Merge pull request #1823 from mariocynicys/expose-tlv-macros2
[rust-lightning] / lightning / src / util / ser_macros.rs
index d37a841eaff31945ecc2af27d624ca8570552006..d137b0f677bcda557276701d8f7380eab9eb17cb 100644 (file)
@@ -7,9 +7,19 @@
 // You may not use this file except in accordance with one or both of these
 // licenses.
 
-macro_rules! encode_tlv {
+//! Some macros that implement [`Readable`]/[`Writeable`] traits for lightning messages.
+//! They also handle serialization and deserialization of TLVs.
+//!
+//! [`Readable`]: crate::util::ser::Readable
+//! [`Writeable`]: crate::util::ser::Writeable
+
+/// Implements serialization for a single TLV record.
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _encode_tlv {
        ($stream: expr, $type: expr, $field: expr, (default_value, $default: expr)) => {
-               encode_tlv!($stream, $type, $field, required)
+               $crate::_encode_tlv!($stream, $type, $field, required)
        };
        ($stream: expr, $type: expr, $field: expr, (static_value, $value: expr)) => {
                let _ = &$field; // Ensure we "use" the $field
@@ -20,7 +30,7 @@ macro_rules! encode_tlv {
                $field.write($stream)?;
        };
        ($stream: expr, $type: expr, $field: expr, vec_type) => {
-               encode_tlv!($stream, $type, $crate::util::ser::WithoutLength(&$field), required);
+               $crate::_encode_tlv!($stream, $type, $crate::util::ser::WithoutLength(&$field), required);
        };
        ($stream: expr, $optional_type: expr, $optional_field: expr, option) => {
                if let Some(ref field) = $optional_field {
@@ -30,24 +40,67 @@ macro_rules! encode_tlv {
                }
        };
        ($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
-               encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
+               $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
        };
        ($stream: expr, $type: expr, $field: expr, (option, encoding: $fieldty: ty)) => {
-               encode_tlv!($stream, $type, $field, option);
+               $crate::_encode_tlv!($stream, $type, $field, option);
        };
 }
 
-
-macro_rules! check_encoded_tlv_order {
+/// Panics if the last seen TLV type is not numerically less than the TLV type currently being checked.
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _check_encoded_tlv_order {
        ($last_type: expr, $type: expr, (static_value, $value: expr)) => { };
        ($last_type: expr, $type: expr, $fieldty: tt) => {
                if let Some(t) = $last_type {
-                       debug_assert!(t <= $type);
+                       #[allow(unused_comparisons)] // Note that $type may be 0 making the following comparison always false
+                       (debug_assert!(t < $type))
                }
                $last_type = Some($type);
        };
 }
 
+/// Implements the TLVs serialization part in a [`Writeable`] implementation of a struct.
+///
+/// This should be called inside a method which returns `Result<_, `[`io::Error`]`>`, such as
+/// [`Writeable::write`]. It will only return an `Err` if the stream `Err`s or [`Writeable::write`]
+/// on one of the fields `Err`s.
+///
+/// `$stream` must be a `&mut `[`Writer`] which will receive the bytes for each TLV in the stream.
+///
+/// Fields MUST be sorted in `$type`-order.
+///
+/// Note that the lightning TLV requirements require that a single type not appear more than once,
+/// that TLVs are sorted in type-ascending order, and that any even types be understood by the
+/// decoder.
+///
+/// Any `option` fields which have a value of `None` will not be serialized at all.
+///
+/// For example,
+/// ```
+/// # use lightning::encode_tlv_stream;
+/// # fn write<W: lightning::util::ser::Writer> (stream: &mut W) -> Result<(), lightning::io::Error> {
+/// let mut required_value = 0u64;
+/// let mut optional_value: Option<u64> = None;
+/// encode_tlv_stream!(stream, {
+///     (0, required_value, required),
+///     (1, Some(42u64), option),
+///     (2, optional_value, option),
+/// });
+/// // At this point `required_value` has been written as a TLV of type 0, `42u64` has been written
+/// // as a TLV of type 1 (indicating the reader may ignore it if it is not understood), and *no*
+/// // TLV is written with type 2.
+/// # Ok(())
+/// # }
+/// ```
+///
+/// [`Writeable`]: crate::util::ser::Writeable
+/// [`io::Error`]: crate::io::Error
+/// [`Writeable::write`]: crate::util::ser::Writeable::write
+/// [`Writer`]: crate::util::ser::Writer
+#[macro_export]
 macro_rules! encode_tlv_stream {
        ($stream: expr, {$(($type: expr, $field: expr, $fieldty: tt)),* $(,)*}) => { {
                #[allow(unused_imports)]
@@ -55,10 +108,11 @@ macro_rules! encode_tlv_stream {
                        ln::msgs::DecodeError,
                        util::ser,
                        util::ser::BigSize,
+                       util::ser::Writeable,
                };
 
                $(
-                       encode_tlv!($stream, $type, $field, $fieldty);
+                       $crate::_encode_tlv!($stream, $type, $field, $fieldty);
                )*
 
                #[allow(unused_mut, unused_variables, unused_assignments)]
@@ -66,15 +120,21 @@ macro_rules! encode_tlv_stream {
                {
                        let mut last_seen: Option<u64> = None;
                        $(
-                               check_encoded_tlv_order!(last_seen, $type, $fieldty);
+                               $crate::_check_encoded_tlv_order!(last_seen, $type, $fieldty);
                        )*
                }
        } }
 }
 
-macro_rules! get_varint_length_prefixed_tlv_length {
+/// Adds the length of the serialized field to a [`LengthCalculatingWriter`].
+/// This is exported for use by other exported macros, do not use directly.
+///
+/// [`LengthCalculatingWriter`]: crate::util::ser::LengthCalculatingWriter
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _get_varint_length_prefixed_tlv_length {
        ($len: expr, $type: expr, $field: expr, (default_value, $default: expr)) => {
-               get_varint_length_prefixed_tlv_length!($len, $type, $field, required)
+               $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required)
        };
        ($len: expr, $type: expr, $field: expr, (static_value, $value: expr)) => {
        };
@@ -85,7 +145,7 @@ macro_rules! get_varint_length_prefixed_tlv_length {
                $len.0 += field_len;
        };
        ($len: expr, $type: expr, $field: expr, vec_type) => {
-               get_varint_length_prefixed_tlv_length!($len, $type, $crate::util::ser::WithoutLength(&$field), required);
+               $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $crate::util::ser::WithoutLength(&$field), required);
        };
        ($len: expr, $optional_type: expr, $optional_field: expr, option) => {
                if let Some(ref field) = $optional_field {
@@ -97,25 +157,33 @@ macro_rules! get_varint_length_prefixed_tlv_length {
        };
 }
 
-macro_rules! encode_varint_length_prefixed_tlv {
+/// See the documentation of [`write_tlv_fields`].
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _encode_varint_length_prefixed_tlv {
        ($stream: expr, {$(($type: expr, $field: expr, $fieldty: tt)),*}) => { {
                use $crate::util::ser::BigSize;
                let len = {
                        #[allow(unused_mut)]
                        let mut len = $crate::util::ser::LengthCalculatingWriter(0);
                        $(
-                               get_varint_length_prefixed_tlv_length!(len, $type, $field, $fieldty);
+                               $crate::_get_varint_length_prefixed_tlv_length!(len, $type, $field, $fieldty);
                        )*
                        len.0
                };
                BigSize(len as u64).write($stream)?;
-               encode_tlv_stream!($stream, { $(($type, $field, $fieldty)),* });
+               $crate::encode_tlv_stream!($stream, { $(($type, $field, $fieldty)),* });
        } }
 }
 
-macro_rules! check_decoded_tlv_order {
+/// Errors if there are missing required TLV types between the last seen type and the type currently being processed.
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _check_decoded_tlv_order {
        ($last_seen_type: expr, $typ: expr, $type: expr, $field: ident, (default_value, $default: expr)) => {{
-               #[allow(unused_comparisons)] // Note that $type may be 0 making the second comparison always true
+               #[allow(unused_comparisons)] // Note that $type may be 0 making the second comparison always false
                let invalid_order = ($last_seen_type.is_none() || $last_seen_type.unwrap() < $type) && $typ.0 > $type;
                if invalid_order {
                        $field = $default.into();
@@ -124,7 +192,7 @@ macro_rules! check_decoded_tlv_order {
        ($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) => {{
-               #[allow(unused_comparisons)] // Note that $type may be 0 making the second comparison always true
+               #[allow(unused_comparisons)] // Note that $type may be 0 making the second comparison always false
                let invalid_order = ($last_seen_type.is_none() || $last_seen_type.unwrap() < $type) && $typ.0 > $type;
                if invalid_order {
                        return Err(DecodeError::InvalidValue);
@@ -147,9 +215,13 @@ macro_rules! check_decoded_tlv_order {
        }};
 }
 
-macro_rules! check_missing_tlv {
+/// Errors if there are missing required TLV types after the last seen type.
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _check_missing_tlv {
        ($last_seen_type: expr, $type: expr, $field: ident, (default_value, $default: expr)) => {{
-               #[allow(unused_comparisons)] // Note that $type may be 0 making the second comparison always true
+               #[allow(unused_comparisons)] // Note that $type may be 0 making the second comparison always false
                let missing_req_type = $last_seen_type.is_none() || $last_seen_type.unwrap() < $type;
                if missing_req_type {
                        $field = $default.into();
@@ -159,7 +231,7 @@ macro_rules! check_missing_tlv {
                $field = $value;
        };
        ($last_seen_type: expr, $type: expr, $field: ident, required) => {{
-               #[allow(unused_comparisons)] // Note that $type may be 0 making the second comparison always true
+               #[allow(unused_comparisons)] // Note that $type may be 0 making the second comparison always false
                let missing_req_type = $last_seen_type.is_none() || $last_seen_type.unwrap() < $type;
                if missing_req_type {
                        return Err(DecodeError::InvalidValue);
@@ -182,9 +254,13 @@ macro_rules! check_missing_tlv {
        }};
 }
 
-macro_rules! decode_tlv {
+/// Implements deserialization for a single TLV record.
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _decode_tlv {
        ($reader: expr, $field: ident, (default_value, $default: expr)) => {{
-               decode_tlv!($reader, $field, required)
+               $crate::_decode_tlv!($reader, $field, required)
        }};
        ($reader: expr, $field: ident, (static_value, $value: expr)) => {{
        }};
@@ -211,33 +287,89 @@ macro_rules! decode_tlv {
                };
        }};
        ($reader: expr, $field: ident, (option, encoding: $fieldty: ty)) => {{
-               decode_tlv!($reader, $field, option);
+               $crate::_decode_tlv!($reader, $field, option);
        }};
 }
 
+/// Checks if `$val` matches `$type`.
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
 macro_rules! _decode_tlv_stream_match_check {
        ($val: ident, $type: expr, (static_value, $value: expr)) => { false };
        ($val: ident, $type: expr, $fieldty: tt) => { $val == $type }
 }
 
-// `$decode_custom_tlv` is a closure that may be optionally provided to handle custom message types.
-// If it is provided, it will be called with the custom type and the `FixedLengthReader` containing
-// the message contents. It should return `Ok(true)` if the custom message is successfully parsed,
-// `Ok(false)` if the message type is unknown, and `Err(DecodeError)` if parsing fails.
+/// Implements the TLVs deserialization part in a [`Readable`] implementation of a struct.
+///
+/// This should be called inside a method which returns `Result<_, `[`DecodeError`]`>`, such as
+/// [`Readable::read`]. It will either return an `Err` or ensure all `required` fields have been
+/// read and optionally read `optional` fields.
+///
+/// `$stream` must be a [`Read`] and will be fully consumed, reading until no more bytes remain
+/// (i.e. it returns [`DecodeError::ShortRead`]).
+///
+/// Fields MUST be sorted in `$type`-order.
+///
+/// Note that the lightning TLV requirements require that a single type not appear more than once,
+/// that TLVs are sorted in type-ascending order, and that any even types be understood by the
+/// decoder.
+///
+/// For example,
+/// ```
+/// # use lightning::decode_tlv_stream;
+/// # fn read<R: lightning::io::Read> (stream: R) -> Result<(), lightning::ln::msgs::DecodeError> {
+/// let mut required_value = 0u64;
+/// let mut optional_value: Option<u64> = None;
+/// decode_tlv_stream!(stream, {
+///     (0, required_value, required),
+///     (2, optional_value, option),
+/// });
+/// // At this point, `required_value` has been overwritten with the TLV with type 0.
+/// // `optional_value` may have been overwritten, setting it to `Some` if a TLV with type 2 was
+/// // present.
+/// # Ok(())
+/// # }
+/// ```
+///
+/// [`Readable`]: crate::util::ser::Readable
+/// [`DecodeError`]: crate::ln::msgs::DecodeError
+/// [`Readable::read`]: crate::util::ser::Readable::read
+/// [`Read`]: crate::io::Read
+/// [`DecodeError::ShortRead`]: crate::ln::msgs::DecodeError::ShortRead
+#[macro_export]
 macro_rules! decode_tlv_stream {
+       ($stream: expr, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}) => {
+               let rewind = |_, _| { unreachable!() };
+               $crate::_decode_tlv_stream_range!($stream, .., rewind, {$(($type, $field, $fieldty)),*});
+       }
+}
+
+/// Similar to [`decode_tlv_stream`] with a custom TLV decoding capabilities.
+///
+/// `$decode_custom_tlv` is a closure that may be optionally provided to handle custom message types.
+/// If it is provided, it will be called with the custom type and the [`FixedLengthReader`] containing
+/// the message contents. It should return `Ok(true)` if the custom message is successfully parsed,
+/// `Ok(false)` if the message type is unknown, and `Err(`[`DecodeError`]`)` if parsing fails.
+///
+/// [`FixedLengthReader`]: crate::util::ser::FixedLengthReader
+/// [`DecodeError`]: crate::ln::msgs::DecodeError
+macro_rules! decode_tlv_stream_with_custom_tlv_decode {
        ($stream: expr, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}
         $(, $decode_custom_tlv: expr)?) => { {
                let rewind = |_, _| { unreachable!() };
-               use core::ops::RangeBounds;
-               decode_tlv_stream_range!(
+               _decode_tlv_stream_range!(
                        $stream, .., rewind, {$(($type, $field, $fieldty)),*} $(, $decode_custom_tlv)?
                );
        } }
 }
 
-macro_rules! decode_tlv_stream_range {
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _decode_tlv_stream_range {
        ($stream: expr, $range: expr, $rewind: ident, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}
         $(, $decode_custom_tlv: expr)?) => { {
+               use core::ops::RangeBounds;
                use $crate::ln::msgs::DecodeError;
                let mut last_seen_type: Option<u64> = None;
                let mut stream_ref = $stream;
@@ -249,7 +381,7 @@ macro_rules! decode_tlv_stream_range {
                                // We track whether any bytes were read during the consensus_decode call to
                                // determine whether we should break or return ShortRead if we get an
                                // UnexpectedEof. This should in every case be largely cosmetic, but its nice to
-                               // pass the TLV test vectors exactly, which requre this distinction.
+                               // pass the TLV test vectors exactly, which require this distinction.
                                let mut tracking_reader = ser::ReadTrackingReader::new(&mut stream_ref);
                                match <$crate::util::ser::BigSize as $crate::util::ser::Readable>::read(&mut tracking_reader) {
                                        Err(DecodeError::ShortRead) => {
@@ -279,9 +411,9 @@ macro_rules! decode_tlv_stream_range {
                                },
                                _ => {},
                        }
-                       // As we read types, make sure we hit every required type:
+                       // As we read types, make sure we hit every required type between `last_seen_type` and `typ`:
                        $({
-                               check_decoded_tlv_order!(last_seen_type, typ, $type, $field, $fieldty);
+                               $crate::_check_decoded_tlv_order!(last_seen_type, typ, $type, $field, $fieldty);
                        })*
                        last_seen_type = Some(typ.0);
 
@@ -289,8 +421,8 @@ macro_rules! decode_tlv_stream_range {
                        let length: ser::BigSize = $crate::util::ser::Readable::read(&mut stream_ref)?;
                        let mut s = ser::FixedLengthReader::new(&mut stream_ref, length.0);
                        match typ.0 {
-                               $(_t if _decode_tlv_stream_match_check!(_t, $type, $fieldty) => {
-                                       decode_tlv!(s, $field, $fieldty);
+                               $(_t if $crate::_decode_tlv_stream_match_check!(_t, $type, $fieldty) => {
+                                       $crate::_decode_tlv!(s, $field, $fieldty);
                                        if s.bytes_remain() {
                                                s.eat_remaining()?; // Return ShortRead if there's actually not enough bytes
                                                return Err(DecodeError::InvalidValue);
@@ -314,7 +446,7 @@ macro_rules! decode_tlv_stream_range {
                }
                // Make sure we got to each required type after we've read every TLV:
                $({
-                       check_missing_tlv!(last_seen_type, $type, $field, $fieldty);
+                       $crate::_check_missing_tlv!(last_seen_type, $type, $field, $fieldty);
                })*
        } }
 }
@@ -331,7 +463,7 @@ macro_rules! impl_writeable_msg {
                impl $crate::util::ser::Readable for $st {
                        fn read<R: $crate::io::Read>(r: &mut R) -> Result<Self, $crate::ln::msgs::DecodeError> {
                                $(let $field = $crate::util::ser::Readable::read(r)?;)*
-                               $(init_tlv_field_var!($tlvfield, $fieldty);)*
+                               $(_init_tlv_field_var!($tlvfield, $fieldty);)*
                                decode_tlv_stream!(r, {$(($type, $tlvfield, $fieldty)),*});
                                Ok(Self {
                                        $($field),*,
@@ -375,12 +507,14 @@ macro_rules! impl_writeable {
 ///               object.
 /// $min_version_that_can_read_this is the minimum reader version which can understand this
 ///                                 serialized object. Previous versions will simply err with a
-///                                 DecodeError::UnknownVersion.
+///                                 [`DecodeError::UnknownVersion`].
 ///
-/// Updates to either $this_version or $min_version_that_can_read_this should be included in
+/// Updates to either `$this_version` or `$min_version_that_can_read_this` should be included in
 /// release notes.
 ///
 /// Both version fields can be specific to this type of object.
+///
+/// [`DecodeError::UnknownVersion`]: crate::ln::msgs::DecodeError::UnknownVersion
 macro_rules! write_ver_prefix {
        ($stream: expr, $this_version: expr, $min_version_that_can_read_this: expr) => {
                $stream.write_all(&[$this_version; 1])?;
@@ -388,23 +522,26 @@ macro_rules! write_ver_prefix {
        }
 }
 
-/// Writes out a suffix to an object which contains potentially backwards-compatible, optional
-/// fields which old nodes can happily ignore.
+/// Writes out a suffix to an object as a length-prefixed TLV stream which contains potentially
+/// backwards-compatible, optional fields which old nodes can happily ignore.
 ///
 /// It is written out in TLV format and, as with all TLV fields, unknown even fields cause a
-/// DecodeError::UnknownRequiredFeature error, with unknown odd fields ignored.
+/// [`DecodeError::UnknownRequiredFeature`] error, with unknown odd fields ignored.
 ///
 /// This is the preferred method of adding new fields that old nodes can ignore and still function
 /// correctly.
+///
+/// [`DecodeError::UnknownRequiredFeature`]: crate::ln::msgs::DecodeError::UnknownRequiredFeature
+#[macro_export]
 macro_rules! write_tlv_fields {
        ($stream: expr, {$(($type: expr, $field: expr, $fieldty: tt)),* $(,)*}) => {
-               encode_varint_length_prefixed_tlv!($stream, {$(($type, $field, $fieldty)),*})
+               $crate::_encode_varint_length_prefixed_tlv!($stream, {$(($type, $field, $fieldty)),*})
        }
 }
 
-/// Reads a prefix added by write_ver_prefix!(), above. Takes the current version of the
+/// Reads a prefix added by [`write_ver_prefix`], above. Takes the current version of the
 /// serialization logic for this object. This is compared against the
-/// $min_version_that_can_read_this added by write_ver_prefix!().
+/// `$min_version_that_can_read_this` added by [`write_ver_prefix`].
 macro_rules! read_ver_prefix {
        ($stream: expr, $this_version: expr) => { {
                let ver: u8 = Readable::read($stream)?;
@@ -416,17 +553,24 @@ macro_rules! read_ver_prefix {
        } }
 }
 
-/// Reads a suffix added by write_tlv_fields.
+/// Reads a suffix added by [`write_tlv_fields`].
+///
+/// [`write_tlv_fields`]: crate::write_tlv_fields
+#[macro_export]
 macro_rules! read_tlv_fields {
        ($stream: expr, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}) => { {
                let tlv_len: $crate::util::ser::BigSize = $crate::util::ser::Readable::read($stream)?;
                let mut rd = $crate::util::ser::FixedLengthReader::new($stream, tlv_len.0);
-               decode_tlv_stream!(&mut rd, {$(($type, $field, $fieldty)),*});
+               $crate::decode_tlv_stream!(&mut rd, {$(($type, $field, $fieldty)),*});
                rd.eat_remaining().map_err(|_| $crate::ln::msgs::DecodeError::ShortRead)?;
        } }
 }
 
-macro_rules! init_tlv_based_struct_field {
+/// Initializes the struct fields.
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _init_tlv_based_struct_field {
        ($field: ident, (default_value, $default: expr)) => {
                $field.0.unwrap()
        };
@@ -444,7 +588,11 @@ macro_rules! init_tlv_based_struct_field {
        };
 }
 
-macro_rules! init_tlv_field_var {
+/// Initializes the variable we are going to read the TLV into.
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _init_tlv_field_var {
        ($field: ident, (default_value, $default: expr)) => {
                let mut $field = $crate::util::ser::OptionDeserWrapper(None);
        };
@@ -462,28 +610,54 @@ macro_rules! init_tlv_field_var {
        };
 }
 
-macro_rules! init_and_read_tlv_fields {
+/// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].
+/// This is exported for use by other exported macros, do not use directly.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _init_and_read_tlv_fields {
        ($reader: ident, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}) => {
                $(
-                       init_tlv_field_var!($field, $fieldty);
+                       $crate::_init_tlv_field_var!($field, $fieldty);
                )*
 
-               read_tlv_fields!($reader, {
+               $crate::read_tlv_fields!($reader, {
                        $(($type, $field, $fieldty)),*
                });
        }
 }
 
-/// Implements Readable/Writeable for a struct storing it as a set of TLVs
-/// If $fieldty is `required`, then $field is a required field that is not an Option nor a Vec.
-/// If $fieldty is `option`, then $field is optional field.
-/// if $fieldty is `vec_type`, then $field is a Vec, which needs to have its individual elements
-/// serialized.
+/// Implements [`Readable`]/[`Writeable`] for a struct storing it as a set of TLVs
+/// If `$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 `$field` is a Vec, which needs to have its individual elements serialized.
+///
+/// For example,
+/// ```
+/// # use lightning::impl_writeable_tlv_based;
+/// struct LightningMessage {
+///    tlv_integer: u32,
+///    tlv_default_integer: u32,
+///    tlv_optional_integer: Option<u32>,
+///    tlv_vec_type_integer: Vec<u32>,
+/// }
+///
+/// impl_writeable_tlv_based!(LightningMessage, {
+///    (0, tlv_integer, required),
+///    (1, tlv_default_integer, (default_value, 7)),
+///    (2, tlv_optional_integer, option),
+///    (3, tlv_vec_type_integer, vec_type),
+/// });
+/// ```
+///
+/// [`Readable`]: crate::util::ser::Readable
+/// [`Writeable`]: crate::util::ser::Writeable
+#[macro_export]
 macro_rules! impl_writeable_tlv_based {
        ($st: ident, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}) => {
                impl $crate::util::ser::Writeable for $st {
                        fn write<W: $crate::util::ser::Writer>(&self, writer: &mut W) -> Result<(), $crate::io::Error> {
-                               write_tlv_fields!(writer, {
+                               $crate::write_tlv_fields!(writer, {
                                        $(($type, self.$field, $fieldty)),*
                                });
                                Ok(())
@@ -496,7 +670,7 @@ macro_rules! impl_writeable_tlv_based {
                                        #[allow(unused_mut)]
                                        let mut len = $crate::util::ser::LengthCalculatingWriter(0);
                                        $(
-                                               get_varint_length_prefixed_tlv_length!(len, $type, self.$field, $fieldty);
+                                               $crate::_get_varint_length_prefixed_tlv_length!(len, $type, self.$field, $fieldty);
                                        )*
                                        len.0
                                };
@@ -508,12 +682,12 @@ macro_rules! impl_writeable_tlv_based {
 
                impl $crate::util::ser::Readable for $st {
                        fn read<R: $crate::io::Read>(reader: &mut R) -> Result<Self, $crate::ln::msgs::DecodeError> {
-                               init_and_read_tlv_fields!(reader, {
+                               $crate::_init_and_read_tlv_fields!(reader, {
                                        $(($type, $field, $fieldty)),*
                                });
                                Ok(Self {
                                        $(
-                                               $field: init_tlv_based_struct_field!($field, $fieldty)
+                                               $field: $crate::_init_tlv_based_struct_field!($field, $fieldty)
                                        ),*
                                })
                        }
@@ -560,12 +734,12 @@ macro_rules! tlv_stream {
                impl $crate::util::ser::SeekReadable for $name {
                        fn read<R: $crate::io::Read + $crate::io::Seek>(reader: &mut R) -> Result<Self, $crate::ln::msgs::DecodeError> {
                                $(
-                                       init_tlv_field_var!($field, option);
+                                       _init_tlv_field_var!($field, option);
                                )*
                                let rewind = |cursor: &mut R, offset: usize| {
                                        cursor.seek($crate::io::SeekFrom::Current(-(offset as i64))).expect("");
                                };
-                               decode_tlv_stream_range!(reader, $range, rewind, {
+                               _decode_tlv_stream_range!(reader, $range, rewind, {
                                        $(($type, $field, (option, encoding: $fieldty))),*
                                });
 
@@ -621,13 +795,18 @@ macro_rules! _impl_writeable_tlv_based_enum_common {
        }
 }
 
-/// Implement MaybeReadable and Writeable for an enum, with struct variants stored as TLVs and
+/// Implement [`MaybeReadable`] and [`Writeable`] for an enum, with struct variants stored as TLVs and
 /// tuple variants stored directly.
 ///
-/// This is largely identical to `impl_writeable_tlv_based_enum`, except that odd variants will
-/// return `Ok(None)` instead of `Err(UnknownRequiredFeature)`. It should generally be preferred
-/// when `MaybeReadable` is practical instead of just `Readable` as it provides an upgrade path for
+/// This is largely identical to [`impl_writeable_tlv_based_enum`], except that odd variants will
+/// return `Ok(None)` instead of `Err(`[`DecodeError::UnknownRequiredFeature`]`)`. It should generally be preferred
+/// when [`MaybeReadable`] is practical instead of just [`Readable`] as it provides an upgrade path for
 /// new variants to be added which are simply ignored by existing clients.
+///
+/// [`MaybeReadable`]: crate::util::ser::MaybeReadable
+/// [`Writeable`]: crate::util::ser::Writeable
+/// [`DecodeError::UnknownRequiredFeature`]: crate::ln::msgs::DecodeError::UnknownRequiredFeature
+/// [`Readable`]: crate::util::ser::Readable
 macro_rules! impl_writeable_tlv_based_enum_upgradable {
        ($st: ident, $(($variant_id: expr, $variant_name: ident) =>
                {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}
@@ -646,12 +825,12 @@ macro_rules! impl_writeable_tlv_based_enum_upgradable {
                                                // Because read_tlv_fields creates a labeled loop, we cannot call it twice
                                                // in the same function body. Instead, we define a closure and call it.
                                                let f = || {
-                                                       init_and_read_tlv_fields!(reader, {
+                                                       _init_and_read_tlv_fields!(reader, {
                                                                $(($type, $field, $fieldty)),*
                                                        });
                                                        Ok(Some($st::$variant_name {
                                                                $(
-                                                                       $field: init_tlv_based_struct_field!($field, $fieldty)
+                                                                       $field: _init_tlv_based_struct_field!($field, $fieldty)
                                                                ),*
                                                        }))
                                                };
@@ -669,7 +848,7 @@ macro_rules! impl_writeable_tlv_based_enum_upgradable {
        }
 }
 
-/// Implement Readable and Writeable for an enum, with struct variants stored as TLVs and tuple
+/// Implement [`Readable`] and [`Writeable`] for an enum, with struct variants stored as TLVs and tuple
 /// variants stored directly.
 /// The format is, for example
 /// impl_writeable_tlv_based_enum!(EnumName,
@@ -678,7 +857,11 @@ macro_rules! impl_writeable_tlv_based_enum_upgradable {
 ///   (2, TupleVariantA), (3, TupleVariantB),
 /// );
 /// The type is written as a single byte, followed by any variant data.
-/// Attempts to read an unknown type byte result in DecodeError::UnknownRequiredFeature.
+/// Attempts to read an unknown type byte result in [`DecodeError::UnknownRequiredFeature`].
+///
+/// [`Readable`]: crate::util::ser::Readable
+/// [`Writeable`]: crate::util::ser::Writeable
+/// [`DecodeError::UnknownRequiredFeature`]: crate::ln::msgs::DecodeError::UnknownRequiredFeature
 macro_rules! impl_writeable_tlv_based_enum {
        ($st: ident, $(($variant_id: expr, $variant_name: ident) =>
                {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}
@@ -696,12 +879,12 @@ macro_rules! impl_writeable_tlv_based_enum {
                                                // Because read_tlv_fields creates a labeled loop, we cannot call it twice
                                                // in the same function body. Instead, we define a closure and call it.
                                                let f = || {
-                                                       init_and_read_tlv_fields!(reader, {
+                                                       _init_and_read_tlv_fields!(reader, {
                                                                $(($type, $field, $fieldty)),*
                                                        });
                                                        Ok($st::$variant_name {
                                                                $(
-                                                                       $field: init_tlv_based_struct_field!($field, $fieldty)
+                                                                       $field: _init_tlv_based_struct_field!($field, $fieldty)
                                                                ),*
                                                        })
                                                };
@@ -910,27 +1093,27 @@ mod tests {
                let mut stream = VecWriter(Vec::new());
 
                stream.0.clear();
-               encode_varint_length_prefixed_tlv!(&mut stream, {(1, 1u8, required), (42, None::<u64>, option)});
+               _encode_varint_length_prefixed_tlv!(&mut stream, {(1, 1u8, required), (42, None::<u64>, option)});
                assert_eq!(stream.0, ::hex::decode("03010101").unwrap());
 
                stream.0.clear();
-               encode_varint_length_prefixed_tlv!(&mut stream, {(1, Some(1u8), option)});
+               _encode_varint_length_prefixed_tlv!(&mut stream, {(1, Some(1u8), option)});
                assert_eq!(stream.0, ::hex::decode("03010101").unwrap());
 
                stream.0.clear();
-               encode_varint_length_prefixed_tlv!(&mut stream, {(4, 0xabcdu16, required), (42, None::<u64>, option)});
+               _encode_varint_length_prefixed_tlv!(&mut stream, {(4, 0xabcdu16, required), (42, None::<u64>, option)});
                assert_eq!(stream.0, ::hex::decode("040402abcd").unwrap());
 
                stream.0.clear();
-               encode_varint_length_prefixed_tlv!(&mut stream, {(42, None::<u64>, option), (0xff, 0xabcdu16, required)});
+               _encode_varint_length_prefixed_tlv!(&mut stream, {(42, None::<u64>, option), (0xff, 0xabcdu16, required)});
                assert_eq!(stream.0, ::hex::decode("06fd00ff02abcd").unwrap());
 
                stream.0.clear();
-               encode_varint_length_prefixed_tlv!(&mut stream, {(0, 1u64, required), (42, None::<u64>, option), (0xff, HighZeroBytesDroppedBigSize(0u64), required)});
+               _encode_varint_length_prefixed_tlv!(&mut stream, {(0, 1u64, required), (42, None::<u64>, option), (0xff, HighZeroBytesDroppedBigSize(0u64), required)});
                assert_eq!(stream.0, ::hex::decode("0e00080000000000000001fd00ff00").unwrap());
 
                stream.0.clear();
-               encode_varint_length_prefixed_tlv!(&mut stream, {(0, Some(1u64), option), (0xff, HighZeroBytesDroppedBigSize(0u64), required)});
+               _encode_varint_length_prefixed_tlv!(&mut stream, {(0, Some(1u64), option), (0xff, HighZeroBytesDroppedBigSize(0u64), required)});
                assert_eq!(stream.0, ::hex::decode("0e00080000000000000001fd00ff00").unwrap());
 
                Ok(())