1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef QUICHE_SPDY_CORE_HPACK_HPACK_OUTPUT_STREAM_H_ 6 #define QUICHE_SPDY_CORE_HPACK_HPACK_OUTPUT_STREAM_H_ 7 8 #include <cstddef> 9 #include <cstdint> 10 #include <string> 11 12 #include "absl/strings/string_view.h" 13 #include "quiche/common/platform/api/quiche_export.h" 14 #include "quiche/spdy/core/hpack/hpack_constants.h" 15 16 // All section references below are to 17 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-08 18 19 namespace spdy { 20 21 // An HpackOutputStream handles all the low-level details of encoding 22 // header fields. 23 class QUICHE_EXPORT HpackOutputStream { 24 public: 25 HpackOutputStream(); 26 HpackOutputStream(const HpackOutputStream&) = delete; 27 HpackOutputStream& operator=(const HpackOutputStream&) = delete; 28 ~HpackOutputStream(); 29 30 // Appends the lower |bit_size| bits of |bits| to the internal buffer. 31 // 32 // |bit_size| must be > 0 and <= 8. |bits| must not have any bits 33 // set other than the lower |bit_size| bits. 34 void AppendBits(uint8_t bits, size_t bit_size); 35 36 // Simply forwards to AppendBits(prefix.bits, prefix.bit-size). 37 void AppendPrefix(HpackPrefix prefix); 38 39 // Directly appends |buffer|. 40 void AppendBytes(absl::string_view buffer); 41 42 // Appends the given integer using the representation described in 43 // 6.1. If the internal buffer ends on a byte boundary, the prefix 44 // length N is taken to be 8; otherwise, it is taken to be the 45 // number of bits to the next byte boundary. 46 // 47 // It is guaranteed that the internal buffer will end on a byte 48 // boundary after this function is called. 49 void AppendUint32(uint32_t I); 50 51 // Return pointer to internal buffer. |bit_offset_| needs to be zero. 52 std::string* MutableString(); 53 54 // Returns the internal buffer as a string, then resets state. 55 std::string TakeString(); 56 57 // Returns up to |max_size| bytes of the internal buffer. Resets 58 // internal state with the overflow. 59 std::string BoundedTakeString(size_t max_size); 60 61 // Size in bytes of stream's internal buffer. size()62 size_t size() const { return buffer_.size(); } 63 64 private: 65 // The internal bit buffer. 66 std::string buffer_; 67 68 // If 0, the buffer ends on a byte boundary. If non-zero, the buffer 69 // ends on the nth most significant bit. Guaranteed to be < 8. 70 size_t bit_offset_; 71 }; 72 73 } // namespace spdy 74 75 #endif // QUICHE_SPDY_CORE_HPACK_HPACK_OUTPUT_STREAM_H_ 76