mitmproxy/test/netlib/tools/getcertnames

#!/usr/bin/env python
import sys
sys.path.insert(0, "../../")
from netlib import tcp


def get_remote_cert(host, port, sni):
    c = tcp.TCPClient((host, port))
    c.connect()
    c.convert_to_ssl(sni=sni)
    return c.cert

if len(sys.argv) > 2:
    port = int(sys.argv[2])
else:
    port = 443
if len(sys.argv) > 3:
    sni = sys.argv[3]
else:
    sni = None

cert = get_remote_cert(sys.argv[1], port, sni)
print("CN:", cert.cn)
if cert.altnames:
    print("SANs:")
    for i in cert.altnames:
        print("\t", i)