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Add batching tests
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Adds two integration tests for transaction cut-through:
- Receiver UTXO consolidation
- Receiver forwarding payment to a third-party

Also fixes some issues in outputs and inputs contribution logic that
became apparent while testing.
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spacebear21 committed Aug 26, 2024
1 parent c595f59 commit a745af6
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Showing 2 changed files with 239 additions and 31 deletions.
4 changes: 2 additions & 2 deletions payjoin/src/receive/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -587,7 +587,7 @@ impl WantsInputs {
let change_amount = receiver_input_amount - receiver_min_input_amount;
payjoin_psbt.unsigned_tx.output[self.change_vout].value += change_amount;
} else {
todo!("Return an error?");
todo!("Input amount is not enough to cover additional output value");
}

WantsInputs {
Expand All @@ -612,7 +612,7 @@ impl WantsInputs {
.output
.iter()
.fold(Amount::ZERO, |acc, output| acc + output.value);
max(Amount::ZERO, output_amount - original_output_amount)
output_amount.checked_sub(original_output_amount).unwrap_or(Amount::ZERO)
}

/// Proceed to the proposal finalization step.
Expand Down
266 changes: 237 additions & 29 deletions payjoin/tests/integration.rs
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ mod integration {

use bitcoin::policy::DEFAULT_MIN_RELAY_TX_FEE;
use bitcoin::psbt::Psbt;
use bitcoin::{Amount, FeeRate, OutPoint, Weight};
use bitcoin::{Amount, FeeRate, OutPoint, TxOut, Weight};
use bitcoind::bitcoincore_rpc::json::{AddressType, WalletProcessPsbtResult};
use bitcoind::bitcoincore_rpc::{self, RpcApi};
use log::{log_enabled, Level};
Expand Down Expand Up @@ -58,7 +58,7 @@ mod integration {
// **********************
// Inside the Receiver:
// this data would transit from one party to another over the network in production
let response = handle_v1_pj_request(req, headers, &receiver);
let response = handle_v1_pj_request(req, headers, &receiver, None, None, None);
// this response would be returned as http response to the sender

// **********************
Expand Down Expand Up @@ -364,7 +364,7 @@ mod integration {
// **********************
// Inside the Receiver:
// this data would transit from one party to another over the network in production
let response = handle_v1_pj_request(req, headers, &receiver);
let response = handle_v1_pj_request(req, headers, &receiver, None, None, None);
// this response would be returned as http response to the sender

// **********************
Expand Down Expand Up @@ -736,6 +736,197 @@ mod integration {
}
}

#[cfg(not(feature = "v2"))]
mod batching {
use payjoin::UriExt;

use super::*;

// In this test the receiver consolidates a bunch of UTXOs into the destination output
#[test]
fn receiver_consolidates_utxos() -> Result<(), BoxError> {
init_tracing();
let (bitcoind, sender, receiver) = init_bitcoind_sender_receiver()?;
// Generate more UTXOs for the receiver
let receiver_address =
receiver.get_new_address(None, Some(AddressType::Bech32))?.assume_checked();
bitcoind.client.generate_to_address(199, &receiver_address)?;
let receiver_utxos = receiver.list_unspent(None, None, None, None, None).unwrap();
assert_eq!(100, receiver_utxos.len(), "receiver doesn't have enough UTXOs");
assert_eq!(
Amount::from_btc(3700.0)?, // 48*50.0 + 52*25.0 (halving occurs every 150 blocks)
receiver.get_balances()?.mine.trusted,
"receiver doesn't have enough bitcoin"
);

// Receiver creates the payjoin URI
let pj_receiver_address = receiver.get_new_address(None, None)?.assume_checked();
let pj_uri = PjUriBuilder::new(pj_receiver_address, EXAMPLE_URL.to_owned())
.amount(Amount::ONE_BTC)
.build();

// **********************
// Inside the Sender:
// Sender create a funded PSBT (not broadcasted) to address with amount given in the pj_uri
let uri = Uri::from_str(&pj_uri.to_string())
.unwrap()
.assume_checked()
.check_pj_supported()
.unwrap();
let psbt = build_original_psbt(&sender, &uri)?;
log::debug!("Original psbt: {:#?}", psbt);
let max_additional_fee = Amount::from_sat(1000);
let (req, ctx) = RequestBuilder::from_psbt_and_uri(psbt.clone(), uri)?
.build_with_additional_fee(max_additional_fee, None, FeeRate::ZERO, false)?
.extract_v1()?;
let headers = HeaderMock::new(&req.body, req.content_type);

// **********************
// Inside the Receiver:
// this data would transit from one party to another over the network in production
let outputs = vec![TxOut {
value: Amount::from_btc(3700.0)?,
script_pubkey: receiver
.get_new_address(None, None)?
.assume_checked()
.script_pubkey(),
}];
let drain_script = outputs[0].script_pubkey.clone();
let inputs = receiver_utxos
.iter()
.map(|utxo| {
let outpoint = OutPoint { txid: utxo.txid, vout: utxo.vout };
let txo = bitcoin::TxOut {
value: utxo.amount,
script_pubkey: utxo.script_pub_key.clone(),
};
(outpoint, txo)
})
.collect();
let response = handle_v1_pj_request(
req,
headers,
&receiver,
Some(outputs),
Some(&drain_script),
Some(inputs),
);
// this response would be returned as http response to the sender

// **********************
// Inside the Sender:
// Sender checks, signs, finalizes, extracts, and broadcasts
let checked_payjoin_proposal_psbt = ctx.process_response(&mut response.as_bytes())?;
let payjoin_tx = extract_pj_tx(&sender, checked_payjoin_proposal_psbt)?;
sender.send_raw_transaction(&payjoin_tx)?;

// Check resulting transaction and balances
let network_fees = predicted_tx_weight(&payjoin_tx) * FeeRate::BROADCAST_MIN;
// The sender pays (original tx fee + max additional fee)
let original_tx_fee = psbt.fee()?;
let sender_fee = original_tx_fee + max_additional_fee;
// The receiver pays the difference
let receiver_fee = network_fees - sender_fee;
assert_eq!(payjoin_tx.input.len(), 101);
assert_eq!(payjoin_tx.output.len(), 2);
assert_eq!(
receiver.get_balances()?.mine.untrusted_pending,
Amount::from_btc(3701.0)? - receiver_fee
);
assert_eq!(
sender.get_balances()?.mine.untrusted_pending,
Amount::from_btc(49.0)? - sender_fee
);
Ok(())
}

// In this test the receiver forwards part of the sender payment to another payee
#[test]
fn receiver_forwards_payment() -> Result<(), BoxError> {
init_tracing();
let (bitcoind, sender, receiver) = init_bitcoind_sender_receiver()?;
let third_party = bitcoind.create_wallet("third-party")?;

// Receiver creates the payjoin URI
let pj_receiver_address = receiver.get_new_address(None, None)?.assume_checked();
let pj_uri = PjUriBuilder::new(pj_receiver_address, EXAMPLE_URL.to_owned())
.amount(Amount::ONE_BTC)
.build();

// **********************
// Inside the Sender:
// Sender create a funded PSBT (not broadcasted) to address with amount given in the pj_uri
let uri = Uri::from_str(&pj_uri.to_string())
.unwrap()
.assume_checked()
.check_pj_supported()
.unwrap();
let psbt = build_original_psbt(&sender, &uri)?;
log::debug!("Original psbt: {:#?}", psbt);
let (req, ctx) = RequestBuilder::from_psbt_and_uri(psbt.clone(), uri)?
.build_with_additional_fee(Amount::from_sat(10000), None, FeeRate::ZERO, false)?
.extract_v1()?;
let headers = HeaderMock::new(&req.body, req.content_type);

// **********************
// Inside the Receiver:
// this data would transit from one party to another over the network in production
let outputs = vec![
TxOut {
value: Amount::from_sat(10000000),
script_pubkey: third_party
.get_new_address(None, None)?
.assume_checked()
.script_pubkey(),
},
TxOut {
value: Amount::from_sat(90000000),
script_pubkey: receiver
.get_new_address(None, None)?
.assume_checked()
.script_pubkey(),
},
];
let drain_script = outputs[1].script_pubkey.clone();
let inputs = vec![];
let response = handle_v1_pj_request(
req,
headers,
&receiver,
Some(outputs),
Some(&drain_script),
Some(inputs),
);
// this response would be returned as http response to the sender

// **********************
// Inside the Sender:
// Sender checks, signs, finalizes, extracts, and broadcasts
let checked_payjoin_proposal_psbt = ctx.process_response(&mut response.as_bytes())?;
let payjoin_tx = extract_pj_tx(&sender, checked_payjoin_proposal_psbt)?;
sender.send_raw_transaction(&payjoin_tx)?;

// Check resulting transaction and balances
let network_fees = predicted_tx_weight(&payjoin_tx) * FeeRate::BROADCAST_MIN;
// The sender pays original tx fee
let original_tx_fee = psbt.fee()?;
let sender_fee = original_tx_fee;
// The receiver pays the difference
let receiver_fee = network_fees - sender_fee;
assert_eq!(payjoin_tx.input.len(), 1);
assert_eq!(payjoin_tx.output.len(), 3);
assert_eq!(
receiver.get_balances()?.mine.untrusted_pending,
Amount::from_btc(0.9)? - receiver_fee
);
assert_eq!(third_party.get_balances()?.mine.untrusted_pending, Amount::from_btc(0.1)?);
// sender balance is considered "trusted" because all inputs in the transaction were
// created by their wallet
assert_eq!(sender.get_balances()?.mine.trusted, Amount::from_btc(49.0)? - sender_fee);
Ok(())
}
}

fn init_tracing() {
INIT_TRACING.get_or_init(|| {
let subscriber = FmtSubscriber::builder()
Expand Down Expand Up @@ -811,6 +1002,9 @@ mod integration {
req: Request,
headers: impl payjoin::receive::Headers,
receiver: &bitcoincore_rpc::Client,
custom_outputs: Option<Vec<TxOut>>,
drain_script: Option<&bitcoin::Script>,
custom_inputs: Option<Vec<(OutPoint, TxOut)>>,
) -> String {
// Receiver receive payjoin proposal, IRL it will be an HTTP request (over ssl or onion)
let proposal = payjoin::receive::UncheckedProposal::from_request(
Expand All @@ -819,7 +1013,8 @@ mod integration {
headers,
)
.unwrap();
let proposal = handle_proposal(proposal, receiver);
let proposal =
handle_proposal(proposal, receiver, custom_outputs, drain_script, custom_inputs);
assert!(!proposal.is_output_substitution_disabled());
let psbt = proposal.psbt();
tracing::debug!("Receiver's Payjoin proposal PSBT: {:#?}", &psbt);
Expand All @@ -829,6 +1024,9 @@ mod integration {
fn handle_proposal(
proposal: payjoin::receive::UncheckedProposal,
receiver: &bitcoincore_rpc::Client,
custom_outputs: Option<Vec<TxOut>>,
drain_script: Option<&bitcoin::Script>,
custom_inputs: Option<Vec<(OutPoint, TxOut)>>,
) -> payjoin::receive::PayjoinProposal {
// in a payment processor where the sender could go offline, this is where you schedule to broadcast the original_tx
let _to_broadcast_in_failure_case = proposal.extract_tx_to_schedule_broadcast();
Expand Down Expand Up @@ -869,33 +1067,43 @@ mod integration {
})
.expect("Receiver should have at least one output");

let payjoin = payjoin
.substitute_receiver_script(
&receiver.get_new_address(None, None).unwrap().assume_checked().script_pubkey(),
)
.expect("Could not substitute outputs")
.commit_outputs();

// Select receiver payjoin inputs. TODO Lock them.
let available_inputs = receiver.list_unspent(None, None, None, None, None).unwrap();
let candidate_inputs: HashMap<Amount, OutPoint> = available_inputs
.iter()
.map(|i| (i.amount, OutPoint { txid: i.txid, vout: i.vout }))
.collect();

let selected_outpoint = payjoin.try_preserving_privacy(candidate_inputs).expect("gg");
let selected_utxo = available_inputs
.iter()
.find(|i| i.txid == selected_outpoint.txid && i.vout == selected_outpoint.vout)
.unwrap();
let txo_to_contribute = bitcoin::TxOut {
value: selected_utxo.amount,
script_pubkey: selected_utxo.script_pub_key.clone(),
let payjoin = match custom_outputs {
Some(txos) => payjoin
.replace_receiver_outputs(txos, &drain_script.unwrap())
.expect("Could not substitute outputs"),
None => payjoin
.substitute_receiver_script(
&receiver.get_new_address(None, None).unwrap().assume_checked().script_pubkey(),
)
.expect("Could not substitute outputs"),
}
.commit_outputs();

let inputs = match custom_inputs {
Some(inputs) => inputs,
None => {
// Select receiver payjoin inputs. TODO Lock them.
let available_inputs = receiver.list_unspent(None, None, None, None, None).unwrap();
let candidate_inputs: HashMap<Amount, OutPoint> = available_inputs
.iter()
.map(|i| (i.amount, OutPoint { txid: i.txid, vout: i.vout }))
.collect();

let selected_outpoint =
payjoin.try_preserving_privacy(candidate_inputs).expect("gg");
let selected_utxo = available_inputs
.iter()
.find(|i| i.txid == selected_outpoint.txid && i.vout == selected_outpoint.vout)
.unwrap();
let txo_to_contribute = bitcoin::TxOut {
value: selected_utxo.amount,
script_pubkey: selected_utxo.script_pub_key.clone(),
};
vec![(selected_outpoint, txo_to_contribute)]
}
};

let payjoin = payjoin
.contribute_witness_inputs(vec![(selected_outpoint, txo_to_contribute)])
.commit_inputs();
let payjoin = payjoin.contribute_witness_inputs(inputs).commit_inputs();

let payjoin_proposal = payjoin
.finalize_proposal(
Expand Down

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