debug-tools/tools.py

import random
import dns.resolver
import subprocess
import tempfile
import binascii
from cryptography import x509
from cryptography.hazmat.backends import default_backend
import datetime
from dns import resolver, dnssec, name, exception
import time

resolver = dns.resolver.Resolver()
resolver.nameservers = ["194.50.5.28","194.50.5.27","194.50.5.26"]
resolver.port = 53


def check_ssl(domain: str):    
    domain_check = False
    returns = {"success": False,"valid":False}
    try:
        # Query the DNS record
        response = resolver.resolve(domain, "A")
        records = []
        for record in response:
            records.append(str(record))

        if not records:
            return {"success": False, "message": "No A record found for " + domain}
            
        returns["ip"] = records[0]
        if len(records) > 1:
            returns["other_ips"] = records[1:]

        returns["dnssec"] = validate_dnssec(domain)


        # Get the first A record        
        ip = records[0]
        
        # Run the openssl s_client command
        s_client_command = ["openssl","s_client","-showcerts","-connect",f"{ip}:443","-servername",domain,]

        s_client_process = subprocess.Popen(s_client_command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE)
        s_client_output, _ = s_client_process.communicate(input=b"\n")
        
        certificates = []
        current_cert = ""
        for line in s_client_output.split(b"\n"):
            current_cert += line.decode("utf-8") + "\n"
            if "-----END CERTIFICATE-----" in line.decode("utf-8"):
                certificates.append(current_cert)
                current_cert = ""

        # Remove anything before -----BEGIN CERTIFICATE-----
        certificates = [cert[cert.find("-----BEGIN CERTIFICATE-----"):] for cert in certificates]

        if not certificates:
            returns["cert"] = {
                "cert":"",
                "domains": [],
                "domain": False,
                "expired": False,
                "valid": False,
                "expiry_date": ""
                }
            returns["tlsa"] = {
                "server": "",
                "nameserver": "",
                "match": False
                }
            
        else:
            
            cert = certificates[0]
            returns["cert"] = {"cert": cert}
        
            with tempfile.NamedTemporaryFile(mode="w", delete=False) as temp_cert_file:
                temp_cert_file.write(cert)
                temp_cert_file.seek(0)

            tlsa_command = ["openssl","x509","-in",temp_cert_file.name,"-pubkey","-noout","|","openssl","pkey","-pubin","-outform","der","|","openssl","dgst","-sha256","-binary",]
        
            tlsa_process = subprocess.Popen(" ".join(tlsa_command), shell=True, stdout=subprocess.PIPE)
            tlsa_output, _ = tlsa_process.communicate()

            tlsa_server = "3 1 1 " + binascii.hexlify(tlsa_output).decode("utf-8")

        
            returns["tlsa"] = {
                "server": tlsa_server,
                "nameserver": "",
                "match": False
                }


            # Get domains
            cert_obj = x509.load_pem_x509_certificate(cert.encode("utf-8"), default_backend())

            domains = []
            for ext in cert_obj.extensions:
                if ext.oid == x509.ExtensionOID.SUBJECT_ALTERNATIVE_NAME:
                    san_list = ext.value.get_values_for_type(x509.DNSName)
                    domains.extend(san_list)
        
            # Extract the common name (CN) from the subject
            common_name = cert_obj.subject.get_attributes_for_oid(x509.NameOID.COMMON_NAME)
            if common_name:
                if common_name[0].value not in domains:
                    domains.append(common_name[0].value)


            if domains:
                cert_domains = []
                for cn in domains:
                    cert_domains.append(cn)
                    if cn == domain:
                        domain_check = True
                    elif cn.startswith("*."):
                        if domain.endswith(cn[1:]):
                            domain_check = True

            returns["cert"]["domains"] = cert_domains
            returns["cert"]["domain"] = domain_check

            expiry_date = cert_obj.not_valid_after_utc
            # Check if expiry date is past
            if expiry_date < datetime.datetime.now(datetime.timezone.utc):
                returns["cert"]["expired"] = True
                returns["cert"]["valid"] = False
                
            else:
                returns["cert"]["expired"] = False
                returns["cert"]["valid"] = True if domain_check else False

            returns["cert"]["expiry_date"] = expiry_date.strftime("%d %B %Y %H:%M:%S")

        try:
            # Check for TLSA record
            response = resolver.resolve("_443._tcp."+domain, "TLSA")
            tlsa_records = []
            for record in response:
                tlsa_records.append(str(record))

            if tlsa_records:
                returns["tlsa"]["nameserver"] = tlsa_records[0]
                if tlsa_server == tlsa_records[0]:
                    returns["tlsa"]["match"] = True
        except:
            returns["tlsa"]["error"] = "No TLSA record found on DNS"

        # Check if valid
        if returns["cert"]["valid"] and returns["tlsa"]["match"] and returns["dnssec"]["valid"]:
            returns["valid"] = True
        
        returns["success"] = True
        return returns
            
    # Catch all exceptions
    except Exception as e:
        returns["message"] = f"An error occurred: {e}"
        return returns
    

def validate_dnssec(domain):
    # Pick a random resolver
    resolverIP = random.choice(resolver.nameservers)
    # delv @194.50.5.28 -a hsd-ksk nathan.woodburn A +rtrace +vtrace
    command = f"delv @{resolverIP} -a hsd-ksk {domain} A +rtrace +vtrace"
    result = subprocess.run(command, shell=True, capture_output=True, text=True)
    if "; fully validated" in result.stdout:
        return {"valid": True, "message": "DNSSEC is valid", "output": result.stderr + result.stdout}
    else:
        return {"valid": False, "message": "DNSSEC is not valid", "output": result.stderr + result.stdout}