2015-04-29 16:16:05 +00:00
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/*
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This file is part of cpp-ethereum.
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cpp-ethereum is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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cpp-ethereum is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file KnownState.h
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* @author Christian <c@ethdev.com>
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* @date 2015
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* Contains knowledge about the state of the virtual machine at a specific instruction.
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*/
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#pragma once
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#include <vector>
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#include <map>
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#include <set>
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#include <tuple>
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2015-05-04 08:15:41 +00:00
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#include <memory>
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#include <ostream>
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2015-08-06 13:27:50 +00:00
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#pragma warning(push)
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#pragma GCC diagnostic push
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2015-08-06 13:56:00 +00:00
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#pragma clang diagnostic ignored "-Wredeclared-class-member"
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2015-05-12 19:27:04 +00:00
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#include <boost/bimap.hpp>
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#pragma warning(pop)
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#pragma GCC diagnostic pop
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2015-04-29 16:16:05 +00:00
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#include <libdevcore/CommonIO.h>
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#include <libdevcore/Exceptions.h>
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#include <libevmasm/ExpressionClasses.h>
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#include <libevmasm/SemanticInformation.h>
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namespace dev
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{
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namespace eth
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{
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class AssemblyItem;
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using AssemblyItems = std::vector<AssemblyItem>;
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/**
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* Class to infer and store knowledge about the state of the virtual machine at a specific
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* instruction.
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*
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* The general workings are that for each assembly item that is fed, an equivalence class is
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* derived from the operation and the equivalence class of its arguments. DUPi, SWAPi and some
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* arithmetic instructions are used to infer equivalences while these classes are determined.
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*/
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class KnownState
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{
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public:
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using Id = ExpressionClasses::Id;
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struct StoreOperation
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{
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enum Target { Invalid, Memory, Storage };
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StoreOperation(): target(Invalid), sequenceNumber(-1) {}
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StoreOperation(
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Target _target,
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Id _slot,
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unsigned _sequenceNumber,
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Id _expression
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): target(_target), slot(_slot), sequenceNumber(_sequenceNumber), expression(_expression) {}
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bool isValid() const { return target != Invalid; }
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Target target;
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Id slot;
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unsigned sequenceNumber;
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Id expression;
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};
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explicit KnownState(
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std::shared_ptr<ExpressionClasses> _expressionClasses = std::make_shared<ExpressionClasses>()
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): m_expressionClasses(_expressionClasses)
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{
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}
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/// Streams debugging information to @a _out.
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std::ostream& stream(std::ostream& _out) const;
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/// Feeds the item into the system for analysis.
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/// @returns a possible store operation
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StoreOperation feedItem(AssemblyItem const& _item, bool _copyItem = false);
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/// Resets any knowledge about storage.
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void resetStorage() { m_storageContent.clear(); }
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/// Resets any knowledge about storage.
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void resetMemory() { m_memoryContent.clear(); }
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/// Resets any knowledge about the current stack.
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void resetStack() { m_stackElements.clear(); m_stackHeight = 0; }
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/// Resets any knowledge.
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void reset() { resetStorage(); resetMemory(); resetStack(); }
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unsigned sequenceNumber() const { return m_sequenceNumber; }
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/// Manually increments the storage and memory sequence number.
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void incrementSequenceNumber() { m_sequenceNumber += 2; }
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/// Replaces the state by the intersection with _other, i.e. only equal knowledge is retained.
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/// If the stack heighht is different, the smaller one is used and the stack is compared
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/// relatively.
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void reduceToCommonKnowledge(KnownState const& _other);
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/// @returns a shared pointer to a copy of this state.
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std::shared_ptr<KnownState> copy() const { return std::make_shared<KnownState>(*this); }
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/// @returns true if the knowledge about the state of both objects is (known to be) equal.
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bool operator==(KnownState const& _other) const;
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/// Retrieves the current equivalence class fo the given stack element (or generates a new
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/// one if it does not exist yet).
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Id stackElement(int _stackHeight, SourceLocation const& _location);
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/// @returns the stackElement relative to the current stack height.
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Id relativeStackElement(int _stackOffset, SourceLocation const& _location = SourceLocation());
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/// @returns its set of tags if the given expression class is a known tag union; returns a set
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/// containing the tag if it is a PushTag expression and the empty set otherwise.
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std::set<u256> tagsInExpression(Id _expressionId);
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/// During analysis, different tags on the stack are partially treated as the same class.
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/// This removes such classes not to confuse later analyzers.
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void clearTagUnions();
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int stackHeight() const { return m_stackHeight; }
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std::map<int, Id> const& stackElements() const { return m_stackElements; }
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ExpressionClasses& expressionClasses() const { return *m_expressionClasses; }
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std::map<Id, Id> const& storageContent() const { return m_storageContent; }
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private:
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/// Assigns a new equivalence class to the next sequence number of the given stack element.
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void setStackElement(int _stackHeight, Id _class);
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/// Swaps the given stack elements in their next sequence number.
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void swapStackElements(int _stackHeightA, int _stackHeightB, SourceLocation const& _location);
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/// Increments the sequence number, deletes all storage information that might be overwritten
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/// and stores the new value at the given slot.
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/// @returns the store operation, which might be invalid if storage was not modified
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StoreOperation storeInStorage(Id _slot, Id _value, SourceLocation const& _location);
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/// Retrieves the current value at the given slot in storage or creates a new special sload class.
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Id loadFromStorage(Id _slot, SourceLocation const& _location);
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/// Increments the sequence number, deletes all memory information that might be overwritten
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/// and stores the new value at the given slot.
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/// @returns the store operation, which might be invalid if memory was not modified
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StoreOperation storeInMemory(Id _slot, Id _value, SourceLocation const& _location);
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/// Retrieves the current value at the given slot in memory or creates a new special mload class.
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Id loadFromMemory(Id _slot, SourceLocation const& _location);
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/// Finds or creates a new expression that applies the sha3 hash function to the contents in memory.
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Id applySha3(Id _start, Id _length, SourceLocation const& _location);
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/// @returns a new or already used Id representing the given set of tags.
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Id tagUnion(std::set<u256> _tags);
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/// Current stack height, can be negative.
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int m_stackHeight = 0;
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/// Current stack layout, mapping stack height -> equivalence class
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std::map<int, Id> m_stackElements;
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/// Current sequence number, this is incremented with each modification to storage or memory.
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unsigned m_sequenceNumber = 1;
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/// Knowledge about storage content.
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std::map<Id, Id> m_storageContent;
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/// Knowledge about memory content. Keys are memory addresses, note that the values overlap
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/// and are not contained here if they are not completely known.
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std::map<Id, Id> m_memoryContent;
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/// Keeps record of all sha3 hashes that are computed.
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std::map<std::vector<Id>, Id> m_knownSha3Hashes;
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/// Structure containing the classes of equivalent expressions.
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std::shared_ptr<ExpressionClasses> m_expressionClasses;
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/// Container for unions of tags stored on the stack.
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boost::bimap<Id, std::set<u256>> m_tagUnions;
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};
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}
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}
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