Introduce TrampolineOnionPacket.

diff --git a/lightning/src/ln/msgs.rs b/lightning/src/ln/msgs.rs
index d291ac8664aceec5fdaff3b0d2ce20077e727028..cf569f4c493908ae0b29eb353d5d71401555804a 100644 (file)
--- a/lightning/src/ln/msgs.rs
+++ b/lightning/src/ln/msgs.rs
@@ -1765,6 +1765,52 @@ impl fmt::Debug for OnionPacket {
        }
 }
 
+/// BOLT 4 onion packet including hop data for the next peer.
+#[derive(Clone, Hash, PartialEq, Eq)]
+pub struct TrampolineOnionPacket {
+       /// Bolt 04 version number
+       pub version: u8,
+       /// A random sepc256k1 point, used to build the ECDH shared secret to decrypt hop_data
+       pub public_key: PublicKey,
+       /// Encrypted payload for the next hop
+       //
+       // Unlike the onion packets used for payments, Trampoline onion packets have to be shorter than
+       // 1300 bytes. The expected default is 650 bytes.
+       // TODO: if 650 ends up being the most common size, optimize this to be:
+       // enum { ThirteenHundred([u8; 650]), VarLen(Vec<u8>) }
+       pub hop_data: Vec<u8>,
+       /// HMAC to verify the integrity of hop_data
+       pub hmac: [u8; 32],
+}
+
+impl onion_utils::Packet for TrampolineOnionPacket {
+       type Data = Vec<u8>;
+       fn new(public_key: PublicKey, hop_data: Vec<u8>, hmac: [u8; 32]) -> Self {
+               Self {
+                       version: 0,
+                       public_key,
+                       hop_data,
+                       hmac,
+               }
+       }
+}
+
+impl Writeable for TrampolineOnionPacket {
+       fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+               self.version.write(w)?;
+               self.public_key.write(w)?;
+               w.write_all(&self.hop_data)?;
+               self.hmac.write(w)?;
+               Ok(())
+       }
+}
+
+impl Debug for TrampolineOnionPacket {
+       fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+               f.write_fmt(format_args!("TrampolineOnionPacket version {} with hmac {:?}", self.version, &self.hmac[..]))
+       }
+}
+
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub(crate) struct OnionErrorPacket {
        // This really should be a constant size slice, but the spec lets these things be up to 128KB?