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 #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
  29 uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq);
  30 uint16_t net_checksum_finish(uint32_t sum);
  31 uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
  32                              uint8_t *addrs, uint8_t *buf);
  33 void net_checksum_calculate(uint8_t *data, int length, int csum_flag);
  34
  35 static inline uint32_t
  36 net_checksum_add(int len, uint8_t *buf)
  37 {
  38     return net_checksum_add_cont(len, buf, 0);
  39 }
  40
  41 static inline uint16_t
  42 net_checksum_finish_nozero(uint32_t sum)
  43 {
  44     return net_checksum_finish(sum) ?: 0xFFFF;
  45 }
  46
  47 static inline uint16_t
  48 net_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  */
  62 uint32_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
  67 typedef struct toeplitz_key_st {
  68     uint32_t leftmost_32_bits;
  69     uint8_t *next_byte;
  70 } net_toeplitz_key;
  71
  72 static inline
  73 void 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
  79 static inline
  80 void 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 */