129 lines
4.4 KiB
C++
129 lines
4.4 KiB
C++
/*
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* Copyright 2012 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/p2p/base/transportdescriptionfactory.h"
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#include <memory>
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#include "webrtc/p2p/base/transportdescription.h"
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#include "webrtc/base/helpers.h"
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#include "webrtc/base/logging.h"
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#include "webrtc/base/messagedigest.h"
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#include "webrtc/base/sslfingerprint.h"
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namespace cricket {
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TransportDescriptionFactory::TransportDescriptionFactory()
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: secure_(SEC_DISABLED) {
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}
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TransportDescription* TransportDescriptionFactory::CreateOffer(
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const TransportOptions& options,
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const TransportDescription* current_description) const {
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std::unique_ptr<TransportDescription> desc(new TransportDescription());
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// Generate the ICE credentials if we don't already have them.
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if (!current_description || options.ice_restart) {
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desc->ice_ufrag = rtc::CreateRandomString(ICE_UFRAG_LENGTH);
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desc->ice_pwd = rtc::CreateRandomString(ICE_PWD_LENGTH);
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} else {
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desc->ice_ufrag = current_description->ice_ufrag;
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desc->ice_pwd = current_description->ice_pwd;
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}
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// If we are trying to establish a secure transport, add a fingerprint.
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if (secure_ == SEC_ENABLED || secure_ == SEC_REQUIRED) {
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// Fail if we can't create the fingerprint.
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// If we are the initiator set role to "actpass".
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if (!SetSecurityInfo(desc.get(), CONNECTIONROLE_ACTPASS)) {
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return NULL;
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}
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}
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return desc.release();
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}
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TransportDescription* TransportDescriptionFactory::CreateAnswer(
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const TransportDescription* offer,
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const TransportOptions& options,
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const TransportDescription* current_description) const {
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// TODO(juberti): Figure out why we get NULL offers, and fix this upstream.
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if (!offer) {
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LOG(LS_WARNING) << "Failed to create TransportDescription answer " <<
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"because offer is NULL";
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return NULL;
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}
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std::unique_ptr<TransportDescription> desc(new TransportDescription());
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// Generate the ICE credentials if we don't already have them or ice is
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// being restarted.
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if (!current_description || options.ice_restart) {
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desc->ice_ufrag = rtc::CreateRandomString(ICE_UFRAG_LENGTH);
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desc->ice_pwd = rtc::CreateRandomString(ICE_PWD_LENGTH);
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} else {
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desc->ice_ufrag = current_description->ice_ufrag;
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desc->ice_pwd = current_description->ice_pwd;
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}
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// Negotiate security params.
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if (offer && offer->identity_fingerprint.get()) {
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// The offer supports DTLS, so answer with DTLS, as long as we support it.
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if (secure_ == SEC_ENABLED || secure_ == SEC_REQUIRED) {
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// Fail if we can't create the fingerprint.
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// Setting DTLS role to active.
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ConnectionRole role = (options.prefer_passive_role) ?
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CONNECTIONROLE_PASSIVE : CONNECTIONROLE_ACTIVE;
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if (!SetSecurityInfo(desc.get(), role)) {
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return NULL;
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}
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}
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} else if (secure_ == SEC_REQUIRED) {
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// We require DTLS, but the other side didn't offer it. Fail.
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LOG(LS_WARNING) << "Failed to create TransportDescription answer "
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"because of incompatible security settings";
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return NULL;
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}
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return desc.release();
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}
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bool TransportDescriptionFactory::SetSecurityInfo(
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TransportDescription* desc, ConnectionRole role) const {
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if (!certificate_) {
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LOG(LS_ERROR) << "Cannot create identity digest with no certificate";
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return false;
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}
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// This digest algorithm is used to produce the a=fingerprint lines in SDP.
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// RFC 4572 Section 5 requires that those lines use the same hash function as
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// the certificate's signature.
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std::string digest_alg;
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if (!certificate_->ssl_certificate().GetSignatureDigestAlgorithm(
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&digest_alg)) {
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LOG(LS_ERROR) << "Failed to retrieve the certificate's digest algorithm";
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return false;
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}
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desc->identity_fingerprint.reset(
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rtc::SSLFingerprint::Create(digest_alg, certificate_->identity()));
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if (!desc->identity_fingerprint.get()) {
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LOG(LS_ERROR) << "Failed to create identity fingerprint, alg="
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<< digest_alg;
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return false;
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}
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// Assign security role.
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desc->connection_role = role;
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return true;
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}
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} // namespace cricket
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