pragma solidity ^0.4.6;
/**
* @title RLPReader
*
* RLPReader is used to read and parse RLP encoded data in memory.
*
* @author Andreas Olofsson (androlo1980@gmail.com)
*/
library RLP {
uint constant DATA_SHORT_START = 0x80;
uint constant DATA_LONG_START = 0xB8;
uint constant LIST_SHORT_START = 0xC0;
uint constant LIST_LONG_START = 0xF8;
uint constant DATA_LONG_OFFSET = 0xB7;
uint constant LIST_LONG_OFFSET = 0xF7;
struct RLPItem {
uint _unsafe_memPtr; // Pointer to the RLP-encoded bytes.
uint _unsafe_length; // Number of bytes. This is the full length of the string.
}
struct Iterator {
RLPItem _unsafe_item; // Item that's being iterated over.
uint _unsafe_nextPtr; // Position of the next item in the list.
}
/* Iterator */
function next(Iterator memory self) internal view returns (RLPItem memory subItem) {
if(hasNext(self)) {
uint ptr = self._unsafe_nextPtr;
uint itemLength = _itemLength(ptr);
subItem._unsafe_memPtr = ptr;
subItem._unsafe_length = itemLength;
self._unsafe_nextPtr = ptr + itemLength;
}
else
revert();
}
function next(Iterator memory self, bool strict) internal view returns (RLPItem memory subItem) {
subItem = next(self);
if(strict && !_validate(subItem))
revert();
return;
}
function hasNext(Iterator memory self) internal view returns (bool) {
RLPItem memory item = self._unsafe_item;
return self._unsafe_nextPtr < item._unsafe_memPtr + item._unsafe_length;
}
/* RLPItem */
/// @dev Creates an RLPItem from an array of RLP encoded bytes.
/// @param self The RLP encoded bytes.
/// @return An RLPItem
function toRLPItem(bytes memory self) internal view returns (RLPItem memory) {
uint len = self.length;
if (len == 0) {
return RLPItem(0, 0);
}
uint memPtr;
assembly {
memPtr := add(self, 0x20)
}
return RLPItem(memPtr, len);
}
/// @dev Creates an RLPItem from an array of RLP encoded bytes.
/// @param self The RLP encoded bytes.
/// @param strict Will throw if the data is not RLP encoded.
/// @return An RLPItem
function toRLPItem(bytes memory self, bool strict) internal view returns (RLPItem memory) {
RLPItem memory item = toRLPItem(self);
if(strict) {
uint len = self.length;
if(_payloadOffset(item) > len)
revert();
if(_itemLength(item._unsafe_memPtr) != len)
revert();
if(!_validate(item))
revert();
}
return item;
}
/// @dev Check if the RLP item is null.
/// @param self The RLP item.
/// @return 'true' if the item is null.
function isNull(RLPItem memory self) internal view returns (bool ret) {
return self._unsafe_length == 0;
}
/// @dev Check if the RLP item is a list.
/// @param self The RLP item.
/// @return 'true' if the item is a list.
function isList(RLPItem memory self) internal view returns (bool ret) {
if (self._unsafe_length == 0)
return false;
uint memPtr = self._unsafe_memPtr;
assembly {
ret := iszero(lt(byte(0, mload(memPtr)), 0xC0))
}
}
/// @dev Check if the RLP item is data.
/// @param self The RLP item.
/// @return 'true' if the item is data.
function isData(RLPItem memory self) internal view returns (bool ret) {
if (self._unsafe_length == 0)
return false;
uint memPtr = self._unsafe_memPtr;
assembly {
ret := lt(byte(0, mload(memPtr)), 0xC0)
}
}
/// @dev Check if the RLP item is empty (string or list).
/// @param self The RLP item.
/// @return 'true' if the item is null.
function isEmpty(RLPItem memory self) internal view returns (bool ret) {
if(isNull(self))
return false;
uint b0;
uint memPtr = self._unsafe_memPtr;
assembly {
b0 := byte(0, mload(memPtr))
}
return (b0 == DATA_SHORT_START || b0 == LIST_SHORT_START);
}
/// @dev Get the number of items in an RLP encoded list.
/// @param self The RLP item.
/// @return The number of items.
function items(RLPItem memory self) internal view returns (uint) {
if (!isList(self))
return 0;
uint b0;
uint memPtr = self._unsafe_memPtr;
assembly {
b0 := byte(0, mload(memPtr))
}
uint pos = memPtr + _payloadOffset(self);
uint last = memPtr + self._unsafe_length - 1;
uint itms;
while(pos <= last) {
pos += _itemLength(pos);
itms++;
}
return itms;
}
/// @dev Create an iterator.
/// @param self The RLP item.
/// @return An 'Iterator' over the item.
function iterator(RLPItem memory self) internal view returns (Iterator memory it) {
if (!isList(self))
revert();
uint ptr = self._unsafe_memPtr + _payloadOffset(self);
it._unsafe_item = self;
it._unsafe_nextPtr = ptr;
}
/// @dev Return the RLP encoded bytes.
/// @param self The RLPItem.
/// @return The bytes.
function toBytes(RLPItem memory self) internal returns (bytes memory bts) {
uint len = self._unsafe_length;
if (len == 0)
return;
bts = new bytes(len);
_copyToBytes(self._unsafe_memPtr, bts, len);
}
/// @dev Decode an RLPItem into bytes. This will not work if the
/// RLPItem is a list.
/// @param self The RLPItem.
/// @return The decoded string.
function toData(RLPItem memory self) internal returns (bytes memory bts) {
if(!isData(self))
revert();
(uint rStartPos, uint len) = _decode(self);
bts = new bytes(len);
_copyToBytes(rStartPos, bts, len);
}
/// @dev Get the list of sub-items from an RLP encoded list.
/// Warning: This is inefficient, as it requires that the list is read twice.
/// @param self The RLP item.
/// @return Array of RLPItems.
function toList(RLPItem memory self) internal view returns (RLPItem[] memory list) {
if(!isList(self))
revert();
uint numItems = items(self);
list = new RLPItem[](numItems);
Iterator memory it = iterator(self);
uint idx;
while(hasNext(it)) {
list[idx] = next(it);
idx++;
}
}
/// @dev Decode an RLPItem into an ascii string. This will not work if the
/// RLPItem is a list.
/// @param self The RLPItem.
/// @return The decoded string.
function toAscii(RLPItem memory self) internal returns (string memory str) {
if(!isData(self))
revert();
(uint rStartPos, uint len) = _decode(self);
bytes memory bts = new bytes(len);
_copyToBytes(rStartPos, bts, len);
str = string(bts);
}
/// @dev Decode an RLPItem into a uint. This will not work if the
/// RLPItem is a list.
/// @param self The RLPItem.
/// @return The decoded string.
function toUint(RLPItem memory self) internal view returns (uint data) {
if(!isData(self))
revert();
(uint rStartPos, uint len) = _decode(self);
if (len > 32 || len == 0)
revert();
assembly {
data := div(mload(rStartPos), exp(256, sub(32, len)))
}
}
/// @dev Decode an RLPItem into a boolean. This will not work if the
/// RLPItem is a list.
/// @param self The RLPItem.
/// @return The decoded string.
function toBool(RLPItem memory self) internal view returns (bool data) {
if(!isData(self))
revert();
(uint rStartPos, uint len) = _decode(self);
if (len != 1)
revert();
uint temp;
assembly {
temp := byte(0, mload(rStartPos))
}
if (temp > 1)
revert();
return temp == 1 ? true : false;
}
/// @dev Decode an RLPItem into a byte. This will not work if the
/// RLPItem is a list.
/// @param self The RLPItem.
/// @return The decoded string.
function toByte(RLPItem memory self) internal view returns (byte data) {
if(!isData(self))
revert();
(uint rStartPos, uint len) = _decode(self);
if (len != 1)
revert();
uint8 temp;
assembly {
temp := byte(0, mload(rStartPos))
}
return byte(temp);
}
/// @dev Decode an RLPItem into an int. This will not work if the
/// RLPItem is a list.
/// @param self The RLPItem.
/// @return The decoded string.
function toInt(RLPItem memory self) internal view returns (int data) {
return int(toUint(self));
}
/// @dev Decode an RLPItem into a bytes32. This will not work if the
/// RLPItem is a list.
/// @param self The RLPItem.
/// @return The decoded string.
function toBytes32(RLPItem memory self) internal view returns (bytes32 data) {
return bytes32(toUint(self));
}
/// @dev Decode an RLPItem into an address. This will not work if the
/// RLPItem is a list.
/// @param self The RLPItem.
/// @return The decoded string.
function toAddress(RLPItem memory self) internal view returns (address data) {
if(!isData(self))
revert();
(uint rStartPos, uint len) = _decode(self);
if (len != 20)
revert();
assembly {
data := div(mload(rStartPos), exp(256, 12))
}
}
// Get the payload offset.
function _payloadOffset(RLPItem memory self) private view returns (uint) {
if(self._unsafe_length == 0)
return 0;
uint b0;
uint memPtr = self._unsafe_memPtr;
assembly {
b0 := byte(0, mload(memPtr))
}
if(b0 < DATA_SHORT_START)
return 0;
if(b0 < DATA_LONG_START || (b0 >= LIST_SHORT_START && b0 < LIST_LONG_START))
return 1;
if(b0 < LIST_SHORT_START)
return b0 - DATA_LONG_OFFSET + 1;
return b0 - LIST_LONG_OFFSET + 1;
}
// Get the full length of an RLP item.
function _itemLength(uint memPtr) private view returns (uint len) {
uint b0;
assembly {
b0 := byte(0, mload(memPtr))
}
if (b0 < DATA_SHORT_START)
len = 1;
else if (b0 < DATA_LONG_START)
len = b0 - DATA_SHORT_START + 1;
else if (b0 < LIST_SHORT_START) {
assembly {
let bLen := sub(b0, 0xB7) // bytes length (DATA_LONG_OFFSET)
let dLen := div(mload(add(memPtr, 1)), exp(256, sub(32, bLen))) // data length
len := add(1, add(bLen, dLen)) // total length
}
}
else if (b0 < LIST_LONG_START)
len = b0 - LIST_SHORT_START + 1;
else {
assembly {
let bLen := sub(b0, 0xF7) // bytes length (LIST_LONG_OFFSET)
let dLen := div(mload(add(memPtr, 1)), exp(256, sub(32, bLen))) // data length
len := add(1, add(bLen, dLen)) // total length
}
}
}
// Get start position and length of the data.
function _decode(RLPItem memory self) private view returns (uint memPtr, uint len) {
if(!isData(self))
revert();
uint b0;
uint start = self._unsafe_memPtr;
assembly {
b0 := byte(0, mload(start))
}
if (b0 < DATA_SHORT_START) {
memPtr = start;
len = 1;
return;
}
if (b0 < DATA_LONG_START) {
len = self._unsafe_length - 1;
memPtr = start + 1;
} else {
uint bLen;
assembly {
bLen := sub(b0, 0xB7) // DATA_LONG_OFFSET
}
len = self._unsafe_length - 1 - bLen;
memPtr = start + bLen + 1;
}
return;
}
// Assumes that enough memory has been allocated to store in target.
function _copyToBytes(uint btsPtr, bytes memory tgt, uint btsLen) private {
// Exploiting the fact that 'tgt' was the last thing to be allocated,
// we can write entire words, and just overwrite any excess.
assembly {
{
let words := div(add(btsLen, 31), 32)
let rOffset := btsPtr
let wOffset := add(tgt, 0x20)
// Start at arr + 0x20
for { let i := 0 } not(eq(i, words)) { i := add(i, 1) }
{
let offset := mul(i, 0x20)
mstore(add(wOffset, offset), mload(add(rOffset, offset)))
}
mstore(add(tgt, add(0x20, mload(tgt))), 0)
}
}
}
// Check that an RLP item is valid.
function _validate(RLPItem memory self) private view returns (bool ret) {
// Check that RLP is well-formed.
uint b0;
uint b1;
uint memPtr = self._unsafe_memPtr;
assembly {
b0 := byte(0, mload(memPtr))
b1 := byte(1, mload(memPtr))
}
if(b0 == DATA_SHORT_START + 1 && b1 < DATA_SHORT_START)
return false;
return true;
}
}
