Solution for XML-RPC over a proxy

[Andrew R]

All,

I couldn't get my xml-rpc script to work via a corporate proxy.

I noticed a few posts asking about this, and a very good helper script by jjk on
starship. That script didn't work for me, and I think its a little old -- but it
was very helpful to figure it out.

The below script is a replacement/update to the earlier work. It is runnable as
a test or usable as a module. Tests pass from behind and away from a proxy, on
win32 and Linux i686, with Python 2.4.1.

Comments welcome.

Regards
Andrew

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#!/bin/env python
"""urllib2-based transport class for xmlrpclib.py (with test code).

Written from scratch but inspired by xmlrpc_urllib_transport.py
file from http://starship.python.net/crew/jjkunce/ by jjk.

A. Ellerton 2006-07-06

Testing with Python 2.4 on Windows and Linux, with/without a corporate
proxy in place.

****************************
*** USE AT YOUR OWN RISK ***
****************************
"""

import xmlrpclib

class ProxyTransport(xmlrpclib.Transport):
	"""Provides an XMl-RPC transport routing via a http proxy.
	
	This is done by using urllib2, which in turn uses the environment
	varable http_proxy and whatever else it is built to use (e.g. the
	windows	registry).
	
	NOTE: the environment variable http_proxy should be set correctly.
	See checkProxySetting() below.
	
	Written from scratch but inspired by xmlrpc_urllib_transport.py
	file from http://starship.python.net/crew/jjkunce/ by jjk.
	
	A. Ellerton 2006-07-06
	"""

	def request(self, host, handler, request_body, verbose):
		import urllib2
		self.verbose=verbose
		url='http://'+host+handler
		if self.verbose: "ProxyTransport URL: [%s]"%url

		request = urllib2.Request(url)
		request.add_data(request_body)
		# Note: 'Host' and 'Content-Length' are added automatically
		request.add_header("User-Agent", self.user_agent)
		request.add_header("Content-Type", "text/xml") # Important

		proxy_handler=urllib2.ProxyHandler()
		opener=urllib2.build_opener(proxy_handler)
		f=opener.open(request)
		return(self.parse_response(f))


def checkProxySetting():
	"""If the variable 'http_proxy' is set, it will most likely be in one
	of these forms (not real host/ports):
	
		  proxyhost:8080
		  http://proxyhost:8080
	
	urlllib2 seems to require it to have 'http;//" at the start.
	This routine does that, and returns the transport for xmlrpc.
	"""
	import os, re
	try:
		http_proxy=os.environ['http_proxy']
	except KeyError:
		return
	
	# ensure the proxy has the 'http://' at the start
	#
	match = re.match("(http://)?([-_\.A-Za-z]+):(\d+)", http_proxy)
	if not match: raise Exception("Proxy format not recognised: [%s]" % http_proxy)
	os.environ['http_proxy'] = "http://%s:%s" % (match.group(2), match.group(3))
	#print "Determined proxy: %s" % os.environ['http_proxy']
	return


def test():
	import sys, os
	
	def nextArg():
		try: return sys.argv.pop(1)
		except: return None

	checkProxySetting()
	
	url=nextArg() or "http://betty.userland.com"
	api=nextArg() or "examples.getStateName(32)" # "examples.getStateList([1,2])"
	try:
		server=xmlrpclib.Server(url, transport=ProxyTransport())
		print "Url: %s" % url
		
		try: print "Proxy: %s" % os.environ['http_proxy']
		except KeyError: print "Proxy: (Apparently none)"
		
		print "API: %s" % api
		r = eval("server.%s"%api)
		print "Result: ", r
		
	except xmlrpclib.ProtocolError, e:
		print "Connection error: %s" % e
	except xmlrpclib.Fault, e:
		print "Error: %s" % e

if __name__=='__main__':
	# run with no parameters for basic test case.
	test()
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