Http2Compression.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_net_Http2Compression_Internal_h

#define mozilla_net_Http2Compression_Internal_h

// HPACK - RFC 7541

// https://www.rfc-editor.org/rfc/rfc7541.txt

#include "mozilla/Attributes.h"

#include "nsDeque.h"

#include "nsString.h"

#include "mozilla/Telemetry.h"

#include "mozilla/Mutex.h"

namespace mozilla {

namespace net {

struct HuffmanIncomingTable;

void Http2CompressionCleanup();

class nvPair {

 public:

  nvPair(const nsACString& name, const nsACString& value)

      : mName(name), mValue(value) {}

  uint32_t Size() const { return mName.Length() + mValue.Length() + 32; }

  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const;

  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const;

  nsCString mName;

  nsCString mValue;

};

class nvFIFO {

 public:

  nvFIFO();

  ~nvFIFO();

  void AddElement(const nsCString& name, const nsCString& value);

  void AddElement(const nsCString& name);

  void RemoveElement();

  uint32_t ByteCount() const;

  uint32_t Length() const;

  uint32_t VariableLength() const;

  size_t StaticLength() const;

  void Clear();

  const nvPair* operator[](size_t index) const;

  size_t SizeOfDynamicTable(mozilla::MallocSizeOf aMallocSizeOf) const;

 private:

  uint32_t mByteCount{0};

  nsDeque<nvPair> mTable;

  // This mutex is held when adding or removing elements in the table

  // and when accessing the table from the main thread (in SizeOfDynamicTable)

  // Since the operator[] and other const methods are always called

  // on the socket thread, they don't need to lock the mutex.

  // Mutable so it can be locked in SizeOfDynamicTable which is const

  mutable Mutex mMutex MOZ_UNANNOTATED{"nvFIFO"};

};

class HpackDynamicTableReporter;

class Http2BaseCompressor {

 public:

  Http2BaseCompressor();

  virtual ~Http2BaseCompressor();

  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

  nsresult SetInitialMaxBufferSize(uint32_t maxBufferSize);

  void SetDumpTables(bool dumpTables);

 protected:

  const static uint32_t kDefaultMaxBuffer = 4096;

  virtual void ClearHeaderTable();

  virtual void MakeRoom(uint32_t amount, const char* direction);

  virtual void DumpState(const char*);

  virtual void SetMaxBufferSizeInternal(uint32_t maxBufferSize);

  nsACString* mOutput{nullptr};

  nvFIFO mHeaderTable;

  uint32_t mMaxBuffer{kDefaultMaxBuffer};

  uint32_t mMaxBufferSetting{kDefaultMaxBuffer};

  bool mSetInitialMaxBufferSizeAllowed{true};

  uint32_t mPeakSize{0};

  uint32_t mPeakCount{0};

  MOZ_INIT_OUTSIDE_CTOR

  Telemetry::HistogramID mPeakSizeID;

  MOZ_INIT_OUTSIDE_CTOR

  Telemetry::HistogramID mPeakCountID;

  bool mDumpTables{false};

 private:

  RefPtr<HpackDynamicTableReporter> mDynamicReporter;

};

class Http2Compressor;

class Http2Decompressor final : public Http2BaseCompressor {

 public:

  Http2Decompressor() {

    mPeakSizeID = Telemetry::HPACK_PEAK_SIZE_DECOMPRESSOR;

    mPeakCountID = Telemetry::HPACK_PEAK_COUNT_DECOMPRESSOR;

};

  virtual ~Http2Decompressor() = default;

  // NS_OK: Produces the working set of HTTP/1 formatted headers

  [[nodiscard]] nsresult DecodeHeaderBlock(const uint8_t* data,

                                           uint32_t datalen, nsACString& output,

                                           bool isPush);

  void GetStatus(nsACString& hdr) { hdr = mHeaderStatus; }

  void GetHost(nsACString& hdr) { hdr = mHeaderHost; }

  void GetScheme(nsACString& hdr) { hdr = mHeaderScheme; }

  void GetPath(nsACString& hdr) { hdr = mHeaderPath; }

  void GetMethod(nsACString& hdr) { hdr = mHeaderMethod; }

 private:

  [[nodiscard]] nsresult DoIndexed();

  [[nodiscard]] nsresult DoLiteralWithoutIndex();

  [[nodiscard]] nsresult DoLiteralWithIncremental();

  [[nodiscard]] nsresult DoLiteralInternal(nsACString&, nsACString&, uint32_t);

  [[nodiscard]] nsresult DoLiteralNeverIndexed();

  [[nodiscard]] nsresult DoContextUpdate();

  [[nodiscard]] nsresult DecodeInteger(uint32_t prefixLen, uint32_t& accum);

  [[nodiscard]] nsresult OutputHeader(uint32_t index);

  [[nodiscard]] nsresult OutputHeader(const nsACString& name,

                                      const nsACString& value);

  [[nodiscard]] nsresult CopyHeaderString(uint32_t index, nsACString& name);

  [[nodiscard]] nsresult CopyStringFromInput(uint32_t bytes, nsACString& val);

  uint8_t ExtractByte(uint8_t bitsLeft, uint32_t& bytesConsumed);

  [[nodiscard]] nsresult CopyHuffmanStringFromInput(uint32_t bytes,

                                                    nsACString& val);

  [[nodiscard]] nsresult DecodeHuffmanCharacter(

      const HuffmanIncomingTable* table, uint8_t& c, uint32_t& bytesConsumed,

      uint8_t& bitsLeft);

  [[nodiscard]] nsresult DecodeFinalHuffmanCharacter(

      const HuffmanIncomingTable* table, uint8_t& c, uint8_t& bitsLeft);

  nsCString mHeaderStatus;

  nsCString mHeaderHost;

  nsCString mHeaderScheme;

  nsCString mHeaderPath;

  nsCString mHeaderMethod;

  // state variables when DecodeBlock() is on the stack

  uint32_t mOffset{0};

  const uint8_t* mData{nullptr};

  uint32_t mDataLen{0};

  bool mSeenNonColonHeader{false};

  bool mIsPush{false};

};

class Http2Compressor final : public Http2BaseCompressor {

 public:

  Http2Compressor() {

    mPeakSizeID = Telemetry::HPACK_PEAK_SIZE_COMPRESSOR;

    mPeakCountID = Telemetry::HPACK_PEAK_COUNT_COMPRESSOR;

};

  virtual ~Http2Compressor() = default;

  // HTTP/1 formatted header block as input - HTTP/2 formatted

  // header block as output

  [[nodiscard]] nsresult EncodeHeaderBlock(

      const nsCString& nvInput, const nsACString& method,

      const nsACString& path, const nsACString& host, const nsACString& scheme,

      const nsACString& protocol, bool simpleConnectForm, nsACString& output);

  int64_t GetParsedContentLength() {

    return mParsedContentLength;

  }  // -1 on not found

  void SetMaxBufferSize(uint32_t maxBufferSize);

 private:

  enum outputCode {

    kNeverIndexedLiteral,

    kPlainLiteral,

    kIndexedLiteral,

    kIndex

};

  void DoOutput(Http2Compressor::outputCode code, const class nvPair* pair,

                uint32_t index);

  void EncodeInteger(uint32_t prefixLen, uint32_t val);

  void ProcessHeader(const nvPair inputPair, bool noLocalIndex,

                     bool neverIndex);

  void HuffmanAppend(const nsCString& value);

  void EncodeTableSizeChange(uint32_t newMaxSize);

  int64_t mParsedContentLength{-1};

  bool mBufferSizeChangeWaiting{false};

  uint32_t mLowestBufferSizeWaiting{0};

};

}  // namespace net

}  // namespace mozilla

#endif  // mozilla_net_Http2Compression_Internal_h