support encryption (#60)

easytier/src/peers/encrypt/mod.rs

@@ -0,0 +1,34 @@
+use crate::tunnel::packet_def::ZCPacket;
+
+pub mod ring_aes_gcm;
+
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("packet is not encrypted")]
+    NotEcrypted,
+    #[error("packet is too short. len: {0}")]
+    PacketTooShort(usize),
+    #[error("decryption failed")]
+    DecryptionFailed,
+    #[error("encryption failed")]
+    EncryptionFailed,
+    #[error("invalid tag. tag: {0:?}")]
+    InvalidTag(Vec<u8>),
+}
+
+pub trait Encryptor: Send + Sync + 'static {
+    fn encrypt(&self, zc_packet: &mut ZCPacket) -> Result<(), Error>;
+    fn decrypt(&self, zc_packet: &mut ZCPacket) -> Result<(), Error>;
+}
+
+pub struct NullCipher;
+
+impl Encryptor for NullCipher {
+    fn encrypt(&self, _zc_packet: &mut ZCPacket) -> Result<(), Error> {
+        Ok(())
+    }
+
+    fn decrypt(&self, _zc_packet: &mut ZCPacket) -> Result<(), Error> {
+        Ok(())
+    }
+}