webrtc/talk/p2p/base/transportdescriptionfactory.cc

178 lines
6.9 KiB
C++

/*
* libjingle
* Copyright 2012 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "talk/p2p/base/transportdescriptionfactory.h"
#include "talk/p2p/base/transportdescription.h"
#include "webrtc/base/helpers.h"
#include "webrtc/base/logging.h"
#include "webrtc/base/messagedigest.h"
#include "webrtc/base/scoped_ptr.h"
#include "webrtc/base/sslfingerprint.h"
namespace cricket {
static TransportProtocol kDefaultProtocol = ICEPROTO_GOOGLE;
TransportDescriptionFactory::TransportDescriptionFactory()
: protocol_(kDefaultProtocol),
secure_(SEC_DISABLED),
identity_(NULL) {
}
TransportDescription* TransportDescriptionFactory::CreateOffer(
const TransportOptions& options,
const TransportDescription* current_description) const {
rtc::scoped_ptr<TransportDescription> desc(new TransportDescription());
// Set the transport type depending on the selected protocol.
if (protocol_ == ICEPROTO_RFC5245) {
desc->transport_type = NS_JINGLE_ICE_UDP;
} else if (protocol_ == ICEPROTO_HYBRID) {
desc->transport_type = NS_JINGLE_ICE_UDP;
desc->AddOption(ICE_OPTION_GICE);
} else if (protocol_ == ICEPROTO_GOOGLE) {
desc->transport_type = NS_GINGLE_P2P;
}
// Generate the ICE credentials if we don't already have them.
if (!current_description || options.ice_restart) {
desc->ice_ufrag = rtc::CreateRandomString(ICE_UFRAG_LENGTH);
desc->ice_pwd = rtc::CreateRandomString(ICE_PWD_LENGTH);
} else {
desc->ice_ufrag = current_description->ice_ufrag;
desc->ice_pwd = current_description->ice_pwd;
}
// If we are trying to establish a secure transport, add a fingerprint.
if (secure_ == SEC_ENABLED || secure_ == SEC_REQUIRED) {
// Fail if we can't create the fingerprint.
// If we are the initiator set role to "actpass".
if (!SetSecurityInfo(desc.get(), CONNECTIONROLE_ACTPASS)) {
return NULL;
}
}
return desc.release();
}
TransportDescription* TransportDescriptionFactory::CreateAnswer(
const TransportDescription* offer,
const TransportOptions& options,
const TransportDescription* current_description) const {
// A NULL offer is treated as a GICE transport description.
// TODO(juberti): Figure out why we get NULL offers, and fix this upstream.
rtc::scoped_ptr<TransportDescription> desc(new TransportDescription());
// Figure out which ICE variant to negotiate; prefer RFC 5245 ICE, but fall
// back to G-ICE if needed. Note that we never create a hybrid answer, since
// we know what the other side can support already.
if (offer && offer->transport_type == NS_JINGLE_ICE_UDP &&
(protocol_ == ICEPROTO_RFC5245 || protocol_ == ICEPROTO_HYBRID)) {
// Offer is ICE or hybrid, we support ICE or hybrid: use ICE.
desc->transport_type = NS_JINGLE_ICE_UDP;
} else if (offer && offer->transport_type == NS_JINGLE_ICE_UDP &&
offer->HasOption(ICE_OPTION_GICE) &&
protocol_ == ICEPROTO_GOOGLE) {
desc->transport_type = NS_GINGLE_P2P;
// Offer is hybrid, we support GICE: use GICE.
} else if ((!offer || offer->transport_type == NS_GINGLE_P2P) &&
(protocol_ == ICEPROTO_HYBRID || protocol_ == ICEPROTO_GOOGLE)) {
// Offer is GICE, we support hybrid or GICE: use GICE.
desc->transport_type = NS_GINGLE_P2P;
} else {
// Mismatch.
LOG(LS_WARNING) << "Failed to create TransportDescription answer "
"because of incompatible transport types";
return NULL;
}
// Generate the ICE credentials if we don't already have them or ice is
// being restarted.
if (!current_description || options.ice_restart) {
desc->ice_ufrag = rtc::CreateRandomString(ICE_UFRAG_LENGTH);
desc->ice_pwd = rtc::CreateRandomString(ICE_PWD_LENGTH);
} else {
desc->ice_ufrag = current_description->ice_ufrag;
desc->ice_pwd = current_description->ice_pwd;
}
// Negotiate security params.
if (offer && offer->identity_fingerprint.get()) {
// The offer supports DTLS, so answer with DTLS, as long as we support it.
if (secure_ == SEC_ENABLED || secure_ == SEC_REQUIRED) {
// Fail if we can't create the fingerprint.
// Setting DTLS role to active.
ConnectionRole role = (options.prefer_passive_role) ?
CONNECTIONROLE_PASSIVE : CONNECTIONROLE_ACTIVE;
if (!SetSecurityInfo(desc.get(), role)) {
return NULL;
}
}
} else if (secure_ == SEC_REQUIRED) {
// We require DTLS, but the other side didn't offer it. Fail.
LOG(LS_WARNING) << "Failed to create TransportDescription answer "
"because of incompatible security settings";
return NULL;
}
return desc.release();
}
bool TransportDescriptionFactory::SetSecurityInfo(
TransportDescription* desc, ConnectionRole role) const {
if (!identity_) {
LOG(LS_ERROR) << "Cannot create identity digest with no identity";
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.
std::string digest_alg;
if (!identity_->certificate().GetSignatureDigestAlgorithm(&digest_alg)) {
LOG(LS_ERROR) << "Failed to retrieve the certificate's digest algorithm";
return false;
}
desc->identity_fingerprint.reset(
rtc::SSLFingerprint::Create(digest_alg, identity_));
if (!desc->identity_fingerprint.get()) {
LOG(LS_ERROR) << "Failed to create identity fingerprint, alg="
<< digest_alg;
return false;
}
// Assign security role.
desc->connection_role = role;
return true;
}
} // namespace cricket