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1 : : /*
2 : : * Copyright (c) 2008, 2009, 2010, 2011, 2013, 2015 Nicira, Inc.
3 : : *
4 : : * Licensed under the Apache License, Version 2.0 (the "License");
5 : : * you may not use this file except in compliance with the License.
6 : : * You may obtain a copy of the License at:
7 : : *
8 : : * http://www.apache.org/licenses/LICENSE-2.0
9 : : *
10 : : * Unless required by applicable law or agreed to in writing, software
11 : : * distributed under the License is distributed on an "AS IS" BASIS,
12 : : * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 : : * See the License for the specific language governing permissions and
14 : : * limitations under the License.
15 : : */
16 : :
17 : : #include <config.h>
18 : : #include "csum.h"
19 : : #include "unaligned.h"
20 : :
21 : : #ifndef __CHECKER__
22 : : /* Returns the IP checksum of the 'n' bytes in 'data'.
23 : : *
24 : : * The return value has the same endianness as the data. That is, if 'data'
25 : : * consists of a packet in network byte order, then the return value is a value
26 : : * in network byte order, and if 'data' consists of a data structure in host
27 : : * byte order, then the return value is in host byte order. */
28 : : ovs_be16
29 : 12087 : csum(const void *data, size_t n)
30 : : {
31 : 12087 : return csum_finish(csum_continue(0, data, n));
32 : : }
33 : :
34 : : /* Adds the 'n' bytes in 'data' to the partial IP checksum 'partial' and
35 : : * returns the updated checksum. (To start a new checksum, pass 0 for
36 : : * 'partial'. To obtain the finished checksum, pass the return value to
37 : : * csum_finish().) */
38 : : uint32_t
39 : 17388 : csum_continue(uint32_t partial, const void *data_, size_t n)
40 : : {
41 : 17388 : const ovs_be16 *data = data_;
42 : :
43 [ + + ]: 282468 : for (; n > 1; n -= 2, data++) {
44 : 265080 : partial = csum_add16(partial, get_unaligned_be16(data));
45 : : }
46 [ + + ]: 17388 : if (n) {
47 : 94 : partial += *(uint8_t *) data;
48 : : }
49 : 17388 : return partial;
50 : : }
51 : :
52 : : /* Returns the IP checksum corresponding to 'partial', which is a value updated
53 : : * by some combination of csum_add16(), csum_add32(), and csum_continue().
54 : : *
55 : : * The return value has the same endianness as the checksummed data. That is,
56 : : * if the data consist of a packet in network byte order, then the return value
57 : : * is a value in network byte order, and if the data are a data structure in
58 : : * host byte order, then the return value is in host byte order. */
59 : : ovs_be16
60 : 21111 : csum_finish(uint32_t partial)
61 : : {
62 [ + + ]: 40291 : while (partial >> 16) {
63 : 19180 : partial = (partial & 0xffff) + (partial >> 16);
64 : : }
65 : 21111 : return ~partial;
66 : : }
67 : :
68 : : /* Returns the new checksum for a packet in which the checksum field previously
69 : : * contained 'old_csum' and in which a field that contained 'old_u16' was
70 : : * changed to contain 'new_u16'. */
71 : : ovs_be16
72 : 3721 : recalc_csum16(ovs_be16 old_csum, ovs_be16 old_u16, ovs_be16 new_u16)
73 : : {
74 : : /* Ones-complement arithmetic is endian-independent, so this code does not
75 : : * use htons() or ntohs().
76 : : *
77 : : * See RFC 1624 for formula and explanation. */
78 : 3721 : uint16_t hc_complement = ~old_csum;
79 : 3721 : uint16_t m_complement = ~old_u16;
80 : 3721 : uint16_t m_prime = new_u16;
81 : 3721 : uint32_t sum = hc_complement + m_complement + m_prime;
82 : 3721 : return csum_finish(sum);
83 : : }
84 : :
85 : : /* Returns the new checksum for a packet in which the checksum field previously
86 : : * contained 'old_csum' and in which a field that contained 'old_u32' was
87 : : * changed to contain 'new_u32'. */
88 : : ovs_be16
89 : 260 : recalc_csum32(ovs_be16 old_csum, ovs_be32 old_u32, ovs_be32 new_u32)
90 : : {
91 : 260 : return recalc_csum16(recalc_csum16(old_csum, old_u32, new_u32),
92 : 520 : old_u32 >> 16, new_u32 >> 16);
93 : : }
94 : :
95 : : /* Returns the new checksum for a packet in which the checksum field previously
96 : : * contained 'old_csum' and in which a field that contained the 6 bytes at
97 : : * 'old_mac' was changed to contain the 6 bytes at 'new_mac'. */
98 : : ovs_be16
99 : 8 : recalc_csum48(ovs_be16 old_csum, const struct eth_addr old_mac,
100 : : const struct eth_addr new_mac)
101 : : {
102 : 8 : ovs_be16 new_csum = old_csum;
103 : :
104 [ + + ]: 32 : for (int i = 0; i < 3; ++i) {
105 : 24 : new_csum = recalc_csum16(new_csum, old_mac.be16[i], new_mac.be16[i]);
106 : : }
107 : :
108 : 8 : return new_csum;
109 : : }
110 : :
111 : : /* Returns the new checksum for a packet in which the checksum field previously
112 : : * contained 'old_csum' and in which a field that contained 'old_u32[4]' was
113 : : * changed to contain 'new_u32[4]'. */
114 : : ovs_be16
115 : 19 : recalc_csum128(ovs_be16 old_csum, ovs_16aligned_be32 old_u32[4],
116 : : const ovs_be32 new_u32[4])
117 : : {
118 : 19 : ovs_be16 new_csum = old_csum;
119 : : int i;
120 : :
121 [ + + ]: 95 : for (i = 0; i < 4; ++i) {
122 : 76 : new_csum = recalc_csum32(new_csum,
123 : 152 : get_16aligned_be32(&old_u32[i]), new_u32[i]);
124 : : }
125 : 19 : return new_csum;
126 : : }
127 : : #else /* __CHECKER__ */
128 : : /* Making sparse happy with these functions also makes them unreadable, so
129 : : * don't bother to show it their implementations. */
130 : : #endif
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