Add U2F request state machines

device/u2f/u2f_request.cc

+// Copyright 2017 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 "u2f_request.h"
+
+#include "base/bind.h"
+#include "base/memory/ptr_util.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "device/base/device_client.h"
+#include "u2f_hid_device.h"
+
+namespace device {
+
+U2fRequest::U2fRequest(const ResponseCallback& cb)
+    : state_(State::INIT),
+      cb_(cb),
+      hid_service_observer_(this),
+      weak_factory_(this) {
+  filter_.SetUsagePage(0xf1d0);
+}
+
+void U2fRequest::Transition() {
+  switch (state_) {
+    case State::IDLE:
+      IterateDevice();
+      if (!current_device_) {
+        // No devices available
+        state_ = State::OFF;
+        break;
+      }
+      state_ = State::WINK;
+      current_device_->TryWink(
+          base::Bind(&U2fRequest::Transition, weak_factory_.GetWeakPtr()));
+      break;
+    case State::WINK:
+      state_ = State::BUSY;
+      TryDevice();
+    default:
+      break;
+  }
+}
+
+void U2fRequest::Start() {
+  if (state_ == State::INIT) {
+    state_ = State::BUSY;
+    Enumerate();
+  }
+}
+
+void U2fRequest::Enumerate() {
+  HidService* hid_service = DeviceClient::Get()->GetHidService();
+  DCHECK(hid_service);
+  hid_service_observer_.Add(hid_service);
+  hid_service->GetDevices(
+      base::Bind(&U2fRequest::OnEnumerate, weak_factory_.GetWeakPtr()));
+}
+
+void U2fRequest::OnEnumerate(
+    const std::vector<scoped_refptr<HidDeviceInfo>>& devices) {
+  for (auto device_info : devices) {
+    if (filter_.Matches(device_info))
+      devices_.push_back(base::MakeUnique<U2fHidDevice>(device_info));
+  }
+
+  state_ = State::IDLE;
+  Transition();
+}
+
+void U2fRequest::OnDeviceAdded(scoped_refptr<HidDeviceInfo> device_info) {
+  // Ignore non-U2F devices
+  if (!filter_.Matches(device_info))
+    return;
+
+  auto device = base::MakeUnique<U2fHidDevice>(device_info);
+  devices_.push_back(std::move(device));
+
+  // Start the state machine if this is the only device
+  if (state_ == State::OFF) {
+    state_ = State::IDLE;
+    delay_callback_.Cancel();
+    Transition();
+  }
+}
+
+void U2fRequest::OnDeviceRemoved(scoped_refptr<HidDeviceInfo> device_info) {
+  // Ignore non-U2F devices
+  if (!filter_.Matches(device_info))
+    return;
+
+  auto device = base::MakeUnique<U2fHidDevice>(device_info);
+
+  // Check if the active device was removed
+  if (current_device_ && current_device_->GetId() == device->GetId()) {
+    current_device_ = nullptr;
+    state_ = State::IDLE;
+    Transition();
+    return;
+  }
+
+  // Remove the device if it exists in the devices list
+  for (auto it = devices_.begin(); it != devices_.end();) {
+    if ((*it)->GetId() == device->GetId()) {
+      it = devices_.erase(it);
+      return;
+    } else {
+      ++it;
+    }
+  }
+
+  // Remove the device if it exists in the attempted devices list
+  for (auto it = attempted_devices_.begin(); it != attempted_devices_.end();) {
+    if ((*it)->GetId() == device->GetId()) {
+      it = attempted_devices_.erase(it);
+      return;
+    } else {
+      ++it;
+    }
+  }
+}
+
+void U2fRequest::IterateDevice() {
+  // Move active device to attempted device list
+  if (current_device_)
+    attempted_devices_.push_back(std::move(current_device_));
+
+  // If there is an additional device on device list, make it active.
+  // Otherwise, if all devices have been tried, move attempted devices back to
+  // the main device list.
+  if (devices_.size() > 0) {
+    current_device_ = std::move(devices_.front());
+    devices_.pop_front();
+  } else if (attempted_devices_.size() > 0) {
+    devices_ = std::move(attempted_devices_);
+    // After trying every device, wait 200ms before trying again
+    delay_callback_.Reset(
+        base::Bind(&U2fRequest::OnWaitComplete, weak_factory_.GetWeakPtr()));
+    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+        FROM_HERE, delay_callback_.callback(),
+        base::TimeDelta::FromMilliseconds(200));
+  }
+}
+
+void U2fRequest::OnWaitComplete() {
+  state_ = State::IDLE;
+  Transition();
+}
+
+void U2fRequest::AddDeviceForTesting(std::unique_ptr<U2fDevice> device) {
+  devices_.push_back(std::move(device));
+
+  // Start the state machine if this is the only device
+  if (state_ == State::OFF) {
+    state_ = State::IDLE;
+    delay_callback_.Cancel();
+    Transition();
+  }

[Reilly Grant (use Gerrit), 2017/04/21 20:10:01]

I recommend pulling this out into an AddDevice() function that can be called
here and from OnDeviceAdded() so that this logic doesn't get out sync.

[Casey Piper, 2017/04/21 22:55:16]

Done.

+}
+
+U2fRequest::~U2fRequest() {}
+
+}  // namespace device