In this commit we bump the minimum LND version required to run loopd to
v0.15.1-beta in order to ensure that the underlying chain backend
supports taproot (https://github.com/lightningnetwork/lnd/pull/6798)
In this commit we deprecate the sighash field from the
MuSig2SignSweepReq request in favour of using a psbt serialized sweep
transaction instead. This way the sever gains full transparency about
client sweep requests and can assemble the sighash to sign on its own.
This commit adds optional cooperative musig2 sweep by calling the server
to create a partial signature for the sweep if we'd otherwise be allowed
to spend the htlc. If the cooperative musig2 spend fails, we always fall
back to use the scriptpath spend.
This commit moves the RequiredPermissions map to its own directory so
that projects importing the permissions list dont need to import all the
dependencies of the loopd package.
Taproot spends require a different sighash, so we update our HtlcScript
interface to provide the appropriate sighash when sweeping. We also add
distinct Timeout/Success Script functions to allow for tapleaf spends
which have different locking scripts for different paths. Note that the
timeout and success paths will be the same for segwit v0 htlcs, because
it has a single branched script containing all spend paths.
In future iterations, this differentiation of claim scripts can also
be used to use musig2 to collaboratively keyspend P2TR htlcs with the
server. This script can be expressed as PriorityScript (because we'll
try to keyspend as a priority, and then fall back to a tap leaf spend).
As we've done here, segwit v0 spends would just return their single
script for PriorityScript, and the claim would be no different from
our other claims.
Use of the Script() function is problematic when we introduce taproot
because our script will vary depending whether we use keyspend or a
tapleaf spend path (and on the tapleaf spent). This has not previously
been a problem for segwitv0 scripts, because they contain all of the
logical branches for each of our spend conditions in a single script.
This commit prepares for removal of the Script() function by moving
our address/pkScript/sigScript generation (which need Script()) into
each script's implementation of the HtlcScript interface so that
they have access to the script directly.
This commit saves the RPC request used to construct the `Parameters` on
disk. Since it's a proto message, an easy way to read/write it is to
rely on the proto marshal/unmarshal methods. A side effect is that
migration also becomes easy as proto message have its own internal
mechanism to keep track of the compatibility.
