+ * Returns: ttt_server_get_client_from_username(server, username)
+ *
+ * Locking: See ttt_server_get_client_from_username
+ *
+ * Errors: See ttt_server_get_client_from_username
+ */
+ttt_error_t
+ttt_server_verify_username (ttt_server_t *server,
+ const char *username);
+
+/* Points *client to the client with the supplied username, else
+ * leaves *client unhanged.
+ *
+ * Returns: TTT_ERROR_NONE, else TTT_ERROR_NO_USER if username not
+ * found.
+ *
+ * Locking: The server mutex will be acquired and held throughout the
+ * execution of this function. Each client mutex may also be acquired
+ * and held by functions called during the execution of this function.
+ *
+ * Errors: If an error such as an IO error occurs, this function will
+ * not return.
+ */
+ttt_error_t
+ttt_server_get_client_from_username (ttt_server_t *server,
+ const char *username,
+ ttt_client_t **client);
+
+/* Adds an invitation
+ *
+ * Locking: The server mutex will be acquired and held throughout the
+ * execution of this function. Each client mutex may also be acquired
+ * and held by functions called during the execution of this function.
+ *
+ * Errors: If an error such as an IO error occurs, this function will
+ * not return.
+ */
+ttt_error_t
+ttt_server_add_invite (ttt_server_t *server,
+ ttt_client_t *actor,
+ ttt_client_t *invitee);
+
+/* Removes an invitation
+ *
+ * Returns: TTT_ERROR_NONE, else TTT_ERROR_NO_INVITE if no invite
+ * found.
+ *