(6+6+2)

/* The size of the used topology's MAC header. */
#define	SKCS_MAC_HEADER_SIZE	SKCS_ETHERNET_MAC_HEADER_SIZE

/*
 * Field offsets within the IPv4 header.
 */

/* "Internet Header Version" and "Length". */
#define SKCS_OFS_IP_HEADER_VERSION_AND_LENGTH	0

/* "Total Length". */
#define SKCS_OFS_IP_TOTAL_LENGTH				2

/* "Flags" "Fragment Offset". */
#define SKCS_OFS_IP_FLAGS_AND_FRAGMENT_OFFSET	6

/* "Next Level Protocol" identifier. */
#define SKCS_OFS_IP_NEXT_LEVEL_PROTOCOL			9

/* Source IP address. */
#define SKCS_OFS_IP_SOURCE_ADDRESS				12

/* Destination IP address. */
#define SKCS_OFS_IP_DESTINATION_ADDRESS			16

#ifdef SK_IPV6_SUPPORT
/*
 * Field offsets in the IPv6 header
 */

/* Payload length field (size without IP header) */
#define SKCS_OFS_IP6_PAYLOAD_LENGTH				4

/* Next header identifier */
#define SKCS_OFS_IP6_NEXT_HEADER				6

/* Source IP adress (16 byte) */
#define SKCS_OFS_IP6_SOURCE_ADDRESS				8

/* Destination IP address (16 byte) */
#define SKCS_OFS_IP6_DESTINATION_ADDRESS		32

#endif	/* SK_IPV6_SUPPORT */

/*
 * Field offsets within the UDP header.
 */

/* UDP checksum. */
#define SKCS_OFS_UDP_CHECKSUM					6

/* IP "Next Level Protocol" identifiers (see RFC 790). */
#define SKCS_PROTO_ID_TCP		6	/* Transport Control Protocol */
#define SKCS_PROTO_ID_UDP		17	/* User Datagram Protocol */
#ifdef SK_IPV6_SUPPORT
#define SKCS_PROTO_ID_ICMPV6	58	/* ICMPv6 */
#define SKCS_PROTO_ID_NONE		59	/* No next header (used with IPv6) */
#endif	/* SK_IPV6_SUPPORT */

/* IP "Don't Fragment" bit. */
#define SKCS_IP_DONT_FRAGMENT	SKCS_HTON16(0x4000)

/* Add a byte offset to a pointer. */
#define SKCS_IDX(pPtr, Ofs)	((void *) ((char *) (pPtr) + (Ofs)))

/* Check whether offset is within buffer. */
#define SKCS_IDX_CHECK(Le, Ofs)	((Le) <= (Ofs))

/*
 * Macros that convert host to network representation and vice versa, i.e.
 * little/big endian conversion on little endian machines only.
 */
#ifdef SK_LITTLE_ENDIAN
#define SKCS_HTON16(Val16)	(((unsigned) (Val16) >> 8) | (((Val16) & 0xff) << 8))
#endif	/* SK_LITTLE_ENDIAN */
#ifdef SK_BIG_ENDIAN
#define SKCS_HTON16(Val16)	(Val16)
#endif	/* SK_BIG_ENDIAN */
#define SKCS_NTOH16(Val16)	SKCS_HTON16(Val16)

/* typedefs *******************************************************************/

/* function prototypes ********************************************************/

/******************************************************************************
 *
 *	SkCsGetSendInfo - get checksum information for a send packet
 *
 * Description:
 *	Get all checksum information necessary to send a TCP or UDP packet. The
 *	function checks the IP header passed to it. If the high-level protocol
 *	is either TCP or UDP the pseudo header checksum is calculated and
 *	returned.
 *
 *	The function returns the total length of the IP header (including any
 *	IP option fields), which is the same as the start offset of the IP data
 *	which in turn is the start offset of the TCP or UDP header.
 *
 *	The function also returns the TCP or UDP pseudo header checksum, which
 *	should be used as the start value for the hardware checksum calculation.
 *	(Note that any actual pseudo header checksum can never calculate to
 *	zero.)
 *
 * Note:
 *	There is a bug in the GENESIS ASIC which may lead to wrong checksums.
 *
 * Arguments:
 *	pAc - A pointer to the adapter context struct.
 *
 *	pIpHeader - Pointer to IP header. Must be at least the IP header *not*
 *	including any option fields, i.e. at least 20 bytes.
 *
 *	Note: This pointer will be used to address 8-, 16-, and 32-bit
 *	variables with the respective alignment offsets relative to the pointer.
 *	Thus, the pointer should point to a 32-bit aligned address. If the
 *	target system cannot address 32-bit variables on non 32-bit aligned
 *	addresses, then the pointer *must* point to a 32-bit aligned address.
 *
 *	pPacketInfo - A pointer to the packet information structure for this
 *	packet. Before calling this SkCsGetSendInfo(), the following field must
 *	be initialized:
 *
 *		ProtocolFlags - Initialize with any combination of
 *		SKCS_PROTO_XXX bit flags. SkCsGetSendInfo() will only work on
 *		the protocols specified here. Any protocol(s) not specified
 *		here will be ignored.
 *
 *		Note: Only one checksum can be calculated in hardware. Thus, if
 *		SKCS_PROTO_IP is specified in the 'ProtocolFlags',
 *		SkCsGetSendInfo() must calculate the IP header checksum in
 *		software. It might be a better idea to have the calling
 *		protocol stack calculate the IP header checksum.
 *
 * Returns: N/A
 *	On return, the following fields in 'pPacketInfo' may or may not have
 *	been filled with information, depending on the protocol(s) found in the
 *	packet:
 *
 *	ProtocolFlags - Returns the SKCS_PROTO_XXX bit flags of the protocol(s)
 *	that were both requested by the caller and actually found in the packet.
 *	Protocol(s) not specified by the caller and/or not found in the packet
 *	will have their respective SKCS_PROTO_XXX bit flags reset.
 *
 *	Note: For IP fragments, TCP and UDP packet information is ignored.
 *
 *	IpHeaderLength - The total length in bytes of the complete IP header
 *	including any option fields is returned here. This is the start offset
 *	of the IP data, i.e. the TCP or UDP header if present.
 *
 *	IpHeaderChecksum - If IP has been specified in the 'ProtocolFlags', the
 *	16-bit Internet Checksum of the IP header is returned here. This value
 *	is to be stored into the packet's 'IP Header Checksum' field.
 *
 *	PseudoHeaderChecksum - If this is a TCP or UDP packet and if TCP or UDP
 *	has been specified in the 'ProtocolFlags', the 16-bit Internet Checksum
 *	of the TCP or UDP pseudo header is returned here.
 */
void SkCsGetSendInfo(
SK_AC				*pAc,			/* Adapter context struct. */
void				*pIpHeader,		/* IP header. */
SKCS_PACKET_INFO	*pPacketInfo,	/* Packet information struct. */
int					NetNumber)		/* Net number */
{
	/* Internet Header Version found in IP header. */
	unsigned InternetHeaderVersion;

	/* Length of the IP header as found in IP header. */
	unsigned IpHeaderLength;

	/* Bit field specifiying the desired/found protocols. */
	unsigned ProtocolFlags;

	/* Next level protocol identifier found in IP header. */
	unsigned NextLevelProtocol;

	/* Length of IP data portion. */
	unsigned IpDataLength;

	/* TCP/UDP pseudo header checksum. */
	unsigned long PseudoHeaderChecksum;

	/* Pointer to next level protocol statistics structure. */
	SKCS_PROTO_STATS *NextLevelProtoStats;

	/* Temporary variable. */
	unsigned Tmp;

	Tmp = *(SK_U8 *)
		SKCS_IDX(pIpHeader, SKCS_OFS_IP_HEADER_VERSION_AND_LENGTH);

	/* Get the Internet Header Version (IHV). */
	/* Note: The IHV is stored in the upper four bits. */

	InternetHeaderVersion = Tmp >> 4;

	/* Check the Internet Header Version. */
	/* Note: We currently only support IP version 4. */

	if (InternetHeaderVersion != 4) {	/* IPv4? */
		SK_DBG_MSG(pAc, SK_DBGMOD_CSUM, SK_DBGCAT_ERR | SK_DBGCAT_TX,
			("Tx: Unknown Internet Header Version %u.\n",
			InternetHeaderVersion));
		pPacketInfo->ProtocolFlags = 0;
		pAc->Csum.ProtoStats[NetNumber][SKCS_PROTO_STATS_IP].TxUnableCts++;
		return;
	}

	/* Get the IP header length (IHL). */
	/*
	 * Note: The IHL is stored in the lower four bits as the number of
	 * 4-byte words.
	 */

	IpHeaderLength = (Tmp & 0xf) * 4;
	pPacketInfo->IpHeaderLength = IpHeaderLength;

	/* Check the IP header length. */

	/* 04-Aug-1998 sw - Really check the IHL? Necessary? */

	if (IpHeaderLength < 5*4) {
		SK_DBG_MSG(pAc, SK_DBGMOD_CSUM, SK_DBGCAT_ERR | SK_DBGCAT_TX,
			("Tx: Invalid IP Header Length %u.\n", IpHeaderLength));
		pPacketInfo->ProtocolFlags = 0;
		pAc->Csum.ProtoStats[NetNumber][SKCS_PROTO_STATS_IP].TxUnableCts++;
		return;
	}

	/* This is an IPv4 frame with a header of valid length. */

	pAc->Csum.ProtoStats[NetNumber][SKCS_PROTO_STATS_IP].TxOkCts++;

	/* Check if we should calculate the IP header checksum. */

	ProtocolFlags = pPacketInfo->ProtocolFlags;

	if (ProtocolFlags & SKCS_PROTO_IP) {
		pPacketInfo->IpHeaderChecksum =
			SkCsCalculateChecksum(pIpHeader, IpHeaderLength);
	}

	/* Get the next level protocol identifier. */

	NextLevelProtocol =
		*(SK_U8 *) SKCS_IDX(pIpHeader, SKCS_OFS_IP_NEXT_LEVEL_PROTOCOL);

	/*
	 * Check if this is a TCP or UDP frame and if we should calculate the
	 * TCP/UDP pseudo header checksum.
	 *
	 * Also clear all protocol bit flags of protocols not present in the
	 * frame.
	 */

	if ((ProtocolFlags & SKCS_PROTO_TCP) != 0 &&
		NextLevelProtocol == SKCS_PROTO_ID_TCP) {
		/* TCP/IP frame. */
		ProtocolFlags &= SKCS_PROTO_TCP | SKCS_PROTO_IP;
		NextLevelProtoStats =
			&pAc->Csum.ProtoStats[NetNumber][SKCS_PROTO_STATS_TCP];
	}
	else if ((ProtocolFlags & SKCS_PROTO_UDP) != 0 &&
		NextLevelProtocol == SKCS_PROTO_ID_UDP) {
		/* UDP/IP frame. */
		ProtocolFlags &= SKCS_PROTO_UDP | SKCS_PROTO_IP;
		NextLevelProtoStats =
			&pAc->Csum.ProtoStats[NetNumber][SKCS_PROTO_STATS_UDP];
	}
	else {
		/*
		 * Either not a TCP or UDP frame and/or TCP/UDP processing not
		 * specified.
		 */
		pPacketInfo->ProtocolFlags = ProtocolFlags & SKCS_PROTO_IP;
		return;
	}

	/* Check if this is an IP fragment. */

	/*
	 * Note: An IP fragment has a non-zero "Fragment Offset" field and/or
	 * the "More Fragments" bit set. Thus, if both the "Fragment Offset"
	 * and the "More Fragments" are zero, it is *not* a fragment. We can
	 * easily check both at the same time since they are in the same 16-bit
	 * word.
	 */

	if ((*(SK_U16 *)
		SKCS_IDX(pIpHeader, SKCS_OFS_IP_FLAGS_AND_FRAGMENT_OFFSET) &
		~SKCS_IP_DONT_FRAGMENT) != 0) {
		/* IP fragment; ignore all other protocols. */
		pPacketInfo->ProtocolFlags = ProtocolFlags & SKCS_PROTO_IP;
		NextLevelProtoStats->TxUnableCts++;
		return;
	}

	/*
	 * Calculate the TCP/UDP pseudo header checksum.
	 */

	/* Get total length of IP header and data. */

	IpDataLength =
		*(SK_U16 *) SKCS_IDX(pIpHeader, SKCS_OFS_IP_TOTAL_LENGTH);