RLP.cpp

/*
	This file is part of cpp-ethereum.

	cpp-ethereum is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	cpp-ethereum is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file RLP.cpp
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#include "RLP.h"
using namespace std;
using namespace dev;

RLP::RLP(bytesConstRef _d, Strictness _s):
	m_data(_d)
{
	if ((_s & FailIfTooBig) && actualSize() < _d.size())
	{
		if (_s & ThrowOnFail)
			BOOST_THROW_EXCEPTION(OversizeRLP());
		else
			m_data.reset();
	}
	if ((_s & FailIfTooSmall) && actualSize() > _d.size())
	{
		if (_s & ThrowOnFail)
			BOOST_THROW_EXCEPTION(UndersizeRLP());
		else
			m_data.reset();
	}
}

RLP::iterator& RLP::iterator::operator++()
{
	if (m_remaining)
	{
		m_currentItem.retarget(m_currentItem.next().data(), m_remaining);
		m_currentItem = m_currentItem.cropped(0, sizeAsEncoded(m_currentItem));
		m_remaining -= std::min<size_t>(m_remaining, m_currentItem.size());
	}
	else
		m_currentItem.retarget(m_currentItem.next().data(), 0);
	return *this;
}

RLP::iterator::iterator(RLP const& _parent, bool _begin)
{
	if (_begin && _parent.isList())
	{
		auto pl = _parent.payload();
		m_currentItem = pl.cropped(0, sizeAsEncoded(pl));
		m_remaining = pl.size() - m_currentItem.size();
	}
	else
	{
		m_currentItem = _parent.data().cropped(_parent.data().size());
		m_remaining = 0;
	}
}

RLP RLP::operator[](size_t _i) const
{
	if (_i < m_lastIndex)
	{
		m_lastEnd = sizeAsEncoded(payload());
		m_lastItem = payload().cropped(0, m_lastEnd);
		m_lastIndex = 0;
	}
	for (; m_lastIndex < _i && m_lastItem.size(); ++m_lastIndex)
	{
		m_lastItem = payload().cropped(m_lastEnd);
		m_lastItem = m_lastItem.cropped(0, sizeAsEncoded(m_lastItem));
		m_lastEnd += m_lastItem.size();
	}
	return RLP(m_lastItem, ThrowOnFail | FailIfTooSmall);
}

RLPs RLP::toList() const
{
	RLPs ret;
	if (!isList())
		return ret;
	for (auto const& i: *this)
		ret.push_back(i);
	return ret;
}

size_t RLP::actualSize() const
{
	if (isNull())
		return 0;
	if (isSingleByte())
		return 1;
	if (isData() || isList())
		return payloadOffset() + length();
	return 0;
}

void RLP::requireGood() const
{
	if (isNull())
		BOOST_THROW_EXCEPTION(BadRLP());
	byte n = m_data[0];
	if (n != c_rlpDataImmLenStart + 1)
		return;
	if (m_data.size() < 2)
		BOOST_THROW_EXCEPTION(BadRLP());
	if (m_data[1] < c_rlpDataImmLenStart)
		BOOST_THROW_EXCEPTION(BadRLP());
}

bool RLP::isInt() const
{
	if (isNull())
		return false;
	requireGood();
	byte n = m_data[0];
	if (n < c_rlpDataImmLenStart)
		return n != 0;
	else if (n == c_rlpDataImmLenStart)
		return true;
	else if (n <= c_rlpDataIndLenZero)
	{
		if (m_data.size() <= 1)
			BOOST_THROW_EXCEPTION(BadRLP());
		return m_data[1] != 0;
	}
	else if (n < c_rlpListStart)
	{
		if (m_data.size() <= size_t(1 + n - c_rlpDataIndLenZero))
			BOOST_THROW_EXCEPTION(BadRLP());
		return m_data[1 + n - c_rlpDataIndLenZero] != 0;
	}
	return false;
}

size_t RLP::length() const
{
	if (isNull())
		return 0;
	requireGood();
	size_t ret = 0;
	byte const n = m_data[0];
	if (n < c_rlpDataImmLenStart)
		return 1;
	else if (n <= c_rlpDataIndLenZero)
		return n - c_rlpDataImmLenStart;
	else if (n < c_rlpListStart)
	{
		if (m_data.size() <= size_t(n - c_rlpDataIndLenZero))
			BOOST_THROW_EXCEPTION(BadRLP());
		if (m_data.size() > 1)
			if (m_data[1] == 0)
				BOOST_THROW_EXCEPTION(BadRLP());
		unsigned lengthSize = n - c_rlpDataIndLenZero;
		if (lengthSize > sizeof(ret))
			// We did not check, but would most probably not fit in our memory.
			BOOST_THROW_EXCEPTION(UndersizeRLP());
		// No leading zeroes.
		if (!m_data[1])
			BOOST_THROW_EXCEPTION(BadRLP());
		for (unsigned i = 0; i < lengthSize; ++i)
			ret = (ret << 8) | m_data[i + 1];
		// Must be greater than the limit.
		if (ret < c_rlpListStart - c_rlpDataImmLenStart - c_rlpMaxLengthBytes)
			BOOST_THROW_EXCEPTION(BadRLP());
	}
	else if (n <= c_rlpListIndLenZero)
		return n - c_rlpListStart;
	else
	{
		unsigned lengthSize = n - c_rlpListIndLenZero;
		if (m_data.size() <= lengthSize)
			BOOST_THROW_EXCEPTION(BadRLP());
		if (m_data.size() > 1)
			if (m_data[1] == 0)
				BOOST_THROW_EXCEPTION(BadRLP());
		if (lengthSize > sizeof(ret))
			// We did not check, but would most probably not fit in our memory.
			BOOST_THROW_EXCEPTION(UndersizeRLP());
		if (!m_data[1])
			BOOST_THROW_EXCEPTION(BadRLP());
		for (unsigned i = 0; i < lengthSize; ++i)
			ret = (ret << 8) | m_data[i + 1];
		if (ret < 0x100 - c_rlpListStart - c_rlpMaxLengthBytes)
			BOOST_THROW_EXCEPTION(BadRLP());
	}
	// We have to be able to add payloadOffset to length without overflow.
	// This rejects roughly 4GB-sized RLPs on some platforms.
	if (ret >= std::numeric_limits<size_t>::max() - 0x100)
		BOOST_THROW_EXCEPTION(UndersizeRLP());
	return ret;
}

size_t RLP::items() const
{
	if (isList())
	{
		bytesConstRef d = payload();
		size_t i = 0;
		for (; d.size(); ++i)
			d = d.cropped(sizeAsEncoded(d));
		return i;
	}
	return 0;
}

RLPStream& RLPStream::appendRaw(bytesConstRef _s, size_t _itemCount)
{
	m_out.insert(m_out.end(), _s.begin(), _s.end());
	noteAppended(_itemCount);
	return *this;
}

void RLPStream::noteAppended(size_t _itemCount)
{
	if (!_itemCount)
		return;
//	cdebug << "noteAppended(" << _itemCount << ")";
	while (m_listStack.size())
	{
		if (m_listStack.back().first < _itemCount)
			BOOST_THROW_EXCEPTION(RLPException() << errinfo_comment("itemCount too large") << RequirementError((bigint)m_listStack.back().first, (bigint)_itemCount));
		m_listStack.back().first -= _itemCount;
		if (m_listStack.back().first)
			break;
		else
		{
			auto p = m_listStack.back().second;
			m_listStack.pop_back();
			size_t s = m_out.size() - p;		// list size
			auto brs = bytesRequired(s);
			unsigned encodeSize = s < c_rlpListImmLenCount ? 1 : (1 + brs);
//			cdebug << "s: " << s << ", p: " << p << ", m_out.size(): " << m_out.size() << ", encodeSize: " << encodeSize << " (br: " << brs << ")";
			auto os = m_out.size();
			m_out.resize(os + encodeSize);
			memmove(m_out.data() + p + encodeSize, m_out.data() + p, os - p);
			if (s < c_rlpListImmLenCount)
				m_out[p] = (byte)(c_rlpListStart + s);
			else if (c_rlpListIndLenZero + brs <= 0xff)
			{
				m_out[p] = (byte)(c_rlpListIndLenZero + brs);
				byte* b = &(m_out[p + brs]);
				for (; s; s >>= 8)
					*(b--) = (byte)s;
			}
			else
				BOOST_THROW_EXCEPTION(RLPException() << errinfo_comment("itemCount too large for RLP"));
		}
		_itemCount = 1;	// for all following iterations, we've effectively appended a single item only since we completed a list.
	}
}

RLPStream& RLPStream::appendList(size_t _items)
{
//	cdebug << "appendList(" << _items << ")";
	if (_items)
		m_listStack.push_back(std::make_pair(_items, m_out.size()));
	else
		appendList(bytes());
	return *this;
}

RLPStream& RLPStream::appendList(bytesConstRef _rlp)
{
	if (_rlp.size() < c_rlpListImmLenCount)
		m_out.push_back((byte)(_rlp.size() + c_rlpListStart));
	else
		pushCount(_rlp.size(), c_rlpListIndLenZero);
	appendRaw(_rlp, 1);
	return *this;
}

RLPStream& RLPStream::append(bytesConstRef _s, bool _compact)
{
	size_t s = _s.size();
	byte const* d = _s.data();
	if (_compact)
		for (size_t i = 0; i < _s.size() && !*d; ++i, --s, ++d) {}

	if (s == 1 && *d < c_rlpDataImmLenStart)
		m_out.push_back(*d);
	else
	{
		if (s < c_rlpDataImmLenCount)
			m_out.push_back((byte)(s + c_rlpDataImmLenStart));
		else
			pushCount(s, c_rlpDataIndLenZero);
		appendRaw(bytesConstRef(d, s), 0);
	}
	noteAppended();
	return *this;
}

RLPStream& RLPStream::append(bigint _i)
{
	if (!_i)
		m_out.push_back(c_rlpDataImmLenStart);
	else if (_i < c_rlpDataImmLenStart)
		m_out.push_back((byte)_i);
	else
	{
		unsigned br = bytesRequired(_i);
		if (br < c_rlpDataImmLenCount)
			m_out.push_back((byte)(br + c_rlpDataImmLenStart));
		else
		{
			auto brbr = bytesRequired(br);
			if (c_rlpDataIndLenZero + brbr > 0xff)
				BOOST_THROW_EXCEPTION(RLPException() << errinfo_comment("Number too large for RLP"));
			m_out.push_back((byte)(c_rlpDataIndLenZero + brbr));
			pushInt(br, brbr);
		}
		pushInt(_i, br);
	}
	noteAppended();
	return *this;
}

void RLPStream::pushCount(size_t _count, byte _base)
{
	auto br = bytesRequired(_count);
	if (int(br) + _base > 0xff)
		BOOST_THROW_EXCEPTION(RLPException() << errinfo_comment("Count too large for RLP"));
	m_out.push_back((byte)(br + _base));	// max 8 bytes.
	pushInt(_count, br);
}