doi_lookup.py

#!/usr/bin/python

import httplib
import sys

base_url = "dx.doi.org"
for line in sys.stdin:
    doi = line.strip()	
    url = base_url + doi
    conn = httplib.HTTPConnection(base_url)
    conn.request("HEAD", "/" + doi)
    res = conn.getresponse()
    e = 1 if res.status == 303 else 0
    print doi + "\t" + str(e)

for caching metadata instead of calling the resolver, we can use the works endpoint of the API, something like:

base_url = "http://api.crossref.org/works/"
for line in sys.stdin:
    url = base_url + doi
    try:
        request = urllib.request.Request(url)
        response = urllib.request.urlopen(request)
        r = response.read().decode('utf-8')
        response.close()
        j = json.loads(r)
        dlist[doi] =j['message']
    except:
        dlist[doi] = None