mcs/class/corlib/System.Security.Cryptography/CryptoStream.cs

   1 //
   2 // System.Security.Cryptography CryptoStream.cs
   3 //
   4 // Authors:
   5 //      Thomas Neidhart (tome@sbox.tugraz.at)
   6 //      Sebastien Pouliot (sebastien@ximian.com)
   7 //
   8 // Portions (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
   9 // (C) 2004 Novell (http://www.novell.com)
  10 //
  11
  12 //
  13 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  14 //
  15 // Permission is hereby granted, free of charge, to any person obtaining
  16 // a copy of this software and associated documentation files (the
  17 // "Software"), to deal in the Software without restriction, including
  18 // without limitation the rights to use, copy, modify, merge, publish,
  19 // distribute, sublicense, and/or sell copies of the Software, and to
  20 // permit persons to whom the Software is furnished to do so, subject to
  21 // the following conditions:
  22 //
  23 // The above copyright notice and this permission notice shall be
  24 // included in all copies or substantial portions of the Software.
  25 //
  26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  33 //
  34
  35 using System;
  36 using System.Globalization;
  37 using System.IO;
  38 using System.Runtime.InteropServices;
  39
  40 namespace System.Security.Cryptography {
  41
  42         public class CryptoStream : Stream {
  43                 private Stream _stream;
  44                 private ICryptoTransform _transform;
  45                 private CryptoStreamMode _mode;
  46                 private byte[] _currentBlock;
  47                 private bool _disposed;
  48                 private bool _flushedFinalBlock;
  49                 private int _partialCount;
  50                 private bool _endOfStream;
  51
  52                 private byte[] _waitingBlock;
  53                 private int _waitingCount;
  54
  55                 private byte[] _transformedBlock;
  56                 private int _transformedPos;
  57                 private int _transformedCount;
  58
  59                 private byte[] _workingBlock;
  60                 private int _workingCount;
  61
  62                 public CryptoStream (Stream stream, ICryptoTransform transform, CryptoStreamMode mode)
  63                 {
  64                         if ((mode == CryptoStreamMode.Read) && (!stream.CanRead)) {
  65                                 throw new ArgumentException (
  66                                         Locale.GetText ("Can't read on stream"));
  67                         }
  68                         if ((mode == CryptoStreamMode.Write) && (!stream.CanWrite)) {
  69                                 throw new ArgumentException (
  70                                         Locale.GetText ("Can't write on stream"));
  71                         }
  72                         _stream = stream;
  73                         _transform = transform;
  74                         _mode = mode;
  75                         _disposed = false;
  76                         if (transform != null) {
  77                                 _workingBlock = new byte [transform.InputBlockSize];
  78                                 if (mode == CryptoStreamMode.Read)
  79                                         _currentBlock = new byte [transform.InputBlockSize];
  80                                 else if (mode == CryptoStreamMode.Write)
  81                                         _currentBlock = new byte [transform.OutputBlockSize];
  82                         }
  83                 }
  84
  85                 ~CryptoStream ()
  86                 {
  87                         Dispose (false);
  88                 }
  89
  90                 public override bool CanRead {
  91                         get { return (_mode == CryptoStreamMode.Read); }
  92                 }
  93
  94                 public override bool CanSeek {
  95                         get { return false; }
  96                 }
  97
  98                 public override bool CanWrite {
  99                         get { return (_mode == CryptoStreamMode.Write); }
 100                 }
 101
 102                 public override long Length {
 103                         get { throw new NotSupportedException ("Length"); }
 104                 }
 105
 106                 public override long Position {
 107                         get { throw new NotSupportedException ("Position"); }
 108                         set { throw new NotSupportedException ("Position"); }
 109                 }
 110
 111                 public void Clear ()
 112                 {
 113                         Dispose (true);
 114                         GC.SuppressFinalize (this); // not called in Stream.Dispose
 115                 }
 116
 117                 // LAMESPEC: A CryptoStream can be close in read mode
 118                 public override void Close ()
 119                 {
 120                         // only flush in write mode (bugzilla 46143)
 121                         if ((!_flushedFinalBlock) && (_mode == CryptoStreamMode.Write))
 122                                 FlushFinalBlock ();
 123
 124                         if (_stream != null)
 125                                 _stream.Close ();
 126                 }
 127
 128                 public override int Read ([In,Out] byte[] buffer, int offset, int count)
 129                 {
 130                         if (_mode != CryptoStreamMode.Read) {
 131                                 throw new NotSupportedException (
 132                                         Locale.GetText ("not in Read mode"));
 133                         }
 134                         if (offset < 0) {
 135                                 throw new ArgumentOutOfRangeException ("offset",
 136                                         Locale.GetText ("negative"));
 137                         }
 138                         if (count < 0) {
 139                                 throw new ArgumentOutOfRangeException ("count",
 140                                         Locale.GetText ("negative"));
 141                         }
 142                         // yes - buffer.Length will throw a NullReferenceException if buffer is null
 143                         // but by doing so we match MS implementation
 144                         // re-ordered to avoid integer overflow
 145                         if (offset > buffer.Length - count) {
 146                                 throw new ArgumentException ("(offset+count)",
 147                                         Locale.GetText ("buffer overflow"));
 148                         }
 149                         // for some strange reason ObjectDisposedException isn't throw
 150                         // instead we get a ArgumentNullException (probably from an internal method)
 151                         if (_workingBlock == null) {
 152                                 throw new ArgumentNullException (
 153                                         Locale.GetText ("object _disposed"));
 154                         }
 155
 156                         int result = 0;
 157                         if ((count == 0) || ((_transformedPos == _transformedCount) && (_endOfStream)))
 158                                 return result;
 159
 160                         if (_waitingBlock == null) {
 161                                 _transformedBlock = new byte [_transform.OutputBlockSize << 2];
 162                                 _transformedPos = 0;
 163                                 _transformedCount = 0;
 164                                 _waitingBlock = new byte [_transform.InputBlockSize];
 165                                 _waitingCount = _stream.Read (_waitingBlock, 0, _waitingBlock.Length);
 166                         }
 167
 168                         while (count > 0) {
 169                                 // transformed but not yet returned
 170                                 int length = (_transformedCount - _transformedPos);
 171
 172                                 // need more data - at least one full block must be available if we haven't reach the end of the stream
 173                                 if (length < _transform.InputBlockSize) {
 174                                         int transformed = 0;
 175
 176                                         // load a new block
 177                                         _workingCount = _stream.Read (_workingBlock, 0, _workingBlock.Length);
 178                                         _endOfStream = (_workingCount < _transform.InputBlockSize);
 179
 180                                         if (!_endOfStream) {
 181                                                 // transform the waiting block
 182                                                 transformed = _transform.TransformBlock (_waitingBlock, 0, _waitingBlock.Length, _transformedBlock, _transformedCount);
 183
 184                                                 // transfer temporary to waiting
 185                                                 Buffer.BlockCopy (_workingBlock, 0, _waitingBlock, 0, _workingCount);
 186                                                 _waitingCount = _workingCount;
 187                                         }
 188                                         else {
 189                                                 if (_workingCount > 0) {
 190                                                         // transform the waiting block
 191                                                         transformed = _transform.TransformBlock (_waitingBlock, 0, _waitingBlock.Length, _transformedBlock, _transformedCount);
 192
 193                                                         // transfer temporary to waiting
 194                                                         Buffer.BlockCopy (_workingBlock, 0, _waitingBlock, 0, _workingCount);
 195                                                         _waitingCount = _workingCount;
 196
 197                                                         length += transformed;
 198                                                         _transformedCount += transformed;
 199                                                 }
 200                                                 byte[] input = _transform.TransformFinalBlock (_waitingBlock, 0, _waitingCount);
 201                                                 transformed = input.Length;
 202                                                 Buffer.BlockCopy (input, 0, _transformedBlock, _transformedCount, input.Length);
 203                                                 // zeroize this last block
 204                                                 Array.Clear (input, 0, input.Length);
 205                                         }
 206
 207                                         length += transformed;
 208                                         _transformedCount += transformed;
 209                                 }
 210                                 // compaction
 211                                 if (_transformedPos > _transform.InputBlockSize) {
 212                                         Buffer.BlockCopy (_transformedBlock, _transformedPos, _transformedBlock, 0, length);
 213                                         _transformedCount -= _transformedPos;
 214                                         _transformedPos = 0;
 215                                 }
 216
 217                                 length = ((count < length) ? count : length);
 218                                 if (length > 0) {
 219                                         Buffer.BlockCopy (_transformedBlock, _transformedPos, buffer, offset, length);
 220                                         _transformedPos += length;
 221
 222                                         result += length;
 223                                         offset += length;
 224                                         count -= length;
 225                                 }
 226
 227                                 // there may not be enough data in the stream for a
 228                                 // complete block
 229                                 if (((length != _transform.InputBlockSize) && (_waitingCount != _transform.InputBlockSize)) || (_endOfStream)) {
 230                                         count = 0;      // no more data can be read
 231                                 }
 232                         }
 233
 234                         return result;
 235                 }
 236
 237                 public override void Write (byte[] buffer, int offset, int count)
 238                 {
 239                         if (_mode != CryptoStreamMode.Write) {
 240                                 throw new NotSupportedException (
 241                                         Locale.GetText ("not in Write mode"));
 242                         }
 243                         if (offset < 0) {
 244                                 throw new ArgumentOutOfRangeException ("offset",
 245                                         Locale.GetText ("negative"));
 246                         }
 247                         if (count < 0) {
 248                                 throw new ArgumentOutOfRangeException ("count",
 249                                         Locale.GetText ("negative"));
 250                         }
 251                         // re-ordered to avoid integer overflow
 252                         if (offset > buffer.Length - count) {
 253                                 throw new ArgumentException ("(offset+count)",
 254                                         Locale.GetText ("buffer overflow"));
 255                         }
 256
 257                         // partial block (in progress)
 258                         if ((_partialCount > 0) && (_partialCount != _transform.InputBlockSize)) {
 259                                 int remainder = _transform.InputBlockSize - _partialCount;
 260                                 remainder = ((count < remainder) ? count : remainder);
 261                                 Buffer.BlockCopy (buffer, offset, _workingBlock, _partialCount, remainder);
 262                                 _partialCount += remainder;
 263                                 offset += remainder;
 264                                 count -= remainder;
 265                         }
 266
 267                         int bufferPos = offset;
 268                         while (count > 0) {
 269                                 if (_partialCount == _transform.InputBlockSize) {
 270                                         // use partial block to avoid (re)allocation
 271                                         int len = _transform.TransformBlock (_workingBlock, 0, _partialCount, _currentBlock, 0);
 272                                         _stream.Write (_currentBlock, 0, len);
 273                                         // reset
 274                                         _partialCount = 0;
 275                                 }
 276
 277                                 if (_transform.CanTransformMultipleBlocks) {
 278                                         // transform all except the last block (which may be the last block
 279                                         // of the stream and require TransformFinalBlock)
 280                                         int numBlock = ((_partialCount + count) / _transform.InputBlockSize);
 281                                         int multiSize = (numBlock * _transform.InputBlockSize);
 282                                         if (numBlock > 0) {
 283                                                 byte[] multiBlocks = new byte [multiSize];
 284                                                 int len = _transform.TransformBlock (buffer, offset, multiSize, multiBlocks, 0);
 285                                                 _stream.Write (multiBlocks, 0, len);
 286                                                 // copy last block into _currentBlock
 287                                                 _partialCount = count - multiSize;
 288                                                 Buffer.BlockCopy (buffer, offset + multiSize, _workingBlock, 0, _partialCount);
 289                                         }
 290                                         else {
 291                                                 Buffer.BlockCopy (buffer, offset, _workingBlock, _partialCount, count);
 292                                                 _partialCount += count;
 293                                         }
 294                                         count = 0; // the last block, if any, is in _workingBlock
 295                                 }
 296                                 else {
 297                                         int len = Math.Min (_transform.InputBlockSize - _partialCount, count);
 298                                         Buffer.BlockCopy (buffer, bufferPos, _workingBlock, _partialCount, len);
 299                                         bufferPos += len;
 300                                         _partialCount += len;
 301                                         count -= len;
 302                                         // here block may be full, but we wont TransformBlock it until next iteration
 303                                         // so that the last block will be called in FlushFinalBlock using TransformFinalBlock
 304                                 }
 305                         }
 306                 }
 307
 308                 public override void Flush ()
 309                 {
 310                         if (_stream != null)
 311                                 _stream.Flush ();
 312                 }
 313
 314                 public void FlushFinalBlock ()
 315                 {
 316                         if (_flushedFinalBlock) {
 317                                 throw new NotSupportedException (
 318                                         Locale.GetText ("This method cannot be called twice."));
 319                         }
 320                         if (_mode != CryptoStreamMode.Write) {
 321                                 throw new NotSupportedException (
 322                                         Locale.GetText ("cannot flush a non-writeable CryptoStream"));
 323                         }
 324
 325                         _flushedFinalBlock = true;
 326                         byte[] finalBuffer = _transform.TransformFinalBlock (_workingBlock, 0, _partialCount);
 327                         if (_stream != null) {
 328                                 _stream.Write (finalBuffer, 0, finalBuffer.Length);
 329                                 if (_stream is CryptoStream) {
 330                                         // for cascading crypto streams
 331                                         (_stream as CryptoStream).FlushFinalBlock ();
 332                                 }
 333                                 _stream.Flush ();
 334                         }
 335                         // zeroize
 336                         Array.Clear (finalBuffer, 0, finalBuffer.Length);
 337                 }
 338
 339                 public override long Seek (long offset, SeekOrigin origin)
 340                 {
 341                         throw new NotSupportedException ("Seek");
 342                 }
 343
 344                 // LAMESPEC: Exception NotSupportedException not documented
 345                 public override void SetLength (long value)
 346                 {
 347                         throw new NotSupportedException ("SetLength");
 348                 }
 349
 350                 protected virtual void Dispose (bool disposing)
 351                 {
 352                         if (!_disposed) {
 353                                 _disposed = true;
 354                                 // always cleared for security reason
 355                                 if (_workingBlock != null)
 356                                         Array.Clear (_workingBlock, 0, _workingBlock.Length);
 357                                 if (_currentBlock != null)
 358                                         Array.Clear (_currentBlock, 0, _currentBlock.Length);
 359                                 if (disposing) {
 360                                         _stream = null;
 361                                         _workingBlock = null;
 362                                         _currentBlock = null;
 363                                 }
 364                         }
 365                 }
 366         }
 367 }