refactor(tvix/nix-compat/wire): move magic bytes to worker_protocol r/7874

`primitive.rs` implements reading and writing primitive (fixed-length)
types in the wire format, used in the the nix daemon protocol and NAR
format.

Move worker-protocol specific magic bytes to worker_protocol.rs (and
possibly further split there once needed)

Change-Id: If681c01e9460294619f1d000229b81f0ac745810
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11377
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: picnoir picnoir <picnoir@alternativebit.fr>

3 files changed, 18 insertions, 16 deletions

diff --git a/tvix/nix-compat/src/wire/primitive.rs b/tvix/nix-compat/src/wire/primitive.rs
index 119053b89d..ee0f5fc427 100644
--- a/tvix/nix-compat/src/wire/primitive.rs
+++ b/tvix/nix-compat/src/wire/primitive.rs
@@ -4,13 +4,6 @@
 
 use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
 
-// LE-encoded nixc on 64 bits. Because why not.
-pub static MAGIC_HELLO: [u8; 8] = *b"cxin\0\0\0\0";
-// LE-encoded dxio on 64 bits. What's dxio? I have no clue.
-pub static MAGIC_HELLO_RESPONSE: [u8; 8] = *b"oixd\0\0\0\0";
-// LE-encoded protocol version.
-pub static PROTOCOL_VERSION: [u8; 8] = [0x23, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00];
-
 #[allow(dead_code)]
 /// Read a u64 from the AsyncRead (little endian).
 pub async fn read_u64<R: AsyncReadExt + Unpin>(r: &mut R) -> std::io::Result<u64> {
diff --git a/tvix/nix-compat/src/wire/worker_protocol.rs b/tvix/nix-compat/src/wire/worker_protocol.rs
index 77d5104250..c9d0553192 100644
--- a/tvix/nix-compat/src/wire/worker_protocol.rs
+++ b/tvix/nix-compat/src/wire/worker_protocol.rs
@@ -11,6 +11,13 @@ use crate::wire::primitive;
 
 use super::bytes::read_string;
 
+// LE-encoded nixc on 64 bits. Because why not.
+pub static MAGIC_HELLO: [u8; 8] = *b"cxin\0\0\0\0";
+// LE-encoded dxio on 64 bits. What's dxio? I have no clue.
+pub static MAGIC_HELLO_RESPONSE: [u8; 8] = *b"oixd\0\0\0\0";
+// LE-encoded protocol version.
+pub static PROTOCOL_VERSION: [u8; 8] = [0x23, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00];
+
 pub static STDERR_LAST: u64 = 0x616c7473;
 
 /// Max length of a Nix setting name/value. In bytes.
diff --git a/users/picnoir/tvix-daemon/src/main.rs b/users/picnoir/tvix-daemon/src/main.rs
index d18ff24713..46cb813e3e 100644
--- a/users/picnoir/tvix-daemon/src/main.rs
+++ b/users/picnoir/tvix-daemon/src/main.rs
@@ -127,15 +127,17 @@ where
     let mut magic_hello = vec![0; 8];
     conn.read_exact(&mut magic_hello).await?;
     debug!("Hello read");
-    if magic_hello != primitive::MAGIC_HELLO {
+    if magic_hello != worker_protocol::MAGIC_HELLO {
         Err(anyhow!(
             "Invalid client hello received: {:?}, expected {:?}",
             magic_hello,
-            primitive::MAGIC_HELLO
+            worker_protocol::MAGIC_HELLO
         ))
     } else {
-        conn.write_all(&primitive::MAGIC_HELLO_RESPONSE).await?;
-        conn.write_all(&primitive::PROTOCOL_VERSION).await?;
+        conn.write_all(&worker_protocol::MAGIC_HELLO_RESPONSE[..])
+            .await?;
+        conn.write_all(&worker_protocol::PROTOCOL_VERSION[..])
+            .await?;
         conn.flush().await?;
         debug!("Hello responded");
         let client_version = primitive::read_u64(&mut conn).await?;
@@ -192,16 +194,16 @@ where
 
 #[cfg(test)]
 mod integration_tests {
-    use nix_compat::wire::primitive;
+    use nix_compat::wire::worker_protocol;
     #[tokio::test]
     async fn test_init_handshake() {
         let mut test_conn = tokio_test::io::Builder::new()
-            .read(&primitive::MAGIC_HELLO)
-            .write(&primitive::MAGIC_HELLO_RESPONSE)
-            .write(&primitive::PROTOCOL_VERSION)
+            .read(&worker_protocol::MAGIC_HELLO)
+            .write(&worker_protocol::MAGIC_HELLO_RESPONSE)
+            .write(&worker_protocol::PROTOCOL_VERSION)
             // Let's say the client is in sync with the daemon
             // protocol-wise
-            .read(&primitive::PROTOCOL_VERSION)
+            .read(&worker_protocol::PROTOCOL_VERSION)
             // cpu affinity
             .read(&vec![0; 8])
             // reservespace