"""
-------------------------------------
# @Time    : 2021/1/11 17:41
# @Author  : ls
# @File    : dns_client.py
# @IDE: PyCharm
--------------------------------------
"""
import socket
import time
from utils.read_config import ConfigRead
from utils.package_tools import PackageTools


class DNSClient:
    def __init__(self):
        conf = ConfigRead()
        self.REMOTE_DNS_SERVER_ADDRESS = conf.read_option_value('SERVER_CONFIG', 'REMOTE_DNS_SERVER_ADDRESS')
        self.REMOTE_DNS_SERVER_PORT = int(conf.read_option_value('SERVER_CONFIG', 'REMOTE_DNS_SERVER_PORT'))
        self.RESPONSE_TIMEOUT = 3
        self.BUFFERSIZE = 1024

    def query_dns_from_remote_dns_server(self, pkg):
        """
        从公网DNS服务器获取解析信息
        :param pkg:客户端传入的DNS请求报文
        :return:公网DNS服务器响应报文
        """
        pt = PackageTools()
        pt.package = pkg
        domain_name = pt.domain_name()
        client = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        client.settimeout(self.RESPONSE_TIMEOUT)
        client.sendto(pkg, (self.REMOTE_DNS_SERVER_ADDRESS, self.REMOTE_DNS_SERVER_PORT))
        while True:
            time.sleep(0.001)
            try:
                server_response_data, server_info = client.recvfrom(self.BUFFERSIZE)
                return [True, server_response_data]
            except socket.timeout:
                return [False, 'DNS server response timeout[{}]'.format(domain_name)]
            except ConnectionError:
                return [False, '[WinError 10054] 远程主机强迫关闭了一个现有的连接。[{}]'
                               .format(domain_name)]