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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.
"""
from __future__ import annotations
import logging
from typing import TYPE_CHECKING
from twisted.internet.defer import Deferred, maybeDeferred
from scrapy.exceptions import IgnoreRequest, NotConfigured
from scrapy.http import Request, Response
from scrapy.http.request import NO_CALLBACK
from scrapy.utils.httpobj import urlparse_cached
from scrapy.utils.log import failure_to_exc_info
from scrapy.utils.misc import load_object
if TYPE_CHECKING:
from twisted.python.failure import Failure
# typing.Self requires Python 3.11
from typing_extensions import Self
from scrapy import Spider
from scrapy.crawler import Crawler
from scrapy.robotstxt import RobotParser
logger = logging.getLogger(__name__)
class RobotsTxtMiddleware:
DOWNLOAD_PRIORITY: int = 1000
def __init__(self, crawler: Crawler):
if not crawler.settings.getbool("ROBOTSTXT_OBEY"):
raise NotConfigured
self._default_useragent: str = crawler.settings.get("USER_AGENT", "Scrapy")
self._robotstxt_useragent: str | None = crawler.settings.get(
"ROBOTSTXT_USER_AGENT", None
)
self.crawler: Crawler = crawler
self._parsers: dict[str, RobotParser | Deferred[RobotParser | None] | None] = {}
self._parserimpl: RobotParser = 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: Crawler) -> Self:
return cls(crawler)
def process_request(
self, request: Request, spider: Spider
) -> Deferred[None] | None:
if request.meta.get("dont_obey_robotstxt"):
return None
if request.url.startswith("data:") or request.url.startswith("file:"):
return None
d: Deferred[RobotParser | None] = maybeDeferred(
self.robot_parser,
request,
spider, # type: ignore[call-overload]
)
d2: Deferred[None] = d.addCallback(self.process_request_2, request, spider)
return d2
def process_request_2(
self, rp: RobotParser | None, request: Request, spider: Spider
) -> None:
if rp is None:
return
useragent: str | bytes | None = self._robotstxt_useragent
if not useragent:
useragent = request.headers.get(b"User-Agent", self._default_useragent)
assert useragent is not None
if not rp.allowed(request.url, useragent):
logger.debug(
"Forbidden by robots.txt: %(request)s",
{"request": request},
extra={"spider": spider},
)
assert self.crawler.stats
self.crawler.stats.inc_value("robotstxt/forbidden")
raise IgnoreRequest("Forbidden by robots.txt")
def robot_parser(
self, request: Request, spider: Spider
) -> RobotParser | Deferred[RobotParser | None] | None:
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},
callback=NO_CALLBACK,
)
assert self.crawler.engine
assert self.crawler.stats
dfd = self.crawler.engine.download(robotsreq)
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")
parser = self._parsers[netloc]
if isinstance(parser, Deferred):
d: Deferred[RobotParser | None] = Deferred()
def cb(result: RobotParser | None) -> RobotParser | None:
d.callback(result)
return result
parser.addCallback(cb)
return d
return parser
def _logerror(self, failure: Failure, request: Request, spider: Spider) -> Failure:
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: Response, netloc: str, spider: Spider) -> None:
assert self.crawler.stats
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]
assert isinstance(rp_dfd, Deferred)
self._parsers[netloc] = rp
rp_dfd.callback(rp)
def _robots_error(self, failure: Failure, netloc: str) -> None:
if failure.type is not IgnoreRequest:
key = f"robotstxt/exception_count/{failure.type}"
assert self.crawler.stats
self.crawler.stats.inc_value(key)
rp_dfd = self._parsers[netloc]
assert isinstance(rp_dfd, Deferred)
self._parsers[netloc] = None
rp_dfd.callback(None)
|
