Previously, we were decoding payload lengths as a VarInt. Per the spec, this is
wrong -- it should be decoded as a BigSize. This bug also exists in our
payment payload decoding, to be fixed separately.
Upcoming reply path tests caught this bug because we hadn't encoded a payload
greater than 253 before, so we hadn't hit the problem that VarInts are encoded
as little-endian whereas BigSizes are encoded as big-endian.
This required adapting `onion_utils::decode_next_hop` to work for both payments
and onion messages.
Currently we just print out the path_id of any onion messages we receive. In
the future, these received onion messages will be redirected to their
respective handlers: i.e. an invoice_request will go to an InvoiceHandler,
custom onion messages will go to a custom handler, etc.
This adds several utilities in service of then adding
OnionMessenger::send_onion_message, which can send to either an unblinded
pubkey or a blinded route. Sending custom TLVs and sending an onion message
containing a reply path are not yet supported.
We also need to split the construct_keys_callback macro into two macros to
avoid an unused assignment warning.
We need to add a new Packet struct because onion message packet hop_data fields
can be of variable length, whereas regular payment packets are always 1366
bytes.
Co-authored-by: Valentine Wallace <vwallace@protonmail.com>
Co-authored-by: Jeffrey Czyz <jkczyz@gmail.com>
