fix(identify): check actual port reuse instead of original intent #6096
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When PortUse::Reuse fails and falls back to ephemeral ports, detect this by comparing observed ports with listening ports rather than tracking the original PortUse intent. Fixes libp2p#5820
elenaf9
reviewed
Oct 21, 2025
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| if observed_port_matches_listening_port(observed, &self.listen_addresses) { | ||
| // If the observed port matches any of our listening ports, | ||
| // then port reuse actually worked. Use the original observed address. | ||
| self.events | ||
| .push_back(ToSwarm::NewExternalAddrCandidate(observed.clone())); |
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I know that this is existing logic, but IMO we should only emit an event here if self.external_addresses doesn't contain the address yet. Otherwise, we keep emitting events for the same addresses again and again.
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| for protocol in addr.iter() { | ||
| match protocol { | ||
| Tcp(port) | Udp(port) => return Some(port), | ||
| _ => continue, | ||
| } | ||
| } | ||
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We should return the protocol here so that below the type of protocol is also checked in the comparison. Theoretically, a port could be reachable for one protocol but not for the other.
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| #[test] | ||
| fn test_address_translation_when_port_differs() { | ||
| use libp2p_identity::Keypair; | ||
| use libp2p_swarm::behaviour::FromSwarm; | ||
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| // Create a behavior with some listening addresses | ||
| let keypair = Keypair::generate_ed25519(); | ||
| let config = Config::new("test/1.0.0".to_string(), keypair.public()); | ||
| let mut behaviour = Behaviour::new(config); | ||
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| // Add a listening address | ||
| let listen_addr: Multiaddr = "/ip4/0.0.0.0/tcp/8080".parse().unwrap(); | ||
| behaviour | ||
| .listen_addresses | ||
| .on_swarm_event(&FromSwarm::NewListenAddr( | ||
| libp2p_swarm::behaviour::NewListenAddr { | ||
| listener_id: libp2p_core::transport::ListenerId::next(), | ||
| addr: &listen_addr, | ||
| }, |
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The tests are very much appreciated, thanks!
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When PortUse::Reuse fails and falls back to ephemeral ports, detect this by comparing observed ports with listening ports rather than tracking the original PortUse intent.
Fixes #5820
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