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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "remoting/protocol/negotiating_host_authenticator.h"
#include <memory>
#include <sstream>
#include <utility>
#include "base/check_op.h"
#include "base/containers/contains.h"
#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "base/functional/callback_helpers.h"
#include "base/notreached.h"
#include "base/strings/string_split.h"
#include "remoting/base/rsa_key_pair.h"
#include "remoting/protocol/channel_authenticator.h"
#include "remoting/protocol/credentials_type.h"
#include "remoting/protocol/host_authentication_config.h"
#include "remoting/protocol/pairing_host_authenticator.h"
#include "remoting/protocol/pairing_registry.h"
#include "remoting/protocol/session_authz_authenticator.h"
#include "remoting/protocol/spake2_authenticator.h"
#include "third_party/libjingle_xmpp/xmllite/xmlelement.h"
namespace remoting::protocol {
NegotiatingHostAuthenticator::NegotiatingHostAuthenticator(
std::string_view local_id,
std::string_view remote_id,
std::unique_ptr<HostAuthenticationConfig> config)
: NegotiatingAuthenticatorBase(WAITING_MESSAGE),
local_id_(local_id),
remote_id_(remote_id),
config_(std::move(config)) {
methods_ = config_->GetSupportedMethods();
DCHECK(!methods_.empty());
}
NegotiatingHostAuthenticator::~NegotiatingHostAuthenticator() = default;
void NegotiatingHostAuthenticator::ProcessMessage(
const jingle_xmpp::XmlElement* message,
base::OnceClosure resume_callback) {
DCHECK_EQ(state(), WAITING_MESSAGE);
state_ = PROCESSING_MESSAGE;
const jingle_xmpp::XmlElement* pairing_tag =
message->FirstNamed(kPairingInfoTag);
if (pairing_tag) {
client_id_ = pairing_tag->Attr(kClientIdAttribute);
}
std::string method_attr = message->Attr(kMethodAttributeQName);
AuthenticationMethod method = ParseAuthenticationMethodString(method_attr);
if (current_method_ != AuthenticationMethod::INVALID &&
method != current_method_) {
state_ = REJECTED;
rejection_reason_ = RejectionReason::INVALID_STATE;
rejection_details_ = RejectionDetails(
"The host has already chosen an authentication method. "
"The client cannot change it.");
std::move(resume_callback).Run();
return;
}
// If the client did not specify a preferred auth method, or specified an
// unknown or unsupported method, then select the first known method from
// the supported-methods attribute.
if (method == AuthenticationMethod::INVALID ||
!base::Contains(methods_, method)) {
method = AuthenticationMethod::INVALID;
std::string supported_methods_attr =
message->Attr(kSupportedMethodsAttributeQName);
if (supported_methods_attr.empty()) {
state_ = REJECTED;
rejection_reason_ = RejectionReason::INVALID_ARGUMENT;
rejection_details_ = RejectionDetails(
"Message contains neither the 'method' nor the 'supported-methods' "
"attributes.");
std::move(resume_callback).Run();
return;
}
// Find the first mutually-supported method in the client's list of
// supported-methods.
for (const std::string& method_str : base::SplitString(
supported_methods_attr, std::string(1, kSupportedMethodsSeparator),
base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL)) {
AuthenticationMethod value = ParseAuthenticationMethodString(method_str);
if (value != AuthenticationMethod::INVALID &&
base::Contains(methods_, value)) {
// Found common method.
method = value;
break;
}
}
if (method == AuthenticationMethod::INVALID) {
state_ = REJECTED;
rejection_reason_ = RejectionReason::NO_COMMON_AUTH_METHOD;
rejection_details_ = RejectionDetails(
"No common authentication method found between client and host.");
std::move(resume_callback).Run();
return;
}
// Drop the current message because we've chosen a different method.
current_method_ = method;
CreateAuthenticator(
MESSAGE_READY,
base::BindOnce(&NegotiatingHostAuthenticator::UpdateState,
base::Unretained(this), std::move(resume_callback)));
return;
}
// If the client specified a supported method, and the host hasn't chosen a
// method yet, use the client's preferred method and process the message.
if (current_method_ == AuthenticationMethod::INVALID) {
current_method_ = method;
// Copy the message since the authenticator may process it asynchronously.
CreateAuthenticator(
WAITING_MESSAGE,
base::BindOnce(&NegotiatingAuthenticatorBase::ProcessMessageInternal,
base::Unretained(this),
base::Owned(new jingle_xmpp::XmlElement(*message)),
std::move(resume_callback)));
return;
}
// If the client is using the host's current method, just process the message.
ProcessMessageInternal(message, std::move(resume_callback));
}
std::unique_ptr<jingle_xmpp::XmlElement>
NegotiatingHostAuthenticator::GetNextMessage() {
return GetNextMessageInternal();
}
void NegotiatingHostAuthenticator::CreateAuthenticator(
Authenticator::State preferred_initial_state,
base::OnceClosure resume_callback) {
DCHECK(current_method_ != AuthenticationMethod::INVALID);
switch (current_method_) {
case AuthenticationMethod::INVALID:
NOTREACHED();
case AuthenticationMethod::CLOUD_SESSION_AUTHZ_SPAKE2_CURVE25519: {
DCHECK_EQ(config_->session_authz_client_factory->method(),
AuthenticationMethod::CLOUD_SESSION_AUTHZ_SPAKE2_CURVE25519);
auto authenticator = std::make_unique<SessionAuthzAuthenticator>(
CredentialsType::CLOUD_SESSION_AUTHZ,
config_->session_authz_client_factory->Create(),
base::BindRepeating(&Spake2Authenticator::CreateForHost, local_id_,
remote_id_, config_->local_cert,
config_->key_pair));
authenticator->Start(std::move(resume_callback));
current_authenticator_ = std::move(authenticator);
break;
}
case AuthenticationMethod::CORP_SESSION_AUTHZ_SPAKE2_CURVE25519: {
DCHECK_EQ(config_->session_authz_client_factory->method(),
AuthenticationMethod::CORP_SESSION_AUTHZ_SPAKE2_CURVE25519);
auto authenticator = std::make_unique<SessionAuthzAuthenticator>(
CredentialsType::CORP_SESSION_AUTHZ,
config_->session_authz_client_factory->Create(),
base::BindRepeating(&Spake2Authenticator::CreateForHost, local_id_,
remote_id_, config_->local_cert,
config_->key_pair));
authenticator->Start(std::move(resume_callback));
current_authenticator_ = std::move(authenticator);
break;
}
case AuthenticationMethod::PAIRED_SPAKE2_CURVE25519: {
PairingHostAuthenticator* pairing_authenticator =
new PairingHostAuthenticator(
config_->pairing_registry,
base::BindRepeating(&Spake2Authenticator::CreateForHost,
local_id_, remote_id_, config_->local_cert,
config_->key_pair),
config_->shared_secret_hash);
current_authenticator_.reset(pairing_authenticator);
pairing_authenticator->Initialize(client_id_, preferred_initial_state,
std::move(resume_callback));
break;
}
case AuthenticationMethod::SHARED_SECRET_SPAKE2_CURVE25519:
current_authenticator_ = Spake2Authenticator::CreateForHost(
local_id_, remote_id_, config_->local_cert, config_->key_pair,
config_->shared_secret_hash, preferred_initial_state);
std::move(resume_callback).Run();
break;
}
ChainStateChangeAfterAcceptedWithUnderlying(*current_authenticator_);
}
} // namespace remoting::protocol
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