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(); } 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) { 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; } else 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; } } // 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; } }