P2P: always send/expect network magic bytes

Ash-L2L · Ash-L2L · commit cab8d851df18 · 2025-11-08T00:00:38.000+08:00
diff --git a/lib/net/mod.rs b/lib/net/mod.rs
@@ -186,6 +186,7 @@ const fn seed_node_addrs(network: Network) -> &'static [SocketAddr] {
 pub struct Net {
     pub server: Endpoint,
     archive: Archive,
+    network: Network,
     state: State,
     active_peers: Arc<RwLock<HashMap<SocketAddr, PeerConnectionHandle>>>,
     // None indicates that the stream has ended
@@ -280,6 +281,7 @@ impl Net {
         let connection_ctxt = PeerConnectionCtxt {
             env,
             archive: self.archive.clone(),
+            network: self.network,
             state: self.state.clone(),
         };
 
@@ -358,6 +360,7 @@ impl Net {
         let net = Net {
             server,
             archive,
+            network,
             state,
             active_peers,
             peer_info_tx,
@@ -430,7 +433,7 @@ impl Net {
                         remote_address,
                     }
                 })?;
-                Connection::from(raw_conn)
+                Connection::new(raw_conn, self.network)
             }
             None => {
                 tracing::debug!("server endpoint closed");
@@ -462,6 +465,7 @@ impl Net {
         let connection_ctxt = PeerConnectionCtxt {
             env,
             archive: self.archive.clone(),
+            network: self.network,
             state: self.state.clone(),
         };
         let (connection_handle, info_rx) =
diff --git a/lib/net/peer/error.rs b/lib/net/peer/error.rs
@@ -71,10 +71,14 @@ pub(in crate::net::peer) mod connection {
 
     #[derive(Debug, Error)]
     pub enum Receive {
+        #[error("received incorrect magic: {}", hex::encode(.0))]
+        BadMagic(crate::net::peer::message::MagicBytes),
         #[error("bincode error")]
         Bincode(#[from] bincode::Error),
         #[error("connection error")]
         Connection(#[from] quinn::ConnectionError),
+        #[error("failed to read magic bytes")]
+        ReadMagic(#[source] quinn::ReadExactError),
         #[error("read to end error")]
         ReadToEnd(#[from] quinn::ReadToEndError),
     }
diff --git a/lib/net/peer/message.rs b/lib/net/peer/message.rs
@@ -7,9 +7,29 @@ use serde::{Deserialize, Serialize};
 
 use crate::{
     net::peer::{PeerState, PeerStateId},
-    types::{AuthorizedTransaction, BlockHash, Body, Header, Tip, Txid},
+    types::{
+        AuthorizedTransaction, BlockHash, Body, Header, Network, Tip, Txid,
+    },
 };
 
+pub const MAGIC_BYTES_LEN: usize = 4;
+
+pub type MagicBytes = [u8; MAGIC_BYTES_LEN];
+
+pub const fn magic_bytes(network: Network) -> MagicBytes {
+    // First 4 bytes are the US-TTY (LSB Right) Baudot–Murray code for "THNDR".
+    // Rightmost bits of the 4th byte is the network identifier.
+    let b0 = 0b1000_0101;
+    let b1 = 0b0001_1000;
+    let b2 = 0b1001_0101;
+    let mut b3 = 0b0000_0000;
+    match network {
+        Network::Regtest => (),
+        Network::Signet => b3 |= 0b0000_0001,
+    }
+    [b0, b1, b2, b3]
+}
+
 #[derive(BorshSerialize, Clone, Debug, Deserialize, Serialize)]
 pub struct Heartbeat(pub PeerState);
 
diff --git a/lib/net/peer/mod.rs b/lib/net/peer/mod.rs
@@ -18,7 +18,7 @@ use tokio::{spawn, task::JoinHandle, time::Duration};
 use crate::{
     archive::Archive,
     state::State,
-    types::{AuthorizedTransaction, Hash, Tip, Version, hash, schema},
+    types::{AuthorizedTransaction, Hash, Network, Tip, Version, hash, schema},
 };
 
 mod channel_pool;
@@ -140,6 +140,7 @@ where
 #[derive(Clone)]
 pub struct Connection {
     pub(in crate::net) inner: quinn::Connection,
+    pub network: Network,
 }
 
 impl Connection {
@@ -154,14 +155,25 @@ impl Connection {
         self.inner.remote_address()
     }
 
-    pub async fn new(
+    pub fn new(connection: quinn::Connection, network: Network) -> Self {
+        Self {
+            inner: connection,
+            network,
+        }
+    }
+
+    pub async fn from_connecting(
         connecting: quinn::Connecting,
+        network: Network,
     ) -> Result<Self, quinn::ConnectionError> {
         let addr = connecting.remote_address();
         tracing::trace!(%addr, "connecting to peer");
         let connection = connecting.await?;
         tracing::info!(%addr, "connected successfully to peer");
-        Ok(Self { inner: connection })
+        Ok(Self {
+            inner: connection,
+            network,
+        })
     }
 
     async fn receive_request(
@@ -170,6 +182,15 @@ impl Connection {
     {
         let (tx, mut rx) = self.inner.accept_bi().await?;
         tracing::trace!(recv_id = %rx.id(), "Receiving request");
+        let mut magic_bytes = [0u8; message::MAGIC_BYTES_LEN];
+        rx.read_exact(&mut magic_bytes)
+            .await
+            .map_err(error::connection::Receive::ReadMagic)?;
+        if magic_bytes != message::magic_bytes(self.network) {
+            return Err(
+                error::connection::Receive::BadMagic(magic_bytes).into()
+            );
+        }
         let msg_bytes = rx.read_to_end(Connection::READ_REQUEST_LIMIT).await?;
         let msg: RequestMessage = bincode::deserialize(&msg_bytes)?;
         tracing::trace!(
@@ -191,8 +212,9 @@ impl Connection {
             "Sending heartbeat"
         );
         let message = RequestMessageRef::from(heartbeat);
-        let message = bincode::serialize(&message)?;
-        send.write_all(&message).await.map_err(|err| {
+        let mut message_buf = message::magic_bytes(self.network).to_vec();
+        bincode::serialize_into::<&mut Vec<_>, _>(&mut message_buf, &message)?;
+        send.write_all(&message_buf).await.map_err(|err| {
             error::connection::Send::Write {
                 stream_id: send.id(),
                 source: err,
@@ -203,10 +225,20 @@ impl Connection {
     }
 
     async fn receive_response(
+        network: Network,
         mut recv: RecvStream,
         read_response_limit: NonZeroUsize,
     ) -> ResponseResult {
         tracing::trace!(recv_id = %recv.id(), "Receiving response");
+        let mut magic_bytes = [0u8; message::MAGIC_BYTES_LEN];
+        recv.read_exact(&mut magic_bytes)
+            .await
+            .map_err(error::connection::Receive::ReadMagic)?;
+        if magic_bytes != message::magic_bytes(network) {
+            return Err(
+                error::connection::Receive::BadMagic(magic_bytes).into()
+            );
+        }
         let response_bytes =
             recv.read_to_end(read_response_limit.get()).await?;
         let response: ResponseMessage = bincode::deserialize(&response_bytes)?;
@@ -230,40 +262,52 @@ impl Connection {
             "Sending request"
         );
         let message = RequestMessageRef::from(request);
-        let message = bincode::serialize(&message)?;
-        send.write_all(&message).await.map_err(|err| {
+        let mut message_buf = message::magic_bytes(self.network).to_vec();
+        bincode::serialize_into::<&mut Vec<_>, _>(&mut message_buf, &message)?;
+        send.write_all(&message_buf).await.map_err(|err| {
             error::connection::Send::Write {
                 stream_id: send.id(),
                 source: err,
             }
         })?;
         send.finish()?;
-        Ok(Self::receive_response(recv, read_response_limit).await)
+        Ok(
+            Self::receive_response(self.network, recv, read_response_limit)
+                .await,
+        )
     }
 
+    // Send a pre-serialized response, where the response does not include
+    // magic bytes
     async fn send_serialized_response(
+        network: Network,
         mut response_tx: SendStream,
         serialized_response: &[u8],
     ) -> Result<(), error::connection::SendResponse> {
         tracing::trace!(
             send_id = %response_tx.id(),
             "Sending response"
         );
-        response_tx
-            .write_all(serialized_response)
-            .await
-            .map_err(|err| {
-                {
-                    error::connection::Send::Write {
-                        stream_id: response_tx.id(),
-                        source: err,
-                    }
+        async {
+            response_tx
+                .write_all(&message::magic_bytes(network))
+                .await?;
+            response_tx.write_all(serialized_response).await
+        }
+        .await
+        .map_err(|err| {
+            {
+                error::connection::Send::Write {
+                    stream_id: response_tx.id(),
+                    source: err,
                 }
-                .into()
-            })
+            }
+            .into()
+        })
     }
 
     async fn send_response(
+        network: Network,
         mut response_tx: SendStream,
         response: ResponseMessage,
     ) -> Result<(), error::connection::SendResponse> {
@@ -272,8 +316,9 @@ impl Connection {
             send_id = %response_tx.id(),
             "Sending response"
         );
-        let response_bytes = bincode::serialize(&response)?;
-        response_tx.write_all(&response_bytes).await.map_err(|err| {
+        let mut message_buf = message::magic_bytes(network).to_vec();
+        bincode::serialize_into::<&mut Vec<_>, _>(&mut message_buf, &response)?;
+        response_tx.write_all(&message_buf).await.map_err(|err| {
             {
                 error::connection::Send::Write {
                     stream_id: response_tx.id(),
@@ -285,15 +330,10 @@ impl Connection {
     }
 }
 
-impl From<quinn::Connection> for Connection {
-    fn from(inner: quinn::Connection) -> Self {
-        Self { inner }
-    }
-}
-
 pub struct ConnectionContext {
     pub env: sneed::Env,
     pub archive: Archive,
+    pub network: Network,
     pub state: State,
 }
 
@@ -427,7 +467,8 @@ pub fn connect(
         let status_repr = status_repr.clone();
         let info_tx = info_tx.clone();
         move || async move {
-            let connection = Connection::new(connecting).await?;
+            let connection =
+                Connection::from_connecting(connecting, ctxt.network).await?;
             status_repr.store(
                 PeerConnectionStatus::Connected.as_repr(),
                 atomic::Ordering::SeqCst,
diff --git a/lib/net/peer/task.rs b/lib/net/peer/task.rs
@@ -609,7 +609,8 @@ impl ConnectionTask {
             }
             (_, _) => ResponseMessage::NoBlock { block_hash },
         };
-        let () = Connection::send_response(response_tx, resp).await?;
+        let () =
+            Connection::send_response(ctxt.network, response_tx, resp).await?;
         Ok(())
     }
 
@@ -661,6 +662,7 @@ impl ConnectionTask {
         match validate_tx_result {
             Err(err) => {
                 Connection::send_response(
+                    ctxt.network,
                     response_tx,
                     ResponseMessage::TransactionRejected(txid),
                 )
@@ -669,6 +671,7 @@ impl ConnectionTask {
             }
             Ok(_) => {
                 Connection::send_response(
+                    ctxt.network,
                     response_tx,
                     ResponseMessage::TransactionAccepted(txid),
                 )
@@ -844,8 +847,10 @@ impl ConnectionTask {
                     serialized_response,
                     response_tx,
                 }) => {
+                    let network = ctxt.network;
                     self.mailbox_tx.send_response_spawner.spawn(async move {
                         Connection::send_serialized_response(
+                            network,
                             response_tx,
                             &serialized_response,
                         )

Original file line number	Diff line number	Diff line change
`@@ -609,7 +609,8 @@ impl ConnectionTask {`
`609`	`609`	`}`
`610`	`610`	`(_, _) => ResponseMessage::NoBlock { block_hash },`
`611`	`611`	`};`
`612`		`- let () = Connection::send_response(response_tx, resp).await?;`
	`612`	`+ let () =`
	`613`	`+ Connection::send_response(ctxt.network, response_tx, resp).await?;`
`613`	`614`	`Ok(())`
`614`	`615`	`}`
`615`	`616`
`@@ -661,6 +662,7 @@ impl ConnectionTask {`
`661`	`662`	`match validate_tx_result {`
`662`	`663`	`Err(err) => {`
`663`	`664`	`Connection::send_response(`
	`665`	`+ ctxt.network,`
`664`	`666`	`response_tx,`
`665`	`667`	`ResponseMessage::TransactionRejected(txid),`
`666`	`668`	`)`
`@@ -669,6 +671,7 @@ impl ConnectionTask {`
`669`	`671`	`}`
`670`	`672`	`Ok(_) => {`
`671`	`673`	`Connection::send_response(`
	`674`	`+ ctxt.network,`
`672`	`675`	`response_tx,`
`673`	`676`	`ResponseMessage::TransactionAccepted(txid),`
`674`	`677`	`)`
`@@ -844,8 +847,10 @@ impl ConnectionTask {`
`844`	`847`	`serialized_response,`
`845`	`848`	`response_tx,`
`846`	`849`	`}) => {`
	`850`	`+ let network = ctxt.network;`
`847`	`851`	`self.mailbox_tx.send_response_spawner.spawn(async move {`
`848`	`852`	`Connection::send_serialized_response(`
	`853`	`+ network,`
`849`	`854`	`response_tx,`
`850`	`855`	`&serialized_response,`
`851`	`856`	`)`