Simple unit convertor in python

This function uses the google calculator api
http://www.google.com/ig/calculator?hl=en&q=1EUR%3D%3FUSD

import urllib, urllib2
import socket

# Crawl header #
default_header = { 'User-Agent' :
    'Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.5) Gecko/2008121622 Ubuntu/8.10 (intrepid) Firefox/3.0.5;'}

def getpage(pageurl, pageargs = None, pageheaderargs = {}):
  fail = 0
  content = reply_header = None
  pageheaders = default_header
  pageheaders.update(pageheaderargs)
  while True:
    print pageurl
    retry = 0
    try:
      params = urllib.urlencode(pageargs) if pageargs else None
      req = urllib2.Request(pageurl, params, pageheaders)
      page = urllib2.urlopen(req)
      content = page.read()
      reply_header = str(page.headers).split('\r\n')
      page.close()
    except urllib2.HTTPError, e:
      retry = 1
    except IOError, e:
      retry = 1
    except socket.timeout, e:
      retry = 1
    except socket.sslerror, e:
      retry = 1
    if retry:
      fail += 1
      if fail == 5:
        print 'Failed to retrieve' + pageurl + ': ' + str(e)
        return (reply_header, content)
      else:
        continue
    break
  return (reply_header, content)

def convert(unit1, unit2):
  query = '1%s=?%s' % (unit1, unit2)
  (header, content) = getpage('http://www.google.com/ig/calculator?hl=en&q=' + query)
  reresult = re.search('rhs: \"(.*?) ', content)
  result = reresult.expand(r'\1') if reresult else 'Error'
  return result if result != '' else 'Error'