When we introduce blinded routes, some of our hops are expected
to have zero amounts to forward in their hop payload. This commit
updates our hop fee logic to attribute the full blinded route's
fees to the introduction node. We can't actually know where/how
these fees are distributed, so we collect them all at the
introduction node.
With the addition of blinded routes, we now need to account for the
possibility that intermediate nodes payloads will not have an amount
and expiry set because that information is provided by the recipient
encrypted data blob. This commit updates our payload packing to only
optionally include those fields.
This commit adds the encrypted_data, blinding_point and total_amt_msat
tlvs to the known set of even tlvs for the onion payload. These TLVs
are added in two places (the onion payload and hop struct) because
lnd uses the same set of TLV types for both structs (and they
inherently represent the same thing).
Note: in some places, unit tests intentionally mimic the style
of older tests, so as to be more consistently readable.
This commit was previously split into the following parts to ease
review:
- 2d746f68: replace imports
- 4008f0fd: use ecdsa.Signature
- 849e33d1: remove btcec.S256()
- b8f6ebbd: use v2 library correctly
- fa80bca9: bump go modules
