Middleware to do the learning and verifying seed nodes.

nucypher/utilities/sandbox/middleware.py

@@ -25,14 +25,45 @@ class MockRestMiddleware(RestMiddleware):
         return self._get_mock_client_by_port(port)
 
     def _get_mock_client_by_port(self, port):
+        ursula = self._get_ursula_by_port(port)
+        rest_app = ursula.rest_app
+        mock_client = TestClient(rest_app)
+        return mock_client
+
+    def _get_ursula_by_port(self, port):
         try:
-            ursula = TEST_KNOWN_URSULAS_CACHE[port]
-            rest_app = ursula.rest_app
-            mock_client = TestClient(rest_app)
+            return TEST_KNOWN_URSULAS_CACHE[port]
         except KeyError:
             raise RuntimeError(
                 "Can't find an Ursula with port {} - did you spin up the right test ursulas?".format(port))
-        return mock_client
+
+    def learn_from_seednode(self, seednode_metadata, timeout=3, accept_federated_only=False):
+        # Pre-fetch certificate
+        self.log.info("Fetching bootnode {} TLS certificate".format(seednode_metadata.checksum_address))
+
+        certificate, filepath = self._get_certificate(seednode_metadata.rest_host, seednode_metadata.rest_port)
+
+        potential_seed_node = Ursula.from_rest_url(self,
+                                                   seednode_metadata.rest_host,
+                                                   seednode_metadata.rest_port,
+                                                   certificate_filepath=filepath,
+                                                   federated_only=True)  # TODO: 466
+
+        if not seednode_metadata.checksum_address == potential_seed_node.checksum_public_address:
+            raise potential_seed_node.SuspiciousActivity(
+                "This seed node has a different wallet address: {} (was hoping for {}).  Are you sure this is a seed node?".format(
+                    potential_seed_node.checksum_public_address,
+                    bootnode.checksum_address))
+        try:
+            potential_seed_node.verify_node(self, accept_federated_only=accept_federated_only)
+        except potential_seed_node.InvalidNode:
+            raise  # TODO: What if our seed node fails verification?
+
+        return potential_seed_node
+
+    def _get_certificate(self, hostname, port):
+        ursula = self._get_ursula_by_port(port)
+        return ursula.certificate, ursula.certificate_filepath
 
     def consider_arrangement(self, arrangement):
         mock_client = self._get_mock_client_by_ursula(arrangement.ursula)