aboutsummaryrefslogtreecommitdiffstats
path: root/netlib/encoding.py
blob: 14479e00c8d144d97b39033b8cd1c9ed35612e78 (plain)
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
"""
    Utility functions for decoding response bodies.
"""
from __future__ import absolute_import
from io import BytesIO
import gzip
import zlib
from .utils import always_byte_args


ENCODINGS = {"identity", "gzip", "deflate"}


def decode(e, content):
    if not isinstance(content, bytes):
        return None
    encoding_map = {
        "identity": identity,
        "gzip": decode_gzip,
        "deflate": decode_deflate,
    }
    if e not in encoding_map:
        return None
    return encoding_map[e](content)


def encode(e, content):
    if not isinstance(content, bytes):
        return None
    encoding_map = {
        "identity": identity,
        "gzip": encode_gzip,
        "deflate": encode_deflate,
    }
    if e not in encoding_map:
        return None
    return encoding_map[e](content)


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))
    try:
        return gfile.read()
    except (IOError, EOFError):
        return None


def encode_gzip(content):
    s = BytesIO()
    gf = gzip.GzipFile(fileobj=s, mode='wb')
    gf.write(content)
    gf.close()
    return s.getvalue()


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:
        try:
            return zlib.decompress(content)
        except zlib.error:
            return zlib.decompress(content, -15)
    except zlib.error:
        return None


def encode_deflate(content):
    """
        Returns compressed content, always including zlib header and checksum.
    """
    return zlib.compress(content)

__all__ = ["ENCODINGS", "encode", "decode"]