| // Copyright 2016 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef QUICHE_HTTP2_HPACK_DECODER_HPACK_DECODER_STRING_BUFFER_H_ |
| #define QUICHE_HTTP2_HPACK_DECODER_HPACK_DECODER_STRING_BUFFER_H_ |
| |
| // HpackDecoderStringBuffer helps an HPACK decoder to avoid copies of a string |
| // literal (name or value) except when necessary (e.g. when split across two |
| // or more HPACK block fragments). |
| |
| #include <stddef.h> |
| |
| #include <ostream> |
| #include <string> |
| |
| #include "absl/strings/string_view.h" |
| #include "quiche/http2/hpack/huffman/hpack_huffman_decoder.h" |
| #include "quiche/common/platform/api/quiche_export.h" |
| |
| namespace http2 { |
| |
| class QUICHE_EXPORT HpackDecoderStringBuffer { |
| public: |
| enum class State : uint8_t { RESET, COLLECTING, COMPLETE }; |
| enum class Backing : uint8_t { RESET, UNBUFFERED, BUFFERED }; |
| |
| HpackDecoderStringBuffer(); |
| ~HpackDecoderStringBuffer(); |
| |
| HpackDecoderStringBuffer(const HpackDecoderStringBuffer&) = delete; |
| HpackDecoderStringBuffer& operator=(const HpackDecoderStringBuffer&) = delete; |
| |
| void Reset(); |
| |
| // Note that for Huffman encoded strings the length of the string after |
| // decoding may be larger (expected), the same or even smaller; the latter |
| // are unlikely, but possible if the encoder makes odd choices. |
| void OnStart(bool huffman_encoded, size_t len); |
| bool OnData(const char* data, size_t len); |
| bool OnEnd(); |
| void BufferStringIfUnbuffered(); |
| bool IsBuffered() const; |
| size_t BufferedLength() const; |
| |
| // Accessors for the completely collected string (i.e. Set or OnEnd has just |
| // been called, and no reset of the state has occurred). |
| |
| // Returns a string_view pointing to the backing store for the string, |
| // either the internal buffer or the original transport buffer (e.g. for a |
| // literal value that wasn't Huffman encoded, and that wasn't split across |
| // transport buffers). |
| absl::string_view str() const; |
| |
| // Same as str() if state_ is COMPLETE. Otherwise, returns empty string piece. |
| absl::string_view GetStringIfComplete() const; |
| |
| // Returns the completely collected string by value, using std::move in an |
| // effort to avoid unnecessary copies. ReleaseString() must not be called |
| // unless the string has been buffered (to avoid forcing a potentially |
| // unnecessary copy). ReleaseString() also resets the instance so that it can |
| // be used to collect another string. |
| std::string ReleaseString(); |
| |
| State state_for_testing() const { return state_; } |
| Backing backing_for_testing() const { return backing_; } |
| void OutputDebugStringTo(std::ostream& out) const; |
| |
| private: |
| // Storage for the string being buffered, if buffering is necessary |
| // (e.g. if Huffman encoded, buffer_ is storage for the decoded string). |
| std::string buffer_; |
| |
| // The string_view to be returned by HpackDecoderStringBuffer::str(). If |
| // a string has been collected, but not buffered, value_ points to that |
| // string. |
| absl::string_view value_; |
| |
| // The decoder to use if the string is Huffman encoded. |
| HpackHuffmanDecoder decoder_; |
| |
| // Count of bytes not yet passed to OnData. |
| size_t remaining_len_; |
| |
| // Is the HPACK string Huffman encoded? |
| bool is_huffman_encoded_; |
| |
| // State of the string decoding process. |
| State state_; |
| |
| // Where is the string stored? |
| Backing backing_; |
| }; |
| |
| QUICHE_EXPORT std::ostream& operator<<(std::ostream& out, |
| const HpackDecoderStringBuffer& v); |
| |
| } // namespace http2 |
| |
| #endif // QUICHE_HTTP2_HPACK_DECODER_HPACK_DECODER_STRING_BUFFER_H_ |