如何用Python SSL与OpenSSL获取指定站点完整SSL证书链（解决SNI问题）

我正在研究互联网上不受信任根证书的使用要求，目前在SSL证书链检测环节遇到问题。

我原本使用以下函数检测指定证书：

def _get_root_cert(link: str):
    cert = ssl.get_server_certificate((link.split('//')[1], 443))
    x509 = crypto.load_certificate(crypto.FILETYPE_PEM, cert.encode())
    return x509.get_issuer().get_components()[2][1].decode()

该代码运行正常，但针对部分站点（如mintrans.ryazan.gov.ru），我得到的是“No-Sni证书名”而非预期的Russian Trusted CA。因此我需要获取完整的SSL证书链，但尝试的代码未达到预期效果，恳请各位提供帮助。

我用于检测证书链的实验代码如下：

import socket
import ssl
import base64
import binascii

hostname: str = 'https://mintrans.ryazan.gov.ru'

# Set up a socket connection to the site
context = ssl.create_default_context()
context.check_hostname = False
context.verify_mode = ssl.CERT_NONE

with socket.create_connection((hostname, 443)) as sock:
    with context.wrap_socket(sock, server_hostname=hostname) as sock:
        # Get the certificate chain
        cert_chain = sock.getpeercert(True)

# cert_chain_b64 = base64.b64encode(cert_chain).decode('utf-8')
# cert_chain_bytes = binascii.a2b_base64(cert_chain_b64)
# cert_chain_text = cert_chain_bytes.decode('utf-8')

cert_chain_text = None

try:
    cert_chain_text = cert_chain.decode('utf-8')
except UnicodeDecodeError:
    pass

if cert_chain_text is None:
    try:
        cert_chain_text = cert_chain.decode('latin-1')
    except UnicodeDecodeError:
        pass

if cert_chain_text is None:
    try:
        cert_chain_text = cert_chain.decode('windows-1252')
    except UnicodeDecodeError:
        pass

if cert_chain_text is None:
    # Handle the error if none of the encodings work
    print('Unable to decode certificate chain')

print(cert_chain_text)

内容的提问来源于stack exchange，提问作者sigseg5