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webrtc_m130/pc/webrtc_sdp.cc
Dor Hen d1831cb4f8 Treat non DTLS/SCTP Protocol Based Data Channels as Unsupported Media 
In current state, the SDP parser in webrtc is not backward compatible with clients that might still be using RTP data channels.
Obviously, this isn't there is no such usecase in webrtc since the code is deleted, but in Meta we still use it and would like
to be able to negotiate between clients that offer RTP data channels.
Instead of erroring the parsing procedure, we can parse it as unsupported media in the client that no longer supports RTP data channels.

Replaced the existing test that expects parsing failures with a test that validates that the content was parsed as unsupported media.

Bug: webrtc:14872
Change-Id: I4c105cf55e33b8c19b2849e16148b8175053c40c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/291190
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39252}
2023-02-03 06:56:37 +00:00

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/*
* 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 <algorithm>
#include <cstddef>
#include <cstdint>
#include <map>
#include <memory>
#include <set>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
#include "absl/algorithm/container.h"
#include "absl/strings/ascii.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 "absl/strings/string_view.h"
#include "absl/types/optional.h"
#include "api/rtc_error.h"
#include "api/rtp_parameters.h"
#include "api/rtp_transceiver_direction.h"
#include "media/base/codec.h"
#include "media/base/media_constants.h"
#include "media/base/rid_description.h"
#include "media/base/rtp_utils.h"
#include "media/base/stream_params.h"
#include "media/sctp/sctp_transport_internal.h"
#include "p2p/base/candidate_pair_interface.h"
#include "p2p/base/ice_transport_internal.h"
#include "p2p/base/p2p_constants.h"
#include "p2p/base/port.h"
#include "p2p/base/port_interface.h"
#include "p2p/base/transport_description.h"
#include "p2p/base/transport_info.h"
#include "pc/media_protocol_names.h"
#include "pc/media_session.h"
#include "pc/sdp_serializer.h"
#include "pc/session_description.h"
#include "pc/simulcast_description.h"
#include "rtc_base/arraysize.h"
#include "rtc_base/checks.h"
#include "rtc_base/helpers.h"
#include "rtc_base/ip_address.h"
#include "rtc_base/logging.h"
#include "rtc_base/net_helper.h"
#include "rtc_base/network_constants.h"
#include "rtc_base/socket_address.h"
#include "rtc_base/ssl_fingerprint.h"
#include "rtc_base/string_encode.h"
#include "rtc_base/string_utils.h"
#include "rtc_base/strings/string_builder.h"
using cricket::AudioContentDescription;
using cricket::Candidate;
using cricket::Candidates;
using cricket::ContentInfo;
using cricket::CryptoParams;
using cricket::ICE_CANDIDATE_COMPONENT_RTCP;
using cricket::ICE_CANDIDATE_COMPONENT_RTP;
using cricket::kApplicationSpecificBandwidth;
using cricket::kCodecParamMaxPTime;
using cricket::kCodecParamMinPTime;
using cricket::kCodecParamPTime;
using cricket::kTransportSpecificBandwidth;
using cricket::MediaContentDescription;
using cricket::MediaProtocolType;
using cricket::MediaType;
using cricket::RidDescription;
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::UnsupportedContentDescription;
using cricket::VideoContentDescription;
using rtc::SocketAddress;
// 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.
// Check if passed character is a "token-char" from RFC 4566.
// https://datatracker.ietf.org/doc/html/rfc4566#section-9
// token-char = %x21 / %x23-27 / %x2A-2B / %x2D-2E / %x30-39
// / %x41-5A / %x5E-7E
bool IsTokenChar(char ch) {
return ch == 0x21 || (ch >= 0x23 && ch <= 0x27) || ch == 0x2a || ch == 0x2b ||
ch == 0x2d || ch == 0x2e || (ch >= 0x30 && ch <= 0x39) ||
(ch >= 0x41 && ch <= 0x5a) || (ch >= 0x5e && ch <= 0x7e);
}
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 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";
static const char kAttributePacketization[] = "packetization";
// Experimental flags
static const char kAttributeXGoogleFlag[] = "x-google-flag";
static const char kValueConference[] = "conference";
static const char kAttributeRtcpRemoteEstimate[] = "remote-net-estimate";
// 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 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";
static const char kDefaultSctpmapProtocol[] = "webrtc-datachannel";
// RTP payload type is in the 0-127 range. Use -1 to indicate "all" payload
// types.
const int kWildcardPayloadType = -1;
// Maximum number of channels allowed.
static const size_t kMaxNumberOfChannels = 24;
struct SsrcInfo {
uint32_t ssrc_id;
std::string cname;
std::string stream_id;
std::string track_id;
};
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 BuildMediaLine(const cricket::MediaType media_type,
const ContentInfo* content_info,
const MediaContentDescription* media_desc,
std::string* message);
static void BuildRtpContentAttributes(const MediaContentDescription* media_desc,
const cricket::MediaType media_type,
int msid_signaling,
std::string* message);
static void BuildRtpHeaderExtensions(const RtpHeaderExtensions& extensions,
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 BuildIceUfragPwd(const TransportInfo* transport_info,
std::string* message);
static void BuildDtlsFingerprintSetup(const TransportInfo* transport_info,
std::string* message);
static void BuildIceOptions(const std::vector<std::string>& transport_options,
std::string* message);
static bool ParseSessionDescription(absl::string_view 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 ParseMediaDescription(
absl::string_view 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(
absl::string_view message,
const cricket::MediaType media_type,
int mline_index,
absl::string_view 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 ParseGroupAttribute(absl::string_view line,
cricket::SessionDescription* desc,
SdpParseError* error);
static bool ParseSsrcAttribute(absl::string_view line,
SsrcInfoVec* ssrc_infos,
int* msid_signaling,
SdpParseError* error);
static bool ParseSsrcGroupAttribute(absl::string_view line,
SsrcGroupVec* ssrc_groups,
SdpParseError* error);
static bool ParseCryptoAttribute(absl::string_view line,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseRtpmapAttribute(absl::string_view line,
const cricket::MediaType media_type,
const std::vector<int>& payload_types,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseFmtpAttributes(absl::string_view line,
const cricket::MediaType media_type,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseFmtpParam(absl::string_view line,
std::string* parameter,
std::string* value,
SdpParseError* error);
static bool ParsePacketizationAttribute(absl::string_view line,
const cricket::MediaType media_type,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseRtcpFbAttribute(absl::string_view line,
const cricket::MediaType media_type,
MediaContentDescription* media_desc,
SdpParseError* error);
static bool ParseIceOptions(absl::string_view line,
std::vector<std::string>* transport_options,
SdpParseError* error);
static bool ParseExtmap(absl::string_view line,
RtpExtension* extmap,
SdpParseError* error);
static bool ParseFingerprintAttribute(
absl::string_view line,
std::unique_ptr<rtc::SSLFingerprint>* fingerprint,
SdpParseError* error);
static bool ParseDtlsSetup(absl::string_view line,
cricket::ConnectionRole* role,
SdpParseError* error);
static bool ParseMsidAttribute(absl::string_view 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(absl::string_view message,
size_t line_start,
std::string description,
SdpParseError* error) {
// Get the first line of `message` from `line_start`.
absl::string_view first_line;
size_t line_end = message.find(kNewLineChar, 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);
}
RTC_LOG(LS_ERROR) << "Failed to parse: \"" << first_line
<< "\". Reason: " << description;
if (error) {
// TODO(bugs.webrtc.org/13220): In C++17, we can use plain assignment, with
// a string_view on the right hand side.
error->line.assign(first_line.data(), first_line.size());
error->description = std::move(description);
}
return false;
}
// `line` is the failing line. The reason for the failure should be
// provided in the `description`.
static bool ParseFailed(absl::string_view line,
std::string description,
SdpParseError* error) {
return ParseFailed(line, 0, std::move(description), error);
}
// Parses failure where the failing SDP line isn't know or there are multiple
// failing lines.
static bool ParseFailed(std::string description, SdpParseError* error) {
return ParseFailed("", std::move(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(absl::string_view line,
int expected_fields,
SdpParseError* error) {
rtc::StringBuilder description;
description << "Expects " << expected_fields << " fields.";
return ParseFailed(line, description.Release(), 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(absl::string_view line,
int expected_min_fields,
SdpParseError* error) {
rtc::StringBuilder description;
description << "Expects at least " << expected_min_fields << " fields.";
return ParseFailed(line, description.Release(), 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(absl::string_view line,
absl::string_view attribute,
SdpParseError* error) {
rtc::StringBuilder description;
description << "Failed to get the value of attribute: " << attribute;
return ParseFailed(line, description.Release(), 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(absl::string_view message,
size_t line_start,
const char line_type,
absl::string_view line_value,
SdpParseError* error) {
rtc::StringBuilder description;
description << "Expect line: " << std::string(1, line_type) << "="
<< line_value;
return ParseFailed(message, line_start, description.Release(), error);
}
static bool AddLine(absl::string_view line, std::string* message) {
if (!message)
return false;
message->append(line.data(), line.size());
message->append(kLineBreak);
return true;
}
// Trim return character, if any.
static absl::string_view TrimReturnChar(absl::string_view line) {
if (!line.empty() && line.back() == kReturnChar) {
line.remove_suffix(1);
}
return line;
}
// Gets line of `message` starting at `pos`, and checks overall SDP syntax. On
// success, advances `pos` to the next line.
static absl::optional<absl::string_view> GetLine(absl::string_view message,
size_t* pos) {
size_t line_end = message.find(kNewLineChar, *pos);
if (line_end == absl::string_view::npos) {
return absl::nullopt;
}
absl::string_view line =
TrimReturnChar(message.substr(*pos, line_end - *pos));
// 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(static_cast<unsigned char>(line[0])) ||
line[1] != kSdpDelimiterEqualChar ||
(line[0] != kLineTypeSessionName && line[2] == kSdpDelimiterSpaceChar)) {
return absl::nullopt;
}
*pos = line_end + 1;
return line;
}
// Init `os` to "`type`=`value`".
static void InitLine(const char type,
absl::string_view value,
rtc::StringBuilder* os) {
os->Clear();
*os << std::string(1, type) << kSdpDelimiterEqual << value;
}
// Init `os` to "a=`attribute`".
static void InitAttrLine(absl::string_view attribute, rtc::StringBuilder* os) {
InitLine(kLineTypeAttributes, attribute, os);
}
// Writes a SDP attribute line based on `attribute` and `value` to `message`.
static void AddAttributeLine(absl::string_view attribute,
int value,
std::string* message) {
rtc::StringBuilder os;
InitAttrLine(attribute, &os);
os << kSdpDelimiterColon << value;
AddLine(os.str(), message);
}
static bool IsLineType(absl::string_view message,
const char type,
size_t line_start) {
if (message.size() < line_start + kLinePrefixLength) {
return false;
}
return (message[line_start] == type &&
message[line_start + 1] == kSdpDelimiterEqualChar);
}
static bool IsLineType(absl::string_view line, const char type) {
return IsLineType(line, type, 0);
}
static absl::optional<absl::string_view>
GetLineWithType(absl::string_view message, size_t* pos, const char type) {
if (IsLineType(message, type, *pos)) {
return GetLine(message, pos);
}
return absl::nullopt;
}
static bool HasAttribute(absl::string_view line, absl::string_view 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,
absl::string_view attribute,
absl::string_view 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(absl::string_view message,
absl::string_view 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() ||
absl::string_view(leftpart).compare(
leftpart.length() - attribute.length(), attribute.length(),
attribute) != 0) {
return ParseFailedGetValue(message, attribute, error);
}
return true;
}
// Get a single [token] from <attribute>:<token>
static bool GetSingleTokenValue(absl::string_view message,
absl::string_view attribute,
std::string* value,
SdpParseError* error) {
if (!GetValue(message, attribute, value, error)) {
return false;
}
if (!absl::c_all_of(absl::string_view(*value), IsTokenChar)) {
rtc::StringBuilder description;
description << "Illegal character found in the value of " << attribute;
return ParseFailed(message, description.Release(), 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(absl::string_view line,
absl::string_view s,
T* t,
SdpParseError* error) {
if (!rtc::FromString(s, t)) {
rtc::StringBuilder description;
description << "Invalid value: " << s << ".";
return ParseFailed(line, description.Release(), error);
}
return true;
}
static bool GetPayloadTypeFromString(absl::string_view line,
absl::string_view 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,
absl::string_view 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 = std::string(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,
absl::string_view msid_track_id,
StreamParamsVec* tracks,
int msid_signaling) {
RTC_DCHECK(tracks != NULL);
for (const SsrcInfo& ssrc_info : ssrc_infos) {
// According to https://tools.ietf.org/html/rfc5576#section-6.1, the CNAME
// attribute is mandatory, but we relax that restriction.
if (ssrc_info.cname.empty()) {
RTC_LOG(LS_WARNING) << "CNAME attribute missing for SSRC "
<< ssrc_info.ssrc_id;
}
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 = std::string(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 {
// 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(absl::string_view 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_DCHECK_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);
// BUNDLE Groups
std::vector<const cricket::ContentGroup*> groups =
desc->GetGroupsByName(cricket::GROUP_TYPE_BUNDLE);
for (const cricket::ContentGroup* group : groups) {
std::string group_line = kAttrGroup;
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(absl::string_view 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 = std::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(absl::string_view 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(absl::string_view transport_name,
absl::string_view 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(absl::string_view message,
Candidate* candidate,
SdpParseError* error,
bool is_raw) {
RTC_DCHECK(candidate != NULL);
// Makes sure `message` contains only one line.
absl::string_view first_line;
size_t line_end = message.find(kNewLineChar);
if (line_end == absl::string_view::npos) {
first_line = message;
} else if (line_end + 1 == message.size()) {
first_line = message.substr(0, line_end);
} else {
return ParseFailed(message, 0, "Expect one line only", error);
}
// Trim return char, if any.
first_line = TrimReturnChar(first_line);
// 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.Release(), error);
} else {
return ParseFailedExpectLine(first_line, 0, kLineTypeAttributes,
kAttributeCandidate, error);
}
}
std::vector<absl::string_view> fields =
rtc::split(candidate_value, kSdpDelimiterSpaceChar);
// 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 absl::string_view foundation = fields[0];
int component_id = 0;
if (!GetValueFromString(first_line, fields[1], &component_id, error)) {
return false;
}
const absl::string_view transport = fields[2];
uint32_t priority = 0;
if (!GetValueFromString(first_line, fields[3], &priority, error)) {
return false;
}
const absl::string_view 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);
absl::optional<cricket::ProtocolType> protocol =
cricket::StringToProto(transport);
if (!protocol) {
return ParseFailed(first_line, "Unsupported transport type.", error);
}
bool tcp_protocol = false;
switch (*protocol) {
// Supported protocols.
case cricket::PROTO_UDP:
break;
case cricket::PROTO_TCP:
case cricket::PROTO_SSLTCP:
tcp_protocol = true;
break;
default:
return ParseFailed(first_line, "Unsupported transport type.", error);
}
std::string candidate_type;
const absl::string_view 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.
absl::string_view 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 (!tcp_protocol) {
return ParseFailed(first_line, "Invalid non-TCP candidate", error);
}
} else if (tcp_protocol) {
// We allow the tcptype to be missing, for backwards compatibility,
// treating it as a passive candidate.
// TODO(bugs.webrtc.org/11466): Treat a missing tcptype as an error?
tcptype = cricket::TCPTYPE_PASSIVE_STR;
}
// 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.
absl::string_view username;
absl::string_view 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(absl::string_view line,
std::vector<std::string>* transport_options,
SdpParseError* error) {
std::string ice_options;
if (!GetValue(line, kAttributeIceOption, &ice_options, error)) {
return false;
}
std::vector<absl::string_view> fields =
rtc::split(ice_options, kSdpDelimiterSpaceChar);
for (size_t i = 0; i < fields.size(); ++i) {
transport_options->emplace_back(fields[i]);
}
return true;
}
bool ParseSctpPort(absl::string_view line,
int* sctp_port,
SdpParseError* error) {
// draft-ietf-mmusic-sctp-sdp-26
// a=sctp-port
const size_t expected_min_fields = 2;
std::vector<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterColonChar);
if (fields.size() < expected_min_fields) {
fields = rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
}
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(absl::string_view line,
int* max_message_size,
SdpParseError* error) {
// draft-ietf-mmusic-sctp-sdp-26
// a=max-message-size:199999
const size_t expected_min_fields = 2;
std::vector<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterColonChar);
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(absl::string_view line,
RtpExtension* extmap,
SdpParseError* error) {
// RFC 5285
// a=extmap:<value>["/"<direction>] <URI> <extensionattributes>
std::vector<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
const size_t expected_min_fields = 2;
if (fields.size() < expected_min_fields) {
return ParseFailedExpectMinFieldNum(line, expected_min_fields, error);
}
absl::string_view uri = fields[1];
std::string value_direction;
if (!GetValue(fields[0], kAttributeExtmap, &value_direction, error)) {
return false;
}
std::vector<absl::string_view> sub_fields =
rtc::split(value_direction, kSdpDelimiterSlashChar);
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 BuildIceUfragPwd(const TransportInfo* transport_info,
std::string* message) {
RTC_DCHECK(transport_info);
rtc::StringBuilder os;
// 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);
}
}
void BuildDtlsFingerprintSetup(const TransportInfo* transport_info,
std::string* message) {
RTC_DCHECK(transport_info);
rtc::StringBuilder os;
// RFC 4572
// fingerprint-attribute =
// "fingerprint" ":" hash-func SP fingerprint
// When using max-bundle this is already included at session level.
// Insert the fingerprint attribute.
auto fingerprint = transport_info->description.identity_fingerprint.get();
if (!fingerprint) {
return;
}
InitAttrLine(kAttributeFingerprint, &os);
os << kSdpDelimiterColon << fingerprint->algorithm << kSdpDelimiterSpace
<< fingerprint->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);
}
}
void BuildMediaLine(const cricket::MediaType media_type,
const ContentInfo* content_info,
const MediaContentDescription* media_desc,
std::string* message) {
rtc::StringBuilder os;
// RFC 4566
// m=<media> <port> <proto> <fmt>
// fmt is a list of payload type numbers that MAY be used in the session.
std::string type;
std::string fmt;
if (media_type == cricket::MEDIA_TYPE_VIDEO) {
type = kMediaTypeVideo;
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) {
type = kMediaTypeAudio;
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) {
type = kMediaTypeData;
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 {
RTC_DCHECK_NOTREACHED() << "Data description without SCTP";
}
} else if (media_type == cricket::MEDIA_TYPE_UNSUPPORTED) {
const UnsupportedContentDescription* unsupported_desc =
media_desc->as_unsupported();
type = unsupported_desc->media_type();
} else {
RTC_DCHECK_NOTREACHED();
}
// 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());
}
// Add the m and c lines.
InitLine(kLineTypeMedia, type, &os);
os << " " << port << " " << media_desc->protocol() << fmt;
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);
if (!content_info) {
return;
}
rtc::StringBuilder os;
const MediaContentDescription* media_desc = content_info->media_description();
RTC_DCHECK(media_desc);
// Add the m line.
BuildMediaLine(media_type, content_info, media_desc, message);
// Add the c line.
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 {
os << " " << kConnectionIpv4Addrtype << " " << kDummyAddress;
}
AddLine(os.str(), message);
// RFC 4566
// b=AS:<bandwidth> or
// b=TIAS:<bandwidth>
int bandwidth = media_desc->bandwidth();
std::string bandwidth_type = media_desc->bandwidth_type();
if (bandwidth_type == kApplicationSpecificBandwidth && bandwidth >= 1000) {
InitLine(kLineTypeSessionBandwidth, bandwidth_type, &os);
bandwidth /= 1000;
os << kSdpDelimiterColon << bandwidth;
AddLine(os.str(), message);
} else if (bandwidth_type == kTransportSpecificBandwidth && bandwidth > 0) {
InitLine(kLineTypeSessionBandwidth, bandwidth_type, &os);
os << kSdpDelimiterColon << bandwidth;
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, ice-pwd
// and DTLS fingerprint and setup attributes.
if (transport_info) {
BuildIceUfragPwd(transport_info, message);
// draft-petithuguenin-mmusic-ice-attributes-level-03
BuildIceOptions(transport_info->description.transport_options, message);
// Also include the DTLS fingerprint and setup attribute if available.
BuildDtlsFingerprintSetup(transport_info, 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);
}
BuildRtpHeaderExtensions(media_desc->rtp_header_extensions(), message);
// RFC 3264
// a=sendrecv || a=sendonly || a=sendrecv || a=inactive
switch (media_desc->direction()) {
// Special case that for sdp purposes should be treated same as inactive.
case RtpTransceiverDirection::kStopped:
case RtpTransceiverDirection::kInactive:
InitAttrLine(kAttributeInactive, &os);
break;
case RtpTransceiverDirection::kSendOnly:
InitAttrLine(kAttributeSendOnly, &os);
break;
case RtpTransceiverDirection::kRecvOnly:
InitAttrLine(kAttributeRecvOnly, &os);
break;
case RtpTransceiverDirection::kSendRecv:
InitAttrLine(kAttributeSendRecv, &os);
break;
default:
RTC_DCHECK_NOTREACHED();
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);
}
if (media_desc->remote_estimate()) {
InitAttrLine(kAttributeRtcpRemoteEstimate, &os);
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);
}
}
// 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);
}
}
for (const RidDescription& rid_description : media_desc->receive_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 BuildRtpHeaderExtensions(const RtpHeaderExtensions& extensions,
std::string* message) {
rtc::StringBuilder os;
// 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 (const RtpExtension& extension : extensions) {
InitAttrLine(kAttributeExtmap, &os);
os << kSdpDelimiterColon << extension.id;
if (extension.encrypt) {
os << kSdpDelimiterSpace << RtpExtension::kEncryptHeaderExtensionsUri;
}
os << kSdpDelimiterSpace << extension.uri;
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 WritePacketizationHeader(int payload_type, rtc::StringBuilder* os) {
// packetization header: a=packetization:`payload_type` <packetization_format>
// Add a=packetization
InitAttrLine(kAttributePacketization, 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(absl::string_view parameter_name,
absl::string_view parameter_value,
rtc::StringBuilder* os) {
if (parameter_name.empty()) {
// RFC 2198 and RFC 4733 don't use key-value pairs.
*os << parameter_value;
} else {
// fmtp parameters: `parameter_name`=`parameter_value`
*os << parameter_name << kSdpDelimiterEqual << parameter_value;
}
}
bool IsFmtpParam(absl::string_view 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;
}
bool WriteFmtpParameters(const cricket::CodecParameterMap& parameters,
rtc::StringBuilder* os) {
bool empty = true;
const char* delimiter = ""; // No delimiter before first parameter.
for (const auto& entry : parameters) {
const std::string& key = entry.first;
const std::string& value = entry.second;
if (IsFmtpParam(key)) {
*os << delimiter;
// A semicolon before each subsequent parameter.
delimiter = kSdpDelimiterSemicolon;
WriteFmtpParameter(key, value, os);
empty = false;
}
}
return !empty;
}
template <class T>
void AddFmtpLine(const T& codec, std::string* message) {
rtc::StringBuilder os;
WriteFmtpHeader(codec.id, &os);
os << kSdpDelimiterSpace;
// Create FMTP line and check that it's nonempty.
if (WriteFmtpParameters(codec.params, &os)) {
AddLine(os.str(), message);
}
return;
}
template <class T>
void AddPacketizationLine(const T& codec, std::string* message) {
if (!codec.packetization) {
return;
}
rtc::StringBuilder os;
WritePacketizationHeader(codec.id, &os);
os << " " << *codec.packetization;
AddLine(os.str(), message);
}
template <class T>
void AddRtcpFbLines(const T& codec, std::string* message) {
for (const auto& 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);
}
}
template <class T>
void AddWildcardRtcpFbLines(const std::vector<T>& codecs,
std::string* message) {
if (codecs.empty()) {
return;
}
for (const auto& param : codecs[0].feedback_params.params()) {
bool is_common_feedback = absl::c_all_of(codecs, [&param](const T& codec) {
// FEC mechanisms like RED, ulpfec and flexfec have empty feedback.
return codec.feedback_params.params().empty() ||
codec.feedback_params.Has(param);
});
if (is_common_feedback) {
rtc::StringBuilder os;
WriteRtcpFbHeader(kWildcardPayloadType, &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);
}
AddPacketizationLine(codec, message);
AddRtcpFbLines(codec, message);
AddFmtpLine(codec, message);
}
// rtcp-fb:* is added in addition to the per-codec feedback to allow
// downstream users time to upgrade their parsers.
AddWildcardRtcpFbLines(media_desc->as_video()->codecs(), 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);
}
}
// rtcp-fb:* is added in addition to the per-codec feedback to allow
// downstream users time to upgrade their parsers.
AddWildcardRtcpFbLines(media_desc->as_audio()->codecs(), message);
// 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_GE(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);
}
}
}
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_DCHECK_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() << " ";
}
// Note that we allow the tcptype to be missing, for backwards
// compatibility; the implementation treats this as a passive candidate.
// TODO(bugs.webrtc.org/11466): Treat a missing tcptype as an error?
if (candidate.protocol() == cricket::TCP_PROTOCOL_NAME &&
!candidate.tcptype().empty()) {
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(absl::string_view 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 ParseSessionDescription(absl::string_view 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) {
absl::optional<absl::string_view> line;
desc->set_msid_supported(false);
desc->set_extmap_allow_mixed(false);
// RFC 4566
// v= (protocol version)
line = GetLineWithType(message, pos, kLineTypeVersion);
if (!line) {
return ParseFailedExpectLine(message, *pos, kLineTypeVersion, std::string(),
error);
}
// RFC 4566
// o=<username> <sess-id> <sess-version> <nettype> <addrtype>
// <unicast-address>
line = GetLineWithType(message, pos, kLineTypeOrigin);
if (!line) {
return ParseFailedExpectLine(message, *pos, kLineTypeOrigin, std::string(),
error);
}
std::vector<absl::string_view> fields =
rtc::split(line->substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
const size_t expected_fields = 6;
if (fields.size() != expected_fields) {
return ParseFailedExpectFieldNum(*line, expected_fields, error);
}
*session_id = std::string(fields[1]);
*session_version = std::string(fields[2]);
// RFC 4566
// s= (session name)
line = GetLineWithType(message, pos, kLineTypeSessionName);
if (!line) {
return ParseFailedExpectLine(message, *pos, kLineTypeSessionName,
std::string(), error);
}
// optional lines
// Those are the optional lines, so shouldn't return false if not present.
// RFC 4566
// i=* (session information)
GetLineWithType(message, pos, kLineTypeSessionInfo);
// RFC 4566
// u=* (URI of description)
GetLineWithType(message, pos, kLineTypeSessionUri);
// RFC 4566
// e=* (email address)
GetLineWithType(message, pos, kLineTypeSessionEmail);
// RFC 4566
// p=* (phone number)
GetLineWithType(message, pos, kLineTypeSessionPhone);
// RFC 4566
// c=* (connection information -- not required if included in
// all media)
if (absl::optional<absl::string_view> cline =
GetLineWithType(message, pos, kLineTypeConnection);
cline.has_value()) {
if (!ParseConnectionData(*cline, connection_addr, error)) {
return false;
}
}
// RFC 4566
// b=* (zero or more bandwidth information lines)
while (GetLineWithType(message, pos, kLineTypeSessionBandwidth).has_value()) {
// 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, kLineTypeTiming).has_value()) {
return ParseFailedExpectLine(message, *pos, kLineTypeTiming, std::string(),
error);
}
while (GetLineWithType(message, pos, kLineTypeRepeatTimes).has_value()) {
// By pass zero or more r lines.
}
// Go through the rest of the time descriptions
while (GetLineWithType(message, pos, kLineTypeTiming).has_value()) {
while (GetLineWithType(message, pos, kLineTypeRepeatTimes).has_value()) {
// By pass zero or more r lines.
}
}
// RFC 4566
// z=* (time zone adjustments)
GetLineWithType(message, pos, kLineTypeTimeZone);
// RFC 4566
// k=* (encryption key)
GetLineWithType(message, pos, kLineTypeEncryptionKey);
// RFC 4566
// a=* (zero or more session attribute lines)
while (absl::optional<absl::string_view> aline =
GetLineWithType(message, pos, kLineTypeAttributes)) {
if (HasAttribute(*aline, kAttributeGroup)) {
if (!ParseGroupAttribute(*aline, desc, error)) {
return false;
}
} else if (HasAttribute(*aline, kAttributeIceUfrag)) {
if (!GetValue(*aline, kAttributeIceUfrag, &(session_td->ice_ufrag),
error)) {
return false;
}
} else if (HasAttribute(*aline, kAttributeIcePwd)) {
if (!GetValue(*aline, kAttributeIcePwd, &(session_td->ice_pwd), error)) {
return false;
}
} else if (HasAttribute(*aline, kAttributeIceLite)) {
session_td->ice_mode = cricket::ICEMODE_LITE;
} else if (HasAttribute(*aline, kAttributeIceOption)) {
if (!ParseIceOptions(*aline, &(session_td->transport_options), error)) {
return false;
}
} else if (HasAttribute(*aline, kAttributeFingerprint)) {
if (session_td->identity_fingerprint.get()) {
return ParseFailed(
*aline,
"Can't have multiple fingerprint attributes at the same level.",
error);
}
std::unique_ptr<rtc::SSLFingerprint> fingerprint;
if (!ParseFingerprintAttribute(*aline, &fingerprint, error)) {
return false;
}
session_td->identity_fingerprint = std::move(fingerprint);
} else if (HasAttribute(*aline, kAttributeSetup)) {
if (!ParseDtlsSetup(*aline, &(session_td->connection_role), error)) {
return false;
}
} else if (HasAttribute(*aline, kAttributeMsidSemantics)) {
std::string semantics;
if (!GetValue(*aline, kAttributeMsidSemantics, &semantics, error)) {
return false;
}
desc->set_msid_supported(
CaseInsensitiveFind(semantics, kMediaStreamSemantic));
} else if (HasAttribute(*aline, kAttributeExtmapAllowMixed)) {
desc->set_extmap_allow_mixed(true);
} else if (HasAttribute(*aline, kAttributeExtmap)) {
RtpExtension extmap;
if (!ParseExtmap(*aline, &extmap, error)) {
return false;
}
session_extmaps->push_back(extmap);
}
}
return true;
}
bool ParseGroupAttribute(absl::string_view 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<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
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(
absl::string_view line,
std::unique_ptr<rtc::SSLFingerprint>* fingerprint,
SdpParseError* error) {
std::vector<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
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(absl::string_view line,
cricket::ConnectionRole* role_ptr,
SdpParseError* error) {
// setup-attr = "a=setup:" role
// role = "active" / "passive" / "actpass" / "holdconn"
std::vector<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterColonChar);
const size_t expected_fields = 2;
if (fields.size() != expected_fields) {
return ParseFailedExpectFieldNum(line, expected_fields, error);
}
if (absl::optional<cricket::ConnectionRole> role =
cricket::StringToConnectionRole(fields[1]);
role.has_value()) {
*role_ptr = *role;
return true;
}
return ParseFailed(line, "Invalid attribute value.", error);
}
static bool ParseMsidAttribute(absl::string_view line,
std::vector<std::string>* stream_ids,
std::string* track_id,
SdpParseError* error) {
// https://datatracker.ietf.org/doc/rfc8830/
// a=msid:<msid-value>
// msid-value = msid-id [ SP msid-appdata ]
// msid-id = 1*64token-char ; see RFC 4566
// msid-appdata = 1*64token-char ; see RFC 4566
// Note that JSEP stipulates not sending msid-appdata so
// a=msid:<stream id> <track id>
// is supported for backward compability reasons only.
std::vector<std::string> fields;
size_t num_fields = rtc::tokenize(line.substr(kLinePrefixLength),
kSdpDelimiterSpaceChar, &fields);
if (num_fields < 1 || num_fields > 2) {
return ParseFailed(line, "Expected a stream ID and optionally a track ID",
error);
}
if (num_fields == 1) {
if (line.back() == kSdpDelimiterSpaceChar) {
return ParseFailed(line, "Missing track ID in msid attribute.", error);
}
if (!track_id->empty()) {
fields.push_back(*track_id);
} else {
// Ending with an empty string track will cause a random track id
// to be generated later in the process.
fields.push_back("");
}
}
RTC_DCHECK_EQ(fields.size(), 2);
// All track ids should be the same within an m section in a Unified Plan SDP.
if (!track_id->empty() && track_id->compare(fields[1]) != 0) {
return ParseFailed(
line, "Two different track IDs in msid attribute in one m= section",
error);
}
*track_id = fields[1];
// msid:<msid-id>
std::string new_stream_id;
if (!GetValue(fields[0], 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 &&
!absl::c_any_of(*stream_ids,
[&new_stream_id](const std::string& existing_stream_id) {
return new_stream_id == existing_stream_id;
})) {
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) {
std::vector<SimulcastLayer> new_layers;
for (const SimulcastLayer& layer : vector) {
if (to_remove.find(layer.rid) == to_remove.end()) {
new_layers.push_back(layer);
}
}
// If all layers were removed, do not add an entry.
if (!new_layers.empty()) {
result.AddLayerWithAlternatives(new_layers);
}
}
return result;
}
// Will remove Simulcast Layers if:
// 1. They appear in both send and receive directions.
// 2. They do not appear in the list of `valid_rids`.
static void RemoveInvalidRidsFromSimulcast(
const std::vector<RidDescription>& valid_rids,
SimulcastDescription* simulcast) {
RTC_DCHECK(simulcast);
std::set<std::string> to_remove;
std::vector<SimulcastLayer> all_send_layers =
simulcast->send_layers().GetAllLayers();
std::vector<SimulcastLayer> all_receive_layers =
simulcast->receive_layers().GetAllLayers();
// If a rid appears in both send and receive directions, remove it from both.
// This algorithm runs in O(n^2) time, but for small n (as is the case with
// simulcast layers) it should still perform well.
for (const SimulcastLayer& send_layer : all_send_layers) {
if (absl::c_any_of(all_receive_layers,
[&send_layer](const SimulcastLayer& layer) {
return layer.rid == send_layer.rid;
})) {
to_remove.insert(send_layer.rid);
}
}
// Add any rid that is not in the valid list to the remove set.
for (const SimulcastLayer& send_layer : all_send_layers) {
if (absl::c_none_of(valid_rids, [&send_layer](const RidDescription& rid) {
return send_layer.rid == rid.rid &&
rid.direction == cricket::RidDirection::kSend;
})) {
to_remove.insert(send_layer.rid);
}
}
// Add any rid that is not in the valid list to the remove set.
for (const SimulcastLayer& receive_layer : all_receive_layers) {
if (absl::c_none_of(
valid_rids, [&receive_layer](const RidDescription& rid) {
return receive_layer.rid == rid.rid &&
rid.direction == cricket::RidDirection::kReceive;
})) {
to_remove.insert(receive_layer.rid);
}
}
simulcast->send_layers() =
RemoveRidsFromSimulcastLayerList(to_remove, simulcast->send_layers());
simulcast->receive_layers() =
RemoveRidsFromSimulcastLayerList(to_remove, simulcast->receive_layers());
}
// RFC 3551
// PT encoding media type clock rate channels
// name (Hz)
// 0 PCMU A 8,000 1
// 1 reserved A
// 2 reserved A
// 3 GSM A 8,000 1
// 4 G723 A 8,000 1
// 5 DVI4 A 8,000 1
// 6 DVI4 A 16,000 1
// 7 LPC A 8,000 1
// 8 PCMA A 8,000 1
// 9 G722 A 8,000 1
// 10 L16 A 44,100 2
// 11 L16 A 44,100 1
// 12 QCELP A 8,000 1
// 13 CN A 8,000 1
// 14 MPA A 90,000 (see text)
// 15 G728 A 8,000 1
// 16 DVI4 A 11,025 1
// 17 DVI4 A 22,050 1
// 18 G729 A 8,000 1
struct StaticPayloadAudioCodec {
const char* name;
int clockrate;
size_t channels;
};
static const StaticPayloadAudioCodec kStaticPayloadAudioCodecs[] = {
{"PCMU", 8000, 1}, {"reserved", 0, 0}, {"reserved", 0, 0},
{"GSM", 8000, 1}, {"G723", 8000, 1}, {"DVI4", 8000, 1},
{"DVI4", 16000, 1}, {"LPC", 8000, 1}, {"PCMA", 8000, 1},
{"G722", 8000, 1}, {"L16", 44100, 2}, {"L16", 44100, 1},
{"QCELP", 8000, 1}, {"CN", 8000, 1}, {"MPA", 90000, 1},
{"G728", 8000, 1}, {"DVI4", 11025, 1}, {"DVI4", 22050, 1},
{"G729", 8000, 1},
};
void MaybeCreateStaticPayloadAudioCodecs(const std::vector<int>& fmts,
AudioContentDescription* media_desc) {
if (!media_desc) {
return;
}
RTC_DCHECK(media_desc->codecs().empty());
for (int payload_type : fmts) {
if (!media_desc->HasCodec(payload_type) && payload_type >= 0 &&
static_cast<uint32_t>(payload_type) <
arraysize(kStaticPayloadAudioCodecs)) {
std::string encoding_name = kStaticPayloadAudioCodecs[payload_type].name;
int clock_rate = kStaticPayloadAudioCodecs[payload_type].clockrate;
size_t channels = kStaticPayloadAudioCodecs[payload_type].channels;
media_desc->AddCodec(cricket::AudioCodec(payload_type, encoding_name,
clock_rate, 0, channels));
}
}
}
template <class C>
static std::unique_ptr<C> ParseContentDescription(
absl::string_view message,
const cricket::MediaType media_type,
int mline_index,
absl::string_view protocol,
const std::vector<int>& payload_types,
size_t* pos,
std::string* content_name,
bool* bundle_only,
int* msid_signaling,
TransportDescription* transport,
std::vector<std::unique_ptr<JsepIceCandidate>>* candidates,
webrtc::SdpParseError* error) {
auto media_desc = std::make_unique<C>();
media_desc->set_extmap_allow_mixed_enum(MediaContentDescription::kNo);
if (!ParseContent(message, media_type, mline_index, protocol, payload_types,
pos, content_name, bundle_only, msid_signaling,
media_desc.get(), transport, candidates, error)) {
return nullptr;
}
// Sort the codecs according to the m-line fmt list.
std::unordered_map<int, int> payload_type_preferences;
// "size + 1" so that the lowest preference payload type has a preference of
// 1, which is greater than the default (0) for payload types not in the fmt
// list.
int preference = static_cast<int>(payload_types.size() + 1);
for (int pt : payload_types) {
payload_type_preferences[pt] = preference--;
}
std::vector<typename C::CodecType> codecs = media_desc->codecs();
absl::c_sort(
codecs, [&payload_type_preferences](const typename C::CodecType& a,
const typename C::CodecType& b) {
return payload_type_preferences[a.id] > payload_type_preferences[b.id];
});
media_desc->set_codecs(codecs);
return media_desc;
}
bool ParseMediaDescription(
absl::string_view 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) {
RTC_DCHECK(desc != NULL);
int mline_index = -1;
int msid_signaling = 0;
// Zero or more media descriptions
// RFC 4566
// m=<media> <port> <proto> <fmt>
while (absl::optional<absl::string_view> mline =
GetLineWithType(message, pos, kLineTypeMedia)) {
++mline_index;
std::vector<absl::string_view> fields =
rtc::split(mline->substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
const size_t expected_min_fields = 4;
if (fields.size() < expected_min_fields) {
return ParseFailedExpectMinFieldNum(*mline, expected_min_fields, error);
}
bool port_rejected = false;
// RFC 3264
// To reject an offered stream, the port number in the corresponding stream
// in the answer MUST be set to zero.
if (fields[1] == kMediaPortRejected) {
port_rejected = true;
}
int port = 0;
if (!rtc::FromString<int>(fields[1], &port) || !IsValidPort(port)) {
return ParseFailed(*mline, "The port number is invalid", error);
}
absl::string_view protocol = fields[2];
// <fmt>
std::vector<int> payload_types;
if (cricket::IsRtpProtocol(protocol)) {
for (size_t j = 3; j < fields.size(); ++j) {
int pl = 0;
if (!GetPayloadTypeFromString(*mline, fields[j], &pl, error)) {
return false;
}
payload_types.push_back(pl);
}
}
// Make a temporary TransportDescription based on `session_td`.
// Some of this gets overwritten by ParseContent.
TransportDescription transport(
session_td.transport_options, session_td.ice_ufrag, session_td.ice_pwd,
session_td.ice_mode, session_td.connection_role,
session_td.identity_fingerprint.get());
std::unique_ptr<MediaContentDescription> content;
std::string content_name;
bool bundle_only = false;
int section_msid_signaling = 0;
absl::string_view media_type = fields[0];
if ((media_type == kMediaTypeVideo || media_type == kMediaTypeAudio) &&
!cricket::IsRtpProtocol(protocol)) {
return ParseFailed(*mline, "Unsupported protocol for media type", error);
}
if (media_type == kMediaTypeVideo) {
content = ParseContentDescription<VideoContentDescription>(
message, cricket::MEDIA_TYPE_VIDEO, mline_index, protocol,
payload_types, pos, &content_name, &bundle_only,
&section_msid_signaling, &transport, candidates, error);
} else if (media_type == kMediaTypeAudio) {
content = ParseContentDescription<AudioContentDescription>(
message, cricket::MEDIA_TYPE_AUDIO, mline_index, protocol,
payload_types, pos, &content_name, &bundle_only,
&section_msid_signaling, &transport, candidates, error);
} else if (media_type == kMediaTypeData && cricket::IsDtlsSctp(protocol)) {
// The draft-03 format is:
// m=application <port> DTLS/SCTP <sctp-port>...
// use_sctpmap should be false.
// The draft-26 format is:
// m=application <port> UDP/DTLS/SCTP webrtc-datachannel
// use_sctpmap should be false.
auto data_desc = std::make_unique<SctpDataContentDescription>();
// Default max message size is 64K
// according to draft-ietf-mmusic-sctp-sdp-26
data_desc->set_max_message_size(kDefaultSctpMaxMessageSize);
int p;
if (rtc::FromString(fields[3], &p)) {
data_desc->set_port(p);
} else if (fields[3] == kDefaultSctpmapProtocol) {
data_desc->set_use_sctpmap(false);
}
if (!ParseContent(message, cricket::MEDIA_TYPE_DATA, mline_index,
protocol, payload_types, pos, &content_name,
&bundle_only, &section_msid_signaling, data_desc.get(),
&transport, candidates, error)) {
return false;
}
data_desc->set_protocol(protocol);
content = std::move(data_desc);
} else {
RTC_LOG(LS_WARNING) << "Unsupported media type: " << *mline;
auto unsupported_desc =
std::make_unique<UnsupportedContentDescription>(media_type);
if (!ParseContent(message, cricket::MEDIA_TYPE_UNSUPPORTED, mline_index,
protocol, payload_types, pos, &content_name,
&bundle_only, &section_msid_signaling,
unsupported_desc.get(), &transport, candidates,
error)) {
return false;
}
unsupported_desc->set_protocol(protocol);
content = std::move(unsupported_desc);
}
if (!content.get()) {
// ParseContentDescription returns NULL if failed.
return false;
}
msid_signaling |= section_msid_signaling;
bool content_rejected = false;
// A port of 0 is not interpreted as a rejected m= section when it's
// used along with a=bundle-only.
if (bundle_only) {
if (!port_rejected) {
// Usage of bundle-only with a nonzero port is unspecified. So just
// ignore bundle-only if we see this.
bundle_only = false;
RTC_LOG(LS_WARNING)
<< "a=bundle-only attribute observed with a nonzero "
"port; this usage is unspecified so the attribute is being "
"ignored.";
}
} else {
// If not using bundle-only, interpret port 0 in the normal way; the m=
// section is being rejected.
content_rejected = port_rejected;
}
if (content->as_unsupported()) {
content_rejected = true;
} else if (cricket::IsRtpProtocol(protocol) && !content->as_sctp()) {
content->set_protocol(std::string(protocol));
// Set the extmap.
if (!session_extmaps.empty() &&
!content->rtp_header_extensions().empty()) {
return ParseFailed("",
"The a=extmap MUST be either all session level or "
"all media level.",
error);
}
for (size_t i = 0; i < session_extmaps.size(); ++i) {
content->AddRtpHeaderExtension(session_extmaps[i]);
}
} else if (content->as_sctp()) {
// Do nothing, it's OK
} else {
RTC_LOG(LS_WARNING) << "Parse failed with unknown protocol " << protocol;
return false;
}
// Use the session level connection address if the media level addresses are
// not specified.
rtc::SocketAddress address;
address = content->connection_address().IsNil()
? session_connection_addr
: content->connection_address();
address.SetPort(port);
content->set_connection_address(address);
desc->AddContent(content_name,
cricket::IsDtlsSctp(protocol) ? MediaProtocolType::kSctp
: MediaProtocolType::kRtp,
content_rejected, bundle_only, std::move(content));
// Create TransportInfo with the media level "ice-pwd" and "ice-ufrag".
desc->AddTransportInfo(TransportInfo(content_name, transport));
}
desc->set_msid_signaling(msid_signaling);
size_t end_of_message = message.size();
if (mline_index == -1 && *pos != end_of_message) {
ParseFailed(message, *pos, "Expects m line.", error);
return false;
}
return true;
}
bool VerifyCodec(const cricket::Codec& codec) {
// Codec has not been populated correctly unless the name has been set. This
// can happen if an SDP has an fmtp or rtcp-fb with a payload type but doesn't
// have a corresponding "rtpmap" line.
return !codec.name.empty();
}
bool VerifyAudioCodecs(const AudioContentDescription* audio_desc) {
return absl::c_all_of(audio_desc->codecs(), &VerifyCodec);
}
bool VerifyVideoCodecs(const VideoContentDescription* video_desc) {
return absl::c_all_of(video_desc->codecs(), &VerifyCodec);
}
void AddParameters(const cricket::CodecParameterMap& parameters,
cricket::Codec* codec) {
for (const auto& entry : parameters) {
const std::string& key = entry.first;
const std::string& value = entry.second;
codec->SetParam(key, value);
}
}
void AddFeedbackParameter(const cricket::FeedbackParam& feedback_param,
cricket::Codec* codec) {
codec->AddFeedbackParam(feedback_param);
}
void AddFeedbackParameters(const cricket::FeedbackParams& feedback_params,
cricket::Codec* codec) {
for (const cricket::FeedbackParam& param : feedback_params.params()) {
codec->AddFeedbackParam(param);
}
}
// Gets the current codec setting associated with `payload_type`. If there
// is no Codec associated with that payload type it returns an empty codec
// with that payload type.
template <class T>
T GetCodecWithPayloadType(const std::vector<T>& codecs, int payload_type) {
const T* codec = FindCodecById(codecs, payload_type);
if (codec)
return *codec;
// Return empty codec with `payload_type`.
T ret_val;
ret_val.id = payload_type;
return ret_val;
}
// Updates or creates a new codec entry in the media description.
template <class T, class U>
void AddOrReplaceCodec(MediaContentDescription* content_desc, const U& codec) {
T* desc = static_cast<T*>(content_desc);
std::vector<U> codecs = desc->codecs();
bool found = false;
for (U& existing_codec : codecs) {
if (codec.id == existing_codec.id) {
// Overwrite existing codec with the new codec.
existing_codec = codec;
found = true;
break;
}
}
if (!found) {
desc->AddCodec(codec);
return;
}
desc->set_codecs(codecs);
}
// Adds or updates existing codec corresponding to `payload_type` according
// to `parameters`.
template <class T, class U>
void UpdateCodec(MediaContentDescription* content_desc,
int payload_type,
const cricket::CodecParameterMap& parameters) {
// Codec might already have been populated (from rtpmap).
U new_codec = GetCodecWithPayloadType(static_cast<T*>(content_desc)->codecs(),
payload_type);
AddParameters(parameters, &new_codec);
AddOrReplaceCodec<T, U>(content_desc, new_codec);
}
// Adds or updates existing codec corresponding to `payload_type` according
// to `feedback_param`.
template <class T, class U>
void UpdateCodec(MediaContentDescription* content_desc,
int payload_type,
const cricket::FeedbackParam& feedback_param) {
// Codec might already have been populated (from rtpmap).
U new_codec = GetCodecWithPayloadType(static_cast<T*>(content_desc)->codecs(),
payload_type);
AddFeedbackParameter(feedback_param, &new_codec);
AddOrReplaceCodec<T, U>(content_desc, new_codec);
}
// Adds or updates existing video codec corresponding to `payload_type`
// according to `packetization`.
void UpdateVideoCodecPacketization(VideoContentDescription* video_desc,
int payload_type,
absl::string_view packetization) {
if (packetization != cricket::kPacketizationParamRaw) {
// Ignore unsupported packetization attribute.
return;
}
// Codec might already have been populated (from rtpmap).
cricket::VideoCodec codec =
GetCodecWithPayloadType(video_desc->codecs(), payload_type);
codec.packetization = std::string(packetization);
AddOrReplaceCodec<VideoContentDescription, cricket::VideoCodec>(video_desc,
codec);
}
template <class T>
bool PopWildcardCodec(std::vector<T>* codecs, T* wildcard_codec) {
for (auto iter = codecs->begin(); iter != codecs->end(); ++iter) {
if (iter->id == kWildcardPayloadType) {
*wildcard_codec = *iter;
codecs->erase(iter);
return true;
}
}
return false;
}
template <class T>
void UpdateFromWildcardCodecs(cricket::MediaContentDescriptionImpl<T>* desc) {
auto codecs = desc->codecs();
T wildcard_codec;
if (!PopWildcardCodec(&codecs, &wildcard_codec)) {
return;
}
for (auto& codec : codecs) {
AddFeedbackParameters(wildcard_codec.feedback_params, &codec);
}
desc->set_codecs(codecs);
}
void AddAudioAttribute(const std::string& name,
absl::string_view value,
AudioContentDescription* audio_desc) {
if (value.empty()) {
return;
}
std::vector<cricket::AudioCodec> codecs = audio_desc->codecs();
for (cricket::AudioCodec& codec : codecs) {
codec.params[name] = std::string(value);
}
audio_desc->set_codecs(codecs);
}
bool ParseContent(absl::string_view message,
const cricket::MediaType media_type,
int mline_index,
absl::string_view 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) {
RTC_DCHECK(media_desc != NULL);
RTC_DCHECK(content_name != NULL);
RTC_DCHECK(transport != NULL);
if (media_type == cricket::MEDIA_TYPE_AUDIO) {
MaybeCreateStaticPayloadAudioCodecs(payload_types, media_desc->as_audio());
}
// The media level "ice-ufrag" and "ice-pwd".
// The candidates before update the media level "ice-pwd" and "ice-ufrag".
Candidates candidates_orig;
std::string mline_id;
// Tracks created out of the ssrc attributes.
StreamParamsVec tracks;
SsrcInfoVec ssrc_infos;
SsrcGroupVec ssrc_groups;
std::string maxptime_as_string;
std::string ptime_as_string;
std::vector<std::string> stream_ids;
std::string track_id;
SdpSerializer deserializer;
std::vector<RidDescription> rids;
SimulcastDescription simulcast;
// Loop until the next m line
while (!IsLineType(message, kLineTypeMedia, *pos)) {
absl::optional<absl::string_view> line = GetLine(message, pos);
if (!line.has_value()) {
if (*pos >= message.size()) {
break; // Done parsing
} else {
return ParseFailed(message, *pos, "Invalid SDP line.", error);
}
}
// RFC 4566
// b=* (zero or more bandwidth information lines)
if (IsLineType(*line, kLineTypeSessionBandwidth)) {
std::string bandwidth;
std::string bandwidth_type;
if (!rtc::tokenize_first(line->substr(kLinePrefixLength),
kSdpDelimiterColonChar, &bandwidth_type,
&bandwidth)) {
return ParseFailed(
*line,
"b= syntax error, does not match b=<modifier>:<bandwidth-value>.",
error);
}
if (!(bandwidth_type == kApplicationSpecificBandwidth ||
bandwidth_type == kTransportSpecificBandwidth)) {
// Ignore unknown bandwidth types.
continue;
}
int b = 0;
if (!GetValueFromString(*line, bandwidth, &b, error)) {
return false;
}
// TODO(deadbeef): Historically, applications may be setting a value
// of -1 to mean "unset any previously set bandwidth limit", even
// though ommitting the "b=AS" entirely will do just that. Once we've
// transitioned applications to doing the right thing, it would be
// better to treat this as a hard error instead of just ignoring it.
if (bandwidth_type == kApplicationSpecificBandwidth && b == -1) {
RTC_LOG(LS_WARNING) << "Ignoring \"b=AS:-1\"; will be treated as \"no "
"bandwidth limit\".";
continue;
}
if (b < 0) {
return ParseFailed(
*line, "b=" + bandwidth_type + " value can't be negative.", error);
}
// Convert values. Prevent integer overflow.
if (bandwidth_type == kApplicationSpecificBandwidth) {
b = std::min(b, INT_MAX / 1000) * 1000;
} else {
b = std::min(b, INT_MAX);
}
media_desc->set_bandwidth(b);
media_desc->set_bandwidth_type(bandwidth_type);
continue;
}
// Parse the media level connection data.
if (IsLineType(*line, kLineTypeConnection)) {
rtc::SocketAddress addr;
if (!ParseConnectionData(*line, &addr, error)) {
return false;
}
media_desc->set_connection_address(addr);
continue;
}
if (!IsLineType(*line, kLineTypeAttributes)) {
// TODO(deadbeef): Handle other lines if needed.
RTC_LOG(LS_VERBOSE) << "Ignored line: " << *line;
continue;
}
// Handle attributes common to SCTP and RTP.
if (HasAttribute(*line, kAttributeMid)) {
// RFC 3388
// mid-attribute = "a=mid:" identification-tag
// identification-tag = token
// Use the mid identification-tag as the content name.
if (!GetSingleTokenValue(*line, kAttributeMid, &mline_id, error)) {
return false;
}
*content_name = mline_id;
} else if (HasAttribute(*line, kAttributeBundleOnly)) {
*bundle_only = true;
} else if (HasAttribute(*line, kAttributeCandidate)) {
Candidate candidate;
if (!ParseCandidate(*line, &candidate, error, false)) {
return false;
}
// ParseCandidate will parse non-standard ufrag and password attributes,
// since it's used for candidate trickling, but we only want to process
// the "a=ice-ufrag"/"a=ice-pwd" values in a session description, so
// strip them off at this point.
candidate.set_username(std::string());
candidate.set_password(std::string());
candidates_orig.push_back(candidate);
} else if (HasAttribute(*line, kAttributeIceUfrag)) {
if (!GetValue(*line, kAttributeIceUfrag, &transport->ice_ufrag, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeIcePwd)) {
if (!GetValue(*line, kAttributeIcePwd, &transport->ice_pwd, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeIceOption)) {
if (!ParseIceOptions(*line, &transport->transport_options, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeFmtp)) {
if (!ParseFmtpAttributes(*line, media_type, media_desc, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeFingerprint)) {
std::unique_ptr<rtc::SSLFingerprint> fingerprint;
if (!ParseFingerprintAttribute(*line, &fingerprint, error)) {
return false;
}
transport->identity_fingerprint = std::move(fingerprint);
} else if (HasAttribute(*line, kAttributeSetup)) {
if (!ParseDtlsSetup(*line, &(transport->connection_role), error)) {
return false;
}
} else if (cricket::IsDtlsSctp(protocol) &&
media_type == cricket::MEDIA_TYPE_DATA) {
//
// SCTP specific attributes
//
if (HasAttribute(*line, kAttributeSctpPort)) {
if (media_desc->as_sctp()->use_sctpmap()) {
return ParseFailed(
*line, "sctp-port attribute can't be used with sctpmap.", error);
}
int sctp_port;
if (!ParseSctpPort(*line, &sctp_port, error)) {
return false;
}
media_desc->as_sctp()->set_port(sctp_port);
} else if (HasAttribute(*line, kAttributeMaxMessageSize)) {
int max_message_size;
if (!ParseSctpMaxMessageSize(*line, &max_message_size, error)) {
return false;
}
media_desc->as_sctp()->set_max_message_size(max_message_size);
} else if (HasAttribute(*line, kAttributeSctpmap)) {
// Ignore a=sctpmap: from early versions of draft-ietf-mmusic-sctp-sdp
continue;
}
} else if (cricket::IsRtpProtocol(protocol)) {
//
// RTP specific attributes
//
if (HasAttribute(*line, kAttributeRtcpMux)) {
media_desc->set_rtcp_mux(true);
} else if (HasAttribute(*line, kAttributeRtcpReducedSize)) {
media_desc->set_rtcp_reduced_size(true);
} else if (HasAttribute(*line, kAttributeRtcpRemoteEstimate)) {
media_desc->set_remote_estimate(true);
} else if (HasAttribute(*line, kAttributeSsrcGroup)) {
if (!ParseSsrcGroupAttribute(*line, &ssrc_groups, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeSsrc)) {
if (!ParseSsrcAttribute(*line, &ssrc_infos, msid_signaling, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeCrypto)) {
if (!ParseCryptoAttribute(*line, media_desc, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeRtpmap)) {
if (!ParseRtpmapAttribute(*line, media_type, payload_types, media_desc,
error)) {
return false;
}
} else if (HasAttribute(*line, kCodecParamMaxPTime)) {
if (!GetValue(*line, kCodecParamMaxPTime, &maxptime_as_string, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributePacketization)) {
if (!ParsePacketizationAttribute(*line, media_type, media_desc,
error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeRtcpFb)) {
if (!ParseRtcpFbAttribute(*line, media_type, media_desc, error)) {
return false;
}
} else if (HasAttribute(*line, kCodecParamPTime)) {
if (!GetValue(*line, kCodecParamPTime, &ptime_as_string, error)) {
return false;
}
} else if (HasAttribute(*line, kAttributeSendOnly)) {
media_desc->set_direction(RtpTransceiverDirection::kSendOnly);
} else if (HasAttribute(*line, kAttributeRecvOnly)) {
media_desc->set_direction(RtpTransceiverDirection::kRecvOnly);
} else if (HasAttribute(*line, kAttributeInactive)) {
media_desc->set_direction(RtpTransceiverDirection::kInactive);
} else if (HasAttribute(*line, kAttributeSendRecv)) {
media_desc->set_direction(RtpTransceiverDirection::kSendRecv);
} else if (HasAttribute(*line, kAttributeExtmapAllowMixed)) {
media_desc->set_extmap_allow_mixed_enum(
MediaContentDescription::kMedia);
} else if (HasAttribute(*line, kAttributeExtmap)) {
RtpExtension extmap;
if (!ParseExtmap(*line, &extmap, error)) {
return false;
}
media_desc->AddRtpHeaderExtension(extmap);
} else if (HasAttribute(*line, kAttributeXGoogleFlag)) {
// Experimental attribute. Conference mode activates more aggressive
// AEC and NS settings.
// TODO(deadbeef): expose API to set these directly.
std::string flag_value;
if (!GetValue(*line, kAttributeXGoogleFlag, &flag_value, error)) {
return false;
}
if (flag_value.compare(kValueConference) == 0)
media_desc->set_conference_mode(true);
} else if (HasAttribute(*line, kAttributeMsid)) {
if (!ParseMsidAttribute(*line, &stream_ids, &track_id, error)) {
return false;
}
*msid_signaling |= cricket::kMsidSignalingMediaSection;
} else if (HasAttribute(*line, kAttributeRid)) {
const size_t kRidPrefixLength =
kLinePrefixLength + arraysize(kAttributeRid);
if (line->size() <= kRidPrefixLength) {
RTC_LOG(LS_INFO) << "Ignoring empty RID attribute: " << *line;
continue;
}
RTCErrorOr<RidDescription> error_or_rid_description =
deserializer.DeserializeRidDescription(
line->substr(kRidPrefixLength));
// Malformed a=rid lines are discarded.
if (!error_or_rid_description.ok()) {
RTC_LOG(LS_INFO) << "Ignoring malformed RID line: '" << *line
<< "'. Error: "
<< error_or_rid_description.error().message();
continue;
}
rids.push_back(error_or_rid_description.MoveValue());
} else if (HasAttribute(*line, kAttributeSimulcast)) {
const size_t kSimulcastPrefixLength =
kLinePrefixLength + arraysize(kAttributeSimulcast);
if (line->size() <= kSimulcastPrefixLength) {
return ParseFailed(*line, "Simulcast attribute is empty.", error);
}
if (!simulcast.empty()) {
return ParseFailed(*line, "Multiple Simulcast attributes specified.",
error);
}
RTCErrorOr<SimulcastDescription> error_or_simulcast =
deserializer.DeserializeSimulcastDescription(
line->substr(kSimulcastPrefixLength));
if (!error_or_simulcast.ok()) {
return ParseFailed(*line,
std::string("Malformed simulcast line: ") +
error_or_simulcast.error().message(),
error);
}
simulcast = error_or_simulcast.value();
} else if (HasAttribute(*line, kAttributeRtcp)) {
// Ignore and do not log a=rtcp line.
// JSEP section 5.8.2 (media section parsing) says to ignore it.
continue;
} else {
// Unrecognized attribute in RTP protocol.
RTC_LOG(LS_VERBOSE) << "Ignored line: " << *line;
continue;
}
} else {
// Only parse lines that we are interested of.
RTC_LOG(LS_VERBOSE) << "Ignored line: " << *line;
continue;
}
}
// Remove duplicate or inconsistent rids.
RemoveInvalidRidDescriptions(payload_types, &rids);
// If simulcast is specifed, split the rids into send and receive.
// Rids that do not appear in simulcast attribute will be removed.
std::vector<RidDescription> send_rids;
std::vector<RidDescription> receive_rids;
if (!simulcast.empty()) {
// Verify that the rids in simulcast match rids in sdp.
RemoveInvalidRidsFromSimulcast(rids, &simulcast);
// Use simulcast description to figure out Send / Receive RIDs.
std::map<std::string, RidDescription> rid_map;
for (const RidDescription& rid : rids) {
rid_map[rid.rid] = rid;
}
for (const auto& layer : simulcast.send_layers().GetAllLayers()) {
auto iter = rid_map.find(layer.rid);
RTC_DCHECK(iter != rid_map.end());
send_rids.push_back(iter->second);
}
for (const auto& layer : simulcast.receive_layers().GetAllLayers()) {
auto iter = rid_map.find(layer.rid);
RTC_DCHECK(iter != rid_map.end());
receive_rids.push_back(iter->second);
}
media_desc->set_simulcast_description(simulcast);
} else {
// RID is specified in RFC 8851, which identifies a lot of usages.
// We only support RFC 8853 usage of RID, not anything else.
// Ignore all RID parameters when a=simulcast is missing.
// In particular do NOT do send_rids = rids;
RTC_LOG(LS_VERBOSE) << "Ignoring send_rids without simulcast";
}
media_desc->set_receive_rids(receive_rids);
// Create tracks from the `ssrc_infos`.
// If the stream_id/track_id for all SSRCS are identical, one StreamParams
// will be created in CreateTracksFromSsrcInfos, containing all the SSRCs from
// the m= section.
if (!ssrc_infos.empty()) {
CreateTracksFromSsrcInfos(ssrc_infos, stream_ids, track_id, &tracks,
*msid_signaling);
} else if (media_type != cricket::MEDIA_TYPE_DATA &&
(*msid_signaling & cricket::kMsidSignalingMediaSection)) {
// If the stream_ids/track_id was signaled but SSRCs were unsignaled we
// still create a track. This isn't done for data media types because
// StreamParams aren't used for SCTP streams, and RTP data channels don't
// support unsignaled SSRCs.
// If track id was not specified, create a random one.
if (track_id.empty()) {
track_id = rtc::CreateRandomString(8);
}
CreateTrackWithNoSsrcs(stream_ids, track_id, send_rids, &tracks);
}
// Add the ssrc group to the track.
for (const SsrcGroup& ssrc_group : ssrc_groups) {
if (ssrc_group.ssrcs.empty()) {
continue;
}
uint32_t ssrc = ssrc_group.ssrcs.front();
for (StreamParams& track : tracks) {
if (track.has_ssrc(ssrc)) {
track.ssrc_groups.push_back(ssrc_group);
}
}
}
// Add the new tracks to the `media_desc`.
for (StreamParams& track : tracks) {
media_desc->AddStream(track);
}
if (media_type == cricket::MEDIA_TYPE_AUDIO) {
AudioContentDescription* audio_desc = media_desc->as_audio();
UpdateFromWildcardCodecs(audio_desc);
// Verify audio codec ensures that no audio codec has been populated with
// only fmtp.
if (!VerifyAudioCodecs(audio_desc)) {
return ParseFailed("Failed to parse audio codecs correctly.", error);
}
AddAudioAttribute(kCodecParamMaxPTime, maxptime_as_string, audio_desc);
AddAudioAttribute(kCodecParamPTime, ptime_as_string, audio_desc);
}
if (media_type == cricket::MEDIA_TYPE_VIDEO) {
VideoContentDescription* video_desc = media_desc->as_video();
UpdateFromWildcardCodecs(video_desc);
// Verify video codec ensures that no video codec has been populated with
// only rtcp-fb.
if (!VerifyVideoCodecs(video_desc)) {
return ParseFailed("Failed to parse video codecs correctly.", error);
}
}
// RFC 5245
// Update the candidates with the media level "ice-pwd" and "ice-ufrag".
for (Candidate& candidate : candidates_orig) {
RTC_DCHECK(candidate.username().empty() ||
candidate.username() == transport->ice_ufrag);
candidate.set_username(transport->ice_ufrag);
RTC_DCHECK(candidate.password().empty());
candidate.set_password(transport->ice_pwd);
candidates->push_back(
std::make_unique<JsepIceCandidate>(mline_id, mline_index, candidate));
}
return true;
}
bool ParseSsrcAttribute(absl::string_view line,
SsrcInfoVec* ssrc_infos,
int* msid_signaling,
SdpParseError* error) {
RTC_DCHECK(ssrc_infos != NULL);
// RFC 5576
// a=ssrc:<ssrc-id> <attribute>
// a=ssrc:<ssrc-id> <attribute>:<value>
std::string field1, field2;
if (!rtc::tokenize_first(line.substr(kLinePrefixLength),
kSdpDelimiterSpaceChar, &field1, &field2)) {
const size_t expected_fields = 2;
return ParseFailedExpectFieldNum(line, expected_fields, error);
}
// ssrc:<ssrc-id>
std::string ssrc_id_s;
if (!GetValue(field1, kAttributeSsrc, &ssrc_id_s, error)) {
return false;
}
uint32_t ssrc_id = 0;
if (!GetValueFromString(line, ssrc_id_s, &ssrc_id, error)) {
return false;
}
std::string attribute;
std::string value;
if (!rtc::tokenize_first(field2, kSdpDelimiterColonChar, &attribute,
&value)) {
rtc::StringBuilder description;
description << "Failed to get the ssrc attribute value from " << field2
<< ". Expected format <attribute>:<value>.";
return ParseFailed(line, description.Release(), error);
}
// Check if there's already an item for this `ssrc_id`. Create a new one if
// there isn't.
auto ssrc_info_it =
absl::c_find_if(*ssrc_infos, [ssrc_id](const SsrcInfo& ssrc_info) {
return ssrc_info.ssrc_id == ssrc_id;
});
if (ssrc_info_it == ssrc_infos->end()) {
SsrcInfo info;
info.ssrc_id = ssrc_id;
ssrc_infos->push_back(info);
ssrc_info_it = ssrc_infos->end() - 1;
}
SsrcInfo& ssrc_info = *ssrc_info_it;
// Store the info to the `ssrc_info`.
if (attribute == kSsrcAttributeCname) {
// RFC 5576
// cname:<value>
ssrc_info.cname = value;
} else if (attribute == kSsrcAttributeMsid) {
// draft-alvestrand-mmusic-msid-00
// msid:identifier [appdata]
std::vector<absl::string_view> fields =
rtc::split(value, kSdpDelimiterSpaceChar);
if (fields.size() < 1 || fields.size() > 2) {
return ParseFailed(
line, "Expected format \"msid:<identifier>[ <appdata>]\".", error);
}
ssrc_info.stream_id = std::string(fields[0]);
if (fields.size() == 2) {
ssrc_info.track_id = std::string(fields[1]);
}
*msid_signaling |= cricket::kMsidSignalingSsrcAttribute;
} else {
RTC_LOG(LS_INFO) << "Ignored unknown ssrc-specific attribute: " << line;
}
return true;
}
bool ParseSsrcGroupAttribute(absl::string_view line,
SsrcGroupVec* ssrc_groups,
SdpParseError* error) {
RTC_DCHECK(ssrc_groups != NULL);
// RFC 5576
// a=ssrc-group:<semantics> <ssrc-id> ...
std::vector<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
const size_t expected_min_fields = 2;
if (fields.size() < expected_min_fields) {
return ParseFailedExpectMinFieldNum(line, expected_min_fields, error);
}
std::string semantics;
if (!GetValue(fields[0], kAttributeSsrcGroup, &semantics, error)) {
return false;
}
std::vector<uint32_t> ssrcs;
for (size_t i = 1; i < fields.size(); ++i) {
uint32_t ssrc = 0;
if (!GetValueFromString(line, fields[i], &ssrc, error)) {
return false;
}
ssrcs.push_back(ssrc);
}
ssrc_groups->push_back(SsrcGroup(semantics, ssrcs));
return true;
}
bool ParseCryptoAttribute(absl::string_view line,
MediaContentDescription* media_desc,
SdpParseError* error) {
std::vector<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
// RFC 4568
// a=crypto:<tag> <crypto-suite> <key-params> [<session-params>]
const size_t expected_min_fields = 3;
if (fields.size() < expected_min_fields) {
return ParseFailedExpectMinFieldNum(line, expected_min_fields, error);
}
std::string tag_value;
if (!GetValue(fields[0], kAttributeCrypto, &tag_value, error)) {
return false;
}
int tag = 0;
if (!GetValueFromString(line, tag_value, &tag, error)) {
return false;
}
const absl::string_view crypto_suite = fields[1];
const absl::string_view key_params = fields[2];
absl::string_view session_params;
if (fields.size() > 3) {
session_params = fields[3];
}
media_desc->AddCrypto(
CryptoParams(tag, crypto_suite, key_params, session_params));
return true;
}
// Updates or creates a new codec entry in the audio description with according
// to `name`, `clockrate`, `bitrate`, and `channels`.
void UpdateCodec(int payload_type,
absl::string_view name,
int clockrate,
int bitrate,
size_t channels,
AudioContentDescription* audio_desc) {
// Codec may already be populated with (only) optional parameters
// (from an fmtp).
cricket::AudioCodec codec =
GetCodecWithPayloadType(audio_desc->codecs(), payload_type);
codec.name = std::string(name);
codec.clockrate = clockrate;
codec.bitrate = bitrate;
codec.channels = channels;
AddOrReplaceCodec<AudioContentDescription, cricket::AudioCodec>(audio_desc,
codec);
}
// Updates or creates a new codec entry in the video description according to
// `name`, `width`, `height`, and `framerate`.
void UpdateCodec(int payload_type,
absl::string_view name,
VideoContentDescription* video_desc) {
// Codec may already be populated with (only) optional parameters
// (from an fmtp).
cricket::VideoCodec codec =
GetCodecWithPayloadType(video_desc->codecs(), payload_type);
codec.name = std::string(name);
AddOrReplaceCodec<VideoContentDescription, cricket::VideoCodec>(video_desc,
codec);
}
bool ParseRtpmapAttribute(absl::string_view line,
const cricket::MediaType media_type,
const std::vector<int>& payload_types,
MediaContentDescription* media_desc,
SdpParseError* error) {
static const int kFirstDynamicPayloadTypeLowerRange = 35;
std::vector<absl::string_view> fields =
rtc::split(line.substr(kLinePrefixLength), kSdpDelimiterSpaceChar);
// RFC 4566
// a=rtpmap:<payload type> <encoding name>/<clock rate>[/<encodingparameters>]
const size_t expected_min_fields = 2;
if (fields.size() < expected_min_fields) {
return ParseFailedExpectMinFieldNum(line, expected_min_fields, error);
}
std::string payload_type_value;
if (!GetValue(fields[0], kAttributeRtpmap, &payload_type_value, error)) {
return false;
}
int payload_type = 0;
if (!GetPayloadTypeFromString(line, payload_type_value, &payload_type,
error)) {
return false;
}
if (!absl::c_linear_search(payload_types, payload_type)) {
RTC_LOG(LS_WARNING) << "Ignore rtpmap line that did not appear in the "
"<fmt> of the m-line: "
<< line;
return true;
}
std::vector<absl::string_view> codec_params = rtc::split(fields[1], '/');
// <encoding name>/<clock rate>[/<encodingparameters>]
// 2 mandatory fields
if (codec_params.size() < 2 || codec_params.size() > 3) {
return ParseFailed(line,
"Expected format \"<encoding name>/<clock rate>"
"[/<encodingparameters>]\".",
error);
}
const absl::string_view encoding_name = codec_params[0];
int clock_rate = 0;
if (!GetValueFromString(line, codec_params[1], &clock_rate, error)) {
return false;
}
if (media_type == cricket::MEDIA_TYPE_VIDEO) {
VideoContentDescription* video_desc = media_desc->as_video();
for (const cricket::VideoCodec& existing_codec : video_desc->codecs()) {
if (!existing_codec.name.empty() && payload_type == existing_codec.id &&
(!absl::EqualsIgnoreCase(encoding_name, existing_codec.name) ||
clock_rate != existing_codec.clockrate)) {
rtc::StringBuilder description;
description
<< "Duplicate "
<< (payload_type < kFirstDynamicPayloadTypeLowerRange
? "statically assigned"
: "")
<< " payload type with conflicting codec name or clock rate.";
return ParseFailed(line, description.Release(), error);
}
}
UpdateCodec(payload_type, encoding_name, video_desc);
} else if (media_type == cricket::MEDIA_TYPE_AUDIO) {
// RFC 4566
// For audio streams, <encoding parameters> indicates the number
// of audio channels. This parameter is OPTIONAL and may be
// omitted if the number of channels is one, provided that no
// additional parameters are needed.
size_t channels = 1;
if (codec_params.size() == 3) {
if (!GetValueFromString(line, codec_params[2], &channels, error)) {
return false;
}
}
if (channels > kMaxNumberOfChannels) {
return ParseFailed(line, "At most 24 channels are supported.", error);
}
AudioContentDescription* audio_desc = media_desc->as_audio();
for (const cricket::AudioCodec& existing_codec : audio_desc->codecs()) {
// TODO(crbug.com/1338902) re-add checks for clockrate and number of
// channels.
if (!existing_codec.name.empty() && payload_type == existing_codec.id &&
(!absl::EqualsIgnoreCase(encoding_name, existing_codec.name))) {
rtc::StringBuilder description;
description
<< "Duplicate "
<< (payload_type < kFirstDynamicPayloadTypeLowerRange
? "statically assigned"
: "")
<< " payload type with conflicting codec name or clock rate.";
return ParseFailed(line, description.Release(), error);
}
}
UpdateCodec(payload_type, encoding_name, clock_rate, 0, channels,
audio_desc);
}
return true;
}
bool ParseFmtpParam(absl::string_view line,
std::string* parameter,
std::string* value,
SdpParseError* error) {
if (!rtc::tokenize_first(line, kSdpDelimiterEqualChar, parameter, value)) {
// Support for non-key-value lines like RFC 2198 or RFC 4733.
*parameter = "";
*value = std::string(line);
return true;
}
// a=fmtp:<payload_type> <param1>=<value1>; <param2>=<value2>; ...
return true;
}
bool ParseFmtpAttributes(absl::string_view line,
const cricket::MediaType media_type,
MediaContentDescription* media_desc,
SdpParseError* error) {
if (media_type != cricket::MEDIA_TYPE_AUDIO &&
media_type != cricket::MEDIA_TYPE_VIDEO) {
return true;
}
std::string line_payload;
std::string line_params;
// https://tools.ietf.org/html/rfc4566#section-6
// a=fmtp:<format> <format specific parameters>
// At least two fields, whereas the second one is any of the optional
// parameters.
if (!rtc::tokenize_first(line.substr(kLinePrefixLength),
kSdpDelimiterSpaceChar, &line_payload,
&line_params)) {
ParseFailedExpectMinFieldNum(line, 2, error);
return false;
}
// Parse out the payload information.
std::string payload_type_str;
if (!GetValue(line_payload, kAttributeFmtp, &payload_type_str, error)) {
return false;
}
int payload_type = 0;
if (!GetPayloadTypeFromString(line_payload, payload_type_str, &payload_type,
error)) {
return false;
}
// Parse out format specific parameters.
cricket::CodecParameterMap codec_params;
for (absl::string_view param :
rtc::split(line_params, kSdpDelimiterSemicolonChar)) {
std::string name;
std::string value;
if (!ParseFmtpParam(absl::StripAsciiWhitespace(param), &name, &value,
error)) {
return false;
}
if (codec_params.find(name) != codec_params.end()) {
RTC_LOG(LS_INFO) << "Overwriting duplicate fmtp parameter with key \""
<< name << "\".";
}
codec_params[name] = value;
}
if (media_type == cricket::MEDIA_TYPE_AUDIO) {
UpdateCodec<AudioContentDescription, cricket::AudioCodec>(
media_desc, payload_type, codec_params);
} else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
UpdateCodec<VideoContentDescription, cricket::VideoCodec>(
media_desc, payload_type, codec_params);
}
return true;
}
bool ParsePacketizationAttribute(absl::string_view line,
const cricket::MediaType media_type,
MediaContentDescription* media_desc,
SdpParseError* error) {
if (media_type != cricket::MEDIA_TYPE_VIDEO) {
return true;
}
std::vector<absl::string_view> packetization_fields =
rtc::split(line, kSdpDelimiterSpaceChar);
if (packetization_fields.size() < 2) {
return ParseFailedGetValue(line, kAttributePacketization, error);
}
std::string payload_type_string;
if (!GetValue(packetization_fields[0], kAttributePacketization,
&payload_type_string, error)) {
return false;
}
int payload_type;
if (!GetPayloadTypeFromString(line, payload_type_string, &payload_type,
error)) {
return false;
}
absl::string_view packetization = packetization_fields[1];
UpdateVideoCodecPacketization(media_desc->as_video(), payload_type,
packetization);
return true;
}
bool ParseRtcpFbAttribute(absl::string_view line,
const cricket::MediaType media_type,
MediaContentDescription* media_desc,
SdpParseError* error) {
if (media_type != cricket::MEDIA_TYPE_AUDIO &&
media_type != cricket::MEDIA_TYPE_VIDEO) {
return true;
}
std::vector<absl::string_view> rtcp_fb_fields =
rtc::split(line, kSdpDelimiterSpaceChar);
if (rtcp_fb_fields.size() < 2) {
return ParseFailedGetValue(line, kAttributeRtcpFb, error);
}
std::string payload_type_string;
if (!GetValue(rtcp_fb_fields[0], kAttributeRtcpFb, &payload_type_string,
error)) {
return false;
}
int payload_type = kWildcardPayloadType;
if (payload_type_string != "*") {
if (!GetPayloadTypeFromString(line, payload_type_string, &payload_type,
error)) {
return false;
}
}
absl::string_view id = rtcp_fb_fields[1];
std::string param = "";
for (auto iter = rtcp_fb_fields.begin() + 2; iter != rtcp_fb_fields.end();
++iter) {
param.append(iter->data(), iter->length());
}
const cricket::FeedbackParam feedback_param(id, param);
if (media_type == cricket::MEDIA_TYPE_AUDIO) {
UpdateCodec<AudioContentDescription, cricket::AudioCodec>(
media_desc, payload_type, feedback_param);
} else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
UpdateCodec<VideoContentDescription, cricket::VideoCodec>(
media_desc, payload_type, feedback_param);
}
return true;
}
} // namespace webrtc
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