dom/quota/EncryptingOutputStream.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_quota_EncryptingOutputStream_h
   8 #define mozilla_dom_quota_EncryptingOutputStream_h
   9
  10 // Local includes
  11 #include "EncryptedBlock.h"  // for EncryptedBlock
  12
  13 // Global includes
  14 #include <cstddef>
  15 #include <cstdint>
  16 #include "ErrorList.h"
  17 #include "mozilla/InitializedOnce.h"
  18 #include "mozilla/Maybe.h"
  19 #include "mozilla/NotNull.h"
  20 #include "nsCOMPtr.h"
  21 #include "nsIOutputStream.h"
  22 #include "nsISupports.h"
  23 #include "nsTArray.h"
  24 #include "nscore.h"
  25
  26 class nsIInputStream;
  27 class nsIRandomGenerator;
  28
  29 namespace mozilla::dom::quota {
  30 class EncryptingOutputStreamBase : public nsIOutputStream {
  31  public:
  32   NS_DECL_THREADSAFE_ISUPPORTS
  33
  34   NS_IMETHOD Write(const char* aBuf, uint32_t aCount, uint32_t* _retval) final;
  35   NS_IMETHOD WriteFrom(nsIInputStream* aFromStream, uint32_t aCount,
  36                        uint32_t* _retval) final;
  37   NS_IMETHOD IsNonBlocking(bool* _retval) final;
  38
  39  protected:
  40   EncryptingOutputStreamBase(nsCOMPtr<nsIOutputStream> aBaseStream,
  41                              size_t aBlockSize);
  42
  43   virtual ~EncryptingOutputStreamBase() = default;
  44
  45   nsresult WriteAll(const char* aBuf, uint32_t aCount,
  46                     uint32_t* aBytesWrittenOut);
  47
  48   InitializedOnce<const NotNull<nsCOMPtr<nsIOutputStream>>> mBaseStream;
  49   const size_t mBlockSize;
  50 };
  51
  52 // Wraps another nsIOutputStream using the CipherStrategy to encrypt it a
  53 // page-based manner. Essentially, the CipherStrategy is not actually
  54 // necessarily doing encryption, but any transformation to a page requiring some
  55 // fixed-size reserved size per page.
  56 //
  57 // Paired with DecryptingInputStream which can be used to read the data written
  58 // to the underlying stream, using the same (or more generally, a compatible)
  59 // CipherStrategy, when created with the same key (assuming a symmetric cipher
  60 // is being used; in principle, an asymmetric cipher would probably also work).
  61 template <typename CipherStrategy>
  62 class EncryptingOutputStream final : public EncryptingOutputStreamBase {
  63  public:
  64   // Construct a new blocking output stream to encrypt data to
  65   // the given base stream.  The base stream must also be blocking.
  66   // The encryption block size may optionally be set to a value
  67   // up to kMaxBlockSize.
  68   explicit EncryptingOutputStream(nsCOMPtr<nsIOutputStream> aBaseStream,
  69                                   size_t aBlockSize,
  70                                   typename CipherStrategy::KeyType aKey);
  71
  72  private:
  73   ~EncryptingOutputStream();
  74
  75   nsresult FlushToBaseStream();
  76
  77   bool EnsureBuffers();
  78
  79   CipherStrategy mCipherStrategy;
  80
  81   // Buffer holding copied plain data.  This must be copied here
  82   // so that the encryption can be performed on a single flat buffer.
  83   // XXX This is only necessary if the data written doesn't contain a portion of
  84   // effective block size at a block boundary.
  85   nsTArray<uint8_t> mBuffer;
  86
  87   nsCOMPtr<nsIRandomGenerator> mRandomGenerator;
  88
  89   // The next byte in the plain data to copy incoming data to.
  90   size_t mNextByte = 0;
  91
  92   // Buffer holding the resulting encrypted data.
  93   using EncryptedBlockType = EncryptedBlock<CipherStrategy::BlockPrefixLength,
  94                                             CipherStrategy::BasicBlockSize>;
  95   Maybe<EncryptedBlockType> mEncryptedBlock;
  96
  97  public:
  98   NS_IMETHOD Close() override;
  99   NS_IMETHOD Flush() override;
 100   NS_IMETHOD StreamStatus() override;
 101   NS_IMETHOD WriteSegments(nsReadSegmentFun aReader, void* aClosure,
 102                            uint32_t aCount, uint32_t* _retval) override;
 103 };
 104
 105 }  // namespace mozilla::dom::quota
 106
 107 #endif