import ssl, socket, traceback, sys

ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
ctx.verify_mode = ssl.CERT_REQUIRED
ctx.check_hostname = True
ctx.load_default_certs()

incoming, outgoing = ssl.MemoryBIO(), ssl.MemoryBIO()

host = 'bugs.python.org'
get=b'GET / HTTP/1.1\r\nHost: bugs.python.org\r\nConnection: close\r\n\r\n'

# create the SSLObject for the client side of SSL.

sslobj = ctx.wrap_bio(incoming, outgoing, server_hostname=host)

# connect the socket and make the initial TCP connection

sock = socket.create_connection((host, 443))

# start the handshake by attempting to encrypt the get request

while True:
    try:
        sslobj.write(get)
        break # exit the loop if the write succeeds.
    except ssl.SSLWantReadError:
        # we expect this as handshake data must be exchanged
        # show the buffers' state
        print('SSLWantRead exception')
        print((incoming.pending, outgoing.pending))
        sock.sendall(outgoing.read()) # send any outgoing data
        data = sock.recv(2048)
        incoming.write(data)
        print((incoming.pending, outgoing.pending))

print((incoming.pending, outgoing.pending))
sock.sendall(outgoing.read())

# Now the handshake is finished. The peer's certificate should
# be available.
try:
    print('Attempting to retrieve server cert')
    cert = sslobj.getpeercert(False)
except:
    # unfortunately, this raises a ValueError exception
    traceback.print_exc(file=sys.stdout)

# show the buffers' state before and after do_handshake call

print('Before do_handshake()')
print((incoming.pending, outgoing.pending))

sslobj.do_handshake()

print('After do_handshake()')
print((incoming.pending, outgoing.pending))

# no outward changes have occured because of the do_handshake() call.
# In particular, a handshake has not begun.
# However, now the getpeercert() call succeeds.

cert = sslobj.getpeercert(False)
print(cert)

# close the connection, we don't really care about the response
try:
    sslobj.unwrap()
except:
    pass

print('After ssl shutdown')
print((incoming.pending, outgoing.pending))
sock.sendall(outgoing.read())
sock.close()