/*
* The following code is adapted from code originally written by Bjoern
* Hoehrmann <bjoern@hoehrmann.de>. See
* http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
*
* The original license:
*
* Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
/*
* IXUtf8Validator.h
* Author: Benjamin Sergeant
* Copyright (c) 2019 Machine Zone, Inc. All rights reserved.
*
* From websocketpp. Tiny modifications made for code style, function names etc...
*/
#pragma once
#include <cstdint>
#include <string>
namespace ix
{
/// State that represents a valid utf8 input sequence
static unsigned int const utf8_accept = 0;
/// State that represents an invalid utf8 input sequence
static unsigned int const utf8_reject = 1;
/// Lookup table for the UTF8 decode state machine
static uint8_t const utf8d[] = {
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 00..1f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 20..3f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 40..5f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 60..7f
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, // 80..9f
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, // a0..bf
8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, // c0..df
0xa,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x4,0x3,0x3, // e0..ef
0xb,0x6,0x6,0x6,0x5,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8, // f0..ff
0x0,0x1,0x2,0x3,0x5,0x8,0x7,0x1,0x1,0x1,0x4,0x6,0x1,0x1,0x1,0x1, // s0..s0
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,0,1,0,1,1,1,1,1,1, // s1..s2
1,2,1,1,1,1,1,2,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1, // s3..s4
1,2,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,3,1,1,1,1,1,1, // s5..s6
1,3,1,1,1,1,1,3,1,3,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // s7..s8
};
/// Decode the next byte of a UTF8 sequence
/**
* @param [out] state The decoder state to advance
* @param [out] codep The codepoint to fill in
* @param [in] byte The byte to input
* @return The ending state of the decode operation
*/
inline uint32_t decodeNextByte(uint32_t * state, uint32_t * codep, uint8_t byte)
{
uint32_t type = utf8d[byte];
*codep = (*state != utf8_accept) ?
(byte & 0x3fu) | (*codep << 6) :
(0xff >> type) & (byte);
*state = utf8d[256 + *state*16 + type];
return *state;
}
/// Provides streaming UTF8 validation functionality
class Utf8Validator
{
public:
/// Construct and initialize the validator
Utf8Validator() : m_state(utf8_accept),m_codepoint(0) {}
/// Advance the state of the validator with the next input byte
/**
* @param byte The byte to advance the validation state with
* @return Whether or not the byte resulted in a validation error.
*/
bool consume(uint8_t byte)
{
if (decodeNextByte(&m_state,&m_codepoint,byte) == utf8_reject)
{
return false;
}
return true;
}
/// Advance Validator state with input from an iterator pair
/**
* @param begin Input iterator to the start of the input range
* @param end Input iterator to the end of the input range
* @return Whether or not decoding the bytes resulted in a validation error.
*/
template <typename iterator_type>
bool decode(iterator_type begin, iterator_type end)
{
for (iterator_type it = begin; it != end; ++it)
{
unsigned int result = decodeNextByte(
&m_state,
&m_codepoint,
static_cast<uint8_t>(*it)
);
if (result == utf8_reject)
{
return false;
}
}
return true;
}
/// Return whether the input sequence ended on a valid utf8 codepoint
/**
* @return Whether or not the input sequence ended on a valid codepoint.
*/
bool complete()
{
return m_state == utf8_accept;
}
/// Reset the Validator to decode another message
void reset()
{
m_state = utf8_accept;
m_codepoint = 0;
}
private:
uint32_t m_state;
uint32_t m_codepoint;
};
/// Validate a UTF8 string
/**
* convenience function that creates a Validator, validates a complete string
* and returns the result.
*/
inline bool validateUtf8(std::string const & s)
{
Utf8Validator v;
if (!v.decode(s.begin(),s.end()))
{
return false;
}
return v.complete();
}
} // namespace ix