Trivial Serialization Tweaks

lightning/src/util/ser.rs

@@ -22,6 +22,8 @@ use core::cmp;
 use core::convert::TryFrom;
 use core::ops::Deref;
 
+use alloc::collections::BTreeMap;
+
 use bitcoin::secp256k1::{PublicKey, SecretKey};
 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
 use bitcoin::secp256k1::ecdsa;
@@ -381,6 +383,40 @@ impl Readable for BigSize {
 	}
 }
 
+/// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
+/// primarily targets that, we must as well. However, because we may serialize objects that have
+/// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
+/// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
+/// "read eight more bytes".
+///
+/// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
+/// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
+/// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
+struct CollectionLength(pub u64);
+impl Writeable for CollectionLength {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+ if self.0 < 0xffff {
+ (self.0 as u16).write(writer)
+ } else {
+ 0xffffu16.write(writer)?;
+ (self.0 - 0xffff).write(writer)
+ }
+	}
+}
+
+impl Readable for CollectionLength {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let mut val: u64 = <u16 as Readable>::read(r)? as u64;
+ if val == 0xffff {
+ val = <u64 as Readable>::read(r)?
+ .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
+ }
+ Ok(CollectionLength(val))
+	}
+}
+
 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
@@ -588,50 +624,54 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
-// HashMap
-impl<K, V> Writeable for HashMap<K, V>
-	where K: Writeable + Eq + Hash,
- V: Writeable
-{
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-	(self.len() as u16).write(w)?;
- for (key, value) in self.iter() {
- key.write(w)?;
- value.write(w)?;
+macro_rules! impl_for_map {
+	($ty: ident, $keybound: ident, $constr: expr) => {
+ impl<K, V> Writeable for $ty<K, V>
+ where K: Writeable + Eq + $keybound, V: Writeable
+ {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for (key, value) in self.iter() {
+ key.write(w)?;
+ value.write(w)?;
+ }
+ Ok(())
+ }
  }
- Ok(())
-	}
-}
 
-impl<K, V> Readable for HashMap<K, V>
-	where K: Readable + Eq + Hash,
- V: MaybeReadable
-{
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashMap::with_capacity(len as usize);
- for _ in 0..len {
- let k = K::read(r)?;
- let v_opt = V::read(r)?;
- if let Some(v) = v_opt {
- if ret.insert(k, v).is_some() {
- return Err(DecodeError::InvalidValue);
+ impl<K, V> Readable for $ty<K, V>
+ where K: Readable + Eq + $keybound, V: MaybeReadable
+ {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = $constr(len.0 as usize);
+ for _ in 0..len.0 {
+ let k = K::read(r)?;
+ let v_opt = V::read(r)?;
+ if let Some(v) = v_opt {
+ if ret.insert(k, v).is_some() {
+ return Err(DecodeError::InvalidValue);
+ }
+ }
  }
+ Ok(ret)
  }
  }
- Ok(ret)
 	}
 }
 
+impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
+impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
+
 // HashSet
 impl<T> Writeable for HashSet<T>
 where T: Writeable + Eq + Hash
 {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  for item in self.iter() {
  item.write(w)?;
  }
@@ -644,9 +684,9 @@ where T: Readable + Eq + Hash
 {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashSet::with_capacity(len as usize);
- for _ in 0..len {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
+ for _ in 0..len.0 {
  if !ret.insert(T::read(r)?) {
  return Err(DecodeError::InvalidValue)
  }
@@ -656,51 +696,62 @@ where T: Readable + Eq + Hash
 }
 
 // Vectors
-impl Writeable for Vec<u8> {
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- w.write_all(&self)
-	}
-}
+macro_rules! impl_for_vec {
+	($ty: ty $(, $name: ident)*) => {
+ impl<$($name : Writeable),*> Writeable for Vec<$ty> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for elem in self.iter() {
+ elem.write(w)?;
+ }
+ Ok(())
+ }
+ }
 
-impl Readable for Vec<u8> {
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = Vec::with_capacity(len as usize);
- ret.resize(len as usize, 0);
- r.read_exact(&mut ret)?;
- Ok(ret)
+ impl<$($name : Readable),*> Readable for Vec<$ty> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
+ for _ in 0..len.0 {
+ if let Some(val) = MaybeReadable::read(r)? {
+ ret.push(val);
+ }
+ }
+ Ok(ret)
+ }
+ }
 	}
 }
-impl Writeable for Vec<ecdsa::Signature> {
+
+impl Writeable for Vec<u8> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- for e in self.iter() {
- e.write(w)?;
- }
- Ok(())
+ CollectionLength(self.len() as u64).write(w)?;
+ w.write_all(&self)
 	}
 }
 
-impl Readable for Vec<ecdsa::Signature> {
+impl Readable for Vec<u8> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let byte_size = (len as usize)
- .checked_mul(COMPACT_SIGNATURE_SIZE)
- .ok_or(DecodeError::BadLengthDescriptor)?;
- if byte_size > MAX_BUF_SIZE {
- return Err(DecodeError::BadLengthDescriptor);
+ let mut len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::new();
+ while len.0 > 0 {
+ let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
+ let readstart = ret.len();
+ ret.resize(readstart + readamt, 0);
+ r.read_exact(&mut ret[readstart..])?;
+ len.0 -= readamt as u64;
  }
- let mut ret = Vec::with_capacity(len as usize);
- for _ in 0..len { ret.push(Readable::read(r)?); }
  Ok(ret)
 	}
 }
 
+impl_for_vec!(ecdsa::Signature);
+impl_for_vec!((A, B), A, B);
+
 impl Writeable for Script {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  (self.len() as u16).write(w)?;
@@ -1028,7 +1079,7 @@ impl Readable for () {
 impl Writeable for String {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  w.write_all(self.as_bytes())
 	}
 }

lightning/src/util/ser_macros.rs

@@ -39,6 +39,9 @@ macro_rules! _encode_tlv {
  field.write($stream)?;
  }
 	};
+	($stream: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_encode_tlv!($stream, $type, $field, required);
+	};
 	($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
  $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
 	};
@@ -155,6 +158,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
  $len.0 += field_len;
  }
 	};
+	($len: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
+	};
 }
 
 /// See the documentation of [`write_tlv_fields`].
@@ -581,6 +587,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
  $field
 	};
+	($field: ident, ignorable) => {
+ if $field.is_none() { return Ok(None); } else { $field.unwrap() }
+	};
 	($field: ident, required) => {
  $field.0.unwrap()
 	};
@@ -610,6 +619,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
  let mut $field = None;
 	};
+	($field: ident, ignorable) => {
+ let mut $field = None;
+	};
 }
 
 /// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].

lightning/src/util/ser.rs

@@ -22,6 +22,8 @@ use core::cmp;
 use core::convert::TryFrom;
 use core::ops::Deref;
 
+use alloc::collections::BTreeMap;
+
 use bitcoin::secp256k1::{PublicKey, SecretKey};
 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
 use bitcoin::secp256k1::ecdsa;
@@ -381,6 +383,40 @@ impl Readable for BigSize {
 	}
 }
 
+/// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
+/// primarily targets that, we must as well. However, because we may serialize objects that have
+/// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
+/// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
+/// "read eight more bytes".
+///
+/// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
+/// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
+/// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
+struct CollectionLength(pub u64);
+impl Writeable for CollectionLength {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+ if self.0 < 0xffff {
+ (self.0 as u16).write(writer)
+ } else {
+ 0xffffu16.write(writer)?;
+ (self.0 - 0xffff).write(writer)
+ }
+	}
+}
+
+impl Readable for CollectionLength {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let mut val: u64 = <u16 as Readable>::read(r)? as u64;
+ if val == 0xffff {
+ val = <u64 as Readable>::read(r)?
+ .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
+ }
+ Ok(CollectionLength(val))
+	}
+}
+
 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
@@ -588,50 +624,54 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
-// HashMap
-impl<K, V> Writeable for HashMap<K, V>
-	where K: Writeable + Eq + Hash,
- V: Writeable
-{
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-	(self.len() as u16).write(w)?;
- for (key, value) in self.iter() {
- key.write(w)?;
- value.write(w)?;
+macro_rules! impl_for_map {
+	($ty: ident, $keybound: ident, $constr: expr) => {
+ impl<K, V> Writeable for $ty<K, V>
+ where K: Writeable + Eq + $keybound, V: Writeable
+ {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for (key, value) in self.iter() {
+ key.write(w)?;
+ value.write(w)?;
+ }
+ Ok(())
+ }
  }
- Ok(())
-	}
-}
 
-impl<K, V> Readable for HashMap<K, V>
-	where K: Readable + Eq + Hash,
- V: MaybeReadable
-{
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashMap::with_capacity(len as usize);
- for _ in 0..len {
- let k = K::read(r)?;
- let v_opt = V::read(r)?;
- if let Some(v) = v_opt {
- if ret.insert(k, v).is_some() {
- return Err(DecodeError::InvalidValue);
+ impl<K, V> Readable for $ty<K, V>
+ where K: Readable + Eq + $keybound, V: MaybeReadable
+ {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = $constr(len.0 as usize);
+ for _ in 0..len.0 {
+ let k = K::read(r)?;
+ let v_opt = V::read(r)?;
+ if let Some(v) = v_opt {
+ if ret.insert(k, v).is_some() {
+ return Err(DecodeError::InvalidValue);
+ }
+ }
  }
+ Ok(ret)
  }
  }
- Ok(ret)
 	}
 }
 
+impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
+impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
+
 // HashSet
 impl<T> Writeable for HashSet<T>
 where T: Writeable + Eq + Hash
 {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  for item in self.iter() {
  item.write(w)?;
  }
@@ -644,9 +684,9 @@ where T: Readable + Eq + Hash
 {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashSet::with_capacity(len as usize);
- for _ in 0..len {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
+ for _ in 0..len.0 {
  if !ret.insert(T::read(r)?) {
  return Err(DecodeError::InvalidValue)
  }
@@ -656,51 +696,62 @@ where T: Readable + Eq + Hash
 }
 
 // Vectors
-impl Writeable for Vec<u8> {
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- w.write_all(&self)
-	}
-}
+macro_rules! impl_for_vec {
+	($ty: ty $(, $name: ident)*) => {
+ impl<$($name : Writeable),*> Writeable for Vec<$ty> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for elem in self.iter() {
+ elem.write(w)?;
+ }
+ Ok(())
+ }
+ }
 
-impl Readable for Vec<u8> {
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = Vec::with_capacity(len as usize);
- ret.resize(len as usize, 0);
- r.read_exact(&mut ret)?;
- Ok(ret)
+ impl<$($name : Readable),*> Readable for Vec<$ty> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
+ for _ in 0..len.0 {
+ if let Some(val) = MaybeReadable::read(r)? {
+ ret.push(val);
+ }
+ }
+ Ok(ret)
+ }
+ }
 	}
 }
-impl Writeable for Vec<ecdsa::Signature> {
+
+impl Writeable for Vec<u8> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- for e in self.iter() {
- e.write(w)?;
- }
- Ok(())
+ CollectionLength(self.len() as u64).write(w)?;
+ w.write_all(&self)
 	}
 }
 
-impl Readable for Vec<ecdsa::Signature> {
+impl Readable for Vec<u8> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let byte_size = (len as usize)
- .checked_mul(COMPACT_SIGNATURE_SIZE)
- .ok_or(DecodeError::BadLengthDescriptor)?;
- if byte_size > MAX_BUF_SIZE {
- return Err(DecodeError::BadLengthDescriptor);
+ let mut len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::new();
+ while len.0 > 0 {
+ let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
+ let readstart = ret.len();
+ ret.resize(readstart + readamt, 0);
+ r.read_exact(&mut ret[readstart..])?;
+ len.0 -= readamt as u64;
  }
- let mut ret = Vec::with_capacity(len as usize);
- for _ in 0..len { ret.push(Readable::read(r)?); }
  Ok(ret)
 	}
 }
 
+impl_for_vec!(ecdsa::Signature);
+impl_for_vec!((A, B), A, B);
+
 impl Writeable for Script {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  (self.len() as u16).write(w)?;
@@ -1028,7 +1079,7 @@ impl Readable for () {
 impl Writeable for String {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  w.write_all(self.as_bytes())
 	}
 }

lightning/src/util/ser_macros.rs

@@ -39,6 +39,9 @@ macro_rules! _encode_tlv {
  field.write($stream)?;
  }
 	};
+	($stream: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_encode_tlv!($stream, $type, $field, required);
+	};
 	($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
  $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
 	};
@@ -155,6 +158,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
  $len.0 += field_len;
  }
 	};
+	($len: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
+	};
 }
 
 /// See the documentation of [`write_tlv_fields`].
@@ -581,6 +587,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
  $field
 	};
+	($field: ident, ignorable) => {
+ if $field.is_none() { return Ok(None); } else { $field.unwrap() }
+	};
 	($field: ident, required) => {
  $field.0.unwrap()
 	};
@@ -610,6 +619,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
  let mut $field = None;
 	};
+	($field: ident, ignorable) => {
+ let mut $field = None;
+	};
 }
 
 /// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].

lightning/src/util/ser.rs

@@ -22,6 +22,8 @@ use core::cmp;
 use core::convert::TryFrom;
 use core::ops::Deref;
 
+use alloc::collections::BTreeMap;
+
 use bitcoin::secp256k1::{PublicKey, SecretKey};
 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
 use bitcoin::secp256k1::ecdsa;
@@ -381,6 +383,40 @@ impl Readable for BigSize {
 	}
 }
 
+/// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
+/// primarily targets that, we must as well. However, because we may serialize objects that have
+/// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
+/// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
+/// "read eight more bytes".
+///
+/// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
+/// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
+/// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
+struct CollectionLength(pub u64);
+impl Writeable for CollectionLength {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+ if self.0 < 0xffff {
+ (self.0 as u16).write(writer)
+ } else {
+ 0xffffu16.write(writer)?;
+ (self.0 - 0xffff).write(writer)
+ }
+	}
+}
+
+impl Readable for CollectionLength {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let mut val: u64 = <u16 as Readable>::read(r)? as u64;
+ if val == 0xffff {
+ val = <u64 as Readable>::read(r)?
+ .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
+ }
+ Ok(CollectionLength(val))
+	}
+}
+
 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
@@ -588,50 +624,54 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
-// HashMap
-impl<K, V> Writeable for HashMap<K, V>
-	where K: Writeable + Eq + Hash,
- V: Writeable
-{
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-	(self.len() as u16).write(w)?;
- for (key, value) in self.iter() {
- key.write(w)?;
- value.write(w)?;
+macro_rules! impl_for_map {
+	($ty: ident, $keybound: ident, $constr: expr) => {
+ impl<K, V> Writeable for $ty<K, V>
+ where K: Writeable + Eq + $keybound, V: Writeable
+ {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for (key, value) in self.iter() {
+ key.write(w)?;
+ value.write(w)?;
+ }
+ Ok(())
+ }
  }
- Ok(())
-	}
-}
 
-impl<K, V> Readable for HashMap<K, V>
-	where K: Readable + Eq + Hash,
- V: MaybeReadable
-{
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashMap::with_capacity(len as usize);
- for _ in 0..len {
- let k = K::read(r)?;
- let v_opt = V::read(r)?;
- if let Some(v) = v_opt {
- if ret.insert(k, v).is_some() {
- return Err(DecodeError::InvalidValue);
+ impl<K, V> Readable for $ty<K, V>
+ where K: Readable + Eq + $keybound, V: MaybeReadable
+ {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = $constr(len.0 as usize);
+ for _ in 0..len.0 {
+ let k = K::read(r)?;
+ let v_opt = V::read(r)?;
+ if let Some(v) = v_opt {
+ if ret.insert(k, v).is_some() {
+ return Err(DecodeError::InvalidValue);
+ }
+ }
  }
+ Ok(ret)
  }
  }
- Ok(ret)
 	}
 }
 
+impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
+impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
+
 // HashSet
 impl<T> Writeable for HashSet<T>
 where T: Writeable + Eq + Hash
 {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  for item in self.iter() {
  item.write(w)?;
  }
@@ -644,9 +684,9 @@ where T: Readable + Eq + Hash
 {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashSet::with_capacity(len as usize);
- for _ in 0..len {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
+ for _ in 0..len.0 {
  if !ret.insert(T::read(r)?) {
  return Err(DecodeError::InvalidValue)
  }
@@ -656,51 +696,62 @@ where T: Readable + Eq + Hash
 }
 
 // Vectors
-impl Writeable for Vec<u8> {
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- w.write_all(&self)
-	}
-}
+macro_rules! impl_for_vec {
+	($ty: ty $(, $name: ident)*) => {
+ impl<$($name : Writeable),*> Writeable for Vec<$ty> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for elem in self.iter() {
+ elem.write(w)?;
+ }
+ Ok(())
+ }
+ }
 
-impl Readable for Vec<u8> {
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = Vec::with_capacity(len as usize);
- ret.resize(len as usize, 0);
- r.read_exact(&mut ret)?;
- Ok(ret)
+ impl<$($name : Readable),*> Readable for Vec<$ty> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
+ for _ in 0..len.0 {
+ if let Some(val) = MaybeReadable::read(r)? {
+ ret.push(val);
+ }
+ }
+ Ok(ret)
+ }
+ }
 	}
 }
-impl Writeable for Vec<ecdsa::Signature> {
+
+impl Writeable for Vec<u8> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- for e in self.iter() {
- e.write(w)?;
- }
- Ok(())
+ CollectionLength(self.len() as u64).write(w)?;
+ w.write_all(&self)
 	}
 }
 
-impl Readable for Vec<ecdsa::Signature> {
+impl Readable for Vec<u8> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let byte_size = (len as usize)
- .checked_mul(COMPACT_SIGNATURE_SIZE)
- .ok_or(DecodeError::BadLengthDescriptor)?;
- if byte_size > MAX_BUF_SIZE {
- return Err(DecodeError::BadLengthDescriptor);
+ let mut len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::new();
+ while len.0 > 0 {
+ let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
+ let readstart = ret.len();
+ ret.resize(readstart + readamt, 0);
+ r.read_exact(&mut ret[readstart..])?;
+ len.0 -= readamt as u64;
  }
- let mut ret = Vec::with_capacity(len as usize);
- for _ in 0..len { ret.push(Readable::read(r)?); }
  Ok(ret)
 	}
 }
 
+impl_for_vec!(ecdsa::Signature);
+impl_for_vec!((A, B), A, B);
+
 impl Writeable for Script {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  (self.len() as u16).write(w)?;
@@ -1028,7 +1079,7 @@ impl Readable for () {
 impl Writeable for String {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  w.write_all(self.as_bytes())
 	}
 }

lightning/src/util/ser_macros.rs

@@ -39,6 +39,9 @@ macro_rules! _encode_tlv {
  field.write($stream)?;
  }
 	};
+	($stream: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_encode_tlv!($stream, $type, $field, required);
+	};
 	($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
  $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
 	};
@@ -155,6 +158,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
  $len.0 += field_len;
  }
 	};
+	($len: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
+	};
 }
 
 /// See the documentation of [`write_tlv_fields`].
@@ -581,6 +587,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
  $field
 	};
+	($field: ident, ignorable) => {
+ if $field.is_none() { return Ok(None); } else { $field.unwrap() }
+	};
 	($field: ident, required) => {
  $field.0.unwrap()
 	};
@@ -610,6 +619,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
  let mut $field = None;
 	};
+	($field: ident, ignorable) => {
+ let mut $field = None;
+	};
 }
 
 /// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].

lightning/src/util/ser.rs

@@ -22,6 +22,8 @@ use core::cmp;
 use core::convert::TryFrom;
 use core::ops::Deref;
 
+use alloc::collections::BTreeMap;
+
 use bitcoin::secp256k1::{PublicKey, SecretKey};
 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
 use bitcoin::secp256k1::ecdsa;
@@ -381,6 +383,40 @@ impl Readable for BigSize {
 	}
 }
 
+/// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
+/// primarily targets that, we must as well. However, because we may serialize objects that have
+/// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
+/// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
+/// "read eight more bytes".
+///
+/// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
+/// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
+/// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
+struct CollectionLength(pub u64);
+impl Writeable for CollectionLength {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+ if self.0 < 0xffff {
+ (self.0 as u16).write(writer)
+ } else {
+ 0xffffu16.write(writer)?;
+ (self.0 - 0xffff).write(writer)
+ }
+	}
+}
+
+impl Readable for CollectionLength {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let mut val: u64 = <u16 as Readable>::read(r)? as u64;
+ if val == 0xffff {
+ val = <u64 as Readable>::read(r)?
+ .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
+ }
+ Ok(CollectionLength(val))
+	}
+}
+
 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
@@ -588,50 +624,54 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
-// HashMap
-impl<K, V> Writeable for HashMap<K, V>
-	where K: Writeable + Eq + Hash,
- V: Writeable
-{
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-	(self.len() as u16).write(w)?;
- for (key, value) in self.iter() {
- key.write(w)?;
- value.write(w)?;
+macro_rules! impl_for_map {
+	($ty: ident, $keybound: ident, $constr: expr) => {
+ impl<K, V> Writeable for $ty<K, V>
+ where K: Writeable + Eq + $keybound, V: Writeable
+ {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for (key, value) in self.iter() {
+ key.write(w)?;
+ value.write(w)?;
+ }
+ Ok(())
+ }
  }
- Ok(())
-	}
-}
 
-impl<K, V> Readable for HashMap<K, V>
-	where K: Readable + Eq + Hash,
- V: MaybeReadable
-{
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashMap::with_capacity(len as usize);
- for _ in 0..len {
- let k = K::read(r)?;
- let v_opt = V::read(r)?;
- if let Some(v) = v_opt {
- if ret.insert(k, v).is_some() {
- return Err(DecodeError::InvalidValue);
+ impl<K, V> Readable for $ty<K, V>
+ where K: Readable + Eq + $keybound, V: MaybeReadable
+ {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = $constr(len.0 as usize);
+ for _ in 0..len.0 {
+ let k = K::read(r)?;
+ let v_opt = V::read(r)?;
+ if let Some(v) = v_opt {
+ if ret.insert(k, v).is_some() {
+ return Err(DecodeError::InvalidValue);
+ }
+ }
  }
+ Ok(ret)
  }
  }
- Ok(ret)
 	}
 }
 
+impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
+impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
+
 // HashSet
 impl<T> Writeable for HashSet<T>
 where T: Writeable + Eq + Hash
 {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  for item in self.iter() {
  item.write(w)?;
  }
@@ -644,9 +684,9 @@ where T: Readable + Eq + Hash
 {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashSet::with_capacity(len as usize);
- for _ in 0..len {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
+ for _ in 0..len.0 {
  if !ret.insert(T::read(r)?) {
  return Err(DecodeError::InvalidValue)
  }
@@ -656,51 +696,62 @@ where T: Readable + Eq + Hash
 }
 
 // Vectors
-impl Writeable for Vec<u8> {
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- w.write_all(&self)
-	}
-}
+macro_rules! impl_for_vec {
+	($ty: ty $(, $name: ident)*) => {
+ impl<$($name : Writeable),*> Writeable for Vec<$ty> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for elem in self.iter() {
+ elem.write(w)?;
+ }
+ Ok(())
+ }
+ }
 
-impl Readable for Vec<u8> {
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = Vec::with_capacity(len as usize);
- ret.resize(len as usize, 0);
- r.read_exact(&mut ret)?;
- Ok(ret)
+ impl<$($name : Readable),*> Readable for Vec<$ty> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
+ for _ in 0..len.0 {
+ if let Some(val) = MaybeReadable::read(r)? {
+ ret.push(val);
+ }
+ }
+ Ok(ret)
+ }
+ }
 	}
 }
-impl Writeable for Vec<ecdsa::Signature> {
+
+impl Writeable for Vec<u8> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- for e in self.iter() {
- e.write(w)?;
- }
- Ok(())
+ CollectionLength(self.len() as u64).write(w)?;
+ w.write_all(&self)
 	}
 }
 
-impl Readable for Vec<ecdsa::Signature> {
+impl Readable for Vec<u8> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let byte_size = (len as usize)
- .checked_mul(COMPACT_SIGNATURE_SIZE)
- .ok_or(DecodeError::BadLengthDescriptor)?;
- if byte_size > MAX_BUF_SIZE {
- return Err(DecodeError::BadLengthDescriptor);
+ let mut len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::new();
+ while len.0 > 0 {
+ let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
+ let readstart = ret.len();
+ ret.resize(readstart + readamt, 0);
+ r.read_exact(&mut ret[readstart..])?;
+ len.0 -= readamt as u64;
  }
- let mut ret = Vec::with_capacity(len as usize);
- for _ in 0..len { ret.push(Readable::read(r)?); }
  Ok(ret)
 	}
 }
 
+impl_for_vec!(ecdsa::Signature);
+impl_for_vec!((A, B), A, B);
+
 impl Writeable for Script {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  (self.len() as u16).write(w)?;
@@ -1028,7 +1079,7 @@ impl Readable for () {
 impl Writeable for String {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  w.write_all(self.as_bytes())
 	}
 }

lightning/src/util/ser_macros.rs

@@ -39,6 +39,9 @@ macro_rules! _encode_tlv {
  field.write($stream)?;
  }
 	};
+	($stream: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_encode_tlv!($stream, $type, $field, required);
+	};
 	($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
  $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
 	};
@@ -155,6 +158,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
  $len.0 += field_len;
  }
 	};
+	($len: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
+	};
 }
 
 /// See the documentation of [`write_tlv_fields`].
@@ -581,6 +587,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
  $field
 	};
+	($field: ident, ignorable) => {
+ if $field.is_none() { return Ok(None); } else { $field.unwrap() }
+	};
 	($field: ident, required) => {
  $field.0.unwrap()
 	};
@@ -610,6 +619,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
  let mut $field = None;
 	};
+	($field: ident, ignorable) => {
+ let mut $field = None;
+	};
 }
 
 /// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].

lightning/src/util/ser.rs

@@ -22,6 +22,8 @@ use core::cmp;
 use core::convert::TryFrom;
 use core::ops::Deref;
 
+use alloc::collections::BTreeMap;
+
 use bitcoin::secp256k1::{PublicKey, SecretKey};
 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
 use bitcoin::secp256k1::ecdsa;
@@ -381,6 +383,40 @@ impl Readable for BigSize {
 	}
 }
 
+/// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
+/// primarily targets that, we must as well. However, because we may serialize objects that have
+/// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
+/// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
+/// "read eight more bytes".
+///
+/// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
+/// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
+/// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
+struct CollectionLength(pub u64);
+impl Writeable for CollectionLength {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+ if self.0 < 0xffff {
+ (self.0 as u16).write(writer)
+ } else {
+ 0xffffu16.write(writer)?;
+ (self.0 - 0xffff).write(writer)
+ }
+	}
+}
+
+impl Readable for CollectionLength {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let mut val: u64 = <u16 as Readable>::read(r)? as u64;
+ if val == 0xffff {
+ val = <u64 as Readable>::read(r)?
+ .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
+ }
+ Ok(CollectionLength(val))
+	}
+}
+
 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
@@ -588,50 +624,54 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
-// HashMap
-impl<K, V> Writeable for HashMap<K, V>
-	where K: Writeable + Eq + Hash,
- V: Writeable
-{
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-	(self.len() as u16).write(w)?;
- for (key, value) in self.iter() {
- key.write(w)?;
- value.write(w)?;
+macro_rules! impl_for_map {
+	($ty: ident, $keybound: ident, $constr: expr) => {
+ impl<K, V> Writeable for $ty<K, V>
+ where K: Writeable + Eq + $keybound, V: Writeable
+ {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for (key, value) in self.iter() {
+ key.write(w)?;
+ value.write(w)?;
+ }
+ Ok(())
+ }
  }
- Ok(())
-	}
-}
 
-impl<K, V> Readable for HashMap<K, V>
-	where K: Readable + Eq + Hash,
- V: MaybeReadable
-{
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashMap::with_capacity(len as usize);
- for _ in 0..len {
- let k = K::read(r)?;
- let v_opt = V::read(r)?;
- if let Some(v) = v_opt {
- if ret.insert(k, v).is_some() {
- return Err(DecodeError::InvalidValue);
+ impl<K, V> Readable for $ty<K, V>
+ where K: Readable + Eq + $keybound, V: MaybeReadable
+ {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = $constr(len.0 as usize);
+ for _ in 0..len.0 {
+ let k = K::read(r)?;
+ let v_opt = V::read(r)?;
+ if let Some(v) = v_opt {
+ if ret.insert(k, v).is_some() {
+ return Err(DecodeError::InvalidValue);
+ }
+ }
  }
+ Ok(ret)
  }
  }
- Ok(ret)
 	}
 }
 
+impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
+impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
+
 // HashSet
 impl<T> Writeable for HashSet<T>
 where T: Writeable + Eq + Hash
 {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  for item in self.iter() {
  item.write(w)?;
  }
@@ -644,9 +684,9 @@ where T: Readable + Eq + Hash
 {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashSet::with_capacity(len as usize);
- for _ in 0..len {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
+ for _ in 0..len.0 {
  if !ret.insert(T::read(r)?) {
  return Err(DecodeError::InvalidValue)
  }
@@ -656,51 +696,62 @@ where T: Readable + Eq + Hash
 }
 
 // Vectors
-impl Writeable for Vec<u8> {
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- w.write_all(&self)
-	}
-}
+macro_rules! impl_for_vec {
+	($ty: ty $(, $name: ident)*) => {
+ impl<$($name : Writeable),*> Writeable for Vec<$ty> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for elem in self.iter() {
+ elem.write(w)?;
+ }
+ Ok(())
+ }
+ }
 
-impl Readable for Vec<u8> {
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = Vec::with_capacity(len as usize);
- ret.resize(len as usize, 0);
- r.read_exact(&mut ret)?;
- Ok(ret)
+ impl<$($name : Readable),*> Readable for Vec<$ty> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
+ for _ in 0..len.0 {
+ if let Some(val) = MaybeReadable::read(r)? {
+ ret.push(val);
+ }
+ }
+ Ok(ret)
+ }
+ }
 	}
 }
-impl Writeable for Vec<ecdsa::Signature> {
+
+impl Writeable for Vec<u8> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- for e in self.iter() {
- e.write(w)?;
- }
- Ok(())
+ CollectionLength(self.len() as u64).write(w)?;
+ w.write_all(&self)
 	}
 }
 
-impl Readable for Vec<ecdsa::Signature> {
+impl Readable for Vec<u8> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let byte_size = (len as usize)
- .checked_mul(COMPACT_SIGNATURE_SIZE)
- .ok_or(DecodeError::BadLengthDescriptor)?;
- if byte_size > MAX_BUF_SIZE {
- return Err(DecodeError::BadLengthDescriptor);
+ let mut len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::new();
+ while len.0 > 0 {
+ let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
+ let readstart = ret.len();
+ ret.resize(readstart + readamt, 0);
+ r.read_exact(&mut ret[readstart..])?;
+ len.0 -= readamt as u64;
  }
- let mut ret = Vec::with_capacity(len as usize);
- for _ in 0..len { ret.push(Readable::read(r)?); }
  Ok(ret)
 	}
 }
 
+impl_for_vec!(ecdsa::Signature);
+impl_for_vec!((A, B), A, B);
+
 impl Writeable for Script {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  (self.len() as u16).write(w)?;
@@ -1028,7 +1079,7 @@ impl Readable for () {
 impl Writeable for String {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  w.write_all(self.as_bytes())
 	}
 }

lightning/src/util/ser_macros.rs

@@ -39,6 +39,9 @@ macro_rules! _encode_tlv {
  field.write($stream)?;
  }
 	};
+	($stream: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_encode_tlv!($stream, $type, $field, required);
+	};
 	($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
  $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
 	};
@@ -155,6 +158,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
  $len.0 += field_len;
  }
 	};
+	($len: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
+	};
 }
 
 /// See the documentation of [`write_tlv_fields`].
@@ -581,6 +587,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
  $field
 	};
+	($field: ident, ignorable) => {
+ if $field.is_none() { return Ok(None); } else { $field.unwrap() }
+	};
 	($field: ident, required) => {
  $field.0.unwrap()
 	};
@@ -610,6 +619,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
  let mut $field = None;
 	};
+	($field: ident, ignorable) => {
+ let mut $field = None;
+	};
 }
 
 /// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].

lightning/src/util/ser.rs

@@ -22,6 +22,8 @@ use core::cmp;
 use core::convert::TryFrom;
 use core::ops::Deref;
 
+use alloc::collections::BTreeMap;
+
 use bitcoin::secp256k1::{PublicKey, SecretKey};
 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
 use bitcoin::secp256k1::ecdsa;
@@ -381,6 +383,40 @@ impl Readable for BigSize {
 	}
 }
 
+/// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
+/// primarily targets that, we must as well. However, because we may serialize objects that have
+/// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
+/// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
+/// "read eight more bytes".
+///
+/// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
+/// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
+/// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
+struct CollectionLength(pub u64);
+impl Writeable for CollectionLength {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+ if self.0 < 0xffff {
+ (self.0 as u16).write(writer)
+ } else {
+ 0xffffu16.write(writer)?;
+ (self.0 - 0xffff).write(writer)
+ }
+	}
+}
+
+impl Readable for CollectionLength {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let mut val: u64 = <u16 as Readable>::read(r)? as u64;
+ if val == 0xffff {
+ val = <u64 as Readable>::read(r)?
+ .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
+ }
+ Ok(CollectionLength(val))
+	}
+}
+
 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
@@ -588,50 +624,54 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
-// HashMap
-impl<K, V> Writeable for HashMap<K, V>
-	where K: Writeable + Eq + Hash,
- V: Writeable
-{
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-	(self.len() as u16).write(w)?;
- for (key, value) in self.iter() {
- key.write(w)?;
- value.write(w)?;
+macro_rules! impl_for_map {
+	($ty: ident, $keybound: ident, $constr: expr) => {
+ impl<K, V> Writeable for $ty<K, V>
+ where K: Writeable + Eq + $keybound, V: Writeable
+ {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for (key, value) in self.iter() {
+ key.write(w)?;
+ value.write(w)?;
+ }
+ Ok(())
+ }
  }
- Ok(())
-	}
-}
 
-impl<K, V> Readable for HashMap<K, V>
-	where K: Readable + Eq + Hash,
- V: MaybeReadable
-{
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashMap::with_capacity(len as usize);
- for _ in 0..len {
- let k = K::read(r)?;
- let v_opt = V::read(r)?;
- if let Some(v) = v_opt {
- if ret.insert(k, v).is_some() {
- return Err(DecodeError::InvalidValue);
+ impl<K, V> Readable for $ty<K, V>
+ where K: Readable + Eq + $keybound, V: MaybeReadable
+ {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = $constr(len.0 as usize);
+ for _ in 0..len.0 {
+ let k = K::read(r)?;
+ let v_opt = V::read(r)?;
+ if let Some(v) = v_opt {
+ if ret.insert(k, v).is_some() {
+ return Err(DecodeError::InvalidValue);
+ }
+ }
  }
+ Ok(ret)
  }
  }
- Ok(ret)
 	}
 }
 
+impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
+impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
+
 // HashSet
 impl<T> Writeable for HashSet<T>
 where T: Writeable + Eq + Hash
 {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  for item in self.iter() {
  item.write(w)?;
  }
@@ -644,9 +684,9 @@ where T: Readable + Eq + Hash
 {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashSet::with_capacity(len as usize);
- for _ in 0..len {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
+ for _ in 0..len.0 {
  if !ret.insert(T::read(r)?) {
  return Err(DecodeError::InvalidValue)
  }
@@ -656,51 +696,62 @@ where T: Readable + Eq + Hash
 }
 
 // Vectors
-impl Writeable for Vec<u8> {
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- w.write_all(&self)
-	}
-}
+macro_rules! impl_for_vec {
+	($ty: ty $(, $name: ident)*) => {
+ impl<$($name : Writeable),*> Writeable for Vec<$ty> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for elem in self.iter() {
+ elem.write(w)?;
+ }
+ Ok(())
+ }
+ }
 
-impl Readable for Vec<u8> {
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = Vec::with_capacity(len as usize);
- ret.resize(len as usize, 0);
- r.read_exact(&mut ret)?;
- Ok(ret)
+ impl<$($name : Readable),*> Readable for Vec<$ty> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
+ for _ in 0..len.0 {
+ if let Some(val) = MaybeReadable::read(r)? {
+ ret.push(val);
+ }
+ }
+ Ok(ret)
+ }
+ }
 	}
 }
-impl Writeable for Vec<ecdsa::Signature> {
+
+impl Writeable for Vec<u8> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- for e in self.iter() {
- e.write(w)?;
- }
- Ok(())
+ CollectionLength(self.len() as u64).write(w)?;
+ w.write_all(&self)
 	}
 }
 
-impl Readable for Vec<ecdsa::Signature> {
+impl Readable for Vec<u8> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let byte_size = (len as usize)
- .checked_mul(COMPACT_SIGNATURE_SIZE)
- .ok_or(DecodeError::BadLengthDescriptor)?;
- if byte_size > MAX_BUF_SIZE {
- return Err(DecodeError::BadLengthDescriptor);
+ let mut len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::new();
+ while len.0 > 0 {
+ let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
+ let readstart = ret.len();
+ ret.resize(readstart + readamt, 0);
+ r.read_exact(&mut ret[readstart..])?;
+ len.0 -= readamt as u64;
  }
- let mut ret = Vec::with_capacity(len as usize);
- for _ in 0..len { ret.push(Readable::read(r)?); }
  Ok(ret)
 	}
 }
 
+impl_for_vec!(ecdsa::Signature);
+impl_for_vec!((A, B), A, B);
+
 impl Writeable for Script {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  (self.len() as u16).write(w)?;
@@ -1028,7 +1079,7 @@ impl Readable for () {
 impl Writeable for String {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  w.write_all(self.as_bytes())
 	}
 }

lightning/src/util/ser_macros.rs

@@ -39,6 +39,9 @@ macro_rules! _encode_tlv {
  field.write($stream)?;
  }
 	};
+	($stream: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_encode_tlv!($stream, $type, $field, required);
+	};
 	($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
  $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
 	};
@@ -155,6 +158,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
  $len.0 += field_len;
  }
 	};
+	($len: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
+	};
 }
 
 /// See the documentation of [`write_tlv_fields`].
@@ -581,6 +587,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
  $field
 	};
+	($field: ident, ignorable) => {
+ if $field.is_none() { return Ok(None); } else { $field.unwrap() }
+	};
 	($field: ident, required) => {
  $field.0.unwrap()
 	};
@@ -610,6 +619,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
  let mut $field = None;
 	};
+	($field: ident, ignorable) => {
+ let mut $field = None;
+	};
 }
 
 /// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].

lightning/src/util/ser.rs

@@ -22,6 +22,8 @@ use core::cmp;
 use core::convert::TryFrom;
 use core::ops::Deref;
 
+use alloc::collections::BTreeMap;
+
 use bitcoin::secp256k1::{PublicKey, SecretKey};
 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
 use bitcoin::secp256k1::ecdsa;
@@ -381,6 +383,40 @@ impl Readable for BigSize {
 	}
 }
 
+/// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
+/// primarily targets that, we must as well. However, because we may serialize objects that have
+/// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
+/// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
+/// "read eight more bytes".
+///
+/// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
+/// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
+/// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
+struct CollectionLength(pub u64);
+impl Writeable for CollectionLength {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+ if self.0 < 0xffff {
+ (self.0 as u16).write(writer)
+ } else {
+ 0xffffu16.write(writer)?;
+ (self.0 - 0xffff).write(writer)
+ }
+	}
+}
+
+impl Readable for CollectionLength {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let mut val: u64 = <u16 as Readable>::read(r)? as u64;
+ if val == 0xffff {
+ val = <u64 as Readable>::read(r)?
+ .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
+ }
+ Ok(CollectionLength(val))
+	}
+}
+
 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
@@ -588,50 +624,54 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
-// HashMap
-impl<K, V> Writeable for HashMap<K, V>
-	where K: Writeable + Eq + Hash,
- V: Writeable
-{
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-	(self.len() as u16).write(w)?;
- for (key, value) in self.iter() {
- key.write(w)?;
- value.write(w)?;
+macro_rules! impl_for_map {
+	($ty: ident, $keybound: ident, $constr: expr) => {
+ impl<K, V> Writeable for $ty<K, V>
+ where K: Writeable + Eq + $keybound, V: Writeable
+ {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for (key, value) in self.iter() {
+ key.write(w)?;
+ value.write(w)?;
+ }
+ Ok(())
+ }
  }
- Ok(())
-	}
-}
 
-impl<K, V> Readable for HashMap<K, V>
-	where K: Readable + Eq + Hash,
- V: MaybeReadable
-{
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashMap::with_capacity(len as usize);
- for _ in 0..len {
- let k = K::read(r)?;
- let v_opt = V::read(r)?;
- if let Some(v) = v_opt {
- if ret.insert(k, v).is_some() {
- return Err(DecodeError::InvalidValue);
+ impl<K, V> Readable for $ty<K, V>
+ where K: Readable + Eq + $keybound, V: MaybeReadable
+ {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = $constr(len.0 as usize);
+ for _ in 0..len.0 {
+ let k = K::read(r)?;
+ let v_opt = V::read(r)?;
+ if let Some(v) = v_opt {
+ if ret.insert(k, v).is_some() {
+ return Err(DecodeError::InvalidValue);
+ }
+ }
  }
+ Ok(ret)
  }
  }
- Ok(ret)
 	}
 }
 
+impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
+impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
+
 // HashSet
 impl<T> Writeable for HashSet<T>
 where T: Writeable + Eq + Hash
 {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  for item in self.iter() {
  item.write(w)?;
  }
@@ -644,9 +684,9 @@ where T: Readable + Eq + Hash
 {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashSet::with_capacity(len as usize);
- for _ in 0..len {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
+ for _ in 0..len.0 {
  if !ret.insert(T::read(r)?) {
  return Err(DecodeError::InvalidValue)
  }
@@ -656,51 +696,62 @@ where T: Readable + Eq + Hash
 }
 
 // Vectors
-impl Writeable for Vec<u8> {
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- w.write_all(&self)
-	}
-}
+macro_rules! impl_for_vec {
+	($ty: ty $(, $name: ident)*) => {
+ impl<$($name : Writeable),*> Writeable for Vec<$ty> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for elem in self.iter() {
+ elem.write(w)?;
+ }
+ Ok(())
+ }
+ }
 
-impl Readable for Vec<u8> {
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = Vec::with_capacity(len as usize);
- ret.resize(len as usize, 0);
- r.read_exact(&mut ret)?;
- Ok(ret)
+ impl<$($name : Readable),*> Readable for Vec<$ty> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
+ for _ in 0..len.0 {
+ if let Some(val) = MaybeReadable::read(r)? {
+ ret.push(val);
+ }
+ }
+ Ok(ret)
+ }
+ }
 	}
 }
-impl Writeable for Vec<ecdsa::Signature> {
+
+impl Writeable for Vec<u8> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- for e in self.iter() {
- e.write(w)?;
- }
- Ok(())
+ CollectionLength(self.len() as u64).write(w)?;
+ w.write_all(&self)
 	}
 }
 
-impl Readable for Vec<ecdsa::Signature> {
+impl Readable for Vec<u8> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let byte_size = (len as usize)
- .checked_mul(COMPACT_SIGNATURE_SIZE)
- .ok_or(DecodeError::BadLengthDescriptor)?;
- if byte_size > MAX_BUF_SIZE {
- return Err(DecodeError::BadLengthDescriptor);
+ let mut len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::new();
+ while len.0 > 0 {
+ let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
+ let readstart = ret.len();
+ ret.resize(readstart + readamt, 0);
+ r.read_exact(&mut ret[readstart..])?;
+ len.0 -= readamt as u64;
  }
- let mut ret = Vec::with_capacity(len as usize);
- for _ in 0..len { ret.push(Readable::read(r)?); }
  Ok(ret)
 	}
 }
 
+impl_for_vec!(ecdsa::Signature);
+impl_for_vec!((A, B), A, B);
+
 impl Writeable for Script {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  (self.len() as u16).write(w)?;
@@ -1028,7 +1079,7 @@ impl Readable for () {
 impl Writeable for String {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  w.write_all(self.as_bytes())
 	}
 }

lightning/src/util/ser_macros.rs

@@ -39,6 +39,9 @@ macro_rules! _encode_tlv {
  field.write($stream)?;
  }
 	};
+	($stream: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_encode_tlv!($stream, $type, $field, required);
+	};
 	($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
  $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
 	};
@@ -155,6 +158,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
  $len.0 += field_len;
  }
 	};
+	($len: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
+	};
 }
 
 /// See the documentation of [`write_tlv_fields`].
@@ -581,6 +587,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
  $field
 	};
+	($field: ident, ignorable) => {
+ if $field.is_none() { return Ok(None); } else { $field.unwrap() }
+	};
 	($field: ident, required) => {
  $field.0.unwrap()
 	};
@@ -610,6 +619,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
  let mut $field = None;
 	};
+	($field: ident, ignorable) => {
+ let mut $field = None;
+	};
 }
 
 /// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].

lightning/src/util/ser.rs

@@ -22,6 +22,8 @@ use core::cmp;
 use core::convert::TryFrom;
 use core::ops::Deref;
 
+use alloc::collections::BTreeMap;
+
 use bitcoin::secp256k1::{PublicKey, SecretKey};
 use bitcoin::secp256k1::constants::{PUBLIC_KEY_SIZE, SECRET_KEY_SIZE, COMPACT_SIGNATURE_SIZE, SCHNORR_SIGNATURE_SIZE};
 use bitcoin::secp256k1::ecdsa;
@@ -381,6 +383,40 @@ impl Readable for BigSize {
 	}
 }
 
+/// The lightning protocol uses u16s for lengths in most cases. As our serialization framework
+/// primarily targets that, we must as well. However, because we may serialize objects that have
+/// more than 65K entries, we need to be able to store larger values. Thus, we define a variable
+/// length integer here that is backwards-compatible for values < 0xffff. We treat 0xffff as
+/// "read eight more bytes".
+///
+/// To ensure we only have one valid encoding per value, we add 0xffff to values written as eight
+/// bytes. Thus, 0xfffe is serialized as 0xfffe, whereas 0xffff is serialized as
+/// 0xffff0000000000000000 (i.e. read-eight-bytes then zero).
+struct CollectionLength(pub u64);
+impl Writeable for CollectionLength {
+	#[inline]
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+ if self.0 < 0xffff {
+ (self.0 as u16).write(writer)
+ } else {
+ 0xffffu16.write(writer)?;
+ (self.0 - 0xffff).write(writer)
+ }
+	}
+}
+
+impl Readable for CollectionLength {
+	#[inline]
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let mut val: u64 = <u16 as Readable>::read(r)? as u64;
+ if val == 0xffff {
+ val = <u64 as Readable>::read(r)?
+ .checked_add(0xffff).ok_or(DecodeError::InvalidValue)?;
+ }
+ Ok(CollectionLength(val))
+	}
+}
+
 /// In TLV we occasionally send fields which only consist of, or potentially end with, a
 /// variable-length integer which is simply truncated by skipping high zero bytes. This type
 /// encapsulates such integers implementing [`Readable`]/[`Writeable`] for them.
@@ -588,50 +624,54 @@ impl<'a, T> From<&'a Vec<T>> for WithoutLength<&'a Vec<T>> {
 	fn from(v: &'a Vec<T>) -> Self { Self(v) }
 }
 
-// HashMap
-impl<K, V> Writeable for HashMap<K, V>
-	where K: Writeable + Eq + Hash,
- V: Writeable
-{
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-	(self.len() as u16).write(w)?;
- for (key, value) in self.iter() {
- key.write(w)?;
- value.write(w)?;
+macro_rules! impl_for_map {
+	($ty: ident, $keybound: ident, $constr: expr) => {
+ impl<K, V> Writeable for $ty<K, V>
+ where K: Writeable + Eq + $keybound, V: Writeable
+ {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for (key, value) in self.iter() {
+ key.write(w)?;
+ value.write(w)?;
+ }
+ Ok(())
+ }
  }
- Ok(())
-	}
-}
 
-impl<K, V> Readable for HashMap<K, V>
-	where K: Readable + Eq + Hash,
- V: MaybeReadable
-{
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashMap::with_capacity(len as usize);
- for _ in 0..len {
- let k = K::read(r)?;
- let v_opt = V::read(r)?;
- if let Some(v) = v_opt {
- if ret.insert(k, v).is_some() {
- return Err(DecodeError::InvalidValue);
+ impl<K, V> Readable for $ty<K, V>
+ where K: Readable + Eq + $keybound, V: MaybeReadable
+ {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = $constr(len.0 as usize);
+ for _ in 0..len.0 {
+ let k = K::read(r)?;
+ let v_opt = V::read(r)?;
+ if let Some(v) = v_opt {
+ if ret.insert(k, v).is_some() {
+ return Err(DecodeError::InvalidValue);
+ }
+ }
  }
+ Ok(ret)
  }
  }
- Ok(ret)
 	}
 }
 
+impl_for_map!(BTreeMap, Ord, |_| BTreeMap::new());
+impl_for_map!(HashMap, Hash, |len| HashMap::with_capacity(len));
+
 // HashSet
 impl<T> Writeable for HashSet<T>
 where T: Writeable + Eq + Hash
 {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  for item in self.iter() {
  item.write(w)?;
  }
@@ -644,9 +684,9 @@ where T: Readable + Eq + Hash
 {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = HashSet::with_capacity(len as usize);
- for _ in 0..len {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = HashSet::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<T>()));
+ for _ in 0..len.0 {
  if !ret.insert(T::read(r)?) {
  return Err(DecodeError::InvalidValue)
  }
@@ -656,51 +696,62 @@ where T: Readable + Eq + Hash
 }
 
 // Vectors
-impl Writeable for Vec<u8> {
-	#[inline]
-	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- w.write_all(&self)
-	}
-}
+macro_rules! impl_for_vec {
+	($ty: ty $(, $name: ident)*) => {
+ impl<$($name : Writeable),*> Writeable for Vec<$ty> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ CollectionLength(self.len() as u64).write(w)?;
+ for elem in self.iter() {
+ elem.write(w)?;
+ }
+ Ok(())
+ }
+ }
 
-impl Readable for Vec<u8> {
-	#[inline]
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let mut ret = Vec::with_capacity(len as usize);
- ret.resize(len as usize, 0);
- r.read_exact(&mut ret)?;
- Ok(ret)
+ impl<$($name : Readable),*> Readable for Vec<$ty> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::with_capacity(cmp::min(len.0 as usize, MAX_BUF_SIZE / core::mem::size_of::<$ty>()));
+ for _ in 0..len.0 {
+ if let Some(val) = MaybeReadable::read(r)? {
+ ret.push(val);
+ }
+ }
+ Ok(ret)
+ }
+ }
 	}
 }
-impl Writeable for Vec<ecdsa::Signature> {
+
+impl Writeable for Vec<u8> {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
- for e in self.iter() {
- e.write(w)?;
- }
- Ok(())
+ CollectionLength(self.len() as u64).write(w)?;
+ w.write_all(&self)
 	}
 }
 
-impl Readable for Vec<ecdsa::Signature> {
+impl Readable for Vec<u8> {
 	#[inline]
 	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let len: u16 = Readable::read(r)?;
- let byte_size = (len as usize)
- .checked_mul(COMPACT_SIGNATURE_SIZE)
- .ok_or(DecodeError::BadLengthDescriptor)?;
- if byte_size > MAX_BUF_SIZE {
- return Err(DecodeError::BadLengthDescriptor);
+ let mut len: CollectionLength = Readable::read(r)?;
+ let mut ret = Vec::new();
+ while len.0 > 0 {
+ let readamt = cmp::min(len.0 as usize, MAX_BUF_SIZE);
+ let readstart = ret.len();
+ ret.resize(readstart + readamt, 0);
+ r.read_exact(&mut ret[readstart..])?;
+ len.0 -= readamt as u64;
  }
- let mut ret = Vec::with_capacity(len as usize);
- for _ in 0..len { ret.push(Readable::read(r)?); }
  Ok(ret)
 	}
 }
 
+impl_for_vec!(ecdsa::Signature);
+impl_for_vec!((A, B), A, B);
+
 impl Writeable for Script {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  (self.len() as u16).write(w)?;
@@ -1028,7 +1079,7 @@ impl Readable for () {
 impl Writeable for String {
 	#[inline]
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- (self.len() as u16).write(w)?;
+CollectionLength(self.len() as u64).write(w)?;
  w.write_all(self.as_bytes())
 	}
 }

lightning/src/util/ser_macros.rs

@@ -39,6 +39,9 @@ macro_rules! _encode_tlv {
  field.write($stream)?;
  }
 	};
+	($stream: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_encode_tlv!($stream, $type, $field, required);
+	};
 	($stream: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
  $crate::_encode_tlv!($stream, $type, $field.map(|f| $encoding(f)), option);
 	};
@@ -155,6 +158,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
  $len.0 += field_len;
  }
 	};
+	($len: expr, $type: expr, $field: expr, ignorable) => {
+ $crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
+	};
 }
 
 /// See the documentation of [`write_tlv_fields`].
@@ -581,6 +587,9 @@ macro_rules! _init_tlv_based_struct_field {
 	($field: ident, option) => {
  $field
 	};
+	($field: ident, ignorable) => {
+ if $field.is_none() { return Ok(None); } else { $field.unwrap() }
+	};
 	($field: ident, required) => {
  $field.0.unwrap()
 	};
@@ -610,6 +619,9 @@ macro_rules! _init_tlv_field_var {
 	($field: ident, option) => {
  let mut $field = None;
 	};
+	($field: ident, ignorable) => {
+ let mut $field = None;
+	};
 }
 
 /// Equivalent to running [`_init_tlv_field_var`] then [`read_tlv_fields`].