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DRAFT Demo payjoin e2e
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This is still broken because as far as I can tell the signer
will not sign with a missing RedeemScript / WitnessScript. And those
are missing.
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@DanGould
DanGould committed Dec 16, 2024
1 parent d5e73df commit a276d2d
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33 changes: 33 additions & 0 deletions .idea/workspace.xml
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234 changes: 133 additions & 101 deletions lib/_pkg/payjoin/manager.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -158,9 +158,11 @@ Future<String?> pollSender(Sender sender) async {
V2PostContext postReqCtx;
try {
final result = await sender.extractV2(ohttpProxyUrl: ohttpProxyUrl);
print('extracted v2');
postReq = result.$1;
postReqCtx = result.$2;
} catch (e) {
print('failed to extract v2. err: $e');
try {
final (req, v1Ctx) = await sender.extractV1();
print('Posting Original PSBT Payload request...');
Expand All @@ -187,28 +189,39 @@ Future<String?> pollSender(Sender sender) async {
},
body: postReq.body,
);
final getCtx = await postReqCtx.processResponse(
response: postRes.bodyBytes,
);
String? proposalPsbt;
while (true) {
final (getRequest, getReqCtx) = await getCtx.extractReq(
ohttpRelay: ohttpProxyUrl,
);
final getRes = await http.post(
Uri.parse(getRequest.url.asString()),
headers: {
'Content-Type': getRequest.contentType,
},
body: getRequest.body,
);
proposalPsbt = await getCtx.processResponse(
response: getRes.bodyBytes,
ohttpCtx: getReqCtx,
try {
print('got post response');
final getCtx = await postReqCtx.processResponse(
response: postRes.bodyBytes,
);
break;
print('processed post response');
String? proposalPsbt;
while (true) {
print('extracting get request');
final (getRequest, getReqCtx) = await getCtx.extractReq(
ohttpRelay: ohttpProxyUrl,
);
print('got get request');
final getRes = await http.post(
Uri.parse(getRequest.url.asString()),
headers: {
'Content-Type': getRequest.contentType,
},
body: getRequest.body,
);
print('got get response');
proposalPsbt = await getCtx.processResponse(
response: getRes.bodyBytes,
ohttpCtx: getReqCtx,
);
print('processed get response');
break;
}
return proposalPsbt;
} catch (e) {
print('err: $e');
throw Exception('Error occurred while polling sender');
}
return proposalPsbt;
}

Future<bool> addressExistsInWallet(String address, bdk.Wallet bdkWallet) async {
Expand Down Expand Up @@ -343,24 +356,26 @@ Future<void> _isolateSender(List<dynamic> args) async {

// SIGN AND BROADCAST ---------------------------
try {
print('signing');
final psbtStruct =
await bdk.PartiallySignedTransaction.fromString(proposal!);
await wallet.sign(
psbt: psbtStruct,
signOptions: const bdk.SignOptions(
trustWitnessUtxo: false,
trustWitnessUtxo: true,
allowAllSighashes: false,
removePartialSigs: true,
tryFinalize: true,
signWithTapInternalKey: false,
allowGrinding: true,
),
);

print('signed');
final finalizedTx = psbtStruct.extractTx();
final signedPsbt = psbtStruct.toString();

//Broadcast the transaction
print('broadcasting');
final broadcastedTx =
await blockchain.broadcast(transaction: finalizedTx);
print('Broadcasted transaction: $broadcastedTx');
Expand Down Expand Up @@ -430,17 +445,22 @@ void _isolateReceiver(List<dynamic> args) async {
while (unchecked_proposal == null) {
try {
final (req, context) = await receiver.extractReq();
print('making request');
final ohttpResponse = await http.post(
Uri.parse(req.url.asString()),
headers: {
'Content-Type': req.contentType,
},
body: req.body,
);
print('got unchecked response');
unchecked_proposal = await receiver.processRes(
body: ohttpResponse.bodyBytes,
ctx: context,
);
if (unchecked_proposal != null) {
break;
}
} catch (e) {
sendPort.send(
Err(
Expand All @@ -452,24 +472,24 @@ void _isolateReceiver(List<dynamic> args) async {
break;
}
}
if (unchecked_proposal == null) {
print('FAILED TO GET PROPOSAL');
}
final payjoin_proposal = await processPayjoinProposal(
unchecked_proposal!,
isTestnet,
wallet,
blockchain,
);
print('payjoin proposal: $payjoin_proposal');
try {
final (postReq, ohttpCtx) = await payjoin_proposal.extractV2Req();
print('extracted v2 req');
final postRes = await http.post(
Uri.parse(postReq.url.asString()),
headers: {
'Content-Type': postReq.contentType,
},
body: postReq.body,
);
print('processed res');
await payjoin_proposal.processRes(
res: postRes.bodyBytes,
ohttpContext: ohttpCtx,
Expand Down Expand Up @@ -498,92 +518,104 @@ Future<PayjoinProposal> processPayjoinProposal(
final fallbackTx = await proposal.extractTxToScheduleBroadcast();
print('fallback tx (broadcast this if payjoin fails): $fallbackTx');

// Receive Check 1: can broadcast
final pj1 = await proposal.assumeInteractiveReceiver();
// Receive Check 2: original PSBT has no receiver-owned inputs
final pj2 = await pj1.checkInputsNotOwned(
isOwned: (inputScript) async {
final address = await bdk.Address.fromScript(
script: bdk.ScriptBuf(bytes: inputScript),
network: isTestnet ? bdk.Network.testnet : bdk.Network.bitcoin,
);
return await addressExistsInWallet(address.toString(), wallet);
},
);
// Receive Check 3: sender inputs have not been seen before (prevent probing attacks)
final pj3 = await pj2.checkNoInputsSeenBefore(
isKnown: (input) {
// TODO: keep track of seen inputs in hive storage?
return false;
},
);
try {
// Receive Check 1: can broadcast
print('check1');
final pj1 = await proposal.assumeInteractiveReceiver();
print('check2');
// Receive Check 2: original PSBT has no receiver-owned inputs
final pj2 = await pj1.checkInputsNotOwned(
isOwned: (inputScript) async {
final address = await bdk.Address.fromScript(
script: bdk.ScriptBuf(bytes: inputScript),
network: isTestnet ? bdk.Network.testnet : bdk.Network.bitcoin,
);
return await addressExistsInWallet(address.toString(), wallet);
},
);
// Receive Check 3: sender inputs have not been seen before (prevent probing attacks)
print('check3');
final pj3 = await pj2.checkNoInputsSeenBefore(
isKnown: (input) {
// TODO: keep track of seen inputs in hive storage?
return false;
},
);

// Identify receiver outputs
final pj4 = await pj3.identifyReceiverOutputs(
isReceiverOutput: (outputScript) async {
final address = await bdk.Address.fromScript(
script: bdk.ScriptBuf(bytes: outputScript),
network: isTestnet ? bdk.Network.testnet : bdk.Network.bitcoin,
);
return await addressExistsInWallet(address.toString(), wallet);
},
);
final pj5 = await pj4.commitOutputs();
// Identify receiver outputs
print('check4');
final pj4 = await pj3.identifyReceiverOutputs(
isReceiverOutput: (outputScript) async {
final address = await bdk.Address.fromScript(
script: bdk.ScriptBuf(bytes: outputScript),
network: isTestnet ? bdk.Network.testnet : bdk.Network.bitcoin,
);
return await addressExistsInWallet(address.toString(), wallet);
},
);
final pj5 = await pj4.commitOutputs();

// Contribute receiver inputs
final utxos = await getSpendableUtxosFromBdkWallet(
wallet,
isTestnet ? bdk.Network.testnet : bdk.Network.bitcoin,
);
final inputs = await Future.wait(
utxos.map((utxo) => inputPairFromUtxo(utxo, isTestnet)),
);
final selected_utxo = await pj5.tryPreservingPrivacy(
candidateInputs: inputs,
);
final pj6 = await pj5.contributeInputs(replacementInputs: [selected_utxo]);
final pj7 = await pj6.commitInputs();

// Finalize proposal
final payjoin_proposal = await pj7.finalizeProposal(
processPsbt: (String psbt) async {
// TODO: sign PSBT
final psbtStruct = await bdk.PartiallySignedTransaction.fromString(psbt);
await wallet.sign(
psbt: psbtStruct,
signOptions: const bdk.SignOptions(
trustWitnessUtxo: false,
allowAllSighashes: false,
removePartialSigs: true,
tryFinalize: true,
signWithTapInternalKey: false,
allowGrinding: true,
),
);
return psbt;
},
maxFeeRateSatPerVb: BigInt.zero,
);
return payjoin_proposal;
// Contribute receiver inputs
print('get spendable utxos');
final unspent = wallet.listUnspent();
final inputs = await Future.wait(
unspent.map((unspent) => inputPairFromUtxo(unspent, isTestnet)),
);
print('selected utxo');
final selected_utxo = await pj5.tryPreservingPrivacy(
candidateInputs: inputs,
);
print('contribute inputs');
final pj6 = await pj5.contributeInputs(replacementInputs: [selected_utxo]);
print('commit inputs');
final pj7 = await pj6.commitInputs();

// Finalize proposal
print('finalize proposal');
final payjoin_proposal = await pj7.finalizeProposal(
processPsbt: (String psbt) async {
print('finalizeProposal psbt $psbt');
// TODO: sign PSBT
final psbtStruct =
await bdk.PartiallySignedTransaction.fromString(psbt);
print('unsigned psbtStruct $psbtStruct');
final signed = await wallet.sign(
psbt: psbtStruct,
signOptions: const bdk.SignOptions(
trustWitnessUtxo: false,
allowAllSighashes: false,
removePartialSigs: true,
tryFinalize: true,
signWithTapInternalKey: true,
allowGrinding: true,
),
);
print('signed $signed');
final signedPsbt = psbtStruct.toString();
print('signedPsbt $signedPsbt');
return signedPsbt;
},
maxFeeRateSatPerVb: BigInt.from(10000),
);
return payjoin_proposal;
} catch (e) {
print('err: $e');
throw Exception('Error occurred while finalizing proposal');
}
}

Future<InputPair> inputPairFromUtxo(UTXO utxo, bool isTestnet) async {
// TODO: this seems like a roundabout way of getting the script pubkey
final address = await bdk.Address.fromString(
s: utxo.address.address,
network: isTestnet ? bdk.Network.testnet : bdk.Network.bitcoin,
);
final spk = address.scriptPubkey().bytes;
Future<InputPair> inputPairFromUtxo(bdk.LocalUtxo utxo, bool isTestnet) async {
final psbtin = PsbtInput(
// We should be able to merge these bdk & payjoin rust-bitcoin types with bitcoin-ffi eventually
witnessUtxo: TxOut(
value: BigInt.from(utxo.value),
scriptPubkey: spk,
value: utxo.txout.value,
scriptPubkey: utxo.txout.scriptPubkey.bytes,
),
// TODO: redeem script/witness script?
);
// TODO: perhaps TxIn.default() should be exposed in payjoin_flutter api
final txin = TxIn(
previousOutput: OutPoint(txid: utxo.txid, vout: utxo.txIndex),
previousOutput:
OutPoint(txid: utxo.outpoint.txid, vout: utxo.outpoint.vout),
scriptSig: await Script.newInstance(rawOutputScript: []),
sequence: 0xFFFFFFFF,
witness: [],
Expand Down
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