src/notification/xmpp_channel.cc - weave/libweave - Git at Google

 // Copyright 2015 The Weave 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 "src/notification/xmpp_channel.h"

 #include <string>

 #include <base/bind.h>
 #include <weave/provider/network.h>
 #include <weave/provider/task_runner.h>

 #include "src/backoff_entry.h"
 #include "src/data_encoding.h"
 #include "src/notification/notification_delegate.h"
 #include "src/notification/notification_parser.h"
 #include "src/notification/xml_node.h"
 #include "src/privet/openssl_utils.h"
 #include "src/utils.h"

 namespace weave {

 namespace {

 std::string BuildXmppStartStreamCommand() {
   return "<stream:stream to='clouddevices.gserviceaccount.com' "
          "xmlns:stream='http://etherx.jabber.org/streams' "
          "xml:lang='*' version='1.0' xmlns='jabber:client'>";
 }

 std::string BuildXmppAuthenticateCommand(const std::string& account,
                                          const std::string& token) {
   std::vector<uint8_t> credentials;
   credentials.push_back(0);
   credentials.insert(credentials.end(), account.begin(), account.end());
   credentials.push_back(0);
   credentials.insert(credentials.end(), token.begin(), token.end());
   std::string msg =
       "<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' "
       "mechanism='X-OAUTH2' auth:service='oauth2' "
       "auth:allow-non-google-login='true' "
       "auth:client-uses-full-bind-result='true' "
       "xmlns:auth='http://www.google.com/talk/protocol/auth'>" +
       Base64Encode(credentials) + "</auth>";
   return msg;
 }

 // Backoff policy.
 // Note: In order to ensure a minimum of 20 seconds between server errors,
 // we have a 30s +- 10s (33%) jitter initial backoff.
 const BackoffEntry::Policy kDefaultBackoffPolicy = {
     // Number of initial errors (in sequence) to ignore before applying
     // exponential back-off rules.
     0,

     // Initial delay for exponential back-off in ms.
     30 * 1000,  // 30 seconds.

     // Factor by which the waiting time will be multiplied.
     2,

     // Fuzzing percentage. ex: 10% will spread requests randomly
     // between 90%-100% of the calculated time.
     0.33,  // 33%.

     // Maximum amount of time we are willing to delay our request in ms.
     10 * 60 * 1000,  // 10 minutes.

     // Time to keep an entry from being discarded even when it
     // has no significant state, -1 to never discard.
     -1,

     // Don't use initial delay unless the last request was an error.
     false,
 };

 const char kDefaultXmppHost[] = "talk.google.com";
 const uint16_t kDefaultXmppPort = 5223;

 // Used for keeping connection alive.
 const int kRegularPingIntervalSeconds = 60;
 const int kRegularPingTimeoutSeconds = 30;

 // Used for diagnostic when connectivity changed.
 const int kAgressivePingIntervalSeconds = 5;
 const int kAgressivePingTimeoutSeconds = 10;

 const int kConnectingTimeoutAfterNetChangeSeconds = 30;

 }  // namespace

 XmppChannel::XmppChannel(const std::string& account,
                          const std::string& access_token,
                          provider::TaskRunner* task_runner,
                          provider::Network* network)
     : account_{account},
       access_token_{access_token},
       network_{network},
       backoff_entry_{&kDefaultBackoffPolicy},
       task_runner_{task_runner},
       iq_stanza_handler_{new IqStanzaHandler{this, task_runner}} {
   read_socket_data_.resize(4096);
   if (network) {
     network->AddConnectionChangedCallback(base::Bind(
         &XmppChannel::OnConnectivityChanged, weak_ptr_factory_.GetWeakPtr()));
   }
 }

 void XmppChannel::OnMessageRead(size_t size, ErrorPtr error) {
   read_pending_ = false;
   if (error)
     return Restart();
   std::string msg(read_socket_data_.data(), size);
   VLOG(2) << "Received XMPP packet: '" << msg << "'";

   if (!size)
     return Restart();

   stream_parser_.ParseData(msg);
   WaitForMessage();
 }

 void XmppChannel::OnStreamStart(const std::string& node_name,
                                 std::map<std::string, std::string> attributes) {
   VLOG(2) << "XMPP stream start: " << node_name;
 }

 void XmppChannel::OnStreamEnd(const std::string& node_name) {
   VLOG(2) << "XMPP stream ended: " << node_name;
   Stop();
   if (IsConnected()) {
     // If we had a fully-established connection, restart it now.
     // However, if the connection has never been established yet (e.g.
     // authorization failed), do not restart right now. Wait till we get
     // new credentials.
     task_runner_->PostDelayedTask(
         FROM_HERE,
         base::Bind(&XmppChannel::Restart, task_ptr_factory_.GetWeakPtr()), {});
   } else if (delegate_) {
     delegate_->OnPermanentFailure();
   }
 }

 void XmppChannel::OnStanza(std::unique_ptr<XmlNode> stanza) {
   // Handle stanza asynchronously, since XmppChannel::OnStanza() is a callback
   // from expat XML parser and some stanza could cause the XMPP stream to be
   // reset and the parser to be re-initialized. We don't want to destroy the
   // parser while it is performing a callback invocation.
   task_runner_->PostDelayedTask(
       FROM_HERE,
       base::Bind(&XmppChannel::HandleStanza, task_ptr_factory_.GetWeakPtr(),
                  base::Passed(std::move(stanza))),
       {});
 }

 void XmppChannel::HandleStanza(std::unique_ptr<XmlNode> stanza) {
   VLOG(2) << "XMPP stanza received: " << stanza->ToString();

   switch (state_) {
     case XmppState::kConnected:
       if (stanza->name() == "stream:features") {
         auto children = stanza->FindChildren("mechanisms/mechanism", false);
         for (const auto& child : children) {
           if (child->text() == "X-OAUTH2") {
             state_ = XmppState::kAuthenticationStarted;
             SendMessage(BuildXmppAuthenticateCommand(account_, access_token_));
             return;
           }
         }
       }
       break;
     case XmppState::kAuthenticationStarted:
       if (stanza->name() == "success") {
         state_ = XmppState::kStreamRestartedPostAuthentication;
         RestartXmppStream();
         return;
       } else if (stanza->name() == "failure") {
         if (stanza->FindFirstChild("not-authorized", false)) {
           state_ = XmppState::kAuthenticationFailed;
           return;
         }
       }
       break;
     case XmppState::kStreamRestartedPostAuthentication:
       if (stanza->name() == "stream:features" &&
           stanza->FindFirstChild("bind", false)) {
         state_ = XmppState::kBindSent;
         iq_stanza_handler_->SendRequest(
             "set", "", "", "<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/>",
             base::Bind(&XmppChannel::OnBindCompleted,
                        task_ptr_factory_.GetWeakPtr()),
             base::Bind(&XmppChannel::Restart, task_ptr_factory_.GetWeakPtr()));
         return;
       }
       break;
     default:
       if (stanza->name() == "message") {
         HandleMessageStanza(std::move(stanza));
         return;
       } else if (stanza->name() == "iq") {
         if (!iq_stanza_handler_->HandleIqStanza(std::move(stanza))) {
           LOG(ERROR) << "Failed to handle IQ stanza";
           CloseStream();
         }
         return;
       }
       LOG(INFO) << "Unexpected XMPP stanza ignored: " << stanza->ToString();
       return;
   }
   // Something bad happened. Close the stream and start over.
   LOG(ERROR) << "Error condition occurred handling stanza: "
              << stanza->ToString() << " in state: " << static_cast<int>(state_);
   CloseStream();
 }

 void XmppChannel::CloseStream() {
   SendMessage("</stream:stream>");
 }

 void XmppChannel::OnBindCompleted(std::unique_ptr<XmlNode> reply) {
   if (reply->GetAttributeOrEmpty("type") != "result") {
     CloseStream();
     return;
   }
   const XmlNode* jid_node = reply->FindFirstChild("bind/jid", false);
   if (!jid_node) {
     LOG(ERROR) << "XMPP Bind response is missing JID";
     CloseStream();
     return;
   }

   jid_ = jid_node->text();
   state_ = XmppState::kSessionStarted;
   iq_stanza_handler_->SendRequest(
       "set", "", "", "<session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>",
       base::Bind(&XmppChannel::OnSessionEstablished,
                  task_ptr_factory_.GetWeakPtr()),
       base::Bind(&XmppChannel::Restart, task_ptr_factory_.GetWeakPtr()));
 }

 void XmppChannel::OnSessionEstablished(std::unique_ptr<XmlNode> reply) {
   if (reply->GetAttributeOrEmpty("type") != "result") {
     CloseStream();
     return;
   }
   state_ = XmppState::kSubscribeStarted;
   std::string body =
       "<subscribe xmlns='google:push'>"
       "<item channel='cloud_devices' from=''/></subscribe>";
   iq_stanza_handler_->SendRequest(
       "set", "", account_, body,
       base::Bind(&XmppChannel::OnSubscribed, task_ptr_factory_.GetWeakPtr()),
       base::Bind(&XmppChannel::Restart, task_ptr_factory_.GetWeakPtr()));
 }

 void XmppChannel::OnSubscribed(std::unique_ptr<XmlNode> reply) {
   if (reply->GetAttributeOrEmpty("type") != "result") {
     CloseStream();
     return;
   }
   state_ = XmppState::kSubscribed;
   if (delegate_)
     delegate_->OnConnected(GetName());
 }

 void XmppChannel::HandleMessageStanza(std::unique_ptr<XmlNode> stanza) {
   const XmlNode* node = stanza->FindFirstChild("push:push/push:data", true);
   if (!node) {
     LOG(WARNING) << "XMPP message stanza is missing <push:data> element";
     return;
   }
   std::string data = node->text();
   std::string json_data;
   if (!Base64Decode(data, &json_data)) {
     LOG(WARNING) << "Failed to decode base64-encoded message payload: " << data;
     return;
   }

   VLOG(2) << "XMPP push notification data: " << json_data;
   auto json_dict = LoadJsonDict(json_data, nullptr);
   if (json_dict && delegate_)
     ParseNotificationJson(*json_dict, delegate_, GetName());
 }

 void XmppChannel::CreateSslSocket() {
   CHECK(!stream_);
   state_ = XmppState::kConnecting;
   LOG(INFO) << "Starting XMPP connection to " << kDefaultXmppHost << ":"
             << kDefaultXmppPort;

   network_->OpenSslSocket(kDefaultXmppHost, kDefaultXmppPort,
                           base::Bind(&XmppChannel::OnSslSocketReady,
                                      task_ptr_factory_.GetWeakPtr()));
 }

 void XmppChannel::OnSslSocketReady(std::unique_ptr<Stream> stream,
                                    ErrorPtr error) {
   if (error) {
     LOG(ERROR) << "TLS handshake failed. Restarting XMPP connection";
     backoff_entry_.InformOfRequest(false);

     LOG(INFO) << "Delaying connection to XMPP server for "
               << backoff_entry_.GetTimeUntilRelease();
     return task_runner_->PostDelayedTask(
         FROM_HERE, base::Bind(&XmppChannel::CreateSslSocket,
                               task_ptr_factory_.GetWeakPtr()),
         backoff_entry_.GetTimeUntilRelease());
   }
   CHECK(XmppState::kConnecting == state_);
   backoff_entry_.InformOfRequest(true);
   stream_ = std::move(stream);
   state_ = XmppState::kConnected;
   RestartXmppStream();
   ScheduleRegularPing();
 }

 void XmppChannel::SendMessage(const std::string& message) {
   CHECK(stream_) << "No XMPP socket stream available";
   if (write_pending_) {
     queued_write_data_ += message;
     return;
   }
   write_socket_data_ = queued_write_data_ + message;
   queued_write_data_.clear();
   VLOG(2) << "Sending XMPP message: " << message;

   write_pending_ = true;
   stream_->Write(
       write_socket_data_.data(), write_socket_data_.size(),
       base::Bind(&XmppChannel::OnMessageSent, task_ptr_factory_.GetWeakPtr()));
 }

 void XmppChannel::OnMessageSent(ErrorPtr error) {
   write_pending_ = false;
   if (error)
     return Restart();
   if (queued_write_data_.empty()) {
     WaitForMessage();
   } else {
     SendMessage(std::string{});
   }
 }

 void XmppChannel::WaitForMessage() {
   if (read_pending_ || !stream_)
     return;

   read_pending_ = true;
   stream_->Read(
       read_socket_data_.data(), read_socket_data_.size(),
       base::Bind(&XmppChannel::OnMessageRead, task_ptr_factory_.GetWeakPtr()));
 }

 std::string XmppChannel::GetName() const {
   return "xmpp";
 }

 bool XmppChannel::IsConnected() const {
   return state_ == XmppState::kSubscribed;
 }

 void XmppChannel::AddChannelParameters(base::DictionaryValue* channel_json) {
   // No extra parameters needed for XMPP.
 }

 void XmppChannel::Restart() {
   LOG(INFO) << "Restarting XMPP";
   Stop();
   Start(delegate_);
 }

 void XmppChannel::Start(NotificationDelegate* delegate) {
   CHECK(state_ == XmppState::kNotStarted);
   delegate_ = delegate;

   CreateSslSocket();
 }

 void XmppChannel::Stop() {
   if (IsConnected() && delegate_)
     delegate_->OnDisconnected();

   task_ptr_factory_.InvalidateWeakPtrs();
   ping_ptr_factory_.InvalidateWeakPtrs();

   stream_.reset();
   state_ = XmppState::kNotStarted;
 }

 void XmppChannel::RestartXmppStream() {
   stream_parser_.Reset();
   stream_->CancelPendingOperations();
   read_pending_ = false;
   write_pending_ = false;
   SendMessage(BuildXmppStartStreamCommand());
 }

 void XmppChannel::SchedulePing(base::TimeDelta interval,
                                base::TimeDelta timeout) {
   VLOG(1) << "Next XMPP ping in " << interval << " with timeout " << timeout;
   ping_ptr_factory_.InvalidateWeakPtrs();
   task_runner_->PostDelayedTask(
       FROM_HERE, base::Bind(&XmppChannel::PingServer,
                             ping_ptr_factory_.GetWeakPtr(), timeout),
       interval);
 }

 void XmppChannel::ScheduleRegularPing() {
   SchedulePing(base::TimeDelta::FromSeconds(kRegularPingIntervalSeconds),
                base::TimeDelta::FromSeconds(kRegularPingTimeoutSeconds));
 }

 void XmppChannel::ScheduleFastPing() {
   SchedulePing(base::TimeDelta::FromSeconds(kAgressivePingIntervalSeconds),
                base::TimeDelta::FromSeconds(kAgressivePingTimeoutSeconds));
 }

 void XmppChannel::PingServer(base::TimeDelta timeout) {
   VLOG(1) << "Sending XMPP ping";
   if (!IsConnected()) {
     LOG(WARNING) << "XMPP channel is not connected";
     Restart();
     return;
   }

   // Send an XMPP Ping request as defined in XEP-0199 extension:
   // http://xmpp.org/extensions/xep-0199.html
   iq_stanza_handler_->SendRequestWithCustomTimeout(
       "get", jid_, account_, "<ping xmlns='urn:xmpp:ping'/>", timeout,
       base::Bind(&XmppChannel::OnPingResponse, task_ptr_factory_.GetWeakPtr(),
                  base::Time::Now()),
       base::Bind(&XmppChannel::OnPingTimeout, task_ptr_factory_.GetWeakPtr(),
                  base::Time::Now()));
 }

 void XmppChannel::OnPingResponse(base::Time sent_time,
                                  std::unique_ptr<XmlNode> reply) {
   VLOG(1) << "XMPP response received after " << (base::Time::Now() - sent_time);
   // Ping response received from server. Everything seems to be in order.
   // Reschedule with default intervals.
   ScheduleRegularPing();
 }

 void XmppChannel::OnPingTimeout(base::Time sent_time) {
   LOG(WARNING) << "XMPP channel seems to be disconnected. Ping timed out after "
                << (base::Time::Now() - sent_time);
   Restart();
 }

 void XmppChannel::OnConnectivityChanged() {
   if (state_ == XmppState::kNotStarted)
     return;

   if (state_ == XmppState::kConnecting &&
       backoff_entry_.GetTimeUntilRelease() <
           base::TimeDelta::FromSeconds(
               kConnectingTimeoutAfterNetChangeSeconds)) {
     VLOG(1) << "Next reconnect in " << backoff_entry_.GetTimeUntilRelease();
     return;
   }

   ScheduleFastPing();
 }

 }  // namespace weave
	// Copyright 2015 The Weave 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 "src/notification/xmpp_channel.h"

	#include <string>

	#include <base/bind.h>
	#include <weave/provider/network.h>
	#include <weave/provider/task_runner.h>

	#include "src/backoff_entry.h"
	#include "src/data_encoding.h"
	#include "src/notification/notification_delegate.h"
	#include "src/notification/notification_parser.h"
	#include "src/notification/xml_node.h"
	#include "src/privet/openssl_utils.h"
	#include "src/utils.h"

	namespace weave {

	namespace {

	std::string BuildXmppStartStreamCommand() {
	return "<stream:stream to='clouddevices.gserviceaccount.com' "
	"xmlns:stream='http://etherx.jabber.org/streams' "
	"xml:lang='*' version='1.0' xmlns='jabber:client'>";
	}

	std::string BuildXmppAuthenticateCommand(const std::string& account,
	const std::string& token) {
	std::vector<uint8_t> credentials;
	credentials.push_back(0);
	credentials.insert(credentials.end(), account.begin(), account.end());
	credentials.push_back(0);
	credentials.insert(credentials.end(), token.begin(), token.end());
	std::string msg =
	"<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' "
	"mechanism='X-OAUTH2' auth:service='oauth2' "
	"auth:allow-non-google-login='true' "
	"auth:client-uses-full-bind-result='true' "
	"xmlns:auth='http://www.google.com/talk/protocol/auth'>" +
	Base64Encode(credentials) + "</auth>";
	return msg;
	}

	// Backoff policy.
	// Note: In order to ensure a minimum of 20 seconds between server errors,
	// we have a 30s +- 10s (33%) jitter initial backoff.
	const BackoffEntry::Policy kDefaultBackoffPolicy = {
	// Number of initial errors (in sequence) to ignore before applying
	// exponential back-off rules.
	0,

	// Initial delay for exponential back-off in ms.
	30 * 1000, // 30 seconds.

	// Factor by which the waiting time will be multiplied.
	2,

	// Fuzzing percentage. ex: 10% will spread requests randomly
	// between 90%-100% of the calculated time.
	0.33, // 33%.

	// Maximum amount of time we are willing to delay our request in ms.
	10 * 60 * 1000, // 10 minutes.

	// Time to keep an entry from being discarded even when it
	// has no significant state, -1 to never discard.
	-1,

	// Don't use initial delay unless the last request was an error.
	false,
	};

	const char kDefaultXmppHost[] = "talk.google.com";
	const uint16_t kDefaultXmppPort = 5223;

	// Used for keeping connection alive.
	const int kRegularPingIntervalSeconds = 60;
	const int kRegularPingTimeoutSeconds = 30;

	// Used for diagnostic when connectivity changed.
	const int kAgressivePingIntervalSeconds = 5;
	const int kAgressivePingTimeoutSeconds = 10;

	const int kConnectingTimeoutAfterNetChangeSeconds = 30;

	} // namespace

	XmppChannel::XmppChannel(const std::string& account,
	const std::string& access_token,
	provider::TaskRunner* task_runner,
	provider::Network* network)
	: account_{account},
	access_token_{access_token},
	network_{network},
	backoff_entry_{&kDefaultBackoffPolicy},
	task_runner_{task_runner},
	iq_stanza_handler_{new IqStanzaHandler{this, task_runner}} {
	read_socket_data_.resize(4096);
	if (network) {
	network->AddConnectionChangedCallback(base::Bind(
	&XmppChannel::OnConnectivityChanged, weak_ptr_factory_.GetWeakPtr()));
	}
	}

	void XmppChannel::OnMessageRead(size_t size, ErrorPtr error) {
	read_pending_ = false;
	if (error)
	return Restart();
	std::string msg(read_socket_data_.data(), size);
	VLOG(2) << "Received XMPP packet: '" << msg << "'";

	if (!size)
	return Restart();

	stream_parser_.ParseData(msg);
	WaitForMessage();
	}

	void XmppChannel::OnStreamStart(const std::string& node_name,
	std::map<std::string, std::string> attributes) {
	VLOG(2) << "XMPP stream start: " << node_name;
	}

	void XmppChannel::OnStreamEnd(const std::string& node_name) {
	VLOG(2) << "XMPP stream ended: " << node_name;
	Stop();
	if (IsConnected()) {
	// If we had a fully-established connection, restart it now.
	// However, if the connection has never been established yet (e.g.
	// authorization failed), do not restart right now. Wait till we get
	// new credentials.
	task_runner_->PostDelayedTask(
	FROM_HERE,
	base::Bind(&XmppChannel::Restart, task_ptr_factory_.GetWeakPtr()), {});
	} else if (delegate_) {
	delegate_->OnPermanentFailure();
	}
	}

	void XmppChannel::OnStanza(std::unique_ptr<XmlNode> stanza) {
	// Handle stanza asynchronously, since XmppChannel::OnStanza() is a callback
	// from expat XML parser and some stanza could cause the XMPP stream to be
	// reset and the parser to be re-initialized. We don't want to destroy the
	// parser while it is performing a callback invocation.
	task_runner_->PostDelayedTask(
	FROM_HERE,
	base::Bind(&XmppChannel::HandleStanza, task_ptr_factory_.GetWeakPtr(),
	base::Passed(std::move(stanza))),
	{});
	}

	void XmppChannel::HandleStanza(std::unique_ptr<XmlNode> stanza) {
	VLOG(2) << "XMPP stanza received: " << stanza->ToString();

	switch (state_) {
	case XmppState::kConnected:
	if (stanza->name() == "stream:features") {
	auto children = stanza->FindChildren("mechanisms/mechanism", false);
	for (const auto& child : children) {
	if (child->text() == "X-OAUTH2") {
	state_ = XmppState::kAuthenticationStarted;
	SendMessage(BuildXmppAuthenticateCommand(account_, access_token_));
	return;
	}
	}
	}
	break;
	case XmppState::kAuthenticationStarted:
	if (stanza->name() == "success") {
	state_ = XmppState::kStreamRestartedPostAuthentication;
	RestartXmppStream();
	return;
	} else if (stanza->name() == "failure") {
	if (stanza->FindFirstChild("not-authorized", false)) {
	state_ = XmppState::kAuthenticationFailed;
	return;
	}
	}
	break;
	case XmppState::kStreamRestartedPostAuthentication:
	if (stanza->name() == "stream:features" &&
	stanza->FindFirstChild("bind", false)) {
	state_ = XmppState::kBindSent;
	iq_stanza_handler_->SendRequest(
	"set", "", "", "<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/>",
	base::Bind(&XmppChannel::OnBindCompleted,
	task_ptr_factory_.GetWeakPtr()),
	base::Bind(&XmppChannel::Restart, task_ptr_factory_.GetWeakPtr()));
	return;
	}
	break;
	default:
	if (stanza->name() == "message") {
	HandleMessageStanza(std::move(stanza));
	return;
	} else if (stanza->name() == "iq") {
	if (!iq_stanza_handler_->HandleIqStanza(std::move(stanza))) {
	LOG(ERROR) << "Failed to handle IQ stanza";
	CloseStream();
	}
	return;
	}
	LOG(INFO) << "Unexpected XMPP stanza ignored: " << stanza->ToString();
	return;
	}
	// Something bad happened. Close the stream and start over.
	LOG(ERROR) << "Error condition occurred handling stanza: "
	<< stanza->ToString() << " in state: " << static_cast<int>(state_);
	CloseStream();
	}

	void XmppChannel::CloseStream() {
	SendMessage("</stream:stream>");
	}

	void XmppChannel::OnBindCompleted(std::unique_ptr<XmlNode> reply) {
	if (reply->GetAttributeOrEmpty("type") != "result") {
	CloseStream();
	return;
	}
	const XmlNode* jid_node = reply->FindFirstChild("bind/jid", false);
	if (!jid_node) {
	LOG(ERROR) << "XMPP Bind response is missing JID";
	CloseStream();
	return;
	}

	jid_ = jid_node->text();
	state_ = XmppState::kSessionStarted;
	iq_stanza_handler_->SendRequest(
	"set", "", "", "<session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>",
	base::Bind(&XmppChannel::OnSessionEstablished,
	task_ptr_factory_.GetWeakPtr()),
	base::Bind(&XmppChannel::Restart, task_ptr_factory_.GetWeakPtr()));
	}

	void XmppChannel::OnSessionEstablished(std::unique_ptr<XmlNode> reply) {
	if (reply->GetAttributeOrEmpty("type") != "result") {
	CloseStream();
	return;
	}
	state_ = XmppState::kSubscribeStarted;
	std::string body =
	"<subscribe xmlns='google:push'>"
	"<item channel='cloud_devices' from=''/></subscribe>";
	iq_stanza_handler_->SendRequest(
	"set", "", account_, body,
	base::Bind(&XmppChannel::OnSubscribed, task_ptr_factory_.GetWeakPtr()),
	base::Bind(&XmppChannel::Restart, task_ptr_factory_.GetWeakPtr()));
	}

	void XmppChannel::OnSubscribed(std::unique_ptr<XmlNode> reply) {
	if (reply->GetAttributeOrEmpty("type") != "result") {
	CloseStream();
	return;
	}
	state_ = XmppState::kSubscribed;
	if (delegate_)
	delegate_->OnConnected(GetName());
	}

	void XmppChannel::HandleMessageStanza(std::unique_ptr<XmlNode> stanza) {
	const XmlNode* node = stanza->FindFirstChild("push:push/push:data", true);
	if (!node) {
	LOG(WARNING) << "XMPP message stanza is missing <push:data> element";
	return;
	}
	std::string data = node->text();
	std::string json_data;
	if (!Base64Decode(data, &json_data)) {
	LOG(WARNING) << "Failed to decode base64-encoded message payload: " << data;
	return;
	}

	VLOG(2) << "XMPP push notification data: " << json_data;
	auto json_dict = LoadJsonDict(json_data, nullptr);
	if (json_dict && delegate_)
	ParseNotificationJson(*json_dict, delegate_, GetName());
	}

	void XmppChannel::CreateSslSocket() {
	CHECK(!stream_);
	state_ = XmppState::kConnecting;
	LOG(INFO) << "Starting XMPP connection to " << kDefaultXmppHost << ":"
	<< kDefaultXmppPort;

	network_->OpenSslSocket(kDefaultXmppHost, kDefaultXmppPort,
	base::Bind(&XmppChannel::OnSslSocketReady,
	task_ptr_factory_.GetWeakPtr()));
	}

	void XmppChannel::OnSslSocketReady(std::unique_ptr<Stream> stream,
	ErrorPtr error) {
	if (error) {
	LOG(ERROR) << "TLS handshake failed. Restarting XMPP connection";
	backoff_entry_.InformOfRequest(false);

	LOG(INFO) << "Delaying connection to XMPP server for "
	<< backoff_entry_.GetTimeUntilRelease();
	return task_runner_->PostDelayedTask(
	FROM_HERE, base::Bind(&XmppChannel::CreateSslSocket,
	task_ptr_factory_.GetWeakPtr()),
	backoff_entry_.GetTimeUntilRelease());
	}
	CHECK(XmppState::kConnecting == state_);
	backoff_entry_.InformOfRequest(true);
	stream_ = std::move(stream);
	state_ = XmppState::kConnected;
	RestartXmppStream();
	ScheduleRegularPing();
	}

	void XmppChannel::SendMessage(const std::string& message) {
	CHECK(stream_) << "No XMPP socket stream available";
	if (write_pending_) {
	queued_write_data_ += message;
	return;
	}
	write_socket_data_ = queued_write_data_ + message;
	queued_write_data_.clear();
	VLOG(2) << "Sending XMPP message: " << message;

	write_pending_ = true;
	stream_->Write(
	write_socket_data_.data(), write_socket_data_.size(),
	base::Bind(&XmppChannel::OnMessageSent, task_ptr_factory_.GetWeakPtr()));
	}

	void XmppChannel::OnMessageSent(ErrorPtr error) {
	write_pending_ = false;
	if (error)
	return Restart();
	if (queued_write_data_.empty()) {
	WaitForMessage();
	} else {
	SendMessage(std::string{});
	}
	}

	void XmppChannel::WaitForMessage() {
	if (read_pending_ \|\| !stream_)
	return;

	read_pending_ = true;
	stream_->Read(
	read_socket_data_.data(), read_socket_data_.size(),
	base::Bind(&XmppChannel::OnMessageRead, task_ptr_factory_.GetWeakPtr()));
	}

	std::string XmppChannel::GetName() const {
	return "xmpp";
	}

	bool XmppChannel::IsConnected() const {
	return state_ == XmppState::kSubscribed;
	}

	void XmppChannel::AddChannelParameters(base::DictionaryValue* channel_json) {
	// No extra parameters needed for XMPP.
	}

	void XmppChannel::Restart() {
	LOG(INFO) << "Restarting XMPP";
	Stop();
	Start(delegate_);
	}

	void XmppChannel::Start(NotificationDelegate* delegate) {
	CHECK(state_ == XmppState::kNotStarted);
	delegate_ = delegate;

	CreateSslSocket();
	}

	void XmppChannel::Stop() {
	if (IsConnected() && delegate_)
	delegate_->OnDisconnected();

	task_ptr_factory_.InvalidateWeakPtrs();
	ping_ptr_factory_.InvalidateWeakPtrs();

	stream_.reset();
	state_ = XmppState::kNotStarted;
	}

	void XmppChannel::RestartXmppStream() {
	stream_parser_.Reset();
	stream_->CancelPendingOperations();
	read_pending_ = false;
	write_pending_ = false;
	SendMessage(BuildXmppStartStreamCommand());
	}

	void XmppChannel::SchedulePing(base::TimeDelta interval,
	base::TimeDelta timeout) {
	VLOG(1) << "Next XMPP ping in " << interval << " with timeout " << timeout;
	ping_ptr_factory_.InvalidateWeakPtrs();
	task_runner_->PostDelayedTask(
	FROM_HERE, base::Bind(&XmppChannel::PingServer,
	ping_ptr_factory_.GetWeakPtr(), timeout),
	interval);
	}

	void XmppChannel::ScheduleRegularPing() {
	SchedulePing(base::TimeDelta::FromSeconds(kRegularPingIntervalSeconds),
	base::TimeDelta::FromSeconds(kRegularPingTimeoutSeconds));
	}

	void XmppChannel::ScheduleFastPing() {
	SchedulePing(base::TimeDelta::FromSeconds(kAgressivePingIntervalSeconds),
	base::TimeDelta::FromSeconds(kAgressivePingTimeoutSeconds));
	}

	void XmppChannel::PingServer(base::TimeDelta timeout) {
	VLOG(1) << "Sending XMPP ping";
	if (!IsConnected()) {
	LOG(WARNING) << "XMPP channel is not connected";
	Restart();
	return;
	}

	// Send an XMPP Ping request as defined in XEP-0199 extension:
	// http://xmpp.org/extensions/xep-0199.html
	iq_stanza_handler_->SendRequestWithCustomTimeout(
	"get", jid_, account_, "<ping xmlns='urn:xmpp:ping'/>", timeout,
	base::Bind(&XmppChannel::OnPingResponse, task_ptr_factory_.GetWeakPtr(),
	base::Time::Now()),
	base::Bind(&XmppChannel::OnPingTimeout, task_ptr_factory_.GetWeakPtr(),
	base::Time::Now()));
	}

	void XmppChannel::OnPingResponse(base::Time sent_time,
	std::unique_ptr<XmlNode> reply) {
	VLOG(1) << "XMPP response received after " << (base::Time::Now() - sent_time);
	// Ping response received from server. Everything seems to be in order.
	// Reschedule with default intervals.
	ScheduleRegularPing();
	}

	void XmppChannel::OnPingTimeout(base::Time sent_time) {
	LOG(WARNING) << "XMPP channel seems to be disconnected. Ping timed out after "
	<< (base::Time::Now() - sent_time);
	Restart();
	}

	void XmppChannel::OnConnectivityChanged() {
	if (state_ == XmppState::kNotStarted)
	return;

	if (state_ == XmppState::kConnecting &&
	backoff_entry_.GetTimeUntilRelease() <
	base::TimeDelta::FromSeconds(
	kConnectingTimeoutAfterNetChangeSeconds)) {
	VLOG(1) << "Next reconnect in " << backoff_entry_.GetTimeUntilRelease();
	return;
	}

	ScheduleFastPing();
	}

	} // namespace weave