Correct MIN_FINAL_CLTV_EXPIRY to match our enforced requirements

[rust-lightning] / lightning / src / ln / channelmanager.rs

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 451bf8be4a1cf02a74e4daa189658e59d8e05d98..dfcb85110f193a670d25c6054f95239f2f1d4ae3 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -43,6 +43,7 @@ use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitor
 use chain::transaction::{OutPoint, TransactionData};
 // Since this struct is returned in `list_channels` methods, expose it here in case users want to
 // construct one themselves.
+use ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 pub use ln::channel::CounterpartyForwardingInfo;
 use ln::channel::{Channel, ChannelError};
 use ln::features::{InitFeatures, NodeFeatures};
@@ -196,19 +197,6 @@ pub(super) enum HTLCFailReason {
        }
 }
 
-/// payment_hash type, use to cross-lock hop
-/// (C-not exported) as we just use [u8; 32] directly
-#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
-pub struct PaymentHash(pub [u8;32]);
-/// payment_preimage type, use to route payment between hop
-/// (C-not exported) as we just use [u8; 32] directly
-#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
-pub struct PaymentPreimage(pub [u8;32]);
-/// payment_secret type, use to authenticate sender to the receiver and tie MPP HTLCs together
-/// (C-not exported) as we just use [u8; 32] directly
-#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
-pub struct PaymentSecret(pub [u8;32]);
-
 type ShutdownResult = (Option<(OutPoint, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash)>);
 
 /// Error type returned across the channel_state mutex boundary. When an Err is generated for a
@@ -575,7 +563,7 @@ pub const BREAKDOWN_TIMEOUT: u16 = 6 * 24;
 pub(crate) const MAX_LOCAL_BREAKDOWN_TIMEOUT: u16 = 2 * 6 * 24 * 7;
 
 /// The minimum number of blocks between an inbound HTLC's CLTV and the corresponding outbound
-/// HTLC's CLTV. The current default represents roughly six hours of blocks at six blocks/hour.
+/// HTLC's CLTV. The current default represents roughly seven hours of blocks at six blocks/hour.
 ///
 /// This can be increased (but not decreased) through [`ChannelConfig::cltv_expiry_delta`]
 ///
@@ -584,13 +572,16 @@ pub(crate) const MAX_LOCAL_BREAKDOWN_TIMEOUT: u16 = 2 * 6 * 24 * 7;
 // i.e. the node we forwarded the payment on to should always have enough room to reliably time out
 // the HTLC via a full update_fail_htlc/commitment_signed dance before we hit the
 // CLTV_CLAIM_BUFFER point (we static assert that it's at least 3 blocks more).
-pub const MIN_CLTV_EXPIRY_DELTA: u16 = 6 * 6;
+pub const MIN_CLTV_EXPIRY_DELTA: u16 = 6*7;
 pub(super) const CLTV_FAR_FAR_AWAY: u32 = 6 * 24 * 7; //TODO?
 
 /// Minimum CLTV difference between the current block height and received inbound payments.
 /// Invoices generated for payment to us must set their `min_final_cltv_expiry` field to at least
 /// this value.
-pub const MIN_FINAL_CLTV_EXPIRY: u32 = HTLC_FAIL_BACK_BUFFER;
+// Note that we fail if exactly HTLC_FAIL_BACK_BUFFER + 1 was used, so we need to add one for
+// any payments to succeed. Further, we don't want payments to fail if a block was found while
+// a payment was being routed, so we add an extra block to be safe.
+pub const MIN_FINAL_CLTV_EXPIRY: u32 = HTLC_FAIL_BACK_BUFFER + 3;
 
 // Check that our CLTV_EXPIRY is at least CLTV_CLAIM_BUFFER + ANTI_REORG_DELAY + LATENCY_GRACE_PERIOD_BLOCKS,
 // ie that if the next-hop peer fails the HTLC within
@@ -3467,6 +3458,10 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
        /// If you need exact expiry semantics, you should enforce them upon receipt of
        /// [`PaymentReceived`].
        ///
+       /// Pending inbound payments are stored in memory and in serialized versions of this
+       /// [`ChannelManager`]. If potentially unbounded numbers of inbound payments may exist and
+       /// space is limited, you may wish to rate-limit inbound payment creation.
+       ///
        /// May panic if `invoice_expiry_delta_secs` is greater than one year.
        ///
        /// Note that invoices generated for inbound payments should have their `min_final_cltv_expiry`