Add Tor support for outbound connections via SOCKS #778

jharveyb · 2026-01-30T19:02:26Z

Addresses #178 . Builds on lightningdevkit/rust-lightning#4305 .

As mentioned there, I see two drawbacks with this patch as is:

We record the peer remote address as the proxy address, not the actual onionv3 of that peer:

https://github.com/lightningdevkit/rust-lightning/blob/f9ad3450b7d8b722b440f0a5e3d9be8bd7a696ae/lightning-net-tokio/src/lib.rs#L332

Which affects list_peers() output:

{
			"pubkey": {
				"pubkey": "03864ef025fde8fb587d989186ce6a4a186895ee44a926bfc370e2c366597a3f8f"
			},
			"socket_addr": {
				"address": "3.33.236.230:9735"
			},
			"is_connected": true
		},
		{
			"pubkey": {
				"pubkey": "03fe47fdfea0f25fad0013498e8d6cec348ae3d673841ec25ee94f87c21af16ed8"
			},
			"socket_addr": {
				"address": "127.0.0.1:9050"
			},
			"is_connected": true
		}

But more significantly, AFAICT affects our setup messages with our peer:

https://github.com/lightningdevkit/rust-lightning/blob/f9ad3450b7d8b722b440f0a5e3d9be8bd7a696ae/lightning/src/ln/peer_handler.rs#L1905

The filter_addresses() call here means we won't include the proxy address, but we also won't include that peer's onion address, which we may want to do?

I'm testing this actively now and haven't hit any issues yet, though I haven't had much traffic with that peer either.

ldk-reviews-bot · 2026-01-30T19:02:29Z

I've assigned @tnull as a reviewer!
I'll wait for their review and will help manage the review process.
Once they submit their review, I'll check if a second reviewer would be helpful.

tankyleo

Thanks for the PR !

tankyleo · 2026-01-30T19:56:52Z

src/connection.rs

-			.next()
-			.ok_or_else(|| {
-				log_error!(self.logger, "Failed to resolve network address {}", addr);
+		let res = if let SocketAddress::OnionV2(old_onion_addr) = addr {


nit: did you consider using a match statement here?

tankyleo · 2026-01-30T20:00:17Z

src/connection.rs

 				self.propagate_result_to_subscribers(&node_id, Err(Error::InvalidSocketAddress));
 				Error::InvalidSocketAddress
 			})?;
+			let connection_future = lightning_net_tokio::tor_connect_outbound(


Do we want to allow people to proxy the other types over tor as well ? Have to be careful with adding more settings, but I'm thinking of an analog to the always-use-proxy=true CLN setting.

Could be done in a follow-up if preferred.

Good point, that would be a useful setting...

I'm open to add that on to this PR, would need another cfg setting I suppose.

Good point, that would be a useful setting...

I'm open to add that on to this PR, would need another cfg setting I suppose.

Let's just add this as a flag in above mentioned TorConfig struct?

tankyleo · 2026-01-30T20:15:52Z

src/builder.rs

+	let connection_manager = Arc::new(ConnectionManager::new(
+		Arc::clone(&peer_manager),
+		config.tor_proxy_address.clone(),
+		ephemeral_bytes,


This will be used to derive passwords sent in plaintext to the SOCKS5 proxy, so out of caution I would have passed a seed here that is different from the seed passed to the PeerManager to derive BOLT 8 per-connection ephemeral keys.

The KeysManager entropy source is also a chacha20 so seems to me we can cheaply do another keys_manager.get_secure_random_bytes();

tankyleo · 2026-01-30T20:30:38Z

src/connection.rs

+				node_id,
+				addr.clone(),
+				proxy_addr,
+				self.tor_proxy_rng.clone(),


nit: Would have used Arc::clone(&self.tor_proxy_rng) here, same style as the peer manager above, just to make it very clear we are only creating a new pointer to the same state, and not cloning the state itself.

ldk-reviews-bot · 2026-02-02T00:00:58Z

🔔 1st Reminder

Hey @tnull! This PR has been waiting for your review.
Please take a look when you have a chance. If you're unable to review, please let us know so we can find another reviewer.

tankyleo · 2026-02-02T02:16:57Z

@jharveyb Thanks for pointing out these quirks. From my reading, we are still onside, so I would expect everything to work on on the current main branch.

For the outbound connection case, we could add an Option<SocketAddr> parameter to fn setup_outbound in lightning-net-tokio, and we would use that parameter in fn tor_connect_outbound to override the default remote_addr with the onion V3 address we are connecting to.

While we don't have native support for inbound tor connections yet, list_peers will always display some 127.0.0.1:xxxxx for those connections.

tankyleo · 2026-02-02T02:45:16Z

this is the patch I have in mind @tnull curious your thoughts.

diff --git a/lightning-net-tokio/src/lib.rs b/lightning-net-tokio/src/lib.rs
index eec0e424e..104fd8595 100644
--- a/lightning-net-tokio/src/lib.rs
+++ b/lightning-net-tokio/src/lib.rs
@@ -378,12 +378,12 @@ where
 /// futures are freed, though, because all processing futures are spawned with tokio::spawn, you do
 /// not need to poll the provided future in order to make progress.
 pub fn setup_outbound<PM: Deref + 'static + Send + Sync + Clone>(
-       peer_manager: PM, their_node_id: PublicKey, stream: StdTcpStream,
+       peer_manager: PM, their_node_id: PublicKey, stream: StdTcpStream, remote_addr_override: Option<SocketAddress>,
 ) -> impl std::future::Future<Output = ()>
 where
        PM::Target: APeerManager<Descriptor = SocketDescriptor>,
 {
-       let remote_addr = get_addr_from_stream(&stream);
+       let remote_addr = remote_addr_override.or(get_addr_from_stream(&stream));
        let (reader, mut write_receiver, read_receiver, us) = Connection::new(stream);
        #[cfg(test)]
        let last_us = Arc::clone(&us);
@@ -469,7 +469,7 @@ where
        if let Ok(Ok(stream)) =
                time::timeout(Duration::from_secs(CONNECT_OUTBOUND_TIMEOUT), connect_fut).await
        {
-               Some(setup_outbound(peer_manager, their_node_id, stream))
+               Some(setup_outbound(peer_manager, their_node_id, stream, None))
        } else {
                None
        }
@@ -488,12 +488,12 @@ where
        PM::Target: APeerManager<Descriptor = SocketDescriptor>,
 {
        let connect_fut = async {
-               tor_connect(addr, tor_proxy_addr, entropy_source).await.map(|s| s.into_std().unwrap())
+               tor_connect(addr.clone(), tor_proxy_addr, entropy_source).await.map(|s| s.into_std().unwrap())
        };
        if let Ok(Ok(stream)) =
                time::timeout(Duration::from_secs(TOR_CONNECT_OUTBOUND_TIMEOUT), connect_fut).await
        {
-               Some(setup_outbound(peer_manager, their_node_id, stream))
+               Some(setup_outbound(peer_manager, their_node_id, stream, Some(addr)))
        } else {
                None
        }
@@ -1015,7 +1015,7 @@ mod tests {
                // 127.0.0.1.
                let (conn_a, conn_b) = make_tcp_connection();

-               let fut_a = super::setup_outbound(Arc::clone(&a_manager), b_pub, conn_a);
+               let fut_a = super::setup_outbound(Arc::clone(&a_manager), b_pub, conn_a, None);
                let fut_b = super::setup_inbound(b_manager, conn_b);

                tokio::time::timeout(Duration::from_secs(10), a_connected.recv()).await.unwrap();
@@ -1085,7 +1085,7 @@ mod tests {
                // Call connection setup inside new tokio tasks.
                let manager_reference = Arc::clone(&a_manager);
                tokio::spawn(async move { super::setup_inbound(manager_reference, conn_a).await });
-               tokio::spawn(async move { super::setup_outbound(a_manager, b_pub, conn_b).await });
+               tokio::spawn(async move { super::setup_outbound(a_manager, b_pub, conn_b, None).await });
        }

        #[tokio::test(flavor = "multi_thread")]

tnull

Cool, thanks for taking a look!

Already looks pretty good, but here are a few comments after the first pass. Do you think there is a good way to add test coverage for this to CI?

tnull · 2026-02-02T12:35:06Z

src/builder.rs

+	///
+	/// [`tor_proxy_address`]: Config::tor_proxy_address
+	pub fn set_tor_proxy_address(&mut self, tor_proxy_address: core::net::SocketAddr) {
+		self.config.tor_proxy_address = Some(tor_proxy_address);


Rather than replicating the functionality, please just call through to inner as we do elsewhere in this builder. This avoids their behavior getting out-of-sync over time.

tnull · 2026-02-02T12:36:30Z

src/config.rs

+	/// **Note**: If unset, connecting to peer OnionV3 addresses will fail.
+	///
+	/// [`tor_proxy_address`]: Config::tor_proxy_address
+	pub tor_proxy_address: Option<core::net::SocketAddr>,


Hmm, I think it would be preferable to drop this field and just add a separate Option<TorConfig> or similar. The struct TorConfig would then also allow to add tor-specific settings, such as the ones mentioned below.

Also note that we'll want to expose all of the new APIs to bindings, so you'll need to make the corresponding changes in bindings/ldk_node.udl and use SocketAddress, not SocketAddr.

tnull · 2026-02-02T12:44:11Z

src/connection.rs

 				self.propagate_result_to_subscribers(&node_id, Err(Error::InvalidSocketAddress));
 				Error::InvalidSocketAddress
 			})?;
+			let connection_future = lightning_net_tokio::tor_connect_outbound(


Good point, that would be a useful setting...

I'm open to add that on to this PR, would need another cfg setting I suppose.

Let's just add this as a flag in above mentioned TorConfig struct?

tnull · 2026-02-02T13:03:35Z

this is the patch I have in mind @tnull curious your thoughts.

Hmm, could make sense, but maybe we should only expose the override field on the Tor-specific API?

tankyleo · 2026-02-02T17:26:41Z

Hmm, could make sense, but maybe we should only expose the override field on the Tor-specific API?

The general setup_outbound function currently sets the remote_addr field with get_addr_from_stream, so we have to make a modification to the general API unfortunately.

Add Tor support for outbound connections via SOCKS

1ce0c38

ldk-reviews-bot requested a review from tnull January 30, 2026 19:13

tankyleo reviewed Jan 30, 2026

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tnull reviewed Feb 2, 2026

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tankyleo mentioned this pull request Feb 2, 2026

Add remote_addr field to lightning_net_tokio::setup_outbound lightningdevkit/rust-lightning#4372

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Add Tor support for outbound connections via SOCKS #778

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Add Tor support for outbound connections via SOCKS #778

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