from __future__ import annotations
import logging
import re
from typing import TYPE_CHECKING
from scrapy import Request, Spider, signals
from scrapy.exceptions import IgnoreRequest
from scrapy.utils.decorators import _warn_spider_arg
from scrapy.utils.httpobj import urlparse_cached
if TYPE_CHECKING:
# typing.Self requires Python 3.11
from typing_extensions import Self
from scrapy.crawler import Crawler
from scrapy.statscollectors import StatsCollector
logger = logging.getLogger(__name__)
[docs]
class OffsiteMiddleware:
"""Filter out requests for URLs outside the domains covered by the spider.
.. versionadded:: 2.11.2
A request is allowed if its host name is in the
:attr:`~scrapy.Spider.allowed_domains` attribute of the spider, or is a
subdomain of one of those domains. E.g. ``www.example.org`` also allows
``bob.www.example.org``, but neither ``www2.example.org`` nor
``example.org``. See :meth:`should_follow` to use a different policy.
If the spider does not define :attr:`~scrapy.Spider.allowed_domains`, or
the attribute is empty, every request is allowed.
Filtered requests are logged as follows::
DEBUG: Filtered offsite request to 'offsite.example': <GET http://offsite.example/some/page.html>
Only the first request filtered for a given domain is logged, to keep the
log readable.
.. reqmeta:: allow_offsite
allow_offsite
-------------
Requests with the ``allow_offsite`` :attr:`~scrapy.Request.meta` key set to
``True``, or with :attr:`~scrapy.Request.dont_filter` set to ``True``, are
allowed regardless of their host name.
"""
crawler: Crawler
host_regex: re.Pattern[str]
def __init__(self, stats: StatsCollector):
self.stats = stats
self.domains_seen: set[str] = set()
self._allowed_domains: list[str] | None = None
@classmethod
def from_crawler(cls, crawler: Crawler) -> Self:
o = cls(crawler.stats)
crawler.signals.connect(o.spider_opened, signal=signals.spider_opened)
crawler.signals.connect(o.request_scheduled, signal=signals.request_scheduled)
o.crawler = crawler
return o
def spider_opened(self, spider: Spider) -> None:
self._update_host_regex(spider)
def _update_host_regex(self, spider: Spider) -> None:
allowed_domains = list(getattr(spider, "allowed_domains", None) or [])
if allowed_domains != self._allowed_domains:
self._allowed_domains = allowed_domains
self.host_regex = self.get_host_regex(spider)
def request_scheduled(self, request: Request, spider: Spider) -> None:
self.process_request(request)
@_warn_spider_arg
def process_request(self, request: Request, spider: Spider | None = None) -> None:
assert self.crawler.spider
if (
request.dont_filter
or request.meta.get("allow_offsite")
or self.should_follow(request, self.crawler.spider)
):
return
domain = urlparse_cached(request).hostname
if domain and domain not in self.domains_seen:
self.domains_seen.add(domain)
logger.debug(
"Filtered offsite request to %(domain)r: %(request)s",
{"domain": domain, "request": request},
extra={"spider": self.crawler.spider},
)
self.stats.inc_value("offsite/domains")
self.stats.inc_value("offsite/filtered")
raise IgnoreRequest(f"Filtered offsite request to {domain!r}")
[docs]
def should_follow(self, request: Request, spider: Spider) -> bool:
"""Return ``True`` if *request* is on site, ``False`` if it must be
filtered out.
Override this method to implement a different offsite policy. For
example, to allow the domains in
:attr:`~scrapy.Spider.allowed_domains` but none of their subdomains:
.. code-block:: python
from scrapy.downloadermiddlewares.offsite import OffsiteMiddleware
from scrapy.utils.httpobj import urlparse_cached
class RootOnlyOffsiteMiddleware(OffsiteMiddleware):
def should_follow(self, request, spider):
return urlparse_cached(request).hostname in spider.allowed_domains
"""
self._update_host_regex(spider)
regex = self.host_regex
# hostname can be None for wrong urls (like javascript links)
host = urlparse_cached(request).hostname or ""
return bool(regex.search(host))
def get_host_regex(self, spider: Spider) -> re.Pattern[str]:
allowed_domains = getattr(spider, "allowed_domains", None)
if not allowed_domains:
return re.compile("") # allow all by default
domains = []
for domain in allowed_domains:
if domain is None:
continue
domains.append(re.escape(domain))
regex = rf"^(.*\.)?({'|'.join(domains)})$"
return re.compile(regex)