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util: add default_value_vec for defaults without LengthReadable #4507

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util: add default_value_vec for defaults without LengthReadable #4507

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91 changes: 90 additions & 1 deletion lightning/src/util/ser_macros.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,9 @@ macro_rules! _encode_tlv {
($stream: expr, $type: expr, $field: expr, (default_value, $default: expr) $(, $self: ident)?) => {
$crate::_encode_tlv!($stream, $type, $field, required)
};
($stream: expr, $type: expr, $field: expr, (default_value_vec, $default: expr) $(, $self: ident)?) => {
$crate::_encode_tlv!($stream, $type, $field, required_vec)
};
($stream: expr, $type: expr, $field: expr, (static_value, $value: expr) $(, $self: ident)?) => {
let _ = &$field; // Ensure we "use" the $field
};
Expand Down Expand Up @@ -200,6 +203,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
($len: expr, $type: expr, $field: expr, (default_value, $default: expr) $(, $self: ident)?) => {
$crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required)
};
($len: expr, $type: expr, $field: expr, (default_value_vec, $default: expr) $(, $self: ident)?) => {
$crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required_vec)
};
($len: expr, $type: expr, $field: expr, (static_value, $value: expr) $(, $self: ident)?) => {};
($len: expr, $type: expr, $field: expr, required $(, $self: ident)?) => {
BigSize($type).write(&mut $len).expect("No in-memory data may fail to serialize");
Expand Down Expand Up @@ -301,6 +307,15 @@ macro_rules! _check_decoded_tlv_order {
$field = $default.into();
}
}};
($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, (default_value_vec, $default: expr)) => {{
// Note that $type may be 0 making the second comparison always false
#[allow(unused_comparisons)]
let invalid_order =
($last_seen_type.is_none() || $last_seen_type.unwrap() < $type) && $typ.0 > $type;
if invalid_order {
$field = Some($default);
}
}};
($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, (static_value, $value: expr)) => {};
($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, required) => {{
// Note that $type may be 0 making the second comparison always false
Expand Down Expand Up @@ -372,6 +387,14 @@ macro_rules! _check_missing_tlv {
$field = $default.into();
}
}};
($last_seen_type: expr, $type: expr, $field: ident, (default_value_vec, $default: expr)) => {{
// Note that $type may be 0 making the second comparison always false
#[allow(unused_comparisons)]
let missing_req_type = $last_seen_type.is_none() || $last_seen_type.unwrap() < $type;
if missing_req_type {
$field = Some($default);
}
}};
($last_seen_type: expr, $type: expr, $field: expr, (static_value, $value: expr)) => {
$field = $value;
};
Expand Down Expand Up @@ -440,6 +463,10 @@ macro_rules! _decode_tlv {
($outer_reader: expr, $reader: expr, $field: ident, (default_value, $default: expr)) => {{
$crate::_decode_tlv!($outer_reader, $reader, $field, required)
}};
($outer_reader: expr, $reader: expr, $field: ident, (default_value_vec, $default: expr)) => {{
let f: $crate::util::ser::WithoutLength<Vec<_>> = $crate::util::ser::LengthReadable::read_from_fixed_length_buffer(&mut $reader)?;
$field = Some(f.0);
}};
($outer_reader: expr, $reader: expr, $field: ident, (static_value, $value: expr)) => {{
}};
($outer_reader: expr, $reader: expr, $field: ident, required) => {{
Expand Down Expand Up @@ -854,6 +881,9 @@ macro_rules! _init_tlv_based_struct_field {
($field: ident, (default_value, $default: expr)) => {
$field.0.unwrap()
};
($field: ident, (default_value_vec, $default: expr)) => {
$field.unwrap()
};
($field: ident, (static_value, $value: expr)) => {
$field
};
Expand Down Expand Up @@ -905,6 +935,9 @@ macro_rules! _init_tlv_field_var {
($field: ident, (default_value, $default: expr)) => {
let mut $field = $crate::util::ser::RequiredWrapper(None);
};
($field: ident, (default_value_vec, $default: expr)) => {
let mut $field: Option<Vec<_>> = None;
};
($field: ident, (static_value, $value: expr)) => {
let $field;
};
Expand Down Expand Up @@ -1007,6 +1040,9 @@ macro_rules! _decode_and_build {
///
/// If `$fieldty` is `required`, then `$field` is a required field that is not an [`Option`] nor a [`Vec`].
/// If `$fieldty` is `(default_value, $default)`, then `$field` will be set to `$default` if not present.
/// If `$fieldty` is `(default_value_vec, $default)`, then `$field` is a [`Vec`] which will be set to `$default`
/// if not present. Elements are serialized individually without a count prefix (like `required_vec`).
/// The TLV is always written, even if the vec is empty (matching `default_value` behavior).
/// If `$fieldty` is `(static_value, $static)`, then `$field` will be set to `$static`.
/// If `$fieldty` is `option`, then `$field` is optional field.
/// If `$fieldty` is `upgradable_option`, then `$field` is optional and read via [`MaybeReadable`].
Expand All @@ -1019,7 +1055,7 @@ macro_rules! _decode_and_build {
/// `Some`. When reading, an optional field of type `$ty` is read, and after all TLV fields are
/// read, the `$read` closure is called with the `Option<&$ty>` value. The `$read` closure should
/// return a `Result<(), DecodeError>`. Legacy field values can be used in later
/// `default_value` or `static_value` fields by referring to the value by name.
/// `default_value`, `default_value_vec`, or `static_value` fields by referring to the value by name.
/// If `$fieldty` is `(custom, $ty, $read, $write)` then, when writing, the same behavior as
/// `legacy`, above is used. When reading, if a TLV is present, it is read as `$ty` and the
/// `$read` method is called with `Some(decoded_$ty_object)`. If no TLV is present, the field
Expand Down Expand Up @@ -1956,6 +1992,59 @@ mod tests {
assert_eq!(read, ExpandedField { new_field: (42, 0) });
}

#[derive(Debug, PartialEq, Eq)]
struct DefaultValueVecStruct {
items: Vec<u32>,
}
impl_writeable_tlv_based!(DefaultValueVecStruct, {
(1, items, (default_value_vec, vec![4, 5, 6])),
});

#[test]
fn test_default_value_vec() {
// Non-empty vec round-trips correctly.
let instance = DefaultValueVecStruct { items: vec![1, 2, 3] };
let encoded = instance.encode();
let decoded: DefaultValueVecStruct = Readable::read(&mut &encoded[..]).unwrap();
assert_eq!(decoded, instance);

// Empty TLV stream falls back to the default.
let empty_encoded = <Vec<u8>>::from_hex("00").unwrap(); // zero-length TLV stream
let decoded: DefaultValueVecStruct = Readable::read(&mut &empty_encoded[..]).unwrap();
assert_eq!(decoded, DefaultValueVecStruct { items: vec![4, 5, 6] });

// Empty vec round-trips to empty vec (TLV is always written).
let empty_vec = DefaultValueVecStruct { items: vec![] };
let encoded = empty_vec.encode();
let decoded: DefaultValueVecStruct = Readable::read(&mut &encoded[..]).unwrap();
assert_eq!(decoded, DefaultValueVecStruct { items: vec![] });
}

#[derive(Debug, PartialEq, Eq)]
struct LegacyToVecStruct {
new_items: Vec<u32>,
}
impl_writeable_tlv_based!(LegacyToVecStruct, {
(0, old_item, (legacy, u32, |_| Ok(()),
|us: &LegacyToVecStruct| us.new_items.first().copied())),
(1, new_items, (default_value_vec,
old_item.map(|v| vec![v]).unwrap_or_default())),
});

#[test]
fn test_default_value_vec_with_legacy_fallback() {
// New format: round-trips via the new TLV.
let instance = LegacyToVecStruct { new_items: vec![10, 20, 30] };
let encoded = instance.encode();
let decoded: LegacyToVecStruct = Readable::read(&mut &encoded[..]).unwrap();
assert_eq!(decoded, instance);

// Old format: only the legacy type-0 field is present, falls back via default expression.
let old_encoded = <Vec<u8>>::from_hex("0600040000002a").unwrap(); // TLV len 6, type 0, len 4, value 42u32
let decoded: LegacyToVecStruct = Readable::read(&mut &old_encoded[..]).unwrap();
assert_eq!(decoded, LegacyToVecStruct { new_items: vec![42] });
}

#[test]
fn required_vec_with_encoding() {
// Ensure that serializing a required vec with a specified encoding will survive a ser round
Expand Down
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