Add FIDO U2F message and packet classes

device/u2f/u2f_message.cc

+// Copyright 2016 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 "device/u2f/u2f_message.h"
+#include "device/u2f/u2f_packet.h"
+
+namespace device {
+
+U2fMessage::U2fMessage(const char channel_id[U2fPacket::kChannelIdSize],
+                       const u2f_message_type type,
+                       const std::vector<char> data) {
+  size_t size = data.size();

[Reilly Grant (use Gerrit), 2016/11/23 22:21:50]

Name this remaining_size. I was confused why we were setting this to 0 before
building a packet.

[Casey Piper, 2016/11/29 22:11:15]

Done.

+  char sequence = 0;
+
+  if (size > kMaxMessageSize)
+    return;

[Reilly Grant (use Gerrit), 2016/11/23 22:21:50]

If you're doing validation in the constructor I would define a
U2fMessage::Create() function that returns a new U2fMessage on success and
nullptr on failure.

+
+  std::vector<char> payload;
+  std::vector<char>::const_iterator first = data.begin();
+  std::vector<char>::const_iterator last;
+
+  if (size > kInitPacketDataSize) {
+    last = data.begin() + kInitPacketDataSize;
+    size -= kInitPacketDataSize;
+  } else {
+    last = data.begin() + size;
+    size = 0;
+  }
+
+  payload.insert(std::end(payload), first, last);
+
+  packets_.push_back(scoped_refptr<U2fPacket>(
+      static_cast<U2fPacket*>(new U2fInitPacket(channel_id, type, payload))));

[Reilly Grant (use Gerrit), 2016/11/23 22:21:50]

A static cast is unnecessary here.

[Casey Piper, 2016/11/29 22:11:15]

Acknowledged.

+
+  while (size > 0) {
+    first = last;
+    if (size > kContPacketDataSize) {
+      last = first + kContPacketDataSize;
+      size -= kContPacketDataSize;
+    } else {
+      last = first + size;
+      size = 0;
+    }
+    payload.clear();
+    payload.insert(std::end(payload), first, last);

[Reilly Grant (use Gerrit), 2016/11/23 22:21:50]

I found this reuse of payload confusing. You can just
std::vector<uint8_t>(first, last) to the U2fPacket constructor?

[Casey Piper, 2016/11/29 22:11:15]

Done.

+
+    packets_.push_back(scoped_refptr<U2fPacket>(static_cast<U2fPacket*>(
+        new U2fContPacket(channel_id, sequence, payload))));
+    sequence++;
+  }
+}
+
+U2fMessage::~U2fMessage() {}
+
+scoped_refptr<net::IOBufferWithSize> U2fMessage::GetNextPacket() {
+  if (NumPackets() > 0) {
+    scoped_refptr<net::IOBufferWithSize> buf = packets_.front()->GetBuffer();
+    packets_.pop_front();
+    return buf;
+  }
+  return 0;

[Reilly Grant (use Gerrit), 2016/11/23 22:21:50]

s/0/nullptr/

[Casey Piper, 2016/11/29 22:11:15]

Done.

+}
+
+size_t U2fMessage::NumPackets() {
+  return packets_.size();
+}
+
+}  // namespace device