X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fonion_message%2Fpacket.rs;h=a3414d844edff9cb96f5d6b15cf36e5807b29d9a;hb=28c9b56113ff1ebb1b505a2c979c55c1626aa06b;hp=37f178f5521ccfcc6f5f26738f949bc69945872b;hpb=33ff2746ef3d1a36aab4f07cd1a7b512b6e411da;p=rust-lightning diff --git a/lightning/src/onion_message/packet.rs b/lightning/src/onion_message/packet.rs index 37f178f5..a3414d84 100644 --- a/lightning/src/onion_message/packet.rs +++ b/lightning/src/onion_message/packet.rs @@ -10,25 +10,33 @@ //! 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::{ForwardTlvs, ReceiveTlvs}; +use util::chacha20poly1305rfc::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter}; +use util::ser::{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) } - hop_data: Vec, - hmac: [u8; 32], + pub(super) hop_data: Vec, + pub(super) hmac: [u8; 32], } impl onion_utils::Packet for Packet { @@ -80,3 +88,163 @@ impl LengthReadable for Packet { }) } } + +/// 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, + // Coming soon: + // reply_path: Option, + // message: Message, + } +} + +// Coming soon: +// enum Message { +// InvoiceRequest(InvoiceRequest), +// Invoice(Invoice), +// InvoiceError(InvoiceError), +// CustomMessage, +// } + +/// 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), + /// 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), + /// 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(&self, w: &mut W) -> Result<(), io::Error> { + match &self.0 { + Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) | + Payload::Receive { control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes)} => { + encode_varint_length_prefixed_tlv!(w, { + (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)} => { + let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs); + encode_varint_length_prefixed_tlv!(w, { + (4, write_adapter, required) + }) + }, + } + Ok(()) + } +} + +// Uses the provided secret to simultaneously decode and decrypt the control TLVs. +impl ReadableArgs for Payload { + fn read(mut r: &mut R, encrypted_tlvs_ss: SharedSecret) -> Result { + use bitcoin::consensus::encode::{Decodable, Error, VarInt}; + let v: VarInt = Decodable::consensus_decode(&mut r) + .map_err(|e| match e { + Error::Io(ioe) => DecodeError::from(ioe), + _ => DecodeError::InvalidValue + })?; + + let mut rd = FixedLengthReader::new(r, v.0); + // TODO: support reply paths + let mut _reply_path_bytes: Option> = Some(Vec::new()); + let mut read_adapter: Option> = None; + let rho = onion_utils::gen_rho_from_shared_secret(&encrypted_tlvs_ss.secret_bytes()); + decode_tlv_stream!(&mut rd, { + (2, _reply_path_bytes, vec_type), + (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)}) + }, + } + } +} + +/// 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(mut r: &mut R) -> Result { + let mut _padding: Option = None; + let mut _short_channel_id: Option = None; + let mut next_node_id: Option = None; + let mut path_id: Option<[u8; 32]> = None; + let mut next_blinding_override: Option = 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(reader: &mut R) -> Result { + loop { + let mut buf = [0; 8192]; + if reader.read(&mut buf[..])? == 0 { break; } + } + Ok(Self {}) + } +}