diff --git a/scrapy/resolver.py b/scrapy/resolver.py index f191deac6..0bef555a6 100644 --- a/scrapy/resolver.py +++ b/scrapy/resolver.py @@ -1,6 +1,6 @@ from twisted.internet import defer from twisted.internet.base import ThreadedResolver -from twisted.internet.interfaces import IHostnameResolver, IResolutionReceiver, IResolverSimple +from twisted.internet.interfaces import IHostResolution, IHostnameResolver, IResolutionReceiver, IResolverSimple from zope.interface.declarations import implementer, provider from scrapy.utils.datatypes import LocalCache @@ -50,6 +50,36 @@ class CachingThreadedResolver(ThreadedResolver): return result +@implementer(IHostResolution) +class HostResolution: + def __init__(self, name): + self.name = name + + def cancel(self): + raise NotImplementedError() + + +@provider(IResolutionReceiver) +class _CachingResolutionReceiver: + def __init__(self, resolutionReceiver, hostName): + self.resolutionReceiver = resolutionReceiver + self.hostName = hostName + self.addresses = [] + + def resolutionBegan(self, resolution): + self.resolutionReceiver.resolutionBegan(resolution) + self.resolution = resolution + + def addressResolved(self, address): + self.resolutionReceiver.addressResolved(address) + self.addresses.append(address) + + def resolutionComplete(self): + self.resolutionReceiver.resolutionComplete() + if self.addresses: + dnscache[self.hostName] = self.addresses + + @implementer(IHostnameResolver) class CachingHostnameResolver: """ @@ -73,33 +103,22 @@ class CachingHostnameResolver: def install_on_reactor(self): self.reactor.installNameResolver(self) - def resolveHostName(self, resolutionReceiver, hostName, portNumber=0, - addressTypes=None, transportSemantics='TCP'): - - @provider(IResolutionReceiver) - class CachingResolutionReceiver(resolutionReceiver): - - def resolutionBegan(self, resolution): - super().resolutionBegan(resolution) - self.resolution = resolution - self.resolved = False - - def addressResolved(self, address): - super().addressResolved(address) - self.resolved = True - - def resolutionComplete(self): - super().resolutionComplete() - if self.resolved: - dnscache[hostName] = self.resolution - + def resolveHostName( + self, resolutionReceiver, hostName, portNumber=0, addressTypes=None, transportSemantics="TCP" + ): try: - return dnscache[hostName] + addresses = dnscache[hostName] except KeyError: return self.original_resolver.resolveHostName( - CachingResolutionReceiver(), + _CachingResolutionReceiver(resolutionReceiver, hostName), hostName, portNumber, addressTypes, - transportSemantics + transportSemantics, ) + else: + resolutionReceiver.resolutionBegan(HostResolution(hostName)) + for addr in addresses: + resolutionReceiver.addressResolved(addr) + resolutionReceiver.resolutionComplete() + return resolutionReceiver diff --git a/tests/CrawlerProcess/alternative_name_resolver.py b/tests/CrawlerProcess/alternative_name_resolver.py deleted file mode 100644 index 2c466da04..000000000 --- a/tests/CrawlerProcess/alternative_name_resolver.py +++ /dev/null @@ -1,15 +0,0 @@ -import scrapy -from scrapy.crawler import CrawlerProcess - - -class IPv6Spider(scrapy.Spider): - name = "ipv6_spider" - start_urls = ["http://[::1]"] - - -process = CrawlerProcess(settings={ - "RETRY_ENABLED": False, - "DNS_RESOLVER": "scrapy.resolver.CachingHostnameResolver", -}) -process.crawl(IPv6Spider) -process.start() diff --git a/tests/CrawlerProcess/caching_hostname_resolver.py b/tests/CrawlerProcess/caching_hostname_resolver.py new file mode 100644 index 000000000..f9eab3543 --- /dev/null +++ b/tests/CrawlerProcess/caching_hostname_resolver.py @@ -0,0 +1,30 @@ +import sys + +import scrapy +from scrapy.crawler import CrawlerProcess + + +class CachingHostnameResolverSpider(scrapy.Spider): + """ + Finishes in a finite amount of time (does not hang indefinitely in the DNS resolution) + """ + name = "caching_hostname_resolver_spider" + + def start_requests(self): + yield scrapy.Request(self.url) + + def parse(self, response): + for _ in range(10): + yield scrapy.Request(response.url, dont_filter=True, callback=self.ignore_response) + + def ignore_response(self, response): + self.logger.info(repr(response.ip_address)) + + +if __name__ == "__main__": + process = CrawlerProcess(settings={ + "RETRY_ENABLED": False, + "DNS_RESOLVER": "scrapy.resolver.CachingHostnameResolver", + }) + process.crawl(CachingHostnameResolverSpider, url=sys.argv[1]) + process.start() diff --git a/tests/CrawlerProcess/caching_hostname_resolver_ipv6.py b/tests/CrawlerProcess/caching_hostname_resolver_ipv6.py new file mode 100644 index 000000000..3340d2f84 --- /dev/null +++ b/tests/CrawlerProcess/caching_hostname_resolver_ipv6.py @@ -0,0 +1,19 @@ +import scrapy +from scrapy.crawler import CrawlerProcess + + +class CachingHostnameResolverSpider(scrapy.Spider): + """ + Finishes without a twisted.internet.error.DNSLookupError exception + """ + name = "caching_hostname_resolver_spider" + start_urls = ["http://[::1]"] + + +if __name__ == "__main__": + process = CrawlerProcess(settings={ + "RETRY_ENABLED": False, + "DNS_RESOLVER": "scrapy.resolver.CachingHostnameResolver", + }) + process.crawl(CachingHostnameResolverSpider) + process.start() diff --git a/tests/CrawlerProcess/default_name_resolver.py b/tests/CrawlerProcess/default_name_resolver.py index 60d91b68b..05a98fbec 100644 --- a/tests/CrawlerProcess/default_name_resolver.py +++ b/tests/CrawlerProcess/default_name_resolver.py @@ -3,10 +3,15 @@ from scrapy.crawler import CrawlerProcess class IPv6Spider(scrapy.Spider): + """ + Raises a twisted.internet.error.DNSLookupError: + the default name resolver does not handle IPv6 addresses. + """ name = "ipv6_spider" start_urls = ["http://[::1]"] -process = CrawlerProcess(settings={"RETRY_ENABLED": False}) -process.crawl(IPv6Spider) -process.start() +if __name__ == "__main__": + process = CrawlerProcess(settings={"RETRY_ENABLED": False}) + process.crawl(IPv6Spider) + process.start() diff --git a/tests/test_crawler.py b/tests/test_crawler.py index 85035a220..b6de33189 100644 --- a/tests/test_crawler.py +++ b/tests/test_crawler.py @@ -22,6 +22,8 @@ from scrapy.extensions.throttle import AutoThrottle from scrapy.extensions import telnet from scrapy.utils.test import get_testenv +from tests.mockserver import MockServer + class BaseCrawlerTest(unittest.TestCase): @@ -280,9 +282,9 @@ class CrawlerRunnerHasSpider(unittest.TestCase): class ScriptRunnerMixin: - def run_script(self, script_name): + def run_script(self, script_name, *script_args): script_path = os.path.join(self.script_dir, script_name) - args = (sys.executable, script_path) + args = [sys.executable, script_path] + list(script_args) p = subprocess.Popen(args, env=get_testenv(), stdout=subprocess.PIPE, stderr=subprocess.PIPE) stdout, stderr = p.communicate() @@ -321,11 +323,20 @@ class CrawlerProcessSubprocess(ScriptRunnerMixin, unittest.TestCase): "twisted.internet.error.DNSLookupError: DNS lookup failed: no results for hostname lookup: ::1.", log) - def test_ipv6_alternative_name_resolver(self): - log = self.run_script('alternative_name_resolver.py') - self.assertIn('Spider closed (finished)', log) + def test_caching_hostname_resolver_ipv6(self): + log = self.run_script("caching_hostname_resolver_ipv6.py") + self.assertIn("Spider closed (finished)", log) self.assertNotIn("twisted.internet.error.DNSLookupError", log) + def test_caching_hostname_resolver_finite_execution(self): + with MockServer() as mock_server: + http_address = mock_server.http_address.replace("0.0.0.0", "127.0.0.1") + log = self.run_script("caching_hostname_resolver.py", http_address) + self.assertIn("Spider closed (finished)", log) + self.assertNotIn("ERROR: Error downloading", log) + self.assertNotIn("TimeoutError", log) + self.assertNotIn("twisted.internet.error.DNSLookupError", log) + def test_reactor_select(self): log = self.run_script("twisted_reactor_select.py") self.assertIn("Spider closed (finished)", log)