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import zlib
from scrapy.utils.gz import gunzip
from scrapy.http import Response, TextResponse
from scrapy.responsetypes import responsetypes
from scrapy.exceptions import NotConfigured
ACCEPTED_ENCODINGS = [b'gzip', b'deflate']
try:
import brotli
ACCEPTED_ENCODINGS.append(b'br')
except ImportError:
pass
class HttpCompressionMiddleware(object):
"""This middleware allows compressed (gzip, deflate) traffic to be
sent/received from web sites"""
@classmethod
def from_crawler(cls, crawler):
if not crawler.settings.getbool('COMPRESSION_ENABLED'):
raise NotConfigured
return cls()
def process_request(self, request, spider):
request.headers.setdefault('Accept-Encoding',
b",".join(ACCEPTED_ENCODINGS))
def process_response(self, request, response, spider):
if request.method == 'HEAD':
return response
if isinstance(response, Response):
content_encoding = response.headers.getlist('Content-Encoding')
if content_encoding:
encoding = content_encoding.pop()
decoded_body = self._decode(response.body, encoding.lower())
respcls = responsetypes.from_args(headers=response.headers, \
url=response.url, body=decoded_body)
kwargs = dict(cls=respcls, body=decoded_body)
if issubclass(respcls, TextResponse):
# force recalculating the encoding until we make sure the
# responsetypes guessing is reliable
kwargs['encoding'] = None
response = response.replace(**kwargs)
if not content_encoding:
del response.headers['Content-Encoding']
return response
def _decode(self, body, encoding):
if encoding == b'gzip' or encoding == b'x-gzip':
body = gunzip(body)
if encoding == b'deflate':
try:
body = zlib.decompress(body)
except zlib.error:
# ugly hack to work with raw deflate content that may
# be sent by microsoft servers. For more information, see:
# http://carsten.codimi.de/gzip.yaws/
# http://www.port80software.com/200ok/archive/2005/10/31/868.aspx
# http://www.gzip.org/zlib/zlib_faq.html#faq38
body = zlib.decompress(body, -15)
if encoding == b'br' and b'br' in ACCEPTED_ENCODINGS:
body = brotli.decompress(body)
return body
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