Add max path length knob to PaymentParameters.

Will be used so the outbound_payment module can calculate the maximum path
length with knowledge of any custom TLVs or payment metadata present.

diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs
index 420f6d5d8917c431707a8e11705312c9fa8568e8..4a4063f52f99e8ce89bf5e52e7e0fbf07cce2370 100644 (file)
--- a/lightning/src/routing/router.rs
+++ b/lightning/src/routing/router.rs
@@ -686,6 +686,10 @@ pub struct PaymentParameters {
        /// Defaults to [`DEFAULT_MAX_PATH_COUNT`].
        pub max_path_count: u8,
 
+       /// The maximum number of [`Path::hops`] in any returned path.
+       /// Defaults to [`MAX_PATH_LENGTH_ESTIMATE`].
+       pub max_path_length: u8,
+
        /// Selects the maximum share of a channel's total capacity which will be sent over a channel,
        /// as a power of 1/2. A higher value prefers to send the payment using more MPP parts whereas
        /// a lower value prefers to send larger MPP parts, potentially saturating channels and
@@ -732,6 +736,7 @@ impl Writeable for PaymentParameters {
                        (8, *blinded_hints, optional_vec),
                        (9, self.payee.final_cltv_expiry_delta(), option),
                        (11, self.previously_failed_blinded_path_idxs, required_vec),
+                       (13, self.max_path_length, required),
                });
                Ok(())
        }
@@ -751,6 +756,7 @@ impl ReadableArgs<u32> for PaymentParameters {
                        (8, blinded_route_hints, optional_vec),
                        (9, final_cltv_expiry_delta, (default_value, default_final_cltv_expiry_delta)),
                        (11, previously_failed_blinded_path_idxs, optional_vec),
+                       (13, max_path_length, (default_value, MAX_PATH_LENGTH_ESTIMATE)),
                });
                let blinded_route_hints = blinded_route_hints.unwrap_or(vec![]);
                let payee = if blinded_route_hints.len() != 0 {
@@ -775,6 +781,7 @@ impl ReadableArgs<u32> for PaymentParameters {
                        expiry_time,
                        previously_failed_channels: previously_failed_channels.unwrap_or(Vec::new()),
                        previously_failed_blinded_path_idxs: previously_failed_blinded_path_idxs.unwrap_or(Vec::new()),
+                       max_path_length: _init_tlv_based_struct_field!(max_path_length, (default_value, unused)),
                })
        }
 }
@@ -791,6 +798,7 @@ impl PaymentParameters {
                        expiry_time: None,
                        max_total_cltv_expiry_delta: DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA,
                        max_path_count: DEFAULT_MAX_PATH_COUNT,
+                       max_path_length: MAX_PATH_LENGTH_ESTIMATE,
                        max_channel_saturation_power_of_half: DEFAULT_MAX_CHANNEL_SATURATION_POW_HALF,
                        previously_failed_channels: Vec::new(),
                        previously_failed_blinded_path_idxs: Vec::new(),
@@ -830,6 +838,7 @@ impl PaymentParameters {
                        expiry_time: None,
                        max_total_cltv_expiry_delta: DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA,
                        max_path_count: DEFAULT_MAX_PATH_COUNT,
+                       max_path_length: MAX_PATH_LENGTH_ESTIMATE,
                        max_channel_saturation_power_of_half: DEFAULT_MAX_CHANNEL_SATURATION_POW_HALF,
                        previously_failed_channels: Vec::new(),
                        previously_failed_blinded_path_idxs: Vec::new(),