root/include/net/checksum.h

INCLUDED FROM

DEFINITIONS

1. csum_and_copy_from_user
2. csum_add
3. csum_sub
4. csum_block_add
5. csum_block_sub
6. csum_unfold
7. csum_replace4
8. csum_replace2
9. inet_proto_csum_replace2

/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              Checksumming functions for IP, TCP, UDP and so on
 *
 * Authors:     Jorge Cwik, <jorge@laser.satlink.net>
 *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 *              Borrows very liberally from tcp.c and ip.c, see those
 *              files for more names.
 *
 *              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.
 */

#ifndef _CHECKSUM_H
#define _CHECKSUM_H

#include <linux/errno.h>
#include <asm/types.h>
#include <asm/byteorder.h>
#include <asm/uaccess.h>
#include <asm/checksum.h>

#ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
static inline
__wsum csum_and_copy_from_user (const void __user *src, void *dst,
                                      int len, __wsum sum, int *err_ptr)
{
        if (access_ok(VERIFY_READ, src, len))
                return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);

        if (len)
                *err_ptr = -EFAULT;

        return sum;
}
#endif

#ifndef HAVE_CSUM_COPY_USER
static __inline__ __wsum csum_and_copy_to_user
(const void *src, void __user *dst, int len, __wsum sum, int *err_ptr)
{
        sum = csum_partial(src, len, sum);

        if (access_ok(VERIFY_WRITE, dst, len)) {
                if (copy_to_user(dst, src, len) == 0)
                        return sum;
        }
        if (len)
                *err_ptr = -EFAULT;

        return (__force __wsum)-1; /* invalid checksum */
}
#endif

static inline __wsum csum_add(__wsum csum, __wsum addend)
{
        u32 res = (__force u32)csum;
        res += (__force u32)addend;
        return (__force __wsum)(res + (res < (__force u32)addend));
}

static inline __wsum csum_sub(__wsum csum, __wsum addend)
{
        return csum_add(csum, ~addend);
}

static inline __wsum
csum_block_add(__wsum csum, __wsum csum2, int offset)
{
        u32 sum = (__force u32)csum2;
        if (offset&1)
                sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
        return csum_add(csum, (__force __wsum)sum);
}

static inline __wsum
csum_block_sub(__wsum csum, __wsum csum2, int offset)
{
        u32 sum = (__force u32)csum2;
        if (offset&1)
                sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
        return csum_sub(csum, (__force __wsum)sum);
}

static inline __wsum csum_unfold(__sum16 n)
{
        return (__force __wsum)n;
}

#define CSUM_MANGLED_0 ((__force __sum16)0xffff)

static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
{
        __be32 diff[] = { ~from, to };

        *sum = csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum_unfold(*sum)));
}

static inline void csum_replace2(__sum16 *sum, __be16 from, __be16 to)
{
        csum_replace4(sum, (__force __be32)from, (__force __be32)to);
}

struct sk_buff;
extern void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
                                     __be32 from, __be32 to, int pseudohdr);

static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
                                            __be16 from, __be16 to,
                                            int pseudohdr)
{
        inet_proto_csum_replace4(sum, skb, (__force __be32)from,
                                 (__force __be32)to, pseudohdr);
}

#endif