#!/usr/bin/env python3
import argparse
import socket
import ssl
from cryptography import x509

parser = argparse.ArgumentParser(description='Show ssl certificate info')
parser.add_argument(type=str,
                    dest='host',
                    help='Address on which ssl cert is served.')
parser.add_argument('-H',
                    '--hostname',
                    type=str,
                    required=False,
                    default=None,
                    dest='hostname',
                    help='Hostname to be used in ssl context.')

args = parser.parse_args()

address: list[str] = args.host.split(':')
HOST: str = address[0]
HOSTNAME: str
if args.hostname:
    HOSTNAME = args.hostname
else:
    HOSTNAME = HOST

PORT: int
if len(address) > 1:
    PORT = int(address[1])
else:
    PORT = 443

context: ssl.SSLContext = ssl.create_default_context()
context.check_hostname = False
context.verify_mode = ssl.CERT_NONE

conn: ssl.SSLSocket
with context.wrap_socket(socket.socket(socket.AF_INET),
                         server_hostname=HOSTNAME,
                         do_handshake_on_connect=True) as conn:

    conn.settimeout(5.0)
    conn.connect((HOST, PORT))
    cert_pem = ssl.DER_cert_to_PEM_cert(conn.getpeercert(binary_form=True))
    cert: x509.Certificate = x509.load_pem_x509_certificate(cert_pem.encode())

    key: x509.Extension
    san = ""
    for key in cert.extensions:
        if key.oid._name == 'subjectAltName':
            san = f"subjectAltName: {key.value}"

    print(f"""
Issuer: {cert.issuer}
Subject: {cert.subject}
{san}
Not valid before: {cert.not_valid_before}
Not valid after: {cert.not_valid_after}
Public key type: {cert.public_key().__class__.__name__}
Public key size: {cert.public_key().key_size}
Version: {cert.version}
Serial number: {cert.serial_number}
Signature algorithm: {cert.signature_algorithm_oid._name}
Signature hash: {cert.signature_hash_algorithm.name}
""")

    key: x509.Extension
    for key in cert.extensions:
        print(f'{key.oid._name}: {key.value}')

    print(f"""
SSL connection context info:
    SSL/TLS version: {conn.version()}
    Ciphers: {conn.cipher()}
    Hostname: {conn.server_hostname}
""")

    print(f"""PEM cert:
    {cert_pem}
    """)