Blimp: add packet-level DEFLATE compression using zlib.

blimp/net/compressed_packet_reader.cc

Index: blimp/net/compressed_packet_reader.cc
diff --git a/blimp/net/compressed_packet_reader.cc b/blimp/net/compressed_packet_reader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ac253dc58d8953847a3da4a75147be1e453f2c3f
--- /dev/null
+++ b/blimp/net/compressed_packet_reader.cc
@@ -0,0 +1,96 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "blimp/net/compressed_packet_reader.h"
+
+#include <iostream>
+
+#include "base/callback_helpers.h"
+#include "base/logging.h"
+#include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "base/sys_byteorder.h"
+#include "blimp/net/common.h"
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "net/socket/stream_socket.h"
+
+namespace blimp {
+
+CompressedPacketReader::CompressedPacketReader(scoped_ptr<PacketReader> source)
+    : source_(std::move(source)),
+      compressed_buf_(new net::GrowableIOBuffer),
+      weak_factory_(this) {
+  DCHECK(source_);
+
+  // MAX_WBITS means we are using the maximal window size for decompression;
+  // a negative value means that we are ignoring headers and CRC checks.
+  int init_result = inflateInit2(&zlib_stream_, -MAX_WBITS);
+  DCHECK_EQ(Z_OK, init_result);
+}
+
+CompressedPacketReader::~CompressedPacketReader() {
+  inflateEnd(&zlib_stream_);
+}
+
+void CompressedPacketReader::ReadPacket(
+    const scoped_refptr<net::GrowableIOBuffer>& decompressed_buf,
+    const net::CompletionCallback& callback) {
+  DCHECK(decompressed_buf);
+  DCHECK(!callback.is_null());
+  source_->ReadPacket(
+      compressed_buf_,
+      base::Bind(&CompressedPacketReader::OnCompressedPacketReceived,
+                 weak_factory_.GetWeakPtr(), decompressed_buf, callback));
+}
+
+void CompressedPacketReader::OnCompressedPacketReceived(
+    const scoped_refptr<net::GrowableIOBuffer> decompressed_buf,
+    const net::CompletionCallback& callback,
+    int result) {
+  if (result <= 0) {
+    callback.Run(result);
+    return;
+  }
+
+  callback.Run(DecompressPacket(decompressed_buf, result));
+}
+
+int CompressedPacketReader::DecompressPacket(
+    const scoped_refptr<net::GrowableIOBuffer>& decompressed,
+    int size) {
+  compressed_buf_->set_offset(0);
+  decompressed->set_offset(0);
+  if (static_cast<size_t>(decompressed->capacity()) <
+      kMaxPacketPayloadSizeBytes) {
+    decompressed->SetCapacity(kMaxPacketPayloadSizeBytes);
+  }
+
+  zlib_stream_.next_in = reinterpret_cast<uint8_t*>(compressed_buf_->data());
+  zlib_stream_.avail_in = base::checked_cast<uint32_t>(size);
+  zlib_stream_.next_out = reinterpret_cast<uint8_t*>(decompressed->data());
+  zlib_stream_.avail_out = decompressed->RemainingCapacity();
+  int inflate_result = inflate(&zlib_stream_, Z_SYNC_FLUSH);
+  if (inflate_result != Z_OK) {
+    DLOG(ERROR) << "inflate() returned unexpected error code: "
+                << inflate_result;
+    return net::ERR_UNEXPECTED;
+  }
+  DCHECK_GT(decompressed->RemainingCapacity(),
+            static_cast<int>(zlib_stream_.avail_out));

[Wez, 2016/03/29 23:59:15]

Use a checked cast here, otherwise some crazy scenario could trigger avail_out
to be >2GB and this would trivially pass.

[Kevin M, 2016/03/30 00:26:32]

Done.

+  int decompressed_size =
+      decompressed->RemainingCapacity() - zlib_stream_.avail_out;
+
+  // Verify that the decompressed output isn't bigger than the maximum allowable
+  // payload size, by checking if there are bytes waiting to be processed.
+  if (zlib_stream_.avail_in > 0) {
+    DLOG(ERROR)
+        << "Decompressed buffer size exceeds allowable limits; aborting.";
+    return net::ERR_FILE_TOO_BIG;
+  }
+
+  return decompressed_size;
+}
+
+}  // namespace blimp