Question

我一直在运行此代码（来自：http://blog.somethingaboutcode.com/?p=155）：

from twisted.internet import reactor
from twisted.web import http
from twisted.web.proxy import Proxy, ProxyRequest, ProxyClientFactory, ProxyClient
from ImageFile import Parser
from StringIO import StringIO

class InterceptingProxyClient(ProxyClient):
    def __init__(self, *args, **kwargs):
        ProxyClient.__init__(self, *args, **kwargs)
        self.image_parser = None

    def handleHeader(self, key, value):
        if key == "Content-Type" and value in ["image/jpeg", "image/gif", "image/png"]:
            self.image_parser = Parser()
        if key == "Content-Length" and self.image_parser:
            pass
        else:
            ProxyClient.handleHeader(self, key, value)

    def handleEndHeaders(self):
        if self.image_parser:
            pass #Need to calculate and send Content-Length first
        else:
            ProxyClient.handleEndHeaders(self)

    def handleResponsePart(self, buffer):
        print buffer
        if self.image_parser:
            self.image_parser.feed(buffer)
        else:
            ProxyClient.handleResponsePart(self, buffer)

    def handleResponseEnd(self):
        if self.image_parser:
            image = self.image_parser.close()
            try:
                format = image.format
                image = image.rotate(180)
                s = StringIO()
                image.save(s, format)
                buffer = s.getvalue()
            except:
                buffer = ""
            ProxyClient.handleHeader(self, "Content-Length", len(buffer))
            ProxyClient.handleEndHeaders(self)
            ProxyClient.handleResponsePart(self, buffer)
        ProxyClient.handleResponseEnd(self)

class InterceptingProxyClientFactory(ProxyClientFactory):
    protocol = InterceptingProxyClient

class InterceptingProxyRequest(ProxyRequest):
    protocols = {'http': InterceptingProxyClientFactory}
    ports = {"http" : 80}

class InterceptingProxy(Proxy):
    requestFactory = InterceptingProxyRequest

factory = http.HTTPFactory()
factory.protocol = InterceptingProxy

reactor.listenTCP(8000, factory)
reactor.run()

每当我得到这个并转到127.0.0.1:8000，我得到这个：

Traceback (most recent call last):
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\python\log.py",
line 84, in callWithLogger
    return callWithContext({"system": lp}, func, *args, **kw)
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\python\log.py",
line 69, in callWithContext
    return context.call({ILogContext: newCtx}, func, *args, **kw)
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\python\context.p
y", line 59, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\python\context.p
y", line 37, in callWithContext
    return func(*args,**kw)
--- <exception caught here> ---
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\internet\selectr
eactor.py", line 146, in _doReadOrWrite
    why = getattr(selectable, method)()
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\internet\tcp.py"
, line 460, in doRead
    return self.protocol.dataReceived(data)
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\protocols\basic.
py", line 251, in dataReceived
    why = self.lineReceived(line)
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\web\http.py", li
ne 1573, in lineReceived
    self.allContentReceived()
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\web\http.py", li
ne 1641, in allContentReceived
    req.requestReceived(command, path, version)
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\web\http.py", li
ne 807, in requestReceived
    self.process()
  File "C:\Program Files\Python 2.6.2\lib\site-packages\twisted\web\proxy.py", l
ine 147, in process
    port = self.ports[protocol]
exceptions.KeyError: ''

每当我设置firefox或chrome或opera以使用localhost：8000上的代理时，没有与代理建立连接（我不能再连接到任何页面，尽管这可能是因为它没有连接到代理）。

好吧它仍然失败并且通过日志记录我得到这个输出当我设置firefox在localhost：8000使用代理并且不直接从Web浏览器访问代理（例如在firefox的地址栏中键入localhost：8000））

2010-08-04 12:31:18-0400 [-] Log opened.
2010-08-04 12:31:29-0400 [-] twisted.web.http.HTTPFactory starting on 8000
2010-08-04 12:31:29-0400 [-] Starting factory <twisted.web.http.HTTPFactory inst
ance at 0x010B3EE0>
2010-08-04 12:33:55-0400 [-] Received SIGINT, shutting down.
2010-08-04 12:33:55-0400 [twisted.web.http.HTTPFactory] (Port 8000 Closed)
2010-08-04 12:33:55-0400 [twisted.web.http.HTTPFactory] Stopping factory <twiste
d.web.http.HTTPFactory instance at 0x010B3EE0>
2010-08-04 12:33:55-0400 [-] Main loop terminated.

然而，当我直接访问代理时，我收到了密钥错误。

另外，对于嗅闻我不能; Wireshark似乎没有嗅探本地主机流量，如果我使用fiddler 2它将自己设置为代理（因此我不再使用我的代理服务器）然后工作（因为它使用fiddler 2的代理）。

Answer 1

直接连接时看到的KeyError异常是由于对代理的请求必须包含绝对URL而不是相对URL。如果您的浏览器不知道它正在与代理通话，它将请求/foo/bar之类的网址。如果它确实知道它正在与代理进行通信，那么它将请求http://example.com/foo/bar之类的内容。 http://example.com/部分很重要，因为它是代理知道它应该关闭和检索的唯一方式。

至于为什么Firefox，Chrome和Opera都没有连接到代理，一旦你配置它们，这有点难以解释。确保您正在配置“HTTP代理”，而不是任何其他支持的代理。一旦你仔细检查过，你可能想要使用像Wireshark这样的工具来更好地了解网络层上发生的事情。

可能是连接真正发生在代理上，但是其他一些错误导致它们无法完成。在这种情况下，如果未启用日志记录，您可能无法通过查看其输出来告知代理正在接收连接。要启用日志记录，请尝试：

from sys import stdout
from twisted.python.log import startLogging
startLogging(stdout)

扭曲的Web代理

1 个答案: