Set channel_override_config if we are lsp client

This copies the current code from upstream to ensure the right channel
config overrides are set when ldk-node is used from the lsp client
perspective. Could not cheryy-pick this one directly as it was part of
a large upgrade commit.

Author: amackillop

src/event.rs

@@ -36,6 +36,7 @@ use lightning::impl_writeable_tlv_based_enum;
 use lightning::ln::channelmanager::PaymentId;
 use lightning::ln::types::ChannelId;
 use lightning::routing::gossip::NodeId;
+use lightning::util::config::{ChannelConfigOverrides, ChannelConfigUpdate, ChannelHandshakeConfigUpdate};
 use lightning::util::errors::APIError;
 use lightning::util::ser::{Readable, ReadableArgs, Writeable, Writer};
 
@@ -1168,19 +1169,44 @@ where
 
 				let user_channel_id: u128 = rand::thread_rng().gen::<u128>();
 				let allow_0conf = self.config.trusted_peers_0conf.contains(&counterparty_node_id);
+				let mut channel_override_config = None;
+				if let Some((lsp_node_id, _)) = self
+					.liquidity_source
+					.as_ref()
+					.and_then(|ls| ls.as_ref().get_lsps2_lsp_details())
+				{
+					if lsp_node_id == counterparty_node_id {
+						// When we're an LSPS2 client, allow claiming underpaying HTLCs as the LSP will skim off some fee. We'll
+						// check that they don't take too much before claiming.
+						//
+						// We also set maximum allowed inbound HTLC value in flight
+						// to 100%. We should eventually be able to set this on a per-channel basis, but for
+						// now we just bump the default for all channels.
+						channel_override_config = Some(ChannelConfigOverrides {
+							handshake_overrides: Some(ChannelHandshakeConfigUpdate {
+								max_inbound_htlc_value_in_flight_percent_of_channel: Some(100),
+								..Default::default()
+							}),
+							update_overrides: Some(ChannelConfigUpdate {
+								accept_underpaying_htlcs: Some(true),
+								..Default::default()
+							}),
+						});
+					}
+				}
 				let res = if allow_0conf {
 					self.channel_manager.accept_inbound_channel_from_trusted_peer_0conf(
 						&temporary_channel_id,
 						&counterparty_node_id,
 						user_channel_id,
-						None,
+						channel_override_config,
 					)
 				} else {
 					self.channel_manager.accept_inbound_channel(
 						&temporary_channel_id,
 						&counterparty_node_id,
 						user_channel_id,
-						None,
+						channel_override_config,
 					)
 				};