pythontwisted框架HttpClient访问代理吗？

Question

我需要使用访问网页

twisted.web.client.getPage()

或类似的方法从已知地址（即：www.google.com）下载网页，问题是：我位于代理服务器后面，我找不到任何有关如何下载网页的说明配置扭曲或工厂来使用我的代理，有什么想法吗？

请记住，我必须指定用户、密码、主机和端口。 在我的 Linux 机器上，我将 http_proxy 和 https_proxy 设置为 http://user:pwd@ip:port

提前谢谢。

Answer 1

from twisted.internet import reactor
from twisted.web import client

def processResult(page):
    print "I got some data", repr(page)
    reactor.callLater(0.1, reactor.stop)
def dealWithError(err):
    print err.getErrorMessage()
    reactor.callLater(0.1, reactor.stop)

class ProxyClientFactory(client.HTTPClientFactory):
    def setURL(self, url):
        client.HTTPClientFactory.setURL(self, url)
        self.path = url

factory = ProxyClientFactory('http://url_you_want')
factory.deferred.addCallbacks(processResult, dealWithError)

reactor.connectTCP('proxy_address', 3142, factory)
reactor.run()

Answer 2

为了让 nosklo 的解决方案发挥作用，您需要为“401”创建另一个处理程序，以指示需要身份验证。尝试这样的操作

def checkAuthError(self,failure,url):
    failure.trap(error.Error)
    if failure.value.status == '401':
        username = raw_input("User name: ")
        password = getpass.getpass("Password: ")
        auth = base64.encodestring("%s:%s" %(username, password))
        header = "Basic " + auth.strip()
        return client.getPage(
            url, headers={"Authorization": header})
    else:
        return failure

这将提示操作员在命令行提供信息，或者您可以以您选择的其他方式提供用户名和密码。确保这是作为 Errback 添加的第一个处理程序，然后再添加任何其他处理程序（甚至是 Callback）。这还需要更多的进口； 'base64'、'getpass' 和 'error' 与命令行提示一起使用。

Answer 3

我必须使用基本身份验证执行类似的操作，因为身份验证请求的示例代码在这里不起作用，但可以使用的版本是：

import base64

from twisted.internet import defer, reactor
from twisted.web import client, error, http

from ubuntuone.devtools.testcases.squid import SquidTestCase

# ignore common twisted lint errors
# pylint: disable=C0103, W0212


class ProxyClientFactory(client.HTTPClientFactory):
    """Factory that supports proxy."""

    def __init__(self, proxy_url, proxy_port, url, headers=None):
        self.proxy_url = proxy_url
        self.proxy_port = proxy_port
        client.HTTPClientFactory.__init__(self, url, headers=headers)

    def setURL(self, url):
        self.host = self.proxy_url
        self.port = self.proxy_port
        self.url = url
        self.path = url


class ProxyWebClient(object):
    """Provide useful web methods with proxy."""

    def __init__(self, proxy_url=None, proxy_port=None, username=None,
            password=None):
        """Create a new instance with the proxy settings."""
        self.proxy_url = proxy_url
        self.proxy_port = proxy_port
        self.username = username
        self.password = password

    def _process_auth_error(self, failure, url, contextFactory):
        """Process an auth failure."""
        # we try to get the page using the basic auth
        failure.trap(error.Error)
        if failure.value.status == str(http.PROXY_AUTH_REQUIRED):
            auth = base64.b64encode('%s:%s' % (self.username, self.password))
            auth_header = 'Basic ' + auth.strip()
            factory = ProxyClientFactory(self.proxy_url, self.proxy_port, url,
                    headers={'Proxy-Authorization': auth_header})
            # pylint: disable=E1101
            reactor.connectTCP(self.proxy_url, self.proxy_port, factory)
            # pylint: enable=E1101
            return factory.deferred
        else:
            return failure

    def get_page(self, url, contextFactory=None, *args, **kwargs):
        """Download a webpage as a string.

        This method relies on the twisted.web.client.getPage but adds and extra
        step. If there is an auth error the method will perform a second try
        so that the username and password are used.
        """
        scheme, _, _, _ = client._parse(url)
        factory = ProxyClientFactory(self.proxy_url, self.proxy_port, url)
        if scheme == 'https':
            from twisted.internet import ssl
            if contextFactory is None:
                contextFactory = ssl.ClientContextFactory()
            # pylint: disable=E1101
            reactor.connectSSL(self.proxy_url, self.proxy_port,
                               factory, contextFactory)
            # pylint: enable=E1101
        else:
            # pylint: disable=E1101
            reactor.connectTCP(self.proxy_url, self.proxy_port, factory)
            # pylint: enable=E1101
        factory.deferred.addErrback(self._process_auth_error, url,
                                    contextFactory)
        return factory.deferred

Answer 4

我们选择使用 http_proxy 环境变量。我们遇到了重定向问题，重定向并不总是被接收，或者更确切地说是以正确的方式被接收。也就是说，nosklo 的回应确实很有帮助！

import os
from twisted.web import client

class ProxyClientFactory(client.HTTPClientFactory):
    def setURL(self, url):
        '''More sensitive to redirects that can happen, that
        may or may not be proxied / have different proxy settings.'''
        scheme, host, port, path = client._parse(url)
        proxy = os.environ.get('%s_proxy' % scheme)
        if proxy:
            scheme, host, port, path = client._parse(proxy)
            self.scheme = scheme
            self.host = host
            self.port = port
            self.path = url
            self.url = url
        else:
            client.HTTPClientFactory.setURL(self, url)

factory = ProxyClientFactory(url)
# Callback configuration
# If http_proxy or https_proxy, or whatever appropriate proxy
# is set, then we should try to honor that. We do so simply 
# by overriding the host/port we'll connect to. The client
# factory, BaseRequestServicer takes care of the rest
scheme, host, port, path = client._parse(url)
proxy = os.environ.get('%s_proxy' % scheme)
if proxy:
    scheme, host, port, path = client._parse(proxy)
reactor.connectTCP(host, port, factory)