1 // Copyright 2016 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_HTTP2_HPACK_DECODER_HPACK_WHOLE_ENTRY_BUFFER_H_ 6 #define QUICHE_HTTP2_HPACK_DECODER_HPACK_WHOLE_ENTRY_BUFFER_H_ 7 8 // HpackWholeEntryBuffer isolates a listener from the fact that an entry may 9 // be split across multiple input buffers, providing one callback per entry. 10 // HpackWholeEntryBuffer requires that the HpackEntryDecoderListener be made in 11 // the correct order, which is tested by hpack_entry_decoder_test.cc. 12 13 #include <stddef.h> 14 15 #include "absl/strings/string_view.h" 16 #include "quiche/http2/hpack/decoder/hpack_decoder_string_buffer.h" 17 #include "quiche/http2/hpack/decoder/hpack_decoding_error.h" 18 #include "quiche/http2/hpack/decoder/hpack_entry_decoder_listener.h" 19 #include "quiche/http2/hpack/decoder/hpack_whole_entry_listener.h" 20 #include "quiche/http2/hpack/http2_hpack_constants.h" 21 #include "quiche/common/platform/api/quiche_export.h" 22 23 namespace http2 { 24 25 // TODO(jamessynge): Consider renaming HpackEntryDecoderListener to 26 // HpackEntryPartsListener or HpackEntryFragmentsListener. 27 class QUICHE_EXPORT HpackWholeEntryBuffer : public HpackEntryDecoderListener { 28 public: 29 // max_string_size specifies the maximum size of an on-the-wire string (name 30 // or value, plain or Huffman encoded) that will be accepted. See sections 31 // 5.1 and 5.2 of RFC 7541. This is a defense against OOM attacks; HTTP/2 32 // allows a decoder to enforce any limit of the size of the header lists 33 // that it is willing decode, including less than the MAX_HEADER_LIST_SIZE 34 // setting, a setting that is initially unlimited. For example, we might 35 // choose to send a MAX_HEADER_LIST_SIZE of 64KB, and to use that same value 36 // as the upper bound for individual strings. 37 HpackWholeEntryBuffer(HpackWholeEntryListener* listener, 38 size_t max_string_size); 39 ~HpackWholeEntryBuffer() override; 40 41 HpackWholeEntryBuffer(const HpackWholeEntryBuffer&) = delete; 42 HpackWholeEntryBuffer& operator=(const HpackWholeEntryBuffer&) = delete; 43 44 // Set the listener to be notified when a whole entry has been decoded. 45 // The listener may be changed at any time. 46 void set_listener(HpackWholeEntryListener* listener); 47 48 // Set how much encoded data this decoder is willing to buffer. 49 // TODO(jamessynge): Come up with consistent semantics for this protection 50 // across the various decoders; e.g. should it be for a single string or 51 // a single header entry? 52 void set_max_string_size_bytes(size_t max_string_size_bytes); 53 54 // Ensure that decoded strings pointed to by the HpackDecoderStringBuffer 55 // instances name_ and value_ are buffered, which allows any underlying 56 // transport buffer to be freed or reused without overwriting the decoded 57 // strings. This is needed only when an HPACK entry is split across transport 58 // buffers. See HpackDecoder::DecodeFragment. 59 void BufferStringsIfUnbuffered(); 60 61 // Was an error detected? After an error has been detected and reported, 62 // no further callbacks will be made to the listener. error_detected()63 bool error_detected() const { return error_detected_; } 64 65 // Implement the HpackEntryDecoderListener methods. 66 67 void OnIndexedHeader(size_t index) override; 68 void OnStartLiteralHeader(HpackEntryType entry_type, 69 size_t maybe_name_index) override; 70 void OnNameStart(bool huffman_encoded, size_t len) override; 71 void OnNameData(const char* data, size_t len) override; 72 void OnNameEnd() override; 73 void OnValueStart(bool huffman_encoded, size_t len) override; 74 void OnValueData(const char* data, size_t len) override; 75 void OnValueEnd() override; 76 void OnDynamicTableSizeUpdate(size_t size) override; 77 78 private: 79 void ReportError(HpackDecodingError error); 80 81 HpackWholeEntryListener* listener_; 82 HpackDecoderStringBuffer name_, value_; 83 84 // max_string_size_bytes_ specifies the maximum allowed size of an on-the-wire 85 // string. Larger strings will be reported as errors to the listener; the 86 // endpoint should treat these as COMPRESSION errors, which are CONNECTION 87 // level errors. 88 size_t max_string_size_bytes_; 89 90 // The name index (or zero) of the current header entry with a literal value. 91 size_t maybe_name_index_; 92 93 // The type of the current header entry (with literals) that is being decoded. 94 HpackEntryType entry_type_; 95 96 bool error_detected_ = false; 97 }; 98 99 } // namespace http2 100 101 #endif // QUICHE_HTTP2_HPACK_DECODER_HPACK_WHOLE_ENTRY_BUFFER_H_ 102