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/*
* Copyright (c) 2017 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 "call/rtp_demuxer.h"
#include "absl/strings/string_view.h"
#include "call/rtp_packet_sink_interface.h"
#include "modules/rtp_rtcp/source/rtp_header_extensions.h"
#include "modules/rtp_rtcp/source/rtp_packet_received.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/strings/string_builder.h"
namespace webrtc {
namespace {
template <typename Container, typename Value>
size_t RemoveFromMultimapByValue(Container* multimap, const Value& value) {
size_t count = 0;
for (auto it = multimap->begin(); it != multimap->end();) {
if (it->second == value) {
it = multimap->erase(it);
++count;
} else {
++it;
}
}
return count;
}
template <typename Map, typename Value>
size_t RemoveFromMapByValue(Map* map, const Value& value) {
return EraseIf(*map, [&](const auto& elem) { return elem.second == value; });
}
// Temp fix: MID in SDP is allowed to be slightly longer than what's allowed
// in the RTP demuxer. Truncate if needed; this won't match, but it only
// makes sense in places that wouldn't use this for matching anyway.
// TODO(bugs.webrtc.org/12517): remove when length 16 is policed by parser.
std::string CheckMidLength(absl::string_view mid) {
std::string new_mid(mid);
if (new_mid.length() > BaseRtpStringExtension::kMaxValueSizeBytes) {
RTC_LOG(LS_WARNING) << "`mid` attribute too long. Truncating.";
new_mid.resize(BaseRtpStringExtension::kMaxValueSizeBytes);
}
return new_mid;
}
} // namespace
RtpDemuxerCriteria::RtpDemuxerCriteria(
absl::string_view mid,
absl::string_view rsid /*= absl::string_view()*/)
: mid_(CheckMidLength(mid)), rsid_(rsid) {}
RtpDemuxerCriteria::RtpDemuxerCriteria() = default;
RtpDemuxerCriteria::~RtpDemuxerCriteria() = default;
bool RtpDemuxerCriteria::operator==(const RtpDemuxerCriteria& other) const {
return mid_ == other.mid_ && rsid_ == other.rsid_ && ssrcs_ == other.ssrcs_ &&
payload_types_ == other.payload_types_;
}
bool RtpDemuxerCriteria::operator!=(const RtpDemuxerCriteria& other) const {
return !(*this == other);
}
std::string RtpDemuxerCriteria::ToString() const {
rtc::StringBuilder sb;
sb << "{mid: " << (mid_.empty() ? "<empty>" : mid_)
<< ", rsid: " << (rsid_.empty() ? "<empty>" : rsid_) << ", ssrcs: [";
for (auto ssrc : ssrcs_) {
sb << ssrc << ", ";
}
sb << "], payload_types = [";
for (auto pt : payload_types_) {
sb << pt << ", ";
}
sb << "]}";
return sb.Release();
}
// static
std::string RtpDemuxer::DescribePacket(const RtpPacketReceived& packet) {
rtc::StringBuilder sb;
sb << "PT=" << packet.PayloadType() << " SSRC=" << packet.Ssrc();
std::string mid;
if (packet.GetExtension<RtpMid>(&mid)) {
sb << " MID=" << mid;
}
std::string rsid;
if (packet.GetExtension<RtpStreamId>(&rsid)) {
sb << " RSID=" << rsid;
}
std::string rrsid;
if (packet.GetExtension<RepairedRtpStreamId>(&rrsid)) {
sb << " RRSID=" << rrsid;
}
return sb.Release();
}
RtpDemuxer::RtpDemuxer(bool use_mid /* = true*/) : use_mid_(use_mid) {}
RtpDemuxer::~RtpDemuxer() {
RTC_DCHECK(sink_by_mid_.empty());
RTC_DCHECK(sink_by_ssrc_.empty());
RTC_DCHECK(sinks_by_pt_.empty());
RTC_DCHECK(sink_by_mid_and_rsid_.empty());
RTC_DCHECK(sink_by_rsid_.empty());
}
bool RtpDemuxer::AddSink(const RtpDemuxerCriteria& criteria,
RtpPacketSinkInterface* sink) {
RTC_DCHECK(!criteria.payload_types().empty() || !criteria.ssrcs().empty() ||
!criteria.mid().empty() || !criteria.rsid().empty());
RTC_DCHECK(criteria.mid().empty() || IsLegalMidName(criteria.mid()));
RTC_DCHECK(criteria.rsid().empty() || IsLegalRsidName(criteria.rsid()));
RTC_DCHECK(sink);
// We return false instead of DCHECKing for logical conflicts with the new
// criteria because new sinks are created according to user-specified SDP and
// we do not want to crash due to a data validation error.
if (CriteriaWouldConflict(criteria)) {
RTC_LOG(LS_ERROR) << "Unable to add sink=" << sink
<< " due to conflicting criteria " << criteria.ToString();
return false;
}
if (!criteria.mid().empty()) {
if (criteria.rsid().empty()) {
sink_by_mid_.emplace(criteria.mid(), sink);
} else {
sink_by_mid_and_rsid_.emplace(
std::make_pair(criteria.mid(), criteria.rsid()), sink);
}
} else {
if (!criteria.rsid().empty()) {
sink_by_rsid_.emplace(criteria.rsid(), sink);
}
}
for (uint32_t ssrc : criteria.ssrcs()) {
sink_by_ssrc_.emplace(ssrc, sink);
}
for (uint8_t payload_type : criteria.payload_types()) {
sinks_by_pt_.emplace(payload_type, sink);
}
RefreshKnownMids();
RTC_DLOG(LS_INFO) << "Added sink = " << sink << " for criteria "
<< criteria.ToString();
return true;
}
bool RtpDemuxer::CriteriaWouldConflict(
const RtpDemuxerCriteria& criteria) const {
if (!criteria.mid().empty()) {
if (criteria.rsid().empty()) {
// If the MID is in the known_mids_ set, then there is already a sink
// added for this MID directly, or there is a sink already added with a
// MID, RSID pair for our MID and some RSID.
// Adding this criteria would cause one of these rules to be shadowed, so
// reject this new criteria.
if (known_mids_.find(criteria.mid()) != known_mids_.end()) {
RTC_LOG(LS_INFO) << criteria.ToString()
<< " would conflict with known mid";
return true;
}
} else {
// If the exact rule already exists, then reject this duplicate.
const auto sink_by_mid_and_rsid = sink_by_mid_and_rsid_.find(
std::make_pair(criteria.mid(), criteria.rsid()));
if (sink_by_mid_and_rsid != sink_by_mid_and_rsid_.end()) {
RTC_LOG(LS_INFO) << criteria.ToString()
<< " would conflict with existing sink = "
<< sink_by_mid_and_rsid->second
<< " by mid+rsid binding";
return true;
}
// If there is already a sink registered for the bare MID, then this
// criteria will never receive any packets because they will just be
// directed to that MID sink, so reject this new criteria.
const auto sink_by_mid = sink_by_mid_.find(criteria.mid());
if (sink_by_mid != sink_by_mid_.end()) {
RTC_LOG(LS_INFO) << criteria.ToString()
<< " would conflict with existing sink = "
<< sink_by_mid->second << " by mid binding";
return true;
}
}
}
for (uint32_t ssrc : criteria.ssrcs()) {
const auto sink_by_ssrc = sink_by_ssrc_.find(ssrc);
if (sink_by_ssrc != sink_by_ssrc_.end()) {
RTC_LOG(LS_INFO) << criteria.ToString()
<< " would conflict with existing sink = "
<< sink_by_ssrc->second << " binding by SSRC=" << ssrc;
return true;
}
}
// TODO(steveanton): May also sanity check payload types.
return false;
}
void RtpDemuxer::RefreshKnownMids() {
known_mids_.clear();
for (auto const& item : sink_by_mid_) {
const std::string& mid = item.first;
known_mids_.insert(mid);
}
for (auto const& item : sink_by_mid_and_rsid_) {
const std::string& mid = item.first.first;
known_mids_.insert(mid);
}
}
bool RtpDemuxer::AddSink(uint32_t ssrc, RtpPacketSinkInterface* sink) {
RtpDemuxerCriteria criteria;
criteria.ssrcs().insert(ssrc);
return AddSink(criteria, sink);
}
void RtpDemuxer::AddSink(absl::string_view rsid, RtpPacketSinkInterface* sink) {
RtpDemuxerCriteria criteria(absl::string_view() /* mid */, rsid);
AddSink(criteria, sink);
}
bool RtpDemuxer::RemoveSink(const RtpPacketSinkInterface* sink) {
RTC_DCHECK(sink);
size_t num_removed = RemoveFromMapByValue(&sink_by_mid_, sink) +
RemoveFromMapByValue(&sink_by_ssrc_, sink) +
RemoveFromMultimapByValue(&sinks_by_pt_, sink) +
RemoveFromMapByValue(&sink_by_mid_and_rsid_, sink) +
RemoveFromMapByValue(&sink_by_rsid_, sink);
RefreshKnownMids();
return num_removed > 0;
}
flat_set<uint32_t> RtpDemuxer::GetSsrcsForSink(
const RtpPacketSinkInterface* sink) const {
flat_set<uint32_t> ssrcs;
if (sink) {
for (const auto& it : sink_by_ssrc_) {
if (it.second == sink) {
ssrcs.insert(it.first);
}
}
}
return ssrcs;
}
bool RtpDemuxer::OnRtpPacket(const RtpPacketReceived& packet) {
RtpPacketSinkInterface* sink = ResolveSink(packet);
if (sink != nullptr) {
sink->OnRtpPacket(packet);
return true;
}
return false;
}
RtpPacketSinkInterface* RtpDemuxer::ResolveSink(
const RtpPacketReceived& packet) {
// See the BUNDLE spec for high level reference to this algorithm:
// https://tools.ietf.org/html/draft-ietf-mmusic-sdp-bundle-negotiation-38#section-10.2
// RSID and RRID are routed to the same sinks. If an RSID is specified on a
// repair packet, it should be ignored and the RRID should be used.
std::string packet_mid, packet_rsid;
bool has_mid = use_mid_ && packet.GetExtension<RtpMid>(&packet_mid);
bool has_rsid = packet.GetExtension<RepairedRtpStreamId>(&packet_rsid);
if (!has_rsid) {
has_rsid = packet.GetExtension<RtpStreamId>(&packet_rsid);
}
uint32_t ssrc = packet.Ssrc();
// The BUNDLE spec says to drop any packets with unknown MIDs, even if the
// SSRC is known/latched.
if (has_mid && known_mids_.find(packet_mid) == known_mids_.end()) {
return nullptr;
}
// Cache information we learn about SSRCs and IDs. We need to do this even if
// there isn't a rule/sink yet because we might add an MID/RSID rule after
// learning an MID/RSID<->SSRC association.
std::string* mid = nullptr;
if (has_mid) {
mid_by_ssrc_[ssrc] = packet_mid;
mid = &packet_mid;
} else {
// If the packet does not include a MID header extension, check if there is
// a latched MID for the SSRC.
const auto it = mid_by_ssrc_.find(ssrc);
if (it != mid_by_ssrc_.end()) {
mid = &it->second;
}
}
std::string* rsid = nullptr;
if (has_rsid) {
rsid_by_ssrc_[ssrc] = packet_rsid;
rsid = &packet_rsid;
} else {
// If the packet does not include an RRID/RSID header extension, check if
// there is a latched RSID for the SSRC.
const auto it = rsid_by_ssrc_.find(ssrc);
if (it != rsid_by_ssrc_.end()) {
rsid = &it->second;
}
}
// If MID and/or RSID is specified, prioritize that for demuxing the packet.
// The motivation behind the BUNDLE algorithm is that we trust these are used
// deliberately by senders and are more likely to be correct than SSRC/payload
// type which are included with every packet.
// TODO(steveanton): According to the BUNDLE spec, new SSRC mappings are only
// accepted if the packet's extended sequence number is
// greater than that of the last SSRC mapping update.
// https://tools.ietf.org/html/rfc7941#section-4.2.6
if (mid != nullptr) {
RtpPacketSinkInterface* sink_by_mid = ResolveSinkByMid(*mid, ssrc);
if (sink_by_mid != nullptr) {
return sink_by_mid;
}
// RSID is scoped to a given MID if both are included.
if (rsid != nullptr) {
RtpPacketSinkInterface* sink_by_mid_rsid =
ResolveSinkByMidRsid(*mid, *rsid, ssrc);
if (sink_by_mid_rsid != nullptr) {
return sink_by_mid_rsid;
}
}
// At this point, there is at least one sink added for this MID and an RSID
// but either the packet does not have an RSID or it is for a different
// RSID. This falls outside the BUNDLE spec so drop the packet.
return nullptr;
}
// RSID can be used without MID as long as they are unique.
if (rsid != nullptr) {
RtpPacketSinkInterface* sink_by_rsid = ResolveSinkByRsid(*rsid, ssrc);
if (sink_by_rsid != nullptr) {
return sink_by_rsid;
}
}
// We trust signaled SSRC more than payload type which is likely to conflict
// between streams.
const auto ssrc_sink_it = sink_by_ssrc_.find(ssrc);
if (ssrc_sink_it != sink_by_ssrc_.end()) {
return ssrc_sink_it->second;
}
// Legacy senders will only signal payload type, support that as last resort.
return ResolveSinkByPayloadType(packet.PayloadType(), ssrc);
}
RtpPacketSinkInterface* RtpDemuxer::ResolveSinkByMid(absl::string_view mid,
uint32_t ssrc) {
const auto it = sink_by_mid_.find(mid);
if (it != sink_by_mid_.end()) {
RtpPacketSinkInterface* sink = it->second;
AddSsrcSinkBinding(ssrc, sink);
return sink;
}
return nullptr;
}
RtpPacketSinkInterface* RtpDemuxer::ResolveSinkByMidRsid(absl::string_view mid,
absl::string_view rsid,
uint32_t ssrc) {
const auto it = sink_by_mid_and_rsid_.find(
std::make_pair(std::string(mid), std::string(rsid)));
if (it != sink_by_mid_and_rsid_.end()) {
RtpPacketSinkInterface* sink = it->second;
AddSsrcSinkBinding(ssrc, sink);
return sink;
}
return nullptr;
}
RtpPacketSinkInterface* RtpDemuxer::ResolveSinkByRsid(absl::string_view rsid,
uint32_t ssrc) {
const auto it = sink_by_rsid_.find(rsid);
if (it != sink_by_rsid_.end()) {
RtpPacketSinkInterface* sink = it->second;
AddSsrcSinkBinding(ssrc, sink);
return sink;
}
return nullptr;
}
RtpPacketSinkInterface* RtpDemuxer::ResolveSinkByPayloadType(
uint8_t payload_type,
uint32_t ssrc) {
const auto range = sinks_by_pt_.equal_range(payload_type);
if (range.first != range.second) {
auto it = range.first;
const auto end = range.second;
if (std::next(it) == end) {
RtpPacketSinkInterface* sink = it->second;
AddSsrcSinkBinding(ssrc, sink);
return sink;
}
}
return nullptr;
}
void RtpDemuxer::AddSsrcSinkBinding(uint32_t ssrc,
RtpPacketSinkInterface* sink) {
if (sink_by_ssrc_.size() >= kMaxSsrcBindings) {
RTC_LOG(LS_WARNING) << "New SSRC=" << ssrc
<< " sink binding ignored; limit of" << kMaxSsrcBindings
<< " bindings has been reached.";
return;
}
auto result = sink_by_ssrc_.emplace(ssrc, sink);
auto it = result.first;
bool inserted = result.second;
if (inserted) {
RTC_DLOG(LS_INFO) << "Added sink = " << sink
<< " binding with SSRC=" << ssrc;
} else if (it->second != sink) {
RTC_DLOG(LS_INFO) << "Updated sink = " << sink
<< " binding with SSRC=" << ssrc;
it->second = sink;
}
}
} // namespace webrtc