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part_1.py
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part_1.py
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from dataclasses import dataclass
import dataclasses
import struct
@dataclass
class DNSHeader:
id: int
flags: int
num_questions: int = 0
num_answers: int = 0
num_authorities: int = 0
num_additionals: int = 0
@dataclass
class DNSQuestion:
name: bytes
type_: int
class_: int
def header_to_bytes(header):
fields = dataclasses.astuple(header)
return struct.pack('!HHHHHH', *fields)
def question_to_bytes(question):
return question.name + struct.pack('!HH', question.type_, question.class_)
def encode_dns_name(domain_name):
encoded = b''
for part in domain_name.encode('ascii').split(b'.'):
encoded += bytes([len(part)]) + part
return encoded + b'\x00'
import random
TYPE_A = 1
CLASS_IN = 1
def build_query(domain_name, record_type):
name = encode_dns_name(domain_name)
id = random.randint(0, 65535)
RECURSION_DESIRED = 1 << 8
header = DNSHeader(id=id, num_questions=1, flags=RECURSION_DESIRED)
question = DNSQuestion(name=name, type_=record_type, class_=CLASS_IN)
return header_to_bytes(header) + question_to_bytes(question)
import socket