Adding block_pipeline::epoch_restrictions_filter which only allows ep…

…och blocks to pass if they don't modify the state of the account other than its epoch.

nano/core_test/CMakeLists.txt

@@ -19,6 +19,7 @@ add_executable(
   stateless_signer_filter.cpp
   election.cpp
   election_scheduler.cpp
+  epoch_restrictions_filter.cpp
   epochs.cpp
   existing_block_filter.cpp
   metastable_filter.cpp

nano/core_test/epoch_restrictions_filter.cpp

@@ -0,0 +1,111 @@
+#include <nano/node/block_pipeline/context.hpp>
+#include <nano/node/block_pipeline/epoch_restrictions_filter.hpp>
+#include <nano/secure/common.hpp>
+
+#include <gtest/gtest.h>
+
+namespace
+{
+class context
+{
+public:
+	context ()
+	{
+		filter.pass = [this] (nano::block_pipeline::context & context) {
+			pass.push_back (context);
+		};
+		filter.reject_balance = [this] (nano::block_pipeline::context & context) {
+			reject_balance.push_back (context);
+		};
+		filter.reject_representative = [this] (nano::block_pipeline::context & context) {
+			reject_representative.push_back (context);
+		};
+	}
+	nano::block_pipeline::epoch_restrictions_filter filter;
+	std::vector<nano::block_pipeline::context> pass;
+	std::vector<nano::block_pipeline::context> reject_balance;
+	std::vector<nano::block_pipeline::context> reject_representative;
+};
+nano::block_pipeline::context epoch_pass_blocks ()
+{
+	nano::block_builder builder;
+	nano::block_pipeline::context result;
+	result.block = builder.state ()
+				   .account (nano::dev::genesis_key.pub)
+				   .previous (nano::dev::genesis->hash ())
+				   .representative (nano::dev::genesis_key.pub)
+				   .balance (nano::dev::constants.genesis_amount) // Unchanged balance
+				   .link (nano::dev::constants.epochs.link (nano::epoch::epoch_1))
+				   .sign (nano::dev::genesis_key.prv, nano::dev::genesis_key.pub)
+				   .work (0)
+				   .build_shared ();
+	result.previous = nano::dev::genesis;
+	result.state = nano::account_info{};
+	result.state->balance = nano::dev::constants.genesis_amount;
+	result.state->representative = nano::dev::genesis_key.pub;
+	return result;
+}
+nano::block_pipeline::context epoch_reject_balance_blocks ()
+{
+	nano::block_builder builder;
+	nano::block_pipeline::context result;
+	result.block = builder.state ()
+				   .account (nano::dev::genesis_key.pub)
+				   .previous (nano::dev::genesis->hash ())
+				   .representative (nano::dev::genesis_key.pub) // Unchacked representative
+				   .balance (nano::dev::constants.genesis_amount - 1)
+				   .link (nano::dev::constants.epochs.link (nano::epoch::epoch_1))
+				   .sign (nano::dev::genesis_key.prv, nano::dev::genesis_key.pub)
+				   .work (0)
+				   .build_shared ();
+	result.previous = nano::dev::genesis;
+	result.state = nano::account_info{};
+	result.state->balance = nano::dev::constants.genesis_amount; // Changed balance
+	result.state->representative = nano::dev::genesis_key.pub;
+	return result;
+}
+nano::block_pipeline::context epoch_reject_representative_blocks ()
+{
+	nano::block_builder builder;
+	nano::block_pipeline::context result;
+	result.block = builder.state ()
+				   .account (nano::dev::genesis_key.pub)
+				   .previous (nano::dev::genesis->hash ())
+				   .representative (nano::dev::genesis_key.pub)
+				   .balance (nano::dev::constants.genesis_amount) // Unchanged balance
+				   .link (nano::dev::constants.epochs.link (nano::epoch::epoch_1))
+				   .sign (nano::dev::genesis_key.prv, nano::dev::genesis_key.pub)
+				   .work (0)
+				   .build_shared ();
+	result.previous = nano::dev::genesis;
+	result.state = nano::account_info{};
+	result.state->balance = nano::dev::constants.genesis_amount;
+	nano::keypair dummy;
+	result.state->representative = dummy.pub; // Changed representative
+	return result;
+}
+}
+
+TEST (epoch_restrictions_filter, epoch_pass)
+{
+	context context;
+	auto blocks = epoch_pass_blocks ();
+	context.filter.sink (blocks);
+	ASSERT_EQ (1, context.pass.size ());
+}
+
+TEST (epoch_restrictions_filter, epoch_reject_balance)
+{
+	context context;
+	auto blocks = epoch_reject_balance_blocks ();
+	context.filter.sink (blocks);
+	ASSERT_EQ (1, context.reject_balance.size ());
+}
+
+TEST (epoch_restrictions_filter, epoch_reject_representative)
+{
+	context context;
+	auto blocks = epoch_reject_representative_blocks ();
+	context.filter.sink (blocks);
+	ASSERT_EQ (1, context.reject_representative.size ());
+}

nano/node/CMakeLists.txt

@@ -22,6 +22,8 @@ add_library(
   block_pipeline/block_position_filter.hpp
   block_pipeline/context.cpp
   block_pipeline/context.hpp
+  block_pipeline/epoch_restrictions_filter.cpp
+  block_pipeline/epoch_restrictions_filter.hpp
   block_pipeline/existing_block_filter.cpp
   block_pipeline/existing_block_filter.hpp
   block_pipeline/link_filter.cpp

nano/node/block_pipeline/account_state_decorator.cpp

@@ -12,6 +12,6 @@ nano::block_pipeline::account_state_decorator::account_state_decorator (nano::le
 
 void nano::block_pipeline::account_state_decorator::sink (context & context) const
 {
-	context.info = ledger.account_info (ledger.store.tx_begin_read (), context.account ());
+	context.state = ledger.account_info (ledger.store.tx_begin_read (), context.account ());
 	output (context);
 }

nano/node/block_pipeline/epoch_restrictions_filter.cpp

@@ -0,0 +1,18 @@
+#include <nano/node/block_pipeline/context.hpp>
+#include <nano/node/block_pipeline/epoch_restrictions_filter.hpp>
+
+void nano::block_pipeline::epoch_restrictions_filter::sink (context & context)
+{
+	debug_assert (context.state.has_value ());
+	if (context.state->balance != context.block->balance ())
+	{
+		reject_balance (context);
+		return;
+	}
+	if (context.state->representative != context.block->representative ())
+	{
+		reject_representative (context);
+		return;
+	}
+	pass (context);
+}

nano/node/block_pipeline/epoch_restrictions_filter.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <functional>
+
+namespace nano
+{
+namespace block_pipeline
+{
+	class context;
+	/**
+	  This filter checks the restrictions on epoch blocks.
+	  Epoch blocks cannot change the state of an account other than changing the account's epoch
+	 */
+	class epoch_restrictions_filter
+	{
+	public:
+		void sink (context & context);
+		std::function<void (context & context)> pass;
+		std::function<void (context & context)> reject_balance;
+		std::function<void (context & context)> reject_representative;
+	};
+}
+}

nano/node/blockprocessor.hpp

@@ -4,6 +4,7 @@
 #include <nano/node/block_pipeline/account_state_decorator.hpp>
 #include <nano/node/block_pipeline/block_position_filter.hpp>
 #include <nano/node/block_pipeline/context.hpp>
+#include <nano/node/block_pipeline/epoch_restrictions_filter.hpp>
 #include <nano/node/block_pipeline/existing_block_filter.hpp>
 #include <nano/node/block_pipeline/gap_previous_filter.hpp>
 #include <nano/node/block_pipeline/link_filter.hpp>
@@ -111,6 +112,7 @@ class block_processor final
 	nano::block_pipeline::account_state_decorator account_state;
 	nano::block_pipeline::metastable_filter metastable;
 	nano::block_pipeline::link_filter link;
+	nano::block_pipeline::epoch_restrictions_filter epoch_restrictions;
 	nano::block_pipeline::signer_decorator signer_decorator;
 	nano::state_block_signature_verification state_block_signature_verification;