Improve certificate check to support SNI (#71)

* Fix the certificate check to support SNI
* Better tests for the certificate check
* Activate verbose output when running make test
* Add commenting on the spider test

Makefile

@@ -44,5 +44,5 @@ test: dockerimage
 	docker run --rm -ti \
 		--entrypoint "python3" \
 		$(IMAGE) \
-		-m unittest discover -p '*_test.py'
+		-m unittest discover -p '*_test.py' -v
 

checks/certificate.py

@@ -4,6 +4,7 @@ Gathers information on the TLS/SSL certificate used by a server
 
 from urllib.parse import urlparse
 import logging
+import socket
 import ssl
 from datetime import datetime
 from datetime import timezone
@@ -36,8 +37,22 @@ class Checker(AbstractChecker):
         }
 
         parsed = urlparse(url)
+        port = 443
+        if parsed.port is not None:
+            port = parsed.port
+
+        try:
+            #cert = ssl.get_server_certificate((parsed.hostname, port))
+
+            context = ssl.create_default_context()
+
+            # get certificate with SNI
+            with socket.create_connection((parsed.hostname, port)) as sock:
+                with context.wrap_socket(sock, server_hostname=parsed.hostname) as sslsock:
+                    der_cert = sslsock.getpeercert(True)
+                    cert = ssl.DER_cert_to_PEM_cert(der_cert)
+
             try:
-            cert = ssl.get_server_certificate((parsed.hostname, 443))
                 x509 = crypto.load_certificate(crypto.FILETYPE_PEM, cert)
                 result['serial_number'] = str(x509.get_serial_number())
 
@@ -51,6 +66,11 @@ class Checker(AbstractChecker):
                 # decode and convert from bytes to unicode
                 result['subject'] = dict([tuple(map(lambda x: x.decode('utf-8'), tup)) for tup in x509.get_subject().get_components()])
                 result['issuer']  = dict([tuple(map(lambda x: x.decode('utf-8'), tup)) for tup in x509.get_issuer().get_components()])
+            except Exception as e:
+                result['exception'] = {
+                    'type': str(type(e)),
+                    'message': str(e),
+                }
             
         except Exception as e:
             result['exception'] = {

checks/certificate_test.py

@@ -1,10 +1,13 @@
 from checks import certificate
 from checks.config import Config
+
 import unittest
+from pprint import pprint
 
 class TestCertificateChecker(unittest.TestCase):
 
     def test_google(self):
+        """Load cert from a site that should work"""
         url = 'https://www.google.com/'
         config = Config(urls=[url])
         checker = certificate.Checker(config=config, previous_results={})
@@ -14,6 +17,7 @@ class TestCertificateChecker(unittest.TestCase):
         self.assertEqual(result[url]['issuer']['O'], 'Google Trust Services')
 
     def test_kaarst(self):
+        """Real-workd example"""
         url = 'https://www.gruenekaarst.de/'
         config = Config(urls=[url])
         checker = certificate.Checker(config=config, previous_results={})
@@ -22,6 +26,37 @@ class TestCertificateChecker(unittest.TestCase):
         self.assertIsNone(result[url]['exception'])
         self.assertEqual(result[url]['issuer']['O'], 'COMODO CA Limited')
 
+    def test_tls_v_1_0(self):
+        """Load a certificate for a TLS v1.0 server"""
+        url = 'https://tls-v1-0.badssl.com:1010/'
+        config = Config(urls=[url])
+        checker = certificate.Checker(config=config, previous_results={})
+        result = checker.run()
+        self.assertIn(url, result)
+        self.assertIsNone(result[url]['exception'])
+        self.assertEqual(result[url]['subject']['CN'], '*.badssl.com')
+
+    def test_tls_v_1_1(self):
+        """Load a certificate for a TLS v1.1 server"""
+        url = 'https://tls-v1-1.badssl.com:1011/'
+        config = Config(urls=[url])
+        checker = certificate.Checker(config=config, previous_results={})
+        result = checker.run()
+        self.assertIn(url, result)
+        self.assertIsNone(result[url]['exception'])
+        self.assertEqual(result[url]['subject']['CN'], '*.badssl.com')
+
+    def test_tls_v_1_2(self):
+        """Load a certificate for a TLS v1.2 server"""
+        url = 'https://tls-v1-2.badssl.com:1012/'
+        config = Config(urls=[url])
+        checker = certificate.Checker(config=config, previous_results={})
+        result = checker.run()
+        self.assertIn(url, result)
+        self.assertIsNone(result[url]['exception'])
+        self.assertEqual(result[url]['subject']['CN'], '*.badssl.com')
+
+
 
 if __name__ == '__main__':
     unittest.main()

spider/spider_test.py

@@ -1,12 +1,19 @@
 import unittest
+from pprint import pprint
 
 from spider.spider import check_and_rate_site
 
-from pprint import pprint
+class TestSpider(unittest.TestCase):
 
-class TestSpiderr(unittest.TestCase):
+    """
+    Simply calls the spider.check_and_rate_site function
+    with httpbin.org URLs. We don't assert a lot here,
+    but at least make sure that most of our code is executed
+    in tests.
+    """
 
-    def test_url1(self):
+    def test_html(self):
+        """Loads a simple HTML web page"""
 
         entry = {
             "url": "https://httpbin.org/html",