Compute decoded tx CPFP data in the backend

backend/src/api/bitcoin/bitcoin.routes.ts

@@ -12,14 +12,14 @@ import backendInfo from '../backend-info';
 import transactionUtils from '../transaction-utils';
 import { IEsploraApi } from './esplora-api.interface';
 import loadingIndicators from '../loading-indicators';
-import { MempoolTransactionExtended, TransactionExtended } from '../../mempool.interfaces';
+import { TransactionExtended } from '../../mempool.interfaces';
 import logger from '../../logger';
 import blocks from '../blocks';
 import bitcoinClient from './bitcoin-client';
 import difficultyAdjustment from '../difficulty-adjustment';
 import transactionRepository from '../../repositories/TransactionRepository';
 import rbfCache from '../rbf-cache';
-import { calculateMempoolTxCpfp } from '../cpfp';
+import { calculateMempoolTxCpfp, calculateLocalTxCpfp } from '../cpfp';
 import { handleError } from '../../utils/api';
 
 class BitcoinRoutes {
@@ -50,6 +50,7 @@ class BitcoinRoutes {
       .get(config.MEMPOOL.API_URL_PREFIX + 'blocks-bulk/:from', this.getBlocksByBulk.bind(this))
       .get(config.MEMPOOL.API_URL_PREFIX + 'blocks-bulk/:from/:to', this.getBlocksByBulk.bind(this))
       .post(config.MEMPOOL.API_URL_PREFIX + 'prevouts', this.$getPrevouts)
+      .post(config.MEMPOOL.API_URL_PREFIX + 'cpfp', this.getCpfpLocalTx)
       // Temporarily add txs/package endpoint for all backends until esplora supports it
       .post(config.MEMPOOL.API_URL_PREFIX + 'txs/package', this.$submitPackage)
       ;
@@ -829,11 +830,11 @@ class BitcoinRoutes {
     try {
       const outpoints = req.body;
       if (!Array.isArray(outpoints) || outpoints.some((item) => !/^[a-fA-F0-9]{64}$/.test(item.txid) || typeof item.vout !== 'number')) {
-        return res.status(400).json({ error: 'Invalid input format' });
+        return res.status(400).json({ message: 'Invalid input format' });
       }
 
       if (outpoints.length > 100) {
-        return res.status(400).json({ error: 'Too many prevouts requested' });
+        return res.status(400).json({ message: 'Too many prevouts requested' });
       }
 
       const result = Array(outpoints.length).fill(null);
@@ -842,12 +843,14 @@ class BitcoinRoutes {
       for (let i = 0; i < outpoints.length; i++) {
         const outpoint = outpoints[i];
         let prevout: IEsploraApi.Vout | null = null;
-        let tx: MempoolTransactionExtended | null = null;
+        let unconfirmed: boolean | null = null;
 
         const mempoolTx = memPool[outpoint.txid];
         if (mempoolTx) {
-          prevout = mempoolTx.vout[outpoint.vout];
-          tx = mempoolTx;
+          if (outpoint.vout < mempoolTx.vout.length) {
+            prevout = mempoolTx.vout[outpoint.vout];
+            unconfirmed = true;  
+          }
         } else {
           const rawPrevout = await bitcoinClient.getTxOut(outpoint.txid, outpoint.vout, false);
           if (rawPrevout) {
@@ -858,11 +861,12 @@ class BitcoinRoutes {
               scriptpubkey_type: transactionUtils.translateScriptPubKeyType(rawPrevout.scriptPubKey.type),
               scriptpubkey_address: rawPrevout.scriptPubKey && rawPrevout.scriptPubKey.address ? rawPrevout.scriptPubKey.address : '',
             };
+            unconfirmed = false;
           }
         }
 
         if (prevout) {
-          result[i] = { prevout, tx };
+          result[i] = { prevout, unconfirmed };
         }
       }
 
@@ -872,6 +876,30 @@ class BitcoinRoutes {
       handleError(req, res, 500, e instanceof Error ? e.message : e);
     }
   }
+
+  private getCpfpLocalTx(req: Request, res: Response) {
+    try {
+      const tx = req.body;
+
+      if (
+        !tx || typeof tx !== "object" ||
+        !tx.txid || typeof tx.txid !== "string" ||
+        typeof tx.weight !== "number" ||
+        typeof tx.sigops !== "number" ||
+        typeof tx.fee !== "number" ||
+        !Array.isArray(tx.vin) ||
+        !Array.isArray(tx.vout)
+      ) {
+        return res.status(400).json({ message: 'Invalid transaction format: missing or incorrect fields' });
+      }
+
+      const cpfpInfo = calculateLocalTxCpfp(tx, mempool.getMempool());
+      res.json(cpfpInfo);
+
+    } catch (e) {
+      handleError(req, res, 500, e instanceof Error ? e.message : e);
+    }
+  }
 }
 
 export default new BitcoinRoutes();

backend/src/api/cpfp.ts

@@ -222,6 +222,34 @@ export function calculateMempoolTxCpfp(tx: MempoolTransactionExtended, mempool:
   };
 }
 
+
+/**
+ * Takes an unbroadcasted transaction and a copy of the current mempool, and calculates an estimate
+ * of the CPFP data if the transaction were to enter the mempool. This only returns potential ancerstors 
+ * and effective fee rate, and does not update the CPFP data of other transactions in the cluster.
+ */
+export function calculateLocalTxCpfp(tx: MempoolTransactionExtended, mempool: { [txid: string]: MempoolTransactionExtended }): CpfpInfo {
+  const ancestorMap = new Map<string, GraphTx>();
+  const graphTx = convertToGraphTx(tx, memPool.getSpendMap());
+  ancestorMap.set(tx.txid, graphTx);
+
+  const allRelatives = expandRelativesGraph(mempool, ancestorMap, memPool.getSpendMap());
+  const relativesMap = initializeRelatives(allRelatives);
+  const cluster = calculateCpfpCluster(tx.txid, relativesMap);
+
+  let totalVsize = 0;
+  let totalFee = 0;
+  for (const tx of cluster.values()) {
+    totalVsize += tx.vsize;
+    totalFee += tx.fees.base;
+  }
+
+  return {
+    ancestors: Array.from(cluster.get(tx.txid)?.ancestors.values() || []).map(ancestor => ({ txid: ancestor.txid, weight: ancestor.weight, fee: ancestor.fees.base })),
+    effectiveFeePerVsize: totalFee / totalVsize
+  }
+}
+
 /**
    * Given a root transaction and a list of in-mempool ancestors,
    * Calculate the CPFP cluster