1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
use ip::IpNextHeaderProtocol;
use pnet_macros_support::types::u16be;
use std::net::{Ipv4Addr, Ipv6Addr};
use std::slice;
use std::u8;
pub trait Octets {
type Output;
fn octets(&self) -> Self::Output;
}
impl Octets for u64 {
type Output = [u8; 8];
fn octets(&self) -> Self::Output {
[(*self >> 56) as u8,
(*self >> 48) as u8,
(*self >> 40) as u8,
(*self >> 32) as u8,
(*self >> 24) as u8,
(*self >> 16) as u8,
(*self >> 8) as u8,
*self as u8]
}
}
impl Octets for u32 {
type Output = [u8; 4];
fn octets(&self) -> Self::Output {
[(*self >> 24) as u8, (*self >> 16) as u8, (*self >> 8) as u8, *self as u8]
}
}
impl Octets for u16 {
type Output = [u8; 2];
fn octets(&self) -> Self::Output {
[(*self >> 8) as u8, *self as u8]
}
}
impl Octets for u8 {
type Output = [u8; 1];
fn octets(&self) -> Self::Output {
[*self]
}
}
pub fn checksum(data: &[u8], skipword: usize) -> u16be {
if data.len() == 0 { return 0 }
assert_eq!(0, data.as_ptr() as usize % 2, "Cannot sum mis-aligned words at {:p}", data.as_ptr());
let sum = sum_be_words(data, skipword);
finalize_checksum(sum)
}
fn finalize_checksum(mut sum: u32) -> u16be {
while sum >> 16 != 0 {
sum = (sum >> 16) + (sum & 0xFFFF);
}
!sum as u16
}
pub fn ipv4_checksum(data: &[u8],
skipword: usize,
extra_data: &[u8],
source: &Ipv4Addr,
destination: &Ipv4Addr,
next_level_protocol: IpNextHeaderProtocol)
-> u16be {
let mut sum = 0u32;
sum += ipv4_word_sum(source);
sum += ipv4_word_sum(destination);
let IpNextHeaderProtocol(next_level_protocol) = next_level_protocol;
sum += next_level_protocol as u32;
let len = data.len() + extra_data.len();
sum += len as u32;
sum += sum_be_words(data, skipword);
sum += sum_be_words(extra_data, extra_data.len() / 2);
finalize_checksum(sum)
}
fn ipv4_word_sum(ip: &Ipv4Addr) -> u32 {
let octets = ip.octets();
((octets[0] as u32) << 8 | octets[1] as u32) + ((octets[2] as u32) << 8 | octets[3] as u32)
}
pub fn ipv6_checksum(data: &[u8],
skipword: usize,
extra_data: &[u8],
source: &Ipv6Addr,
destination: &Ipv6Addr,
next_level_protocol: IpNextHeaderProtocol)
-> u16be {
let mut sum = 0u32;
sum += ipv6_word_sum(source);
sum += ipv6_word_sum(destination);
let IpNextHeaderProtocol(next_level_protocol) = next_level_protocol;
sum += next_level_protocol as u32;
let len = data.len() + extra_data.len();
sum += len as u32;
sum += sum_be_words(data, skipword);
sum += sum_be_words(extra_data, extra_data.len() / 2);
finalize_checksum(sum)
}
fn ipv6_word_sum(ip: &Ipv6Addr) -> u32 {
ip.segments().iter().map(|x| *x as u32).sum()
}
fn sum_be_words(data: &[u8], mut skipword: usize) -> u32 {
if data.len() == 0 { return 0 }
debug_assert_eq!(0, data.as_ptr() as usize % 2, "Cannot sum mis-aligned words at {:p}", data.as_ptr());
let len = data.len();
let wdata: &[u16] = unsafe { slice::from_raw_parts(data.as_ptr() as *const u16, len / 2) };
skipword = ::std::cmp::min(skipword, wdata.len());
let mut sum = 0u32;
let mut i = 0;
while i < skipword {
sum += u16::from_be(unsafe { *wdata.get_unchecked(i) }) as u32;
i += 1;
}
i += 1;
while i < wdata.len() {
sum += u16::from_be(unsafe { *wdata.get_unchecked(i) }) as u32;
i += 1;
}
if len & 1 != 0 {
sum += (unsafe { *data.get_unchecked(len - 1) } as u32) << 8;
}
sum
}
#[cfg(test)]
mod tests {
use super::sum_be_words;
#[test]
fn sum_be_words_different_skipwords() {
let data = (0..11).collect::<Vec<u8>>();
assert_eq!(7190, sum_be_words(&data, 1));
assert_eq!(6676, sum_be_words(&data, 2));
assert_eq!(7705, sum_be_words(&data, 99));
assert_eq!(7705, sum_be_words(&data, 101));
}
}
#[cfg(all(test, feature = "benchmark"))]
mod checksum_benchmarks {
use super::checksum;
use test::{Bencher, black_box};
#[bench]
fn bench_checksum_small(b: &mut Bencher) {
let data = vec![99u8; 20];
b.iter(|| checksum(black_box(&data), 5));
}
#[bench]
fn bench_checksum_large(b: &mut Bencher) {
let data = vec![123u8; 1024];
b.iter(|| checksum(black_box(&data), 5));
}
}