remoting/protocol/v2_authenticator.cc

   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/protocol/v2_authenticator.h"
   6
   7 #include "base/base64.h"
   8 #include "base/logging.h"
   9 #include "remoting/base/constants.h"
  10 #include "remoting/base/rsa_key_pair.h"
  11 #include "remoting/protocol/ssl_hmac_channel_authenticator.h"
  12 #include "third_party/webrtc/libjingle/xmllite/xmlelement.h"
  13
  14 using crypto::P224EncryptedKeyExchange;
  15
  16 #if defined(_WIN32) && defined(GetMessage)
  17 #undef GetMessage
  18 #endif
  19
  20 namespace remoting {
  21 namespace protocol {
  22
  23 namespace {
  24
  25 const buzz::StaticQName kEkeTag = { kChromotingXmlNamespace,
  26                                     "eke-message" };
  27 const buzz::StaticQName kCertificateTag = { kChromotingXmlNamespace,
  28                                             "certificate" };
  29
  30 }  // namespace
  31
  32 // static
  33 bool V2Authenticator::IsEkeMessage(const buzz::XmlElement* message) {
  34   return message->FirstNamed(kEkeTag) != NULL;
  35 }
  36
  37 // static
  38 scoped_ptr<Authenticator> V2Authenticator::CreateForClient(
  39     const std::string& shared_secret,
  40     Authenticator::State initial_state) {
  41   return make_scoped_ptr(new V2Authenticator(
  42       P224EncryptedKeyExchange::kPeerTypeClient, shared_secret, initial_state));
  43 }
  44
  45 // static
  46 scoped_ptr<Authenticator> V2Authenticator::CreateForHost(
  47     const std::string& local_cert,
  48     scoped_refptr<RsaKeyPair> key_pair,
  49     const std::string& shared_secret,
  50     Authenticator::State initial_state) {
  51   scoped_ptr<V2Authenticator> result(new V2Authenticator(
  52       P224EncryptedKeyExchange::kPeerTypeServer, shared_secret, initial_state));
  53   result->local_cert_ = local_cert;
  54   result->local_key_pair_ = key_pair;
  55   return result.Pass();
  56 }
  57
  58 V2Authenticator::V2Authenticator(
  59     crypto::P224EncryptedKeyExchange::PeerType type,
  60     const std::string& shared_secret,
  61     Authenticator::State initial_state)
  62     : certificate_sent_(false),
  63       key_exchange_impl_(type, shared_secret),
  64       state_(initial_state),
  65       started_(false),
  66       rejection_reason_(INVALID_CREDENTIALS) {
  67   pending_messages_.push(key_exchange_impl_.GetMessage());
  68 }
  69
  70 V2Authenticator::~V2Authenticator() {
  71 }
  72
  73 Authenticator::State V2Authenticator::state() const {
  74   if (state_ == ACCEPTED && !pending_messages_.empty())
  75     return MESSAGE_READY;
  76   return state_;
  77 }
  78
  79 bool V2Authenticator::started() const {
  80   return started_;
  81 }
  82
  83 Authenticator::RejectionReason V2Authenticator::rejection_reason() const {
  84   DCHECK_EQ(state(), REJECTED);
  85   return rejection_reason_;
  86 }
  87
  88 void V2Authenticator::ProcessMessage(const buzz::XmlElement* message,
  89                                      const base::Closure& resume_callback) {
  90   ProcessMessageInternal(message);
  91   resume_callback.Run();
  92 }
  93
  94 void V2Authenticator::ProcessMessageInternal(const buzz::XmlElement* message) {
  95   DCHECK_EQ(state(), WAITING_MESSAGE);
  96
  97   // Parse the certificate.
  98   std::string base64_cert = message->TextNamed(kCertificateTag);
  99   if (!base64_cert.empty()) {
 100     if (!base::Base64Decode(base64_cert, &remote_cert_)) {
 101       LOG(WARNING) << "Failed to decode certificate received from the peer.";
 102       remote_cert_.clear();
 103     }
 104   }
 105
 106   // Client always expect certificate in the first message.
 107   if (!is_host_side() && remote_cert_.empty()) {
 108     LOG(WARNING) << "No valid host certificate.";
 109     state_ = REJECTED;
 110     rejection_reason_ = PROTOCOL_ERROR;
 111     return;
 112   }
 113
 114   const buzz::XmlElement* eke_element = message->FirstNamed(kEkeTag);
 115   if (!eke_element) {
 116     LOG(WARNING) << "No eke-message found.";
 117     state_ = REJECTED;
 118     rejection_reason_ = PROTOCOL_ERROR;
 119     return;
 120   }
 121
 122   for (; eke_element; eke_element = eke_element->NextNamed(kEkeTag)) {
 123     std::string base64_message = eke_element->BodyText();
 124     std::string spake_message;
 125     if (base64_message.empty() ||
 126         !base::Base64Decode(base64_message, &spake_message)) {
 127       LOG(WARNING) << "Failed to decode auth message received from the peer.";
 128       state_ = REJECTED;
 129       rejection_reason_ = PROTOCOL_ERROR;
 130       return;
 131     }
 132
 133     P224EncryptedKeyExchange::Result result =
 134         key_exchange_impl_.ProcessMessage(spake_message);
 135     started_ = true;
 136     switch (result) {
 137       case P224EncryptedKeyExchange::kResultPending:
 138         pending_messages_.push(key_exchange_impl_.GetMessage());
 139         break;
 140
 141       case P224EncryptedKeyExchange::kResultFailed:
 142         state_ = REJECTED;
 143         rejection_reason_ = INVALID_CREDENTIALS;
 144         return;
 145
 146       case P224EncryptedKeyExchange::kResultSuccess:
 147         auth_key_ = key_exchange_impl_.GetKey();
 148         state_ = ACCEPTED;
 149         return;
 150     }
 151   }
 152   state_ = MESSAGE_READY;
 153 }
 154
 155 scoped_ptr<buzz::XmlElement> V2Authenticator::GetNextMessage() {
 156   DCHECK_EQ(state(), MESSAGE_READY);
 157
 158   scoped_ptr<buzz::XmlElement> message = CreateEmptyAuthenticatorMessage();
 159
 160   DCHECK(!pending_messages_.empty());
 161   while (!pending_messages_.empty()) {
 162     const std::string& spake_message = pending_messages_.front();
 163     std::string base64_message;
 164     base::Base64Encode(spake_message, &base64_message);
 165
 166     buzz::XmlElement* eke_tag = new buzz::XmlElement(kEkeTag);
 167     eke_tag->SetBodyText(base64_message);
 168     message->AddElement(eke_tag);
 169
 170     pending_messages_.pop();
 171   }
 172
 173   if (!local_cert_.empty() && !certificate_sent_) {
 174     buzz::XmlElement* certificate_tag = new buzz::XmlElement(kCertificateTag);
 175     std::string base64_cert;
 176     base::Base64Encode(local_cert_, &base64_cert);
 177     certificate_tag->SetBodyText(base64_cert);
 178     message->AddElement(certificate_tag);
 179     certificate_sent_ = true;
 180   }
 181
 182   if (state_ != ACCEPTED) {
 183     state_ = WAITING_MESSAGE;
 184   }
 185   return message.Pass();
 186 }
 187
 188 scoped_ptr<ChannelAuthenticator>
 189 V2Authenticator::CreateChannelAuthenticator() const {
 190   DCHECK_EQ(state(), ACCEPTED);
 191   CHECK(!auth_key_.empty());
 192
 193   if (is_host_side()) {
 194     return SslHmacChannelAuthenticator::CreateForHost(
 195         local_cert_, local_key_pair_, auth_key_);
 196   } else {
 197     return SslHmacChannelAuthenticator::CreateForClient(
 198         remote_cert_, auth_key_);
 199   }
 200 }
 201
 202 bool V2Authenticator::is_host_side() const {
 203   return local_key_pair_.get() != NULL;
 204 }
 205
 206 }  // namespace protocol
 207 }  // namespace remoting