From 85b573ddad70f3c5ee36e0992d587842af507a8d Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Mon, 20 Mar 2023 23:24:56 +0000 Subject: [PATCH] Add an `optional_vec` TLV format which makes sense, unlike vec_type `vec_type` is confusing - it is happy to have a missing entry, "reading" an empty `Vec` instead, but always writes something, making a serialization round-trip different. This is a problem for writing a new `Vec` which is backwards-incompatible, but only if filled in. In that case we'd really like the same read behavior, but not write anything if the `Vec` is empty. Here we introduce such semantics via a new `optional_vec` TLV format. --- lightning/src/util/ser_macros.rs | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/lightning/src/util/ser_macros.rs b/lightning/src/util/ser_macros.rs index 59402f6a..05555407 100644 --- a/lightning/src/util/ser_macros.rs +++ b/lightning/src/util/ser_macros.rs @@ -39,6 +39,11 @@ macro_rules! _encode_tlv { field.write($stream)?; } }; + ($stream: expr, $type: expr, $field: expr, optional_vec) => { + if !$field.is_empty() { + $crate::_encode_tlv!($stream, $type, $field, vec_type); + } + }; ($stream: expr, $type: expr, $field: expr, upgradable_required) => { $crate::_encode_tlv!($stream, $type, $field, required); }; @@ -165,6 +170,11 @@ macro_rules! _get_varint_length_prefixed_tlv_length { $len.0 += field_len; } }; + ($len: expr, $type: expr, $field: expr, optional_vec) => { + if !$field.is_empty() { + $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, vec_type); + } + }; ($len: expr, $type: expr, $field: expr, (option: $trait: ident $(, $read_arg: expr)?)) => { $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, option); }; @@ -226,6 +236,9 @@ macro_rules! _check_decoded_tlv_order { ($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, vec_type) => {{ // no-op }}; + ($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, optional_vec) => {{ + // no-op + }}; ($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, upgradable_required) => {{ _check_decoded_tlv_order!($last_seen_type, $typ, $type, $field, required) }}; @@ -271,6 +284,9 @@ macro_rules! _check_missing_tlv { ($last_seen_type: expr, $type: expr, $field: ident, option) => {{ // no-op }}; + ($last_seen_type: expr, $type: expr, $field: ident, optional_vec) => {{ + // no-op + }}; ($last_seen_type: expr, $type: expr, $field: ident, upgradable_required) => {{ _check_missing_tlv!($last_seen_type, $type, $field, required) }}; @@ -308,6 +324,9 @@ macro_rules! _decode_tlv { ($reader: expr, $field: ident, option) => {{ $field = Some($crate::util::ser::Readable::read(&mut $reader)?); }}; + ($reader: expr, $field: ident, optional_vec) => {{ + $crate::_decode_tlv!($reader, $field, vec_type); + }}; // `upgradable_required` indicates we're reading a required TLV that may have been upgraded // without backwards compat. We'll error if the field is missing, and return `Ok(None)` if the // field is present but we can no longer understand it. @@ -675,6 +694,9 @@ macro_rules! _init_tlv_based_struct_field { ($field: ident, vec_type) => { $field.unwrap() }; + ($field: ident, optional_vec) => { + $field.unwrap() + }; } /// Initializes the variable we are going to read the TLV into. @@ -701,6 +723,9 @@ macro_rules! _init_tlv_field_var { ($field: ident, option) => { let mut $field = None; }; + ($field: ident, optional_vec) => { + let mut $field = Some(Vec::new()); + }; ($field: ident, (option: $trait: ident $(, $read_arg: expr)?)) => { $crate::_init_tlv_field_var!($field, option); }; @@ -733,7 +758,8 @@ macro_rules! _init_and_read_tlv_fields { /// 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 `option`, then `$field` is optional field. -/// If `$fieldty` is `vec_type`, then `$field` is a [`Vec`], which needs to have its individual elements serialized. +/// If `$fieldty` is `optional_vec`, then `$field` is a [`Vec`], which needs to have its individual elements serialized. +/// Note that for `optional_vec` no bytes are written if the vec is empty /// /// For example, /// ``` @@ -749,7 +775,7 @@ macro_rules! _init_and_read_tlv_fields { /// (0, tlv_integer, required), /// (1, tlv_default_integer, (default_value, 7)), /// (2, tlv_optional_integer, option), -/// (3, tlv_vec_type_integer, vec_type), +/// (3, tlv_vec_type_integer, optional_vec), /// }); /// ``` /// @@ -907,7 +933,7 @@ macro_rules! _impl_writeable_tlv_based_enum_common { /// ```ignore /// impl_writeable_tlv_based_enum!(EnumName, /// (0, StructVariantA) => {(0, required_variant_field, required), (1, optional_variant_field, option)}, -/// (1, StructVariantB) => {(0, variant_field_a, required), (1, variant_field_b, required), (2, variant_vec_field, vec_type)}; +/// (1, StructVariantB) => {(0, variant_field_a, required), (1, variant_field_b, required), (2, variant_vec_field, optional_vec)}; /// (2, TupleVariantA), (3, TupleVariantB), /// ); /// ``` -- 2.30.2