Add QuicFramer and friends.

net/quic/quic_data_writer.cc

+// Copyright (c) 2012 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 "net/quic/quic_data_writer.h"
+
+#include <algorithm>
+#include <limits>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "net/quic/quic_protocol.h"
+
+using std::numeric_limits;
+
+namespace net {
+
+QuicDataWriter::QuicDataWriter(size_t size)
+    : buffer_(new char[size]),

[jar (doing other things), 2012/10/14 23:04:38]

nit/comment: It is a bit tempting to have a fixed size character array that can
hold a UDP packet, if this is really meant to be the interior of a packet.  We'd
avoid secondary allocations,.. realloc, etc.

[Ryan Hamilton, 2012/10/15 21:22:08]

But then the take() method could not be implemented.

+      capacity_(size),
+      length_(0) {
+}
+
+QuicDataWriter::~QuicDataWriter() {
+  delete[] buffer_;
+}
+
+char* QuicDataWriter::BeginWrite(size_t length) {
+  size_t offset = length_;
+  size_t needed_size = length_ + length;
+  if (needed_size > capacity_) {

[jar (doing other things), 2012/10/14 23:04:38]

nit: to handle wrapping, perhaps better would be:

if (capacity_ - length_ < length)
  return NULL;

[Ryan Hamilton, 2012/10/15 21:22:08]

Done.  FYI, This code was simply copied from the spdy variant.

+    return NULL;
+  }
+
+#ifdef ARCH_CPU_64_BITS
+  DCHECK_LE(length, numeric_limits<uint32>::max());
+#endif
+
+  return buffer_ + offset;

[jar (doing other things), 2012/10/14 23:04:38]

Why did you save length_ into offset?  Isn't this just
return buffer_ + length_;

[Ryan Hamilton, 2012/10/15 21:22:08]

This code was copied from the spdy variant.

+}
+
+bool QuicDataWriter::AdvancePointer(uint32 len) {
+  if (!BeginWrite(len)) return false;

[jar (doing other things), 2012/10/14 23:04:38]

nit: probably want to be consistent with braces and newline.

[Ryan Hamilton, 2012/10/15 21:22:08]

Done.  But just to be clear, this is perfectly acceptable style as is.

+  length_ += len;
+  return true;
+}
+
+bool QuicDataWriter::WriteBytes(const void* data, uint32 data_len) {
+  char* dest = BeginWrite(data_len);
+  if (!dest) {
+    return false;
+  }
+
+  memcpy(dest, data, data_len);
+
+  length_ += data_len;
+  return true;
+}
+
+void QuicDataWriter::WriteUint64ToBuffer(uint64 value, char* buffer) {
+  memcpy(buffer, &value, sizeof(value));
+}
+
+void QuicDataWriter::WriteUint128ToBuffer(uint128 value, char* buffer) {
+  WriteUint64ToBuffer(value.lo, buffer);
+  WriteUint64ToBuffer(value.hi, buffer + sizeof(value.lo));
+}
+
+}  // namespace net