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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "remoting/host/heartbeat_sender.h"
      6 
      7 #include <math.h>
      8 
      9 #include "base/bind.h"
     10 #include "base/message_loop/message_loop_proxy.h"
     11 #include "base/rand_util.h"
     12 #include "base/strings/string_number_conversions.h"
     13 #include "base/strings/stringize_macros.h"
     14 #include "base/time/time.h"
     15 #include "remoting/base/constants.h"
     16 #include "remoting/base/logging.h"
     17 #include "remoting/host/server_log_entry.h"
     18 #include "remoting/jingle_glue/iq_sender.h"
     19 #include "remoting/jingle_glue/signal_strategy.h"
     20 #include "third_party/libjingle/source/talk/xmllite/xmlelement.h"
     21 #include "third_party/libjingle/source/talk/xmpp/constants.h"
     22 
     23 using buzz::QName;
     24 using buzz::XmlElement;
     25 
     26 namespace remoting {
     27 
     28 namespace {
     29 
     30 const char kHeartbeatQueryTag[] = "heartbeat";
     31 const char kHostIdAttr[] = "hostid";
     32 const char kHostVersionTag[] = "host-version";
     33 const char kHeartbeatSignatureTag[] = "signature";
     34 const char kSequenceIdAttr[] = "sequence-id";
     35 
     36 const char kErrorTag[] = "error";
     37 const char kNotFoundTag[] = "item-not-found";
     38 
     39 const char kHeartbeatResultTag[] = "heartbeat-result";
     40 const char kSetIntervalTag[] = "set-interval";
     41 const char kExpectedSequenceIdTag[] = "expected-sequence-id";
     42 
     43 const int64 kDefaultHeartbeatIntervalMs = 5 * 60 * 1000;  // 5 minutes.
     44 const int64 kResendDelayMs = 10 * 1000;  // 10 seconds.
     45 const int64 kResendDelayOnHostNotFoundMs = 10 * 1000; // 10 seconds.
     46 const int kMaxResendOnHostNotFoundCount = 12;  // 2 minutes (12 x 10 seconds).
     47 
     48 }  // namespace
     49 
     50 HeartbeatSender::HeartbeatSender(
     51     Listener* listener,
     52     const std::string& host_id,
     53     SignalStrategy* signal_strategy,
     54     scoped_refptr<RsaKeyPair> key_pair,
     55     const std::string& directory_bot_jid)
     56     : listener_(listener),
     57       host_id_(host_id),
     58       signal_strategy_(signal_strategy),
     59       key_pair_(key_pair),
     60       directory_bot_jid_(directory_bot_jid),
     61       interval_ms_(kDefaultHeartbeatIntervalMs),
     62       sequence_id_(0),
     63       sequence_id_was_set_(false),
     64       sequence_id_recent_set_num_(0),
     65       heartbeat_succeeded_(false),
     66       failed_startup_heartbeat_count_(0) {
     67   DCHECK(signal_strategy_);
     68   DCHECK(key_pair_.get());
     69 
     70   signal_strategy_->AddListener(this);
     71 
     72   // Start heartbeats if the |signal_strategy_| is already connected.
     73   OnSignalStrategyStateChange(signal_strategy_->GetState());
     74 }
     75 
     76 HeartbeatSender::~HeartbeatSender() {
     77   signal_strategy_->RemoveListener(this);
     78 }
     79 
     80 void HeartbeatSender::OnSignalStrategyStateChange(SignalStrategy::State state) {
     81   if (state == SignalStrategy::CONNECTED) {
     82     iq_sender_.reset(new IqSender(signal_strategy_));
     83     SendStanza();
     84     timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(interval_ms_),
     85                  this, &HeartbeatSender::SendStanza);
     86   } else if (state == SignalStrategy::DISCONNECTED) {
     87     request_.reset();
     88     iq_sender_.reset();
     89     timer_.Stop();
     90     timer_resend_.Stop();
     91   }
     92 }
     93 
     94 bool HeartbeatSender::OnSignalStrategyIncomingStanza(
     95     const buzz::XmlElement* stanza) {
     96   return false;
     97 }
     98 
     99 void HeartbeatSender::SendStanza() {
    100   DoSendStanza();
    101   // Make sure we don't send another heartbeat before the heartbeat interval
    102   // has expired.
    103   timer_resend_.Stop();
    104 }
    105 
    106 void HeartbeatSender::ResendStanza() {
    107   DoSendStanza();
    108   // Make sure we don't send another heartbeat before the heartbeat interval
    109   // has expired.
    110   timer_.Reset();
    111 }
    112 
    113 void HeartbeatSender::DoSendStanza() {
    114   VLOG(1) << "Sending heartbeat stanza to " << directory_bot_jid_;
    115   request_ = iq_sender_->SendIq(
    116       buzz::STR_SET, directory_bot_jid_, CreateHeartbeatMessage(),
    117       base::Bind(&HeartbeatSender::ProcessResponse,
    118                  base::Unretained(this)));
    119   ++sequence_id_;
    120 }
    121 
    122 void HeartbeatSender::ProcessResponse(IqRequest* request,
    123                                       const XmlElement* response) {
    124   std::string type = response->Attr(buzz::QN_TYPE);
    125   if (type == buzz::STR_ERROR) {
    126     const XmlElement* error_element =
    127         response->FirstNamed(QName(buzz::NS_CLIENT, kErrorTag));
    128     if (error_element) {
    129       if (error_element->FirstNamed(QName(buzz::NS_STANZA, kNotFoundTag))) {
    130         LOG(ERROR) << "Received error: Host ID not found";
    131         // If the host was registered immediately before it sends a heartbeat,
    132         // then server-side latency may prevent the server recognizing the
    133         // host ID in the heartbeat. So even if all of the first few heartbeats
    134         // get a "host ID not found" error, that's not a good enough reason to
    135         // exit.
    136         failed_startup_heartbeat_count_++;
    137         if (!heartbeat_succeeded_ && (failed_startup_heartbeat_count_ <=
    138                 kMaxResendOnHostNotFoundCount)) {
    139           timer_resend_.Start(FROM_HERE,
    140                               base::TimeDelta::FromMilliseconds(
    141                                   kResendDelayOnHostNotFoundMs),
    142                               this,
    143                               &HeartbeatSender::ResendStanza);
    144           return;
    145         }
    146         listener_->OnUnknownHostIdError();
    147         return;
    148       }
    149     }
    150 
    151     LOG(ERROR) << "Received error in response to heartbeat: "
    152                << response->Str();
    153     return;
    154   }
    155 
    156   // Notify listener of the first successful heartbeat.
    157   if (!heartbeat_succeeded_) {
    158     listener_->OnHeartbeatSuccessful();
    159   }
    160   heartbeat_succeeded_ = true;
    161 
    162   // This method must only be called for error or result stanzas.
    163   DCHECK_EQ(std::string(buzz::STR_RESULT), type);
    164 
    165   const XmlElement* result_element =
    166       response->FirstNamed(QName(kChromotingXmlNamespace, kHeartbeatResultTag));
    167   if (result_element) {
    168     const XmlElement* set_interval_element =
    169         result_element->FirstNamed(QName(kChromotingXmlNamespace,
    170                                          kSetIntervalTag));
    171     if (set_interval_element) {
    172       const std::string& interval_str = set_interval_element->BodyText();
    173       int interval;
    174       if (!base::StringToInt(interval_str, &interval) || interval <= 0) {
    175         LOG(ERROR) << "Received invalid set-interval: "
    176                    << set_interval_element->Str();
    177       } else {
    178         SetInterval(interval * base::Time::kMillisecondsPerSecond);
    179       }
    180     }
    181 
    182     bool did_set_sequence_id = false;
    183     const XmlElement* expected_sequence_id_element =
    184         result_element->FirstNamed(QName(kChromotingXmlNamespace,
    185                                          kExpectedSequenceIdTag));
    186     if (expected_sequence_id_element) {
    187       // The sequence ID sent in the previous heartbeat was not what the server
    188       // expected, so send another heartbeat with the expected sequence ID.
    189       const std::string& expected_sequence_id_str =
    190           expected_sequence_id_element->BodyText();
    191       int expected_sequence_id;
    192       if (!base::StringToInt(expected_sequence_id_str, &expected_sequence_id)) {
    193         LOG(ERROR) << "Received invalid " << kExpectedSequenceIdTag << ": " <<
    194             expected_sequence_id_element->Str();
    195       } else {
    196         SetSequenceId(expected_sequence_id);
    197         sequence_id_recent_set_num_++;
    198         did_set_sequence_id = true;
    199       }
    200     }
    201     if (!did_set_sequence_id) {
    202       sequence_id_recent_set_num_ = 0;
    203     }
    204   }
    205 }
    206 
    207 void HeartbeatSender::SetInterval(int interval) {
    208   if (interval != interval_ms_) {
    209     interval_ms_ = interval;
    210 
    211     // Restart the timer with the new interval.
    212     if (timer_.IsRunning()) {
    213       timer_.Stop();
    214       timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(interval_ms_),
    215                    this, &HeartbeatSender::SendStanza);
    216     }
    217   }
    218 }
    219 
    220 void HeartbeatSender::SetSequenceId(int sequence_id) {
    221   sequence_id_ = sequence_id;
    222   // Setting the sequence ID may be a symptom of a temporary server-side
    223   // problem, which would affect many hosts, so don't send a new heartbeat
    224   // immediately, as many hosts doing so may overload the server.
    225   // But the server will usually set the sequence ID when it receives the first
    226   // heartbeat from a host. In that case, we can send a new heartbeat
    227   // immediately, as that only happens once per host instance.
    228   if (!sequence_id_was_set_) {
    229     ResendStanza();
    230   } else {
    231     HOST_LOG << "The heartbeat sequence ID has been set more than once: "
    232               << "the new value is " << sequence_id;
    233     double delay = pow(2.0, sequence_id_recent_set_num_) *
    234         (1 + base::RandDouble()) * kResendDelayMs;
    235     if (delay <= interval_ms_) {
    236       timer_resend_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(delay),
    237                           this, &HeartbeatSender::ResendStanza);
    238     }
    239   }
    240   sequence_id_was_set_ = true;
    241 }
    242 
    243 scoped_ptr<XmlElement> HeartbeatSender::CreateHeartbeatMessage() {
    244   // Create heartbeat stanza.
    245   scoped_ptr<XmlElement> heartbeat(new XmlElement(
    246       QName(kChromotingXmlNamespace, kHeartbeatQueryTag)));
    247   heartbeat->AddAttr(QName(kChromotingXmlNamespace, kHostIdAttr), host_id_);
    248   heartbeat->AddAttr(QName(kChromotingXmlNamespace, kSequenceIdAttr),
    249                  base::IntToString(sequence_id_));
    250   heartbeat->AddElement(CreateSignature().release());
    251   // Append host version.
    252   scoped_ptr<XmlElement> version_tag(new XmlElement(
    253       QName(kChromotingXmlNamespace, kHostVersionTag)));
    254   version_tag->AddText(STRINGIZE(VERSION));
    255   heartbeat->AddElement(version_tag.release());
    256   // Append log message (which isn't signed).
    257   scoped_ptr<XmlElement> log(ServerLogEntry::MakeStanza());
    258   scoped_ptr<ServerLogEntry> log_entry(ServerLogEntry::MakeForHeartbeat());
    259   log_entry->AddHostFields();
    260   log->AddElement(log_entry->ToStanza().release());
    261   heartbeat->AddElement(log.release());
    262   return heartbeat.Pass();
    263 }
    264 
    265 scoped_ptr<XmlElement> HeartbeatSender::CreateSignature() {
    266   scoped_ptr<XmlElement> signature_tag(new XmlElement(
    267       QName(kChromotingXmlNamespace, kHeartbeatSignatureTag)));
    268 
    269   std::string message = signal_strategy_->GetLocalJid() + ' ' +
    270       base::IntToString(sequence_id_);
    271   std::string signature(key_pair_->SignMessage(message));
    272   signature_tag->AddText(signature);
    273 
    274   return signature_tag.Pass();
    275 }
    276 
    277 }  // namespace remoting
    278