Unshorten URLs, no matter how deep the rabbit hole goes.

longurl.py

import sys
import httplib
import urlparse

# maximum redirects to avoid loops; can't be arsed to build a graph
# and check for cycles.
maxredir = 10

# the orig variable is used to check if the last redirect results in the same
# URL. I've seen sites serving the actual real URL, but still give a 30x
# instead a 200.
def longurl(url, orig, count):
    p = urlparse.urlparse(url)
    h = httplib.HTTPConnection(p.netloc)
    h.request('HEAD', p.path)
    r = h.getresponse()
    if (r.status == 301 or r.status == 302) and r.getheader('Location') and url != orig and count != maxredir:
        count=count+1
        return longurl(r.getheader('Location'), url, count)
    else:
        return url

print longurl(sys.argv[1], "nil", 1)