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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 | 1x 1x 1x 1x 1x 1x | import {
LockTime,
OutPoint,
Script,
Tx,
TxBuilder,
Value,
} from '@node-dlc/bitcoin';
import {
DlcAcceptWithoutSigs,
DlcOfferV0,
FundingInputV0,
MessageType,
} from '@node-dlc/messaging';
import Decimal from 'decimal.js';
import { DualFundingTxFinalizer } from './TxFinalizer';
export class DlcTxBuilder {
constructor(
readonly dlcOffer: DlcOfferV0,
readonly dlcAccept: DlcAcceptWithoutSigs,
) {}
public buildFundingTransaction(): Tx {
const txBuilder = new BatchDlcTxBuilder([this.dlcOffer], [this.dlcAccept]);
return txBuilder.buildFundingTransaction();
}
}
export class BatchDlcTxBuilder {
constructor(
readonly dlcOffers: DlcOfferV0[],
readonly dlcAccepts: DlcAcceptWithoutSigs[],
) {}
public buildFundingTransaction(): Tx {
const tx = new TxBuilder();
tx.version = 2;
tx.locktime = LockTime.zero();
if (this.dlcOffers.length !== this.dlcAccepts.length)
throw Error('DlcOffers and DlcAccepts must be the same length');
if (this.dlcOffers.length === 0) throw Error('DlcOffers must not be empty');
if (this.dlcAccepts.length === 0)
throw Error('DlcAccepts must not be empty');
// Ensure all DLC offers and accepts have the same funding inputs
this.ensureSameFundingInputs();
const multisigScripts: Script[] = [];
for (let i = 0; i < this.dlcOffers.length; i++) {
const offer = this.dlcOffers[i];
const accept = this.dlcAccepts[i];
multisigScripts.push(
Buffer.compare(offer.fundingPubKey, accept.fundingPubKey) === -1
? Script.p2msLock(2, offer.fundingPubKey, accept.fundingPubKey)
: Script.p2msLock(2, accept.fundingPubKey, offer.fundingPubKey),
);
}
const witScripts = multisigScripts.map((multisigScript) =>
Script.p2wshLock(multisigScript),
);
const finalizer = new DualFundingTxFinalizer(
this.dlcOffers[0].fundingInputs,
this.dlcOffers[0].payoutSPK,
this.dlcOffers[0].changeSPK,
this.dlcAccepts[0].fundingInputs,
this.dlcAccepts[0].payoutSPK,
this.dlcAccepts[0].changeSPK,
this.dlcOffers[0].feeRatePerVb,
this.dlcOffers.length,
);
this.dlcOffers[0].fundingInputs.forEach((input) => {
if (input.type !== MessageType.FundingInputV0)
throw Error('FundingInput must be V0');
});
const offerFundingInputs: FundingInputV0[] = this.dlcOffers[0].fundingInputs.map(
(input) => input as FundingInputV0,
);
const offerTotalFunding = offerFundingInputs.reduce((total, input) => {
return total + input.prevTx.outputs[input.prevTxVout].value.sats;
}, BigInt(0));
const acceptTotalFunding = this.dlcAccepts[0].fundingInputs.reduce(
(total, input) => {
return total + input.prevTx.outputs[input.prevTxVout].value.sats;
},
BigInt(0),
);
const fundingInputs: FundingInputV0[] = [
...offerFundingInputs,
...this.dlcAccepts[0].fundingInputs,
];
fundingInputs.sort(
(a, b) => Number(a.inputSerialId) - Number(b.inputSerialId),
);
fundingInputs.forEach((input) => {
tx.addInput(
OutPoint.fromString(
`${input.prevTx.txId.toString()}:${input.prevTxVout}`,
),
);
});
const offerInput = this.dlcOffers.reduce(
(total, offer) => total + offer.offerCollateralSatoshis,
BigInt(0),
);
const acceptInput = this.dlcAccepts.reduce(
(total, accept) => total + accept.acceptCollateralSatoshis,
BigInt(0),
);
const totalInputs = this.dlcOffers.map((offer, i) => {
const offerInput = offer.offerCollateralSatoshis;
const acceptInput = this.dlcAccepts[i].acceptCollateralSatoshis;
return offerInput + acceptInput;
});
const fundingValues = totalInputs.map((totalInput) => {
const offerFutureFeePerOffer = new Decimal(
finalizer.offerFutureFee.toString(),
)
.div(this.dlcOffers.length)
.ceil()
.toNumber();
const acceptFutureFeePerAccept = new Decimal(
finalizer.acceptFutureFee.toString(),
)
.div(this.dlcAccepts.length)
.ceil()
.toNumber();
return (
totalInput +
Value.fromSats(offerFutureFeePerOffer).sats +
Value.fromSats(acceptFutureFeePerAccept).sats
);
});
const offerChangeValue =
offerTotalFunding - offerInput - finalizer.offerFees;
const acceptChangeValue =
acceptTotalFunding - acceptInput - finalizer.acceptFees;
const outputs: Output[] = [];
witScripts.forEach((witScript, i) => {
outputs.push({
value: Value.fromSats(Number(fundingValues[i])),
script: witScript,
serialId: this.dlcOffers[i].fundOutputSerialId,
});
});
outputs.push({
value: Value.fromSats(Number(offerChangeValue)),
script: Script.p2wpkhLock(this.dlcOffers[0].changeSPK.slice(2)),
serialId: this.dlcOffers[0].changeSerialId,
});
outputs.push({
value: Value.fromSats(Number(acceptChangeValue)),
script: Script.p2wpkhLock(this.dlcAccepts[0].changeSPK.slice(2)),
serialId: this.dlcAccepts[0].changeSerialId,
});
outputs.sort((a, b) => Number(a.serialId) - Number(b.serialId));
outputs.forEach((output) => {
tx.addOutput(output.value, output.script);
});
return tx.toTx();
}
private ensureSameFundingInputs(): void {
// Check for offers
const referenceOfferInputs = this.dlcOffers[0].fundingInputs.map((input) =>
input.serialize().toString('hex'),
);
for (let i = 1; i < this.dlcOffers.length; i++) {
const currentInputs = this.dlcOffers[i].fundingInputs.map((input) =>
input.serialize().toString('hex'),
);
if (!this.arraysEqual(referenceOfferInputs, currentInputs)) {
throw new Error(
`Funding inputs for offer ${i} do not match the first offer's funding inputs.`,
);
}
}
// Check for accepts
const referenceAcceptInputs = this.dlcAccepts[0].fundingInputs.map(
(input) => input.serialize().toString('hex'),
);
for (let i = 1; i < this.dlcAccepts.length; i++) {
const currentInputs = this.dlcAccepts[i].fundingInputs.map((input) =>
input.serialize().toString('hex'),
);
if (!this.arraysEqual(referenceAcceptInputs, currentInputs)) {
throw new Error(
`Funding inputs for accept ${i} do not match the first accept's funding inputs.`,
);
}
}
}
private arraysEqual(arr1: string[], arr2: string[]): boolean {
if (arr1.length !== arr2.length) return false;
for (let i = 0; i < arr1.length; i++) {
if (arr1[i] !== arr2[i]) return false;
}
return true;
}
}
interface Output {
value: Value;
script: Script;
serialId: bigint;
}
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