def subproc(cmd):

from subprocess import Popen, PIPE, STDOUT

proc = Popen(cmd, stdout=PIPE, stderr=STDOUT, shell=True)

status = proc.wait()

output = proc.stdout.read()

return status, output

def strip_to_x509_cert(certfile_contents, outfile=None):

m = re.search(br"^([-]+BEGIN CERTIFICATE[-]+[\r]*\n"

br".*[\r]*^[-]+END CERTIFICATE[-]+)$",

certfile_contents, re.MULTILINE | re.DOTALL)

if not m:

return None

else:

tn = tempfile.mktemp()

with open(tn, "wb") as fp:

fp.write(m.group(1) + b"\n")

try:

tn2 = (outfile or tempfile.mktemp())

status, output = subproc(r'openssl x509 -in "%s" -out "%s"' %

(tn, tn2))

if status != 0:

raise RuntimeError('OpenSSL x509 failed with status %s and '

'output: %r' % (status, output))

with open(tn2, 'rb') as fp:

data = fp.read()

os.unlink(tn2)

return data

finally:

os.unlink(tn)

if sys.platform.startswith("win"):

tfile = tempfile.mktemp()

with open(tfile, "w") as fp:

fp.write("quit\n")

try:

status, output = subproc(

'openssl s_client -connect "%s:%s" -showcerts < "%s"' %

(host, port, tfile))

finally:

os.unlink(tfile)

else:

status, output = subproc(

'openssl s_client -connect "%s:%s" -showcerts < /dev/null' %

(host, port))

if status != 0:

raise RuntimeError('OpenSSL connect failed with status %s and '

'output: %r' % (status, output))

certtext = strip_to_x509_cert(output)

if not certtext:

raise ValueError("Invalid response received from server at %s:%s" %

(host, port))