proto(utils): add TransientDigest trait (#2071)

easytier/src/proto/mod.rs

@@ -12,6 +12,7 @@ pub mod web;
 
 #[cfg(test)]
 pub mod tests;
+pub mod utils;
 
 const DESCRIPTOR_POOL_BYTES: &[u8] =
     include_bytes!(concat!(env!("OUT_DIR"), "/file_descriptor_set.bin"));

easytier/src/proto/utils.rs

@@ -0,0 +1,20 @@
+use prost::Message;
+use sha2::{Digest, Sha256};
+
+/// Generates a stable digest strictly within the lifecycle of the current process.
+///
+/// ⚠️ WARNING:
+/// - This digest is ONLY guaranteed to be deterministic within a **single process and the exact same binary build**.
+pub trait TransientDigest: Message {
+    fn digest(&self) -> [u8; 32]
+    where
+        Self: Sized,
+    {
+        let buf = self.encode_to_vec();
+        let mut hasher = Sha256::new();
+        hasher.update(buf);
+        hasher.finalize().into()
+    }
+}
+
+impl<S: Message> TransientDigest for S {}