Add ProtoDecoder for sending messages between Host and Controller when pairing

BUG=380961, 380962

Review URL: https://codereview.chromium.org/448273002

Cr-Commit-Position: refs/heads/master@{#289097}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289097 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 294 insertions, 0 deletions

diff --git a/components/pairing/BUILD.gn b/components/pairing/BUILD.gn
index 55f29ed..d017ec4 100644
--- a/components/pairing/BUILD.gn
+++ b/components/pairing/BUILD.gn
@@ -16,6 +16,8 @@ source_set("pairing") {
     "pairing/host_pairing_controller.h",
     "pairing/message_buffer.cc",
     "pairing/message_buffer.h",
+    "pairing/proto_decoder.cc",
+    "pairing/proto_decoder.h",
   ]
 
   deps = [
diff --git a/components/pairing/proto_decoder.cc b/components/pairing/proto_decoder.cc
new file mode 100644
index 0000000..96b3c24
--- /dev/null
+++ b/components/pairing/proto_decoder.cc
@@ -0,0 +1,201 @@
+// Copyright 2014 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 "components/pairing/proto_decoder.h"
+
+#include "components/pairing/pairing_api.pb.h"
+#include "net/base/io_buffer.h"
+
+namespace {
+enum {
+  MESSAGE_NONE,
+  MESSAGE_HOST_STATUS,
+  MESSAGE_CONFIGURE_HOST,
+  MESSAGE_PAIR_DEVICES,
+  MESSAGE_COMPLETE_SETUP,
+  MESSAGE_ERROR,
+  NUM_MESSAGES,
+};
+}
+
+namespace pairing_chromeos {
+
+ProtoDecoder::ProtoDecoder(Observer* observer)
+    : observer_(observer),
+      next_message_type_(MESSAGE_NONE),
+      next_message_size_(0) {
+  DCHECK(observer_);
+}
+
+ProtoDecoder::~ProtoDecoder() {}
+
+bool ProtoDecoder::DecodeIOBuffer(int size,
+                                  ProtoDecoder::IOBufferRefPtr io_buffer) {
+  // Update the message buffer.
+  message_buffer_.AddIOBuffer(io_buffer, size);
+
+  // If there is no current message, the next byte is the message type.
+  if (next_message_type_ == MESSAGE_NONE) {
+    if (message_buffer_.AvailableBytes() < static_cast<int>(sizeof(uint8_t)))
+      return true;
+
+    uint8_t message_type = MESSAGE_NONE;
+    message_buffer_.ReadBytes(reinterpret_cast<char*>(&message_type),
+                               sizeof(message_type));
+
+    if (message_type == MESSAGE_NONE || message_type >= NUM_MESSAGES) {
+      LOG(ERROR) << "Unknown message type received: " << message_type;
+      return false;
+    }
+    next_message_type_ = message_type;
+  }
+
+  // If the message size isn't set, the next two bytes are the message size.
+  if (next_message_size_ == 0) {
+    if (message_buffer_.AvailableBytes() < static_cast<int>(sizeof(uint16_t)))
+      return true;
+
+    // The size is sent in network byte order.
+    uint8_t high_byte = 0;
+    message_buffer_.ReadBytes(reinterpret_cast<char*>(&high_byte),
+                               sizeof(high_byte));
+    uint8_t low_byte = 0;
+    message_buffer_.ReadBytes(reinterpret_cast<char*>(&low_byte),
+                               sizeof(low_byte));
+
+    next_message_size_ = (high_byte << 8) + low_byte;
+  }
+
+  // If the whole proto buffer is not yet available, return early.
+  if (message_buffer_.AvailableBytes() < next_message_size_)
+    return true;
+
+  std::vector<char> buffer(next_message_size_);
+  message_buffer_.ReadBytes(&buffer[0], next_message_size_);
+
+  switch (next_message_type_) {
+    case MESSAGE_HOST_STATUS: {
+        pairing_api::HostStatus message;
+        message.ParseFromArray(&buffer[0], buffer.size());
+        observer_->OnHostStatusMessage(message);
+      }
+      break;
+    case MESSAGE_CONFIGURE_HOST: {
+        pairing_api::ConfigureHost message;
+        message.ParseFromArray(&buffer[0], buffer.size());
+        observer_->OnConfigureHostMessage(message);
+      }
+      break;
+    case MESSAGE_PAIR_DEVICES: {
+        pairing_api::PairDevices message;
+        message.ParseFromArray(&buffer[0], buffer.size());
+        observer_->OnPairDevicesMessage(message);
+      }
+      break;
+    case MESSAGE_COMPLETE_SETUP: {
+        pairing_api::CompleteSetup message;
+        message.ParseFromArray(&buffer[0], buffer.size());
+        observer_->OnCompleteSetupMessage(message);
+      }
+      break;
+    case MESSAGE_ERROR: {
+        pairing_api::Error message;
+        message.ParseFromArray(&buffer[0], buffer.size());
+        observer_->OnErrorMessage(message);
+      }
+      break;
+
+    default:
+      NOTREACHED();
+      break;
+  }
+
+  // Reset the message data.
+  next_message_type_ = MESSAGE_NONE;
+  next_message_size_ = 0;
+
+  return true;
+}
+
+ProtoDecoder::IOBufferRefPtr ProtoDecoder::SendHostStatus(
+    const pairing_api::HostStatus& message, int* size) {
+  std::string serialized_proto;
+  if (!message.SerializeToString(&serialized_proto)) {
+    NOTREACHED();
+  }
+
+  return SendMessage(MESSAGE_HOST_STATUS, serialized_proto, size);
+}
+
+ProtoDecoder::IOBufferRefPtr ProtoDecoder::SendConfigureHost(
+    const pairing_api::ConfigureHost& message, int* size) {
+  std::string serialized_proto;
+  if (!message.SerializeToString(&serialized_proto)) {
+    NOTREACHED();
+  }
+
+  return SendMessage(MESSAGE_CONFIGURE_HOST, serialized_proto, size);
+}
+
+ProtoDecoder::IOBufferRefPtr ProtoDecoder::SendPairDevices(
+    const pairing_api::PairDevices& message, int* size) {
+  std::string serialized_proto;
+  if (!message.SerializeToString(&serialized_proto)) {
+    NOTREACHED();
+  }
+
+  return SendMessage(MESSAGE_PAIR_DEVICES, serialized_proto, size);
+}
+
+ProtoDecoder::IOBufferRefPtr ProtoDecoder::SendCompleteSetup(
+    const pairing_api::CompleteSetup& message, int* size) {
+  std::string serialized_proto;
+  if (!message.SerializeToString(&serialized_proto)) {
+    NOTREACHED();
+  }
+
+  return SendMessage(MESSAGE_COMPLETE_SETUP, serialized_proto, size);
+}
+
+ProtoDecoder::IOBufferRefPtr ProtoDecoder::SendError(
+    const pairing_api::Error& message, int* size) {
+  std::string serialized_proto;
+  if (!message.SerializeToString(&serialized_proto)) {
+    NOTREACHED();
+  }
+
+  return SendMessage(MESSAGE_ERROR, serialized_proto, size);
+}
+
+ProtoDecoder::IOBufferRefPtr ProtoDecoder::SendMessage(
+    uint8_t message_type,
+    const std::string& message,
+    int* size) {
+  uint16_t message_size = message.size();
+
+  *size = sizeof(message_type) + sizeof(message_size) + message.size();
+  IOBufferRefPtr io_buffer(new net::IOBuffer(*size));
+
+  // Write the message type.
+  int offset = 0;
+  memcpy(&io_buffer->data()[offset], &message_type, sizeof(message_type));
+  offset += sizeof(message_type);
+
+  // Network byte order.
+  // Write the high byte of the size.
+  uint8_t data = (message_size >> 8) & 0xFF;
+  memcpy(&io_buffer->data()[offset], &data, sizeof(data));
+  offset += sizeof(data);
+  // Write the low byte of the size.
+  data = message_size & 0xFF;
+  memcpy(&io_buffer->data()[offset], &data, sizeof(data));
+  offset += sizeof(data);
+
+  // Write the actual message.
+  memcpy(&io_buffer->data()[offset], message.data(), message.size());
+
+  return io_buffer;
+}
+
+}  // namespace pairing_chromeos
diff --git a/components/pairing/proto_decoder.h b/components/pairing/proto_decoder.h
new file mode 100644
index 0000000..e36eb7f
--- /dev/null
+++ b/components/pairing/proto_decoder.h
@@ -0,0 +1,91 @@
+// Copyright 2014 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.
+
+#ifndef COMPONENTS_PAIRING_PROTO_DECODER_H_
+#define COMPONENTS_PAIRING_PROTO_DECODER_H_
+
+#include <deque>
+
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/pairing/message_buffer.h"
+
+namespace net {
+class IOBuffer;
+}
+
+namespace pairing_api {
+class CompleteSetup;
+class ConfigureHost;
+class Error;
+class HostStatus;
+class PairDevices;
+}  // namespace pairing_api
+
+namespace pairing_chromeos {
+
+// A ProtoDecoder collects data from a series of IOBuffers and decodes Proto
+// buffers from the data.  The decoded messages are then forwarded to an
+// observer.
+class ProtoDecoder {
+ public:
+  typedef scoped_refptr<net::IOBuffer> IOBufferRefPtr;
+  class Observer {
+   public:
+    virtual ~Observer() {}
+
+    virtual void OnHostStatusMessage(
+        const pairing_api::HostStatus& message) = 0;
+    virtual void OnConfigureHostMessage(
+        const pairing_api::ConfigureHost& message) = 0;
+    virtual void OnPairDevicesMessage(
+        const pairing_api::PairDevices& message) = 0;
+    virtual void OnCompleteSetupMessage(
+        const pairing_api::CompleteSetup& message) = 0;
+    virtual void OnErrorMessage(
+        const pairing_api::Error& message) = 0;
+
+   protected:
+    Observer() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Observer);
+  };
+
+  explicit ProtoDecoder(Observer* observer);
+  ~ProtoDecoder();
+
+  // Decodes the data from an io_buffer, and sends out events for any complete
+  // messages.
+  bool DecodeIOBuffer(int size, IOBufferRefPtr io_buffer);
+
+  // Convenience functions for serializing messages into an IOBuffer.
+  static IOBufferRefPtr SendHostStatus(const pairing_api::HostStatus& message,
+                                       int* size);
+  static IOBufferRefPtr SendConfigureHost(
+      const pairing_api::ConfigureHost& message, int* size);
+  static IOBufferRefPtr SendPairDevices(const pairing_api::PairDevices& message,
+                                        int* size);
+  static IOBufferRefPtr SendCompleteSetup(
+      const pairing_api::CompleteSetup& message, int* size);
+  static IOBufferRefPtr SendError(const pairing_api::Error& message, int* size);
+
+ private:
+  static IOBufferRefPtr SendMessage(uint8_t message_type,
+                                    const std::string& message,
+                                    int* size);
+
+  Observer* observer_;
+  MessageBuffer message_buffer_;
+  int next_message_type_;
+  int next_message_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProtoDecoder);
+};
+
+}  // namespace pairing_chromeos
+
+#endif  // COMPONENTS_PAIRING_PROTO_DECODER_H_