Use LengthReadable for remaining read-to-end Readables

See previous commits. When deserializing these structs, they will consume the
reader until it is out of bytes. Therefore, it's safer if they are only
provided with readers that limit how much of the byte stream will be read.

lightning/src/ln/msgs.rs

@@ -2094,8 +2094,8 @@ impl Writeable for AcceptChannel {
 	}
 }
 
-impl Readable for AcceptChannel {
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+impl LengthReadable for AcceptChannel {
+	fn read_from_fixed_length_buffer<'a, R: Read>(r: &mut FixedLengthReader<'a, R>) -> Result<Self, DecodeError> {
 		let temporary_channel_id: ChannelId = Readable::read(r)?;
 		let dust_limit_satoshis: u64 = Readable::read(r)?;
 		let max_htlc_value_in_flight_msat: u64 = Readable::read(r)?;
@@ -2179,8 +2179,8 @@ impl Writeable for AcceptChannelV2 {
 	}
 }
 
-impl Readable for AcceptChannelV2 {
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+impl LengthReadable for AcceptChannelV2 {
+	fn read_from_fixed_length_buffer<'a, R: Read>(r: &mut FixedLengthReader<'a, R>) -> Result<Self, DecodeError> {
 		let temporary_channel_id: ChannelId = Readable::read(r)?;
 		let funding_satoshis: u64 = Readable::read(r)?;
 		let dust_limit_satoshis: u64 = Readable::read(r)?;
@@ -2442,8 +2442,8 @@ impl Writeable for Init {
 	}
 }
 
-impl Readable for Init {
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+impl LengthReadable for Init {
+	fn read_from_fixed_length_buffer<'a, R: Read>(r: &mut FixedLengthReader<'a, R>) -> Result<Self, DecodeError> {
 		let global_features: InitFeatures = Readable::read(r)?;
 		let features: InitFeatures = Readable::read(r)?;
 		let mut remote_network_address: Option<SocketAddress> = None;
@@ -2488,8 +2488,8 @@ impl Writeable for OpenChannel {
 	}
 }
 
-impl Readable for OpenChannel {
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+impl LengthReadable for OpenChannel {
+	fn read_from_fixed_length_buffer<'a, R: Read>(r: &mut FixedLengthReader<'a, R>) -> Result<Self, DecodeError> {
 		let chain_hash: ChainHash = Readable::read(r)?;
 		let temporary_channel_id: ChannelId = Readable::read(r)?;
 		let funding_satoshis: u64 = Readable::read(r)?;
@@ -2572,8 +2572,8 @@ impl Writeable for OpenChannelV2 {
 	}
 }
 
-impl Readable for OpenChannelV2 {
-	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+impl LengthReadable for OpenChannelV2 {
+	fn read_from_fixed_length_buffer<'a, R: Read>(r: &mut FixedLengthReader<'a, R>) -> Result<Self, DecodeError> {
 		let chain_hash: ChainHash = Readable::read(r)?;
 		let temporary_channel_id: ChannelId = Readable::read(r)?;
 		let funding_feerate_sat_per_1000_weight: u32 = Readable::read(r)?;

lightning/src/ln/wire.rs

@@ -257,7 +257,9 @@ where
 	H::Target: CustomMessageReader<CustomMessage = T>,
 {
 	match message_type {
-		msgs::Init::TYPE => Ok(Message::Init(Readable::read(buffer)?)),
+		msgs::Init::TYPE => {
+			Ok(Message::Init(LengthReadable::read_from_fixed_length_buffer(buffer)?))
+		},
 		msgs::ErrorMessage::TYPE => Ok(Message::Error(Readable::read(buffer)?)),
 		msgs::WarningMessage::TYPE => Ok(Message::Warning(Readable::read(buffer)?)),
 		msgs::Ping::TYPE => Ok(Message::Ping(Readable::read(buffer)?)),
@@ -268,10 +270,18 @@ where
 		msgs::PeerStorageRetrieval::TYPE => Ok(Message::PeerStorageRetrieval(
 			LengthReadable::read_from_fixed_length_buffer(buffer)?,
 		)),
-		msgs::OpenChannel::TYPE => Ok(Message::OpenChannel(Readable::read(buffer)?)),
-		msgs::OpenChannelV2::TYPE => Ok(Message::OpenChannelV2(Readable::read(buffer)?)),
-		msgs::AcceptChannel::TYPE => Ok(Message::AcceptChannel(Readable::read(buffer)?)),
-		msgs::AcceptChannelV2::TYPE => Ok(Message::AcceptChannelV2(Readable::read(buffer)?)),
+		msgs::OpenChannel::TYPE => {
+			Ok(Message::OpenChannel(LengthReadable::read_from_fixed_length_buffer(buffer)?))
+		},
+		msgs::OpenChannelV2::TYPE => {
+			Ok(Message::OpenChannelV2(LengthReadable::read_from_fixed_length_buffer(buffer)?))
+		},
+		msgs::AcceptChannel::TYPE => {
+			Ok(Message::AcceptChannel(LengthReadable::read_from_fixed_length_buffer(buffer)?))
+		},
+		msgs::AcceptChannelV2::TYPE => {
+			Ok(Message::AcceptChannelV2(LengthReadable::read_from_fixed_length_buffer(buffer)?))
+		},
 		msgs::FundingCreated::TYPE => {
 			Ok(Message::FundingCreated(LengthReadable::read_from_fixed_length_buffer(buffer)?))
 		},

lightning/src/offers/offer.rs

@@ -88,7 +88,8 @@ use crate::offers::parse::{Bech32Encode, Bolt12ParseError, Bolt12SemanticError,
 use crate::offers::signer::{self, Metadata, MetadataMaterial};
 use crate::types::features::OfferFeatures;
 use crate::util::ser::{
-	CursorReadable, HighZeroBytesDroppedBigSize, Readable, WithoutLength, Writeable, Writer,
+	CursorReadable, FixedLengthReader, HighZeroBytesDroppedBigSize, LengthReadable, Readable,
+	WithoutLength, Writeable, Writer,
 };
 use crate::util::string::PrintableString;
 use bitcoin::constants::ChainHash;
@@ -1033,8 +1034,10 @@ impl OfferContents {
 	}
 }
 
-impl Readable for Offer {
-	fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+impl LengthReadable for Offer {
+	fn read_from_fixed_length_buffer<'a, R: io::Read>(
+		reader: &mut FixedLengthReader<'a, R>,
+	) -> Result<Self, DecodeError> {
 		let bytes: WithoutLength<Vec<u8>> = Readable::read(reader)?;
 		Self::try_from(bytes.0).map_err(|_| DecodeError::InvalidValue)
 	}