DSCP for BGP/BFD, Default TTL of 255 for BGP, Graceful config updates for DSCP/TTL in BGP [Spring Cleaning 3/N]

bfd/src/lib.rs

@@ -4,6 +4,7 @@
 
 use anyhow::Result;
 use mg_api_types::bfd::{BfdPeerState, SessionMode};
+use mg_api_types::common::headers::Dscp;
 use mg_common::thread::ManagedThread;
 use slog::{Logger, warn};
 use sm::StateMachine;
@@ -107,12 +108,14 @@ pub struct AddPeerRequest {
     pub endpoint: BfdEndpoint,
     pub egress_thread: Option<Arc<ManagedThread>>,
     pub db: rdb::Db,
+    pub dscp: Dscp,
 }
 
 /// A session holds a BFD state machine for a particular peer.
 pub struct Session {
     pub sm: StateMachine,
     pub mode: SessionMode,
+    pub dscp: Dscp,
     pub counters: Arc<SessionCounters>,
     /// Managed egress thread for UDP packet transmission. Stored here to
     /// ensure automatic cleanup on drop — the ManagedThread's Drop impl
@@ -137,6 +140,7 @@ impl Session {
         Ok(Session {
             sm,
             mode: rq.mode,
+            dscp: rq.dscp,
             counters,
             _egress_thread: rq.egress_thread,
         })
@@ -314,6 +318,7 @@ mod test {
                 endpoint: a,
                 egress_thread: None,
                 db: db.db().clone(),
+                dscp: Dscp::CS6,
             },
         )?;
         assert_eq!(daemon.peer_state(v4_addr), Some(BfdPeerState::Down));
@@ -330,6 +335,7 @@ mod test {
                 endpoint: a,
                 egress_thread: None,
                 db: db.db().clone(),
+                dscp: Dscp::CS6,
             },
         )?;
         assert_eq!(daemon.peer_state(v6_addr), Some(BfdPeerState::Down));
@@ -368,6 +374,7 @@ mod test {
                 endpoint: a,
                 egress_thread: None,
                 db: db.db().clone(),
+                dscp: Dscp::CS6,
             },
         )?;
         net.register(v4_addr2, b);
@@ -382,6 +389,7 @@ mod test {
                 endpoint: a,
                 egress_thread: None,
                 db: db.db().clone(),
+                dscp: Dscp::CS6,
             },
         )?;
         net.register(v6_addr2, b);
@@ -398,6 +406,7 @@ mod test {
                 endpoint: a,
                 egress_thread: None,
                 db: db.db().clone(),
+                dscp: Dscp::CS6,
             },
         )?;
         net.register(v4_addr1, b);
@@ -412,6 +421,7 @@ mod test {
                 endpoint: a,
                 egress_thread: None,
                 db: db.db().clone(),
+                dscp: Dscp::CS6,
             },
         )?;
         net.register(v6_addr1, b);

bgp/src/config.rs

@@ -73,6 +73,7 @@ impl From<Neighbor> for PeerConfig {
             connect_retry_jitter: _,
             src_addr: _,
             src_port: _,
+            dscp: _,
         } = parameters;
         Self {
             name,
@@ -168,6 +169,7 @@ impl PeerConfig {
             connect_retry_jitter: _,
             src_addr: _,
             src_port: _,
+            dscp: _,
         } = parameters;
         Self {
             name,

bgp/src/connection.rs

@@ -10,6 +10,7 @@ use crate::{
     session::{FsmEvent, SessionInfo},
     unnumbered::UnnumberedManager,
 };
+use mg_api_types::common::headers::Dscp;
 use slog::Logger;
 use std::{
     net::{SocketAddr, ToSocketAddrs},
@@ -57,14 +58,6 @@ pub trait BgpListener<Cnx: BgpConnection> {
         timeout: Duration,
     ) -> Result<Cnx, Error>;
 
-    /// Apply policy to an established connection. This is called by the
-    /// Dispatcher after accept() returns and session lookup is completed.
-    fn apply_policy(
-        conn: &Cnx,
-        min_ttl: Option<u8>,
-        md5_key: Option<String>,
-    ) -> Result<(), Error>;
-
     /// `SocketAddr` the listener is receiving connections on
     fn bind_addr(&self) -> SocketAddr;
 }
@@ -134,6 +127,21 @@ pub trait BgpConnection: Send + Sync + Sized {
     /// Start the receive loop for this connection. This method is idempotent.
     /// Returns Ok(()) upon successful start of recv loop, else Err.
     fn start_recv_loop(self: &Arc<Self>) -> Result<(), Error>;
+
+    /// Update a socket option on a live connection. Used to apply
+    /// configuration changes (DSCP, TTL) without resetting the session.
+    fn update_socket_option(&self, option: &SocketOption) -> Result<(), Error>;
+
+    /// Apply MD5 authentication key to a live connection.
+    /// This is a no-op on platforms that don't support MD5 BGP auth.
+    fn apply_md5(&self, key: &str) -> Result<(), Error>;
+}
+
+/// A socket option that can be updated on a live BGP connection.
+#[derive(Clone, Debug)]
+pub enum SocketOption {
+    Dscp(Dscp),
+    MinTtl(Option<std::num::NonZeroU8>),
 }
 
 pub use mg_common::thread::{ManagedThread, ThreadState};

bgp/src/connection_channel.rs

@@ -12,7 +12,7 @@ use crate::{
     clock::ConnectionClock,
     connection::{
         BgpConnection, BgpConnector, BgpListener, ConnectionDirection,
-        ConnectionId, ThreadState,
+        ConnectionId, SocketOption, ThreadState,
     },
     error::Error,
     log::{connection_log, connection_log_lite},
@@ -271,15 +271,6 @@ impl BgpListener<BgpConnectionChannel> for BgpListenerChannel {
         ))
     }
 
-    fn apply_policy(
-        _conn: &BgpConnectionChannel,
-        _min_ttl: Option<u8>,
-        _md5_key: Option<String>,
-    ) -> Result<(), Error> {
-        // Policy application is ignored for test connections
-        Ok(())
-    }
-
     fn bind_addr(&self) -> SocketAddr {
         self.bind_addr
     }
@@ -378,6 +369,19 @@ impl BgpConnection for BgpConnectionChannel {
 
         Ok(())
     }
+
+    fn update_socket_option(
+        &self,
+        _option: &SocketOption,
+    ) -> Result<(), Error> {
+        // Socket options are ignored for test connections
+        Ok(())
+    }
+
+    fn apply_md5(&self, _key: &str) -> Result<(), Error> {
+        // MD5 auth is ignored for test connections
+        Ok(())
+    }
 }
 
 impl BgpConnectionChannel {