//! Structs and enums useful for constructing and reading an onion message packet.
use bitcoin::secp256k1::PublicKey;
+use bitcoin::secp256k1::ecdh::SharedSecret;
use ln::msgs::DecodeError;
use ln::onion_utils;
-use util::ser::{LengthRead, LengthReadable, Readable, Writeable, Writer};
+use super::blinded_route::{BlindedRoute, ForwardTlvs, ReceiveTlvs};
+use util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
+use util::ser::{BigSize, FixedLengthReader, LengthRead, LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer};
use core::cmp;
-use io;
+use io::{self, Read};
use prelude::*;
+// Per the spec, an onion message packet's `hop_data` field length should be
+// SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
+pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
+pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
+
#[derive(Clone, Debug, PartialEq)]
pub(crate) struct Packet {
- version: u8,
- public_key: PublicKey,
+ pub(super) version: u8,
+ pub(super) public_key: PublicKey,
// Unlike the onion packets used for payments, onion message packets can have payloads greater
// than 1300 bytes.
// TODO: if 1300 ends up being the most common size, optimize this to be:
// enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
- hop_data: Vec<u8>,
- hmac: [u8; 32],
+ pub(super) hop_data: Vec<u8>,
+ pub(super) hmac: [u8; 32],
}
impl onion_utils::Packet for Packet {
let public_key = Readable::read(r)?;
let mut hop_data = Vec::new();
- let hop_data_len = r.total_bytes() as usize - 66; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
+ let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
let mut read_idx = 0;
while read_idx < hop_data_len {
let mut read_buffer = [0; READ_BUFFER_SIZE];
let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
- r.read_exact(&mut read_buffer[..read_amt]);
+ r.read_exact(&mut read_buffer[..read_amt])?;
hop_data.extend_from_slice(&read_buffer[..read_amt]);
read_idx += read_amt;
}
})
}
}
+
+/// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
+/// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
+/// message content itself, such as an invoice request.
+pub(super) enum Payload {
+ /// This payload is for an intermediate hop.
+ Forward(ForwardControlTlvs),
+ /// This payload is for the final hop.
+ Receive {
+ control_tlvs: ReceiveControlTlvs,
+ reply_path: Option<BlindedRoute>,
+ // Coming soon:
+ // message: Message,
+ }
+}
+
+// Coming soon:
+// enum Message {
+// InvoiceRequest(InvoiceRequest),
+// Invoice(Invoice),
+// InvoiceError(InvoiceError),
+// CustomMessage<T>,
+// }
+
+/// Forward control TLVs in their blinded and unblinded form.
+pub(super) enum ForwardControlTlvs {
+ /// If we're sending to a blinded route, the node that constructed the blinded route has provided
+ /// this hop's control TLVs, already encrypted into bytes.
+ Blinded(Vec<u8>),
+ /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
+ /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
+ /// them into an intermediate Vec. See [`super::blinded_route::ForwardTlvs`] for more info.
+ Unblinded(ForwardTlvs),
+}
+
+/// Receive control TLVs in their blinded and unblinded form.
+pub(super) enum ReceiveControlTlvs {
+ /// See [`ForwardControlTlvs::Blinded`].
+ Blinded(Vec<u8>),
+ /// See [`ForwardControlTlvs::Unblinded`] and [`super::blinded_route::ReceiveTlvs`].
+ Unblinded(ReceiveTlvs),
+}
+
+// Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
+impl Writeable for (Payload, [u8; 32]) {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ match &self.0 {
+ Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) => {
+ encode_varint_length_prefixed_tlv!(w, {
+ (4, encrypted_bytes, vec_type)
+ })
+ },
+ Payload::Receive {
+ control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes), reply_path
+ } => {
+ encode_varint_length_prefixed_tlv!(w, {
+ (2, reply_path, option),
+ (4, encrypted_bytes, vec_type)
+ })
+ },
+ Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
+ let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
+ encode_varint_length_prefixed_tlv!(w, {
+ (4, write_adapter, required)
+ })
+ },
+ Payload::Receive {
+ control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs), reply_path,
+ } => {
+ let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
+ encode_varint_length_prefixed_tlv!(w, {
+ (2, reply_path, option),
+ (4, write_adapter, required)
+ })
+ },
+ }
+ Ok(())
+ }
+}
+
+// Uses the provided secret to simultaneously decode and decrypt the control TLVs.
+impl ReadableArgs<SharedSecret> for Payload {
+ fn read<R: Read>(r: &mut R, encrypted_tlvs_ss: SharedSecret) -> Result<Self, DecodeError> {
+ let v: BigSize = Readable::read(r)?;
+ let mut rd = FixedLengthReader::new(r, v.0);
+ let mut reply_path: Option<BlindedRoute> = None;
+ let mut read_adapter: Option<ChaChaPolyReadAdapter<ControlTlvs>> = None;
+ let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes());
+ decode_tlv_stream!(&mut rd, {
+ (2, reply_path, option),
+ (4, read_adapter, (option: LengthReadableArgs, rho))
+ });
+ rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
+
+ match read_adapter {
+ None => return Err(DecodeError::InvalidValue),
+ Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Forward(tlvs)}) => {
+ Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
+ },
+ Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs)}) => {
+ Ok(Payload::Receive { control_tlvs: ReceiveControlTlvs::Unblinded(tlvs), reply_path })
+ },
+ }
+ }
+}
+
+/// When reading a packet off the wire, we don't know a priori whether the packet is to be forwarded
+/// or received. Thus we read a ControlTlvs rather than reading a ForwardControlTlvs or
+/// ReceiveControlTlvs directly.
+pub(super) enum ControlTlvs {
+ /// This onion message is intended to be forwarded.
+ Forward(ForwardTlvs),
+ /// This onion message is intended to be received.
+ Receive(ReceiveTlvs),
+}
+
+impl Readable for ControlTlvs {
+ fn read<R: Read>(mut r: &mut R) -> Result<Self, DecodeError> {
+ let mut _padding: Option<Padding> = None;
+ let mut _short_channel_id: Option<u64> = None;
+ let mut next_node_id: Option<PublicKey> = None;
+ let mut path_id: Option<[u8; 32]> = None;
+ let mut next_blinding_override: Option<PublicKey> = None;
+ decode_tlv_stream!(&mut r, {
+ (1, _padding, option),
+ (2, _short_channel_id, option),
+ (4, next_node_id, option),
+ (6, path_id, option),
+ (8, next_blinding_override, option),
+ });
+
+ let valid_fwd_fmt = next_node_id.is_some() && path_id.is_none();
+ let valid_recv_fmt = next_node_id.is_none() && next_blinding_override.is_none();
+
+ let payload_fmt = if valid_fwd_fmt {
+ ControlTlvs::Forward(ForwardTlvs {
+ next_node_id: next_node_id.unwrap(),
+ next_blinding_override,
+ })
+ } else if valid_recv_fmt {
+ ControlTlvs::Receive(ReceiveTlvs {
+ path_id,
+ })
+ } else {
+ return Err(DecodeError::InvalidValue)
+ };
+
+ Ok(payload_fmt)
+ }
+}
+
+/// Reads padding to the end, ignoring what's read.
+pub(crate) struct Padding {}
+impl Readable for Padding {
+ #[inline]
+ fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
+ loop {
+ let mut buf = [0; 8192];
+ if reader.read(&mut buf[..])? == 0 { break; }
+ }
+ Ok(Self {})
+ }
+}
projects / rust-lightning / blobdiff