<filename>dnsmock/lib.py
# Copyright (c) 2021 <NAME>

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"""Resolver Module"""

import socket
from functools import wraps


# mock /etc/hosts
# lock it in multithreading or use multiprocessing if an endpoint
# is bound to multiple IPs frequently
etc_hosts = {}


def custom_resolver(builtin_resolver):
    """
    Custom resolver
    """

    @wraps(builtin_resolver)
    def wrapper(*args, **kwargs):
        try:
            return etc_hosts[args[:2]]
        except KeyError:
            # fall back to builtin_resolver for endpoints not in etc_hosts
            return builtin_resolver(*args, **kwargs)

    return wrapper


def bind_ip(domain_name, port, ip_address):
    '''
    resolve (domain_name,port) to a given ip
    '''
    key = (domain_name, port)
    # (family, type, proto, canonname, sockaddr)

    value = (socket.AF_INET,
             socket.SOCK_STREAM, 6, '', (ip_address, port))
    etc_hosts[key] = [value]


# monkey patching
socket.getaddrinfo = custom_resolver(socket.getaddrinfo)
