DNS Utilities

class InterceptResolver(BaseResolver):
    """
    Intercepting resolver that matches queries against patterns and handles
    them locally or forwards to upstream server.
    
    Args:
        address (str): Upstream DNS server address
        port (int, optional): Upstream DNS server port (default: 53)
        ttl (int, optional): TTL for intercepted responses (default: 60)
        intercept (list, optional): List of domains/patterns to intercept
        skip (list, optional): List of domains/patterns to skip interception
        nxdomain (list, optional): List of domains to return NXDOMAIN
        forward (list, optional): List of domains to always forward
        all_qtypes (bool, optional): Intercept all query types (default: False)
        timeout (int, optional): Upstream timeout in seconds (default: 5)
    """
    def __init__(self, address, port, ttl, intercept, skip, nxdomain, forward, all_qtypes, timeout=0): ...
    
    def resolve(self, request, handler):
        """
        Resolve query with interception logic.
        
        Args:
            request (DNSRecord): DNS query to resolve
            handler (DNSHandler): Request handler instance
            
        Returns:
            DNSRecord: DNS response (intercepted or proxied)
        """

class PassthroughDNSHandler(DNSHandler):
    """
    DNS handler that forwards requests directly to upstream server
    without parsing DNS packets for improved performance.
    """
    def get_reply(self, data):
        """
        Forward raw DNS packet to upstream server.
        
        Args:
            data (bytes): Raw DNS query packet
            
        Returns:
            bytes: Raw DNS response packet from upstream
        """

def send_tcp(data, host, port):
    """
    Send DNS query over TCP and return response.
    
    Args:
        data (bytes): DNS query packet
        host (str): Target server address
        port (int): Target server port
        
    Returns:
        bytes: DNS response packet
    """

def send_udp(data, host, port):
    """
    Send DNS query over UDP and return response.
    
    Args:
        data (bytes): DNS query packet
        host (str): Target server address
        port (int): Target server port
        
    Returns:
        bytes: DNS response packet
    """

class DigParser:
    """
    Parser for DiG (Domain Information Groper) output format.
    Enables parsing of DiG command output for DNS record extraction.
    """
    def __init__(self): ...
    
    def parse(self, dig_output):
        """
        Parse DiG output and extract DNS records.
        
        Args:
            dig_output (str): DiG command output
            
        Returns:
            DNSRecord: Parsed DNS record from DiG output
        """
        
    def parse_response(self, response_text):
        """
        Parse DiG response section.
        
        Args:
            response_text (str): DiG response section text
            
        Returns:
            list[RR]: List of parsed resource records
        """

class DNSError(Exception):
    """Base exception class for DNS-related errors."""
    
class DNSLabelError(Exception):
    """Exception for DNS label processing errors."""
    
class BufferError(Exception):
    """Exception for buffer operation errors."""
    
class BimapError(Exception):
    """Exception for bidirectional mapping errors."""

from dnslib import *
from dnslib.server import DNSServer
from dnslib.intercept import InterceptResolver

# Create intercepting resolver
resolver = InterceptResolver(
    address="8.8.8.8",
    port=53,
    ttl=300,
    intercept=["example.com", "*.local"],
    nxdomain=["blocked.com"],
    forward=["important.com"],
    all_qtypes=True,
    timeout=5
)

# Start DNS server with intercepting resolver
server = DNSServer(resolver, port=5353, address="127.0.0.1")
server.start_thread()

print("Intercepting DNS server running on 127.0.0.1:5353")

from dnslib import *
from dnslib.proxy import send_tcp, send_udp

# Create DNS query
query = DNSRecord.question("example.com", "A")
query_data = query.pack()

# Send via UDP
try:
    response_data = send_udp(query_data, "8.8.8.8", 53)
    response = DNSRecord.parse(response_data)
    print(f"UDP Response: {response.a}")
except Exception as e:
    print(f"UDP query failed: {e}")

# Send via TCP for large responses
try:
    response_data = send_tcp(query_data, "8.8.8.8", 53)
    response = DNSRecord.parse(response_data)
    print(f"TCP Response: {response.a}")
except Exception as e:
    print(f"TCP query failed: {e}")

from dnslib import *
from dnslib.server import DNSServer
from dnslib.proxy import ProxyResolver, PassthroughDNSHandler

# Create proxy resolver
resolver = ProxyResolver("8.8.8.8", 53, timeout=5)

# Use passthrough handler for maximum performance
server = DNSServer(
    resolver=resolver,
    port=5353,
    address="127.0.0.1",
    handler=PassthroughDNSHandler
)

server.start_thread()
print("High-performance proxy server running on 127.0.0.1:5353")

from dnslib.digparser import DigParser
import subprocess

# Run DiG command and capture output
dig_cmd = ["dig", "@8.8.8.8", "example.com", "A"]
result = subprocess.run(dig_cmd, capture_output=True, text=True)

# Parse DiG output
parser = DigParser()
try:
    dns_record = parser.parse(result.stdout)
    print(f"Parsed from DiG: {dns_record}")
    
    # Extract answer records
    for rr in dns_record.rr:
        print(f"Answer: {rr}")
except Exception as e:
    print(f"Failed to parse DiG output: {e}")

from dnslib import *
from dnslib.label import DNSLabelError

try:
    # Try to create DNS record with invalid data
    query = DNSRecord.question("invalid..domain", "A")
    response_data = query.send("8.8.8.8", 53)
    response = DNSRecord.parse(response_data)
    
except DNSError as e:
    print(f"DNS error: {e}")
except DNSLabelError as e:
    print(f"DNS label error: {e}")
except BufferError as e:
    print(f"Buffer error: {e}")
except Exception as e:
    print(f"Unexpected error: {e}")