swarm/src/connection: Extend log when exceeding streams limit (#2716)

Log peer ID and stream limit as well as reference config option when limit is
exceeded. This should help folks running into this limit debug what is going on.

swarm/CHANGELOG.md

@@ -1,3 +1,9 @@
+# 0.36.2 [unreleased]
+
+- Extend log message when exceeding inbound negotiating streams with peer ID and limit. See [PR 2716].
+
+[PR 2716]: https://github.com/libp2p/rust-libp2p/pull/2716/
+
 # 0.36.1
 
 - Limit negotiating inbound substreams per connection. See [PR 2697].

swarm/Cargo.toml

@@ -3,7 +3,7 @@ name = "libp2p-swarm"
 edition = "2021"
 rust-version = "1.56.1"
 description = "The libp2p swarm"
-version = "0.36.1"
+version = "0.36.2"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "MIT"
 repository = "https://github.com/libp2p/rust-libp2p"

swarm/src/connection.rs

@@ -35,6 +35,7 @@ pub use pool::{EstablishedConnection, PendingConnection};
 pub use substream::{Close, Substream, SubstreamEndpoint};
 
 use crate::handler::ConnectionHandler;
+use crate::IntoConnectionHandler;
 use handler_wrapper::HandlerWrapper;
 use libp2p_core::connection::ConnectedPoint;
 use libp2p_core::multiaddr::Multiaddr;
@@ -94,12 +95,16 @@ where
     /// Builds a new `Connection` from the given substream multiplexer
     /// and connection handler.
     pub fn new(
+        peer_id: PeerId,
+        endpoint: ConnectedPoint,
         muxer: StreamMuxerBox,
-        handler: THandler,
+        handler: impl IntoConnectionHandler<Handler = THandler>,
         substream_upgrade_protocol_override: Option<upgrade::Version>,
         max_negotiating_inbound_streams: usize,
     ) -> Self {
         let wrapped_handler = HandlerWrapper::new(
+            peer_id,
+            endpoint,
             handler,
             substream_upgrade_protocol_override,
             max_negotiating_inbound_streams,

swarm/src/connection/handler_wrapper.rs

@@ -23,6 +23,7 @@ use crate::handler::{
     ConnectionHandler, ConnectionHandlerEvent, ConnectionHandlerUpgrErr, KeepAlive,
 };
 use crate::upgrade::SendWrapper;
+use crate::IntoConnectionHandler;
 
 use futures::prelude::*;
 use futures::stream::FuturesUnordered;
@@ -33,6 +34,7 @@ use libp2p_core::{
     upgrade::{self, InboundUpgradeApply, OutboundUpgradeApply, UpgradeError},
     Multiaddr,
 };
+use libp2p_core::{ConnectedPoint, PeerId};
 use std::{error, fmt, pin::Pin, task::Context, task::Poll, time::Duration};
 
 /// A wrapper for an underlying [`ConnectionHandler`].
@@ -46,6 +48,7 @@ pub struct HandlerWrapper<TConnectionHandler>
 where
     TConnectionHandler: ConnectionHandler,
 {
+    remote_peer_id: PeerId,
     /// The underlying handler.
     handler: TConnectionHandler,
     /// Futures that upgrade incoming substreams.
@@ -106,12 +109,15 @@ impl<TConnectionHandler: ConnectionHandler> std::fmt::Debug for HandlerWrapper<T
 
 impl<TConnectionHandler: ConnectionHandler> HandlerWrapper<TConnectionHandler> {
     pub(crate) fn new(
-        handler: TConnectionHandler,
+        remote_peer_id: PeerId,
+        endpoint: ConnectedPoint,
+        handler: impl IntoConnectionHandler<Handler = TConnectionHandler>,
         substream_upgrade_protocol_override: Option<upgrade::Version>,
         max_negotiating_inbound_streams: usize,
     ) -> Self {
         Self {
-            handler,
+            remote_peer_id,
+            handler: handler.into_handler(&remote_peer_id, &endpoint),
             negotiating_in: Default::default(),
             negotiating_out: Default::default(),
             queued_dial_upgrades: Vec::new(),
@@ -257,8 +263,11 @@ where
             SubstreamEndpoint::Listener => {
                 if self.negotiating_in.len() == self.max_negotiating_inbound_streams {
                     log::warn!(
-                        "Incoming substream exceeding maximum number of \
-                         negotiating inbound streams. Dropping."
+                        "Incoming substream from {} exceeding maximum number \
+                         of negotiating inbound streams {} on connection. \
+                         Dropping. See PoolConfig::with_max_negotiating_inbound_streams.",
+                        self.remote_peer_id,
+                        self.max_negotiating_inbound_streams,
                     );
                     return;
                 }

swarm/src/connection/pool.rs

@@ -747,8 +747,10 @@ where
                     );
 
                     let connection = super::Connection::new(
+                        obtained_peer_id,
+                        endpoint,
                         muxer,
-                        handler.into_handler(&obtained_peer_id, &endpoint),
+                        handler,
                         self.substream_upgrade_protocol_override,
                         self.max_negotiating_inbound_streams,
                     );