Question

I’m not sure how to word this exactly but I have a script that downloads an SSL certificate from a web server to check it’s expiration date.

To do this, I need to download the CA certificates. Currently I write them to a temporary file in the /tmp directory and read it back later but I am sure there must be a way to do this without writing to disk.

Here’s the portion that’s downloading the certificates

CA_FILE = '/tmp/ca_certs.txt'

root_cert = urllib.urlopen('https://www.cacert.org/certs/root.txt')
class3_cert = urllib.urlopen('https://www.cacert.org/certs/class3.txt')

temp_file = open(CA_FILE, 'w')    
temp_file.write(root_cert.read())
temp_file.write(class3_cert.read())
temp_file.close()

EDIT

Here’s the portion that uses the file to get the certificate

 s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 ssl_sock = ssl.wrap_socket(s, ca_certs=CA_FILE, cert_reqs=ssl.CERT_REQUIRED)
 ssl_sock.connect(('mail.google.com', 443))

 date = ssl_sock.getpeercert()['notAfter']

Answer 1

the response from urllib is a file object. just use those wherever you are using the actual files instead. This is assuming that the code that consumes the file objects doesn’t need to write to them of course.