//! Run an XMR/BTC swap in the role of Alice.
//! Alice holds XMR and wishes receive BTC.
use crate ::bitcoin ::ExpiredTimelocks ;
use crate ::env ::Config ;
use crate ::protocol ::alice ::event_loop ::EventLoopHandle ;
use crate ::protocol ::alice ::{ AliceState , Swap } ;
use crate ::{ bitcoin , database , monero } ;
use anyhow ::{ bail , Context , Result } ;
use tokio ::select ;
use tokio ::time ::timeout ;
use tracing ::{ error , info } ;
use uuid ::Uuid ;
pub async fn run ( swap : Swap ) -> Result < AliceState > {
run_until ( swap , | _ | false ) . await
}
#[ tracing::instrument(name = " swap " , skip(swap,exit_early), fields(id = %swap.swap_id), err) ]
pub async fn run_until ( mut swap : Swap , exit_early : fn ( & AliceState ) -> bool ) -> Result < AliceState > {
let mut current_state = swap . state ;
while ! is_complete ( & current_state ) & & ! exit_early ( & current_state ) {
current_state = next_state (
swap . swap_id ,
current_state ,
& mut swap . event_loop_handle ,
swap . bitcoin_wallet . as_ref ( ) ,
swap . monero_wallet . as_ref ( ) ,
& swap . env_config ,
)
. await ? ;
let db_state = ( & current_state ) . into ( ) ;
swap . db
. insert_latest_state ( swap . swap_id , database ::Swap ::Alice ( db_state ) )
. await ? ;
}
Ok ( current_state )
}
async fn next_state (
swap_id : Uuid ,
state : AliceState ,
event_loop_handle : & mut EventLoopHandle ,
bitcoin_wallet : & bitcoin ::Wallet ,
monero_wallet : & monero ::Wallet ,
env_config : & Config ,
) -> Result < AliceState > {
info ! ( "Current state: {}" , state ) ;
Ok ( match state {
AliceState ::Started { state3 } = > {
let tx_lock_status = bitcoin_wallet . subscribe_to ( state3 . tx_lock . clone ( ) ) . await ;
match timeout (
env_config . bitcoin_lock_confirmed_timeout ,
tx_lock_status . wait_until_final ( ) ,
)
. await
{
Err ( _ ) = > {
tracing ::info ! (
"TxLock lock did not get {} confirmations in {} minutes" ,
env_config . bitcoin_finality_confirmations ,
env_config . bitcoin_lock_confirmed_timeout . as_secs_f64 ( ) / 60.0
) ;
AliceState ::SafelyAborted
}
Ok ( res ) = > {
res ? ;
AliceState ::BtcLocked { state3 }
}
}
}
AliceState ::BtcLocked { state3 } = > {
match state3 . expired_timelocks ( bitcoin_wallet ) . await ? {
ExpiredTimelocks ::None = > {
// Record the current monero wallet block height so we don't have to scan from
// block 0 for scenarios where we create a refund wallet.
let monero_wallet_restore_blockheight = monero_wallet . block_height ( ) . await ? ;
let transfer_proof = monero_wallet
. transfer ( state3 . lock_xmr_transfer_request ( ) )
. await ? ;
AliceState ::XmrLockTransactionSent {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
}
_ = > AliceState ::SafelyAborted ,
}
}
AliceState ::XmrLockTransactionSent {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
} = > match state3 . expired_timelocks ( bitcoin_wallet ) . await ? {
ExpiredTimelocks ::None = > {
monero_wallet
. watch_for_transfer ( state3 . lock_xmr_watch_request ( transfer_proof . clone ( ) , 1 ) )
. await
. with_context ( | | {
format! (
"Failed to watch for transfer of XMR in transaction {}" ,
transfer_proof . tx_hash ( )
)
} ) ? ;
AliceState ::XmrLocked {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
}
_ = > AliceState ::CancelTimelockExpired {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
} ,
} ,
AliceState ::XmrLocked {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
} = > {
let tx_lock_status = bitcoin_wallet . subscribe_to ( state3 . tx_lock . clone ( ) ) . await ;
tokio ::select ! {
result = event_loop_handle . send_transfer_proof ( transfer_proof . clone ( ) ) = > {
result ? ;
AliceState ::XmrLockTransferProofSent {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
} ,
_ = tx_lock_status . wait_until_confirmed_with ( state3 . cancel_timelock ) = > {
AliceState ::CancelTimelockExpired {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
}
}
}
AliceState ::XmrLockTransferProofSent {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
} = > {
let tx_lock_status = bitcoin_wallet . subscribe_to ( state3 . tx_lock . clone ( ) ) . await ;
select ! {
biased ; // make sure the cancel timelock expiry future is polled first
_ = tx_lock_status . wait_until_confirmed_with ( state3 . cancel_timelock ) = > {
AliceState ::CancelTimelockExpired {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
}
enc_sig = event_loop_handle . recv_encrypted_signature ( ) = > {
tracing ::info ! ( "Received encrypted signature" ) ;
AliceState ::EncSigLearned {
monero_wallet_restore_blockheight ,
transfer_proof ,
encrypted_signature : Box ::new ( enc_sig ? ) ,
state3 ,
}
}
}
}
AliceState ::EncSigLearned {
monero_wallet_restore_blockheight ,
transfer_proof ,
encrypted_signature ,
state3 ,
} = > match state3 . expired_timelocks ( bitcoin_wallet ) . await ? {
ExpiredTimelocks ::None = > {
let tx_lock_status = bitcoin_wallet . subscribe_to ( state3 . tx_lock . clone ( ) ) . await ;
match state3 . signed_redeem_transaction ( * encrypted_signature ) {
Ok ( tx ) = > match bitcoin_wallet . broadcast ( tx , "redeem" ) . await {
Ok ( ( _ , subscription ) ) = > match subscription . wait_until_final ( ) . await {
Ok ( _ ) = > AliceState ::BtcRedeemed ,
Err ( e ) = > {
bail ! ( "Waiting for Bitcoin transaction finality failed with {}! The redeem transaction was published, but it is not ensured that the transaction was included! You're screwed." , e )
}
} ,
Err ( e ) = > {
error ! ( "Publishing the redeem transaction failed with {}, attempting to wait for cancellation now. If you restart the application before the timelock is expired publishing the redeem transaction will be retried." , e ) ;
tx_lock_status
. wait_until_confirmed_with ( state3 . cancel_timelock )
. await ? ;
AliceState ::CancelTimelockExpired {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
}
} ,
Err ( e ) = > {
error ! ( "Constructing the redeem transaction failed with {}, attempting to wait for cancellation now." , e ) ;
tx_lock_status
. wait_until_confirmed_with ( state3 . cancel_timelock )
. await ? ;
AliceState ::CancelTimelockExpired {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
}
}
}
_ = > AliceState ::CancelTimelockExpired {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
} ,
} ,
AliceState ::CancelTimelockExpired {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
} = > {
if state3 . check_for_tx_cancel ( bitcoin_wallet ) . await . is_err ( ) {
// If Bob hasn't yet broadcasted the cancel transaction, Alice has to publish it
// to be able to eventually punish. Since the punish timelock is
// relative to the publication of the cancel transaction we have to ensure it
// gets published once the cancel timelock expires.
if let Err ( e ) = state3 . submit_tx_cancel ( bitcoin_wallet ) . await {
tracing ::debug ! (
"Assuming cancel transaction is already broadcasted because: {:#}" ,
e
)
}
}
AliceState ::BtcCancelled {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
}
AliceState ::BtcCancelled {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
} = > {
let tx_refund_status = bitcoin_wallet . subscribe_to ( state3 . tx_refund ( ) ) . await ;
let tx_cancel_status = bitcoin_wallet . subscribe_to ( state3 . tx_cancel ( ) ) . await ;
select ! {
seen_refund = tx_refund_status . wait_until_seen ( ) = > {
seen_refund . context ( "Failed to monitor refund transaction" ) ? ;
let published_refund_tx = bitcoin_wallet . get_raw_transaction ( state3 . tx_refund ( ) . txid ( ) ) . await ? ;
let spend_key = state3 . extract_monero_private_key ( published_refund_tx ) ? ;
AliceState ::BtcRefunded {
monero_wallet_restore_blockheight ,
transfer_proof ,
spend_key ,
state3 ,
}
}
_ = tx_cancel_status . wait_until_confirmed_with ( state3 . punish_timelock ) = > {
AliceState ::BtcPunishable {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
}
}
}
}
AliceState ::BtcRefunded {
monero_wallet_restore_blockheight ,
transfer_proof ,
spend_key ,
state3 ,
} = > {
state3
. refund_xmr (
monero_wallet ,
monero_wallet_restore_blockheight ,
swap_id . to_string ( ) ,
spend_key ,
transfer_proof ,
)
. await ? ;
AliceState ::XmrRefunded
}
AliceState ::BtcPunishable {
monero_wallet_restore_blockheight ,
transfer_proof ,
state3 ,
} = > {
let punish = state3 . punish_btc ( bitcoin_wallet ) . await ;
match punish {
Ok ( _ ) = > AliceState ::BtcPunished ,
Err ( e ) = > {
tracing ::warn ! (
"Falling back to refund because punish transaction failed with {:#}" ,
e
) ;
// Upon punish failure we assume that the refund tx was included but we
// missed seeing it. In case we fail to fetch the refund tx we fail
// with no state update because it is unclear what state we should transition
// to. It does not help to race punish and refund inclusion,
// because a punish tx failure is not recoverable (besides re-trying) if the
// refund tx was not included.
let published_refund_tx = bitcoin_wallet
. get_raw_transaction ( state3 . tx_refund ( ) . txid ( ) )
. await ? ;
let spend_key = state3 . extract_monero_private_key ( published_refund_tx ) ? ;
AliceState ::BtcRefunded {
monero_wallet_restore_blockheight ,
transfer_proof ,
spend_key ,
state3 ,
}
}
}
}
AliceState ::XmrRefunded = > AliceState ::XmrRefunded ,
AliceState ::BtcRedeemed = > AliceState ::BtcRedeemed ,
AliceState ::BtcPunished = > AliceState ::BtcPunished ,
AliceState ::SafelyAborted = > AliceState ::SafelyAborted ,
} )
}
fn is_complete ( state : & AliceState ) -> bool {
matches! (
state ,
AliceState ::XmrRefunded
| AliceState ::BtcRedeemed
| AliceState ::BtcPunished
| AliceState ::SafelyAborted
)
}