Не може да получи партньорски сертификат в клиент на Python, използвайки ssl.SSSLContext() на OpenSSL

Бих искал да наблегна на [Python 3.Docs] : SSLSocket.getpeercert(binary_form=False), който съдържа много информация (която пропуснах последния път(и)).
Също така разбрах за ssl._ssl._test_decode_cert, като разгледах имплементацията на SSLSocket.getpeercert ("${PYTHON_SRC_DIR}/Modules/_ssl.c").

code00.py:

#!/usr/bin/env python3

import sys
import os
import socket
import ssl
import itertools


def _get_tmp_cert_file_name(host, port):
    return os.path.join(os.path.dirname(os.path.abspath(__file__)), "_".join(("cert", host, str(port), str(os.getpid()), ".crt")))


def _decode_cert(cert_pem, tmp_cert_file_name):
    #print(tmp_cert_file_name)
    with open(tmp_cert_file_name, "w") as fout:
        fout.write(cert_pem)
    try:
        return ssl._ssl._test_decode_cert(tmp_cert_file_name)
    except Exception as e:
        print("Error decoding certificate:", e)
        return dict()
    finally:
        os.unlink(tmp_cert_file_name)


def get_srv_cert_0(host, port=443):
    try:
        cert_pem = ssl.get_server_certificate((host, port))
    except Exception as e:
        print("Error getting certificate:", e)
        return dict()
    tmp_cert_file_name = _get_tmp_cert_file_name(host, port)
    return _decode_cert(cert_pem, tmp_cert_file_name)


def get_srv_cert_1(host, port=443):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    context = ssl.SSLContext()
    ssl_sock = context.wrap_socket(sock, server_hostname=host)
    try:
        ssl_sock.connect((host, port))
    except Exception as e:
        print("Error connecting:\n", e)
        return dict()
    try:
        cert_der = ssl_sock.getpeercert(True)  # NOTE THE ARGUMENT!!!
    except Exception as e:
        print("Error getting cert:\n", e)
        return dict()
    tmp_cert_file_name = _get_tmp_cert_file_name(host, port)
    return _decode_cert(ssl.DER_cert_to_PEM_cert(cert_der), tmp_cert_file_name)


def main(argv):
    domain = "google.com"
    if argv:
        print("Using custom method")
        get_srv_cert_func = get_srv_cert_1
    else:
        print("Using regular method")
        get_srv_cert_func = get_srv_cert_0

    cert = get_srv_cert_func(domain)
    print("====== peer's certificate ======")
    try:
        print("Issued To:", dict(itertools.chain(*cert["subject"]))["commonName"])
        print("Issued By:", dict(itertools.chain(*cert["issuer"]))["commonName"])
        print("Valid From:", cert["notBefore"])
        print("Valid To:", cert["notAfter"])
        if (cert == None):
            print("no certificate")
    except Exception as e:
        print("Error getting certificate:", e)


if __name__ == "__main__":
    print("Python {:s} on {:s}\n".format(sys.version, sys.platform))
    main(sys.argv[1:])

Бележки:

• _get_tmp_cert_file_name: генерира името на временния файл (разположен в същия каталог като скрипта), който ще съхранява сертификата
• _decode_cert: записва сертификата във файла, след което декодира файла и връща получения dict
• get_srv_cert_0: получава сървъра за формуляр на сертификат, след което го декодира
• get_srv_cert_1: same thing that get_srv_cert_0 does, but "manually"
  • Its advantage is controlling the SSL context creation / manipulation (which I think was the main point of the question)
• main:
  • Gets the server certificate using one of the 2 methods above (based on an argument being / not being passed to the script)
  • Отпечатва данни за сертификат (вашият код с някои малки корекции)

Резултат:

(py35x64_test) e:\Work\Dev\StackOverflow\q050055935>"e:\Work\Dev\VEnvs\py35x64_test\Scripts\python.exe" code00.py
Python 3.5.4 (v3.5.4:3f56838, Aug  8 2017, 02:17:05) [MSC v.1900 64 bit (AMD64)] on win32

Using regular method
====== peer's certificate ======
Issued To: *.google.com
Issued By: Google Internet Authority G2
Valid From: Apr 10 18:58:05 2018 GMT
Valid To: Jul  3 18:33:00 2018 GMT

(py35x64_test) e:\Work\Dev\StackOverflow\q050055935>"e:\Work\Dev\VEnvs\py35x64_test\Scripts\python.exe" code00.py 1
Python 3.5.4 (v3.5.4:3f56838, Aug  8 2017, 02:17:05) [MSC v.1900 64 bit (AMD64)] on win32

Using custom method
====== peer's certificate ======
Issued To: *.google.com
Issued By: Google Internet Authority G2
Valid From: Apr 10 18:55:13 2018 GMT
Valid To: Jul  3 18:33:00 2018 GMT

Проверете [SO]: Как мога да декодирам SSL сертификат с помощта на python? (Отговорът на @CristiFati) само за декодиращата част.