http - Proxy Check in python

Question

I have written a script in python that uses cookies and POST/GET. I also included proxy support in my script. However, when one enters a dead proxy, the script crashes. Is there any way to check if a proxy is dead/alive before running the rest of my script?

Furthermore, I noticed that some proxies don't handle cookies/POST headers properly. Is there any way to fix this?

Answer 1

The simplest was is to simply catch the IOError exception from urllib:

try:
    urllib.urlopen(
        "http://example.com",
        proxies={'http':'http://example.com:8080'}
    )
except IOError:
    print "Connection error! (Check proxy)"
else:
    print "All was fine"

Also, from this blog post - "check status proxy address" (with some slight improvements):

for python 2

import urllib2
import socket

def is_bad_proxy(pip):    
    try:
        proxy_handler = urllib2.ProxyHandler({'http': pip})
        opener = urllib2.build_opener(proxy_handler)
        opener.addheaders = [('User-agent', 'Mozilla/5.0')]
        urllib2.install_opener(opener)
        req=urllib2.Request('http://www.example.com')  # change the URL to test here
        sock=urllib2.urlopen(req)
    except urllib2.HTTPError, e:
        print 'Error code: ', e.code
        return e.code
    except Exception, detail:
        print "ERROR:", detail
        return True
    return False

def main():
    socket.setdefaulttimeout(120)

    # two sample proxy IPs
    proxyList = ['125.76.226.9:80', '213.55.87.162:6588']

    for currentProxy in proxyList:
        if is_bad_proxy(currentProxy):
            print "Bad Proxy %s" % (currentProxy)
        else:
            print "%s is working" % (currentProxy)

if __name__ == '__main__':
    main()

for python 3

import urllib.request
import socket
import urllib.error

def is_bad_proxy(pip):    
    try:
        proxy_handler = urllib.request.ProxyHandler({'http': pip})
        opener = urllib.request.build_opener(proxy_handler)
        opener.addheaders = [('User-agent', 'Mozilla/5.0')]
        urllib.request.install_opener(opener)
        req=urllib.request.Request('http://www.example.com')  # change the URL to test here
        sock=urllib.request.urlopen(req)
    except urllib.error.HTTPError as e:
        print('Error code: ', e.code)
        return e.code
    except Exception as detail:
        print("ERROR:", detail)
        return True
    return False

def main():
    socket.setdefaulttimeout(120)

    # two sample proxy IPs
    proxyList = ['125.76.226.9:80', '25.176.126.9:80']

    for currentProxy in proxyList:
        if is_bad_proxy(currentProxy):
            print("Bad Proxy %s" % (currentProxy))
        else:
            print("%s is working" % (currentProxy))

if __name__ == '__main__':
    main() 

Remember this could double the time the script takes, if the proxy is down (as you will have to wait for two connection-timeouts).. Unless you specifically have to know the proxy is at fault, handling the IOError is far cleaner, simpler and quicker..