Source code for psychopy.web

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""Library for working with internet connections"""

# Part of the PsychoPy library
# Copyright (C) 2002-2018 Jonathan Peirce (C) 2019-2020 Open Science Tools Ltd.
# Distributed under the terms of the GNU General Public License (GPL).

from __future__ import absolute_import, print_function

# from future import standard_library
# standard_library.install_aliases()

from builtins import object
import sys
import socket
import re
from psychopy import logging
from psychopy.constants import PSYCHOPY_USERAGENT, PY3
from psychopy import prefs


if PY3:
    import urllib.request
    import urllib.error
    import urllib.parse
else:
    import urllib2
    # import urllib.request, urllib.error, urllib.parse

    class FakeURLlib(object):

        def __init__(self, lib):
            self.request = lib
            self.error = lib
            self.parse = lib
    urllib = FakeURLlib(urllib2)

# default 20s from prefs, min 2s
TIMEOUT = max(prefs.connections['timeout'], 2.0)
socket.setdefaulttimeout(TIMEOUT)

# global proxies
proxies = None  # if this is populated then it has been set up already


class NoInternetAccessError(Exception):
    """An internet connection is required but not available
    """
# global haveInternet
haveInternet = None  # gets set True or False when you check


[docs]def haveInternetAccess(forceCheck=False): """Detect active internet connection or fail quickly. If forceCheck is False, will rely on a cached value if possible. """ global haveInternet if forceCheck or haveInternet is None: # try to connect to a high-availability site sites = ["http://www.google.com/", "http://www.opendns.com/"] for wait in [0.3, 0.7]: # try to be quick first for site in sites: try: urllib.request.urlopen(site, timeout=wait) haveInternet = True # cache return True # one success is good enough except Exception: # urllib.error.URLError: # socket.timeout() can also happen pass else: haveInternet = False return haveInternet
[docs]def requireInternetAccess(forceCheck=False): """Checks for access to the internet, raise error if no access. """ if not haveInternetAccess(forceCheck=forceCheck): msg = 'Internet access required but not detected.' logging.error(msg) raise NoInternetAccessError(msg) return True
def tryProxy(handler, URL=None): """ Test whether we can connect to a URL with the current proxy settings. `handler` can be typically `web.proxies`, if `web.setupProxy()` has been run. :Returns: - True (success) - a `urllib.error.URLError` (which can be interrogated with `.reason`) - a `urllib.error.HTTPError` (which can be interrogated with `.code`) """ if URL is None: URL = 'http://www.google.com' # hopefully google isn't down! req = urllib.request.Request(URL) opener = urllib.request.build_opener(handler) try: opener.open(req, timeout=2).read(5) # open and read a few characters return True except urllib.error.URLError as err: return err except urllib.error.HTTPError as err: return err def getPacFiles(): """Return a list of possible auto proxy .pac files being used, based on the system registry (win32) or system preferences (OSX). """ pacFiles = [] if sys.platform == 'win32': try: import _winreg as winreg # used from python 2.0-2.6 except ImportError: import winreg # used from python 2.7 onwards net = winreg.OpenKey( winreg.HKEY_CURRENT_USER, "Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings") nSubs, nVals, lastMod = winreg.QueryInfoKey(net) subkeys = {} for i in range(nVals): thisName, thisVal, thisType = winreg.EnumValue(net, i) subkeys[thisName] = thisVal if ('AutoConfigURL' in list(subkeys.keys()) and len(subkeys['AutoConfigURL']) > 0): pacFiles.append(subkeys['AutoConfigURL']) elif sys.platform == 'darwin': import plistlib sysPrefs = plistlib.readPlist('/Library/Preferences/System' 'Configuration/preferences.plist') networks = sysPrefs['NetworkServices'] # loop through each possible network (e.g. Ethernet, Airport...) for network in list(networks.items()): netKey, network = network # the first part is a long identifier if 'ProxyAutoConfigURLString' in network['Proxies']: pacFiles.append(network['Proxies']['ProxyAutoConfigURLString']) return list(set(pacFiles)) # remove redundant ones def getWpadFiles(): """Return possible pac file locations from the standard set of .wpad locations NB this method only uses the DNS method to search, not DHCP queries, and so may not find all possible .pac locations. See http://en.wikipedia.org/wiki/Web_Proxy_Autodiscovery_Protocol """ # pacURLs.append("http://webproxy."+domain+"/wpad.dat") # for me finds a file that starts: function FindProxyForURL(url,host) # dynamcially chooses a proxy based on the requested url and host; how to # parse? domainParts = socket.gethostname().split('.') pacURLs = [] for ii in range(len(domainParts)): domain = '.'.join(domainParts[ii:]) pacURLs.append("http://wpad." + domain + "/wpad.dat") return list(set(pacURLs)) # remove redundant ones def proxyFromPacFiles(pacURLs=None, URL=None, log=True): """Attempts to locate and setup a valid proxy server from pac file URLs :Parameters: - pacURLs : list List of locations (URLs) to look for a pac file. This might come from :func:`~psychopy.web.getPacFiles` or :func:`~psychopy.web.getWpadFiles`. - URL : string The URL to use when testing the potential proxies within the files :Returns: - A urllib.request.ProxyHandler if successful (and this will have been added as an opener to the urllib) - False if no proxy was found in the files that allowed successful connection """ if pacURLs == None: # if given none try to find some pacURLs = getPacFiles() if pacURLs == []: # if still empty search for wpad files pacURLs = getWpadFiles() # for each file search for valid urls and test them as proxies for thisPacURL in pacURLs: if log: msg = 'proxyFromPacFiles is searching file:\n %s' logging.debug(msg % thisPacURL) try: response = urllib.request.urlopen(thisPacURL, timeout=2) except urllib.error.URLError: if log: logging.debug("Failed to find PAC URL '%s' " % thisPacURL) continue pacStr = response.read().decode('utf-8') # find the candidate PROXY strings (valid URLS), numeric and # non-numeric: pattern = r"PROXY\s([^\s;,:]+:[0-9]{1,5})[^0-9]" possProxies = re.findall(pattern, pacStr + '\n') for thisPoss in possProxies: proxUrl = 'http://' + thisPoss handler = urllib.request.ProxyHandler({'http': proxUrl}) if tryProxy(handler) == True: if log: logging.debug('successfully loaded: %s' % proxUrl) opener = urllib.request.build_opener(handler) urllib.request.install_opener(opener) return handler return False
[docs]def setupProxy(log=True): """Set up the urllib proxy if possible. The function will use the following methods in order to try and determine proxies: #. standard urllib.request.urlopen (which will use any statically-defined http-proxy settings) #. previous stored proxy address (in prefs) #. proxy.pac files if these have been added to system settings #. auto-detect proxy settings (WPAD technology) .. note: This can take time, as each failed attempt to set up a proxy involves trying to load a URL and timing out. Best to do in a separate thread. :Returns: True (success) or False (failure) """ global proxies # try doing nothing proxies = urllib.request.ProxyHandler(urllib.request.getproxies()) if tryProxy(proxies) is True: if log: logging.debug("Using standard urllib (static proxy or " "no proxy required)") # this will now be used globally for ALL urllib opening urllib.request.install_opener(urllib.request.build_opener(proxies)) return 1 # try doing what we did last time if len(prefs.connections['proxy']) > 0: proxConnPref = {'http': prefs.connections['proxy']} proxies = urllib.request.ProxyHandler(proxConnPref) if tryProxy(proxies) is True: if log: msg = 'Using %s (from prefs)' logging.debug(msg % prefs.connections['proxy']) # this will now be used globally for ALL urllib opening opener = urllib.request.build_opener(proxies) urllib.request.install_opener(opener) return 1 else: if log: logging.debug("Found a previous proxy but it didn't work") # try finding/using a proxy.pac file pacURLs = getPacFiles() if log: logging.debug("Found proxy PAC files: %s" % pacURLs) proxies = proxyFromPacFiles(pacURLs) # installs opener, if successful if (proxies and hasattr(proxies, 'proxies') and len(proxies.proxies['http']) > 0): # save that proxy for future prefs.connections['proxy'] = proxies.proxies['http'] prefs.saveUserPrefs() if log: msg = 'Using %s (from proxy PAC file)' logging.debug(msg % prefs.connections['proxy']) return 1 # try finding/using 'auto-detect proxy' pacURLs = getWpadFiles() proxies = proxyFromPacFiles(pacURLs) # installs opener, if successful if (proxies and hasattr(proxies, 'proxies') and len(proxies.proxies['http']) > 0): # save that proxy for future prefs.connections['proxy'] = proxies.proxies['http'] prefs.saveUserPrefs() if log: msg = 'Using %s (from proxy auto-detect)' logging.debug(msg % prefs.connections['proxy']) return 1 proxies = 0 return 0

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