/** * Copyright (C) 2015 Topology LP * Copyright (C) 2013 Adam Rudd (bit calculations) * Copyright (C) 2018 Jakob Petsovits * All rights reserved. * * 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. * * Bit calculations adapted from https://github.com/adamvr/arduino-base64, * commit 999595783185a0afcba156d7276dfeaa9cb5382f. */ #ifndef CPPCODEC_DETAIL_BASE64 #define CPPCODEC_DETAIL_BASE64 #include <stdexcept> #include <stdint.h> #include "../data/access.hpp" #include "../parse_error.hpp" #include "config.hpp" #include "stream_codec.hpp" namespace cppcodec { namespace detail { template <typename CodecVariant> class base64 : public CodecVariant::template codec_impl<base64<CodecVariant>> { public: static inline constexpr uint8_t binary_block_size() { return 3; } static inline constexpr uint8_t encoded_block_size() { return 4; } static CPPCODEC_ALWAYS_INLINE constexpr uint8_t num_encoded_tail_symbols(uint8_t num_bytes) { return (num_bytes == 1) ? 2 // 2 symbols, 2 padding characters : (num_bytes == 2) ? 3 // 3 symbols, 1 padding character : throw std::domain_error("invalid number of bytes in a tail block"); } template <uint8_t I> static CPPCODEC_ALWAYS_INLINE constexpr uint8_t index( const uint8_t* b /*binary block*/) noexcept { static_assert(I >= 0 && I < encoded_block_size(), "invalid encoding symbol index in a block"); return (I == 0) ? (b[0] >> 2) // first 6 bits : (I == 1) ? (((b[0] & 0x3) << 4) | (b[1] >> 4)) : (I == 2) ? (((b[1] & 0xF) << 2) | (b[2] >> 6)) : /*I == 3*/ (b[2] & 0x3F); // last 6 bits } template <bool B> using uint8_if = typename std::enable_if<B, uint8_t>::type; template <uint8_t I> static CPPCODEC_ALWAYS_INLINE constexpr uint8_if<I == 1 || I == 2> index_last( const uint8_t* b /*binary block*/) noexcept { return (I == 1) ? ((b[0] & 0x3) << 4) // abbreviated 2nd symbol : /*I == 2*/ ((b[1] & 0xF) << 2); // abbreviated 3rd symbol } template <uint8_t I> static CPPCODEC_ALWAYS_INLINE uint8_if<I != 1 && I != 2> index_last( const uint8_t* /*binary block*/) { throw std::domain_error("invalid last encoding symbol index in a tail"); } template <typename Result, typename ResultState> static CPPCODEC_ALWAYS_INLINE void decode_block( Result& decoded, ResultState&, const alphabet_index_t* idx); template <typename Result, typename ResultState> static CPPCODEC_ALWAYS_INLINE void decode_tail( Result& decoded, ResultState&, const alphabet_index_t* idx, size_t idx_len); }; template <typename CodecVariant> template <typename Result, typename ResultState> CPPCODEC_ALWAYS_INLINE void base64<CodecVariant>::decode_block( Result& decoded, ResultState& state, const alphabet_index_t* idx) { uint_fast32_t dec = (idx[0] << 18) | (idx[1] << 12) | (idx[2] << 6) | idx[3]; data::put(decoded, state, static_cast<uint8_t>(dec >> 16)); data::put(decoded, state, static_cast<uint8_t>((dec >> 8) & 0xFF)); data::put(decoded, state, static_cast<uint8_t>(dec & 0xFF)); } template <typename CodecVariant> template <typename Result, typename ResultState> CPPCODEC_ALWAYS_INLINE void base64<CodecVariant>::decode_tail( Result& decoded, ResultState& state, const alphabet_index_t* idx, size_t idx_len) { if (idx_len == 1) { throw invalid_input_length( "invalid number of symbols in last base64 block: found 1, expected 2 or 3"); } // idx_len == 2: decoded size 1 data::put(decoded, state, static_cast<uint8_t>((idx[0] << 2) + ((idx[1] & 0x30) >> 4))); if (idx_len == 2) { return; } // idx_len == 3: decoded size 2 data::put(decoded, state, static_cast<uint8_t>(((idx[1] & 0xF) << 4) + ((idx[2] & 0x3C) >> 2))); } } // namespace detail } // namespace cppcodec #endif // CPPCODEC_DETAIL_BASE64