xref: /openbmc/qemu/include/net/checksum.h (revision 31ee8950)
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
net_checksum_add(int len,uint8_t * buf)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
net_checksum_finish_nozero(uint32_t sum)42 net_checksum_finish_nozero(uint32_t sum)
43 {
44     return net_checksum_finish(sum) ?: 0xFFFF;
45 }
46 
47 static inline uint16_t
net_raw_checksum(uint8_t * data,int length)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
net_toeplitz_key_init(net_toeplitz_key * key,uint8_t * key_bytes)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
net_toeplitz_add(uint32_t * result,uint8_t * input,uint32_t len,net_toeplitz_key * key)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 */
112