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from urlparse import urljoin
from scrapy import log
from scrapy.http import HtmlResponse
from scrapy.utils.response import get_meta_refresh
from scrapy.exceptions import IgnoreRequest, NotConfigured
from scrapy.conf import settings
class RedirectMiddleware(object):
"""Handle redirection of requests based on response status and meta-refresh html tag"""
def __init__(self):
15 if not settings.getbool('REDIRECT_ENABLED'):
raise NotConfigured
self.max_metarefresh_delay = settings.getint('REDIRECT_MAX_METAREFRESH_DELAY')
self.max_redirect_times = settings.getint('REDIRECT_MAX_TIMES')
self.priority_adjust = settings.getint('REDIRECT_PRIORITY_ADJUST')
def process_response(self, request, response, spider):
if 'dont_redirect' in request.meta:
return response
if request.method.upper() == 'HEAD':
if response.status in [301, 302, 303, 307] and 'Location' in response.headers:
redirected_url = urljoin(request.url, response.headers['location'])
redirected = request.replace(url=redirected_url)
return self._redirect(redirected, request, spider, response.status)
else:
return response
if response.status in [302, 303] and 'Location' in response.headers:
redirected_url = urljoin(request.url, response.headers['location'])
redirected = self._redirect_request_using_get(request, redirected_url)
return self._redirect(redirected, request, spider, response.status)
if response.status in [301, 307] and 'Location' in response.headers:
redirected_url = urljoin(request.url, response.headers['location'])
redirected = request.replace(url=redirected_url)
return self._redirect(redirected, request, spider, response.status)
if isinstance(response, HtmlResponse):
interval, url = get_meta_refresh(response)
if url and interval < self.max_metarefresh_delay:
redirected = self._redirect_request_using_get(request, url)
return self._redirect(redirected, request, spider, 'meta refresh')
return response
def _redirect(self, redirected, request, spider, reason):
ttl = request.meta.setdefault('redirect_ttl', self.max_redirect_times)
redirects = request.meta.get('redirect_times', 0) + 1
if ttl and redirects <= self.max_redirect_times:
redirected.meta['redirect_times'] = redirects
redirected.meta['redirect_ttl'] = ttl - 1
redirected.meta['redirect_urls'] = request.meta.get('redirect_urls', []) + \
[request.url]
redirected.dont_filter = request.dont_filter
redirected.priority = request.priority + self.priority_adjust
log.msg("Redirecting (%s) to %s from %s" % (reason, redirected, request),
spider=spider, level=log.DEBUG)
return redirected
else:
log.msg("Discarding %s: max redirections reached" % request,
spider=spider, level=log.DEBUG)
raise IgnoreRequest
def _redirect_request_using_get(self, request, redirect_url):
redirected = request.replace(url=redirect_url, method='GET', body='')
redirected.headers.pop('Content-Type', None)
redirected.headers.pop('Content-Length', None)
return redirected
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