From 1b4b9020e6d4de9bd6b4583442fdf326f88aac17 Mon Sep 17 00:00:00 2001
From: Alex Zenla <alex@edera.dev>
Date: Mon, 15 Apr 2024 03:03:17 +0000
Subject: [PATCH] chore: make idm magic value three bytes

---
 crates/daemon/src/idm.rs       | 28 ++++++++++++++++------------
 crates/krata/src/idm/client.rs |  8 ++++++--
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/crates/daemon/src/idm.rs b/crates/daemon/src/idm.rs
index ee788b9..1a440c3 100644
--- a/crates/daemon/src/idm.rs
+++ b/crates/daemon/src/idm.rs
@@ -22,6 +22,9 @@ use tokio::{
     task::JoinHandle,
 };
 
+const IDM_TX_QUEUE_LEN: usize = 100;
+const IDM_SNOOP_QUEUE_LEN: usize = 100;
+
 type BackendFeedMap = Arc<Mutex<HashMap<u32, Sender<IdmPacket>>>>;
 type ClientMap = Arc<Mutex<HashMap<u32, IdmClient>>>;
 
@@ -74,8 +77,8 @@ impl DaemonIdm {
     pub async fn new() -> Result<DaemonIdm> {
         let (service, tx_raw_sender, rx_receiver) =
             ChannelService::new("krata-channel".to_string(), None).await?;
-        let (tx_sender, tx_receiver) = channel(100);
-        let (snoop_sender, _) = broadcast::channel(100);
+        let (tx_sender, tx_receiver) = channel(IDM_TX_QUEUE_LEN);
+        let (snoop_sender, _) = broadcast::channel(IDM_SNOOP_QUEUE_LEN);
         let task = service.launch().await?;
         let clients = Arc::new(Mutex::new(HashMap::new()));
         let feeds = Arc::new(Mutex::new(HashMap::new()));
@@ -120,17 +123,17 @@ impl DaemonIdm {
                         if let Some(data) = data {
                             let buffer = buffers.entry(domid).or_insert_with_key(|_| BytesMut::new());
                             buffer.extend_from_slice(&data);
-                            if buffer.len() < 6 {
+                            if buffer.len() < 7 {
                                 continue;
                             }
 
-                            if buffer[0] != 0xff || buffer[1] != 0xff {
+                            if buffer[0] != 0xff || buffer[1] != 0xfe || buffer[2] != 0xff {
                                 buffer.clear();
                                 continue;
                             }
 
-                            let size = (buffer[2] as u32 | (buffer[3] as u32) << 8 | (buffer[4] as u32) << 16 | (buffer[5] as u32) << 24) as usize;
-                            let needed = size + 6;
+                            let size = (buffer[3] as u32 | (buffer[4] as u32) << 8 | (buffer[5] as u32) << 16 | (buffer[6] as u32) << 24) as usize;
+                            let needed = size + 7;
                             if buffer.len() < needed {
                                 continue;
                             }
@@ -165,14 +168,15 @@ impl DaemonIdm {
                 x = self.tx_receiver.recv() => match x {
                     Some((domid, packet)) => {
                         let data = packet.encode_to_vec();
-                        let mut buffer = vec![0u8; 6];
+                        let mut buffer = vec![0u8; 7];
                         let length = data.len() as u32;
                         buffer[0] = 0xff;
-                        buffer[1] = 0xff;
-                        buffer[2] = length as u8;
-                        buffer[3] = (length << 8) as u8;
-                        buffer[4] = (length << 16) as u8;
-                        buffer[5] = (length << 24) as u8;
+                        buffer[1] = 0xfe;
+                        buffer[2] = 0xff;
+                        buffer[3] = length as u8;
+                        buffer[4] = (length << 8) as u8;
+                        buffer[5] = (length << 16) as u8;
+                        buffer[6] = (length << 24) as u8;
                         buffer.extend_from_slice(&data);
                         self.tx_raw_sender.send((domid, buffer)).await?;
                         let _ = self.snoop_sender.send(DaemonIdmSnoopPacket { from: 0, to: domid, packet });
diff --git a/crates/krata/src/idm/client.rs b/crates/krata/src/idm/client.rs
index 3c0181b..f94d0f8 100644
--- a/crates/krata/src/idm/client.rs
+++ b/crates/krata/src/idm/client.rs
@@ -74,7 +74,11 @@ impl IdmBackend for IdmFileBackend {
             return Ok(IdmPacket::default());
         }
         let b2 = guard.get_inner_mut().read_u8().await?;
-        if b2 != 0xff {
+        if b2 != 0xfe {
+            return Ok(IdmPacket::default());
+        }
+        let b3 = guard.get_inner_mut().read_u8().await?;
+        if b3 != 0xff {
             return Ok(IdmPacket::default());
         }
         let size = guard.get_inner_mut().read_u32_le().await?;
@@ -92,7 +96,7 @@ impl IdmBackend for IdmFileBackend {
     async fn send(&mut self, packet: IdmPacket) -> Result<()> {
         let mut file = self.write.lock().await;
         let data = packet.encode_to_vec();
-        file.write_all(&[0xff, 0xff]).await?;
+        file.write_all(&[0xff, 0xfe, 0xff]).await?;
         file.write_u32_le(data.len() as u32).await?;
         file.write_all(&data).await?;
         Ok(())