From 6194c66d8fe39fa1cbc8cf673ffdebfbb3c12cb5 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Sat, 26 Mar 2016 03:17:54 -0700
Subject: [PATCH] mempool work. accurate reject messages.

---
 lib/bcoin/chain.js              |  60 +++--
 lib/bcoin/ldb.js                |  88 +++++--
 lib/bcoin/mempool.js            | 431 +++++++++++++++++++++++++-------
 lib/bcoin/mtx.js                |   2 +-
 lib/bcoin/peer.js               |   4 +-
 lib/bcoin/pool.js               |  11 +-
 lib/bcoin/protocol/constants.js |   7 +-
 lib/bcoin/protocol/framer.js    |   6 +-
 lib/bcoin/tx.js                 |  29 ++-
 lib/bcoin/txdb.js               | 120 ++++-----
 lib/bcoin/walletdb.js           |   1 -
 11 files changed, 537 insertions(+), 222 deletions(-)

diff --git a/lib/bcoin/chain.js b/lib/bcoin/chain.js
index 2b2a66ec..ba60c3f2 100644
--- a/lib/bcoin/chain.js
+++ b/lib/bcoin/chain.js
@@ -377,7 +377,8 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
   }
 
   if (!block.verify(ret)) {
-    self.emit('verify-error', block, ret.reason, ret.score, peer);
+    self.emit('verify-error',
+      block, 'invalid', ret.reason, ret.score, peer);
     return done(null, false);
   }
 
@@ -401,13 +402,15 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
     // Ensure the timestamp is correct
     if (block.ts <= medianTime) {
       utils.debug('Block time is lower than median: %s', block.rhash);
-      self.emit('verify-error', block, 'time-too-old', 0, peer);
+      self.emit('verify-error',
+        block, 'invalid', 'time-too-old', 0, peer);
       return done(null, false);
     }
 
     if (block.bits !== self.getTarget(prev, block)) {
       utils.debug('Block is using wrong target: %s', block.rhash);
-      self.emit('verify-error', block, 'bad-diffbits', 100, peer);
+      self.emit('verify-error',
+        block, 'invalid', 'bad-diffbits', 100, peer);
       return done(null, false);
     }
 
@@ -426,7 +429,8 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
     // once the majority of blocks are using it.
     if (block.version < 2 && prev.isOutdated(2)) {
       utils.debug('Block is outdated (v2): %s', block.rhash);
-      self.emit('verify-error', block, 'bad-version', 0, peer);
+      self.emit('verify-error',
+        block, 'obsolete', 'bad-version', 0, peer);
       return done(null, false);
     }
 
@@ -434,7 +438,8 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
     // once the majority of blocks are using it.
     if (block.version < 3 && prev.isOutdated(3)) {
       utils.debug('Block is outdated (v3): %s', block.rhash);
-      self.emit('verify-error', block, 'bad-version', 0, peer);
+      self.emit('verify-error',
+        block, 'obsolete', 'bad-version', 0, peer);
       return done(null, false);
     }
 
@@ -442,7 +447,8 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
     // once the majority of blocks are using it.
     if (block.version < 4 && prev.isOutdated(4)) {
       utils.debug('Block is outdated (v4): %s', block.rhash);
-      self.emit('verify-error', block, 'bad-version', 0, peer);
+      self.emit('verify-error',
+        block, 'obsolete', 'bad-version', 0, peer);
       return done(null, false);
     }
 
@@ -451,7 +457,8 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
     if (network.segwitHeight !== -1 && height >= network.segwitHeight) {
       if (block.version < 5 && prev.isOutdated(5)) {
         utils.debug('Block is outdated (v5): %s', block.rhash);
-        self.emit('verify-error', block, 'bad-version', 0, peer);
+        self.emit('verify-error',
+          block, 'obsolete', 'bad-version', 0, peer);
         return done(null, false);
       }
     }
@@ -493,7 +500,8 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
     if (coinbaseHeight) {
       if (block.getCoinbaseHeight() !== height) {
         utils.debug('Block has bad coinbase height: %s', block.rhash);
-        self.emit('verify-error', block, 'bad-cb-height', 100, peer);
+        self.emit('verify-error',
+          block, 'invalid', 'bad-cb-height', 100, peer);
         return done(null, false);
       }
     }
@@ -501,13 +509,15 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
     if (block.version >= 5 && segwit) {
       if (block.commitmentHash !== block.getCommitmentHash()) {
         utils.debug('Block failed witnessroot test: %s', block.rhash);
-        self.emit('verify-error', block, 'bad-blk-wit-length', 100, peer);
+        self.emit('verify-error',
+          block, 'invalid', 'bad-blk-wit-length', 100, peer);
         return done(null, false);
       }
     } else {
       if (block.hasWitness()) {
         utils.debug('Unexpected witness data found: %s', block.rhash);
-        self.emit('verify-error', block, 'unexpected-witness', 100, peer);
+        self.emit('verify-error',
+          block, 'invalid', 'unexpected-witness', 100, peer);
         return done(null, false);
       }
     }
@@ -523,7 +533,8 @@ Chain.prototype._verify = function _verify(block, prev, peer, callback) {
       // regards to nSequence and nLockTime.
       if (!tx.isFinal(height, ts)) {
         utils.debug('TX is not final: %s (%s)', block.rhash, i);
-        self.emit('verify-error', block, 'bad-txns-nonfinal', 10, peer);
+        self.emit('verify-error',
+          block, 'invalid', 'bad-txns-nonfinal', 10, peer);
         return done(null, false);
       }
     }
@@ -557,7 +568,8 @@ Chain.prototype._checkDuplicates = function _checkDuplicates(block, prev, peer,
       if (result) {
         utils.debug('Block is overwriting txids: %s', block.rhash);
         if (!(network.type === 'main' && (height === 91842 || height === 91880))) {
-          self.emit('verify-error', block, 'bad-txns-BIP30', 100, peer);
+          self.emit('verify-error',
+            block, 'invalid', 'bad-txns-BIP30', 100, peer);
           return next(null, false);
         }
       }
@@ -606,7 +618,8 @@ Chain.prototype._checkInputs = function _checkInputs(block, prev, flags, peer, c
 
       if (sigops > constants.script.maxBlockSigops) {
         utils.debug('Block has too many sigops: %s', block.rhash);
-        self.emit('verify-error', block, 'bad-blk-sigops', 100, peer);
+        self.emit('verify-error',
+          block, 'invalid', 'bad-blk-sigops', 100, peer);
         return callback(null, false);
       }
 
@@ -629,7 +642,8 @@ Chain.prototype._checkInputs = function _checkInputs(block, prev, flags, peer, c
             utils.revHex(input.prevout.hash) + '/' + input.prevout.index);
           if (height < network.checkpoints.lastHeight)
             throw new Error('BUG: Spent inputs in historical data!');
-          self.emit('verify-error', block, 'bad-txns-inputs-missingorspent', 100, peer);
+          self.emit('verify-error',
+            block, 'invalid', 'bad-txns-inputs-missingorspent', 100, peer);
           return callback(null, false);
         }
 
@@ -682,7 +696,8 @@ Chain.prototype._checkReward = function _checkReward(block) {
     actual.iadd(block.txs[i].getFee());
 
   if (claimed.cmp(actual) > 0) {
-    self.emit('verify-error', block, 'bad-cb-amount', 100, peer);
+    self.emit('verify-error',
+      block, 'invalid', 'bad-cb-amount', 100, peer);
     return false;
   }
 
@@ -974,7 +989,8 @@ Chain.prototype.add = function add(initial, peer, callback, force) {
             chain: !!self.invalid[prevHash]
           }, peer);
           self.invalid[hash] = true;
-          self.emit('verify-error', block, 'duplicate', 0, peer);
+          self.emit('verify-error',
+            block, 'duplicate', 'duplicate', 0, peer);
           return done();
         }
 
@@ -990,7 +1006,8 @@ Chain.prototype.add = function add(initial, peer, callback, force) {
             seen: false,
             chain: false
           }, peer);
-          self.emit('verify-error', block, ret.reason, ret.score, peer);
+          self.emit('verify-error',
+            block, 'invalid', ret.reason, ret.score, peer);
           return done();
         }
 
@@ -1024,7 +1041,8 @@ Chain.prototype.add = function add(initial, peer, callback, force) {
             seen: true
           }, peer);
 
-          self.emit('verify-error', block, 'bad-prevblk', 0, peer);
+          self.emit('verify-error',
+            block, 'invalid', 'bad-prevblk', 0, peer);
 
           return done();
         }
@@ -1048,7 +1066,8 @@ Chain.prototype.add = function add(initial, peer, callback, force) {
             hash: hash,
             seen: false
           }, peer);
-          self.emit('verify-error', block, 'bad-prevblk', 0, peer);
+          self.emit('verify-error',
+            block, 'invalid', 'bad-prevblk', 0, peer);
           return done();
         }
 
@@ -1078,7 +1097,8 @@ Chain.prototype.add = function add(initial, peer, callback, force) {
               checkpoint: true
             }, peer);
 
-            self.emit('verify-error', block, 'checkpoint mismatch', 100, peer);
+            self.emit('verify-error',
+              block, 'checkpoint', 'checkpoint mismatch', 100, peer);
 
             return done();
           }
diff --git a/lib/bcoin/ldb.js b/lib/bcoin/ldb.js
index 1ed24877..3eddea3f 100644
--- a/lib/bcoin/ldb.js
+++ b/lib/bcoin/ldb.js
@@ -10,34 +10,17 @@ var utils = bcoin.utils;
 var network = bcoin.protocol.network;
 var db = {};
 
-module.exports = function ldb(name, options) {
-  var file = bcoin.prefix + '/' + name + '-' + network.type + '.db';
-  var backend = typeof options.db === 'string'
-    ? options.db
-    : process.env.BCOIN_DB;
+/**
+ * LDB
+ */
+
+function ldb(name, options) {
+  var file = getLocation(name);
 
   if (!db[file]) {
     if (!options)
       options = {};
 
-    if (!backend || backend === 'leveldb')
-      backend = 'leveldown';
-    else if (backend === 'rocksdb')
-      backend = 'rocksdown';
-    else if (backend === 'lmdb')
-      backend = 'lmdb';
-    else if (backend === 'memory')
-      backend = 'memdown';
-
-    if (bcoin.isBrowser && backend !== 'memdown') {
-      backend = require('level-js');
-    } else {
-      if (backend !== 'memdown')
-        bcoin.ensurePrefix();
-
-      backend = require(backend);
-    }
-
     db[file] = new LowlevelUp(file, {
       keyEncoding: 'ascii',
       valueEncoding: 'binary',
@@ -59,12 +42,57 @@ module.exports = function ldb(name, options) {
       // optimizeCompaction: 'level',
       // memtableBudget: 512 << 20,
 
-      db: backend
+      db: getBackend(options.db)
     });
   }
 
   return db[file];
-};
+}
+
+function getLocation(name) {
+  return bcoin.prefix + '/' + name + '-' + network.type + '.db';
+}
+
+function getBackend(backend) {
+  if (typeof backend !== 'string')
+    backend = process.env.BCOIN_DB;
+
+  if (!backend || backend === 'leveldb')
+    backend = 'leveldown';
+  else if (backend === 'rocksdb')
+    backend = 'rocksdown';
+  else if (backend === 'lmdb')
+    backend = 'lmdb';
+  else if (backend === 'memory')
+    backend = 'memdown';
+
+  // Require directly for browserify
+  if (backend === 'memdown')
+    return require('memdown');
+
+  if (bcoin.isBrowser)
+    return require('level-js');
+
+  bcoin.ensurePrefix();
+
+  return require(backend);
+}
+
+function destroy(name, backend, callback) {
+  var file = getLocation(name);
+
+  if (!callback) {
+    callback = backend;
+    backend = null;
+  }
+
+  backend = getBackend(backend);
+
+  if (!backend.destroy)
+    return utils.nextTick(callback);
+
+  backend.destroy(file, callback);
+}
 
 /**
  * LowlevelUp
@@ -168,3 +196,13 @@ LowlevelUp.prototype.getProperty = function getProperty(name) {
 LowlevelUp.prototype.approximateSize = function approximateSize(start, end, callback) {
   return this.binding.approximateSize(start, end, callback);
 };
+
+/**
+ * Expose
+ */
+
+exports = ldb;
+exports.LowlevelUp = LowlevelUp;
+exports.destroy = destroy;
+
+module.exports = exports;
diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index ddfe0d1a..757a51c0 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -9,6 +9,7 @@ var EventEmitter = require('events').EventEmitter;
 var bcoin = require('../bcoin');
 var bn = require('bn.js');
 var constants = bcoin.protocol.constants;
+var network = bcoin.protocol.network;
 var utils = require('./utils');
 var assert = utils.assert;
 var BufferWriter = require('./writer');
@@ -32,34 +33,20 @@ function Mempool(node, options) {
   this.node = node;
   this.chain = node.chain;
 
-  this.db = bcoin.ldb('mempool', {
-    db: 'memdown'
-  });
-
-  this.tx = new bcoin.txdb('m', this.db, {
-    indexSpent: true,
-    indexExtra: false,
-    indexAddress: false,
-    mapAddress: false,
-    verify: false
-  });
-
   this.loaded = false;
 
-  this.jobs = [];
-  this.busy = false;
+  this.locker = new bcoin.locker(this, this.add, 20 << 20);
 
-  this.pending = [];
-  this.pendingTX = {};
-  this.pendingSize = 0;
-  this.pendingLimit = 20 << 20;
-  this.locker = new bcoin.locker(this, this.add, this.pendingLimit);
+  this.db = null;
+  this.tx = null;
+  this.size = 0;
 
   this.freeCount = 0;
   this.lastTime = 0;
 
   this.limitFree = this.options.limitFree !== false;
   this.limitFreeRelay = this.options.limitFreeRelay || 15;
+  this.relayPriority = this.options.relayPriority !== false;
   this.requireStandard = this.options.requireStandard !== false;
   this.rejectInsaneFees = this.options.rejectInsaneFees !== false;
 
@@ -73,6 +60,10 @@ utils.inherits(Mempool, EventEmitter);
 Mempool.flags = constants.flags.STANDARD_VERIFY_FLAGS;
 Mempool.mandatory = constants.flags.MANDATORY_VERIFY_FLAGS;
 
+Mempool.ANCESTOR_LIMIT = 25;
+Mempool.MAX_MEMPOOL_SIZE = 300 << 20;
+Mempool.MEMPOOL_EXPIRY = 72 * 60 * 60;
+
 Mempool.prototype._lock = function _lock(func, args, force) {
   return this.locker.lock(func, args, force);
 };
@@ -83,20 +74,53 @@ Mempool.prototype.purgePending = function purgePending() {
 
 Mempool.prototype._init = function _init() {
   var self = this;
+  var unlock = this._lock(utils.nop, []);
 
-  if (this.db.loaded) {
-    this.loaded = true;
-    return;
-  }
+  bcoin.ldb.destroy('mempool', 'memdown', function(err) {
+    if (err) {
+      unlock();
+      return self.emit('error', err);
+    }
 
-  this.db.once('open', function() {
-    self.loaded = true;
-    self.emit('open');
+    self.db = bcoin.ldb('mempool', {
+      db: 'memdown'
+    });
+
+    self.tx = new bcoin.txdb('m', self.db, {
+      indexExtra: false,
+      indexAddress: false,
+      mapAddress: false,
+      verify: false
+    });
+
+    self.db.open(function(err) {
+      if (err) {
+        unlock();
+        return self.emit('error', err);
+      }
+      self.dynamicMemoryUsage(function(err, size) {
+        if (err)
+          self.emit('error', err);
+        else
+          self.size = size;
+
+        unlock();
+        self.loaded = true;
+        self.emit('open');
+      });
+    });
   });
 };
 
+Mempool.prototype.dynamicMemoryUsage = function dynamicMemoryUsage(callback) {
+  return this.db.approximateSize('m', 'm~', callback);
+};
+
 Mempool.prototype.open = function open(callback) {
-  return this.db.open(callback);
+  if (this.loaded)
+    return utils.nextTick(callback);
+
+  return this.once('open', callback);
 };
 
 Mempool.prototype.addBlock = function addBlock(block, callback, force) {
@@ -107,14 +131,9 @@ Mempool.prototype.addBlock = function addBlock(block, callback, force) {
 
   callback = utils.wrap(callback, unlock);
 
-  this.open(function(err) {
-    if (err)
-      return callback(err);
-
-    utils.forEachSerial(block.txs, function(tx, next) {
-      self.tx.removeUnchecked(tx, next);
-    }, callback);
-  });
+  utils.forEachSerial(block.txs, function(tx, next) {
+    self.removeUnchecked(tx, next);
+  }, callback);
 };
 
 Mempool.prototype.removeBlock = function removeBlock(block, callback, force) {
@@ -126,10 +145,91 @@ Mempool.prototype.removeBlock = function removeBlock(block, callback, force) {
   callback = utils.wrap(callback, unlock);
 
   utils.forEachSerial(block.txs.slice().reverse(), function(tx, next) {
-    self.tx.addUnchecked(tx, next);
+    self.addUnchecked(tx, next);
   }, callback);
 };
 
+Mempool.prototype.limitMempoolSize = function limitMempoolSize(callback) {
+  var self = this;
+
+  if (this.size <= Mempool.MAX_MEMPOOL_SIZE)
+    return callback(null, true);
+
+  this.db.getRange({
+    start: 0,
+    end: utils.now() - Mempool.MEMPOOL_EXPIRY
+  }, function(err, txs) {
+    if (err)
+      return callback(err);
+
+    utils.forEachSerial(function(tx, next) {
+      self.removeUnchecked(tx, next);
+    }, function(err) {
+      if (err)
+        return callback(err);
+
+      self.purgeOrphans(function(err) {
+        if (err)
+          return callback(err);
+
+        return callback(self.size <= Mempool.MAX_MEMPOOL_SIZE);
+      });
+    });
+  });
+};
+
+Mempool.prototype.purgeOrphans = function purgeOrphans(callback) {
+  var self = this;
+  var batch = this.db.batch();
+
+  callback = utils.ensure(callback);
+
+  utils.forEachSerial(['m/D', 'm/d'], function(type, callback) {
+    var iter = self.db.iterator({
+      gte: type,
+      lte: type + '~',
+      keys: true,
+      values: false,
+      fillCache: false,
+      keyAsBuffer: false
+    });
+
+    (function next() {
+      iter.next(function(err, key, value) {
+        if (err) {
+          return iter.end(function() {
+            callback(err);
+          });
+        }
+
+        if (key === undefined)
+          return iter.end(callback);
+
+        batch.del(key);
+
+        next();
+      });
+    })();
+  }, function(err) {
+    if (err)
+      return callback(err);
+
+    batch.write(function(err) {
+      if (err)
+        return callback(err);
+
+      self.dynamicMemoryUsage(function(err, size) {
+        if (err)
+          return callback(err);
+
+        self.size = size;
+
+        return callback();
+      });
+    });
+  });
+};
+
 Mempool.prototype.get =
 Mempool.prototype.getTX = function getTX(hash, callback) {
   if (hash instanceof bcoin.tx)
@@ -197,18 +297,18 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback, force) {
   callback = utils.asyncify(callback);
 
   if (!this.checkTX(tx, peer))
-    return callback(new VerifyError('CheckTransaction failed', -1));
+    return callback(new VerifyError('invalid', 'CheckTransaction failed', -1));
 
   if (tx.isCoinbase()) {
-    peer.sendReject(tx, 'coinbase', 100);
-    return callback(new VerifyError('coinbase as individual tx', 100));
+    peer.sendReject(tx, 'invalid', 'coinbase', 100);
+    return callback(new VerifyError('invalid', 'coinbase', 100));
   }
 
   ts = utils.now();
   height = this.chain.height + 1;
 
   if (this.requireStandard && !tx.isStandard(Mempool.flags, ts, height, ret)) {
-    peer.sendReject(tx, ret.reason, 0);
+    peer.sendReject(tx, 'nonstandard', ret.reason, 0);
     return callback(new VerifyError(ret.reason, 0));
   }
 
@@ -216,33 +316,57 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback, force) {
     if (err)
       return callback(err);
 
-    if (exists)
+    if (exists) {
+      peer.sendReject(tx, 'alreadyknown', 'txn-already-in-mempool', 0);
       return callback();
+    }
 
     self.tx.isDoubleSpend(tx, function(err, doubleSpend) {
       if (err)
         return callback(err);
 
       if (doubleSpend) {
-        peer.sendReject(tx, 'bad-txns-inputs-spent', 0);
-        return callback(new VerifyError('bad-txns-inputs-spent', 0));
+        peer.sendReject(tx, 'duplicate', 'bad-txns-inputs-spent', 0);
+        return callback(new VerifyError(
+          'duplicate',
+          'bad-txns-inputs-spent',
+          0));
       }
 
       self.node.fillCoin(tx, function(err) {
         if (err)
           return callback(err);
 
-        if (!tx.hasPrevout())
+        if (!tx.hasPrevout()) {
+          if (self.size > Mempool.MAX_MEMPOOL_SIZE) {
+            return callback(
+              new VerifyError('insufficientfee',
+              'mempool full',
+              0));
+          }
           return self.storeOrphan(tx, callback);
+        }
 
         self.verify(tx, function(err) {
           if (err) {
             if (err.type === 'VerifyError' && err.score >= 0)
-              peer.sendReject(tx, err.reason, err.score);
+              peer.sendReject(tx, err.code, err.reason, err.score);
             return callback(err);
           }
 
-          self.addUnchecked(tx, peer, callback);
+          self.limitMempoolSize(function(err, result) {
+            if (err)
+              return callback(err);
+
+            if (!result) {
+              return callback(
+                new VerifyError('insufficientfee',
+                'mempool full',
+                0));
+            }
+
+            self.addUnchecked(tx, peer, callback);
+          });
         });
       });
     });
@@ -255,7 +379,9 @@ Mempool.prototype.addUnchecked = function addUnchecked(tx, peer, callback) {
     if (err)
       return callback(err);
 
+    self.size += tx.getSize();
     self.emit('tx', tx);
+    self.emit('add tx', tx);
 
     utils.debug('Added tx %s to the mempool.', tx.rhash);
 
@@ -274,15 +400,40 @@ Mempool.prototype.addUnchecked = function addUnchecked(tx, peer, callback) {
   });
 };
 
+Mempool.prototype.removeUnchecked = function removeUnchecked(tx, callback) {
+  var self = this;
+  this.tx.removeUnchecked(tx, function(err) {
+    if (err)
+      return callback(err);
+    self.size -= tx.getSize();
+    self.emit('remove tx', tx);
+    return callback();
+  });
+};
+
 Mempool.prototype.verify = function verify(tx, callback) {
   var self = this;
-  var total, input, coin, i, fee, now;
+  var height = this.chain.height + 1;
+  var total, input, coin, i, fee, now, free, minFee;
 
-  if (this.requireStandard && !tx.isStandardInputs(Mempool.flags))
-    return callback(new VerifyError('TX inputs are not standard.', -1));
+  if (network.type !== 'segwit') {
+    if (tx.hasWitness())
+      return callback(new VerifyError('nonstandard', 'no-witness-yet', 0));
+  }
 
-  if (tx.getSigops(true) > constants.script.maxSigops)
-    return callback(new VerifyError('bad-txns-too-many-sigops', 0));
+  if (this.requireStandard && !tx.isStandardInputs(Mempool.flags)) {
+    return callback(new VerifyError(
+      'nonstandard',
+      'bad-txns-nonstandard-inputs',
+      0));
+  }
+
+  if (tx.getSigops(true) > constants.script.maxSigops) {
+    return callback(new VerifyError(
+      'nonstandard',
+      'bad-txns-too-many-sigops',
+      0));
+  }
 
   total = new bn(0);
   for (i = 0; i < tx.inputs.length; i++) {
@@ -290,34 +441,61 @@ Mempool.prototype.verify = function verify(tx, callback) {
     coin = input.output;
 
     if (coin.coinbase) {
-      if (this.chain.height - coin.height < constants.tx.coinbaseMaturity)
-        return callback(new VerifyError('bad-txns-premature-spend-of-coinbase', 0));
+      if (this.chain.height - coin.height < constants.tx.coinbaseMaturity) {
+        return callback(new VerifyError(
+          'invalid',
+          'bad-txns-premature-spend-of-coinbase',
+          0));
+      }
     }
 
-    if (coin.value.cmpn(0) < 0 || coin.value.cmp(constants.maxMoney) > 0)
-      return callback(new VerifyError('bad-txns-inputvalues-outofrange', 100));
+    if (coin.value.cmpn(0) < 0 || coin.value.cmp(constants.maxMoney) > 0) {
+      return callback(new VerifyError(
+        'invalid',
+        'bad-txns-inputvalues-outofrange',
+        100));
+    }
 
     total.iadd(coin.value);
   }
 
-  if (total.cmpn(0) < 0 || total.cmp(constants.maxMoney) > 0)
-    return callback(new VerifyError('bad-txns-inputvalues-outofrange', 100));
+  if (total.cmpn(0) < 0 || total.cmp(constants.maxMoney) > 0) {
+    return callback(new VerifyError(
+      'invalid',
+      'bad-txns-inputvalues-outofrange',
+      100));
+  }
 
   if (tx.getOutputValue().cmp(total) > 0)
-    return callback(new VerifyError('bad-txns-in-belowout', 100));
+    return callback(new VerifyError('invalid', 'bad-txns-in-belowout', 100));
 
   fee = total.sub(tx.getOutputValue());
 
   if (fee.cmpn(0) < 0)
-    return callback(new VerifyError('bad-txns-fee-negative', 100));
+    return callback(new VerifyError('invalid', 'bad-txns-fee-negative', 100));
 
   if (fee.cmp(constants.maxMoney) > 0)
-    return callback(new VerifyError('bad-txns-fee-outofrange', 100));
+    return callback(new VerifyError('invalid', 'bad-txns-fee-outofrange', 100));
 
-  if (this.limitFree && fee.cmp(tx.getMinFee(true)) < 0)
-    return callback(new VerifyError('insufficient fee', 0));
+  minFee = tx.getMinFee();
+  if (fee.cmp(minFee) < 0) {
+    if (this.relayPriority && fee.cmpn(0) === 0) {
+      free = tx.isFree(height);
+      if (!free) {
+        return callback(new VerifyError(
+          'insufficientfee',
+          'insufficient priority',
+          0));
+      }
+    } else {
+      return callback(new VerifyError(
+        'insufficientfee',
+        'insufficient fee',
+        0));
+    }
+  }
 
-  if (this.limitFree && fee.cmpn(tx.getMinFee()) < 0) {
+  if (this.limitFree && free) {
     now = utils.now();
 
     if (!this.lastTime)
@@ -326,33 +504,85 @@ Mempool.prototype.verify = function verify(tx, callback) {
     this.freeCount *= Math.pow(1 - 1 / 600, now - this.lastTime);
     this.lastTime = now;
 
-    if (this.freeCount > this.limitFreeRelay * 10 * 1000)
-      return callback(new VerifyError('insufficient priority', 0));
+    if (this.freeCount > this.limitFreeRelay * 10 * 1000) {
+      return callback(new VerifyError(
+        'insufficientfee',
+        'rate limited free transaction',
+        0));
+    }
 
     this.freeCount += tx.getVirtualSize();
   }
 
-  if (this.rejectInsaneFees && fee.cmpn(tx.getMinFee().muln(10000)) > 0)
-    return callback(new VerifyError('TX has an insane fee.', -1));
+  if (this.rejectInsaneFees && fee.cmp(minFee.muln(10000)) > 0)
+    return callback(new VerifyError('highfee', 'absurdly-high-fee', 0));
 
-  // Do this in the worker pool.
-  tx.verifyAsync(null, true, Mempool.flags, function(err, result) {
+  this.countAncestors(tx, function(err, count) {
     if (err)
       return callback(err);
 
-    if (!result) {
-      return tx.verifyAsync(null, true, Mempool.mandatory, function(err, result) {
-        if (err)
-          return callback(err);
-
-        if (!result)
-          return callback(new VerifyError('mandatory-script-verify-flag', 0));
-
-        return callback(new VerifyError('non-mandatory-script-verify-flag', 0));
-      });
+    if (count > Mempool.ANCESTOR_LIMIT) {
+      return callback(new VerifyError(
+        'nonstandard',
+        'too-long-mempool-chain',
+        0));
     }
 
-    return callback();
+    // Do this in the worker pool.
+    tx.verifyAsync(null, true, Mempool.flags, function(err, result) {
+      if (err)
+        return callback(err);
+
+      if (!result) {
+        return tx.verifyAsync(null, true, Mempool.mandatory, function(err, result) {
+          if (err)
+            return callback(err);
+
+          if (!result) {
+            return callback(new VerifyError(
+              'nonstandard',
+              'mandatory-script-verify-flag',
+              0));
+          }
+
+          return callback(
+            new VerifyError('nonstandard',
+            'non-mandatory-script-verify-flag',
+            0));
+        });
+      }
+
+      return callback();
+    });
+  });
+};
+
+Mempool.prototype.countAncestors = function countAncestors(tx, callback) {
+  var self = this;
+  var inputs = new Array(tx.inputs.length);
+  utils.forEachSerial(tx.inputs, function(input, next, i) {
+    inputs[i] = 0;
+    self.getTX(input.prevout.hash, function(err, tx) {
+      if (err)
+        return next(err);
+
+      if (!tx)
+        return next();
+
+      self.countAncestors(tx, function(err, max) {
+        if (err)
+          return next(err);
+
+        inputs[i] += max;
+
+        next();
+      });
+    });
+  }, function(err) {
+    if (err)
+      return callback(err);
+
+    return callback(null, inputs.sort().pop());
   });
 };
 
@@ -507,7 +737,7 @@ Mempool.prototype.resolveOrphans = function resolveOrphans(tx, callback, force)
   });
 };
 
-Mempool.prototype.getInv = function getInv(callback) {
+Mempool.prototype.getSnapshot = function getSnapshot(callback) {
   return this.tx.getAllHashes(callback);
 };
 
@@ -516,60 +746,73 @@ Mempool.prototype.checkTX = function checkTX(tx, peer) {
 };
 
 Mempool.checkTX = function checkTX(tx, peer) {
-  var i, input, output, size;
-  var total = new bn(0);
   var uniq = {};
+  var total = new bn(0);
+  var i, input, output, size;
 
   if (!peer)
     peer = DUMMY_PEER;
 
   if (tx.inputs.length === 0)
-    return peer.sendReject(tx, 'bad-txns-vin-empty', 100);
+    return peer.sendReject(tx, 'invalid', 'bad-txns-vin-empty', 100);
 
   if (tx.outputs.length === 0)
-    return peer.sendReject(tx, 'bad-txns-vout-empty', 100);
+    return peer.sendReject(tx, 'invalid', 'bad-txns-vout-empty', 100);
 
   if (tx.getVirtualSize() > constants.block.maxSize)
-    return peer.sendReject(tx, 'bad-txns-oversize', 100);
+    return peer.sendReject(tx, 'invalid', 'bad-txns-oversize', 100);
 
   for (i = 0; i < tx.outputs.length; i++) {
     output = tx.outputs[i];
+
     if (output.value.cmpn(0) < 0)
-      return peer.sendReject(tx, 'bad-txns-vout-negative', 100);
+      return peer.sendReject(tx, 'invalid', 'bad-txns-vout-negative', 100);
+
     if (output.value.cmp(constants.maxMoney) > 0)
-      return peer.sendReject(tx, 'bad-txns-vout-toolarge', 100);
+      return peer.sendReject(tx, 'invalid', 'bad-txns-vout-toolarge', 100);
+
     total.iadd(output.value);
-    if (total.cmpn(0) < 0 || total.cmp(constants.maxMoney) > 0)
-      return peer.sendReject(tx, 'bad-txns-txouttotal-toolarge', 100);
+
+    if (total.cmpn(0) < 0 || total.cmp(constants.maxMoney) > 0) {
+      return peer.sendReject(tx,
+        'invalid',
+        'bad-txns-txouttotal-toolarge',
+        100);
+    }
   }
 
   for (i = 0; i < tx.inputs.length; i++) {
     input = tx.inputs[i];
     if (uniq[input.prevout.hash])
-      return peer.sendReject(tx, 'bad-txns-inputs-duplicate', 100);
+      return peer.sendReject(tx, 'invalid', 'bad-txns-inputs-duplicate', 100);
     uniq[input.prevout.hash] = true;
   }
 
   if (tx.isCoinbase()) {
     size = tx.inputs[0].script.getSize();
     if (size < 2 || size > 100)
-      return peer.sendReject(tx, 'bad-cb-length', 100);
+      return peer.sendReject(tx, 'invalid', 'bad-cb-length', 100);
   } else {
     for (i = 0; i < tx.inputs.length; i++) {
       input = tx.inputs[i];
       if (+input.prevout.hash === 0)
-        return peer.sendReject(tx, 'bad-txns-prevout-null', 10);
+        return peer.sendReject(tx, 'invalid', 'bad-txns-prevout-null', 10);
     }
   }
 
   return true;
 };
 
-function VerifyError(reason, score) {
+/**
+ * VerifyError
+ */
+
+function VerifyError(code, reason, score) {
   Error.call(this);
   if (Error.captureStackTrace)
     Error.captureStackTrace(this, VerifyError);
   this.type = 'VerifyError';
+  this.code = code;
   this.message = reason;
   this.reason = score === -1 ? null : reason;
   this.score = score;
diff --git a/lib/bcoin/mtx.js b/lib/bcoin/mtx.js
index 25c5f1cb..c1e6f5bb 100644
--- a/lib/bcoin/mtx.js
+++ b/lib/bcoin/mtx.js
@@ -882,7 +882,7 @@ MTX.prototype.selectCoins = function selectCoins(unspent, options) {
       // Calculate max possible size after signing.
       size = tx.maxSize(options.m, options.n);
 
-      // if (newkb == null && tx.isFree(size)) {
+      // if (newkb == null && tx.isFree(this.chain.height + 1, size)) {
       //   fee = new bn(0);
       //   break;
       // }
diff --git a/lib/bcoin/peer.js b/lib/bcoin/peer.js
index d6872b2c..724131fd 100644
--- a/lib/bcoin/peer.js
+++ b/lib/bcoin/peer.js
@@ -679,8 +679,8 @@ Peer.prototype.setMisbehavior = function setMisbehavior(dos) {
   return this.pool.setMisbehavior(this, dos);
 };
 
-Peer.prototype.sendReject = function sendReject(obj, reason, dos) {
-  return this.pool.reject(this, obj, reason, dos);
+Peer.prototype.sendReject = function sendReject(obj, code, reason, dos) {
+  return this.pool.reject(this, obj, code, reason, dos);
 };
 
 /**
diff --git a/lib/bcoin/pool.js b/lib/bcoin/pool.js
index 0af8c29d..4e34a1e3 100644
--- a/lib/bcoin/pool.js
+++ b/lib/bcoin/pool.js
@@ -191,8 +191,8 @@ Pool.prototype._init = function _init() {
     }
   });
 
-  this.chain.on('verify-error', function(block, reason, score, peer) {
-    peer.sendReject(block, reason, score);
+  this.chain.on('verify-error', function(block, code, reason, score, peer) {
+    peer.sendReject(block, code, reason, score);
   });
 
   this.chain.on('fork', function(block, data, peer) {
@@ -1885,14 +1885,15 @@ Pool.prototype.isMisbehaving = function isMisbehaving(host) {
   return false;
 };
 
-Pool.prototype.reject = function reject(peer, obj, reason, dos) {
+Pool.prototype.reject = function reject(peer, obj, code, reason, dos) {
   if (dos != null)
     peer.setMisbehavior(dos);
 
-  utils.debug('Rejecting %s %s: reason=%s',
-    obj.type, obj.hash('hex'), reason);
+  utils.debug('Rejecting %s %s: ccode=%s reason=%s',
+    obj.type, obj.hash('hex'), code, reason);
 
   peer.reject({
+    ccode: code,
     reason: reason,
     data: obj.hash()
   });
diff --git a/lib/bcoin/protocol/constants.js b/lib/bcoin/protocol/constants.js
index 68d0574c..dd6e8ded 100644
--- a/lib/bcoin/protocol/constants.js
+++ b/lib/bcoin/protocol/constants.js
@@ -249,7 +249,12 @@ exports.reject = {
   nonstandard: 0x40,
   dust: 0x41,
   insufficientfee: 0x42,
-  checkpoint: 0x43
+  checkpoint: 0x43,
+  // Internal codes (NOT FOR USE ON NETWORK)
+  internal: 0x100,
+  highfee: 0x100,
+  alreadyknown: 0x101,
+  conflict: 0x102
 };
 
 exports.rejectByVal = Object.keys(exports.reject).reduce(function(out, name) {
diff --git a/lib/bcoin/protocol/framer.js b/lib/bcoin/protocol/framer.js
index 26128e87..adade16b 100644
--- a/lib/bcoin/protocol/framer.js
+++ b/lib/bcoin/protocol/framer.js
@@ -580,9 +580,13 @@ Framer.headers = function _headers(block, writer) {
 
 Framer.reject = function reject(details, writer) {
   var p = new BufferWriter(writer);
+  var ccode = details.ccode;
+
+  if (ccode >= constants.reject.internal)
+    ccode = constants.reject.invalid;
 
   p.writeVarString(details.message || '', 'ascii');
-  p.writeU8(constants.reject[details.ccode] || constants.reject.malformed);
+  p.writeU8(constants.reject[ccode] || constants.reject.invalid);
   p.writeVarString(details.reason || '', 'ascii');
   if (details.data)
     p.writeHash(details.data);
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index 9dd7be52..14b3f886 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -916,10 +916,11 @@ TX.prototype.maxSize = function maxSize() {
   return this.getVirtualSize();
 };
 
-TX.prototype.getPriority = function getPriority(size) {
-  var sum, i, input, age, height;
+TX.prototype.getPriority = function getPriority(height, size) {
+  var sum, i, input, age;
 
-  height = this.height;
+  if (height == null)
+    height = this.height;
 
   if (height === -1)
     height = null;
@@ -927,7 +928,9 @@ TX.prototype.getPriority = function getPriority(size) {
   if (!this.hasPrevout())
     return new bn(0);
 
-  size = size || this.maxSize();
+  if (size == null)
+    size = this.maxSize();
+
   sum = new bn(0);
 
   for (i = 0; i < this.inputs.length; i++) {
@@ -950,29 +953,31 @@ TX.prototype.getPriority = function getPriority(size) {
   return sum.divn(size);
 };
 
-TX.prototype.isFree = function isFree(size) {
+TX.prototype.isFree = function isFree(height, size) {
   var priority;
 
   if (!this.hasPrevout())
     return false;
 
-  size = size || this.maxSize();
+  if (height == null)
+    height = this.height;
+
+  if (size == null)
+    size = this.maxSize();
 
   if (size >= constants.tx.maxFreeSize)
     return false;
 
-  priority = this.getPriority();
+  priority = this.getPriority(height, size);
 
   return priority.cmp(constants.tx.freeThreshold) > 0;
 };
 
-TX.prototype.getMinFee = function getMinFee(allowFree, size) {
+TX.prototype.getMinFee = function getMinFee(size) {
   var fee;
 
-  size = size || this.maxSize();
-
-  if (allowFree && this.isFree(size))
-    return new bn(0);
+  if (size == null)
+    size = this.maxSize();
 
   fee = new bn(constants.tx.minFee).muln(size).divn(1000);
 
diff --git a/lib/bcoin/txdb.js b/lib/bcoin/txdb.js
index 3d6998b6..299a9d48 100644
--- a/lib/bcoin/txdb.js
+++ b/lib/bcoin/txdb.js
@@ -1546,6 +1546,7 @@ TXPool.prototype.addUnchecked = function addUnchecked(tx, callback, force) {
   batch = this.db.batch();
 
   batch.put(prefix + 't/t/' + hash, tx.toExtended());
+  batch.put(prefix + 't/s/s/' + pad32(tx.ps) + '/' + hash, DUMMY);
 
   tx.getAddresses().forEach(function(address) {
     batch.put(prefix + 't/a/' + address + '/' + hash, DUMMY);
@@ -1586,68 +1587,77 @@ TXPool.prototype.addUnchecked = function addUnchecked(tx, callback, force) {
   });
 };
 
-TXPool.prototype.removeUnchecked = function removeUnchecked(tx, callback, force) {
+TXPool.prototype.removeUnchecked = function removeUnchecked(hash, callback, force) {
   var self = this;
   var prefix = this.prefix + '/';
-  var hash = tx.hash('hex');
   var batch;
 
-  var unlock = this._lock(removeUnchecked, [tx, callback], force);
+  var unlock = this._lock(removeUnchecked, [hash, callback], force);
   if (!unlock)
     return;
 
   callback = utils.wrap(callback, unlock);
 
-  batch = this.db.batch();
+  if (hash.hash)
+    hash = hash.hash('hex');
 
-  batch.del(prefix + 't/t/' + hash);
-  batch.del(prefix + 'D/' + hash);
-
-  tx.getAddresses().forEach(function(address) {
-    batch.del(prefix + 't/a/' + address + '/' + hash);
-  });
-
-  tx.inputs.forEach(function(input) {
-    var key = input.prevout.hash + '/' + input.prevout.index;
-    var address;
-
-    if (tx.isCoinbase())
-      return;
-
-    if (!input.output)
-      return;
-
-    address = input.getAddress();
-
-    batch.del(prefix + 'u/t/' + key);
-    batch.del(prefix + 's/t/' + key);
-
-    if (address)
-      batch.del(prefix + 'u/a/' + address + '/' + key);
-  });
-
-  tx.outputs.forEach(function(output, i) {
-    var key = hash + '/' + i;
-    var address = output.getAddress();
-
-    batch.del(prefix + 'u/t/' + key);
-
-    if (address)
-      batch.del(prefix + 'u/a/' + address + '/' + key);
-  });
-
-  batch.write(function(err) {
+  this.getTX(hash, function(err, tx) {
     if (err)
       return callback(err);
-    self.emit('remove tx', tx);
-    return callback();
+
+    if (!tx)
+      return callback();
+
+    batch = self.db.batch();
+
+    batch.del(prefix + 't/t/' + hash);
+    batch.del(prefix + 't/s/s/' + pad32(tx.ps) + '/' + hash);
+    batch.del(prefix + 'D/' + hash);
+
+    tx.getAddresses().forEach(function(address) {
+      batch.del(prefix + 't/a/' + address + '/' + hash);
+    });
+
+    tx.inputs.forEach(function(input) {
+      var key = input.prevout.hash + '/' + input.prevout.index;
+      var address;
+
+      if (tx.isCoinbase())
+        return;
+
+      if (!input.output)
+        return;
+
+      address = input.getAddress();
+
+      batch.del(prefix + 'u/t/' + key);
+      batch.del(prefix + 's/t/' + key);
+
+      if (address)
+        batch.del(prefix + 'u/a/' + address + '/' + key);
+    });
+
+    tx.outputs.forEach(function(output, i) {
+      var key = hash + '/' + i;
+      var address = output.getAddress();
+
+      batch.del(prefix + 'u/t/' + key);
+
+      if (address)
+        batch.del(prefix + 'u/a/' + address + '/' + key);
+    });
+
+    batch.write(function(err) {
+      if (err)
+        return callback(err);
+      self.emit('remove tx', tx);
+      return callback();
+    });
   });
 };
 
-TXPool.prototype.zap = function zap(tip, callback, force) {
+TXPool.prototype.zap = function zap(now, age, callback, force) {
   var self = this;
-  var now = tip.ts;
-  var age = 10 * 60 * 60;
 
   var unlock = this._lock(zap, [tip, callback], force);
   if (!unlock)
@@ -1655,23 +1665,13 @@ TXPool.prototype.zap = function zap(tip, callback, force) {
 
   callback = utils.wrap(callback, unlock);
 
-  // return this.getRange(null, {
-  //   start: 0,
-  //   end: now - age
-  // }, function(err, txs) {
-  // });
-
-  this.getPending(function(err, txs) {
+  return this.getRange(null, {
+    start: 0,
+    end: now - age
+  }, function(err, txs) {
     if (err)
       return callback(err);
 
-    txs = txs.filter(function(tx) {
-      return now > tx.ps + age;
-    });
-
-    if (txs.length === 0)
-      return callback();
-
     self.fillTX(txs, function(err) {
       if (err)
         return callback(err);
diff --git a/lib/bcoin/walletdb.js b/lib/bcoin/walletdb.js
index 3bde6879..55904db7 100644
--- a/lib/bcoin/walletdb.js
+++ b/lib/bcoin/walletdb.js
@@ -98,7 +98,6 @@ WalletDB.prototype._init = function _init() {
   });
 
   this.tx = new bcoin.txdb('w', this.db, {
-    indexSpent: true,
     indexExtra: true,
     indexAddress: true,
     mapAddress: true,