Add server TLS context factory

synapse/crypto/context_factory.py

@@ -0,0 +1,23 @@
+from twisted.internet import reactor, ssl
+from OpenSSL import SSL
+
+
+class ServerContextFactory(ssl.ContextFactory):
+    """Factory for PyOpenSSL SSL contexts that are used to handle incoming
+    connections and to make connections to remote servers."""
+
+    def __init__(self, config):
+        self._context = SSL.Context(SSL.SSLv23_METHOD)
+        self.configure_context(self._context, config)
+
+    @staticmethod
+    def configure_context(context, config):
+        context.set_options(SSL.OP_NO_SSLv2 | SSL.OP_NO_SSLv3)
+        context.use_certificate(config.tls_certificate)
+        context.use_privatekey(config.tls_private_key)
+        context.load_tmp_dh(config.tls_dh_params_path)
+        context.set_cipher_list("!ADH:HIGH+kEDH:!AECDH:HIGH+kEECDH")
+
+    def getContext(self):
+        return self._context
+