Fix off-by-one max witness estimate for P2WPKH StaticPaymentDescriptor

[rust-lightning] / lightning / src / sign / mod.rs

diff --git a/lightning/src/sign/mod.rs b/lightning/src/sign/mod.rs
index 04652166f05978b6dd8bb1ab0a4b4c2ed9c37d5f..9a30253049d1bf0816626377ce0c258e568db7e9 100644 (file)
--- a/lightning/src/sign/mod.rs
+++ b/lightning/src/sign/mod.rs
@@ -107,6 +107,12 @@ impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
        (12, channel_value_satoshis, required),
 });
 
+pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = 1 /* num stack items */ +
+       1 /* sig length */ +
+       73 /* sig including sighash flag */ +
+       1 /* pubkey length */ +
+       33 /* pubkey */;
+
 /// Information about a spendable output to our "payment key".
 ///
 /// See [`SpendableOutputDescriptor::StaticPaymentOutput`] for more details on how to spend this.
@@ -141,9 +147,7 @@ impl StaticPaymentOutputDescriptor {
                        1 /* num witness items */ + 1 /* sig push */ + 73 /* sig including sighash flag */ +
                                1 /* witness script push */ + witness_script_weight
                } else {
-                       // Calculated as 1 byte legnth + 73 byte signature, 1 byte empty vec push, 1 byte length plus
-                       // redeemscript push length.
-                       1 + 73 + 34
+                       P2WPKH_WITNESS_WEIGHT as usize
                }
        }
 }