From 5d9f106e2a4938028b64d21c68d73293002fb899 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Wed, 17 Feb 2016 15:30:33 -0800
Subject: [PATCH] event based system for chain error handling.

---
 lib/bcoin/chain.js   | 121 ++++++++++++++++---
 lib/bcoin/coin.js    |   2 +-
 lib/bcoin/mempool.js |   2 +-
 lib/bcoin/peer.js    |   4 +-
 lib/bcoin/pool.js    | 268 +++++++++++++------------------------------
 lib/bcoin/tx.js      |   4 +-
 6 files changed, 187 insertions(+), 214 deletions(-)

diff --git a/lib/bcoin/chain.js b/lib/bcoin/chain.js
index 6837e236..0b413099 100644
--- a/lib/bcoin/chain.js
+++ b/lib/bcoin/chain.js
@@ -39,11 +39,13 @@ function Chain(options) {
   this.request = new utils.RequestCache();
   this.loading = false;
   this.tip = null;
+  this.height = -1;
   this.mempool = options.mempool;
   this.blockdb = options.blockdb;
   this.locked = false;
   this.pending = [];
   this.orphanLimit = options.orphanLimit || 20 * 1024 * 1024;
+  this.invalid = {};
 
   this.orphan = {
     map: {},
@@ -86,6 +88,47 @@ Chain.msg = function msg(code) {
 Chain.prototype._init = function _init() {
   var self = this;
 
+  // Hook into events for debugging
+  this.on('fork', function(data, peer) {
+    var host = peer ? peer.host : 'unknown';
+    utils.debug(
+      'Fork at height %d: expected=%s received=%s checkpoint=%s peer=%s',
+      data.height,
+      utils.revHex(data.expected),
+      utils.revHex(data.received),
+      data.checkpoint,
+      host
+    );
+  });
+
+  this.on('invalid', function(data, peer) {
+    var host = peer ? peer.host : 'unknown';
+    utils.debug(
+      'Invalid block at height %d: hash=%s peer=%s',
+      data.height,
+      utils.revHex(data.hash),
+      host
+    );
+    if (data.chain) {
+      utils.debug(
+        'Peer is sending an invalid continuation chain (%s)',
+        host);
+    } else if (data.seen) {
+      utils.debug('Peer is sending an invalid chain (%s)', host);
+    }
+  });
+
+  this.on('exists', function(data, peer) {
+    var host = peer ? peer.host : 'unknown';
+    utils.debug('Already have block %s (%s)',
+      data.height, host);
+  });
+
+  this.on('orphan', function(data, peer) {
+    var host = peer ? peer.host : 'unknown';
+    utils.debug('Handled orphan %s (%s)', utils.revHex(data.hash), host);
+  });
+
   this.loading = true;
 
   utils.debug('Chain is loading.');
@@ -725,6 +768,7 @@ Chain.prototype._saveEntry = function _saveEntry(entry, save, callback) {
 
   if (!this.tip || entry.height > this.tip.height) {
     this.tip = entry;
+    this.height = this.tip.height;
     this.emit('tip', this.tip);
   }
 
@@ -772,6 +816,8 @@ Chain.prototype.resetHeight = function resetHeight(height) {
   }
 
   this.tip = this.db.get(height);
+  assert(this.tip);
+  this.height = this.tip.height;
   this.emit('tip', this.tip);
 };
 
@@ -784,6 +830,7 @@ Chain.prototype.resetTime = function resetTime(ts) {
 
 Chain.prototype.add = function add(initial, peer, callback) {
   var self = this;
+  var host = peer ? peer.host : 'unknown';
   var code = Chain.codes.unchanged;
   var total = 0;
 
@@ -797,7 +844,23 @@ Chain.prototype.add = function add(initial, peer, callback) {
   (function next(block) {
     var hash = block.hash('hex');
     var prevHash = block.prevBlock;
-    var prevHeight, entry, existing, checkpoint, prev;
+    var prevHeight, entry, existing, checkpoint, prev, orphan;
+
+    // Special case for genesis block.
+    if (block.isGenesis())
+      return done(null, code);
+
+    // Do not revalidate known invalid blocks.
+    if (self.invalid[hash] || self.invalid[prevHash]) {
+      code = Chain.codes.invalid;
+      self.emit('invalid', {
+        height: -1,
+        hash: hash,
+        seen: true,
+        chain: self.invalid[prevHash]
+      }, peer);
+      return done(null, code);;
+    }
 
     // Find the previous block height/index.
     prevHeight = self.heightLookup[prevHash];
@@ -808,32 +871,41 @@ Chain.prototype.add = function add(initial, peer, callback) {
     // orphans.
     if (block === initial && !block.verify()) {
       code = Chain.codes.invalid;
+      self.invalid[hash] = true;
       self.emit('invalid', {
         height: prevHeight + 1,
-        hash: hash
+        hash: hash,
+        seen: false,
+        chain: false
       }, peer);
       return done(null, code);
     }
 
     // If the block is already known to be
     // an orphan, ignore it.
-    if (self.orphan.map[prevHash]) {
+    orphan = self.orphan.map[prevHash];
+    if (orphan) {
       // If the orphan chain forked, simply
       // reset the orphans and find a new peer.
-      if (self.orphan.map[prevHash].hash('hex') !== hash) {
+      if (orphan.hash('hex') !== hash) {
         self.orphan.map = {};
         self.orphan.bmap = {};
         self.orphan.count = 0;
         self.orphan.size = 0;
         self.emit('fork', {
           height: -1,
-          expected: self.orphan.map[prevHash].hash('hex'),
+          expected: orphan.hash('hex'),
           received: hash,
           checkpoint: false
         }, peer);
         code = Chain.codes.forked;
         return done(null, code);
       }
+      self.emit('orphan', {
+        height: -1,
+        hash: hash,
+        seen: true
+      }, peer);
       code = Chain.codes.knownOrphan;
       return done(null, code);
     }
@@ -846,6 +918,11 @@ Chain.prototype.add = function add(initial, peer, callback) {
       self.orphan.map[prevHash] = block;
       self.orphan.bmap[hash] = block;
       code = Chain.codes.newOrphan;
+      self.emit('orphan', {
+        height: -1,
+        hash: hash,
+        seen: false
+      }, peer);
       return done(null, code);
     }
 
@@ -870,7 +947,11 @@ Chain.prototype.add = function add(initial, peer, callback) {
     // who isn't trying to fool us.
     checkpoint = network.checkpoints[entry.height];
     if (checkpoint) {
-      self.emit('checkpoint', entry.height, entry.hash, checkpoint);
+      self.emit('checkpoint', {
+        height: entry.height,
+        hash: entry.hash,
+        checkpoint: checkpoint
+      });
       if (hash !== checkpoint) {
         // Resetting to the last checkpoint _really_ isn't
         // necessary (even bitcoind doesn't do it), but it
@@ -883,7 +964,7 @@ Chain.prototype.add = function add(initial, peer, callback) {
           expected: network.checkpoints[entry.height],
           received: entry.hash,
           checkpoint: true
-        });
+        }, peer);
         return done(null, code);
       }
     }
@@ -898,8 +979,13 @@ Chain.prototype.add = function add(initial, peer, callback) {
       // NOTE: Wrap this in a nextTick to avoid
       // a stack overflow if there are a lot of
       // existing blocks.
-      if (existing.hash === hash)
+      if (existing.hash === hash) {
+        self.emit('exists', {
+          height: entry.height,
+          hash: entry.hash
+        }, peer);
         return utils.nextTick(handleOrphans);
+      }
 
       // A valid block with an already existing
       // height came in, that spells fork. We
@@ -928,7 +1014,7 @@ Chain.prototype.add = function add(initial, peer, callback) {
         self.emit('fork', {
           height: existing.height,
           expected: existing.hash,
-          received: hash,
+          received: entry.hash,
           checkpoint: false
         }, peer);
 
@@ -954,9 +1040,12 @@ Chain.prototype.add = function add(initial, peer, callback) {
 
       if (!verified) {
         code = Chain.codes.invalid;
+        self.invalid[entry.hash] = true;
         self.emit('invalid', {
-          height: prevHeight + 1,
-          hash: hash
+          height: entry.height,
+          hash: entry.hash,
+          seen: false,
+          chain: false
         }, peer);
         return done(null, code);
       }
@@ -1057,7 +1146,7 @@ Chain.prototype.add = function add(initial, peer, callback) {
 
       item = self.pending.shift();
 
-      self.chain.add(item[0], item[1], item[2]);
+      self.add(item[0], item[1], item[2]);
     });
   }
 };
@@ -1174,7 +1263,7 @@ Chain.prototype.hashRange = function hashRange(start, end) {
 
 Chain.prototype.getLocator = function getLocator(start) {
   var hashes = [];
-  var top = this.height();
+  var top = this.height;
   var step = 1;
   var i, existing;
 
@@ -1269,12 +1358,6 @@ Chain.prototype.getSize = function getSize() {
 // Legacy
 Chain.prototype.size = Chain.prototype.getSize;
 
-Chain.prototype.height = function height() {
-  if (!this.tip)
-    return -1;
-  return this.tip.height;
-};
-
 Chain.prototype.getCurrentTarget = function getCurrentTarget() {
   if (!this.tip)
     return utils.toCompact(network.powLimit);
diff --git a/lib/bcoin/coin.js b/lib/bcoin/coin.js
index 0d4cb0e0..1daddd0e 100644
--- a/lib/bcoin/coin.js
+++ b/lib/bcoin/coin.js
@@ -85,7 +85,7 @@ Coin.prototype.getConfirmations = function getConfirmations(height) {
     if (!this.chain)
       return 0;
 
-    top = this.chain.height();
+    top = this.chain.height;
   } else {
     top = height;
   }
diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index 672adb24..9a5656df 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -251,7 +251,7 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback) {
       return callback(new Error('TX is spending coins that it does not have.'));
     }
 
-    height = self.pool.chain.height() + 1;
+    height = self.pool.chain.height + 1;
     ts = utils.now();
     if (!tx.isFinal(height, ts)) {
       return callback(new Error('TX is not final.'));
diff --git a/lib/bcoin/peer.js b/lib/bcoin/peer.js
index 5f9037fc..3765f45f 100644
--- a/lib/bcoin/peer.js
+++ b/lib/bcoin/peer.js
@@ -148,7 +148,7 @@ Peer.prototype._init = function init() {
   this.once('version', function() {
     utils.debug(
       'Sent version (%s): height=%s',
-      self.host, this.pool.chain.height());
+      self.host, this.pool.chain.height);
   });
 
   this._ping.timer = setInterval(function() {
@@ -176,7 +176,7 @@ Peer.prototype._init = function init() {
 
   // Send hello
   this._write(this.framer.version({
-    height: this.pool.chain.height(),
+    height: this.pool.chain.height,
     relay: this.options.relay
   }));
 };
diff --git a/lib/bcoin/pool.js b/lib/bcoin/pool.js
index d12dfa4c..5a586758 100644
--- a/lib/bcoin/pool.js
+++ b/lib/bcoin/pool.js
@@ -84,9 +84,6 @@ function Pool(options) {
     interval: options.loadInterval || 5000
   };
 
-  this._pendingBlocks = [];
-  this._locked = false;
-
   this.requestTimeout = options.requestTimeout || 600000;
 
   this.chain = new bcoin.chain({
@@ -192,16 +189,7 @@ Pool.prototype._init = function _init() {
   });
 
   this.chain.on('fork', function(data, peer) {
-    utils.debug(
-      'Fork at height %d: expected=%s received=%s checkpoint=%s peer=%s',
-      data.height,
-      utils.revHex(data.expected),
-      utils.revHex(data.received),
-      data.checkpoint,
-      peer ? peer.host : ''
-    );
-
-    self.emit('fork', data.expected, data.received);
+    self.emit('fork', data, peer);
 
     if (!peer)
       return;
@@ -217,21 +205,47 @@ Pool.prototype._init = function _init() {
   });
 
   this.chain.on('invalid', function(data, peer) {
-    utils.debug(
-      'Invalid block at height %d: hash=%s peer=%s',
-      data.height,
-      utils.revHex(data.hash),
-      peer ? peer.host : ''
-    );
-
-    self.block.invalid[data.hash] = true;
-
     if (!peer)
       return;
 
     self.setMisbehavior(peer, 100);
   });
 
+  this.chain.on('exists', function(data, peer) {
+    if (!peer)
+      return;
+
+    self.setMisbehavior(peer, 1);
+  });
+
+  this.chain.on('orphan', function(data, peer) {
+    var host = peer ? peer.host : 'unknown';
+
+    if (!peer)
+      return;
+
+    // Resolve orphan chain
+    if (!self.options.headers) {
+      // Make sure the peer doesn't send us
+      // more than 200 orphans every 3 minutes.
+      if (self.isOrphaning(peer)) {
+        utils.debug('Peer is orphaning (%s)', host);
+        self.setMisbehavior(peer, 100);
+        return;
+      }
+
+      // Resolve orphan chain.
+      self.peers.load.loadBlocks(
+        self.chain.getLocator(),
+        self.chain.getOrphanRoot(data.hash)
+      );
+    } else {
+      // Increase banscore by 10 if we're using getheaders.
+      if (!self.options.multiplePeers)
+        self.setMisbehavior(peer, 10);
+    }
+  });
+
   this.options.wallets.forEach(function(w) {
     self.addWallet(w);
   });
@@ -240,7 +254,7 @@ Pool.prototype._init = function _init() {
   if (this.chain.isFull()) {
     this.synced = true;
     this.emit('full');
-    utils.debug('Chain is fully synced (height=%d).', this.chain.height());
+    utils.debug('Chain is fully synced (height=%d).', this.chain.height);
   }
 
   this.startServer();
@@ -299,7 +313,7 @@ Pool.prototype._startTimer = function _startTimer() {
       self._stopInterval();
       self.synced = true;
       self.emit('full');
-      utils.debug('Chain is fully synced (height=%d).', self.chain.height());
+      utils.debug('Chain is fully synced (height=%d).', self.chain.height);
       return;
     }
 
@@ -608,176 +622,53 @@ Pool.prototype._prehandleBlock = function _prehandleBlock(block, peer, callback)
 
 Pool.prototype._handleBlock = function _handleBlock(block, peer, callback) {
   var self = this;
+  var requested;
 
-  if (this._locked) {
-    this._pendingBlocks.push([block, peer, callback]);
-    return;
-  }
+  callback = utils.asyncify(callback);
 
-  this._locked = true;
+  // Fulfill our request.
+  requested = self._response(block);
 
-  function done(err, result) {
-    var item;
-
-    utils.nextTick(function() {
-      callback(err, result);
-
-      self._locked = false;
-
-      if (self._pendingBlocks.length === 0)
-        return;
-
-      item = self._pendingBlocks.shift();
-
-      self._handleBlock(item[0], item[1], item[2]);
-    });
+  // Someone is sending us blocks without
+  // us requesting them.
+  if (!requested) {
+    utils.debug(
+      'Recieved unrequested block: %s (%s)',
+      block.rhash, peer.host);
   }
 
   this._prehandleBlock(block, peer, function(err) {
-    var requested;
-
-    if (err)
-      return done(err);
-
-    // Fulfill our request.
-    requested = self._response(block);
-
-    // Ensure the block was not invalid last time.
-    // Someone might be sending us bad blocks to DoS us.
-    if (self.block.invalid[block.hash('hex')]) {
-      utils.debug('Peer is sending an invalid chain (%s)', peer.host);
-      self.setMisbehavior(peer, 100);
-      return done(null, false);
-    }
-
-    // Ensure this is not a continuation
-    // of an invalid chain.
-    if (self.block.invalid[block.prevBlock]) {
-      utils.debug(
-        'Peer is sending an invalid continuation chain (%s)',
-        peer.host);
-      self.setMisbehavior(peer, 100);
-      return done(null, false);
-    }
-
-    // Ignore if we already have.
-    if (self.chain.has(block)) {
-      utils.debug('Already have block %s (%s)',
-        self.chain.getHeight(block), peer.host);
-      self.setMisbehavior(peer, 1);
-      return done(null, false);
-    }
-
-    // Make sure the block is valid.
-    if (!block.verify()) {
-      utils.debug(
-        'Block verification failed for %s (%s)',
-        block.rhash, peer.host);
-      self.block.invalid[block.hash('hex')] = true;
-      self.setMisbehavior(peer, 100);
-      return done(null, false);
-    }
-
-    // Someone is sending us blocks without
-    // us requesting them.
-    if (!requested) {
-      utils.debug(
-        'Recieved unrequested block: %s (%s)',
-        block.rhash, peer.host);
-    }
-
-    // Resolve orphan chain
-    if (!self.options.headers) {
-      if (!self.chain.hasBlock(block.prevBlock)) {
-        // Special case for genesis block.
-        if (block.isGenesis())
-          return done(null, false);
-
-        // Make sure the peer doesn't send us
-        // more than 200 orphans every 3 minutes.
-        if (self.isOrphaning(peer)) {
-          utils.debug('Peer is orphaning (%s)', peer.host);
-          self.setMisbehavior(peer, 100);
-          return done(null, false);
-        }
-
-        // NOTE: If we were to emit new orphans here, we
-        // would not need to store full blocks as orphans.
-        // However, the listener would not be able to see
-        // the height until later.
-        self._addIndex(block, peer, function(err, added) {
-          if (err)
-            return done(err);
-
-          // Resolve orphan chain.
-          self.peers.load.loadBlocks(
-            self.chain.getLocator(),
-            self.chain.getOrphanRoot(block)
-          );
-
-          utils.debug('Handled orphan %s (%s)', block.rhash, peer.host);
-
-          return done(null, false);
-        });
-
-        return;
-      }
-    } else {
-      if (!self.chain.hasBlock(block.prevBlock)) {
-        // Special case for genesis block.
-        if (block.isGenesis())
-          return done(null, false);
-
-        // Increase banscore by 10 if we're using getheaders.
-        if (!self.options.multiplePeers) {
-          if (self.setMisbehavior(peer, 10))
-            return done(null, false);
-        }
-      }
-    }
-
-    // Add to index and emit/save
-    self._addIndex(block, peer, function(err, added) {
-      if (err)
-        return done(err);
-
-      if (added)
-        return done(null, true);
-
-      return done(null, false);
-    });
-  });
-};
-
-Pool.prototype._addIndex = function _addIndex(block, peer, callback) {
-  var self = this;
-  this.chain.add(block, peer, function(err, added) {
     if (err)
       return callback(err);
 
-    if (added === 0)
-      return callback(null, false);
+    self.chain.add(block, peer, function(err, added) {
+      if (err)
+        return callback(err);
 
-    self.emit('chain-progress', self.chain.fillPercent(), peer);
+      if (added === 0)
+        return callback(null, false);
 
-    self.block.total += added;
+      self.emit('chain-progress', self.chain.fillPercent(), peer);
 
-    if (self.chain.height() % 20 === 0) {
-      utils.debug(
-        'Got: %s from %s chain len %d blocks %d orp %d act %d queue %d target %s peers %d pending %d',
-        block.rhash,
-        new Date(block.ts * 1000).toString(),
-        self.chain.height(),
-        self.block.total,
-        self.chain.orphan.count,
-        self.request.active,
-        peer._blockQueue.length,
-        self.chain.currentTarget(),
-        self.peers.all.length,
-        self._pendingBlocks.length);
-    }
+      self.block.total += added;
 
-    return callback(null, true);
+      if (self.chain.height % 20 === 0) {
+        utils.debug(
+          'Got: %s from %s chain len %d blocks %d orp %d act %d queue %d target %s peers %d pending %d',
+          block.rhash,
+          new Date(block.ts * 1000).toString(),
+          self.chain.height,
+          self.block.total,
+          self.chain.orphan.count,
+          self.request.activeBlocks,
+          peer._blockQueue.length,
+          self.chain.currentTarget(),
+          self.peers.all.length,
+          self.chain.pending.length);
+      }
+
+      return callback(null, true);
+    });
   });
 };
 
@@ -887,9 +778,13 @@ Pool.prototype._createPeer = function _createPeer(options) {
 
 Pool.prototype._handleTX = function _handleTX(tx, peer, callback) {
   var self = this;
+  var requested, added;
 
   callback = utils.asyncify(callback);
 
+  requested = self._response(tx);
+  added = self._addTX(tx, 1);
+
   function addMempool(tx, peer, callback) {
     if (!self.mempool)
       return callback();
@@ -903,14 +798,9 @@ Pool.prototype._handleTX = function _handleTX(tx, peer, callback) {
       return callback(err);
 
     addMempool(tx, peer, function(err) {
-      var requested, added;
-
       if (err && self.synced)
         utils.debug('Mempool error: %s', err.message);
 
-      requested = self._response(tx);
-      added = self._addTX(tx, 1);
-
       if (added || tx.block)
         self.emit('tx', tx, peer);
 
@@ -1403,13 +1293,13 @@ Pool.prototype.searchWallet = function(w, h) {
   if (height > 0) {
     // Back one week
     if (!height || height === -1)
-      height = this.chain.height() - (7 * 24 * 6);
+      height = this.chain.height - (7 * 24 * 6);
 
     utils.nextTick(function() {
       utils.debug('Wallet height: %s', height);
       utils.debug(
         'Reverted chain to height=%d',
-        self.chain.height()
+        self.chain.height
       );
     });
 
@@ -1425,7 +1315,7 @@ Pool.prototype.searchWallet = function(w, h) {
     utils.debug('Wallet time: %s', new Date(ts * 1000));
     utils.debug(
       'Reverted chain to height=%d (%s)',
-      self.chain.height(),
+      self.chain.height,
       new Date(self.chain.tip.ts * 1000)
     );
   });
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index 1dfeba5d..74c6a30a 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -1406,7 +1406,7 @@ TX.prototype.avoidFeeSnipping = function avoidFeeSnipping(height) {
     if (!this.chain)
       return;
 
-    height = this.chain.height();
+    height = this.chain.height;
   }
 
   if (height === -1)
@@ -1704,7 +1704,7 @@ TX.prototype.getConfirmations = function getConfirmations(height) {
     if (!this.chain)
       return 0;
 
-    top = this.chain.height();
+    top = this.chain.height;
   } else {
     top = height;
   }