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
  24#define CSUM_IP     0x01
  25#define CSUM_TCP    0x02
  26#define CSUM_UDP    0x04
  27#define CSUM_ALL    (CSUM_IP | CSUM_TCP | CSUM_UDP)
  28
  29uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq);
  30uint16_t net_checksum_finish(uint32_t sum);
  31uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
  32                             uint8_t *addrs, uint8_t *buf);
  33void net_checksum_calculate(uint8_t *data, int length, int csum_flag);
  34
  35static inline uint32_t
  36net_checksum_add(int len, uint8_t *buf)
  37{
  38    return net_checksum_add_cont(len, buf, 0);
  39}
  40
  41static inline uint16_t
  42net_checksum_finish_nozero(uint32_t sum)
  43{
  44    return net_checksum_finish(sum) ?: 0xFFFF;
  45}
  46
  47static inline uint16_t
  48net_raw_checksum(uint8_t *data, int length)
  49{
  50    return net_checksum_finish(net_checksum_add(length, data));
  51}
  52
  53/**
  54 * net_checksum_add_iov: scatter-gather vector checksumming
  55 *
  56 * @iov: input scatter-gather array
  57 * @iov_cnt: number of array elements
  58 * @iov_off: starting iov offset for checksumming
  59 * @size: length of data to be checksummed
  60 * @csum_offset: offset of the checksum chunk
  61 */
  62uint32_t net_checksum_add_iov(const struct iovec *iov,
  63                              const unsigned int iov_cnt,
  64                              uint32_t iov_off, uint32_t size,
  65                              uint32_t csum_offset);
  66
  67typedef struct toeplitz_key_st {
  68    uint32_t leftmost_32_bits;
  69    uint8_t *next_byte;
  70} net_toeplitz_key;
  71
  72static inline
  73void net_toeplitz_key_init(net_toeplitz_key *key, uint8_t *key_bytes)
  74{
  75    key->leftmost_32_bits = be32_to_cpu(*(uint32_t *)key_bytes);
  76    key->next_byte = key_bytes + sizeof(uint32_t);
  77}
  78
  79static inline
  80void net_toeplitz_add(uint32_t *result,
  81                      uint8_t *input,
  82                      uint32_t len,
  83                      net_toeplitz_key *key)
  84{
  85    register uint32_t accumulator = *result;
  86    register uint32_t leftmost_32_bits = key->leftmost_32_bits;
  87    register uint32_t byte;
  88
  89    for (byte = 0; byte < len; byte++) {
  90        register uint8_t input_byte = input[byte];
  91        register uint8_t key_byte = *(key->next_byte++);
  92        register uint8_t bit;
  93
  94        for (bit = 0; bit < 8; bit++) {
  95            if (input_byte & (1 << 7)) {
  96                accumulator ^= leftmost_32_bits;
  97            }
  98
  99            leftmost_32_bits =
 100                (leftmost_32_bits << 1) | ((key_byte & (1 << 7)) >> 7);
 101
 102            input_byte <<= 1;
 103            key_byte <<= 1;
 104        }
 105    }
 106
 107    key->leftmost_32_bits = leftmost_32_bits;
 108    *result = accumulator;
 109}
 110
 111#endif /* QEMU_NET_CHECKSUM_H */
 112