DMARC_and_SPF_Check.py

import dns.resolver
import sys
from tld import get_fld

def get_root_domain(domain):
    return get_fld(domain, fix_protocol=True)

def check_dmarc(domain):
    try:
        answers = dns.resolver.resolve(f'_dmarc.{domain}', 'TXT')
        for rdata in answers:
            if 'DMARC1' in str(rdata):
                return str(rdata)
        return None
    except dns.resolver.NXDOMAIN:
        return None
    except Exception as e:
        return None

def check_spf(domain):
    try:
        answers = dns.resolver.resolve(f'{domain}', 'TXT')
        for rdata in answers:
            if 'v=spf1' in str(rdata).lower():
                spf_record = str(rdata)
                if "+all" in spf_record or "?all" in spf_record:
                    return spf_record
        return None
    except dns.resolver.NXDOMAIN:
        return None
    except Exception as e:
        return None

def analyze_dmarc(original_domain, root_domain, dmarc_record, spf_record):
    # Consistently formatting the domain to be 40 characters wide
    domain_width = 40
    #print(f"{original_domain:<{domain_width}}", end="")

    if dmarc_record is None:
        print(f"{original_domain:<{domain_width}}No DMARC record found")
    else:
        record_parts = dmarc_record.split(';')
        for part in record_parts:
            part = part.strip().lower()
            if part.startswith('p=none') or part.startswith('sp=none'):
                print(f"{original_domain:<{domain_width}}DMARC policy is 'none' (p=none or sp=none)")
                return
            if part.startswith('pct='):
                try:
                    pct = int(part.split('=')[1])
                    if pct < 100:
                        print(f"{original_domain:<{domain_width}}DMARC percentage is less than 100% (pct={pct})")
                        return
                except ValueError:
                    pass

    if spf_record is not None:
        print(f"{original_domain:<{domain_width}}SPF record contains '+all' or '?all': {spf_record}")

def main(input_file):
    with open(input_file, 'r') as file:
        for line in file:
            original_domain = line.strip()
            if original_domain:
                root_domain = get_root_domain(original_domain)
                dmarc_record = check_dmarc(root_domain)
                spf_record = check_spf(root_domain)
                analyze_dmarc(original_domain, root_domain, dmarc_record, spf_record)

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python script.py <input_file>")
        sys.exit(1)
    
    input_file = sys.argv[1]
    main(input_file)