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
|
"""
Utility functions for decoding response bodies.
"""
from __future__ import absolute_import
import codecs
import collections
from io import BytesIO
import gzip
import zlib
import brotli
from typing import Union
# We have a shared single-element cache for encoding and decoding.
# This is quite useful in practice, e.g.
# flow.request.content = flow.request.content.replace(b"foo", b"bar")
# does not require an .encode() call if content does not contain b"foo"
CachedDecode = collections.namedtuple("CachedDecode", "encoded encoding errors decoded")
_cache = CachedDecode(None, None, None, None)
def decode(encoded: Union[str, bytes], encoding: str, errors: str='strict') -> Union[str, bytes]:
"""
Decode the given input object
Returns:
The decoded value
Raises:
ValueError, if decoding fails.
"""
if len(encoded) == 0:
return encoded
global _cache
cached = (
isinstance(encoded, bytes) and
_cache.encoded == encoded and
_cache.encoding == encoding and
_cache.errors == errors
)
if cached:
return _cache.decoded
try:
try:
decoded = custom_decode[encoding](encoded)
except KeyError:
decoded = codecs.decode(encoded, encoding, errors)
if encoding in ("gzip", "deflate", "br"):
_cache = CachedDecode(encoded, encoding, errors, decoded)
return decoded
except TypeError:
raise
except Exception as e:
raise ValueError("{} when decoding {} with {}: {}".format(
type(e).__name__,
repr(encoded)[:10],
repr(encoding),
repr(e),
))
def encode(decoded: Union[str, bytes], encoding: str, errors: str='strict') -> Union[str, bytes]:
"""
Encode the given input object
Returns:
The encoded value
Raises:
ValueError, if encoding fails.
"""
if len(decoded) == 0:
return decoded
global _cache
cached = (
isinstance(decoded, bytes) and
_cache.decoded == decoded and
_cache.encoding == encoding and
_cache.errors == errors
)
if cached:
return _cache.encoded
try:
try:
value = decoded
if isinstance(value, str):
value = decoded.encode()
encoded = custom_encode[encoding](value)
except KeyError:
encoded = codecs.encode(decoded, encoding, errors)
if encoding in ("gzip", "deflate", "br"):
_cache = CachedDecode(encoded, encoding, errors, decoded)
return encoded
except TypeError:
raise
except Exception as e:
raise ValueError("{} when encoding {} with {}: {}".format(
type(e).__name__,
repr(decoded)[:10],
repr(encoding),
repr(e),
))
def identity(content):
"""
Returns content unchanged. Identity is the default value of
Accept-Encoding headers.
"""
return content
def decode_gzip(content):
gfile = gzip.GzipFile(fileobj=BytesIO(content))
return gfile.read()
def encode_gzip(content):
s = BytesIO()
gf = gzip.GzipFile(fileobj=s, mode='wb')
gf.write(content)
gf.close()
return s.getvalue()
def decode_brotli(content):
return brotli.decompress(content)
def encode_brotli(content):
return brotli.compress(content)
def decode_deflate(content):
"""
Returns decompressed data for DEFLATE. Some servers may respond with
compressed data without a zlib header or checksum. An undocumented
feature of zlib permits the lenient decompression of data missing both
values.
http://bugs.python.org/issue5784
"""
try:
return zlib.decompress(content)
except zlib.error:
return zlib.decompress(content, -15)
def encode_deflate(content):
"""
Returns compressed content, always including zlib header and checksum.
"""
return zlib.compress(content)
custom_decode = {
"none": identity,
"identity": identity,
"gzip": decode_gzip,
"deflate": decode_deflate,
"br": decode_brotli,
}
custom_encode = {
"none": identity,
"identity": identity,
"gzip": encode_gzip,
"deflate": encode_deflate,
"br": encode_brotli,
}
__all__ = ["encode", "decode"]
|
