#!/usr/bin/python3.8
# coding=utf-8

import OpenSSL
import ssl
import sys
import datetime

def getCertificateWithSNI(strHost:str, port=443 ):
        conn = ssl.create_connection((strHost, port))
        context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
        sock = context.wrap_socket(conn, server_hostname=strHost)
        return ssl.DER_cert_to_PEM_cert(sock.getpeercert(True))

def main():
        if not 2 == len(sys.argv):
                print('invalid arguments count - hostname required')
                return 1
        strHost = sys.argv[1].strip()
        cert = getCertificateWithSNI(strHost)
        x509 = OpenSSL.crypto.load_certificate(OpenSSL.crypto.FILETYPE_PEM, cert)
        strExp = x509.get_notAfter().decode("utf-8")[:14]
        dExp = datetime.datetime.strptime(strExp, '%Y%m%d%H%M%S')
        strDays = str((dExp - datetime.datetime.now()).days)
        status_file = open("/tmp/sslexp_"+strHost, "w", encoding='utf8')
        status_file.write(strDays)
        status_file.close()
        return 0

if __name__ == "__main__":
        sys.exit(main())