chain/pool: disable checkpoints on checkpoint failure. see #121.

etc/sample.conf

@@ -53,7 +53,6 @@ replace-by-fee: false
 #
 
 selfish: false
-headers: true
 compact: true
 bip151: true
 listen: true

lib/blockchain/chain.js

@@ -1685,17 +1685,20 @@ Chain.prototype.maybeSync = function maybeSync() {
   if (this.synced)
     return;
 
-  if (!this.hasChainwork())
-    return;
-
   if (this.checkpoints) {
-    this.logger.info('Minimum chainwork reached. Disabling checkpoints.');
+    if (this.tip.height < this.network.lastCheckpoint)
+      return;
+
+    this.logger.info('Last checkpoint reached. Disabling checkpoints.');
     this.checkpoints = false;
   }
 
   if (this.tip.ts < util.now() - this.network.block.maxTipAge)
     return;
 
+  if (!this.hasChainwork())
+    return;
+
   this.synced = true;
   this.emit('full');
 };
@@ -2302,7 +2305,7 @@ function ChainOptions(options) {
   this.coinCache = 0;
   this.entryCache = (2016 + 1) * 2 + 100;
   this.orphanLimit = 20 << 20;
-  this.checkpoints = false;
+  this.checkpoints = true;
 
   if (options)
     this.fromOptions(options);

lib/net/pool.js

@@ -47,8 +47,6 @@ var packetTypes = packets.types;
  * @param {Boolean?} options.spv - Do an SPV sync.
  * @param {Boolean?} options.noRelay - Whether to ask
  * for relayed transactions.
- * @param {Boolean?} options.headers - Whether
- * to use `getheaders` for sync.
  * @param {Number?} [options.feeRate] - Fee filter rate.
  * @param {Number?} [options.invTimeout=60000] - Timeout for broadcasted
  * objects.
@@ -116,6 +114,7 @@ function Pool(options) {
   this.headerChain = new List();
   this.headerNext = null;
   this.headerTip = null;
+  this.headerFails = 0;
 
   this.peers = new PeerList();
   this.authdb = new BIP150.AuthDB(this.options);
@@ -231,7 +230,7 @@ Pool.prototype._open = co(function* _open() {
 Pool.prototype.resetChain = function resetChain() {
   var tip = this.chain.tip;
 
-  if (!this.options.headers)
+  if (!this.options.checkpoints)
     return;
 
   this.headersFirst = false;
@@ -239,14 +238,14 @@ Pool.prototype.resetChain = function resetChain() {
   this.headerChain.reset();
   this.headerNext = null;
 
-  if (!this.chain.hasChainwork()) {
+  if (tip.height < this.network.lastCheckpoint) {
     this.headersFirst = true;
     this.headerTip = this.getNextTip(tip.height);
     this.headerChain.push(new HeaderEntry(tip.hash, tip.height));
     this.logger.info(
-      'Initialized header chain to height %d (watermark=%d).',
+      'Initialized header chain to height %d (checkpoint=%s).',
       tip.height,
-      this.headerTip.height);
+      this.headerTip.hash);
   }
 };
 
@@ -680,7 +679,7 @@ Pool.prototype.resolveHeaders = function resolveHeaders(peer) {
 };
 
 /**
- * Find the next highest watermark block.
+ * Find the next checkpoint.
  * @private
  * @param {Number} height
  * @returns {Object}
@@ -689,19 +688,13 @@ Pool.prototype.resolveHeaders = function resolveHeaders(peer) {
 Pool.prototype.getNextTip = function getNextTip(height) {
   var i, next;
 
-  if (this.options.checkpoints) {
-    for (i = 0; i < this.network.checkpoints.length; i++) {
-      next = this.network.checkpoints[i];
-      if (next.height > height)
-        return new HeaderEntry(next.hash, next.height);
-    }
-    throw new Error('Could not find next tip.');
+  for (i = 0; i < this.network.checkpoints.length; i++) {
+    next = this.network.checkpoints[i];
+    if (next.height > height)
+      return new HeaderEntry(next.hash, next.height);
   }
 
-  if (this.chain.hasChainwork())
-    throw new Error('Could not find next tip.');
-
-  return new HeaderEntry(null, height + 20000);
+  throw new Error('Next checkpoint not found.');
 };
 
 /**
@@ -1755,7 +1748,7 @@ Pool.prototype.handleHeaders = co(function* handleHeaders(peer, packet) {
 
 Pool.prototype._handleHeaders = co(function* handleHeaders(peer, packet) {
   var headers = packet.items;
-  var isWatermark = false;
+  var checkpoint = false;
   var i, header, hash, height, last, node;
 
   if (!this.headersFirst)
@@ -1783,14 +1776,6 @@ Pool.prototype._handleHeaders = co(function* handleHeaders(peer, packet) {
     hash = header.hash('hex');
     height = last.height + 1;
 
-    if (header.prevBlock !== last.hash) {
-      this.logger.warning(
-        'Peer sent a bad header chain (%s).',
-        peer.hostname());
-      peer.destroy();
-      return;
-    }
-
     if (!header.verify()) {
       this.logger.warning(
         'Peer sent an invalid header (%s).',
@@ -1800,20 +1785,45 @@ Pool.prototype._handleHeaders = co(function* handleHeaders(peer, packet) {
       return;
     }
 
+    if (header.prevBlock !== last.hash) {
+      this.logger.warning(
+        'Peer sent a bad header chain (%s).',
+        peer.hostname());
+
+      if (++this.headerFails < 4) {
+        peer.destroy();
+        return;
+      }
+
+      this.logger.warning(
+        'Switching to getblocks (%s).',
+        peer.hostname());
+
+      yield this.switchSync(peer);
+      return;
+    }
+
     node = new HeaderEntry(hash, height);
 
     if (node.height === this.headerTip.height) {
-      if (this.options.checkpoints) {
-        if (node.hash !== this.headerTip.hash) {
-          this.logger.warning(
-            'Peer sent an invalid checkpoint (%s).',
-            peer.hostname());
-          peer.increaseBan(100);
+      if (node.hash !== this.headerTip.hash) {
+        this.logger.warning(
+          'Peer sent an invalid checkpoint (%s).',
+          peer.hostname());
+
+        if (++this.headerFails < 4) {
           peer.destroy();
           return;
         }
+
+        this.logger.warning(
+          'Switching to getblocks (%s).',
+          peer.hostname());
+
+        yield this.switchSync(peer);
+        return;
       }
-      isWatermark = true;
+      checkpoint = true;
     }
 
     if (!this.headerNext)
@@ -1828,7 +1838,7 @@ Pool.prototype._handleHeaders = co(function* handleHeaders(peer, packet) {
     peer.hostname());
 
   // Request the blocks we just added.
-  if (isWatermark) {
+  if (checkpoint) {
     this.headerChain.shift();
     this.resolveHeaders(peer);
     return;
@@ -1971,10 +1981,10 @@ Pool.prototype.resolveChain = co(function* resolveChain(peer, hash) {
     return;
   }
 
-  if (!this.chain.hasChainwork()) {
+  if (node.height < this.network.lastCheckpoint) {
     if (node.height === this.headerTip.height) {
       this.logger.info(
-        'Hit high watermark %s (%d).',
+        'Received checkpoint %s (%d).',
         util.revHex(node.hash), node.height);
 
       this.headerTip = this.getNextTip(node.height);
@@ -1991,9 +2001,24 @@ Pool.prototype.resolveChain = co(function* resolveChain(peer, hash) {
   }
 
   this.logger.info(
-    'Chain hit target chainwork of %s. Switching to getblocks.',
-    this.chain.tip.chainwork.toString('hex', 64));
+    'Switching to getblocks (%s).',
+    peer.hostname());
 
+  yield this.switchSync(peer, hash);
+});
+
+/**
+ * Switch to getblocks.
+ * @private
+ * @param {Peer} peer
+ * @param {Hash} hash
+ * @returns {Promise}
+ */
+
+Pool.prototype.switchSync = co(function* switchSync(peer, hash) {
+  assert(this.headersFirst);
+
+  this.chain.checkpoints = false;
   this.headersFirst = false;
   this.headerTip = null;
   this.headerChain.reset();
@@ -3165,10 +3190,9 @@ function PoolOptions(options) {
   this.address.port = this.network.port;
 
   this.witness = true;
-  this.checkpoints = false;
+  this.checkpoints = true;
   this.spv = false;
   this.listen = false;
-  this.headers = false;
   this.compact = false;
   this.noRelay = false;
   this.host = '0.0.0.0';
@@ -3259,13 +3283,6 @@ PoolOptions.prototype.fromOptions = function fromOptions(options) {
     this.listen = options.listen;
   }
 
-  if (options.headers != null) {
-    assert(typeof options.headers === 'boolean');
-    this.headers = options.headers;
-  } else {
-    this.headers = this.spv === true;
-  }
-
   if (options.compact != null) {
     assert(typeof options.compact === 'boolean');
     this.compact = options.compact;
@@ -3419,6 +3436,7 @@ PoolOptions.prototype.fromOptions = function fromOptions(options) {
     this.requiredServices |= common.services.BLOOM;
     this.services &= ~common.services.NETWORK;
     this.noRelay = true;
+    this.checkpoints = true;
   }
 
   if (this.selfish)

lib/node/fullnode.js

@@ -102,7 +102,6 @@ function FullNode(options) {
     chain: this.chain,
     mempool: this.mempool,
     selfish: this.options.selfish,
-    headers: this.options.headers,
     compact: this.options.compact,
     bip151: this.options.bip151,
     bip150: this.options.bip150,

lib/node/spvnode.js

@@ -71,7 +71,6 @@ function SPVNode(options) {
     knownPeers: this.options.knownPeers,
     identityKey: this.options.identityKey,
     maxOutbound: this.options.maxOutbound,
-    headers: this.options.headers,
     selfish: true,
     listen: false
   });

lib/protocol/networks.js

@@ -181,7 +181,7 @@ main.pow = {
    */
 
   chainwork: new BN(
-    '0000000000000000000000000000000000000000002fa4573e5f9cf6ca3e5e75',
+    '0000000000000000000000000000000000000000003a315fa3a5ef47f4384cf2',
     'hex'
   ),
 
@@ -543,7 +543,7 @@ testnet.pow = {
   ),
   bits: 486604799,
   chainwork: new BN(
-    '00000000000000000000000000000000000000000000001a461538dc48da1a06',
+    '00000000000000000000000000000000000000000000001e345893fa639796e9',
     'hex'
   ),
   targetTimespan: 14 * 24 * 60 * 60,