| /* |
| * Copyright 2018 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 "pc/simulcast_sdp_serializer.h" |
| |
| #include <algorithm> |
| #include <map> |
| #include <optional> |
| #include <string> |
| #include <utility> |
| #include <vector> |
| |
| #include "absl/algorithm/container.h" |
| #include "absl/strings/string_view.h" |
| #include "api/rtc_error.h" |
| #include "api/rtp_parameters.h" |
| #include "media/base/codec.h" |
| #include "media/base/codec_comparators.h" |
| #include "media/base/rid_description.h" |
| #include "modules/rtp_rtcp/include/rtp_rtcp_defines.h" |
| #include "pc/session_description.h" |
| #include "pc/simulcast_description.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/logging.h" |
| #include "rtc_base/string_encode.h" |
| #include "rtc_base/string_to_number.h" |
| #include "rtc_base/strings/string_builder.h" |
| |
| using ::webrtc::RidDescription; |
| using ::webrtc::RidDirection; |
| using ::webrtc::SimulcastDescription; |
| using ::webrtc::SimulcastLayer; |
| using ::webrtc::SimulcastLayerList; |
| |
| namespace webrtc { |
| |
| namespace { |
| |
| // delimiters |
| const char kDelimiterComma[] = ","; |
| const char kDelimiterCommaChar = ','; |
| const char kDelimiterEqual[] = "="; |
| const char kDelimiterEqualChar = '='; |
| const char kDelimiterSemicolon[] = ";"; |
| const char kDelimiterSemicolonChar = ';'; |
| const char kDelimiterSpace[] = " "; |
| const char kDelimiterSpaceChar = ' '; |
| |
| // https://tools.ietf.org/html/draft-ietf-mmusic-sdp-simulcast-13#section-5.1 |
| // https://tools.ietf.org/html/draft-ietf-mmusic-rid-15#section-10 |
| const char kSimulcastPausedStream[] = "~"; |
| const char kSimulcastPausedStreamChar = '~'; |
| const char kSendDirection[] = "send"; |
| const char kReceiveDirection[] = "recv"; |
| const char kPayloadType[] = "pt"; |
| |
| RTCError ParseError(absl::string_view message) { |
| return RTCError(RTCErrorType::SYNTAX_ERROR, message); |
| } |
| |
| // These methods serialize simulcast according to the specification: |
| // https://tools.ietf.org/html/draft-ietf-mmusic-sdp-simulcast-13#section-5.1 |
| StringBuilder& operator<<(StringBuilder& builder, |
| const SimulcastLayer& simulcast_layer) { |
| if (simulcast_layer.is_paused) { |
| builder << kSimulcastPausedStream; |
| } |
| builder << simulcast_layer.rid; |
| return builder; |
| } |
| |
| StringBuilder& operator<<( |
| StringBuilder& builder, |
| const std::vector<SimulcastLayer>& layer_alternatives) { |
| bool first = true; |
| for (const SimulcastLayer& rid : layer_alternatives) { |
| if (!first) { |
| builder << kDelimiterComma; |
| } |
| builder << rid; |
| first = false; |
| } |
| return builder; |
| } |
| |
| StringBuilder& operator<<(StringBuilder& builder, |
| const SimulcastLayerList& simulcast_layers) { |
| bool first = true; |
| for (const auto& alternatives : simulcast_layers) { |
| if (!first) { |
| builder << kDelimiterSemicolon; |
| } |
| builder << alternatives; |
| first = false; |
| } |
| return builder; |
| } |
| // This method deserializes simulcast according to the specification: |
| // https://tools.ietf.org/html/draft-ietf-mmusic-sdp-simulcast-13#section-5.1 |
| // sc-str-list = sc-alt-list *( ";" sc-alt-list ) |
| // sc-alt-list = sc-id *( "," sc-id ) |
| // sc-id-paused = "~" |
| // sc-id = [sc-id-paused] rid-id |
| // rid-id = 1*(alpha-numeric / "-" / "_") ; see: I-D.ietf-mmusic-rid |
| RTCErrorOr<SimulcastLayerList> ParseSimulcastLayerList(const std::string& str) { |
| std::vector<absl::string_view> tokens = split(str, kDelimiterSemicolonChar); |
| if (tokens.empty()) { |
| return ParseError("Layer list cannot be empty."); |
| } |
| |
| SimulcastLayerList result; |
| for (const absl::string_view& token : tokens) { |
| if (token.empty()) { |
| return ParseError("Simulcast alternative layer list is empty."); |
| } |
| |
| std::vector<absl::string_view> rid_tokens = |
| split(token, kDelimiterCommaChar); |
| |
| if (rid_tokens.empty()) { |
| return ParseError("Simulcast alternative layer list is malformed."); |
| } |
| |
| std::vector<SimulcastLayer> layers; |
| for (const absl::string_view& rid_token : rid_tokens) { |
| if (rid_token.empty() || rid_token == kSimulcastPausedStream) { |
| return ParseError("Rid must not be empty."); |
| } |
| |
| bool paused = rid_token[0] == kSimulcastPausedStreamChar; |
| absl::string_view rid = paused ? rid_token.substr(1) : rid_token; |
| layers.push_back(SimulcastLayer(rid, paused)); |
| } |
| |
| result.AddLayerWithAlternatives(layers); |
| } |
| |
| return std::move(result); |
| } |
| |
| webrtc::RTCError ParseRidPayloadList(const std::string& payload_list, |
| RidDescription* rid_description, |
| std::vector<int>* rid_payload_types) { |
| RTC_DCHECK(rid_description); |
| RTC_DCHECK(rid_payload_types); |
| // Check that the description doesn't have any payload types or restrictions. |
| // If the pt= field is specified, it must be first and must not repeat. |
| if (!rid_payload_types->empty()) { |
| return ParseError("Multiple pt= found in RID Description."); |
| } |
| if (!rid_description->restrictions.empty()) { |
| return ParseError("Payload list must appear first in the restrictions."); |
| } |
| |
| // If the pt= field is specified, it must have a value. |
| if (payload_list.empty()) { |
| return ParseError("Payload list must have at least one value."); |
| } |
| |
| // Tokenize the ',' delimited list |
| std::vector<std::string> string_payloads; |
| tokenize(payload_list, kDelimiterCommaChar, &string_payloads); |
| if (string_payloads.empty()) { |
| return ParseError("Payload list must have at least one value."); |
| } |
| |
| for (const std::string& payload_type : string_payloads) { |
| std::optional<int> value = StringToNumber<int>(payload_type); |
| if (!value.has_value()) { |
| return ParseError("Invalid payload type: " + payload_type); |
| } |
| |
| // Check if the value already appears in the payload list. |
| if (absl::c_linear_search(*rid_payload_types, value.value())) { |
| return ParseError("Duplicate payload type in list: " + payload_type); |
| } |
| rid_payload_types->push_back(value.value()); |
| } |
| |
| return RTCError::OK(); |
| } |
| |
| } // namespace |
| |
| std::string SimulcastSdpSerializer::SerializeSimulcastDescription( |
| const SimulcastDescription& simulcast) const { |
| StringBuilder sb; |
| std::string delimiter; |
| |
| if (!simulcast.send_layers().empty()) { |
| sb << kSendDirection << kDelimiterSpace << simulcast.send_layers(); |
| delimiter = kDelimiterSpace; |
| } |
| |
| if (!simulcast.receive_layers().empty()) { |
| sb << delimiter << kReceiveDirection << kDelimiterSpace |
| << simulcast.receive_layers(); |
| } |
| |
| return sb.Release(); |
| } |
| |
| // https://tools.ietf.org/html/draft-ietf-mmusic-sdp-simulcast-13#section-5.1 |
| // a:simulcast:<send> <streams> <recv> <streams> |
| // Formal Grammar |
| // sc-value = ( sc-send [SP sc-recv] ) / ( sc-recv [SP sc-send] ) |
| // sc-send = %s"send" SP sc-str-list |
| // sc-recv = %s"recv" SP sc-str-list |
| // sc-str-list = sc-alt-list *( ";" sc-alt-list ) |
| // sc-alt-list = sc-id *( "," sc-id ) |
| // sc-id-paused = "~" |
| // sc-id = [sc-id-paused] rid-id |
| // rid-id = 1*(alpha-numeric / "-" / "_") ; see: I-D.ietf-mmusic-rid |
| RTCErrorOr<SimulcastDescription> |
| SimulcastSdpSerializer::DeserializeSimulcastDescription( |
| absl::string_view string) const { |
| std::vector<std::string> tokens; |
| tokenize(std::string(string), kDelimiterSpaceChar, &tokens); |
| |
| if (tokens.size() != 2 && tokens.size() != 4) { |
| return ParseError("Must have one or two <direction, streams> pairs."); |
| } |
| |
| bool bidirectional = tokens.size() == 4; // indicates both send and recv |
| |
| // Tokens 0, 2 (if exists) should be send / recv |
| if ((tokens[0] != kSendDirection && tokens[0] != kReceiveDirection) || |
| (bidirectional && tokens[2] != kSendDirection && |
| tokens[2] != kReceiveDirection) || |
| (bidirectional && tokens[0] == tokens[2])) { |
| return ParseError("Valid values: send / recv."); |
| } |
| |
| // Tokens 1, 3 (if exists) should be alternative layer lists |
| RTCErrorOr<SimulcastLayerList> list1, list2; |
| list1 = ParseSimulcastLayerList(tokens[1]); |
| if (!list1.ok()) { |
| return list1.MoveError(); |
| } |
| |
| if (bidirectional) { |
| list2 = ParseSimulcastLayerList(tokens[3]); |
| if (!list2.ok()) { |
| return list2.MoveError(); |
| } |
| } |
| |
| // Set the layers so that list1 is for send and list2 is for recv |
| if (tokens[0] != kSendDirection) { |
| std::swap(list1, list2); |
| } |
| |
| // Set the layers according to which pair is send and which is recv |
| // At this point if the simulcast is unidirectional then |
| // either `list1` or `list2` will be in 'error' state indicating that |
| // the value should not be used. |
| SimulcastDescription simulcast; |
| if (list1.ok()) { |
| simulcast.send_layers() = list1.MoveValue(); |
| } |
| |
| if (list2.ok()) { |
| simulcast.receive_layers() = list2.MoveValue(); |
| } |
| |
| return std::move(simulcast); |
| } |
| |
| std::string SimulcastSdpSerializer::SerializeRidDescription( |
| const MediaContentDescription& media_desc, |
| const RidDescription& rid_description) const { |
| RTC_DCHECK(!rid_description.rid.empty()); |
| RTC_DCHECK(rid_description.direction == RidDirection::kSend || |
| rid_description.direction == RidDirection::kReceive); |
| |
| StringBuilder builder; |
| builder << rid_description.rid << kDelimiterSpace |
| << (rid_description.direction == RidDirection::kSend |
| ? kSendDirection |
| : kReceiveDirection); |
| |
| // Convert `rid_descriptions.codecs` into a list of payload types based on |
| // looking up codecs from the media description, as opposed to trusting the |
| // `rid_descriptions.codecs[i].id` directly as these are typically wrong. |
| std::vector<int> payload_types; |
| for (const Codec& codec : rid_description.codecs) { |
| RtpCodec rtp_codec = codec.ToCodecParameters(); |
| const auto it = std::find_if( |
| media_desc.codecs().begin(), media_desc.codecs().end(), |
| [&rtp_codec](const Codec& m_section_codec) { |
| return IsSameRtpCodecIgnoringLevel(m_section_codec, rtp_codec); |
| }); |
| // The desired codec from setParameters() may not have been negotiated, e.g. |
| // if excluded with setCodecPreferences(). |
| if (it == media_desc.codecs().end()) { |
| break; |
| } |
| if (it->id == Codec::kIdNotSet) { |
| RTC_DCHECK_NOTREACHED(); |
| break; |
| } |
| payload_types.push_back(it->id); |
| } |
| |
| const auto& restrictions = rid_description.restrictions; |
| |
| // First property is separated by ' ', the next ones by ';'. |
| const char* propertyDelimiter = kDelimiterSpace; |
| |
| // Serialize any codecs in the description. |
| if (!payload_types.empty()) { |
| builder << propertyDelimiter << kPayloadType << kDelimiterEqual; |
| propertyDelimiter = kDelimiterSemicolon; |
| const char* formatDelimiter = ""; |
| for (int payload_type : payload_types) { |
| builder << formatDelimiter << payload_type; |
| formatDelimiter = kDelimiterComma; |
| } |
| } |
| |
| // Serialize any restrictions in the description. |
| for (const auto& pair : restrictions) { |
| // Serialize key=val pairs. =val part is ommitted if val is empty. |
| builder << propertyDelimiter << pair.first; |
| if (!pair.second.empty()) { |
| builder << kDelimiterEqual << pair.second; |
| } |
| |
| propertyDelimiter = kDelimiterSemicolon; |
| } |
| |
| return builder.Release(); |
| } |
| |
| // https://tools.ietf.org/html/draft-ietf-mmusic-rid-15#section-10 |
| // Formal Grammar |
| // rid-syntax = %s"a=rid:" rid-id SP rid-dir |
| // [ rid-pt-param-list / rid-param-list ] |
| // rid-id = 1*(alpha-numeric / "-" / "_") |
| // rid-dir = %s"send" / %s"recv" |
| // rid-pt-param-list = SP rid-fmt-list *( ";" rid-param ) |
| // rid-param-list = SP rid-param *( ";" rid-param ) |
| // rid-fmt-list = %s"pt=" fmt *( "," fmt ) |
| // rid-param = 1*(alpha-numeric / "-") [ "=" param-val ] |
| // param-val = *( %x20-58 / %x60-7E ) |
| // ; Any printable character except semicolon |
| RTCErrorOr<RidDescription> SimulcastSdpSerializer::DeserializeRidDescription( |
| const MediaContentDescription& media_desc, |
| absl::string_view string) const { |
| std::vector<std::string> tokens; |
| tokenize(std::string(string), kDelimiterSpaceChar, &tokens); |
| |
| if (tokens.size() < 2) { |
| return ParseError("RID Description must contain <RID> <direction>."); |
| } |
| |
| if (tokens.size() > 3) { |
| return ParseError("Invalid RID Description format. Too many arguments."); |
| } |
| |
| if (!IsLegalRsidName(tokens[0])) { |
| return ParseError("Invalid RID value: " + tokens[0] + "."); |
| } |
| |
| if (tokens[1] != kSendDirection && tokens[1] != kReceiveDirection) { |
| return ParseError("Invalid RID direction. Supported values: send / recv."); |
| } |
| |
| RidDirection direction = tokens[1] == kSendDirection ? RidDirection::kSend |
| : RidDirection::kReceive; |
| |
| RidDescription rid_description(tokens[0], direction); |
| std::vector<int> rid_payload_types; |
| |
| // If there is a third argument it is a payload list and/or restriction list. |
| if (tokens.size() == 3) { |
| std::vector<std::string> restrictions; |
| tokenize(tokens[2], kDelimiterSemicolonChar, &restrictions); |
| |
| // Check for malformed restriction list, such as ';' or ';;;' etc. |
| if (restrictions.empty()) { |
| return ParseError("Invalid RID restriction list: " + tokens[2]); |
| } |
| |
| // Parse the restrictions. The payload indicator (pt) can only appear first. |
| for (const std::string& restriction : restrictions) { |
| std::vector<std::string> parts; |
| tokenize(restriction, kDelimiterEqualChar, &parts); |
| if (parts.empty() || parts.size() > 2) { |
| return ParseError("Invalid format for restriction: " + restriction); |
| } |
| |
| // `parts` contains at least one value and it does not contain a space. |
| // Note: `parts` and other values might still contain tab, newline, |
| // unprintable characters, etc. which will not generate errors here but |
| // will (most-likely) be ignored by components down stream. |
| if (parts[0] == kPayloadType) { |
| RTCError error = |
| ParseRidPayloadList(parts.size() > 1 ? parts[1] : std::string(), |
| &rid_description, &rid_payload_types); |
| if (!error.ok()) { |
| return std::move(error); |
| } |
| |
| continue; |
| } |
| |
| // Parse `parts` as a key=value pair which allows unspecified values. |
| if (rid_description.restrictions.find(parts[0]) != |
| rid_description.restrictions.end()) { |
| return ParseError("Duplicate restriction specified: " + parts[0]); |
| } |
| |
| rid_description.restrictions[parts[0]] = |
| parts.size() > 1 ? parts[1] : std::string(); |
| } |
| } |
| |
| // Look up any referenced codecs from the media section and add them to |
| // `rid_description.codecs`. |
| for (const int& payload_type : rid_payload_types) { |
| const auto it = |
| std::find_if(media_desc.codecs().begin(), media_desc.codecs().end(), |
| [&payload_type](const Codec& m_section_codec) { |
| return m_section_codec.id == payload_type; |
| }); |
| if (it == media_desc.codecs().end()) { |
| // This RID has a payload type that doesn't map to any known codec. While |
| // this is an error on the part of the entity that generated the SDP, this |
| // information falls into the "FYI" category and does not really change |
| // anything, so it's safe to ignore it. |
| RTC_LOG(LS_WARNING) << "A RID contains an unknown payload type."; |
| continue; |
| } |
| rid_description.codecs.push_back(*it); |
| } |
| |
| return std::move(rid_description); |
| } |
| |
| } // namespace webrtc |