Verify block slot window

helpers/constants.js

@@ -51,6 +51,7 @@ module.exports = {
 	activeDelegates: 101,
 	addressLength: 208,
 	blockHeaderLength: 248,
+	blockSlotWindow: 5, // window in which a slot could be accepted	
 	blockTime: 27000,
 	blockReceiptTimeOut: 27*2, // 2 blocks
 	confirmationLength: 77,

modules/blocks/process.js

@@ -472,6 +472,10 @@ __private.receiveForkOne = function (block, lastBlock, cb) {
 					return setImmediate(seriesCb);
 				}
 			},
+			// Verify block slot window
+			function (seriesCb) {
+				modules.delegates.validateBlockSlot(tmp_block, seriesCb);
+			},
 			// Delete last 2 blocks
 			modules.blocks.chain.deleteLastBlock,
 			modules.blocks.chain.deleteLastBlock

modules/blocks/verify.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var async = require('async');
+var _ = require('lodash');
 var BlockReward = require('../../logic/blockReward.js');
 var constants = require('../../helpers/constants.js');
 var crypto = require('crypto');
@@ -11,6 +12,7 @@ var exceptions = require('../../helpers/exceptions.js');
 var modules, library, self, __private = {};
 
 __private.blockReward = new BlockReward();
+__private.lastNBlockIds = [];
 
 function Verify (logger, block, transaction, db) {
 	library = {
@@ -326,6 +328,68 @@ __private.verifyBlockSlot = function (block, lastBlock, result) {
 	return result;
 };
 
+/**
+ * Verify block is not one of the last {constants.blockSlotWindow} saved blocks
+ *
+ * @private
+ * @method verifyAgainstLastNBlockIds
+ * @param  {Object}  block Target block
+ * @param  {Object}  result Verification results
+ * @return {Object}  result Verification results
+ * @return {boolean} result.verified Indicator that verification passed
+ * @return {Array}   result.errors Array of validation errors
+ */
+__private.verifyAgainstLastNBlockIds = function (block, result) {
+  if (__private.lastNBlockIds.indexOf(block.id) !== -1) {
+    result.errors.push('Block already exists in chain');
+  };
+
+  return result;
+};
+
+/**
+ * Verify block slot window according to application time
+ *
+ * @private
+ * @method verifyBlockSlotWindow
+ * @param  {Object}  block Target block
+ * @return {Object}  result Verification results
+ * @return {boolean} result.verified Indicator that verification passed
+ * @return {Array}   result.errors Array of validation errors
+ */
+__private.verifyBlockSlotWindow = function (block, result) {
+  var currentApplicationSlot = slots.getSlotNumber();
+  var blockSlot = slots.getSlotNumber(block.timestamp);
+
+  // Reject block if it's slot is older than constants.blockSlotWindow
+  if (currentApplicationSlot - blockSlot > constants.blockSlotWindow) {
+    result.errors.push('Block slot is too old');
+  }
+
+  // Reject block if it's slot is in the future
+  if (currentApplicationSlot < blockSlot) {
+    result.errors.push('Block slot is in the future');
+  }
+
+  return result;
+};
+
+Verify.prototype.onBlockchainReady = function () {
+  return library.db.query(sql.loadLastNBlockIds, {limit: constants.blockSlotWindow}).then(function (blockIds) {
+    __private.lastNBlockIds = _.map(blockIds, 'id');
+  }).catch(function (err) {
+    library.logger.error('Unable to load last ' + constants.blockSlotWindow + ' block ids');
+    library.logger.error(err);
+  });
+};
+
+Verify.prototype.onNewBlock = function (block) {
+  __private.lastNBlockIds.push(block.id);
+  if (__private.lastNBlockIds.length > constants.blockSlotWindow) {
+    __private.lastNBlockIds.shift();
+  }
+};
+
 /**
  * Verify block before fork detection and return all possible errors related to block
  *
@@ -345,6 +409,8 @@ Verify.prototype.verifyReceipt = function (block) {
 
 	result = __private.verifySignature(block, result);
 	result = __private.verifyPreviousBlock(block, result);
+	result = __private.verifyAgainstLastNBlockIds(block, result);
+	result = __private.verifyBlockSlotWindow(block, result);
 	result = __private.verifyVersion(block, result);
 	result = __private.verifyReward(block, result);
 	result = __private.verifyId(block, result);

sql/blocks.js

@@ -102,6 +102,8 @@ var BlocksSql = {
   loadBlocksOffset: 'SELECT * FROM full_blocks_list WHERE "b_height" >= ${offset} AND "b_height" < ${limit} ORDER BY "b_height", "t_rowId"',
 
   loadLastBlock: 'SELECT * FROM full_blocks_list WHERE "b_height" = (SELECT MAX("height") FROM blocks) ORDER BY "b_height", "t_rowId"',
+
+  loadLastNBlockIds: 'SELECT "id" FROM blocks ORDER BY "height" DESC LIMIT ${limit}',
 
   getBlockId: 'SELECT "id" FROM blocks WHERE "id" = ${id}',