olm: Save and restore the olm account keys.

matrix/encryption.py

@@ -170,6 +170,21 @@ class Olm():
             with open(path, "rb") as f:
                 pickle = f.read()
                 account = Account.from_pickle(pickle)
-                return cls(server, account)
+                return cls(account)
+        except OlmAccountError as error:
+            raise EncryptionError(error)
+
+    @encrypt_enabled
+    def to_session_dir(self, server):
+        # type: (Server) -> None
+        account_file_name = "{}_{}.account".format(server.user,
+                                                   server.device_id)
+        session_path = server.get_session_path()
+        path = os.path.join(session_path, account_file_name)
+
+        try:
+            with open(path, "wb") as f:
+                pickle = self.account.pickle()
+                f.write(pickle)
         except OlmAccountError as error:
             raise EncryptionError(error)

matrix/events.py

@@ -89,6 +89,7 @@ class MatrixLoginEvent(MatrixEvent):
 
         if not self.server.olm:
             self.server.create_olm()
+            self.server.store_olm()
 
         self.server.sync()
 

matrix/server.py

@@ -158,7 +158,10 @@ class MatrixServer:
                        server=self.name,
                        device=self.device_id)
         W.prnt(self.server_buffer, message)
-        self.olm = Olm(self)
+        self.olm = Olm()
+
+    def store_olm(self):
+        self.olm.to_session_dir(self)
 
     def _create_options(self, config_file):
         options = [