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/*
* Copyright 2012 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "p2p/base/transport_description_factory.h"
#include <stddef.h>
#include <memory>
#include <string>
#include "api/field_trials_view.h"
#include "p2p/base/ice_credentials_iterator.h"
#include "p2p/base/transport_description.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/ssl_fingerprint.h"
namespace webrtc {
TransportDescriptionFactory::TransportDescriptionFactory(
const FieldTrialsView& field_trials)
: field_trials_(field_trials) {}
TransportDescriptionFactory::~TransportDescriptionFactory() = default;
std::unique_ptr<TransportDescription> TransportDescriptionFactory::CreateOffer(
const TransportOptions& options,
const TransportDescription* current_description,
IceCredentialsIterator* ice_credentials) const {
auto desc = std::make_unique<TransportDescription>();
// Generate the ICE credentials if we don't already have them.
if (!current_description || options.ice_restart) {
IceParameters credentials = ice_credentials->GetIceCredentials();
desc->ice_ufrag = credentials.ufrag;
desc->ice_pwd = credentials.pwd;
} else {
desc->ice_ufrag = current_description->ice_ufrag;
desc->ice_pwd = current_description->ice_pwd;
}
desc->AddOption(ICE_OPTION_TRICKLE);
if (options.enable_ice_renomination) {
desc->AddOption(ICE_OPTION_RENOMINATION);
}
// If we are not trying to establish a secure transport, don't add a
// fingerprint.
if (insecure_ && !certificate_) {
return desc;
}
// Fail if we can't create the fingerprint.
// If we are the initiator set role to "actpass".
if (!SetSecurityInfo(desc.get(), CONNECTIONROLE_ACTPASS)) {
return nullptr;
}
return desc;
}
std::unique_ptr<TransportDescription> TransportDescriptionFactory::CreateAnswer(
const TransportDescription* offer,
const TransportOptions& options,
bool require_transport_attributes,
const TransportDescription* current_description,
IceCredentialsIterator* ice_credentials) const {
// TODO(juberti): Figure out why we get NULL offers, and fix this upstream.
if (!offer) {
RTC_LOG(LS_WARNING) << "Failed to create TransportDescription answer "
"because offer is NULL";
return nullptr;
}
auto desc = std::make_unique<TransportDescription>();
// Generate the ICE credentials if we don't already have them or ice is
// being restarted.
if (!current_description || options.ice_restart) {
IceParameters credentials = ice_credentials->GetIceCredentials();
desc->ice_ufrag = credentials.ufrag;
desc->ice_pwd = credentials.pwd;
} else {
desc->ice_ufrag = current_description->ice_ufrag;
desc->ice_pwd = current_description->ice_pwd;
}
desc->AddOption(ICE_OPTION_TRICKLE);
if (options.enable_ice_renomination) {
desc->AddOption(ICE_OPTION_RENOMINATION);
}
// Special affordance for testing: Answer without DTLS params
// if we are insecure without a certificate, or if we are
// insecure with a non-DTLS offer.
if ((!certificate_ || !offer->identity_fingerprint.get()) && insecure()) {
return desc;
}
if (!offer->identity_fingerprint.get()) {
if (require_transport_attributes) {
// We require DTLS, but the other side didn't offer it. Fail.
RTC_LOG(LS_WARNING) << "Failed to create TransportDescription answer "
"because of incompatible security settings";
return nullptr;
}
// This may be a bundled section, fingerprint may legitimately be missing.
return desc;
}
// Negotiate security params.
// The offer supports DTLS, so answer with DTLS.
RTC_CHECK(certificate_);
ConnectionRole role = CONNECTIONROLE_NONE;
// If the offer does not constrain the role, go with preference.
if (offer->connection_role == CONNECTIONROLE_ACTPASS) {
role = (options.prefer_passive_role) ? CONNECTIONROLE_PASSIVE
: CONNECTIONROLE_ACTIVE;
} else if (offer->connection_role == CONNECTIONROLE_ACTIVE) {
role = CONNECTIONROLE_PASSIVE;
} else if (offer->connection_role == CONNECTIONROLE_PASSIVE) {
role = CONNECTIONROLE_ACTIVE;
} else if (offer->connection_role == CONNECTIONROLE_NONE) {
// This case may be reached if a=setup is not present in the SDP.
RTC_LOG(LS_WARNING) << "Remote offer connection role is NONE, which is "
"a protocol violation";
role = (options.prefer_passive_role) ? CONNECTIONROLE_PASSIVE
: CONNECTIONROLE_ACTIVE;
} else {
RTC_LOG(LS_ERROR) << "Remote offer connection role is " << role
<< " which is a protocol violation";
RTC_DCHECK_NOTREACHED();
return nullptr;
}
if (!SetSecurityInfo(desc.get(), role)) {
return nullptr;
}
return desc;
}
bool TransportDescriptionFactory::SetSecurityInfo(TransportDescription* desc,
ConnectionRole role) const {
if (!certificate_) {
RTC_LOG(LS_ERROR) << "Cannot create identity digest with no certificate";
return false;
}
// This digest algorithm is used to produce the a=fingerprint lines in SDP.
// RFC 4572 Section 5 requires that those lines use the same hash function as
// the certificate's signature, which is what CreateFromCertificate does.
desc->identity_fingerprint =
SSLFingerprint::CreateFromCertificate(*certificate_);
if (!desc->identity_fingerprint) {
return false;
}
// Assign security role.
desc->connection_role = role;
return true;
}
} // namespace webrtc
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