Counts all possible single bit flip names for domain

bitflips.py

import re
import sys

# List of valid TLDs (this is a small subset, you may want to use a more comprehensive list)
VALID_TLDS = set(['com', 'org', 'net', 'edu', 'gov', 'io', 'co', 'uk', 'de', 'fr', 'jp', 'cn', 'au', 'us'])

def is_valid_domain(domain):
    pattern = r'^[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(\.[a-zA-Z]{2,})+$'
    if not re.match(pattern, domain):
        return False

    # Check if the TLD is valid
    tld = domain.split('.')[-1].lower()
    return tld in VALID_TLDS

def count_unique_valid_bit_flips(domain):
    valid_domains = set()
    domain_bytes = bytearray(domain.encode('ascii'))
    original_domain = domain.lower()
    original_length = len(original_domain)

    for i in range(len(domain_bytes)):
        for j in range(8):
            # Store the original byte
            original_byte = domain_bytes[i]

            # Flip the bit
            domain_bytes[i] ^= (1 << j)

            try:
                flipped_domain = domain_bytes.decode('ascii').lower()

                # Check if the length is the same and the domain is valid
                if (len(flipped_domain) == original_length and
                    flipped_domain != original_domain and
                    is_valid_domain(flipped_domain)):
                    valid_domains.add(flipped_domain)
                    print(flipped_domain)
            except UnicodeDecodeError:
                # If we can't decode, it's not a valid ASCII string
                pass

            # Restore the original byte
            domain_bytes[i] = original_byte

    return len(valid_domains)

if len(sys.argv) != 2:
    print("Usage: python script_name.py <domain>")
    print("Example: python script_name.py example.com")
    sys.exit(1)

domain = sys.argv[1]
result = count_unique_valid_bit_flips(domain)
print(f"Number of unique valid domain names with single bit flips for '{domain}': {result}")