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###############################################################################
# libproxy - A library for proxy configuration
# Copyright (C) 2006 Nathaniel McCallum <nathaniel@natemccallum.com>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
###############################################################################
"A library for proxy configuration and autodetection."
import ctypes
import ctypes.util
import platform
import sys
# Load C library
if platform.system() == "Windows":
_libc = ctypes.cdll.msvcrt
else:
if not ctypes.util.find_library("c"):
raise ImportError("Unable to import C Library!?!")
_libc = ctypes.cdll.LoadLibrary(ctypes.util.find_library("c"))
# Load libproxy
if not ctypes.util.find_library("proxy"):
raise ImportError("Unable to import libproxy!?!?")
_libproxy = ctypes.cdll.LoadLibrary(ctypes.util.find_library("proxy"))
_libproxy.px_proxy_factory_get_proxies.restype = ctypes.POINTER(ctypes.c_void_p)
class ProxyFactory(object):
"""A ProxyFactory object is used to provide potential proxies to use
in order to reach a given URL (via 'getProxies(url)').
This instance should be kept around as long as possible as it contains
cached data to increase performance. Memory usage should be minimal (cache
is small) and the cache lifespan is handled automatically.
Usage is pretty simple:
pf = libproxy.ProxyFactory()
for url in urls:
proxies = pf.getProxies(url)
for proxy in proxies:
if proxy == "direct://":
# Fetch URL without using a proxy
elif proxy.startswith("http://"):
# Fetch URL using an HTTP proxy
elif proxy.startswith("socks://"):
# Fetch URL using a SOCKS proxy
if fetchSucceeded:
break
"""
class ProxyResolutionError(RuntimeError):
"""Exception raised when proxy cannot be resolved generally
due to invalid URL"""
pass
def __init__(self):
self._pf = _libproxy.px_proxy_factory_new()
def getProxies(self, url):
"""Given a URL, returns a list of proxies in priority order to be used
to reach that URL.
A list of proxy strings is returned. If the first proxy fails, the
second should be tried, etc... In all cases, at least one entry in the
list will be returned. There are no error conditions.
Regarding performance: this method always blocks and may be called
in a separate thread (is thread-safe). In most cases, the time
required to complete this function call is simply the time required
to read the configuration (e.g from GConf, Kconfig, etc).
In the case of PAC, if no valid PAC is found in the cache (i.e.
configuration has changed, cache is invalid, etc), the PAC file is
downloaded and inserted into the cache. This is the most expensive
operation as the PAC is retrieved over the network. Once a PAC exists
in the cache, it is merely a JavaScript invocation to evaluate the PAC.
One should note that DNS can be called from within a PAC during
JavaScript invocation.
In the case of WPAD, WPAD is used to automatically locate a PAC on the
network. Currently, we only use DNS for this, but other methods may
be implemented in the future. Once the PAC is located, normal PAC
performance (described above) applies.
"""
if type(url) != str:
raise TypeError("url must be a string!")
proxies = []
array = _libproxy.px_proxy_factory_get_proxies(self._pf, url)
if not bool(array):
raise ProxyFactory.ProxyResolutionError(
"Can't resolve proxy for '%s'" % url)
i=0
while array[i]:
proxies.append(str(ctypes.cast(array[i], ctypes.c_char_p).value))
_libc.free(array[i])
i += 1
_libc.free(array)
return proxies
def __del__(self):
_libproxy.px_proxy_factory_free(self._pf)
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