import json
from dns import reversename, resolver, exception

misperrors = {'error': 'Error'}
mispattributes = {'input': ['ip-src', 'ip-dst', 'domain|ip'], 'output': ['hostname']}

# possible module-types: 'expansion', 'hover' or both
moduleinfo = {
    'version': '0.1',
    'author': 'Andreas Muehlemann',
    'description': 'Simple Reverse DNS expansion service to resolve reverse DNS from MISP attributes.',
    'module-type': ['expansion', 'hover'],
    'name': 'Reverse DNS',
    'logo': '',
    'requirements': ['DNS python library'],
    'features': 'The module takes an IP address as input and tries to find the hostname this IP address is resolved into.\n\nThe address of the DNS resolver to use is also configurable, but if no configuration is set, we use the Google public DNS address (8.8.8.8).\n\nPlease note that composite MISP attributes containing IP addresses are supported as well.',
    'references': [],
    'input': 'An IP address attribute.',
    'output': 'Hostname attribute the input is resolved into.',
}

# config fields that your code expects from the site admin
moduleconfig = ['nameserver']


def handler(q=False):
    if q is False:
        return False
    request = json.loads(q)
    if request.get('ip-dst'):
        toquery = request['ip-dst']
    elif request.get('ip-src'):
        toquery = request['ip-src']
    elif request.get('ip'):
        toquery = request['ip']
    elif request.get('domain|ip'):
        toquery = request['domain|ip'].split('|')[1]
    else:
        return False

    # reverse lookup for ip
    revname = reversename.from_address(toquery)
    r = resolver.Resolver()
    r.timeout = 2
    r.lifetime = 2
    if request.get('config'):
        if request['config'].get('nameserver'):
            nameservers = []
            nameservers.append(request['config'].get('nameserver'))
            r.nameservers = nameservers
    else:
        r.nameservers = ['8.8.8.8']

    try:
        answer = r.resolve(revname, 'PTR')
    except resolver.NXDOMAIN:
        misperrors['error'] = "NXDOMAIN"
        return misperrors
    except exception.Timeout:
        misperrors['error'] = "Timeout"
        return misperrors
    except Exception:
        misperrors['error'] = "DNS resolving error"
        return misperrors

    r = {'results': [{'types': mispattributes['output'],'values':[str(answer[0])]}]}
    return r


def introspection():
    return mispattributes


def version():
    moduleinfo['config'] = moduleconfig
    return moduleinfo