We don't need to hide the fields of this Behaviour as the only reason
for why this struct exists is because libp2p forces us to compose our
NetworkBehaviours into a new struct.
Awaiting the confirmations in an earlier state can cause trouble with resuming
swaps with short cancel expiries (test scenarios).
Since it is the responsibility of the refund state to ensure that the XMR can
be sweeped, we now ensure that the lock transaction has 10 confirmations before
refunding the XMR using generate_from_keys.
Sending the transfer transaction in a distinct state helps ensuring
that we do not send the Monero lock transaction twice in a restart
scenario.
Waiting for the first transaction confirmation in a separate state
helps ensuring that we send the transfer proof in a restart scenario.
Once we resume unfinished swaps upon startup we have to ensure that
it is safe for Alice to act.
If Bob has locked BTC it is only make sense for Alice to lock up the
XMR as long as no timelock has expired. Hence we abort if the BTC is
locked, but any timelock expired already.
In order for the re-construction of TxLock to be meaningful, we limit
`Message2` to the PSBT instead of the full struct. This is a breaking
change in the network layer.
The PSBT is valid if:
- It has at most two outputs (we allow a change output)
- One of the outputs pays the agreed upon amount to a shared output script
Resolves#260.
This allows us to remove all visibility modifiers from the message
fields because child modules (in this case {alice,bob}::state) can
always access private fields of structs.
It also moves the messages into a more natural place. Previously,
they were defined within the network layer even though they are
independent of the libp2p implementation.
To achieve this, we need to add some pure helpers to the state structs.
This has the added benefit that we can reduce the amount of code within
the swap function.
If TxLock does not confirm in a reasonable amount of time, Alice should
give up on the swap rather than waiting forever. Watching for TxLock in
the mempool is not required and it causes unnecessary complexity. What
if Alice does not see the transaction in mempool but it is already
confirmed? She will abort the swap for no reason.
Instead of watching for status changes directly on bitcoin::Wallet,
we return a Subscription object back to the caller. This subscription
object can be re-used multiple times.
Among other things, this now allows callers of `broadcast` to decide
on what to wait for given the returned Subscription object.
The new API is also more concise which allows us to remove some of
the functions on the actor states in favor of simple inline calls.
Co-authored-by: rishflab <rishflab@hotmail.com>
The request-response behaviour that is used for sending the transfer
proof actually has a functionality for buffering a message if we
are currently not connected. However, the request-response behaviour
also emits a dial attempt and **drops** all buffered messages if this
dial attempt fails. For us, the dial attempt will very likely always
fail because Bob is very likely behind NAT and we have to wait for
him to reconnect to us.
To mitigate this, we build our own buffer within the EventLoop and
send transfer proofs as soon as we are connected again.
Resolves#348.
The swap should not be concerned with connection handling. This is
the responsibility of the overall application.
All but the execution-setup NetworkBehaviour are `request-response`
behaviours. These have built-in functionality to automatically emit
a dial attempt in case we are not connected at the time we want to
send a message. We remove all of the manual dialling code from the
swap in favor of this behaviour.
Additionally, we make sure to establish a connection as soon as the
EventLoop gets started. In case we ever loose the connection to Alice,
we try to re-establish it.
Decomposing a RequestResponseEvent is quite verbose. We can introduce
a helper function that does the matching for us and delegates to
specific `From` implementations for the protocol specific bits.
319: Alice sweeps refunded funds into default wallet r=da-kami a=da-kami
Alice's refund scenario starts with generating the temporary wallet
from keys to claim the XMR which results in Alice' unloading the wallet.
Alice then loads her original wallet to be able to handle more swaps.
Since Alice is in the role of the long running daemon handling concurrent
swaps, the operation to close, claim and re-open her default wallet must
be atomic.
This PR adds an additional step, that sweeps all the refunded XMR back into
the default wallet. In order to ensure that this is possible, Alice has to
ensure that the locked XMR got enough confirmations.
These changes allow us to assert Alice's balance after refunding.
Co-authored-by: Daniel Karzel <daniel@comit.network>
If we enter a punish scenario we can be sure the punish timelock is expired.
Thus, we must be able to punish unless Bob published the refund transaction.
There is no benefit in racing punish against refund here, because we cannot recover from a punish tx failure anyway.
The logic was changed to:
Try to broadcast punish tx and await finality.
If either punish broadcasting of finality fails, try to fetch the refund transaction.
If it is available extract Bob's Monero key part and transition to refund.
If refund tx is not available fail without a status update.
Note that we do not distinguish different errors upon failure of punish, because
we cannot recover anyway. If we fail to retrieve Bob's refund tx, we just exit without
a status update so punish can be retried by resuming the swap.
Since Alice's refund scenario starts with generating the temporary wallet
from keys to claim the XMR which results in Alice' unloading the wallet.
Alice then loads her original wallet to be able to handle more swaps.
Since Alice is in the role of the long running daemon handling concurrent
swaps, the operation to close, claim and re-open her default wallet must
be atomic.
This PR adds an additional step, that sweeps all the refunded XMR back into
the default wallet. In order to ensure that this is possible, Alice has to
ensure that the locked XMR got enough confirmations.
These changes allow us to assert Alice's balance after refunding.
To achieve this, we decompose `watch_for_locked_xmr` into two parts:
1. A non-self-consuming function to construct a `WatchRequest`
2. A state transition that can now consume `self` again because
it is only called once within the whole select! expression.
Ideally, we would move more logic onto this state transition (like
comparing the actual amounts and fail the transition if it is not
valid). Doing so would have an unfortunate side-effect: We would
always wait for the full confirmations before checking whether or
not we actually receive enough XMR.
This allows us to have state transitions that consume self.
Instead of calling this function in all the branches, we can simply
make the whole match statement evaluate to the new state and perform
this functionality at the very end.
This allows us to move critical crypto logic onto `State3` which
holds all the necessary data which consequently allows us to get
rid of `lock_xmr` altogether by inlining it into the swap function.
The reduced indirection improves readability.
