Implement version check & transmit more error info

1 files changed, 21 insertions, 1 deletions

diff --git a/src/proto.rs b/src/proto.rs
index 2db3f83..146211b 100644
--- a/src/proto.rs
+++ b/src/proto.rs
@@ -1,7 +1,7 @@
 use std::collections::{HashMap, VecDeque};
 use std::sync::Arc;
 
-use log::trace;
+use log::{error, trace};
 
 use futures::{AsyncReadExt, AsyncWriteExt};
 use kuska_handshake::async_std::BoxStreamWrite;
@@ -12,6 +12,10 @@ use async_trait::async_trait;
 
 use crate::error::*;
 
+/// Tag which is exchanged between client and server upon connection establishment
+/// to check that they are running compatible versions of Netapp
+pub const VERSION_TAG: [u8; 8] = [b'n', b'e', b't', b'a', b'p', b'p', 0x00, 0x04];
+
 /// Priority of a request (click to read more about priorities).
 ///
 /// This priority value is used to priorize messages
@@ -114,6 +118,10 @@ pub(crate) trait SendLoop: Sync {
 	where
 		W: AsyncWriteExt + Unpin + Send + Sync,
 	{
+		// Before anything, send version tag, which is checked in recv_loop
+		write.write_all(&VERSION_TAG[..]).await?;
+		write.flush().await?;
+
 		let mut sending = SendQueue::new();
 		let mut should_exit = false;
 		while !should_exit || !sending.is_empty() {
@@ -169,6 +177,7 @@ pub(crate) trait SendLoop: Sync {
 				}
 			}
 		}
+
 		let _ = write.goodbye().await;
 		Ok(())
 	}
@@ -189,6 +198,17 @@ pub(crate) trait RecvLoop: Sync + 'static {
 	where
 		R: AsyncReadExt + Unpin + Send + Sync,
 	{
+		let mut their_version_tag = [0u8; 8];
+		read.read_exact(&mut their_version_tag[..]).await?;
+		if their_version_tag != VERSION_TAG {
+			let msg = format!(
+				"Different netapp versions: {:?} (theirs) vs. {:?} (ours)",
+				their_version_tag, VERSION_TAG
+			);
+			error!("{}", msg);
+			return Err(Error::VersionMismatch(msg));
+		}
+
 		let mut receiving = HashMap::new();
 		loop {
 			trace!("recv_loop: reading packet");