Because we don't have an HTLCState for
update_add_htlc-generated-but-not-yet-commitment_signed to simplify
the mess of HTLCState match arms, any time a Channel::send_htlc
call returns Ok(Some(_)) we MUST call commitment_signed and it MUST
return success (or close the channel). We mention this in the docs
and panic if its not met in ChannelManager (which lets the fuzz
tester check this).
Because we've separated out channel closure from ErrorMessage
returning we can return error messages in a few additional cases,
like if the peer sent us a message for a channel they didn't own.
This resolves a spec-compliance bug with BOLT 4 where we simply
failed to deserialize the message and thus could never return an
HTLC failure message. However, note that BOLT 4 incorrectly hints
that a non-malformed message should be used ("...MUST report a
route failure to the origin node") which we cannot do as we cannot
derive a SharedSecret to encrypt a regular update_fail_htlc message
UpdateFailHTLC isn't really an error anymore now that its handled
async after channel commitment (as required by BOLT 2), and since
its unused this is free. To resolve the TODO which intended to use
it for HTLC failure when trying to route forwards, we instead opt
to merge all the HTLC update events into one UpdateHTLCs event
which just contains a CommitmentUpdate object.
This fixes a violation of BOLT 2 and will let us consolidate some
HTLC update handling. Good bit of code movement, but is mostly
refactor to store HTLC failure status in pending_htlcs in Channel.
Implement error, warn, info, debug and trace macros, internally calling
an instance of Logger, and passing it to every main structures
Build-time or client-side filtering.
Issue #54
This patch got a bit bigger than I'd intended, but primarily this
unifies force_shutdown() handling so all the callsites at least
look similar. It also fails backwards any HTLCs which were
completely pending (ie hadn't been committed to) and ensures we
broadcast our local commitment transaction. It also adds a
force_close_channel method to ChannelManager to expose
force-closure.
