0dacea92d2
The checksum algorithm used by IPv4, TCP and UDP allows a zero value to be represented by either 0x0000 and 0xFFFF. But per RFC 768, a zero UDP checksum must be transmitted as 0xFFFF because 0x0000 is a special value meaning no checksum. Substitute 0xFFFF whenever a checksum is computed as zero when modifying a UDP datagram header. Doing this on IPv4 and TCP checksums is unnecessary but legal. Add a wrapper for net_checksum_finish() that makes the substitution. (We can't just change net_checksum_finish(), as that function is also used by receivers to verify checksums, and in that case the expected value is always 0x0000.) Signed-off-by: Ed Swierk <eswierk@skyportsystems.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
107 lines
3.1 KiB
C
107 lines
3.1 KiB
C
/*
|
|
* IP checksumming functions.
|
|
* (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
|
|
*
|
|
* 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; under version 2 of the License.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifndef QEMU_NET_CHECKSUM_H
|
|
#define QEMU_NET_CHECKSUM_H
|
|
|
|
#include "qemu/bswap.h"
|
|
struct iovec;
|
|
|
|
uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq);
|
|
uint16_t net_checksum_finish(uint32_t sum);
|
|
uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
|
|
uint8_t *addrs, uint8_t *buf);
|
|
void net_checksum_calculate(uint8_t *data, int length);
|
|
|
|
static inline uint32_t
|
|
net_checksum_add(int len, uint8_t *buf)
|
|
{
|
|
return net_checksum_add_cont(len, buf, 0);
|
|
}
|
|
|
|
static inline uint16_t
|
|
net_checksum_finish_nozero(uint32_t sum)
|
|
{
|
|
return net_checksum_finish(sum) ?: 0xFFFF;
|
|
}
|
|
|
|
static inline uint16_t
|
|
net_raw_checksum(uint8_t *data, int length)
|
|
{
|
|
return net_checksum_finish(net_checksum_add(length, data));
|
|
}
|
|
|
|
/**
|
|
* net_checksum_add_iov: scatter-gather vector checksumming
|
|
*
|
|
* @iov: input scatter-gather array
|
|
* @iov_cnt: number of array elements
|
|
* @iov_off: starting iov offset for checksumming
|
|
* @size: length of data to be checksummed
|
|
* @csum_offset: offset of the checksum chunk
|
|
*/
|
|
uint32_t net_checksum_add_iov(const struct iovec *iov,
|
|
const unsigned int iov_cnt,
|
|
uint32_t iov_off, uint32_t size,
|
|
uint32_t csum_offset);
|
|
|
|
typedef struct toeplitz_key_st {
|
|
uint32_t leftmost_32_bits;
|
|
uint8_t *next_byte;
|
|
} net_toeplitz_key;
|
|
|
|
static inline
|
|
void net_toeplitz_key_init(net_toeplitz_key *key, uint8_t *key_bytes)
|
|
{
|
|
key->leftmost_32_bits = be32_to_cpu(*(uint32_t *)key_bytes);
|
|
key->next_byte = key_bytes + sizeof(uint32_t);
|
|
}
|
|
|
|
static inline
|
|
void net_toeplitz_add(uint32_t *result,
|
|
uint8_t *input,
|
|
uint32_t len,
|
|
net_toeplitz_key *key)
|
|
{
|
|
register uint32_t accumulator = *result;
|
|
register uint32_t leftmost_32_bits = key->leftmost_32_bits;
|
|
register uint32_t byte;
|
|
|
|
for (byte = 0; byte < len; byte++) {
|
|
register uint8_t input_byte = input[byte];
|
|
register uint8_t key_byte = *(key->next_byte++);
|
|
register uint8_t bit;
|
|
|
|
for (bit = 0; bit < 8; bit++) {
|
|
if (input_byte & (1 << 7)) {
|
|
accumulator ^= leftmost_32_bits;
|
|
}
|
|
|
|
leftmost_32_bits =
|
|
(leftmost_32_bits << 1) | ((key_byte & (1 << 7)) >> 7);
|
|
|
|
input_byte <<= 1;
|
|
key_byte <<= 1;
|
|
}
|
|
}
|
|
|
|
key->leftmost_32_bits = leftmost_32_bits;
|
|
*result = accumulator;
|
|
}
|
|
|
|
#endif /* QEMU_NET_CHECKSUM_H */
|