Helper functions to extract redirect chains and cert SAN

redirect_certs_helpers.py

import re
import ssl
import socket
import requests
import urllib3
from OpenSSL import crypto

urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)


def certificate_san(site, port=443):
    site = _strip_schema(site)

    context = ssl.create_default_context()
    context.check_hostname = False
    with socket.create_connection((site, port)) as sock:
        with context.wrap_socket(sock, server_hostname=site) as ssock:
            cert = ssock.getpeercert(binary_form=True)
            x509 = crypto.load_certificate(crypto.FILETYPE_ASN1, cert)
            san_list = []
            for i in range(x509.get_extension_count()):
                ext = x509.get_extension(i)
                if "subjectAltName" in ext.get_short_name().decode("utf-8"):
                    san_list.extend(str(ext).split(", "))

            return san_list


def redirect_chain(url):
    url = _ensure_https(url)

    chain = [url]
    while True:
        response = requests.get(url, verify=False, allow_redirects=False)
        url = response.headers.get("Location")

        if url is None:
            break
        chain.append(url)

    return chain


def final_url(url):
    url = _ensure_https(url)

    response = requests.get(url, verify=False)
    return response.url


def _ensure_https(url):
    if not "https://" in url:
        return "https://" + url
    return url


def _strip_schema(url):
    return re.sub("^https://", "", url)