pyafraid.py

#!/usr/bin/env python
""" This script updates the the afraid.org DDNS server to point to the
    the new current public IP address.
"""
import urllib2
import optparse
import sys

try:
    from hashlib import sha1
except ImportError: # python < 2.5
    from sha import new as sha1

__version__ = '0.1'

API_URL = "http://freedns.afraid.org/api/?action=getdyndns&sha="

def error(msg, code=1):
    print >> sys.stderr, "%s: error: %s" % (sys.argv[0], msg)
    sys.exit(code)

def validate_args(parser, options, args):
    if len(args) != 1:
        parser.error("Incorrect number of arguments. Maybe you omitted update/query?")

    action= args[0]

    # we will only require username and password if the SHA-1 hash is not given

    if action.lower() == "update":
        if options.sha_hash:
            required_options = ['hostname']
        else:
            required_options = ['username', 'password', 'hostname']
    elif action.lower() == "query":
        if options.sha_hash:
            required_options = []
        else:
            required_options = ['username', 'password']
    else:
        parser.error("Either 'update' or 'query' must be provided.")

    for required_opt in required_options:
        if not getattr(options, required_opt, None):
            parser.error("The --%s option must be provided." % required_opt)

def parse_args():
    parser = optparse.OptionParser(usage="%prog update|query [-h] [-u <username> -p <password>]|[-s <sha_hash>] [-n <hostname>]")
    parser.add_option('-u', '--username', help="The freedns.afraid.org username",
                      dest="username", default=None)
    parser.add_option('-p', '--password', help="The associated password",
                      dest='password', default=None)
    parser.add_option('-n', '--hostname', help="The name of the host to update or query",
                       dest='hostname', default=None)
    parser.add_option('-s', '--sha-hash', help="The SHA-1 hash from the API interface URL. Don't use this with the -u and -p options.",
                      dest="sha_hash", default=None)

    options, args = parser.parse_args()
    validate_args(parser, options, args)

    return options, args[0]

def get_sha(username, password):
    to_hash = "|".join([username, password])
    return sha1(to_hash).hexdigest()

def parse_ascii_api(s):
    keys = ('desc', 'ip', 'url')
    records = []
    for record_str in s.splitlines():
        if record_str.strip():
            records.append(dict(zip(keys, record_str.split('|'))))

    return records

def get_records(sha_hash):
    url = API_URL + sha_hash
    f = urllib2.urlopen(url)
    #TODO: handle invalid hash
    result = f.read()
    records = parse_ascii_api(result)
    return records

# TODO: handle errors
def update_url(record):
    print "Attempting to update %s..." % record['desc']
    f = urllib2.urlopen(record['url'])
    result = f.read()
    print "response from server:\n %s" % result

# TODO: this should really be a method of some Records class...
def get_record_by_desc(records, desc):
    for record in records:
        if record['desc'] == desc:
            return record

    error("No record with description '%s'" % desc)

def perform_update(opts):
    if not opts.sha_hash:
        sha_hash = get_sha(opts.username, opts.password)
    else:
        sha_hash = opts.sha_hash
    records = get_records(sha_hash)
    record = get_record_by_desc(records, opts.hostname)
    update_url(record)

def print_record(record):
    for key, value in record.iteritems():
        print "%s:\t%s" % (key, value)

    print "\n",

def print_results(records):
    if not isinstance(records, list):
        records = [records]

    print "\n",
    for record in records:
        print_record(record)


def perform_query(opts):
    if not opts.sha_hash:
        sha_hash = get_sha(opts.username, opts.password)
    else:
        sha_hash = opts.sha_hash
    result = get_records(sha_hash)
    if opts.hostname:
        result = get_record_by_desc(result, opts.hostname)

    print_results(result)

def perform_action(action, opts):
    if action == "query":
        perform_query(opts)
    elif action == "update":
        perform_update(opts)

def main():
    opts, action = parse_args()
    perform_action(action, opts)

if __name__ == "__main__":
    main()