Show the spending transaction of spent outputs

app/api/electrumAddressApi.js

@@ -353,6 +353,58 @@ function lookupTxBlockHash(txid) {
 	});
 }
 
+// Lookup the spending transaction and height of a given transaction output. Only works with Electrum 1.5 protocol, ElectRS 0.9.0 does not implement subscriptions
+// but can return the transaction spending the given outpoint
+function lookupOutpointsTx(outpoints) {
+	if (electrumClients.length == 0) {
+		return Promise.reject({ error: "Not supported by Electrum 1.4", userText: noConnectionsErrorText });
+	}
+
+	if (outpoints.length == 0) {
+		return Promise.resolve(null);
+	}
+	return runOnAllServers(function(electrumClient) {
+		return new Promise((resolve, reject) => {
+			let contents = [];
+			let arguments_far_calls = {};
+			for (let outpoint of outpoints) {
+				const id = ++electrumClient.id;
+				const request = utils.makeRequest('blockchain.outpoint.subscribe', outpoint, id);
+				contents.push(request);
+				arguments_far_calls[id] = outpoint;
+			}
+			const content = '[' + contents.join(',') + ']';
+			const promise = utils.createPromiseResultBatch(resolve, reject, arguments_far_calls);
+			electrumClient.callback_message_queue[electrumClient.id] = promise;
+			electrumClient.conn.write(content + '\n');
+		});
+	}).then(function(results) {
+		runOnAllServers(function(electrumClient) {
+			return new Promise((resolve, reject) => {
+                        	let contents = [];
+                        	let arguments_far_calls = {};
+                        	for (let outpoint of outpoints) {
+                        	       	const id = ++electrumClient.id;
+                               		const request = utils.makeRequest('blockchain.outpoint.unsubscribe', outpoint, id);
+                               		contents.push(request);
+					arguments_far_calls[id] = outpoint;
+				}
+                        	const content = '[' + contents.join(',') + ']';
+				const promise = utils.createPromiseResultBatch(resolve, reject, arguments_far_calls);
+                        	electrumClient.callback_message_queue[electrumClient.id] = promise;
+                        	electrumClient.conn.write(content + '\n');
+			});
+		});
+		const spend_infos = results[0].result;
+		if (results.slice(1).every(({ result }) => result == spend_infos)) {
+                        return spend_infos;
+                } else {
+                        return Promise.reject({conflictedResults:results});
+                }
+	});
+}
+
+
 function logStats(cmd, dt, success) {
 	if (!global.electrumStats.rpc[cmd]) {
 		global.electrumStats.rpc[cmd] = {count:0, time:0, successes:0, failures:0};
@@ -380,5 +432,6 @@ module.exports = {
 	connectToServers: connectToServers,
 	getAddressDetails: getAddressDetails,
 	lookupTxBlockHash: lookupTxBlockHash,
+	lookupOutpointsTx: lookupOutpointsTx,
 };
 

app/utils.js

@@ -1167,6 +1167,28 @@ function bip32Addresses(extPubkey, addressType, account, limit=10, offset=0) {
 	return addresses;
 }
 
+function createPromiseResultBatch(resolve, reject, argz) {
+	return (err, result) => {
+		if (result && result[0] && result[0].id) {
+			// this is a batch request response
+			for (let r of result) {
+				r.param = argz[r.id];
+			}
+		}
+		if (err) reject(err);
+		else resolve(result);
+	};
+};
+
+function makeRequest(method, params, id) {
+	return JSON.stringify({
+		jsonrpc: '2.0',
+		method: method,
+		params: params,
+		id: id,
+	});
+};
+
 module.exports = {
 	reflectPromise: reflectPromise,
 	redirectToConnectPageIfNeeded: redirectToConnectPageIfNeeded,
@@ -1220,5 +1242,7 @@ module.exports = {
 	getVoutAddress: getVoutAddress,
 	getVoutAddresses: getVoutAddresses,
 	xpubChangeVersionBytes: xpubChangeVersionBytes,
-	bip32Addresses: bip32Addresses
+	bip32Addresses: bip32Addresses,
+	createPromiseResultBatch: createPromiseResultBatch,
+	makeRequest: makeRequest,
 };

routes/baseRouter.js

@@ -26,6 +26,7 @@ const coins = require("./../app/coins.js");
 const config = require("./../app/config.js");
 const coreApi = require("./../app/api/coreApi.js");
 const addressApi = require("./../app/api/addressApi.js");
+const electrumAddressApi = require("./../app/api/electrumAddressApi.js");
 const rpcApi = require("./../app/api/rpcApi.js");
 const btcQuotes = require("./../app/coins/btcQuotes.js");
 
@@ -1362,6 +1363,61 @@ router.get("/tx/:transactionId@:blockHeight", asyncHandler(async (req, res, next
 	next();
 }));
 
+router.get("/outpoint/:transactionId-:vout", asyncHandler(async (req, res, next) => {
+	if ((config.addressApi == "electrum" || config.addressApi == "electrumx")  && config.electrumTxIndex) {
+		try {
+			var txid = utils.asHash(req.params.transactionId);
+			var vout = parseInt(req.params.vout);
+			var outpoint = [txid, vout];
+
+			const spent_outpoints = await electrumAddressApi.lookupOutpointsTx([outpoint]);
+			const spending_tx = spent_outpoints[0].result;
+
+			if (spending_tx.spender_txhash == undefined) {
+				res.locals.userMessageMarkdown = `Outpoint **${txid}:${vout}** unspent`;
+				req.url = "/tx/" + req.params.transactionId + `#output-${vout}`;
+				next();
+			} else {
+				var diff_height = "in the mempool";
+				if (spending_tx.spender_height > 0) {
+					diff_height = `after ${spending_tx.spender_height - spending_tx.height} block`
+					if (spending_tx.spender_height - spending_tx.height > 1) {
+						diff_height += `s`
+					}
+				}
+				res.locals.userMessageMarkdown = `Outpoint **${txid}:${vout}** spent by this transaction ` + diff_height;
+				req.url = "/tx/" + spending_tx.spender_txhash;
+				next();
+			}
+		} catch (err) {
+			if (global.prunedBlockchain && res.locals.blockHeight && res.locals.blockHeight < global.pruneHeight) {
+                                // Failure to load tx here is expected and a full description of the situation is given to the user
+                                // in the UI. No need to also show an error userMessage here.
+
+			} else if (!global.txindexAvailable) {
+				res.locals.noTxIndexMsg = noTxIndexMsg;
+
+                                // As above, failure to load the tx is expected here and good user feedback is given in the UI.
+                                // No need for error userMessage.
+
+			} else {
+				res.locals.userMessageMarkdown = `Outpoint not found: txid=**${txid}**, vout=**${vout}**`;
+			}
+
+
+
+			utils.logError("1237y4ewssgt", err);
+
+			res.render("transaction");
+
+			next();
+		}
+	} else {
+		req.url = "/tx/" + req.params.transactionId;
+
+		next();
+	}
+}));
 
 router.get("/tx/:transactionId", asyncHandler(async (req, res, next) => {
 	try {
@@ -1433,6 +1489,32 @@ router.get("/tx/:transactionId", asyncHandler(async (req, res, next) => {
 
 		await Promise.all(promises);
 
+		// Electrs 0.9.0 support spending transaction lookup for an outpoint
+		if ((config.addressApi == "electrum" || config.addressApi == "electrumx")  && config.electrumTxIndex) {
+			if (res.locals.utxos.length > 200) {
+				res.locals.spendings = null;
+			} else {
+				let outpoints = [];
+				for (const vout in tx.vout) {
+					if (res.locals.utxos[vout] == null) {
+						outpoints.push([txid, parseInt(vout)]);
+					}
+				}
+				const spent_outpoints = await electrumAddressApi.lookupOutpointsTx(outpoints);
+				let spendings_status = [];
+				let spent_idx = 0;
+				for (const vout in tx.vout) {
+					if (res.locals.utxos[vout] == null) {
+						spendings_status.push(spent_outpoints[spent_idx].result);
+						++spent_idx;
+					} else {
+						spendings_status.push(false)
+					}
+				}
+				res.locals.spendings = spendings_status
+			}
+		}
+
 		if (global.specialTransactions && global.specialTransactions[txid]) {
 			let funInfo = global.specialTransactions[txid];
 

views/includes/transaction-io-details.pug

@@ -241,6 +241,10 @@ mixin outputValueDisplay(vout, voutIndex)
 				- hiddenRow = true;
 				- hiddenRowCount++;
 
+			- var spent = false;
+			if (false && config.electrumServers && config.electrumServers.length > 0)
+				- spent = electrumAddressApi.lookupOutpointTx(vout, voutIndex)
+
 			div(data-txid=tx.txid, class=(hiddenRow ? "d-none" : ""))
 				.clearfix.mb-0.mb-sm-2.mb-md-0
 					a.xs-hidden.d-none.d-sm-inline.badge.card-highlight.border.text-decoration-none.fw-normal.me-2(data-bs-toggle="tooltip", title=`Output #${voutIndex.toLocaleString()}`, style="white-space: nowrap;")
@@ -275,7 +279,23 @@ mixin outputValueDisplay(vout, voutIndex)
 							span.d-none.d-sm-inline
 								+darkBadge
 									span(title=`Output Type: ${utils.outputTypeName(vout.scriptPubKey.type)}`, data-bs-toggle="tooltip") #{utils.outputTypeAbbreviation(vout.scriptPubKey.type)}
-
+							if (spendings === undefined)
+								span.mt-1 
+								a(href=`./outpoint/${tx.txid}-${voutIndex}`) Outpoint Status
+							else if (spendings)
+								- var spending_vout = spendings[voutIndex];
+								if (spending_vout  && spending_vout.spender_txhash)
+									span.mt-1 spent by 
+									a(href=`./tx/${spending_vout.spender_txhash}`) #{utils.ellipsizeMiddle(spending_vout.spender_txhash,9)}
+									if (spending_vout.spender_height > 0 && spending_vout.spender_height > spending_vout.height)
+										span  #{spending_vout.spender_height - spending_vout.height} blocks later
+									else if (spending_vout.spender_height <= 0)
+										span  in the mempool
+									else
+										span  in the same block
+							else if (spendings === null && utxos[voutIndex] == null)
+								span.mt-1 spent by 
+								a(href=`./outpoint/${txid}-${voutIndex}`) this transaction
 
 
 						if (voutAddresses.length == 0)
@@ -294,7 +314,6 @@ mixin outputValueDisplay(vout, voutIndex)
 									+darkBadge
 										span(title=`Output Type: ${utils.outputTypeName(vout.scriptPubKey.type)}`, data-bs-toggle="tooltip") #{utils.outputTypeAbbreviation(vout.scriptPubKey.type)}
 
-
 					span.ms-2.float-end
 						+outputValueDisplay(vout, voutIndex)