LXR qemu/include/net/checksum.h

   1/*
   2 *  IP checksumming functions.
   3 *  (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
   4 *
   5 *  This program is free software; you can redistribute it and/or modify
   6 *  it under the terms of the GNU General Public License as published by
   7 *  the Free Software Foundation; under version 2 of the License.
   8 *
   9 *  This program is distributed in the hope that it will be useful,
  10 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 *  GNU General Public License for more details.
  13 *
  14 *  You should have received a copy of the GNU General Public License
  15 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18#ifndef QEMU_NET_CHECKSUM_H
  19#define QEMU_NET_CHECKSUM_H
  20
  21#include "qemu/bswap.h"
  22struct iovec;
  23
  24uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq);
  25uint16_t net_checksum_finish(uint32_t sum);
  26uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
  27                             uint8_t *addrs, uint8_t *buf);
  28void net_checksum_calculate(uint8_t *data, int length);
  29
  30static inline uint32_t
  31net_checksum_add(int len, uint8_t *buf)
  32{
  33    return net_checksum_add_cont(len, buf, 0);
  34}
  35
  36static inline uint16_t
  37net_checksum_finish_nozero(uint32_t sum)
  38{
  39    return net_checksum_finish(sum) ?: 0xFFFF;
  40}
  41
  42static inline uint16_t
  43net_raw_checksum(uint8_t *data, int length)
  44{
  45    return net_checksum_finish(net_checksum_add(length, data));
  46}
  47
  48/**
  49 * net_checksum_add_iov: scatter-gather vector checksumming
  50 *
  51 * @iov: input scatter-gather array
  52 * @iov_cnt: number of array elements
  53 * @iov_off: starting iov offset for checksumming
  54 * @size: length of data to be checksummed
  55 * @csum_offset: offset of the checksum chunk
  56 */
  57uint32_t net_checksum_add_iov(const struct iovec *iov,
  58                              const unsigned int iov_cnt,
  59                              uint32_t iov_off, uint32_t size,
  60                              uint32_t csum_offset);
  61
  62typedef struct toeplitz_key_st {
  63    uint32_t leftmost_32_bits;
  64    uint8_t *next_byte;
  65} net_toeplitz_key;
  66
  67static inline
  68void net_toeplitz_key_init(net_toeplitz_key *key, uint8_t *key_bytes)
  69{
  70    key->leftmost_32_bits = be32_to_cpu(*(uint32_t *)key_bytes);
  71    key->next_byte = key_bytes + sizeof(uint32_t);
  72}
  73
  74static inline
  75void net_toeplitz_add(uint32_t *result,
  76                      uint8_t *input,
  77                      uint32_t len,
  78                      net_toeplitz_key *key)
  79{
  80    register uint32_t accumulator = *result;
  81    register uint32_t leftmost_32_bits = key->leftmost_32_bits;
  82    register uint32_t byte;
  83
  84    for (byte = 0; byte < len; byte++) {
  85        register uint8_t input_byte = input[byte];
  86        register uint8_t key_byte = *(key->next_byte++);
  87        register uint8_t bit;
  88
  89        for (bit = 0; bit < 8; bit++) {
  90            if (input_byte & (1 << 7)) {
  91                accumulator ^= leftmost_32_bits;
  92            }
  93
  94            leftmost_32_bits =
  95                (leftmost_32_bits << 1) | ((key_byte & (1 << 7)) >> 7);
  96
  97            input_byte <<= 1;
  98            key_byte <<= 1;
  99        }
 100    }
 101
 102    key->leftmost_32_bits = leftmost_32_bits;
 103    *result = accumulator;
 104}
 105
 106#endif /* QEMU_NET_CHECKSUM_H */
 107