Rename ChannelKeys -> Sign and generic it consistently

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

diff --git a/lightning/src/ln/chan_utils.rs b/lightning/src/ln/chan_utils.rs
index b1171f543989c8d9deb7c6d68a18fb61e5e27af5..647fc323880dc62fddde8a94730d549f0e6d9d97 100644 (file)
--- a/lightning/src/ln/chan_utils.rs
+++ b/lightning/src/ln/chan_utils.rs
@@ -8,8 +8,7 @@
 // licenses.
 
 //! Various utilities for building scripts and deriving keys related to channels. These are
-//! largely of interest for those implementing chain::keysinterface::ChannelKeys message signing
-//! by hand.
+//! largely of interest for those implementing chain::keysinterface::Sign message signing by hand.
 
 use bitcoin::blockdata::script::{Script,Builder};
 use bitcoin::blockdata::opcodes;
@@ -384,11 +383,16 @@ impl TxCreationKeys {
        }
 }
 
+/// The maximum length of a script returned by get_revokeable_redeemscript.
+// Calculated as 6 bytes of opcodes, 1 byte push plus 2 bytes for contest_delay, and two public
+// keys of 33 bytes (+ 1 push).
+pub const REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH: usize = 6 + 3 + 34*2;
+
 /// A script either spendable by the revocation
 /// key or the broadcaster_delayed_payment_key and satisfying the relative-locktime OP_CSV constrain.
 /// Encumbering a `to_holder` output on a commitment transaction or 2nd-stage HTLC transactions.
 pub fn get_revokeable_redeemscript(revocation_key: &PublicKey, contest_delay: u16, broadcaster_delayed_payment_key: &PublicKey) -> Script {
-       Builder::new().push_opcode(opcodes::all::OP_IF)
+       let res = Builder::new().push_opcode(opcodes::all::OP_IF)
                      .push_slice(&revocation_key.serialize())
                      .push_opcode(opcodes::all::OP_ELSE)
                      .push_int(contest_delay as i64)
@@ -397,7 +401,9 @@ pub fn get_revokeable_redeemscript(revocation_key: &PublicKey, contest_delay: u1
                      .push_slice(&broadcaster_delayed_payment_key.serialize())
                      .push_opcode(opcodes::all::OP_ENDIF)
                      .push_opcode(opcodes::all::OP_CHECKSIG)
-                     .into_script()
+                     .into_script();
+       debug_assert!(res.len() <= REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH);
+       res
 }
 
 #[derive(Clone, PartialEq)]