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// Copyright 2013 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 "remoting/protocol/negotiating_client_authenticator.h"
#include <algorithm>
#include <sstream>
#include <utility>
#include "base/bind.h"
#include "base/callback.h"
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/strings/string_split.h"
#include "remoting/protocol/auth_util.h"
#include "remoting/protocol/channel_authenticator.h"
#include "remoting/protocol/pairing_client_authenticator.h"
#include "remoting/protocol/spake2_authenticator.h"
#include "remoting/protocol/v2_authenticator.h"
#include "third_party/libjingle_xmpp/xmllite/xmlelement.h"
namespace remoting {
namespace protocol {
NegotiatingClientAuthenticator::NegotiatingClientAuthenticator(
const std::string& local_id,
const std::string& remote_id,
const ClientAuthenticationConfig& config)
: NegotiatingAuthenticatorBase(MESSAGE_READY),
local_id_(local_id),
remote_id_(remote_id),
config_(config),
weak_factory_(this) {
if (!config_.fetch_third_party_token_callback.is_null()) {
AddMethod(Method::THIRD_PARTY_SPAKE2_CURVE25519);
AddMethod(Method::THIRD_PARTY_SPAKE2_P224);
}
AddMethod(Method::PAIRED_SPAKE2_CURVE25519);
AddMethod(Method::PAIRED_SPAKE2_P224);
AddMethod(Method::SHARED_SECRET_SPAKE2_CURVE25519);
AddMethod(Method::SHARED_SECRET_SPAKE2_P224);
AddMethod(Method::SHARED_SECRET_PLAIN_SPAKE2_P224);
}
NegotiatingClientAuthenticator::~NegotiatingClientAuthenticator() {}
void NegotiatingClientAuthenticator::ProcessMessage(
const buzz::XmlElement* message,
const base::Closure& resume_callback) {
DCHECK_EQ(state(), WAITING_MESSAGE);
state_ = PROCESSING_MESSAGE;
std::string method_attr = message->Attr(kMethodAttributeQName);
Method method = ParseMethodString(method_attr);
// The host picked a method different from the one the client had selected.
if (method != current_method_) {
// The host must pick a method that is valid and supported by the client,
// and it must not change methods after it has picked one.
if (method_set_by_host_ || method == Method::INVALID ||
std::find(methods_.begin(), methods_.end(), method) == methods_.end()) {
state_ = REJECTED;
rejection_reason_ = PROTOCOL_ERROR;
resume_callback.Run();
return;
}
current_method_ = method;
method_set_by_host_ = true;
// Copy the message since the authenticator may process it asynchronously.
base::Closure callback = base::Bind(
&NegotiatingAuthenticatorBase::ProcessMessageInternal,
base::Unretained(this), base::Owned(new buzz::XmlElement(*message)),
resume_callback);
CreateAuthenticatorForCurrentMethod(WAITING_MESSAGE, callback);
return;
}
ProcessMessageInternal(message, resume_callback);
}
std::unique_ptr<buzz::XmlElement>
NegotiatingClientAuthenticator::GetNextMessage() {
DCHECK_EQ(state(), MESSAGE_READY);
// This is the first message to the host, send a list of supported methods.
if (current_method_ == Method::INVALID) {
// If no authentication method has been chosen, see if we can optimistically
// choose one.
std::unique_ptr<buzz::XmlElement> result;
CreatePreferredAuthenticator();
if (current_authenticator_) {
DCHECK(current_authenticator_->state() == MESSAGE_READY);
result = GetNextMessageInternal();
} else {
result = CreateEmptyAuthenticatorMessage();
}
if (is_paired()) {
// If the client is paired with the host then attach pairing client_id to
// the message.
buzz::XmlElement* pairing_tag = new buzz::XmlElement(kPairingInfoTag);
result->AddElement(pairing_tag);
pairing_tag->AddAttr(kClientIdAttribute, config_.pairing_client_id);
}
// Include a list of supported methods.
std::string supported_methods;
for (Method method : methods_) {
if (!supported_methods.empty())
supported_methods += kSupportedMethodsSeparator;
supported_methods += MethodToString(method);
}
result->AddAttr(kSupportedMethodsAttributeQName, supported_methods);
state_ = WAITING_MESSAGE;
return result;
}
return GetNextMessageInternal();
}
void NegotiatingClientAuthenticator::CreateAuthenticatorForCurrentMethod(
Authenticator::State preferred_initial_state,
const base::Closure& resume_callback) {
DCHECK_EQ(state(), PROCESSING_MESSAGE);
DCHECK(current_method_ != Method::INVALID);
switch (current_method_) {
case Method::INVALID:
NOTREACHED();
break;
case Method::THIRD_PARTY_SPAKE2_P224:
current_authenticator_.reset(new ThirdPartyClientAuthenticator(
base::Bind(&V2Authenticator::CreateForClient),
config_.fetch_third_party_token_callback));
resume_callback.Run();
break;
case Method::THIRD_PARTY_SPAKE2_CURVE25519:
current_authenticator_.reset(new ThirdPartyClientAuthenticator(
base::Bind(&Spake2Authenticator::CreateForClient, local_id_,
remote_id_),
config_.fetch_third_party_token_callback));
resume_callback.Run();
break;
case Method::PAIRED_SPAKE2_P224: {
PairingClientAuthenticator* pairing_authenticator =
new PairingClientAuthenticator(
config_, base::Bind(&V2Authenticator::CreateForClient));
current_authenticator_ = base::WrapUnique(pairing_authenticator);
pairing_authenticator->Start(preferred_initial_state, resume_callback);
break;
}
case Method::PAIRED_SPAKE2_CURVE25519: {
PairingClientAuthenticator* pairing_authenticator =
new PairingClientAuthenticator(
config_, base::Bind(&Spake2Authenticator::CreateForClient,
local_id_, remote_id_));
current_authenticator_ = base::WrapUnique(pairing_authenticator);
pairing_authenticator->Start(preferred_initial_state, resume_callback);
break;
}
case Method::SHARED_SECRET_PLAIN_SPAKE2_P224:
case Method::SHARED_SECRET_SPAKE2_P224:
case Method::SHARED_SECRET_SPAKE2_CURVE25519:
config_.fetch_secret_callback.Run(
false,
base::Bind(
&NegotiatingClientAuthenticator::CreateSharedSecretAuthenticator,
weak_factory_.GetWeakPtr(), preferred_initial_state,
resume_callback));
break;
}
}
void NegotiatingClientAuthenticator::CreatePreferredAuthenticator() {
if (is_paired() &&
std::find(methods_.begin(), methods_.end(), Method::PAIRED_SPAKE2_P224) !=
methods_.end()) {
PairingClientAuthenticator* pairing_authenticator =
new PairingClientAuthenticator(
config_, base::Bind(&V2Authenticator::CreateForClient));
current_authenticator_ = base::WrapUnique(pairing_authenticator);
pairing_authenticator->StartPaired(MESSAGE_READY);
current_method_ = Method::PAIRED_SPAKE2_P224;
}
}
void NegotiatingClientAuthenticator::CreateSharedSecretAuthenticator(
Authenticator::State initial_state,
const base::Closure& resume_callback,
const std::string& shared_secret) {
std::string shared_secret_hash =
(current_method_ == Method::SHARED_SECRET_PLAIN_SPAKE2_P224)
? shared_secret
: GetSharedSecretHash(config_.host_id, shared_secret);
if (current_method_ == Method::SHARED_SECRET_SPAKE2_CURVE25519) {
current_authenticator_ = Spake2Authenticator::CreateForClient(
local_id_, remote_id_, shared_secret_hash, initial_state);
} else {
current_authenticator_ =
V2Authenticator::CreateForClient(shared_secret_hash, initial_state);
}
resume_callback.Run();
}
bool NegotiatingClientAuthenticator::is_paired() {
return !config_.pairing_client_id.empty() && !config_.pairing_secret.empty();
}
} // namespace protocol
} // namespace remoting
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