Implement `VecReadWrapper` for `MaybeReadable`

This makes it much simpler to deal with `MaybeReadable` types in
`Vec`s in TLVs as we can transparently deal with them as `vec`,
with the wrapper doing the Right Thing.

This requires we implement `MaybeReadable` for all `Readable` which
has some downstream implications, but nothing too bad.

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 7304c698ab185b0dfe6c4b90b6b18c9895a0765c..38e2172ed409c0eb684c5b0b1290820c47c23c49 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -1477,8 +1477,8 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 
                let mut chacha = ChaCha20::new(&rho, &[0u8; 8]);
                let mut chacha_stream = ChaChaReader { chacha: &mut chacha, read: Cursor::new(&msg.onion_routing_packet.hop_data[..]) };
-               let (next_hop_data, next_hop_hmac) = {
-                       match msgs::OnionHopData::read(&mut chacha_stream) {
+               let (next_hop_data, next_hop_hmac): (msgs::OnionHopData, _) = {
+                       match <msgs::OnionHopData as Readable>::read(&mut chacha_stream) {
                                Err(err) => {
                                        let error_code = match err {
                                                msgs::DecodeError::UnknownVersion => 0x4000 | 1, // unknown realm byte

diff --git a/lightning/src/util/ser.rs b/lightning/src/util/ser.rs
index b27cf4b348c3d98fc805dd7478dbe640910d80f4..a7f69fcfcb583b13c47179e8cd9f8ad12f9d2573 100644 (file)
--- a/lightning/src/util/ser.rs
+++ b/lightning/src/util/ser.rs
@@ -241,6 +241,13 @@ pub trait MaybeReadable
        fn read<R: Read>(reader: &mut R) -> Result<Option<Self>, DecodeError>;
 }
 
+impl<T: Readable> MaybeReadable for T {
+       #[inline]
+       fn read<R: Read>(reader: &mut R) -> Result<Option<T>, DecodeError> {
+               Ok(Some(Readable::read(reader)?))
+       }
+}
+
 pub(crate) struct OptionDeserWrapper<T: Readable>(pub Option<T>);
 impl<T: Readable> Readable for OptionDeserWrapper<T> {
        #[inline]
@@ -262,15 +269,16 @@ impl<'a, T: Writeable> Writeable for VecWriteWrapper<'a, T> {
 }
 
 /// Wrapper to read elements from a given stream until it reaches the end of the stream.
-pub(crate) struct VecReadWrapper<T: Readable>(pub Vec<T>);
-impl<T: Readable> Readable for VecReadWrapper<T> {
+pub(crate) struct VecReadWrapper<T>(pub Vec<T>);
+impl<T: MaybeReadable> Readable for VecReadWrapper<T> {
        #[inline]
        fn read<R: Read>(mut reader: &mut R) -> Result<Self, DecodeError> {
                let mut values = Vec::new();
                loop {
                        let mut track_read = ReadTrackingReader::new(&mut reader);
-                       match Readable::read(&mut track_read) {
-                               Ok(v) => { values.push(v); },
+                       match MaybeReadable::read(&mut track_read) {
+                               Ok(Some(v)) => { values.push(v); },
+                               Ok(None) => { },
                                // If we failed to read any bytes at all, we reached the end of our TLV
                                // stream and have simply exhausted all entries.
                                Err(ref e) if e == &DecodeError::ShortRead && !track_read.have_read => break,
@@ -561,7 +569,7 @@ impl Readable for Vec<Signature> {
                        return Err(DecodeError::BadLengthDescriptor);
                }
                let mut ret = Vec::with_capacity(len as usize);
-               for _ in 0..len { ret.push(Signature::read(r)?); }
+               for _ in 0..len { ret.push(Readable::read(r)?); }
                Ok(ret)
        }
 }
@@ -726,7 +734,8 @@ impl<T: Writeable> Writeable for Option<T> {
 impl<T: Readable> Readable for Option<T>
 {
        fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
-               match BigSize::read(r)?.0 {
+               let len: BigSize = Readable::read(r)?;
+               match len.0 {
                        0 => Ok(None),
                        len => {
                                let mut reader = FixedLengthReader::new(r, len - 1);

diff --git a/lightning/src/util/ser_macros.rs b/lightning/src/util/ser_macros.rs
index 960fae45d26181d806e95c3da1884aa7be3f930a..e988ad7eeab940d0e6979904c63dcd88087f023e 100644 (file)
--- a/lightning/src/util/ser_macros.rs
+++ b/lightning/src/util/ser_macros.rs
@@ -371,7 +371,7 @@ macro_rules! read_ver_prefix {
 /// Reads a suffix added by write_tlv_fields.
 macro_rules! read_tlv_fields {
        ($stream: expr, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}) => { {
-               let tlv_len = ::util::ser::BigSize::read($stream)?;
+               let tlv_len: ::util::ser::BigSize = ::util::ser::Readable::read($stream)?;
                let mut rd = ::util::ser::FixedLengthReader::new($stream, tlv_len.0);
                decode_tlv_stream!(&mut rd, {$(($type, $field, $fieldty)),*});
                rd.eat_remaining().map_err(|_| ::ln::msgs::DecodeError::ShortRead)?;