check_crt.py

#!/bin/env python3
import sys
import os
import time
import datetime
from sh import openssl
from datetime import datetime as dt


if len(sys.argv) < 2:
    print("Usage: ", sys.argv[0], " <domain>")
    sys.exit(1)

domain = sys.argv[1]

if not domain:
    print("Usage: ", sys.argv[0], " <domain>")
    sys.exit(1)

cert = ""
found_cert = False

for line in openssl.s_client(*"-connect {0}:443 -servername {0}".format(domain).split(" "), _in=os.devnull):
    if "-----END CERTIFICATE-----" in line:
        cert += line
        break
    elif "-----BEGIN CERTIFICATE-----" in line:
        found_cert = True
        cert += line
    elif found_cert == True:
        cert += line

if found_cert == False or cert.strip() == "":
    print(0)
    sys.exit(0)


end_date = openssl.x509(*"-noout -enddate".split(" "), _in=cert).strip().split("=")[1]
# Mar 20 20:44:00 2016 GMT
delta = dt.strptime(end_date, "%b %d %H:%M:%S %Y %Z") - dt.utcnow()

print(delta.days)