use workspace, prepare for config server and gui (#48)

easytier/src/peer_center/mod.rs

@@ -0,0 +1,20 @@
+// peer_center is used to collect peer info into one peer node.
+// the center node is selected with the following rules:
+// 1. has smallest peer id
+// 2. TODO: has allow_to_be_center peer feature
+// peer center is not guaranteed to be stable and can be changed when peer enter or leave.
+// it's used to reduce the cost to exchange infos between peers.
+
+pub mod instance;
+mod server;
+mod service;
+
+#[derive(thiserror::Error, Debug, serde::Deserialize, serde::Serialize)]
+pub enum Error {
+    #[error("Digest not match, need provide full peer info to center server.")]
+    DigestMismatch,
+    #[error("Not center server")]
+    NotCenterServer,
+}
+
+pub type Digest = u64;