blob: 96be3b223f59fb25a59334d35b5a1aa51c4036fa [file] [log] [blame]
/*
* Copyright 2011 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/webrtc_sdp.h"
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
#include <algorithm>
#include <map>
#include <memory>
#include <set>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
#include "absl/algorithm/container.h"
#include "absl/memory/memory.h"
#include "absl/strings/match.h"
#include "api/candidate.h"
#include "api/crypto_params.h"
#include "api/jsep_ice_candidate.h"
#include "api/jsep_session_description.h"
#include "api/media_types.h"
// for RtpExtension
#include "api/rtp_parameters.h"
#include "media/base/codec.h"
#include "media/base/media_constants.h"
#include "media/base/rtp_utils.h"
#include "media/sctp/sctp_transport_internal.h"
#include "p2p/base/p2p_constants.h"
#include "p2p/base/port.h"
#include "pc/media_session.h"
#include "pc/sdp_serializer.h"
#include "rtc_base/arraysize.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/message_digest.h"
#include "rtc_base/string_utils.h"
#include "rtc_base/strings/string_builder.h"
#include "rtc_base/third_party/base64/base64.h"
using cricket::AudioContentDescription;
using cricket::Candidate;
using cricket::Candidates;
using cricket::ContentInfo;
using cricket::CryptoParams;
using cricket::DataContentDescription;
using cricket::ICE_CANDIDATE_COMPONENT_RTCP;
using cricket::ICE_CANDIDATE_COMPONENT_RTP;
using cricket::kCodecParamAssociatedPayloadType;
using cricket::kCodecParamMaxAverageBitrate;
using cricket::kCodecParamMaxBitrate;
using cricket::kCodecParamMaxPlaybackRate;
using cricket::kCodecParamMaxPTime;
using cricket::kCodecParamMaxQuantization;
using cricket::kCodecParamMinBitrate;
using cricket::kCodecParamMinPTime;
using cricket::kCodecParamPTime;
using cricket::kCodecParamSctpProtocol;
using cricket::kCodecParamSctpStreams;
using cricket::kCodecParamSPropStereo;
using cricket::kCodecParamStartBitrate;
using cricket::kCodecParamStereo;
using cricket::kCodecParamUseDtx;
using cricket::kCodecParamUseInbandFec;
using cricket::MediaContentDescription;
using cricket::MediaProtocolType;
using cricket::MediaType;
using cricket::RidDescription;
using cricket::RtpDataContentDescription;
using cricket::RtpHeaderExtensions;
using cricket::SctpDataContentDescription;
using cricket::SimulcastDescription;
using cricket::SimulcastLayer;
using cricket::SimulcastLayerList;
using cricket::SsrcGroup;
using cricket::StreamParams;
using cricket::StreamParamsVec;
using cricket::TransportDescription;
using cricket::TransportInfo;
using cricket::VideoContentDescription;
using rtc::SocketAddress;
namespace cricket {
class SessionDescription;
}
// TODO(deadbeef): Switch to using anonymous namespace rather than declaring
// everything "static".
namespace webrtc {
// Line type
// RFC 4566
// An SDP session description consists of a number of lines of text of
// the form:
// <type>=<value>
// where <type> MUST be exactly one case-significant character.
static const int kLinePrefixLength = 2; // Length of <type>=
static const char kLineTypeVersion = 'v';
static const char kLineTypeOrigin = 'o';
static const char kLineTypeSessionName = 's';
static const char kLineTypeSessionInfo = 'i';
static const char kLineTypeSessionUri = 'u';
static const char kLineTypeSessionEmail = 'e';
static const char kLineTypeSessionPhone = 'p';
static const char kLineTypeSessionBandwidth = 'b';
static const char kLineTypeTiming = 't';
static const char kLineTypeRepeatTimes = 'r';
static const char kLineTypeTimeZone = 'z';
static const char kLineTypeEncryptionKey = 'k';
static const char kLineTypeMedia = 'm';
static const char kLineTypeConnection = 'c';
static const char kLineTypeAttributes = 'a';
// Attributes
static const char kAttributeGroup[] = "group";
static const char kAttributeMid[] = "mid";
static const char kAttributeMsid[] = "msid";
static const char kAttributeBundleOnly[] = "bundle-only";
static const char kAttributeRtcpMux[] = "rtcp-mux";
static const char kAttributeRtcpReducedSize[] = "rtcp-rsize";
static const char kAttributeSsrc[] = "ssrc";
static const char kSsrcAttributeCname[] = "cname";
static const char kAttributeExtmapAllowMixed[] = "extmap-allow-mixed";
static const char kAttributeExtmap[] = "extmap";
// draft-alvestrand-mmusic-msid-01
// a=msid-semantic: WMS
// This is a legacy field supported only for Plan B semantics.
static const char kAttributeMsidSemantics[] = "msid-semantic";
static const char kMediaStreamSemantic[] = "WMS";
static const char kSsrcAttributeMsid[] = "msid";
static const char kDefaultMsid[] = "default";
static const char kNoStreamMsid[] = "-";
static const char kSsrcAttributeMslabel[] = "mslabel";
static const char kSSrcAttributeLabel[] = "label";
static const char kAttributeSsrcGroup[] = "ssrc-group";
static const char kAttributeCrypto[] = "crypto";
static const char kAttributeCandidate[] = "candidate";
static const char kAttributeCandidateTyp[] = "typ";
static const char kAttributeCandidateRaddr[] = "raddr";
static const char kAttributeCandidateRport[] = "rport";
static const char kAttributeCandidateUfrag[] = "ufrag";
static const char kAttributeCandidatePwd[] = "pwd";
static const char kAttributeCandidateGeneration[] = "generation";
static const char kAttributeCandidateNetworkId[] = "network-id";
static const char kAttributeCandidateNetworkCost[] = "network-cost";
static const char kAttributeFingerprint[] = "fingerprint";
static const char kAttributeSetup[] = "setup";
static const char kAttributeFmtp[] = "fmtp";
static const char kAttributeRtpmap[] = "rtpmap";
static const char kAttributeSctpmap[] = "sctpmap";
static const char kAttributeRtcp[] = "rtcp";
static const char kAttributeIceUfrag[] = "ice-ufrag";
static const char kAttributeIcePwd[] = "ice-pwd";
static const char kAttributeIceLite[] = "ice-lite";
static const char kAttributeIceOption[] = "ice-options";
static const char kAttributeSendOnly[] = "sendonly";
static const char kAttributeRecvOnly[] = "recvonly";
static const char kAttributeRtcpFb[] = "rtcp-fb";
static const char kAttributeSendRecv[] = "sendrecv";
static const char kAttributeInactive[] = "inactive";
// draft-ietf-mmusic-sctp-sdp-26
// a=sctp-port, a=max-message-size
static const char kAttributeSctpPort[] = "sctp-port";
static const char kAttributeMaxMessageSize[] = "max-message-size";
static const int kDefaultSctpMaxMessageSize = 65536;
// draft-ietf-mmusic-sdp-simulcast-13
// a=simulcast
static const char kAttributeSimulcast[] = "simulcast";
// draft-ietf-mmusic-rid-15
// a=rid
static const char kAttributeRid[] = "rid";
// Experimental flags
static const char kAttributeXGoogleFlag[] = "x-google-flag";
static const char kValueConference[] = "conference";
// Candidate
static const char kCandidateHost[] = "host";
static const char kCandidateSrflx[] = "srflx";
static const char kCandidatePrflx[] = "prflx";
static const char kCandidateRelay[] = "relay";
static const char kTcpCandidateType[] = "tcptype";
// rtc::StringBuilder doesn't have a << overload for chars, while rtc::split and
// rtc::tokenize_first both take a char delimiter. To handle both cases these
// constants come in pairs of a chars and length-one strings.
static const char kSdpDelimiterEqual[] = "=";
static const char kSdpDelimiterEqualChar = '=';
static const char kSdpDelimiterSpace[] = " ";
static const char kSdpDelimiterSpaceChar = ' ';
static const char kSdpDelimiterColon[] = ":";
static const char kSdpDelimiterColonChar = ':';
static const char kSdpDelimiterSemicolon[] = ";";
static const char kSdpDelimiterSemicolonChar = ';';
static const char kSdpDelimiterSlashChar = '/';
static const char kNewLine[] = "\n";
static const char kNewLineChar = '\n';
static const char kReturnChar = '\r';
static const char kLineBreak[] = "\r\n";
// TODO(deadbeef): Generate the Session and Time description
// instead of hardcoding.
static const char kSessionVersion[] = "v=0";
// RFC 4566
static const char kSessionOriginUsername[] = "-";
static const char kSessionOriginSessionId[] = "0";
static const char kSessionOriginSessionVersion[] = "0";
static const char kSessionOriginNettype[] = "IN";
static const char kSessionOriginAddrtype[] = "IP4";
static const char kSessionOriginAddress[] = "127.0.0.1";
static const char kSessionName[] = "s=-";
static const char kTimeDescription[] = "t=0 0";
static const char kAttrGroup[] = "a=group:BUNDLE";
static const char kConnectionNettype[] = "IN";
static const char kConnectionIpv4Addrtype[] = "IP4";
static const char kConnectionIpv6Addrtype[] = "IP6";
static const char kMediaTypeVideo[] = "video";
static const char kMediaTypeAudio[] = "audio";
static const char kMediaTypeData[] = "application";
static const char kMediaPortRejected[] = "0";
// draft-ietf-mmusic-trickle-ice-01
// When no candidates have been gathered, set the connection
// address to IP6 ::.
// TODO(perkj): FF can not parse IP6 ::. See http://crbug/430333
// Use IPV4 per default.
static const char kDummyAddress[] = "0.0.0.0";
static const char kDummyPort[] = "9";
// RFC 3556
static const char kApplicationSpecificMaximum[] = "AS";
static const char kDefaultSctpmapProtocol[] = "webrtc-datachannel";
// This is a non-standardized media transport settings.
// This setting is going to be set in the offer. There may be one or more
// a=x-mt: settings, and they are in the priority order (the most preferred on
// top). x-mt setting format depends on the media transport, and is generated by
// |MediaTransportInterface::GetTransportParametersOffer|.
static const char kMediaTransportSettingLine[] = "x-mt";
// RTP payload type is in the 0-127 range. Use -1 to indicate "all" payload
// types.
const int kWildcardPayloadType = -1;
struct SsrcInfo {
uint32_t ssrc_id;
std::string cname;
std::string stream_id;
std::string track_id;
// For backward compatibility.
// TODO(ronghuawu): Remove below 2 fields once all the clients support msid.
std::string label;
std::string mslabel;
};
typedef std::vector<SsrcInfo> SsrcInfoVec;
typedef std::vector<SsrcGroup> SsrcGroupVec;
template <class T>
static void AddFmtpLine(const T& codec, std::string* message);
static void BuildMediaDescription(const ContentInfo* content_info,
const TransportInfo* transport_info,
const cricket::MediaType media_type,
const std::vector<Candidate>& candidates,
int msid_signaling,
std::string* message);
static void BuildRtpContentAttributes(const MediaContentDescription* media_desc,
const cricket::MediaType media_type,
int msid_signaling,
std::string* message);
static void BuildRtpMap(const MediaContentDescription* media_desc,
const cricket::MediaType media_type,
std::string* message);
static void BuildCandidate(const std::vector<Candidate>& candidates,
bool include_ufrag,
std::string* message);
static void BuildIceOptions(const std::vector<std::string>& transport_options,
std::string* message);
static bool ParseSessionDescription(const std::string& message,
size_t* pos,
std::string* session_id,
std::string* session_version,
TransportDescription* session_td,
RtpHeaderExtensions* session_extmaps,
rtc::SocketAddress* connection_addr,
cricket::SessionDescription* desc,
SdpParseError* error);
static bool ParseGroupAttribute(const std::string& line,
cricket::SessionDescription* desc,
SdpParseError* error);
static bool ParseMediaDescription(
const std::string& message,
const TransportDescription& session_td,
const RtpHeaderExtensions& session_extmaps,
size_t* pos,
const rtc::SocketAddress& session_connection_addr,
cricket::SessionDescription* desc,
std::vector<std::unique_ptr<JsepIceCandidate>>* candidates,
SdpParseError* error);
static bool ParseContent(
const std::string& message,
const cricket::MediaType media_type,
int mline_index,
const std::string& protocol,
const std::vector<int>& payload_types,
size_t* pos,
std::string* content_name,
bool* bundle_only,
int* msid_signaling,
MediaContentDescription* media_desc,
TransportDescription* transport,
std::vector<std::unique_ptr<JsepIceCandidate>>* candidates,
SdpParseError* error);
static bool ParseSsrcAttribute(const std::string& line,
SsrcInfoVec* ssrc_infos,
int* msid_signaling,
SdpParseError* error);
static bool ParseSsrcGroupAttribute(const std::string& line,
SsrcGroupVec* ssrc_groups,
SdpParseError* error);
static bool ParseCryptoAttribute(const std::string& line,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseRtpmapAttribute(const std::string& line,
const cricket::MediaType media_type,
const std::vector<int>& payload_types,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseFmtpAttributes(const std::string& line,
const cricket::MediaType media_type,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseFmtpParam(const std::string& line,
std::string* parameter,
std::string* value,
SdpParseError* error);
static bool ParseRtcpFbAttribute(const std::string& line,
const cricket::MediaType media_type,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseIceOptions(const std::string& line,
std::vector<std::string>* transport_options,
SdpParseError* error);
static bool ParseExtmap(const std::string& line,
RtpExtension* extmap,
SdpParseError* error);
static bool ParseFingerprintAttribute(
const std::string& line,
std::unique_ptr<rtc::SSLFingerprint>* fingerprint,
SdpParseError* error);
static bool ParseDtlsSetup(const std::string& line,
cricket::ConnectionRole* role,
SdpParseError* error);
static bool ParseMsidAttribute(const std::string& line,
std::vector<std::string>* stream_ids,
std::string* track_id,
SdpParseError* error);
static void RemoveInvalidRidDescriptions(const std::vector<int>& payload_types,
std::vector<RidDescription>* rids);
static SimulcastLayerList RemoveRidsFromSimulcastLayerList(
const std::set<std::string>& to_remove,
const SimulcastLayerList& layers);
static void RemoveInvalidRidsFromSimulcast(
const std::vector<RidDescription>& rids,
SimulcastDescription* simulcast);
// Helper functions
// Below ParseFailed*** functions output the line that caused the parsing
// failure and the detailed reason (|description|) of the failure to |error|.
// The functions always return false so that they can be used directly in the
// following way when error happens:
// "return ParseFailed***(...);"
// The line starting at |line_start| of |message| is the failing line.
// The reason for the failure should be provided in the |description|.
// An example of a description could be "unknown character".
static bool ParseFailed(const std::string& message,
size_t line_start,
const std::string& description,
SdpParseError* error) {
// Get the first line of |message| from |line_start|.
std::string first_line;
size_t line_end = message.find(kNewLine, line_start);
if (line_end != std::string::npos) {
if (line_end > 0 && (message.at(line_end - 1) == kReturnChar)) {
--line_end;
}
first_line = message.substr(line_start, (line_end - line_start));
} else {
first_line = message.substr(line_start);
}
if (error) {
error->line = first_line;
error->description = description;
}
RTC_LOG(LS_ERROR) << "Failed to parse: \"" << first_line
<< "\". Reason: " << description;
return false;
}
// |line| is the failing line. The reason for the failure should be
// provided in the |description|.
static bool ParseFailed(const std::string& line,
const std::string& description,
SdpParseError* error) {
return ParseFailed(line, 0, description, error);
}
// Parses failure where the failing SDP line isn't know or there are multiple
// failing lines.
static bool ParseFailed(const std::string& description, SdpParseError* error) {
return ParseFailed("", description, error);
}
// |line| is the failing line. The failure is due to the fact that |line|
// doesn't have |expected_fields| fields.
static bool ParseFailedExpectFieldNum(const std::string& line,
int expected_fields,
SdpParseError* error) {
rtc::StringBuilder description;
description << "Expects " << expected_fields << " fields.";
return ParseFailed(line, description.str(), error);
}
// |line| is the failing line. The failure is due to the fact that |line| has
// less than |expected_min_fields| fields.
static bool ParseFailedExpectMinFieldNum(const std::string& line,
int expected_min_fields,
SdpParseError* error) {
rtc::StringBuilder description;
description << "Expects at least " << expected_min_fields << " fields.";
return ParseFailed(line, description.str(), error);
}
// |line| is the failing line. The failure is due to the fact that it failed to
// get the value of |attribute|.
static bool ParseFailedGetValue(const std::string& line,
const std::string& attribute,
SdpParseError* error) {
rtc::StringBuilder description;
description << "Failed to get the value of attribute: " << attribute;
return ParseFailed(line, description.str(), error);
}
// The line starting at |line_start| of |message| is the failing line. The
// failure is due to the line type (e.g. the "m" part of the "m-line")
// not matching what is expected. The expected line type should be
// provided as |line_type|.
static bool ParseFailedExpectLine(const std::string& message,
size_t line_start,
const char line_type,
const std::string& line_value,
SdpParseError* error) {
rtc::StringBuilder description;
description << "Expect line: " << std::string(1, line_type) << "="
<< line_value;
return ParseFailed(message, line_start, description.str(), error);
}
static bool AddLine(const std::string& line, std::string* message) {
if (!message)
return false;
message->append(line);
message->append(kLineBreak);
return true;
}
static bool GetLine(const std::string& message,
size_t* pos,
std::string* line) {
size_t line_begin = *pos;
size_t line_end = message.find(kNewLine, line_begin);
if (line_end == std::string::npos) {
return false;
}
// Update the new start position
*pos = line_end + 1;
if (line_end > 0 && (message.at(line_end - 1) == kReturnChar)) {
--line_end;
}
*line = message.substr(line_begin, (line_end - line_begin));
const char* cline = line->c_str();
// RFC 4566
// An SDP session description consists of a number of lines of text of
// the form:
// <type>=<value>
// where <type> MUST be exactly one case-significant character and
// <value> is structured text whose format depends on <type>.
// Whitespace MUST NOT be used on either side of the "=" sign.
//
// However, an exception to the whitespace rule is made for "s=", since
// RFC4566 also says:
//
// If a session has no meaningful name, the value "s= " SHOULD be used
// (i.e., a single space as the session name).
if (line->length() < 3 || !islower(cline[0]) ||
cline[1] != kSdpDelimiterEqualChar ||
(cline[0] != kLineTypeSessionName &&
cline[2] == kSdpDelimiterSpaceChar)) {
*pos = line_begin;
return false;
}
return true;
}
// Init |os| to "|type|=|value|".
static void InitLine(const char type,
const std::string& value,
rtc::StringBuilder* os) {
os->Clear();
*os << std::string(1, type) << kSdpDelimiterEqual << value;
}
// Init |os| to "a=|attribute|".
static void InitAttrLine(const std::string& attribute, rtc::StringBuilder* os) {
InitLine(kLineTypeAttributes, attribute, os);
}
// Writes an x-mt SDP attribute line based on the media transport settings.
static void AddMediaTransportLine(
const cricket::SessionDescription::MediaTransportSetting& setting,
std::string* message) {
rtc::StringBuilder os;
InitAttrLine(kMediaTransportSettingLine, &os);
os << kSdpDelimiterColon << setting.transport_name << kSdpDelimiterColon
<< rtc::Base64::Encode(setting.transport_setting);
AddLine(os.str(), message);
}
// Writes a SDP attribute line based on |attribute| and |value| to |message|.
static void AddAttributeLine(const std::string& attribute,
int value,
std::string* message) {
rtc::StringBuilder os;
InitAttrLine(attribute, &os);
os << kSdpDelimiterColon << value;
AddLine(os.str(), message);
}
static bool IsLineType(const std::string& message,
const char type,
size_t line_start) {
if (message.size() < line_start + kLinePrefixLength) {
return false;
}
const char* cmessage = message.c_str();
return (cmessage[line_start] == type &&
cmessage[line_start + 1] == kSdpDelimiterEqualChar);
}
static bool IsLineType(const std::string& line, const char type) {
return IsLineType(line, type, 0);
}
static bool GetLineWithType(const std::string& message,
size_t* pos,
std::string* line,
const char type) {
if (!IsLineType(message, type, *pos)) {
return false;
}
if (!GetLine(message, pos, line))
return false;
return true;
}
static bool HasAttribute(const std::string& line,
const std::string& attribute) {
if (line.compare(kLinePrefixLength, attribute.size(), attribute) == 0) {
// Make sure that the match is not only a partial match. If length of
// strings doesn't match, the next character of the line must be ':' or ' '.
// This function is also used for media descriptions (e.g., "m=audio 9..."),
// hence the need to also allow space in the end.
RTC_CHECK_LE(kLinePrefixLength + attribute.size(), line.size());
if ((kLinePrefixLength + attribute.size()) == line.size() ||
line[kLinePrefixLength + attribute.size()] == kSdpDelimiterColonChar ||
line[kLinePrefixLength + attribute.size()] == kSdpDelimiterSpaceChar) {
return true;
}
}
return false;
}
static bool AddSsrcLine(uint32_t ssrc_id,
const std::string& attribute,
const std::string& value,
std::string* message) {
// RFC 5576
// a=ssrc:<ssrc-id> <attribute>:<value>
rtc::StringBuilder os;
InitAttrLine(kAttributeSsrc, &os);
os << kSdpDelimiterColon << ssrc_id << kSdpDelimiterSpace << attribute
<< kSdpDelimiterColon << value;
return AddLine(os.str(), message);
}
// Get value only from <attribute>:<value>.
static bool GetValue(const std::string& message,
const std::string& attribute,
std::string* value,
SdpParseError* error) {
std::string leftpart;
if (!rtc::tokenize_first(message, kSdpDelimiterColonChar, &leftpart, value)) {
return ParseFailedGetValue(message, attribute, error);
}
// The left part should end with the expected attribute.
if (leftpart.length() < attribute.length() ||
leftpart.compare(leftpart.length() - attribute.length(),
attribute.length(), attribute) != 0) {
return ParseFailedGetValue(message, attribute, error);
}
return true;
}
static bool CaseInsensitiveFind(std::string str1, std::string str2) {
absl::c_transform(str1, str1.begin(), ::tolower);
absl::c_transform(str2, str2.begin(), ::tolower);
return str1.find(str2) != std::string::npos;
}
template <class T>
static bool GetValueFromString(const std::string& line,
const std::string& s,
T* t,
SdpParseError* error) {
if (!rtc::FromString(s, t)) {
rtc::StringBuilder description;
description << "Invalid value: " << s << ".";
return ParseFailed(line, description.str(), error);
}
return true;
}
static bool GetPayloadTypeFromString(const std::string& line,
const std::string& s,
int* payload_type,
SdpParseError* error) {
return GetValueFromString(line, s, payload_type, error) &&
cricket::IsValidRtpPayloadType(*payload_type);
}
// Creates a StreamParams track in the case when no SSRC lines are signaled.
// This is a track that does not contain SSRCs and only contains
// stream_ids/track_id if it's signaled with a=msid lines.
void CreateTrackWithNoSsrcs(const std::vector<std::string>& msid_stream_ids,
const std::string& msid_track_id,
const std::vector<RidDescription>& rids,
StreamParamsVec* tracks) {
StreamParams track;
if (msid_track_id.empty() && rids.empty()) {
// We only create an unsignaled track if a=msid lines were signaled.
RTC_LOG(LS_INFO) << "MSID not signaled, skipping creation of StreamParams";
return;
}
track.set_stream_ids(msid_stream_ids);
track.id = msid_track_id;
track.set_rids(rids);
tracks->push_back(track);
}
// Creates the StreamParams tracks, for the case when SSRC lines are signaled.
// |msid_stream_ids| and |msid_track_id| represent the stream/track ID from the
// "a=msid" attribute, if it exists. They are empty if the attribute does not
// exist. We prioritize getting stream_ids/track_ids signaled in a=msid lines.
void CreateTracksFromSsrcInfos(const SsrcInfoVec& ssrc_infos,
const std::vector<std::string>& msid_stream_ids,
const std::string& msid_track_id,
StreamParamsVec* tracks,
int msid_signaling) {
RTC_DCHECK(tracks != NULL);
for (const SsrcInfo& ssrc_info : ssrc_infos) {
if (ssrc_info.cname.empty()) {
continue;
}
std::vector<std::string> stream_ids;
std::string track_id;
if (msid_signaling & cricket::kMsidSignalingMediaSection) {
// This is the case with Unified Plan SDP msid signaling.
stream_ids = msid_stream_ids;
track_id = msid_track_id;
} else if (msid_signaling & cricket::kMsidSignalingSsrcAttribute) {
// This is the case with Plan B SDP msid signaling.
stream_ids.push_back(ssrc_info.stream_id);
track_id = ssrc_info.track_id;
} else if (!ssrc_info.mslabel.empty()) {
// Since there's no a=msid or a=ssrc msid signaling, this is a sdp from
// an older version of client that doesn't support msid.
// In that case, we use the mslabel and label to construct the track.
stream_ids.push_back(ssrc_info.mslabel);
track_id = ssrc_info.label;
} else {
// Since no media streams isn't supported with older SDP signaling, we
// use a default a stream id.
stream_ids.push_back(kDefaultMsid);
}
// If a track ID wasn't populated from the SSRC attributes OR the
// msid attribute, use default/random values.
if (track_id.empty()) {
// TODO(ronghuawu): What should we do if the track id doesn't appear?
// Create random string (which will be used as track label later)?
track_id = rtc::CreateRandomString(8);
}
auto track_it = absl::c_find_if(
*tracks,
[track_id](const StreamParams& track) { return track.id == track_id; });
if (track_it == tracks->end()) {
// If we don't find an existing track, create a new one.
tracks->push_back(StreamParams());
track_it = tracks->end() - 1;
}
StreamParams& track = *track_it;
track.add_ssrc(ssrc_info.ssrc_id);
track.cname = ssrc_info.cname;
track.set_stream_ids(stream_ids);
track.id = track_id;
}
}
void GetMediaStreamIds(const ContentInfo* content,
std::set<std::string>* labels) {
for (const StreamParams& stream_params :
content->media_description()->streams()) {
for (const std::string& stream_id : stream_params.stream_ids()) {
labels->insert(stream_id);
}
}
}
// RFC 5245
// It is RECOMMENDED that default candidates be chosen based on the
// likelihood of those candidates to work with the peer that is being
// contacted. It is RECOMMENDED that relayed > reflexive > host.
static const int kPreferenceUnknown = 0;
static const int kPreferenceHost = 1;
static const int kPreferenceReflexive = 2;
static const int kPreferenceRelayed = 3;
static int GetCandidatePreferenceFromType(const std::string& type) {
int preference = kPreferenceUnknown;
if (type == cricket::LOCAL_PORT_TYPE) {
preference = kPreferenceHost;
} else if (type == cricket::STUN_PORT_TYPE) {
preference = kPreferenceReflexive;
} else if (type == cricket::RELAY_PORT_TYPE) {
preference = kPreferenceRelayed;
} else {
RTC_NOTREACHED();
}
return preference;
}
// Get ip and port of the default destination from the |candidates| with the
// given value of |component_id|. The default candidate should be the one most
// likely to work, typically IPv4 relay.
// RFC 5245
// The value of |component_id| currently supported are 1 (RTP) and 2 (RTCP).
// TODO(deadbeef): Decide the default destination in webrtcsession and
// pass it down via SessionDescription.
static void GetDefaultDestination(const std::vector<Candidate>& candidates,
int component_id,
std::string* port,
std::string* ip,
std::string* addr_type) {
*addr_type = kConnectionIpv4Addrtype;
*port = kDummyPort;
*ip = kDummyAddress;
int current_preference = kPreferenceUnknown;
int current_family = AF_UNSPEC;
for (const Candidate& candidate : candidates) {
if (candidate.component() != component_id) {
continue;
}
// Default destination should be UDP only.
if (candidate.protocol() != cricket::UDP_PROTOCOL_NAME) {
continue;
}
const int preference = GetCandidatePreferenceFromType(candidate.type());
const int family = candidate.address().ipaddr().family();
// See if this candidate is more preferable then the current one if it's the
// same family. Or if the current family is IPv4 already so we could safely
// ignore all IPv6 ones. WebRTC bug 4269.
// http://code.google.com/p/webrtc/issues/detail?id=4269
if ((preference <= current_preference && current_family == family) ||
(current_family == AF_INET && family == AF_INET6)) {
continue;
}
if (family == AF_INET) {
addr_type->assign(kConnectionIpv4Addrtype);
} else if (family == AF_INET6) {
addr_type->assign(kConnectionIpv6Addrtype);
}
current_preference = preference;
current_family = family;
*port = candidate.address().PortAsString();
*ip = candidate.address().ipaddr().ToString();
}
}
// Gets "a=rtcp" line if found default RTCP candidate from |candidates|.
static std::string GetRtcpLine(const std::vector<Candidate>& candidates) {
std::string rtcp_line, rtcp_port, rtcp_ip, addr_type;
GetDefaultDestination(candidates, ICE_CANDIDATE_COMPONENT_RTCP, &rtcp_port,
&rtcp_ip, &addr_type);
// Found default RTCP candidate.
// RFC 5245
// If the agent is utilizing RTCP, it MUST encode the RTCP candidate
// using the a=rtcp attribute as defined in RFC 3605.
// RFC 3605
// rtcp-attribute = "a=rtcp:" port [nettype space addrtype space
// connection-address] CRLF
rtc::StringBuilder os;
InitAttrLine(kAttributeRtcp, &os);
os << kSdpDelimiterColon << rtcp_port << " " << kConnectionNettype << " "
<< addr_type << " " << rtcp_ip;
rtcp_line = os.str();
return rtcp_line;
}
// Get candidates according to the mline index from SessionDescriptionInterface.
static void GetCandidatesByMindex(const SessionDescriptionInterface& desci,
int mline_index,
std::vector<Candidate>* candidates) {
if (!candidates) {
return;
}
const IceCandidateCollection* cc = desci.candidates(mline_index);
for (size_t i = 0; i < cc->count(); ++i) {
const IceCandidateInterface* candidate = cc->at(i);
candidates->push_back(candidate->candidate());
}
}
static bool IsValidPort(int port) {
return port >= 0 && port <= 65535;
}
std::string SdpSerialize(const JsepSessionDescription& jdesc) {
const cricket::SessionDescription* desc = jdesc.description();
if (!desc) {
return "";
}
std::string message;
// Session Description.
AddLine(kSessionVersion, &message);
// Session Origin
// RFC 4566
// o=<username> <sess-id> <sess-version> <nettype> <addrtype>
// <unicast-address>
rtc::StringBuilder os;
InitLine(kLineTypeOrigin, kSessionOriginUsername, &os);
const std::string& session_id =
jdesc.session_id().empty() ? kSessionOriginSessionId : jdesc.session_id();
const std::string& session_version = jdesc.session_version().empty()
? kSessionOriginSessionVersion
: jdesc.session_version();
os << " " << session_id << " " << session_version << " "
<< kSessionOriginNettype << " " << kSessionOriginAddrtype << " "
<< kSessionOriginAddress;
AddLine(os.str(), &message);
AddLine(kSessionName, &message);
// Time Description.
AddLine(kTimeDescription, &message);
for (const cricket::SessionDescription::MediaTransportSetting& settings :
desc->MediaTransportSettings()) {
AddMediaTransportLine(settings, &message);
}
// Group
if (desc->HasGroup(cricket::GROUP_TYPE_BUNDLE)) {
std::string group_line = kAttrGroup;
const cricket::ContentGroup* group =
desc->GetGroupByName(cricket::GROUP_TYPE_BUNDLE);
RTC_DCHECK(group != NULL);
for (const std::string& content_name : group->content_names()) {
group_line.append(" ");
group_line.append(content_name);
}
AddLine(group_line, &message);
}
// Mixed one- and two-byte header extension.
if (desc->extmap_allow_mixed()) {
InitAttrLine(kAttributeExtmapAllowMixed, &os);
AddLine(os.str(), &message);
}
// MediaStream semantics
InitAttrLine(kAttributeMsidSemantics, &os);
os << kSdpDelimiterColon << " " << kMediaStreamSemantic;
std::set<std::string> media_stream_ids;
const ContentInfo* audio_content = GetFirstAudioContent(desc);
if (audio_content)
GetMediaStreamIds(audio_content, &media_stream_ids);
const ContentInfo* video_content = GetFirstVideoContent(desc);
if (video_content)
GetMediaStreamIds(video_content, &media_stream_ids);
for (const std::string& id : media_stream_ids) {
os << " " << id;
}
AddLine(os.str(), &message);
// a=ice-lite
//
// TODO(deadbeef): It's weird that we need to iterate TransportInfos for
// this, when it's a session-level attribute. It really should be moved to a
// session-level structure like SessionDescription.
for (const cricket::TransportInfo& transport : desc->transport_infos()) {
if (transport.description.ice_mode == cricket::ICEMODE_LITE) {
InitAttrLine(kAttributeIceLite, &os);
AddLine(os.str(), &message);
break;
}
}
// Preserve the order of the media contents.
int mline_index = -1;
for (const ContentInfo& content : desc->contents()) {
std::vector<Candidate> candidates;
GetCandidatesByMindex(jdesc, ++mline_index, &candidates);
BuildMediaDescription(&content, desc->GetTransportInfoByName(content.name),
content.media_description()->type(), candidates,
desc->msid_signaling(), &message);
}
return message;
}
// Serializes the passed in IceCandidateInterface to a SDP string.
// candidate - The candidate to be serialized.
std::string SdpSerializeCandidate(const IceCandidateInterface& candidate) {
return SdpSerializeCandidate(candidate.candidate());
}
// Serializes a cricket Candidate.
std::string SdpSerializeCandidate(const cricket::Candidate& candidate) {
std::string message;
std::vector<cricket::Candidate> candidates(1, candidate);
BuildCandidate(candidates, true, &message);
// From WebRTC draft section 4.8.1.1 candidate-attribute will be
// just candidate:<candidate> not a=candidate:<blah>CRLF
RTC_DCHECK(message.find("a=") == 0);
message.erase(0, 2);
RTC_DCHECK(message.find(kLineBreak) == message.size() - 2);
message.resize(message.size() - 2);
return message;
}
bool SdpDeserialize(const std::string& message,
JsepSessionDescription* jdesc,
SdpParseError* error) {
std::string session_id;
std::string session_version;
TransportDescription session_td("", "");
RtpHeaderExtensions session_extmaps;
rtc::SocketAddress session_connection_addr;
auto desc = absl::make_unique<cricket::SessionDescription>();
size_t current_pos = 0;
// Session Description
if (!ParseSessionDescription(message, &current_pos, &session_id,
&session_version, &session_td, &session_extmaps,
&session_connection_addr, desc.get(), error)) {
return false;
}
// Media Description
std::vector<std::unique_ptr<JsepIceCandidate>> candidates;
if (!ParseMediaDescription(message, session_td, session_extmaps, &current_pos,
session_connection_addr, desc.get(), &candidates,
error)) {
return false;
}
jdesc->Initialize(std::move(desc), session_id, session_version);
for (const auto& candidate : candidates) {
jdesc->AddCandidate(candidate.get());
}
return true;
}
bool SdpDeserializeCandidate(const std::string& message,
JsepIceCandidate* jcandidate,
SdpParseError* error) {
RTC_DCHECK(jcandidate != NULL);
Candidate candidate;
if (!ParseCandidate(message, &candidate, error, true)) {
return false;
}
jcandidate->SetCandidate(candidate);
return true;
}
bool SdpDeserializeCandidate(const std::string& transport_name,
const std::string& message,
cricket::Candidate* candidate,
SdpParseError* error) {
RTC_DCHECK(candidate != nullptr);
if (!ParseCandidate(message, candidate, error, true)) {
return false;
}
candidate->set_transport_name(transport_name);
return true;
}
bool ParseCandidate(const std::string& message,
Candidate* candidate,
SdpParseError* error,
bool is_raw) {
RTC_DCHECK(candidate != NULL);
// Get the first line from |message|.
std::string first_line = message;
size_t pos = 0;
GetLine(message, &pos, &first_line);
// Makes sure |message| contains only one line.
if (message.size() > first_line.size()) {
std::string left, right;
if (rtc::tokenize_first(message, kNewLineChar, &left, &right) &&
!right.empty()) {
return ParseFailed(message, 0, "Expect one line only", error);
}
}
// From WebRTC draft section 4.8.1.1 candidate-attribute should be
// candidate:<candidate> when trickled, but we still support
// a=candidate:<blah>CRLF for backward compatibility and for parsing a line
// from the SDP.
if (IsLineType(first_line, kLineTypeAttributes)) {
first_line = first_line.substr(kLinePrefixLength);
}
std::string attribute_candidate;
std::string candidate_value;
// |first_line| must be in the form of "candidate:<value>".
if (!rtc::tokenize_first(first_line, kSdpDelimiterColonChar,
&attribute_candidate, &candidate_value) ||
attribute_candidate != kAttributeCandidate) {
if (is_raw) {
rtc::StringBuilder description;
description << "Expect line: " << kAttributeCandidate << ":"
<< "<candidate-str>";
return ParseFailed(first_line, 0, description.str(), error);
} else {
return ParseFailedExpectLine(first_line, 0, kLineTypeAttributes,
kAttributeCandidate, error);
}
}
std::vector<std::string> fields;
rtc::split(candidate_value, kSdpDelimiterSpaceChar, &fields);
// RFC 5245
// a=candidate:<foundation> <component-id> <transport> <priority>
// <connection-address> <port> typ <candidate-types>
// [raddr <connection-address>] [rport <port>]
// *(SP extension-att-name SP extension-att-value)
const size_t expected_min_fields = 8;
if (fields.size() < expected_min_fields ||
(fields[6] != kAttributeCandidateTyp)) {
return ParseFailedExpectMinFieldNum(first_line, expected_min_fields, error);
}
const std::string& foundation = fields[0];
int component_id = 0;
if (!GetValueFromString(first_line, fields[1], &component_id, error)) {
return false;
}
const std::string& transport = fields[2];
uint32_t priority = 0;
if (!GetValueFromString(first_line, fields[3], &priority, error)) {
return false;
}
const std::string& connection_address = fields[4];
int port = 0;
if (!GetValueFromString(first_line, fields[5], &port, error)) {
return false;
}
if (!IsValidPort(port)) {
return ParseFailed(first_line, "Invalid port number.", error);
}
SocketAddress address(connection_address, port);
cricket::ProtocolType protocol;
if (!StringToProto(transport.c_str(), &protocol)) {
return ParseFailed(first_line, "Unsupported transport type.", error);
}
switch (protocol) {
case cricket::PROTO_UDP:
case cricket::PROTO_TCP:
case cricket::PROTO_SSLTCP:
// Supported protocol.
break;
default:
return ParseFailed(first_line, "Unsupported transport type.", error);
}
std::string candidate_type;
const std::string& type = fields[7];
if (type == kCandidateHost) {
candidate_type = cricket::LOCAL_PORT_TYPE;
} else if (type == kCandidateSrflx) {
candidate_type = cricket::STUN_PORT_TYPE;
} else if (type == kCandidateRelay) {
candidate_type = cricket::RELAY_PORT_TYPE;
} else if (type == kCandidatePrflx) {
candidate_type = cricket::PRFLX_PORT_TYPE;
} else {
return ParseFailed(first_line, "Unsupported candidate type.", error);
}
size_t current_position = expected_min_fields;
SocketAddress related_address;
// The 2 optional fields for related address
// [raddr <connection-address>] [rport <port>]
if (fields.size() >= (current_position + 2) &&
fields[current_position] == kAttributeCandidateRaddr) {
related_address.SetIP(fields[++current_position]);
++current_position;
}
if (fields.size() >= (current_position + 2) &&
fields[current_position] == kAttributeCandidateRport) {
int port = 0;
if (!GetValueFromString(first_line, fields[++current_position], &port,
error)) {
return false;
}
if (!IsValidPort(port)) {
return ParseFailed(first_line, "Invalid port number.", error);
}
related_address.SetPort(port);
++current_position;
}
// If this is a TCP candidate, it has additional extension as defined in
// RFC 6544.
std::string tcptype;
if (fields.size() >= (current_position + 2) &&
fields[current_position] == kTcpCandidateType) {
tcptype = fields[++current_position];
++current_position;
if (tcptype != cricket::TCPTYPE_ACTIVE_STR &&
tcptype != cricket::TCPTYPE_PASSIVE_STR &&
tcptype != cricket::TCPTYPE_SIMOPEN_STR) {
return ParseFailed(first_line, "Invalid TCP candidate type.", error);
}
if (protocol != cricket::PROTO_TCP) {
return ParseFailed(first_line, "Invalid non-TCP candidate", error);
}
}
// Extension
// Though non-standard, we support the ICE ufrag and pwd being signaled on
// the candidate to avoid issues with confusing which generation a candidate
// belongs to when trickling multiple generations at the same time.
std::string username;
std::string password;
uint32_t generation = 0;
uint16_t network_id = 0;
uint16_t network_cost = 0;
for (size_t i = current_position; i + 1 < fields.size(); ++i) {
// RFC 5245
// *(SP extension-att-name SP extension-att-value)
if (fields[i] == kAttributeCandidateGeneration) {
if (!GetValueFromString(first_line, fields[++i], &generation, error)) {
return false;
}
} else if (fields[i] == kAttributeCandidateUfrag) {
username = fields[++i];
} else if (fields[i] == kAttributeCandidatePwd) {
password = fields[++i];
} else if (fields[i] == kAttributeCandidateNetworkId) {
if (!GetValueFromString(first_line, fields[++i], &network_id, error)) {
return false;
}
} else if (fields[i] == kAttributeCandidateNetworkCost) {
if (!GetValueFromString(first_line, fields[++i], &network_cost, error)) {
return false;
}
network_cost = std::min(network_cost, rtc::kNetworkCostMax);
} else {
// Skip the unknown extension.
++i;
}
}
*candidate = Candidate(component_id, cricket::ProtoToString(protocol),
address, priority, username, password, candidate_type,
generation, foundation, network_id, network_cost);
candidate->set_related_address(related_address);
candidate->set_tcptype(tcptype);
return true;
}
bool ParseIceOptions(const std::string& line,
std::vector<std::string>* transport_options,
SdpParseError* error) {
std::string ice_options;
if (!GetValue(line, kAttributeIceOption, &ice_options, error)) {
return false;
}
std::vector<std::string> fields;
rtc::split(ice_options, kSdpDelimiterSpaceChar, &fields);
for (size_t i = 0; i < fields.size(); ++i) {
transport_options->push_back(fields[i]);
}
return true;
}
bool ParseSctpPort(const std::string& line,
int* sctp_port,
SdpParseError* error) {
// draft-ietf-mmusic-sctp-sdp-26
// a=sctp-port
std::vector<std::string> fields;
const size_t expected_min_fields = 2;
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterColonChar, &fields);
if (fields.size() < expected_min_fields) {
fields.resize(0);
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar, &fields);
}
if (fields.size() < expected_min_fields) {
return ParseFailedExpectMinFieldNum(line, expected_min_fields, error);
}
if (!rtc::FromString(fields[1], sctp_port)) {
return ParseFailed(line, "Invalid sctp port value.", error);
}
return true;
}
bool ParseSctpMaxMessageSize(const std::string& line,
int* max_message_size,
SdpParseError* error) {
// draft-ietf-mmusic-sctp-sdp-26
// a=max-message-size:199999
std::vector<std::string> fields;
const size_t expected_min_fields = 2;
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterColonChar, &fields);
if (fields.size() < expected_min_fields) {
return ParseFailedExpectMinFieldNum(line, expected_min_fields, error);
}
if (!rtc::FromString(fields[1], max_message_size)) {
return ParseFailed(line, "Invalid SCTP max message size.", error);
}
return true;
}
bool ParseExtmap(const std::string& line,
RtpExtension* extmap,
SdpParseError* error) {
// RFC 5285
// a=extmap:<value>["/"<direction>] <URI> <extensionattributes>
std::vector<std::string> fields;
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar, &fields);
const size_t expected_min_fields = 2;
if (fields.size() < expected_min_fields) {
return ParseFailedExpectMinFieldNum(line, expected_min_fields, error);
}
std::string uri = fields[1];
std::string value_direction;
if (!GetValue(fields[0], kAttributeExtmap, &value_direction, error)) {
return false;
}
std::vector<std::string> sub_fields;
rtc::split(value_direction, kSdpDelimiterSlashChar, &sub_fields);
int value = 0;
if (!GetValueFromString(line, sub_fields[0], &value, error)) {
return false;
}
bool encrypted = false;
if (uri == RtpExtension::kEncryptHeaderExtensionsUri) {
// RFC 6904
// a=extmap:<value["/"<direction>] urn:ietf:params:rtp-hdrext:encrypt <URI>
// <extensionattributes>
const size_t expected_min_fields_encrypted = expected_min_fields + 1;
if (fields.size() < expected_min_fields_encrypted) {
return ParseFailedExpectMinFieldNum(line, expected_min_fields_encrypted,
error);
}
encrypted = true;
uri = fields[2];
if (uri == RtpExtension::kEncryptHeaderExtensionsUri) {
return ParseFailed(line, "Recursive encrypted header.", error);
}
}
*extmap = RtpExtension(uri, value, encrypted);
return true;
}
static void BuildSctpContentAttributes(
std::string* message,
const cricket::SctpDataContentDescription* data_desc) {
rtc::StringBuilder os;
if (data_desc->use_sctpmap()) {
// draft-ietf-mmusic-sctp-sdp-04
// a=sctpmap:sctpmap-number protocol [streams]
rtc::StringBuilder os;
InitAttrLine(kAttributeSctpmap, &os);
os << kSdpDelimiterColon << data_desc->port() << kSdpDelimiterSpace
<< kDefaultSctpmapProtocol << kSdpDelimiterSpace
<< cricket::kMaxSctpStreams;
AddLine(os.str(), message);
} else {
// draft-ietf-mmusic-sctp-sdp-23
// a=sctp-port:<port>
InitAttrLine(kAttributeSctpPort, &os);
os << kSdpDelimiterColon << data_desc->port();
AddLine(os.str(), message);
if (data_desc->max_message_size() != kDefaultSctpMaxMessageSize) {
InitAttrLine(kAttributeMaxMessageSize, &os);
os << kSdpDelimiterColon << data_desc->max_message_size();
AddLine(os.str(), message);
}
}
}
void BuildMediaDescription(const ContentInfo* content_info,
const TransportInfo* transport_info,
const cricket::MediaType media_type,
const std::vector<Candidate>& candidates,
int msid_signaling,
std::string* message) {
RTC_DCHECK(message != NULL);
if (content_info == NULL || message == NULL) {
return;
}
rtc::StringBuilder os;
const MediaContentDescription* media_desc = content_info->media_description();
RTC_DCHECK(media_desc);
// RFC 4566
// m=<media> <port> <proto> <fmt>
// fmt is a list of payload type numbers that MAY be used in the session.
const char* type = NULL;
if (media_type == cricket::MEDIA_TYPE_AUDIO)
type = kMediaTypeAudio;
else if (media_type == cricket::MEDIA_TYPE_VIDEO)
type = kMediaTypeVideo;
else if (media_type == cricket::MEDIA_TYPE_DATA)
type = kMediaTypeData;
else
RTC_NOTREACHED();
std::string fmt;
if (media_type == cricket::MEDIA_TYPE_VIDEO) {
const VideoContentDescription* video_desc = media_desc->as_video();
for (const cricket::VideoCodec& codec : video_desc->codecs()) {
fmt.append(" ");
fmt.append(rtc::ToString(codec.id));
}
} else if (media_type == cricket::MEDIA_TYPE_AUDIO) {
const AudioContentDescription* audio_desc = media_desc->as_audio();
for (const cricket::AudioCodec& codec : audio_desc->codecs()) {
fmt.append(" ");
fmt.append(rtc::ToString(codec.id));
}
} else if (media_type == cricket::MEDIA_TYPE_DATA) {
const cricket::SctpDataContentDescription* sctp_data_desc =
media_desc->as_sctp();
if (sctp_data_desc) {
fmt.append(" ");
if (sctp_data_desc->use_sctpmap()) {
fmt.append(rtc::ToString(sctp_data_desc->port()));
} else {
fmt.append(kDefaultSctpmapProtocol);
}
} else {
const RtpDataContentDescription* rtp_data_desc =
media_desc->as_rtp_data();
for (const cricket::RtpDataCodec& codec : rtp_data_desc->codecs()) {
fmt.append(" ");
fmt.append(rtc::ToString(codec.id));
}
}
}
// The fmt must never be empty. If no codecs are found, set the fmt attribute
// to 0.
if (fmt.empty()) {
fmt = " 0";
}
// The port number in the m line will be updated later when associated with
// the candidates.
//
// A port value of 0 indicates that the m= section is rejected.
// RFC 3264
// To reject an offered stream, the port number in the corresponding stream in
// the answer MUST be set to zero.
//
// However, the BUNDLE draft adds a new meaning to port zero, when used along
// with a=bundle-only.
std::string port = kDummyPort;
if (content_info->rejected || content_info->bundle_only) {
port = kMediaPortRejected;
} else if (!media_desc->connection_address().IsNil()) {
port = rtc::ToString(media_desc->connection_address().port());
}
rtc::SSLFingerprint* fp =
(transport_info) ? transport_info->description.identity_fingerprint.get()
: NULL;
// Add the m and c lines.
InitLine(kLineTypeMedia, type, &os);
os << " " << port << " " << media_desc->protocol() << fmt;
AddLine(os.str(), message);
InitLine(kLineTypeConnection, kConnectionNettype, &os);
if (media_desc->connection_address().IsNil()) {
os << " " << kConnectionIpv4Addrtype << " " << kDummyAddress;
} else if (media_desc->connection_address().family() == AF_INET) {
os << " " << kConnectionIpv4Addrtype << " "
<< media_desc->connection_address().ipaddr().ToString();
} else if (media_desc->connection_address().family() == AF_INET6) {
os << " " << kConnectionIpv6Addrtype << " "
<< media_desc->connection_address().ipaddr().ToString();
} else if (!media_desc->connection_address().hostname().empty()) {
// For hostname candidates, we use c=IN IP4 <hostname>.
os << " " << kConnectionIpv4Addrtype << " "
<< media_desc->connection_address().hostname();
} else {
os << " " << kConnectionIpv4Addrtype << " " << kDummyAddress;
}
AddLine(os.str(), message);
// RFC 4566
// b=AS:<bandwidth>
if (media_desc->bandwidth() >= 1000) {
InitLine(kLineTypeSessionBandwidth, kApplicationSpecificMaximum, &os);
os << kSdpDelimiterColon << (media_desc->bandwidth() / 1000);
AddLine(os.str(), message);
}
// Add the a=bundle-only line.
if (content_info->bundle_only) {
InitAttrLine(kAttributeBundleOnly, &os);
AddLine(os.str(), message);
}
// Add the a=rtcp line.
if (cricket::IsRtpProtocol(media_desc->protocol())) {
std::string rtcp_line = GetRtcpLine(candidates);
if (!rtcp_line.empty()) {
AddLine(rtcp_line, message);
}
}
// Build the a=candidate lines. We don't include ufrag and pwd in the
// candidates in the SDP to avoid redundancy.
BuildCandidate(candidates, false, message);
// Use the transport_info to build the media level ice-ufrag and ice-pwd.
if (transport_info) {
// RFC 5245
// ice-pwd-att = "ice-pwd" ":" password
// ice-ufrag-att = "ice-ufrag" ":" ufrag
// ice-ufrag
if (!transport_info->description.ice_ufrag.empty()) {
InitAttrLine(kAttributeIceUfrag, &os);
os << kSdpDelimiterColon << transport_info->description.ice_ufrag;
AddLine(os.str(), message);
}
// ice-pwd
if (!transport_info->description.ice_pwd.empty()) {
InitAttrLine(kAttributeIcePwd, &os);
os << kSdpDelimiterColon << transport_info->description.ice_pwd;
AddLine(os.str(), message);
}
// draft-petithuguenin-mmusic-ice-attributes-level-03
BuildIceOptions(transport_info->description.transport_options, message);
// RFC 4572
// fingerprint-attribute =
// "fingerprint" ":" hash-func SP fingerprint
if (fp) {
// Insert the fingerprint attribute.
InitAttrLine(kAttributeFingerprint, &os);
os << kSdpDelimiterColon << fp->algorithm << kSdpDelimiterSpace
<< fp->GetRfc4572Fingerprint();
AddLine(os.str(), message);
// Inserting setup attribute.
if (transport_info->description.connection_role !=
cricket::CONNECTIONROLE_NONE) {
// Making sure we are not using "passive" mode.
cricket::ConnectionRole role =
transport_info->description.connection_role;
std::string dtls_role_str;
const bool success =
cricket::ConnectionRoleToString(role, &dtls_role_str);
RTC_DCHECK(success);
InitAttrLine(kAttributeSetup, &os);
os << kSdpDelimiterColon << dtls_role_str;
AddLine(os.str(), message);
}
}
}
// RFC 3388
// mid-attribute = "a=mid:" identification-tag
// identification-tag = token
// Use the content name as the mid identification-tag.
InitAttrLine(kAttributeMid, &os);
os << kSdpDelimiterColon << content_info->name;
AddLine(os.str(), message);
if (cricket::IsDtlsSctp(media_desc->protocol())) {
const cricket::SctpDataContentDescription* data_desc =
media_desc->as_sctp();
BuildSctpContentAttributes(message, data_desc);
} else if (cricket::IsRtpProtocol(media_desc->protocol())) {
BuildRtpContentAttributes(media_desc, media_type, msid_signaling, message);
}
}
void BuildRtpContentAttributes(const MediaContentDescription* media_desc,
const cricket::MediaType media_type,
int msid_signaling,
std::string* message) {
SdpSerializer serializer;
rtc::StringBuilder os;
// RFC 8285
// a=extmap-allow-mixed
// The attribute MUST be either on session level or media level. We support
// responding on both levels, however, we don't respond on media level if it's
// set on session level.
if (media_desc->extmap_allow_mixed_enum() ==
MediaContentDescription::kMedia) {
InitAttrLine(kAttributeExtmapAllowMixed, &os);
AddLine(os.str(), message);
}
// RFC 8285
// a=extmap:<value>["/"<direction>] <URI> <extensionattributes>
// The definitions MUST be either all session level or all media level. This
// implementation uses all media level.
for (size_t i = 0; i < media_desc->rtp_header_extensions().size(); ++i) {
const RtpExtension& extension = media_desc->rtp_header_extensions()[i];
InitAttrLine(kAttributeExtmap, &os);
os << kSdpDelimiterColon << extension.id;
if (extension.encrypt) {
os << kSdpDelimiterSpace << RtpExtension::kEncryptHeaderExtensionsUri;
}
os << kSdpDelimiterSpace << extension.uri;
AddLine(os.str(), message);
}
// RFC 3264
// a=sendrecv || a=sendonly || a=sendrecv || a=inactive
switch (media_desc->direction()) {
case RtpTransceiverDirection::kInactive:
InitAttrLine(kAttributeInactive, &os);
break;
case RtpTransceiverDirection::kSendOnly:
InitAttrLine(kAttributeSendOnly, &os);
break;
case RtpTransceiverDirection::kRecvOnly:
InitAttrLine(kAttributeRecvOnly, &os);
break;
case RtpTransceiverDirection::kSendRecv:
default:
InitAttrLine(kAttributeSendRecv, &os);
break;
}
AddLine(os.str(), message);
// Specified in https://datatracker.ietf.org/doc/draft-ietf-mmusic-msid/16/
// a=msid:<msid-id> <msid-appdata>
// The msid-id is a 1*64 token char representing the media stream id, and the
// msid-appdata is a 1*64 token char representing the track id. There is a
// line for every media stream, with a special msid-id value of "-"
// representing no streams. The value of "msid-appdata" MUST be identical for
// all lines.
if (msid_signaling & cricket::kMsidSignalingMediaSection) {
const StreamParamsVec& streams = media_desc->streams();
if (streams.size() == 1u) {
const StreamParams& track = streams[0];
std::vector<std::string> stream_ids = track.stream_ids();
if (stream_ids.empty()) {
stream_ids.push_back(kNoStreamMsid);
}
for (const std::string& stream_id : stream_ids) {
InitAttrLine(kAttributeMsid, &os);
os << kSdpDelimiterColon << stream_id << kSdpDelimiterSpace << track.id;
AddLine(os.str(), message);
}
} else if (streams.size() > 1u) {
RTC_LOG(LS_WARNING)
<< "Trying to serialize Unified Plan SDP with more than "
"one track in a media section. Omitting 'a=msid'.";
}
}
// RFC 5761
// a=rtcp-mux
if (media_desc->rtcp_mux()) {
InitAttrLine(kAttributeRtcpMux, &os);
AddLine(os.str(), message);
}
// RFC 5506
// a=rtcp-rsize
if (media_desc->rtcp_reduced_size()) {
InitAttrLine(kAttributeRtcpReducedSize, &os);
AddLine(os.str(), message);
}
if (media_desc->conference_mode()) {
InitAttrLine(kAttributeXGoogleFlag, &os);
os << kSdpDelimiterColon << kValueConference;
AddLine(os.str(), message);
}
// RFC 4568
// a=crypto:<tag> <crypto-suite> <key-params> [<session-params>]
for (const CryptoParams& crypto_params : media_desc->cryptos()) {
InitAttrLine(kAttributeCrypto, &os);
os << kSdpDelimiterColon << crypto_params.tag << " "
<< crypto_params.cipher_suite << " " << crypto_params.key_params;
if (!crypto_params.session_params.empty()) {
os << " " << crypto_params.session_params;
}
AddLine(os.str(), message);
}
// RFC 4566
// a=rtpmap:<payload type> <encoding name>/<clock rate>
// [/<encodingparameters>]
BuildRtpMap(media_desc, media_type, message);
for (const StreamParams& track : media_desc->streams()) {
// Build the ssrc-group lines.
for (const SsrcGroup& ssrc_group : track.ssrc_groups) {
// RFC 5576
// a=ssrc-group:<semantics> <ssrc-id> ...
if (ssrc_group.ssrcs.empty()) {
continue;
}
InitAttrLine(kAttributeSsrcGroup, &os);
os << kSdpDelimiterColon << ssrc_group.semantics;
for (uint32_t ssrc : ssrc_group.ssrcs) {
os << kSdpDelimiterSpace << rtc::ToString(ssrc);
}
AddLine(os.str(), message);
}
// Build the ssrc lines for each ssrc.
for (uint32_t ssrc : track.ssrcs) {
// RFC 5576
// a=ssrc:<ssrc-id> cname:<value>
AddSsrcLine(ssrc, kSsrcAttributeCname, track.cname, message);
if (msid_signaling & cricket::kMsidSignalingSsrcAttribute) {
// draft-alvestrand-mmusic-msid-00
// a=ssrc:<ssrc-id> msid:identifier [appdata]
// The appdata consists of the "id" attribute of a MediaStreamTrack,
// which corresponds to the "id" attribute of StreamParams.
// Since a=ssrc msid signaling is used in Plan B SDP semantics, and
// multiple stream ids are not supported for Plan B, we are only adding
// a line for the first media stream id here.
const std::string& track_stream_id = track.first_stream_id();
// We use a special msid-id value of "-" to represent no streams,
// for Unified Plan compatibility. Plan B will always have a
// track_stream_id.
const std::string& stream_id =
track_stream_id.empty() ? kNoStreamMsid : track_stream_id;
InitAttrLine(kAttributeSsrc, &os);
os << kSdpDelimiterColon << ssrc << kSdpDelimiterSpace
<< kSsrcAttributeMsid << kSdpDelimiterColon << stream_id
<< kSdpDelimiterSpace << track.id;
AddLine(os.str(), message);
// TODO(ronghuawu): Remove below code which is for backward
// compatibility.
// draft-alvestrand-rtcweb-mid-01
// a=ssrc:<ssrc-id> mslabel:<value>
// The label isn't yet defined.
// a=ssrc:<ssrc-id> label:<value>
AddSsrcLine(ssrc, kSsrcAttributeMslabel, stream_id, message);
AddSsrcLine(ssrc, kSSrcAttributeLabel, track.id, message);
}
}
// Build the rid lines for each layer of the track
for (const RidDescription& rid_description : track.rids()) {
InitAttrLine(kAttributeRid, &os);
os << kSdpDelimiterColon
<< serializer.SerializeRidDescription(rid_description);
AddLine(os.str(), message);
}
}
// Simulcast (a=simulcast)
// https://tools.ietf.org/html/draft-ietf-mmusic-sdp-simulcast-13#section-5.1
if (media_desc->HasSimulcast()) {
const auto& simulcast = media_desc->simulcast_description();
InitAttrLine(kAttributeSimulcast, &os);
os << kSdpDelimiterColon
<< serializer.SerializeSimulcastDescription(simulcast);
AddLine(os.str(), message);
}
}
void WriteFmtpHeader(int payload_type, rtc::StringBuilder* os) {
// fmtp header: a=fmtp:|payload_type| <parameters>
// Add a=fmtp
InitAttrLine(kAttributeFmtp, os);
// Add :|payload_type|
*os << kSdpDelimiterColon << payload_type;
}
void WriteRtcpFbHeader(int payload_type, rtc::StringBuilder* os) {
// rtcp-fb header: a=rtcp-fb:|payload_type|
// <parameters>/<ccm <ccm_parameters>>
// Add a=rtcp-fb
InitAttrLine(kAttributeRtcpFb, os);
// Add :
*os << kSdpDelimiterColon;
if (payload_type == kWildcardPayloadType) {
*os << "*";
} else {
*os << payload_type;
}
}
void WriteFmtpParameter(const std::string& parameter_name,
const std::string& parameter_value,
rtc::StringBuilder* os) {
// fmtp parameters: |parameter_name|=|parameter_value|
*os << parameter_name << kSdpDelimiterEqual << parameter_value;
}
void WriteFmtpParameters(const cricket::CodecParameterMap& parameters,
rtc::StringBuilder* os) {
bool first = true;
for (const auto& entry : parameters) {
const std::string& key = entry.first;
const std::string& value = entry.second;
// Parameters are a semicolon-separated list, no spaces.
// The list is separated from the header by a space.
if (first) {
*os << kSdpDelimiterSpace;
first = false;
} else {
*os << kSdpDelimiterSemicolon;
}
WriteFmtpParameter(key, value, os);
}
}
bool IsFmtpParam(const std::string& name) {
// RFC 4855, section 3 specifies the mapping of media format parameters to SDP
// parameters. Only ptime, maxptime, channels and rate are placed outside of
// the fmtp line. In WebRTC, channels and rate are already handled separately
// and thus not included in the CodecParameterMap.
return name != kCodecParamPTime && name != kCodecParamMaxPTime;
}
// Retreives fmtp parameters from |params|, which may contain other parameters
// as well, and puts them in |fmtp_parameters|.
void GetFmtpParams(const cricket::CodecParameterMap& params,
cricket::CodecParameterMap* fmtp_parameters) {
for (const auto& entry : params) {
const std::string& key = entry.first;
const std::string& value = entry.second;
if (IsFmtpParam(key)) {
(*fmtp_parameters)[key] = value;
}
}
}
template <class T>
void AddFmtpLine(const T& codec, std::string* message) {
cricket::CodecParameterMap fmtp_parameters;
GetFmtpParams(codec.params, &fmtp_parameters);
if (fmtp_parameters.empty()) {
// No need to add an fmtp if it will have no (optional) parameters.
return;
}
rtc::StringBuilder os;
WriteFmtpHeader(codec.id, &os);
WriteFmtpParameters(fmtp_parameters, &os);
AddLine(os.str(), message);
return;
}
template <class T>
void AddRtcpFbLines(const T& codec, std::string* message) {
for (const cricket::FeedbackParam& param : codec.feedback_params.params()) {
rtc::StringBuilder os;
WriteRtcpFbHeader(codec.id, &os);
os << " " << param.id();
if (!param.param().empty()) {
os << " " << param.param();
}
AddLine(os.str(), message);
}
}
bool GetMinValue(const std::vector<int>& values, int* value) {
if (values.empty()) {
return false;
}
auto it = absl::c_min_element(values);
*value = *it;
return true;
}
bool GetParameter(const std::string& name,
const cricket::CodecParameterMap& params,
int* value) {
std::map<std::string, std::string>::const_iterator found = params.find(name);
if (found == params.end()) {
return false;
}
if (!rtc::FromString(found->second, value)) {
return false;
}
return true;
}
void BuildRtpMap(const MediaContentDescription* media_desc,
const cricket::MediaType media_type,
std::string* message) {
RTC_DCHECK(message != NULL);
RTC_DCHECK(media_desc != NULL);
rtc::StringBuilder os;
if (media_type == cricket::MEDIA_TYPE_VIDEO) {
for (const cricket::VideoCodec& codec : media_desc->as_video()->codecs()) {
// RFC 4566
// a=rtpmap:<payload type> <encoding name>/<clock rate>
// [/<encodingparameters>]
if (codec.id != kWildcardPayloadType) {
InitAttrLine(kAttributeRtpmap, &os);
os << kSdpDelimiterColon << codec.id << " " << codec.name << "/"
<< cricket::kVideoCodecClockrate;
AddLine(os.str(), message);
}
AddRtcpFbLines(codec, message);
AddFmtpLine(codec, message);
}
} else if (media_type == cricket::MEDIA_TYPE_AUDIO) {
std::vector<int> ptimes;
std::vector<int> maxptimes;
int max_minptime = 0;
for (const cricket::AudioCodec& codec : media_desc->as_audio()->codecs()) {
RTC_DCHECK(!codec.name.empty());
// RFC 4566
// a=rtpmap:<payload type> <encoding name>/<clock rate>
// [/<encodingparameters>]
InitAttrLine(kAttributeRtpmap, &os);
os << kSdpDelimiterColon << codec.id << " ";
os << codec.name << "/" << codec.clockrate;
if (codec.channels != 1) {
os << "/" << codec.channels;
}
AddLine(os.str(), message);
AddRtcpFbLines(codec, message);
AddFmtpLine(codec, message);
int minptime = 0;
if (GetParameter(kCodecParamMinPTime, codec.params, &minptime)) {
max_minptime = std::max(minptime, max_minptime);
}
int ptime;
if (GetParameter(kCodecParamPTime, codec.params, &ptime)) {
ptimes.push_back(ptime);
}
int maxptime;
if (GetParameter(kCodecParamMaxPTime, codec.params, &maxptime)) {
maxptimes.push_back(maxptime);
}
}
// Populate the maxptime attribute with the smallest maxptime of all codecs
// under the same m-line.
int min_maxptime = INT_MAX;
if (GetMinValue(maxptimes, &min_maxptime)) {
AddAttributeLine(kCodecParamMaxPTime, min_maxptime, message);
}
RTC_DCHECK(min_maxptime > max_minptime);
// Populate the ptime attribute with the smallest ptime or the largest
// minptime, whichever is the largest, for all codecs under the same m-line.
int ptime = INT_MAX;
if (GetMinValue(ptimes, &ptime)) {
ptime = std::min(ptime, min_maxptime);
ptime = std::max(ptime, max_minptime);
AddAttributeLine(kCodecParamPTime, ptime, message);
}
} else if (media_type == cricket::MEDIA_TYPE_DATA) {
if (media_desc->as_rtp_data()) {
for (const cricket::RtpDataCodec& codec :
media_desc->as_rtp_data()->codecs()) {
// RFC 4566
// a=rtpmap:<payload type> <encoding name>/<clock rate>
// [/<encodingparameters>]
InitAttrLine(kAttributeRtpmap, &os);
os << kSdpDelimiterColon << codec.id << " " << codec.name << "/"
<< codec.clockrate;
AddLine(os.str(), message);
}
}
}
}
void BuildCandidate(const std::vector<Candidate>& candidates,
bool include_ufrag,
std::string* message) {
rtc::StringBuilder os;
for (const Candidate& candidate : candidates) {
// RFC 5245
// a=candidate:<foundation> <component-id> <transport> <priority>
// <connection-address> <port> typ <candidate-types>
// [raddr <connection-address>] [rport <port>]
// *(SP extension-att-name SP extension-att-value)
std::string type;
// Map the cricket candidate type to "host" / "srflx" / "prflx" / "relay"
if (candidate.type() == cricket::LOCAL_PORT_TYPE) {
type = kCandidateHost;
} else if (candidate.type() == cricket::STUN_PORT_TYPE) {
type = kCandidateSrflx;
} else if (candidate.type() == cricket::RELAY_PORT_TYPE) {
type = kCandidateRelay;
} else if (candidate.type() == cricket::PRFLX_PORT_TYPE) {
type = kCandidatePrflx;
// Peer reflexive candidate may be signaled for being removed.
} else {
RTC_NOTREACHED();
// Never write out candidates if we don't know the type.
continue;
}
InitAttrLine(kAttributeCandidate, &os);
os << kSdpDelimiterColon << candidate.foundation() << " "
<< candidate.component() << " " << candidate.protocol() << " "
<< candidate.priority() << " "
<< (candidate.address().ipaddr().IsNil()
? candidate.address().hostname()
: candidate.address().ipaddr().ToString())
<< " " << candidate.address().PortAsString() << " "
<< kAttributeCandidateTyp << " " << type << " ";
// Related address
if (!candidate.related_address().IsNil()) {
os << kAttributeCandidateRaddr << " "
<< candidate.related_address().ipaddr().ToString() << " "
<< kAttributeCandidateRport << " "
<< candidate.related_address().PortAsString() << " ";
}
if (candidate.protocol() == cricket::TCP_PROTOCOL_NAME) {
os << kTcpCandidateType << " " << candidate.tcptype() << " ";
}
// Extensions
os << kAttributeCandidateGeneration << " " << candidate.generation();
if (include_ufrag && !candidate.username().empty()) {
os << " " << kAttributeCandidateUfrag << " " << candidate.username();
}
if (candidate.network_id() > 0) {
os << " " << kAttributeCandidateNetworkId << " "
<< candidate.network_id();
}
if (candidate.network_cost() > 0) {
os << " " << kAttributeCandidateNetworkCost << " "
<< candidate.network_cost();
}
AddLine(os.str(), message);
}
}
void BuildIceOptions(const std::vector<std::string>& transport_options,
std::string* message) {
if (!transport_options.empty()) {
rtc::StringBuilder os;
InitAttrLine(kAttributeIceOption, &os);
os << kSdpDelimiterColon << transport_options[0];
for (size_t i = 1; i < transport_options.size(); ++i) {
os << kSdpDelimiterSpace << transport_options[i];
}
AddLine(os.str(), message);
}
}
bool ParseConnectionData(const std::string& line,
rtc::SocketAddress* addr,
SdpParseError* error) {
// Parse the line from left to right.
std::string token;
std::string rightpart;
// RFC 4566
// c=<nettype> <addrtype> <connection-address>
// Skip the "c="
if (!rtc::tokenize_first(line, kSdpDelimiterEqualChar, &token, &rightpart)) {
return ParseFailed(line, "Failed to parse the network type.", error);
}
// Extract and verify the <nettype>
if (!rtc::tokenize_first(rightpart, kSdpDelimiterSpaceChar, &token,
&rightpart) ||
token != kConnectionNettype) {
return ParseFailed(line,
"Failed to parse the connection data. The network type "
"is not currently supported.",
error);
}
// Extract the "<addrtype>" and "<connection-address>".
if (!rtc::tokenize_first(rightpart, kSdpDelimiterSpaceChar, &token,
&rightpart)) {
return ParseFailed(line, "Failed to parse the address type.", error);
}
// The rightpart part should be the IP address without the slash which is used
// for multicast.
if (rightpart.find('/') != std::string::npos) {
return ParseFailed(line,
"Failed to parse the connection data. Multicast is not "
"currently supported.",
error);
}
addr->SetIP(rightpart);
// Verify that the addrtype matches the type of the parsed address.
if ((addr->family() == AF_INET && token != "IP4") ||
(addr->family() == AF_INET6 && token != "IP6")) {
addr->Clear();
return ParseFailed(
line,
"Failed to parse the connection data. The address type is mismatching.",
error);
}
return true;
}
bool ParseMediaTransportLine(const std::string& line,
std::string* transport_name,
std::string* transport_setting,
SdpParseError* error) {
std::string value;
if (!GetValue(line, kMediaTransportSettingLine, &value, error)) {
return false;
}
std::string media_transport_settings_base64;
if (!rtc::tokenize_first(value, kSdpDelimiterColonChar, transport_name,
&media_transport_settings_base64)) {
return ParseFailedGetValue(line, kMediaTransportSettingLine, error);
}
if (!rtc::Base64::Decode(media_transport_settings_base64,
rtc::Base64::DO_STRICT, transport_setting,
nullptr)) {
return ParseFailedGetValue(line, kMediaTransportSettingLine, error);
}
return true;
}
bool ParseSessionDescription(const std::string& message,
size_t* pos,
std::string* session_id,
std::string* session_version,
TransportDescription* session_td,
RtpHeaderExtensions* session_extmaps,
rtc::SocketAddress* connection_addr,
cricket::SessionDescription* desc,
SdpParseError* error) {
std::string line;
desc->set_msid_supported(false);
desc->set_extmap_allow_mixed(false);
// RFC 4566
// v= (protocol version)
if (!GetLineWithType(message, pos, &line, kLineTypeVersion)) {
return ParseFailedExpectLine(message, *pos, kLineTypeVersion, std::string(),
error);
}
// RFC 4566
// o=<username> <sess-id> <sess-version> <nettype> <addrtype>
// <unicast-address>
if (!GetLineWithType(message, pos, &line, kLineTypeOrigin)) {
return ParseFailedExpectLine(message, *pos, kLineTypeOrigin, std::string(),
error);
}
std::vector<std::string> fields;
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar, &fields);
const size_t expected_fields = 6;
if (fields.size() != expected_fields) {
return ParseFailedExpectFieldNum(line, expected_fields, error);
}
*session_id = fields[1];
*session_version = fields[2];
// RFC 4566
// s= (session name)
if (!GetLineWithType(message, pos, &line, kLineTypeSessionName)) {
return ParseFailedExpectLine(message, *pos, kLineTypeSessionName,
std::string(), error);
}
// absl::optional lines
// Those are the optional lines, so shouldn't return false if not present.
// RFC 4566
// i=* (session information)
GetLineWithType(message, pos, &line, kLineTypeSessionInfo);
// RFC 4566
// u=* (URI of description)
GetLineWithType(message, pos, &line, kLineTypeSessionUri);
// RFC 4566
// e=* (email address)
GetLineWithType(message, pos, &line, kLineTypeSessionEmail);
// RFC 4566
// p=* (phone number)
GetLineWithType(message, pos, &line, kLineTypeSessionPhone);
// RFC 4566
// c=* (connection information -- not required if included in
// all media)
if (GetLineWithType(message, pos, &line, kLineTypeConnection)) {
if (!ParseConnectionData(line, connection_addr, error)) {
return false;
}
}
// RFC 4566
// b=* (zero or more bandwidth information lines)
while (GetLineWithType(message, pos, &line, kLineTypeSessionBandwidth)) {
// By pass zero or more b lines.
}
// RFC 4566
// One or more time descriptions ("t=" and "r=" lines; see below)
// t= (time the session is active)
// r=* (zero or more repeat times)
// Ensure there's at least one time description
if (!GetLineWithType(message, pos, &line, kLineTypeTiming)) {
return ParseFailedExpectLine(message, *pos, kLineTypeTiming, std::string(),
error);
}
while (GetLineWithType(message, pos, &line, kLineTypeRepeatTimes)) {
// By pass zero or more r lines.
}
// Go through the rest of the time descriptions
while (GetLineWithType(message, pos, &line, kLineTypeTiming)) {
while (GetLineWithType(message, pos, &line, kLineTypeRepeatTimes)) {
// By pass zero or more r lines.
}
}
// RFC 4566
// z=* (time zone adjustments)
GetLineWithType(message, pos, &line, kLineTypeTimeZone);
// RFC 4566
// k=* (encryption key)
GetLineWithType(message, pos, &line, kLineTypeEncryptionKey);
// RFC 4566
// a=* (zero or more session attribute lines)
while (GetLineWithType(message, pos, &line, kLineTypeAttributes)) {
if (HasAttribute(line, kAttributeGroup)) {
if (!ParseGroupAttribute(line, desc, error)) {
return false;
}
} else if (HasAttribute(line, kAttributeIceUfrag)) {
if (!GetValue(line, kAttributeIceUfrag, &(session_td->ice_ufrag),
error)) {
return false;
}
} else if (HasAttribute(line, kAttributeIcePwd)) {
if (!GetValue(line, kAttributeIcePwd, &(session_td->ice_pwd), error)) {
return false;
}
} else if (HasAttribute(line, kAttributeIceLite)) {
session_td->ice_mode = cricket::ICEMODE_LITE;
} else if (HasAttribute(line, kAttributeIceOption)) {
if (!ParseIceOptions(line, &(session_td->transport_options), error)) {
return false;
}
} else if (HasAttribute(line, kAttributeFingerprint)) {
if (session_td->identity_fingerprint.get()) {
return ParseFailed(
line,
"Can't have multiple fingerprint attributes at the same level.",
error);
}
std::unique_ptr<rtc::SSLFingerprint> fingerprint;
if (!ParseFingerprintAttribute(line, &fingerprint, error)) {
return false;
}
session_td->identity_fingerprint = std::move(fingerprint);
} else if (HasAttribute(line, kAttributeSetup)) {
if (!ParseDtlsSetup(line, &(session_td->connection_role), error)) {
return false;
}
} else if (HasAttribute(line, kAttributeMsidSemantics)) {
std::string semantics;
if (!GetValue(line, kAttributeMsidSemantics, &semantics, error)) {
return false;
}
desc->set_msid_supported(
CaseInsensitiveFind(semantics, kMediaStreamSemantic));
} else if (HasAttribute(line, kAttributeExtmapAllowMixed)) {
desc->set_extmap_allow_mixed(true);
} else if (HasAttribute(line, kAttributeExtmap)) {
RtpExtension extmap;
if (!ParseExtmap(line, &extmap, error)) {
return false;
}
session_extmaps->push_back(extmap);
} else if (HasAttribute(line, kMediaTransportSettingLine)) {
std::string transport_name;
std::string transport_setting;
if (!ParseMediaTransportLine(line, &transport_name, &transport_setting,
error)) {
return false;
}
for (const auto& setting : desc->MediaTransportSettings()) {
if (setting.transport_name == transport_name) {
// Ignore repeated transport names rather than failing to parse so
// that in the future the same transport could have multiple configs.
RTC_LOG(INFO) << "x-mt line with repeated transport, transport_name="
<< transport_name;
return true;
}
}
desc->AddMediaTransportSetting(transport_name, transport_setting);
}
}
return true;
}
bool ParseGroupAttribute(const std::string& line,
cricket::SessionDescription* desc,
SdpParseError* error) {
RTC_DCHECK(desc != NULL);
// RFC 5888 and draft-holmberg-mmusic-sdp-bundle-negotiation-00
// a=group:BUNDLE video voice
std::vector<std::string> fields;
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar, &fields);
std::string semantics;
if (!GetValue(fields[0], kAttributeGroup, &semantics, error)) {
return false;
}
cricket::ContentGroup group(semantics);
for (size_t i = 1; i < fields.size(); ++i) {
group.AddContentName(fields[i]);
}
desc->AddGroup(group);
return true;
}
static bool ParseFingerprintAttribute(
const std::string& line,
std::unique_ptr<rtc::SSLFingerprint>* fingerprint,
SdpParseError* error) {
if (!IsLineType(line, kLineTypeAttributes) ||
!HasAttribute(line, kAttributeFingerprint)) {
return ParseFailedExpectLine(line, 0, kLineTypeAttributes,
kAttributeFingerprint, error);
}
std::vector<std::string> fields;
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar, &fields);
const size_t expected_fields = 2;
if (fields.size() != expected_fields) {
return ParseFailedExpectFieldNum(line, expected_fields, error);
}
// The first field here is "fingerprint:<hash>.
std::string algorithm;
if (!GetValue(fields[0], kAttributeFingerprint, &algorithm, error)) {
return false;
}
// Downcase the algorithm. Note that we don't need to downcase the
// fingerprint because hex_decode can handle upper-case.
absl::c_transform(algorithm, algorithm.begin(), ::tolower);
// The second field is the digest value. De-hexify it.
*fingerprint =
rtc::SSLFingerprint::CreateUniqueFromRfc4572(algorithm, fields[1]);
if (!*fingerprint) {
return ParseFailed(line, "Failed to create fingerprint from the digest.",
error);
}
return true;
}
static bool ParseDtlsSetup(const std::string& line,
cricket::ConnectionRole* role,
SdpParseError* error) {
// setup-attr = "a=setup:" role
// role = "active" / "passive" / "actpass" / "holdconn"
std::vector<std::string> fields;
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterColonChar, &fields);
const size_t expected_fields = 2;
if (fields.size() != expected_fields) {
return ParseFailedExpectFieldNum(line, expected_fields, error);
}
std::string role_str = fields[1];
if (!cricket::StringToConnectionRole(role_str, role)) {
return ParseFailed(line, "Invalid attribute value.", error);
}
return true;
}
static bool ParseMsidAttribute(const std::string& line,
std::vector<std::string>* stream_ids,
std::string* track_id,
SdpParseError* error) {
// https://datatracker.ietf.org/doc/draft-ietf-mmusic-msid/16/
// a=msid:<stream id> <track id>
// msid-value = msid-id [ SP msid-appdata ]
// msid-id = 1*64token-char ; see RFC 4566
// msid-appdata = 1*64token-char ; see RFC 4566
std::string field1;
std::string new_stream_id;
std::string new_track_id;
if (!rtc::tokenize_first(line.substr(kLinePrefixLength),
kSdpDelimiterSpaceChar, &field1, &new_track_id)) {
const size_t expected_fields = 2;
return ParseFailedExpectFieldNum(line, expected_fields, error);
}
if (new_track_id.empty()) {
return ParseFailed(line, "Missing track ID in msid attribute.", error);
}
// All track ids should be the same within an m section in a Unified Plan SDP.
if (!track_id->empty() && new_track_id.compare(*track_id) != 0) {
return ParseFailed(
line, "Two different track IDs in msid attribute in one m= section",
error);
}
*track_id = new_track_id;
// msid:<msid-id>
if (!GetValue(field1, kAttributeMsid, &new_stream_id, error)) {
return false;
}
if (new_stream_id.empty()) {
return ParseFailed(line, "Missing stream ID in msid attribute.", error);
}
// The special value "-" indicates "no MediaStream".
if (new_stream_id.compare(kNoStreamMsid) != 0) {
stream_ids->push_back(new_stream_id);
}
return true;
}
static void RemoveInvalidRidDescriptions(const std::vector<int>& payload_types,
std::vector<RidDescription>* rids) {
RTC_DCHECK(rids);
std::set<std::string> to_remove;
std::set<std::string> unique_rids;
// Check the rids to see which ones should be removed.
for (RidDescription& rid : *rids) {
// In the case of a duplicate, the entire "a=rid" line, and all "a=rid"
// lines with rid-ids that duplicate this line, are discarded and MUST NOT
// be included in the SDP Answer.
auto pair = unique_rids.insert(rid.rid);
// Insert will "fail" if element already exists.
if (!pair.second) {
to_remove.insert(rid.rid);
continue;
}
// If the "a=rid" line contains a "pt=", the list of payload types
// is verified against the list of valid payload types for the media
// section (that is, those listed on the "m=" line). Any PT missing
// from the "m=" line is discarded from the set of values in the
// "pt=". If no values are left in the "pt=" parameter after this
// processing, then the "a=rid" line is discarded.
if (rid.payload_types.empty()) {
// If formats were not specified, rid should not be removed.
continue;
}
// Note: Spec does not mention how to handle duplicate formats.
// Media section does not handle duplicates either.
std::set<int> removed_formats;
for (int payload_type : rid.payload_types) {
if (!absl::c_linear_search(payload_types, payload_type)) {
removed_formats.insert(payload_type);
}
}
rid.payload_types.erase(
std::remove_if(rid.payload_types.begin(), rid.payload_types.end(),
[&removed_formats](int format) {
return removed_formats.count(format) > 0;
}),
rid.payload_types.end());
// If all formats were removed then remove the rid alogether.
if (rid.payload_types.empty()) {
to_remove.insert(rid.rid);
}
}
// Remove every rid description that appears in the to_remove list.
if (!to_remove.empty()) {
rids->erase(std::remove_if(rids->begin(), rids->end(),
[&to_remove](const RidDescription& rid) {
return to_remove.count(rid.rid) > 0;
}),
rids->end());
}
}
// Create a new list (because SimulcastLayerList is immutable) without any
// layers that have a rid in the to_remove list.
// If a group of alternatives is empty after removing layers, the group should
// be removed altogether.
static SimulcastLayerList RemoveRidsFromSimulcastLayerList(
const std::set<std::string>& to_remove,
const SimulcastLayerList& layers) {
SimulcastLayerList result;
for (const std::vector<SimulcastLayer>& vector : layers) {