DNS服务器。蟒蛇。如果域名在黑名单中，如何将用户重定向到特定的IP地址

Question

我找到了如何在YouTube上创建自己的dns服务器的指南。但是我需要您的帮助来创建IP地址黑名单，因此，如果有人想访问被禁的IP地址，他们将重定向到特定的IP地址，例如localhost。

在代码下方，并在指南视频上链接。

import socket, glob, json

port = 53
ip = '127.0.0.1'

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind((ip, port))

def load_zones():

    jsonzone = {}
    zonefiles = glob.glob('zones/*.zone')

    for zone in zonefiles:
        with open(zone) as zonedata:
            data = json.load(zonedata)
            zonename = data["$origin"]
            jsonzone[zonename] = data
    return jsonzone

zonedata = load_zones()

def getflags(flags):

    byte1 = bytes(flags[:1])
    byte2 = bytes(flags[1:2])

    rflags = ''

    QR = '1'

    OPCODE = ''
    for bit in range(1,5):
        OPCODE += str(ord(byte1)&(1<<bit))

    AA = '1'

    TC = '0'

    RD = '0'

    # Byte 2

    RA = '0'

    Z = '000'

    RCODE = '0000'

    return int(QR+OPCODE+AA+TC+RD, 2).to_bytes(1, byteorder='big')+int(RA+Z+RCODE, 2).to_bytes(1, byteorder='big')

def getquestiondomain(data):

    state = 0
    expectedlength = 0
    domainstring = ''
    domainparts = []
    x = 0
    y = 0
    for byte in data:
        if state == 1:
            if byte != 0:
                domainstring += chr(byte)
            x += 1
            if x == expectedlength:
                domainparts.append(domainstring)
                domainstring = ''
                state = 0
                x = 0
            if byte == 0:
                domainparts.append(domainstring)
                break
        else:
            state = 1
            expectedlength = byte
        y += 1

    questiontype = data[y:y+2]

    return (domainparts, questiontype)

def getzone(domain):
    global zonedata

    zone_name = '.'.join(domain)
    return zonedata[zone_name]

def getrecs(data):
    domain, questiontype = getquestiondomain(data)
    qt = ''
    if questiontype == b'\x00\x01':
        qt = 'a'

    zone = getzone(domain)

    return (zone[qt], qt, domain)

def buildquestion(domainname, rectype):
    qbytes = b''

    for part in domainname:
        length = len(part)
        qbytes += bytes([length])

        for char in part:
            qbytes += ord(char).to_bytes(1, byteorder='big')

    if rectype == 'a':
        qbytes += (1).to_bytes(2, byteorder='big')

    qbytes += (1).to_bytes(2, byteorder='big')

    return qbytes

def rectobytes(domainname, rectype, recttl, recval):

    rbytes = b'\xc0\x0c'

    if rectype == 'a':
        rbytes = rbytes + bytes([0]) + bytes([1])

    rbytes = rbytes + bytes([0]) + bytes([1])

    rbytes += int(recttl).to_bytes(4, byteorder='big')

    if rectype == 'a':
        rbytes = rbytes + bytes([0]) + bytes([4])

        for part in recval.split('.'):
            rbytes += bytes([int(part)])
    return rbytes

def buildresponse(data):

    # Transaction ID
    TransactionID = data[:2]

    # Get the flags
    Flags = getflags(data[2:4])

    # Question Count
    QDCOUNT = b'\x00\x01'

    # Answer Count
    ANCOUNT = len(getrecs(data[12:])[0]).to_bytes(2, byteorder='big')

    # Nameserver Count
    NSCOUNT = (0).to_bytes(2, byteorder='big')

    # Additonal Count
    ARCOUNT = (0).to_bytes(2, byteorder='big')

    dnsheader = TransactionID+Flags+QDCOUNT+ANCOUNT+NSCOUNT+ARCOUNT

    # Create DNS body
    dnsbody = b''

    # Get answer for query
    records, rectype, domainname = getrecs(data[12:])

    dnsquestion = buildquestion(domainname, rectype)

    for record in records:
        dnsbody += rectobytes(domainname, rectype, record["ttl"], record["value"])

    return dnsheader + dnsquestion + dnsbody


while 1:
    data, addr = sock.recvfrom(512)
    r = buildresponse(data)
    sock.sendto(r, addr)

{
    "$origin": "howcode.org.",
    "$ttl": 3600,
    "soa": {
        "mname": "ns1.howcode.org.",
        "rname": "admin.howcode.org.",
        "serial": "{time}",
        "refresh": 3600,
        "retry": 600,
        "expire": 604800,
        "minimum": 86400
    },
    "ns": [
        { "host": "ns1.howcode.org." },
        { "host": "ns2.howcode.org." }
    ],
    "a": [
        { "name": "@", "ttl": 400, "value": "255.255.255.255" },
        { "name": "@", "ttl": 400, "value": "127.0.0.1" },
        { "name": "@", "ttl": 400, "value": "127.0.0.1" },
        { "name": "@", "ttl": 400, "value": "127.0.0.1" },
        { "name": "@", "ttl": 400, "value": "10.10.10.10" }
    ]
}

https://www.youtube.com/watch?v=wuo_nWN4YJU&list=PLBOh8f9FoHHhvO5e5HF_6mYvtZegobYX2&index=9