--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancFramework/Sources/HttpServer/HttpStreamTranscoder.cpp	Wed Jun 10 20:30:34 2020 +0200
@@ -0,0 +1,251 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2020 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * In addition, as a special exception, the copyright holders of this
+ * program give permission to link the code of its release with the
+ * OpenSSL project's "OpenSSL" library (or with modified versions of it
+ * that use the same license as the "OpenSSL" library), and distribute
+ * the linked executables. You must obey the GNU General Public License
+ * in all respects for all of the code used other than "OpenSSL". If you
+ * modify file(s) with this exception, you may extend this exception to
+ * your version of the file(s), but you are not obligated to do so. If
+ * you do not wish to do so, delete this exception statement from your
+ * version. If you delete this exception statement from all source files
+ * in the program, then also delete it here.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "../PrecompiledHeaders.h"
+#include "HttpStreamTranscoder.h"
+
+#include "../OrthancException.h"
+#include "../Compression/ZlibCompressor.h"
+
+#include <string.h>   // For memcpy()
+#include <cassert>
+
+#include <stdio.h>
+
+namespace Orthanc
+{
+  void HttpStreamTranscoder::ReadSource(std::string& buffer)
+  {
+    if (source_.SetupHttpCompression(false, false) != HttpCompression_None)
+    {
+      throw OrthancException(ErrorCode_InternalError);
+    }
+    
+    uint64_t size = source_.GetContentLength();
+    if (static_cast<uint64_t>(static_cast<size_t>(size)) != size)
+    {
+      throw OrthancException(ErrorCode_NotEnoughMemory);
+    }
+
+    buffer.resize(static_cast<size_t>(size));
+    size_t offset = 0;
+
+    while (source_.ReadNextChunk())
+    {
+      size_t chunkSize = static_cast<size_t>(source_.GetChunkSize());
+      memcpy(&buffer[offset], source_.GetChunkContent(), chunkSize);
+      offset += chunkSize;
+    }
+
+    if (offset != size)
+    {
+      throw OrthancException(ErrorCode_InternalError);
+    }
+  }
+
+
+  HttpCompression HttpStreamTranscoder::SetupZlibCompression(bool deflateAllowed)
+  {
+    uint64_t size = source_.GetContentLength();
+
+    if (size == 0)
+    {
+      return HttpCompression_None;
+    }
+
+    if (size < sizeof(uint64_t))
+    {
+      throw OrthancException(ErrorCode_CorruptedFile);
+    }
+
+    if (deflateAllowed)
+    {
+      bytesToSkip_ = sizeof(uint64_t);
+
+      return HttpCompression_Deflate;
+    }
+    else
+    {
+      // TODO Use stream-based zlib decoding to reduce memory usage
+      std::string compressed;
+      ReadSource(compressed);
+
+      uncompressed_.reset(new BufferHttpSender);
+
+      ZlibCompressor compressor;
+      IBufferCompressor::Uncompress(uncompressed_->GetBuffer(), compressor, compressed);
+
+      return HttpCompression_None;
+    }
+  }
+
+
+  HttpCompression HttpStreamTranscoder::SetupHttpCompression(bool gzipAllowed,
+                                                             bool deflateAllowed)
+  {
+    if (ready_)
+    {
+      throw OrthancException(ErrorCode_BadSequenceOfCalls);
+    }
+
+    ready_ = true;
+
+    switch (sourceCompression_)
+    {
+      case CompressionType_None:
+        return HttpCompression_None;
+
+      case CompressionType_ZlibWithSize:
+        return SetupZlibCompression(deflateAllowed);
+
+      default:
+        throw OrthancException(ErrorCode_NotImplemented);
+    }
+  }
+
+
+  uint64_t HttpStreamTranscoder::GetContentLength()
+  {
+    if (!ready_)
+    {
+      throw OrthancException(ErrorCode_BadSequenceOfCalls);
+    }
+
+    if (uncompressed_.get() != NULL)
+    {
+      return uncompressed_->GetContentLength();
+    }
+    else
+    {
+      uint64_t length = source_.GetContentLength();
+      if (length < bytesToSkip_)
+      {
+        throw OrthancException(ErrorCode_InternalError);
+      }
+
+      return length - bytesToSkip_;
+    }
+  }
+
+
+  bool HttpStreamTranscoder::ReadNextChunk()
+  {
+    if (!ready_)
+    {
+      throw OrthancException(ErrorCode_BadSequenceOfCalls);
+    }
+
+    if (uncompressed_.get() != NULL)
+    {
+      return uncompressed_->ReadNextChunk();
+    }
+
+    assert(skipped_ <= bytesToSkip_);
+    if (skipped_ == bytesToSkip_)
+    {
+      // We have already skipped the first bytes of the stream
+      currentChunkOffset_ = 0;
+      return source_.ReadNextChunk();
+    }
+
+    // This condition can only be true on the first call to "ReadNextChunk()"
+    for (;;)
+    {
+      assert(skipped_ < bytesToSkip_);
+
+      bool ok = source_.ReadNextChunk();
+      if (!ok)
+      {
+        throw OrthancException(ErrorCode_CorruptedFile);
+      }
+
+      size_t remaining = static_cast<size_t>(bytesToSkip_ - skipped_);
+      size_t s = source_.GetChunkSize();
+
+      if (s < remaining)
+      {
+        skipped_ += s;
+      }
+      else if (s == remaining)
+      {
+        // We have skipped enough bytes, but we must read a new chunk
+        currentChunkOffset_ = 0;            
+        skipped_ = bytesToSkip_;
+        return source_.ReadNextChunk();
+      }
+      else
+      {
+        // We have skipped enough bytes, and we have enough data in the current chunk
+        assert(s > remaining);
+        currentChunkOffset_ = remaining;
+        skipped_ = bytesToSkip_;
+        return true;
+      }
+    }
+  }
+
+
+  const char* HttpStreamTranscoder::GetChunkContent()
+  {
+    if (!ready_)
+    {
+      throw OrthancException(ErrorCode_BadSequenceOfCalls);
+    }
+
+    if (uncompressed_.get() != NULL)
+    {
+      return uncompressed_->GetChunkContent();
+    }
+    else
+    {
+      return source_.GetChunkContent() + currentChunkOffset_;
+    }
+  }
+
+  size_t HttpStreamTranscoder::GetChunkSize()
+  {
+    if (!ready_)
+    {
+      throw OrthancException(ErrorCode_BadSequenceOfCalls);
+    }
+
+    if (uncompressed_.get() != NULL)
+    {
+      return uncompressed_->GetChunkSize();
+    }
+    else
+    {
+      return static_cast<size_t>(source_.GetChunkSize() - currentChunkOffset_);
+    }
+  }
+}