From 6644ef138d3be24558cb5a6044397bcb75a5883e Mon Sep 17 00:00:00 2001
From: =?utf8?q?Viktor=20Tigerstr=C3=B6m?=
 <11711198+ViktorTigerstrom@users.noreply.github.com>
Date: Tue, 22 Mar 2022 21:36:18 +0100
Subject: [PATCH] Add inbound htlc min/max to `ChannelDetails`

---
 fuzz/src/router.rs                 |  2 ++
 lightning/src/ln/channel.rs        | 16 +++++++++++++++-
 lightning/src/ln/channelmanager.rs |  9 +++++++++
 lightning/src/routing/router.rs    |  4 ++++
 4 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/fuzz/src/router.rs b/fuzz/src/router.rs
index bff177b1..4db6587b 100644
--- a/fuzz/src/router.rs
+++ b/fuzz/src/router.rs
@@ -227,6 +227,8 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 								is_usable: true, is_public: true,
 								balance_msat: 0,
 								outbound_capacity_msat: 0,
+								inbound_htlc_minimum_msat: None,
+								inbound_htlc_maximum_msat: None,
 							});
 						}
 						Some(&first_hops_vec[..])
diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 9ccdf816..12fd6958 100644
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -4321,11 +4321,15 @@ impl<Signer: Sign> Channel<Signer> {
 	}
 
 	/// Allowed in any state (including after shutdown)
-	#[cfg(test)]
 	pub fn get_holder_htlc_minimum_msat(&self) -> u64 {
 		self.holder_htlc_minimum_msat
 	}
 
+	/// Allowed in any state (including after shutdown), but will return none before TheirInitSent
+	pub fn get_holder_htlc_maximum_msat(&self) -> Option<u64> {
+		self.get_htlc_maximum_msat(self.holder_max_htlc_value_in_flight_msat)
+	}
+
 	/// Allowed in any state (including after shutdown)
 	pub fn get_announced_htlc_max_msat(&self) -> u64 {
 		return cmp::min(
@@ -4343,6 +4347,16 @@ impl<Signer: Sign> Channel<Signer> {
 		self.counterparty_htlc_minimum_msat
 	}
 
+	fn get_htlc_maximum_msat(&self, party_max_htlc_value_in_flight_msat: u64) -> Option<u64> {
+		self.counterparty_selected_channel_reserve_satoshis.map(|counterparty_reserve| {
+			let holder_reserve = self.holder_selected_channel_reserve_satoshis;
+			cmp::min(
+				(self.channel_value_satoshis - counterparty_reserve - holder_reserve) * 1000,
+				party_max_htlc_value_in_flight_msat
+			)
+		})
+	}
+
 	pub fn get_value_satoshis(&self) -> u64 {
 		self.channel_value_satoshis
 	}
diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 7323930f..abb20845 100644
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -1046,6 +1046,11 @@ pub struct ChannelDetails {
 	pub is_usable: bool,
 	/// True if this channel is (or will be) publicly-announced.
 	pub is_public: bool,
+	/// The smallest value HTLC (in msat) we will accept, for this channel. This field
+	/// is only `None` for `ChannelDetails` objects serialized prior to LDK 0.0.107
+	pub inbound_htlc_minimum_msat: Option<u64>,
+	/// The largest value HTLC (in msat) we currently will accept, for this channel.
+	pub inbound_htlc_maximum_msat: Option<u64>,
 }
 
 impl ChannelDetails {
@@ -1689,6 +1694,8 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 					is_funding_locked: channel.is_usable(),
 					is_usable: channel.is_live(),
 					is_public: channel.should_announce(),
+					inbound_htlc_minimum_msat: Some(channel.get_holder_htlc_minimum_msat()),
+					inbound_htlc_maximum_msat: channel.get_holder_htlc_maximum_msat()
 				});
 			}
 		}
@@ -5918,6 +5925,8 @@ impl_writeable_tlv_based!(ChannelDetails, {
 	(28, is_funding_locked, required),
 	(30, is_usable, required),
 	(32, is_public, required),
+	(33, inbound_htlc_minimum_msat, option),
+	(35, inbound_htlc_maximum_msat, option),
 });
 
 impl_writeable_tlv_based!(PhantomRouteHints, {
diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs
index 655a53c2..5afe052b 100644
--- a/lightning/src/routing/router.rs
+++ b/lightning/src/routing/router.rs
@@ -1750,6 +1750,8 @@ mod tests {
 			force_close_spend_delay: None,
 			is_outbound: true, is_funding_locked: true,
 			is_usable: true, is_public: true,
+			inbound_htlc_minimum_msat: None,
+			inbound_htlc_maximum_msat: None,
 		}
 	}
 
@@ -5475,6 +5477,8 @@ mod benches {
 			is_funding_locked: true,
 			is_usable: true,
 			is_public: true,
+			inbound_htlc_minimum_msat: None,
+			inbound_htlc_maximum_msat: None,
 		}
 	}
 
-- 
2.30.2