CryptoBuffer.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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/. */

#include "CryptoBuffer.h"
#include "secitem.h"
#include "mozilla/Base64.h"
#include "mozilla/dom/UnionTypes.h"

namespace mozilla {
namespace dom {

uint8_t*
CryptoBuffer::Assign(const CryptoBuffer& aData)
{
  // Same as in nsTArray_Impl::operator=, but return the value
  // returned from ReplaceElementsAt to enable OOM detection
  return ReplaceElementsAt(0, Length(), aData.Elements(), aData.Length());
}

uint8_t*
CryptoBuffer::Assign(const uint8_t* aData, uint32_t aLength)
{
  return ReplaceElementsAt(0, Length(), aData, aLength);
}

uint8_t*
CryptoBuffer::Assign(const SECItem* aItem)
{
  MOZ_ASSERT(aItem);
  return Assign(aItem->data, aItem->len);
}

uint8_t*
CryptoBuffer::Assign(const ArrayBuffer& aData)
{
  aData.ComputeLengthAndData();
  return Assign(aData.Data(), aData.Length());
}

uint8_t*
CryptoBuffer::Assign(const ArrayBufferView& aData)
{
  aData.ComputeLengthAndData();
  return Assign(aData.Data(), aData.Length());
}

uint8_t*
CryptoBuffer::Assign(const ArrayBufferViewOrArrayBuffer& aData)
{
  if (aData.IsArrayBufferView()) {
    return Assign(aData.GetAsArrayBufferView());
  } else if (aData.IsArrayBuffer()) {
    return Assign(aData.GetAsArrayBuffer());
  }

  // If your union is uninitialized, something's wrong
  MOZ_ASSERT(false);
  SetLength(0);
  return nullptr;
}

uint8_t*
CryptoBuffer::Assign(const OwningArrayBufferViewOrArrayBuffer& aData)
{
  if (aData.IsArrayBufferView()) {
    return Assign(aData.GetAsArrayBufferView());
  } else if (aData.IsArrayBuffer()) {
    return Assign(aData.GetAsArrayBuffer());
  }

  // If your union is uninitialized, something's wrong
  MOZ_ASSERT(false);
  SetLength(0);
  return nullptr;
}

// Helpers to encode/decode JWK's special flavor of Base64
// * No whitespace
// * No padding
// * URL-safe character set
nsresult
CryptoBuffer::FromJwkBase64(const nsString& aBase64)
{
  NS_ConvertUTF16toUTF8 temp(aBase64);
  temp.StripWhitespace();

  // Re-add padding
  if (temp.Length() % 4 == 3) {
    temp.AppendLiteral("=");
  } else if (temp.Length() % 4 == 2) {
    temp.AppendLiteral("==");
  } if (temp.Length() % 4 == 1) {
    return NS_ERROR_FAILURE; // bad Base64
  }

  // Translate from URL-safe character set to normal
  temp.ReplaceChar('-', '+');
  temp.ReplaceChar('_', '/');

  // Perform the actual base64 decode
  nsCString binaryData;
  nsresult rv = Base64Decode(temp, binaryData);
  NS_ENSURE_SUCCESS(rv, rv);

  if (!Assign((const uint8_t*) binaryData.BeginReading(),
              binaryData.Length())) {
    return NS_ERROR_FAILURE;
  }

  return NS_OK;
}

nsresult
CryptoBuffer::ToJwkBase64(nsString& aBase64)
{
  // Shortcut for the empty octet string
  if (Length() == 0) {
    aBase64.Truncate();
    return NS_OK;
  }

  // Perform the actual base64 encode
  nsCString base64;
  nsDependentCSubstring binaryData((const char*) Elements(),
                                   (const char*) (Elements() + Length()));
  nsresult rv = Base64Encode(binaryData, base64);
  NS_ENSURE_SUCCESS(rv, rv);

  // Strip padding
  base64.Trim("=");

  // Translate to the URL-safe charset
  base64.ReplaceChar('+', '-');
  base64.ReplaceChar('/', '_');
  if (base64.FindCharInSet("+/", 0) != kNotFound) {
    return NS_ERROR_FAILURE;
  }

  CopyASCIItoUTF16(base64, aBase64);
  return NS_OK;
}

bool
CryptoBuffer::ToSECItem(PLArenaPool *aArena, SECItem* aItem) const
{
  aItem->type = siBuffer;
  aItem->data = nullptr;

  if (!::SECITEM_AllocItem(aArena, aItem, Length())) {
    return false;
  }

  memcpy(aItem->data, Elements(), Length());
  return true;
}

JSObject*
CryptoBuffer::ToUint8Array(JSContext* aCx) const
{
  return Uint8Array::Create(aCx, Length(), Elements());
}


// "BigInt" comes from the WebCrypto spec
// ("unsigned long" isn't very "big", of course)
// Likewise, the spec calls for big-endian ints
bool
CryptoBuffer::GetBigIntValue(unsigned long& aRetVal)
{
  if (Length() > sizeof(aRetVal)) {
    return false;
  }

  aRetVal = 0;
  for (size_t i=0; i < Length(); ++i) {
    aRetVal = (aRetVal << 8) + ElementAt(i);
  }
  return true;
}

} // namespace dom
} // namespace mozilla