src/remoting/protocol/pairing_authenticator_base.cc

   1 // Copyright 2013 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/protocol/pairing_authenticator_base.h"
   6
   7 #include "base/bind.h"
   8 #include "remoting/base/constants.h"
   9 #include "remoting/protocol/channel_authenticator.h"
  10
  11 namespace remoting {
  12 namespace protocol {
  13
  14 const buzz::StaticQName PairingAuthenticatorBase::kPairingInfoTag =
  15     { kChromotingXmlNamespace, "pairing-info" };
  16 const buzz::StaticQName PairingAuthenticatorBase::kClientIdAttribute =
  17     { "", "client-id" };
  18
  19 namespace {
  20 const buzz::StaticQName kPairingFailedTag =
  21     { kChromotingXmlNamespace, "pairing-failed" };
  22 const buzz::StaticQName kPairingErrorAttribute = { "", "error" };
  23 }  // namespace
  24
  25 PairingAuthenticatorBase::PairingAuthenticatorBase()
  26     : using_paired_secret_(false),
  27       waiting_for_authenticator_(false),
  28       weak_factory_(this) {
  29 }
  30
  31 PairingAuthenticatorBase::~PairingAuthenticatorBase() {
  32 }
  33
  34 Authenticator::State PairingAuthenticatorBase::state() const {
  35   if (waiting_for_authenticator_) {
  36     return PROCESSING_MESSAGE;
  37   }
  38   return v2_authenticator_->state();
  39 }
  40
  41 Authenticator::RejectionReason
  42 PairingAuthenticatorBase::rejection_reason() const {
  43   if (!v2_authenticator_) {
  44     return PROTOCOL_ERROR;
  45   }
  46   return v2_authenticator_->rejection_reason();
  47 }
  48
  49 void PairingAuthenticatorBase::ProcessMessage(
  50     const buzz::XmlElement* message,
  51     const base::Closure& resume_callback) {
  52   DCHECK_EQ(state(), WAITING_MESSAGE);
  53
  54   // The client authenticator creates the underlying authenticator in the ctor
  55   // and the host creates it in response to the first message before deferring
  56   // to this class to process it. Either way, it should exist here.
  57   DCHECK(v2_authenticator_);
  58
  59   // If pairing failed, and we haven't already done so, try again with the PIN.
  60   if (using_paired_secret_ && HasErrorMessage(message)) {
  61     using_paired_secret_ = false;
  62     waiting_for_authenticator_ = true;
  63     v2_authenticator_.reset();
  64     SetAuthenticatorCallback set_authenticator = base::Bind(
  65         &PairingAuthenticatorBase::SetAuthenticatorAndProcessMessage,
  66         weak_factory_.GetWeakPtr(), base::Owned(new buzz::XmlElement(*message)),
  67         resume_callback);
  68     CreateV2AuthenticatorWithPIN(WAITING_MESSAGE, set_authenticator);
  69     return;
  70   }
  71
  72   // Pass the message to the underlying authenticator for processing, but
  73   // check for a failed SPAKE exchange if we're using the paired secret. In
  74   // this case the pairing protocol can continue by communicating the error
  75   // to the peer and retrying with the PIN.
  76   v2_authenticator_->ProcessMessage(
  77       message,
  78       base::Bind(&PairingAuthenticatorBase::CheckForFailedSpakeExchange,
  79                  weak_factory_.GetWeakPtr(), resume_callback));
  80 }
  81
  82 scoped_ptr<buzz::XmlElement> PairingAuthenticatorBase::GetNextMessage() {
  83   DCHECK_EQ(state(), MESSAGE_READY);
  84   scoped_ptr<buzz::XmlElement> result = v2_authenticator_->GetNextMessage();
  85   AddPairingElements(result.get());
  86   MaybeAddErrorMessage(result.get());
  87   return result.Pass();
  88 }
  89
  90 scoped_ptr<ChannelAuthenticator>
  91 PairingAuthenticatorBase::CreateChannelAuthenticator() const {
  92   return v2_authenticator_->CreateChannelAuthenticator();
  93 }
  94
  95 void PairingAuthenticatorBase::MaybeAddErrorMessage(buzz::XmlElement* message) {
  96   if (!error_message_.empty()) {
  97     buzz::XmlElement* pairing_failed_tag =
  98         new buzz::XmlElement(kPairingFailedTag);
  99     pairing_failed_tag->AddAttr(kPairingErrorAttribute, error_message_);
 100     message->AddElement(pairing_failed_tag);
 101     error_message_.clear();
 102   }
 103 }
 104
 105 bool PairingAuthenticatorBase::HasErrorMessage(
 106     const buzz::XmlElement* message) const {
 107   const buzz::XmlElement* pairing_failed_tag =
 108       message->FirstNamed(kPairingFailedTag);
 109   if (pairing_failed_tag) {
 110     std::string error = pairing_failed_tag->Attr(kPairingErrorAttribute);
 111     LOG(ERROR) << "Pairing failed: " << error;
 112   }
 113   return pairing_failed_tag != NULL;
 114 }
 115
 116 void PairingAuthenticatorBase::CheckForFailedSpakeExchange(
 117     const base::Closure& resume_callback) {
 118   // If the SPAKE exchange failed due to invalid credentials, and those
 119   // credentials were the paired secret, then notify the peer that the
 120   // PIN-less connection failed and retry using the PIN.
 121   if (v2_authenticator_->state() == REJECTED &&
 122       v2_authenticator_->rejection_reason() == INVALID_CREDENTIALS &&
 123       using_paired_secret_) {
 124     using_paired_secret_ = false;
 125     error_message_ = "invalid-shared-secret";
 126     v2_authenticator_.reset();
 127     buzz::XmlElement* no_message = NULL;
 128     SetAuthenticatorCallback set_authenticator = base::Bind(
 129         &PairingAuthenticatorBase::SetAuthenticatorAndProcessMessage,
 130         weak_factory_.GetWeakPtr(), no_message, resume_callback);
 131     CreateV2AuthenticatorWithPIN(MESSAGE_READY, set_authenticator);
 132     return;
 133   }
 134
 135   resume_callback.Run();
 136 }
 137
 138 void PairingAuthenticatorBase::SetAuthenticatorAndProcessMessage(
 139     const buzz::XmlElement* message,
 140     const base::Closure& resume_callback,
 141     scoped_ptr<Authenticator> authenticator) {
 142   DCHECK(!v2_authenticator_);
 143   DCHECK(authenticator);
 144   waiting_for_authenticator_ = false;
 145   v2_authenticator_ = authenticator.Pass();
 146   if (message) {
 147     ProcessMessage(message, resume_callback);
 148   } else {
 149     resume_callback.Run();
 150   }
 151 }
 152
 153 }  // namespace protocol
 154 }  // namespace remoting