X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Fchan_utils.rs;h=647fc323880dc62fddde8a94730d549f0e6d9d97;hb=bfd11282131bd642d7920bf7ad9d1e59d329ccf8;hp=2ccee7b2d521a8460b20e643355a99bff0d0632e;hpb=c7ddcd3867757c74d8a3a2997604edf52aa0a536;p=rust-lightning

diff --git a/lightning/src/ln/chan_utils.rs b/lightning/src/ln/chan_utils.rs
index 2ccee7b2..647fc323 100644
--- 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)]
@@ -843,6 +849,7 @@ impl PartialEq for CommitmentTransaction {
 	}
 }
 
+/// (C-not exported) as users never need to call this directly
 impl Writeable for Vec<HTLCOutputInCommitment> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
@@ -854,6 +861,7 @@ impl Writeable for Vec<HTLCOutputInCommitment> {
 	}
 }
 
+/// (C-not exported) as users never need to call this directly
 impl Readable for Vec<HTLCOutputInCommitment> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {