f - Limit additional branching

Author: jkczyz

lightning/src/routing/scoring.rs

@@ -669,22 +669,26 @@ impl<L: Deref<Target = u64>, T: Time, U: Deref<Target = T>> DirectedChannelLiqui
 	/// Returns a penalty for routing the given HTLC `amount_msat` through the channel in this
 	/// direction.
 	fn penalty_msat(&self, amount_msat: u64, liquidity_penalty_multiplier_msat: u64) -> u64 {
+		let max_penalty_msat = liquidity_penalty_multiplier_msat.saturating_mul(2);
 		let max_liquidity_msat = self.max_liquidity_msat();
 		let min_liquidity_msat = core::cmp::min(self.min_liquidity_msat(), max_liquidity_msat);
 		if amount_msat <= min_liquidity_msat {
 			0
-		} else if amount_msat > max_liquidity_msat {
-			u64::max_value()
-		} else if amount_msat == max_liquidity_msat && max_liquidity_msat != self.capacity_msat {
-			// Avoid using the failed channel on retry.
-			u64::max_value()
+		} else if amount_msat >= max_liquidity_msat {
+			if amount_msat > max_liquidity_msat {
+				u64::max_value()
+			} else if max_liquidity_msat != self.capacity_msat {
+				// Avoid using the failed channel on retry.
+				u64::max_value()
+			} else {
+				max_penalty_msat
+			}
 		} else {
 			let numerator = (max_liquidity_msat - amount_msat).saturating_add(1);
 			let denominator = (max_liquidity_msat - min_liquidity_msat).saturating_add(1);
 			let penalty_msat = approx::negative_log10_times_1024(numerator, denominator)
 				.saturating_mul(liquidity_penalty_multiplier_msat) / 1024;
 			// Upper bound the penalty to ensure some channel is selected.
-			let max_penalty_msat = liquidity_penalty_multiplier_msat.saturating_mul(2);
 			penalty_msat.min(max_penalty_msat)
 		}
 	}