78 lines
1.5 KiB
C++
78 lines
1.5 KiB
C++
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#pragma once
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#include <cstring>
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#include <functional>
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#include <cassert>
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#include "utils/exceptions/basic_exception.hpp"
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#include "utils/likely.hpp"
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#include "logging/default.hpp"
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namespace bolt
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{
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template <class Stream>
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class ChunkedDecoder
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{
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public:
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class DecoderError : public BasicException
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{
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public:
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using BasicException::BasicException;
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};
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using byte = unsigned char;
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ChunkedDecoder(Stream& stream) : stream(stream) {}
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/* Decode chunked data
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*
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* Chunk format looks like:
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*
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* |Header| Data ||Header| Data || ... || End |
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* | 2B | size bytes || 2B | size bytes || ... ||00 00|
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*/
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bool decode(const byte*& chunk, size_t n)
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{
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while(n > 0)
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{
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// get size from first two bytes in the chunk
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auto size = get_size(chunk);
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if(UNLIKELY(size + 2 > n))
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throw DecoderError("Chunk size larger than available data.");
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// advance chunk to pass those two bytes
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chunk += 2;
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n -= 2;
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// if chunk size is 0, we're done!
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if(size == 0)
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return true;
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stream.get().write(chunk, size);
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chunk += size;
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n -= size;
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}
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return false;
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}
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bool operator()(const byte*& chunk, size_t n)
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{
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return decode(chunk, n);
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}
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private:
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std::reference_wrapper<Stream> stream;
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size_t get_size(const byte* chunk)
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{
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return size_t(chunk[0]) << 8 | chunk[1];
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}
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};
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}
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