_ Git - rust-lightning/blob - lightning/src/onion_message/packet.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! Structs and enums useful for constructing and reading an onion message packet.
  11
  12 use bitcoin::secp256k1::PublicKey;
  13
  14 use ln::msgs::DecodeError;
  15 use ln::onion_utils;
  16 use super::blinded_route::{ForwardTlvs, ReceiveTlvs};
  17 use util::chacha20poly1305rfc::ChaChaPolyWriteAdapter;
  18 use util::ser::{LengthRead, LengthReadable, Readable, Writeable, Writer};
  19
  20 use core::cmp;
  21 use io;
  22 use prelude::*;
  23
  24 // Per the spec, an onion message packet's `hop_data` field length should be
  25 // SMALL_PACKET_HOP_DATA_LEN if it fits, else BIG_PACKET_HOP_DATA_LEN if it fits.
  26 pub(super) const SMALL_PACKET_HOP_DATA_LEN: usize = 1300;
  27 pub(super) const BIG_PACKET_HOP_DATA_LEN: usize = 32768;
  28
  29 #[derive(Clone, Debug, PartialEq)]
  30 pub(crate) struct Packet {
  31         version: u8,
  32         public_key: PublicKey,
  33         // Unlike the onion packets used for payments, onion message packets can have payloads greater
  34         // than 1300 bytes.
  35         // TODO: if 1300 ends up being the most common size, optimize this to be:
  36         // enum { ThirteenHundred([u8; 1300]), VarLen(Vec<u8>) }
  37         hop_data: Vec<u8>,
  38         hmac: [u8; 32],
  39 }
  40
  41 impl onion_utils::Packet for Packet {
  42         type Data = Vec<u8>;
  43         fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Packet {
  44                 Self {
  45                         version: 0,
  46                         public_key,
  47                         hop_data,
  48                         hmac,
  49                 }
  50         }
  51 }
  52
  53 impl Writeable for Packet {
  54         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  55                 self.version.write(w)?;
  56                 self.public_key.write(w)?;
  57                 w.write_all(&self.hop_data)?;
  58                 self.hmac.write(w)?;
  59                 Ok(())
  60         }
  61 }
  62
  63 impl LengthReadable for Packet {
  64         fn read<R: LengthRead>(r: &mut R) -> Result<Self, DecodeError> {
  65                 const READ_BUFFER_SIZE: usize = 4096;
  66
  67                 let version = Readable::read(r)?;
  68                 let public_key = Readable::read(r)?;
  69
  70                 let mut hop_data = Vec::new();
  71                 let hop_data_len = r.total_bytes() as usize - 66; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
  72                 let mut read_idx = 0;
  73                 while read_idx < hop_data_len {
  74                         let mut read_buffer = [0; READ_BUFFER_SIZE];
  75                         let read_amt = cmp::min(hop_data_len - read_idx, READ_BUFFER_SIZE);
  76                         r.read_exact(&mut read_buffer[..read_amt]);
  77                         hop_data.extend_from_slice(&read_buffer[..read_amt]);
  78                         read_idx += read_amt;
  79                 }
  80
  81                 let hmac = Readable::read(r)?;
  82                 Ok(Packet {
  83                         version,
  84                         public_key,
  85                         hop_data,
  86                         hmac,
  87                 })
  88         }
  89 }
  90
  91 /// Onion message payloads contain "control" TLVs and "data" TLVs. Control TLVs are used to route
  92 /// the onion message from hop to hop and for path verification, whereas data TLVs contain the onion
  93 /// message content itself, such as an invoice request.
  94 pub(super) enum Payload {
  95         /// This payload is for an intermediate hop.
  96         Forward(ForwardControlTlvs),
  97         /// This payload is for the final hop.
  98         Receive {
  99                 control_tlvs: ReceiveControlTlvs,
 100                 // Coming soon:
 101                 // reply_path: Option<BlindedRoute>,
 102                 // message: Message,
 103         }
 104 }
 105
 106 // Coming soon:
 107 // enum Message {
 108 //      InvoiceRequest(InvoiceRequest),
 109 //      Invoice(Invoice),
 110 //      InvoiceError(InvoiceError),
 111 //      CustomMessage<T>,
 112 // }
 113
 114 /// Forward control TLVs in their blinded and unblinded form.
 115 pub(super) enum ForwardControlTlvs {
 116         /// If we're sending to a blinded route, the node that constructed the blinded route has provided
 117         /// this hop's control TLVs, already encrypted into bytes.
 118         Blinded(Vec<u8>),
 119         /// If we're constructing an onion message hop through an intermediate unblinded node, we'll need
 120         /// to construct the intermediate hop's control TLVs in their unblinded state to avoid encoding
 121         /// them into an intermediate Vec. See [`super::blinded_route::ForwardTlvs`] for more info.
 122         Unblinded(ForwardTlvs),
 123 }
 124
 125 /// Receive control TLVs in their blinded and unblinded form.
 126 pub(super) enum ReceiveControlTlvs {
 127         /// See [`ForwardControlTlvs::Blinded`].
 128         Blinded(Vec<u8>),
 129         /// See [`ForwardControlTlvs::Unblinded`] and [`super::blinded_route::ReceiveTlvs`].
 130         Unblinded(ReceiveTlvs),
 131 }
 132
 133 // Uses the provided secret to simultaneously encode and encrypt the unblinded control TLVs.
 134 impl Writeable for (Payload, [u8; 32]) {
 135         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 136                 match &self.0 {
 137                         Payload::Forward(ForwardControlTlvs::Blinded(encrypted_bytes)) |
 138                         Payload::Receive { control_tlvs: ReceiveControlTlvs::Blinded(encrypted_bytes)} => {
 139                                 encode_varint_length_prefixed_tlv!(w, {
 140                                         (4, encrypted_bytes, vec_type)
 141                                 })
 142                         },
 143                         Payload::Forward(ForwardControlTlvs::Unblinded(control_tlvs)) => {
 144                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 145                                 encode_varint_length_prefixed_tlv!(w, {
 146                                         (4, write_adapter, required)
 147                                 })
 148                         },
 149                         Payload::Receive { control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs)} => {
 150                                 let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 151                                 encode_varint_length_prefixed_tlv!(w, {
 152                                         (4, write_adapter, required)
 153                                 })
 154                         },
 155                 }
 156                 Ok(())
 157         }
 158 }