smart coin selection.

lib/http/server.js

@@ -311,6 +311,22 @@ HTTPServer.prototype._init = function _init() {
       enforce(util.isUInt32(options.blocks), 'Blocks must be a number.');
     }
 
+    if (params.selection != null) {
+      options.selection = params.selection;
+      enforce(typeof options.selection === 'string',
+        'selection must be a string.');
+    }
+
+    if (params.smart != null) {
+      if (typeof params.smart === 'string') {
+        options.smart = Boolean(params.smart);
+      } else {
+        options.smart = params.smart;
+        enforce(typeof options.smart === 'boolean',
+          'smart must be a boolean.');
+      }
+    }
+
     if (params.subtractFee != null) {
       if (typeof params.subtractFee === 'number') {
         options.subtractFee = params.subtractFee;

lib/wallet/txdb.js

@@ -379,7 +379,7 @@ TXDB.prototype.removeInput = function removeInput(tx, index) {
  * @returns {Boolean}
  */
 
-TXDB.prototype.resolveInput = co(function* resolveInput(tx, index, height, path) {
+TXDB.prototype.resolveInput = co(function* resolveInput(tx, index, height, path, own) {
   var hash = tx.hash('hex');
   var spent = yield this.getSpent(hash, index);
   var stx, credit;
@@ -399,6 +399,7 @@ TXDB.prototype.resolveInput = co(function* resolveInput(tx, index, height, path)
 
   // Crete the credit and add the undo coin.
   credit = Credit.fromTX(tx, index, height);
+  credit.own = own;
 
   this.spendCredit(credit, stx.tx, spent.index);
 
@@ -801,6 +802,7 @@ TXDB.prototype.insert = co(function* insert(wtx, block) {
   var hash = wtx.hash;
   var height = block ? block.height : -1;
   var details = new Details(this, wtx, block);
+  var own = false;
   var updated = false;
   var i, input, output, coin;
   var prevout, credit, path, account;
@@ -878,6 +880,7 @@ TXDB.prototype.insert = co(function* insert(wtx, block) {
       }
 
       updated = true;
+      own = true;
     }
   }
 
@@ -893,12 +896,13 @@ TXDB.prototype.insert = co(function* insert(wtx, block) {
 
     // Attempt to resolve an input we
     // did not know was ours at the time.
-    if (yield this.resolveInput(tx, i, height, path)) {
+    if (yield this.resolveInput(tx, i, height, path, own)) {
       updated = true;
       continue;
     }
 
     credit = Credit.fromTX(tx, i, height);
+    credit.own = own;
 
     this.pending.coin++;
     this.pending.unconfirmed += output.value;
@@ -2809,6 +2813,7 @@ function Credit(coin, spent) {
 
   this.coin = coin || new Coin();
   this.spent = spent || false;
+  this.own = false;
 }
 
 /**
@@ -2821,6 +2826,12 @@ Credit.prototype.fromRaw = function fromRaw(data) {
   var br = new BufferReader(data);
   this.coin.fromReader(br);
   this.spent = br.readU8() === 1;
+  this.own = true;
+
+  // Note: soft-fork
+  if (br.left() > 0)
+    this.own = br.readU8() === 1;
+
   return this;
 };
 
@@ -2840,7 +2851,7 @@ Credit.fromRaw = function fromRaw(data) {
  */
 
 Credit.prototype.getSize = function getSize() {
-  return this.coin.getSize() + 1;
+  return this.coin.getSize() + 2;
 };
 
 /**
@@ -2853,6 +2864,7 @@ Credit.prototype.toRaw = function toRaw() {
   var bw = new StaticWriter(size);
   this.coin.toWriter(bw);
   bw.writeU8(this.spent ? 1 : 0);
+  bw.writeU8(this.own ? 1 : 0);
   return bw.render();
 };
 
@@ -2867,6 +2879,7 @@ Credit.prototype.toRaw = function toRaw() {
 Credit.prototype.fromTX = function fromTX(tx, index, height) {
   this.coin.fromTX(tx, index, height);
   this.spent = false;
+  this.own = false;
   return this;
 };
 

lib/wallet/wallet.js

@@ -1421,15 +1421,17 @@ Wallet.prototype._fund = co(function* fund(mtx, options) {
   if (!account.initialized)
     throw new Error('Account is not initialized.');
 
-  coins = yield this.getCoins(options.account);
-
   rate = options.rate;
 
   if (rate == null)
     rate = yield this.db.estimateFee();
 
-  // Don't use any locked coins.
+  if (options.smart) {
-  coins = this.txdb.filterLocked(coins);
+    coins = yield this.getSmartCoins(options.account);
+  } else {
+    coins = yield this.getCoins(options.account);
+    coins = this.txdb.filterLocked(coins);
+  }
 
   yield mtx.fund(coins, {
     selection: options.selection,
@@ -2373,6 +2375,58 @@ Wallet.prototype.getCoins = co(function* getCoins(acct) {
   return yield this.txdb.getCoins(account);
 });
 
+/**
+ * Get all available credits.
+ * @param {(String|Number)?} account
+ * @returns {Promise} - Returns {@link Credit}[].
+ */
+
+Wallet.prototype.getCredits = co(function* getCredits(acct) {
+  var account = yield this.ensureIndex(acct);
+  return yield this.txdb.getCredits(account);
+});
+
+/**
+ * Get "smart" coins.
+ * @param {(String|Number)?} account
+ * @returns {Promise} - Returns {@link Coin}[].
+ */
+
+Wallet.prototype.getSmartCoins = co(function* getSmartCoins(acct) {
+  var credits = yield this.getCredits(acct);
+  var coins = [];
+  var i, credit, coin;
+
+  for (i = 0; i < credits.length; i++) {
+    credit = credits[i];
+    coin = credit.coin;
+
+    if (credit.spent)
+      continue;
+
+    if (this.txdb.isLocked(coin))
+      continue;
+
+    // Always used confirmed coins.
+    if (coin.height !== -1) {
+      coins.push(coin);
+      continue;
+    }
+
+    // Use unconfirmed only if they were
+    // created as a result of one of our
+    // _own_ transactions. i.e. they're
+    // not low-fee and not in danger of
+    // being double-spent by a bad actor.
+    if (!credit.own)
+      continue;
+
+    coins.push(coin);
+  }
+
+  return coins;
+});
+
 /**
  * Get all pending/unconfirmed transactions.
  * @param {(String|Number)?} acct

test/wallet-test.js

@@ -930,7 +930,7 @@ describe('Wallet', function() {
     assert(t2.verify());
   }));
 
-  it('should fill tx with inputs with subtract fee', co(function* () {
+  it('should fill tx with inputs with subtract fee (1)', co(function* () {
     var w1 = yield walletdb.create();
     var w2 = yield walletdb.create();
     var t1, t2;
@@ -959,7 +959,7 @@ describe('Wallet', function() {
     assert.equal(t2.getFee(), 10000);
   }));
 
-  it('should fill tx with inputs with subtract fee', co(function* () {
+  it('should fill tx with inputs with subtract fee (2)', co(function* () {
     var w1 = yield walletdb.create();
     var w2 = yield walletdb.create();
     var options, t1, t2;
@@ -993,6 +993,100 @@ describe('Wallet', function() {
     assert.equal(t2.getFee(), 10000);
   }));
 
+  it('should fill tx with smart coin selection', co(function* () {
+    var w1 = yield walletdb.create();
+    var w2 = yield walletdb.create();
+    var found = false;
+    var total = 0;
+    var i, options, t1, t2, t3, block, coins, coin;
+
+    // Coinbase
+    t1 = new MTX();
+    t1.addInput(dummy());
+    t1.addOutput(w1.getAddress(), 5460);
+    t1.addOutput(w1.getAddress(), 5460);
+    t1.addOutput(w1.getAddress(), 5460);
+    t1.addOutput(w1.getAddress(), 5460);
+    t1 = t1.toTX();
+
+    yield walletdb.addTX(t1);
+
+    // Coinbase
+    t2 = new MTX();
+    t2.addInput(dummy());
+    t2.addOutput(w1.getAddress(), 5460);
+    t2.addOutput(w1.getAddress(), 5460);
+    t2.addOutput(w1.getAddress(), 5460);
+    t2.addOutput(w1.getAddress(), 5460);
+    t2 = t2.toTX();
+
+    block = nextBlock();
+
+    yield walletdb.addBlock(block, [t2]);
+
+    coins = yield w1.getSmartCoins();
+    assert.equal(coins.length, 4);
+
+    for (i = 0; i < coins.length; i++) {
+      coin = coins[i];
+      assert.equal(coin.height, block.height);
+    }
+
+    // Create a change output for ourselves.
+    yield w1.send({
+      subtractFee: true,
+      rate: 1000,
+      depth: 1,
+      outputs: [{ address: w2.getAddress(), value: 1461 }]
+    });
+
+    coins = yield w1.getSmartCoins();
+    assert.equal(coins.length, 4);
+
+    for (i = 0; i < coins.length; i++) {
+      coin = coins[i];
+      if (coin.height === -1) {
+        assert(!found);
+        assert(coin.value < 5460);
+        found = true;
+      } else {
+        assert.equal(coin.height, block.height);
+      }
+      total += coin.value;
+    }
+
+    assert(found);
+
+    // Use smart selection
+    options = {
+      subtractFee: true,
+      smart: true,
+      rate: 10000,
+      outputs: [{ address: w2.getAddress(), value: total }]
+    };
+
+    t3 = yield w1.createTX(options);
+    assert.equal(t3.inputs.length, 4);
+
+    found = false;
+    for (i = 0; i < t3.inputs.length; i++) {
+      coin = t3.view.getCoin(t3.inputs[i]);
+      if (coin.height === -1) {
+        assert(!found);
+        assert(coin.value < 5460);
+        found = true;
+      } else {
+        assert.equal(coin.height, block.height);
+      }
+    }
+
+    assert(found);
+
+    yield w1.sign(t3);
+
+    assert(t3.verify());
+  }));
+
   it('should get range of txs', co(function* () {
     var w = wallet;
     var txs = yield w.getRange({ start: util.now() - 1000 });