fix: allow relay to forward unlimited bytes

Allow relay to forward unlimited bytes from one peer to another by checking if `max_circuit_bytes` equals to 0 before checking if `bytes_sent` exceeds `max_circuit_bytes`.
This will make current implementation follow the spec.
May close #5170.

Pull-Request: #5244.

Author: drHuangMHT

Cargo.lock

@@ -96,7 +96,7 @@ libp2p-ping = { version = "0.44.0", path = "protocols/ping" }
 libp2p-plaintext = { version = "0.41.0", path = "transports/plaintext" }
 libp2p-pnet = { version = "0.24.0", path = "transports/pnet" }
 libp2p-quic = { version = "0.10.2", path = "transports/quic" }
-libp2p-relay = { version = "0.17.1", path = "protocols/relay" }
+libp2p-relay = { version = "0.17.2", path = "protocols/relay" }
 libp2p-rendezvous = { version = "0.14.0", path = "protocols/rendezvous" }
 libp2p-request-response = { version = "0.26.2", path = "protocols/request-response" }
 libp2p-server = { version = "0.12.7", path = "misc/server" }

Cargo.toml

@@ -1,3 +1,8 @@
+## 0.17.2
+
+- Fix support for unlimited relay connection according to spec.
+  See [PR 5244](https://github.com/libp2p/rust-libp2p/pull/5244).
+
 ## 0.17.1
 
 - Automatically register relayed addresses as external addresses.

protocols/relay/CHANGELOG.md

@@ -3,7 +3,7 @@ name = "libp2p-relay"
 edition = "2021"
 rust-version = { workspace = true }
 description = "Communications relaying for libp2p"
-version = "0.17.1"
+version = "0.17.2"
 authors = ["Parity Technologies <[email protected]>", "Max Inden <[email protected]>"]
 license = "MIT"
 repository = "https://github.com/libp2p/rust-libp2p"

protocols/relay/Cargo.toml

@@ -72,7 +72,7 @@ where
         let this = &mut *self;
 
         loop {
-            if this.bytes_sent > this.max_circuit_bytes {
+            if this.max_circuit_bytes > 0 && this.bytes_sent > this.max_circuit_bytes {
                 return Poll::Ready(Err(io::Error::new(
                     io::ErrorKind::Other,
                     "Max circuit bytes reached.",