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"""
This is a middleware to respect robots.txt policies. To activate it you must
enable this middleware and enable the ROBOTSTXT_OBEY setting.
"""
import logging
from twisted.internet.defer import Deferred, maybeDeferred
from scrapy.exceptions import NotConfigured, IgnoreRequest
from scrapy.http import Request
from scrapy.utils.httpobj import urlparse_cached
from scrapy.utils.log import failure_to_exc_info
from scrapy.utils.misc import load_object
logger = logging.getLogger(__name__)
class RobotsTxtMiddleware:
DOWNLOAD_PRIORITY = 1000
def __init__(self, crawler):
if not crawler.settings.getbool('ROBOTSTXT_OBEY'):
raise NotConfigured
self._default_useragent = crawler.settings.get('USER_AGENT', 'Scrapy')
self._robotstxt_useragent = crawler.settings.get('ROBOTSTXT_USER_AGENT', None)
self.crawler = crawler
self._parsers = {}
self._parserimpl = load_object(crawler.settings.get('ROBOTSTXT_PARSER'))
# check if parser dependencies are met, this should throw an error otherwise.
self._parserimpl.from_crawler(self.crawler, b'')
@classmethod
def from_crawler(cls, crawler):
return cls(crawler)
def process_request(self, request, spider):
if request.meta.get('dont_obey_robotstxt'):
return
d = maybeDeferred(self.robot_parser, request, spider)
d.addCallback(self.process_request_2, request, spider)
return d
def process_request_2(self, rp, request, spider):
if rp is None:
return
useragent = self._robotstxt_useragent
if not useragent:
useragent = request.headers.get(b'User-Agent', self._default_useragent)
if not rp.allowed(request.url, useragent):
logger.debug("Forbidden by robots.txt: %(request)s",
{'request': request}, extra={'spider': spider})
self.crawler.stats.inc_value('robotstxt/forbidden')
raise IgnoreRequest("Forbidden by robots.txt")
def robot_parser(self, request, spider):
url = urlparse_cached(request)
netloc = url.netloc
if netloc not in self._parsers:
self._parsers[netloc] = Deferred()
robotsurl = f"{url.scheme}://{url.netloc}/robots.txt"
robotsreq = Request(
robotsurl,
priority=self.DOWNLOAD_PRIORITY,
meta={'dont_obey_robotstxt': True}
)
dfd = self.crawler.engine.download(robotsreq, spider)
dfd.addCallback(self._parse_robots, netloc, spider)
dfd.addErrback(self._logerror, robotsreq, spider)
dfd.addErrback(self._robots_error, netloc)
self.crawler.stats.inc_value('robotstxt/request_count')
if isinstance(self._parsers[netloc], Deferred):
d = Deferred()
def cb(result):
d.callback(result)
return result
self._parsers[netloc].addCallback(cb)
return d
else:
return self._parsers[netloc]
def _logerror(self, failure, request, spider):
if failure.type is not IgnoreRequest:
logger.error("Error downloading %(request)s: %(f_exception)s",
{'request': request, 'f_exception': failure.value},
exc_info=failure_to_exc_info(failure),
extra={'spider': spider})
return failure
def _parse_robots(self, response, netloc, spider):
self.crawler.stats.inc_value('robotstxt/response_count')
self.crawler.stats.inc_value(f'robotstxt/response_status_count/{response.status}')
rp = self._parserimpl.from_crawler(self.crawler, response.body)
rp_dfd = self._parsers[netloc]
self._parsers[netloc] = rp
rp_dfd.callback(rp)
def _robots_error(self, failure, netloc):
if failure.type is not IgnoreRequest:
key = f'robotstxt/exception_count/{failure.type}'
self.crawler.stats.inc_value(key)
rp_dfd = self._parsers[netloc]
self._parsers[netloc] = None
rp_dfd.callback(None)
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