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"
  22 struct iovec;
  23
  24 uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq);
  25 uint16_t net_checksum_finish(uint32_t sum);
  26 uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
  27                              uint8_t *addrs, uint8_t *buf);
  28 void net_checksum_calculate(uint8_t *data, int length);
  29
  30 static inline uint32_t
  31 net_checksum_add(int len, uint8_t *buf)
  32 {
  33     return net_checksum_add_cont(len, buf, 0);
  34 }
  35
  36 static inline uint16_t
  37 net_raw_checksum(uint8_t *data, int length)
  38 {
  39     return net_checksum_finish(net_checksum_add(length, data));
  40 }
  41
  42 /**
  43  * net_checksum_add_iov: scatter-gather vector checksumming
  44  *
  45  * @iov: input scatter-gather array
  46  * @iov_cnt: number of array elements
  47  * @iov_off: starting iov offset for checksumming
  48  * @size: length of data to be checksummed
  49  * @csum_offset: offset of the checksum chunk
  50  */
  51 uint32_t net_checksum_add_iov(const struct iovec *iov,
  52                               const unsigned int iov_cnt,
  53                               uint32_t iov_off, uint32_t size,
  54                               uint32_t csum_offset);
  55
  56 typedef struct toeplitz_key_st {
  57     uint32_t leftmost_32_bits;
  58     uint8_t *next_byte;
  59 } net_toeplitz_key;
  60
  61 static inline
  62 void net_toeplitz_key_init(net_toeplitz_key *key, uint8_t *key_bytes)
  63 {
  64     key->leftmost_32_bits = be32_to_cpu(*(uint32_t *)key_bytes);
  65     key->next_byte = key_bytes + sizeof(uint32_t);
  66 }
  67
  68 static inline
  69 void net_toeplitz_add(uint32_t *result,
  70                       uint8_t *input,
  71                       uint32_t len,
  72                       net_toeplitz_key *key)
  73 {
  74     register uint32_t accumulator = *result;
  75     register uint32_t leftmost_32_bits = key->leftmost_32_bits;
  76     register uint32_t byte;
  77
  78     for (byte = 0; byte < len; byte++) {
  79         register uint8_t input_byte = input[byte];
  80         register uint8_t key_byte = *(key->next_byte++);
  81         register uint8_t bit;
  82
  83         for (bit = 0; bit < 8; bit++) {
  84             if (input_byte & (1 << 7)) {
  85                 accumulator ^= leftmost_32_bits;
  86             }
  87
  88             leftmost_32_bits =
  89                 (leftmost_32_bits << 1) | ((key_byte & (1 << 7)) >> 7);
  90
  91             input_byte <<= 1;
  92             key_byte <<= 1;
  93         }
  94     }
  95
  96     key->leftmost_32_bits = leftmost_32_bits;
  97     *result = accumulator;
  98 }
  99
 100 #endif /* QEMU_NET_CHECKSUM_H */