Add helper to get the hostname for ssl matching

Author: gabor-boros

rethinkdb/helpers.py

@@ -1,10 +1,19 @@
+import re
 import six
 
+
 def decode_utf8(string, encoding='utf-8'):
     if hasattr(string, 'decode'):
         return string.decode(encoding)
 
     return string
 
+
 def chain_to_bytes(*strings):
     return b''.join([six.b(string) if isinstance(string, six.string_types) else string for string in strings])
+
+
+def get_hostname_for_ssl_match(hostname):
+    match = re.match(r'^((?P<subdomain>[^\.]+)\.)?(?P<domain>[^\./]+\.[^/]+)/?.*$', hostname)
+    domain = match.group('domain')
+    return '*.{domain}'.format(domain=domain) if match.group('subdomain') else domain

tests/test_helpers.py

@@ -1,6 +1,6 @@
 import pytest
 from mock import Mock
-from rethinkdb.helpers import decode_utf8, chain_to_bytes
+from rethinkdb.helpers import decode_utf8, chain_to_bytes, get_hostname_for_ssl_match
 
 @pytest.mark.unit
 class TestDecodeUTF8Helper(object):
@@ -42,3 +42,24 @@ def test_mixed_chaining(self):
         result = chain_to_bytes('iron', ' ', b'man')
 
         assert result == expected_string
+
+
+@pytest.mark.unit
+class TestSSLMatchHostHostnameHelper(object):
+    def test_subdomain_replaced_to_star(self):
+        expected_string = '*.example.com'
+
+        result = get_hostname_for_ssl_match('test.example.com')
+
+        assert result == expected_string
+
+    def test_no_subdomain_to_replace(self):
+        expected_string = 'example.com'
+
+        result = get_hostname_for_ssl_match('example.com')
+
+        assert result == expected_string
+
+    def test_no_match(self):
+        with pytest.raises(AttributeError) as exc:
+            get_hostname_for_ssl_match('')