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
|
mod table;
use self::table::{DECODE_TABLE, ENCODE_TABLE};
use crate::hpack::DecoderError;
use bytes::{BufMut, BytesMut};
// Constructed in the generated `table.rs` file
struct Decoder {
state: usize,
maybe_eos: bool,
}
// These flags must match the ones in genhuff.rs
const MAYBE_EOS: u8 = 1;
const DECODED: u8 = 2;
const ERROR: u8 = 4;
pub fn decode(src: &[u8], buf: &mut BytesMut) -> Result<BytesMut, DecoderError> {
let mut decoder = Decoder::new();
// Max compression ratio is >= 0.5
buf.reserve(src.len() << 1);
for b in src {
if let Some(b) = decoder.decode4(b >> 4)? {
buf.put_u8(b);
}
if let Some(b) = decoder.decode4(b & 0xf)? {
buf.put_u8(b);
}
}
if !decoder.is_final() {
return Err(DecoderError::InvalidHuffmanCode);
}
Ok(buf.split())
}
pub fn encode(src: &[u8], dst: &mut BytesMut) {
let mut bits: u64 = 0;
let mut bits_left = 40;
for &b in src {
let (nbits, code) = ENCODE_TABLE[b as usize];
bits |= code << (bits_left - nbits);
bits_left -= nbits;
while bits_left <= 32 {
dst.put_u8((bits >> 32) as u8);
bits <<= 8;
bits_left += 8;
}
}
if bits_left != 40 {
// This writes the EOS token
bits |= (1 << bits_left) - 1;
dst.put_u8((bits >> 32) as u8);
}
}
impl Decoder {
fn new() -> Decoder {
Decoder {
state: 0,
maybe_eos: false,
}
}
// Decodes 4 bits
fn decode4(&mut self, input: u8) -> Result<Option<u8>, DecoderError> {
// (next-state, byte, flags)
let (next, byte, flags) = DECODE_TABLE[self.state][input as usize];
if flags & ERROR == ERROR {
// Data followed the EOS marker
return Err(DecoderError::InvalidHuffmanCode);
}
let mut ret = None;
if flags & DECODED == DECODED {
ret = Some(byte);
}
self.state = next;
self.maybe_eos = flags & MAYBE_EOS == MAYBE_EOS;
Ok(ret)
}
fn is_final(&self) -> bool {
self.state == 0 || self.maybe_eos
}
}
#[cfg(test)]
mod test {
use super::*;
fn decode(src: &[u8]) -> Result<BytesMut, DecoderError> {
let mut buf = BytesMut::new();
super::decode(src, &mut buf)
}
#[test]
fn decode_single_byte() {
assert_eq!("o", decode(&[0b00111111]).unwrap());
assert_eq!("0", decode(&[0x0 + 7]).unwrap());
assert_eq!("A", decode(&[(0x21 << 2) + 3]).unwrap());
}
#[test]
fn single_char_multi_byte() {
assert_eq!("#", decode(&[255, 160 + 15]).unwrap());
assert_eq!("$", decode(&[255, 200 + 7]).unwrap());
assert_eq!("\x0a", decode(&[255, 255, 255, 240 + 3]).unwrap());
}
#[test]
fn multi_char() {
assert_eq!("!0", decode(&[254, 1]).unwrap());
assert_eq!(" !", decode(&[0b01010011, 0b11111000]).unwrap());
}
#[test]
fn encode_single_byte() {
let mut dst = BytesMut::with_capacity(1);
encode(b"o", &mut dst);
assert_eq!(&dst[..], &[0b00111111]);
dst.clear();
encode(b"0", &mut dst);
assert_eq!(&dst[..], &[0x0 + 7]);
dst.clear();
encode(b"A", &mut dst);
assert_eq!(&dst[..], &[(0x21 << 2) + 3]);
}
#[test]
fn encode_decode_str() {
const DATA: &'static [&'static str] = &[
"hello world",
":method",
":scheme",
":authority",
"yahoo.co.jp",
"GET",
"http",
":path",
"/images/top/sp2/cmn/logo-ns-130528.png",
"example.com",
"hpack-test",
"xxxxxxx1",
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:16.0) Gecko/20100101 Firefox/16.0",
"accept",
"Accept",
"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
"cookie",
"B=76j09a189a6h4&b=3&s=0b",
"TE",
"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi non bibendum libero. \
Etiam ultrices lorem ut.",
];
for s in DATA {
let mut dst = BytesMut::with_capacity(s.len());
encode(s.as_bytes(), &mut dst);
let decoded = decode(&dst).unwrap();
assert_eq!(&decoded[..], s.as_bytes());
}
}
#[test]
fn encode_decode_u8() {
const DATA: &'static [&'static [u8]] =
&[b"\0", b"\0\0\0", b"\0\x01\x02\x03\x04\x05", b"\xFF\xF8"];
for s in DATA {
let mut dst = BytesMut::with_capacity(s.len());
encode(s, &mut dst);
let decoded = decode(&dst).unwrap();
assert_eq!(&decoded[..], &s[..]);
}
}
}
|