问使用Python3.3SSL模块获取证书链

EN

openssl s_client -connect google.com:443

$ openssl s_client -connect google.com:443
CONNECTED(00000003)
depth=2 C = US, O = GeoTrust Inc., CN = GeoTrust Global CA
verify error:num=20:unable to get local issuer certificate
verify return:0
---
Certificate chain
 0 s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=*.google.com
   i:/C=US/O=Google Inc/CN=Google Internet Authority G2
 1 s:/C=US/O=Google Inc/CN=Google Internet Authority G2
   i:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
 2 s:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
   i:/C=US/O=Equifax/OU=Equifax Secure Certificate Authority
---

import socket

from ssl import SSLContext  # Modern SSL?
from ssl import HAS_SNI  # Has SNI?

from pprint import pprint

def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
                    ca_certs=None, server_hostname=None,
                    ssl_version=None):

    context = SSLContext(ssl_version)
    context.verify_mode = cert_reqs

    if ca_certs:
        try:
            context.load_verify_locations(ca_certs)
        # Py32 raises IOError
        # Py33 raises FileNotFoundError
        except Exception as e:  # Reraise as SSLError
            raise ssl.SSLError(e)

    if certfile:
        # FIXME: This block needs a test.
        context.load_cert_chain(certfile, keyfile)

    if HAS_SNI:  # Platform-specific: OpenSSL with enabled SNI
        return context.wrap_socket(sock, server_hostname=server_hostname)

    return context.wrap_socket(sock)

hostname = 'www.google.com'
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((hostname, 443))

sslSocket = ssl_wrap_socket(s,
                            ssl_version=2, 
                            cert_reqs=2, 
                            ca_certs='/usr/local/lib/python3.3/dist-packages/requests/cacert.pem', 
                            server_hostname=hostname)

pprint(sslSocket.getpeercert())
s.close()

{'issuer': ((('countryName', 'US'),),
            (('organizationName', 'Google Inc'),),
            (('commonName', 'Google Internet Authority G2'),)),
 'notAfter': 'Sep 25 15:09:31 2014 GMT',
 'notBefore': 'Sep 25 15:09:31 2013 GMT',
 'serialNumber': '13A87ADB3E733D3B',
 'subject': ((('countryName', 'US'),),
             (('stateOrProvinceName', 'California'),),
             (('localityName', 'Mountain View'),),
             (('organizationName', 'Google Inc'),),
             (('commonName', 'www.google.com'),)),
 'subjectAltName': (('DNS', 'www.google.com'),),
 'version': 3}