Add option_without_length case to TLV macros

This allows us to handle `WithoutLength` fields to prevent the duplicate
encoding of lengths in TLVs for some types that already encode length,
such as `Script` in this case.

This is needed so that we can move `shutdown_scriptpubkey` into the
TLV stream of `OpenChannel` and `AcceptChannel`.

lightning/src/util/ser.rs

@@ -29,7 +29,7 @@ use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SI
 use bitcoin::secp256k1::ecdsa;
 use bitcoin::secp256k1::schnorr;
 use bitcoin::blockdata::constants::ChainHash;
-use bitcoin::blockdata::script::Script;
+use bitcoin::blockdata::script::{Script, self};
 use bitcoin::blockdata::transaction::{OutPoint, Transaction, TxOut};
 use bitcoin::consensus;
 use bitcoin::consensus::Encodable;
@@ -657,6 +657,21 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
+impl Writeable for WithoutLength<&Script> {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+		writer.write_all(self.0.as_bytes())
+	}
+}
+
+impl Readable for WithoutLength<Script> {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+		let v: WithoutLength<Vec<u8>> = Readable::read(r)?;
+		Ok(WithoutLength(script::Builder::from(v.0).into_script()))
+	}
+}
+
 #[derive(Debug)]
 pub(crate) struct Iterable<'a, I: Iterator<Item = &'a T> + Clone, T: 'a>(pub I);
 

lightning/src/util/ser_macros.rs

@@ -60,6 +60,9 @@ macro_rules! _encode_tlv {
 		// Just a read-mapped type
 		$crate::_encode_tlv!($stream, $type, $field, option);
 	};
+	($stream: expr, $type: expr, $field: expr, option_without_length) => {
+		$crate::_encode_tlv!($stream, $type, $field.as_ref().map(|x| $crate::util::ser::WithoutLength(x)), option);
+	};
 }
 
 /// Panics if the last seen TLV type is not numerically less than the TLV type currently being checked.
@@ -233,6 +236,9 @@ macro_rules! _check_decoded_tlv_order {
 	($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, option) => {{
 		// no-op
 	}};
+	($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, option_without_length) => {{
+		// no-op
+	}};
 	($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, vec_type) => {{
 		// no-op
 	}};
@@ -284,6 +290,9 @@ macro_rules! _check_missing_tlv {
 	($last_seen_type: expr, $type: expr, $field: ident, option) => {{
 		// no-op
 	}};
+	($last_seen_type: expr, $type: expr, $field: ident, option_without_length) => {{
+		// no-op
+	}};
 	($last_seen_type: expr, $type: expr, $field: ident, optional_vec) => {{
 		// no-op
 	}};
@@ -324,6 +333,10 @@ macro_rules! _decode_tlv {
 	($reader: expr, $field: ident, option) => {{
 		$field = Some($crate::util::ser::Readable::read(&mut $reader)?);
 	}};
+	($reader: expr, $field: ident, option_without_length) => {{
+		let f: $crate::util::ser::WithoutLength<_> = $crate::util::ser::Readable::read(&mut $reader)?;
+		$field = Some(f.0);
+	}};
 	($reader: expr, $field: ident, optional_vec) => {{
 		$crate::_decode_tlv!($reader, $field, vec_type);
 	}};
@@ -679,6 +692,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
 		$field
 	};
+	($field: ident, option_without_length) => {
+		WithoutLength($field)
+	};
 	($field: ident, (option: $trait: ident $(, $read_arg: expr)?)) => {
 		$crate::_init_tlv_based_struct_field!($field, option)
 	};
@@ -723,6 +739,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
 		let mut $field = None;
 	};
+	($field: ident, option_without_length) => {
+		let mut $field = None;
+	};
 	($field: ident, optional_vec) => {
 		let mut $field = Some(Vec::new());
 	};