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Refactored SDP parsing and generation to handle media

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This commit is contained in:
Paul-Louis Ageneau
2020-03-22 23:04:05 +01:00
parent d4c5ef8155
commit 9204787677
4 changed files with 196 additions and 71 deletions
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25
include/rtc/description.hpp
View File

@ -42,7 +42,7 @@ public:
string typeString() const;
Role role() const;
string roleString() const;
string mid() const;
string dataMid() const;
std::optional<string> fingerprint() const;
std::optional<uint16_t> sctpPort() const;
std::optional<size_t> maxMessageSize() const;
@ -65,11 +65,28 @@ private:
Type mType;
Role mRole;
string mSessionId;
string mMid;
string mIceUfrag, mIcePwd;
std::optional<string> mFingerprint;
std::optional<uint16_t> mSctpPort;
std::optional<size_t> mMaxMessageSize;
// Data
struct Data {
string mid;
std::optional<uint16_t> sctpPort;
std::optional<size_t> maxMessageSize;
};
Data mData;
// Media (non-data)
struct Media {
string description;
string mid;
std::vector<string> attributes;
string type() const;
};
std::map<string, Media> mMedia; // by mid
// Candidates
std::vector<Candidate> mCandidates;
bool mTrickle;

2
include/rtc/peerconnection.hpp
View File

@ -75,6 +75,7 @@ public:
std::optional<string> localAddress() const;
std::optional<string> remoteAddress() const;
void setLocalDescription(Description description);
void setRemoteDescription(Description description);
void addRemoteCandidate(Candidate candidate);
@ -104,6 +105,7 @@ private:
void endLocalCandidates();
bool checkFingerprint(const std::string &fingerprint) const;
void forwardMessage(message_ptr message);
void forwardMedia(message_ptr message);
void forwardBufferedAmount(uint16_t stream, size_t amount);
std::shared_ptr<DataChannel> emplaceDataChannel(Description::Role role, const string &label,

165
src/description.cpp
View File

@ -29,7 +29,7 @@ using std::string;
namespace {
inline bool hasprefix(const string &str, const string &prefix) {
inline bool match_prefix(const string &str, const string &prefix) {
return str.size() >= prefix.size() &&
std::mismatch(prefix.begin(), prefix.end(), str.begin()).first == prefix.end();
}
@ -50,7 +50,8 @@ Description::Description(const string &sdp, const string &typeString)
Description::Description(const string &sdp, Type type) : Description(sdp, type, Role::ActPass) {}
Description::Description(const string &sdp, Type type, Role role)
: mType(Type::Unspec), mRole(role), mMid("0"), mIceUfrag(""), mIcePwd(""), mTrickle(true) {
: mType(Type::Unspec), mRole(role), mIceUfrag(""), mIcePwd(""), mTrickle(true) {
mData.mid = "data";
hintType(type);
auto seed = std::chrono::system_clock::now().time_since_epoch().count();
@ -59,37 +60,78 @@ Description::Description(const string &sdp, Type type, Role role)
mSessionId = std::to_string(uniform(generator));
std::istringstream ss(sdp);
std::optional<Media> currentMedia;
string line;
while (std::getline(ss, line)) {
bool finished;
do {
bool finished = !std::getline(ss, line) && line.empty();
trim_end(line);
if (hasprefix(line, "a=setup:")) {
const string setup = line.substr(line.find(':') + 1);
if (setup == "active")
mRole = Role::Active;
else if (setup == "passive")
mRole = Role::Passive;
else
mRole = Role::ActPass;
} else if (hasprefix(line, "a=mid:")) {
mMid = line.substr(line.find(':') + 1);
} else if (hasprefix(line, "a=fingerprint:sha-256")) {
mFingerprint = line.substr(line.find(' ') + 1);
std::transform(mFingerprint->begin(), mFingerprint->end(), mFingerprint->begin(),
[](char c) { return std::toupper(c); });
} else if (hasprefix(line, "a=ice-ufrag")) {
mIceUfrag = line.substr(line.find(':') + 1);
} else if (hasprefix(line, "a=ice-pwd")) {
mIcePwd = line.substr(line.find(':') + 1);
} else if (hasprefix(line, "a=sctp-port")) {
mSctpPort = uint16_t(std::stoul(line.substr(line.find(':') + 1)));
} else if (hasprefix(line, "a=max-message-size")) {
mMaxMessageSize = size_t(std::stoul(line.substr(line.find(':') + 1)));
} else if (hasprefix(line, "a=candidate")) {
addCandidate(Candidate(line.substr(2), mMid));
} else if (hasprefix(line, "a=end-of-candidates")) {
mTrickle = false;
// Media description line (aka m-line)
if (finished || match_prefix(line, "m=")) {
if (currentMedia) {
if (!currentMedia->mid.empty()) {
if (currentMedia->type() == "application")
mData.mid = currentMedia->mid;
else
mMedia.emplace(currentMedia->mid, std::move(*currentMedia));
} else {
PLOG_WARNING << "SDP \"m=\" line has no mid, ignoring";
}
}
if (!finished)
currentMedia.emplace(Media{line.substr(2)});
// Attribute line
} else if (match_prefix(line, "a=")) {
string attr = line.substr(2);
string key, value;
if (size_t separator = attr.find(':'); separator != string::npos) {
key = attr.substr(0, separator);
value = attr.substr(separator + 1);
} else {
key = attr;
}
if (key == "mid") {
if (currentMedia)
currentMedia->mid = value;
} else if (key == "setup") {
if (value == "active")
mRole = Role::Active;
else if (value == "passive")
mRole = Role::Passive;
else
mRole = Role::ActPass;
} else if (key == "fingerprint") {
if (match_prefix(value, "sha-256 ")) {
mFingerprint = value.substr(8);
std::transform(mFingerprint->begin(), mFingerprint->end(),
mFingerprint->begin(), [](char c) { return std::toupper(c); });
} else {
PLOG_WARNING << "Unknown SDP fingerprint type: " << value;
}
} else if (key == "ice-ufrag") {
mIceUfrag = value;
} else if (key == "ice-pwd") {
mIcePwd = value;
} else if (key == "sctp-port") {
mData.sctpPort = uint16_t(std::stoul(value));
} else if (key == "max-message-size") {
mData.maxMessageSize = size_t(std::stoul(value));
} else if (key == "candidate") {
addCandidate(Candidate(attr, currentMedia ? currentMedia->mid : mData.mid));
} else if (key == "end-of-candidates") {
mTrickle = false;
} else if (currentMedia) {
currentMedia->attributes.emplace_back(line.substr(2));
}
}
}
} while (!finished);
}
Description::Type Description::type() const { return mType; }
@ -100,13 +142,13 @@ Description::Role Description::role() const { return mRole; }
string Description::roleString() const { return roleToString(mRole); }
string Description::mid() const { return mMid; }
string Description::dataMid() const { return mData.mid; }
std::optional<string> Description::fingerprint() const { return mFingerprint; }
std::optional<uint16_t> Description::sctpPort() const { return mSctpPort; }
std::optional<uint16_t> Description::sctpPort() const { return mData.sctpPort; }
std::optional<size_t> Description::maxMessageSize() const { return mMaxMessageSize; }
std::optional<size_t> Description::maxMessageSize() const { return mData.maxMessageSize; }
bool Description::trickleEnabled() const { return mTrickle; }
@ -122,9 +164,9 @@ void Description::setFingerprint(string fingerprint) {
mFingerprint.emplace(std::move(fingerprint));
}
void Description::setSctpPort(uint16_t port) { mSctpPort.emplace(port); }
void Description::setSctpPort(uint16_t port) { mData.sctpPort.emplace(port); }
void Description::setMaxMessageSize(size_t size) { mMaxMessageSize.emplace(size); }
void Description::setMaxMessageSize(size_t size) { mData.maxMessageSize.emplace(size); }
void Description::addCandidate(Candidate candidate) {
mCandidates.emplace_back(std::move(candidate));
@ -146,36 +188,67 @@ string Description::generateSdp(const string &eol) const {
throw std::logic_error("Fingerprint must be set to generate an SDP string");
std::ostringstream sdp;
// Header
sdp << "v=0" << eol;
sdp << "o=- " << mSessionId << " 0 IN IP4 127.0.0.1" << eol;
sdp << "s=-" << eol;
sdp << "t=0 0" << eol;
sdp << "a=group:BUNDLE 0" << eol;
// Bundle
sdp << "a=group:BUNDLE";
for (const auto &[mid, _] : mMedia)
sdp << " " << mid;
sdp << " " << mData.mid << eol;
// Non-data media
if (!mMedia.empty()) {
// Lip-sync
sdp << "a=group:LS";
for (const auto &[mid, _] : mMedia)
sdp << " " << mid;
sdp << eol;
// Descriptions and attributes
for (const auto &[_, media] : mMedia) {
sdp << "m=" << media.description << eol;
sdp << "c=IN IP4 0.0.0.0" << eol;
sdp << "a=mid:" << media.mid << eol;
for (const auto &attr : media.attributes)
sdp << "a=" << attr << eol;
}
}
// Data
sdp << "m=application 9 UDP/DTLS/SCTP webrtc-datachannel" << eol;
sdp << "c=IN IP4 0.0.0.0" << eol;
sdp << "a=ice-ufrag:" << mIceUfrag << eol;
sdp << "a=ice-pwd:" << mIcePwd << eol;
sdp << "a=mid:" << mData.mid << eol;
if (mData.sctpPort)
sdp << "a=sctp-port:" << *mData.sctpPort << eol;
if (mData.maxMessageSize)
sdp << "a=max-message-size:" << *mData.maxMessageSize << eol;
// Common
if (mTrickle)
sdp << "a=ice-options:trickle" << eol;
sdp << "a=mid:" << mMid << eol;
sdp << "a=ice-ufrag:" << mIceUfrag << eol;
sdp << "a=ice-pwd:" << mIcePwd << eol;
sdp << "a=setup:" << roleToString(mRole) << eol;
sdp << "a=dtls-id:1" << eol;
if (mFingerprint)
sdp << "a=fingerprint:sha-256 " << *mFingerprint << eol;
if (mSctpPort)
sdp << "a=sctp-port:" << *mSctpPort << eol;
if (mMaxMessageSize)
sdp << "a=max-message-size:" << *mMaxMessageSize << eol;
for (const auto &candidate : mCandidates) {
sdp << string(candidate) << eol;
}
// Candidates
for (const auto &candidate : mCandidates)
sdp << string(candidate) << eol;
if (!mTrickle)
sdp << "a=end-of-candidates" << eol;
return sdp.str();
}
string Description::Media::type() const { return description.substr(0, description.find(' ')); }
Description::Type Description::stringToType(const string &typeString) {
if (typeString == "offer")
return Type::Offer;

75
src/peerconnection.cpp
View File

@ -23,6 +23,10 @@
#include "include.hpp"
#include "sctptransport.hpp"
#if RTC_ENABLE_MEDIA
#include "dtlssrtptransport.hpp"
#endif
#include <thread>
namespace rtc {
@ -61,6 +65,21 @@ std::optional<Description> PeerConnection::remoteDescription() const {
return mRemoteDescription;
}
void PeerConnection::setLocalDescription(Description description) {
if (auto iceTransport = std::atomic_load(&mIceTransport)) {
throw std::logic_error("Local description is already set");
} else {
// RFC 5763: The endpoint that is the offerer MUST use the setup attribute value of
// setup:actpass.
// See https://tools.ietf.org/html/rfc5763#section-5
iceTransport = initIceTransport(Description::Role::ActPass);
Description localDescription = iceTransport->getLocalDescription(Description::Type::Offer);
localDescription.addMedia(description); // TODO
processLocalDescription(description);
iceTransport->gatherLocalCandidates();
}
}
void PeerConnection::setRemoteDescription(Description description) {
description.hintType(localDescription() ? Description::Type::Answer : Description::Type::Offer);
auto remoteCandidates = description.extractCandidates();
@ -252,27 +271,37 @@ shared_ptr<DtlsTransport> PeerConnection::initDtlsTransport() {
return transport;
auto lower = std::atomic_load(&mIceTransport);
auto transport = std::make_shared<DtlsTransport>(
lower, mCertificate, weak_bind(&PeerConnection::checkFingerprint, this, _1),
[this, weak_this = weak_from_this()](DtlsTransport::State state) {
auto shared_this = weak_this.lock();
if (!shared_this)
return;
switch (state) {
case DtlsTransport::State::Connected:
initSctpTransport();
break;
case DtlsTransport::State::Failed:
changeState(State::Failed);
break;
case DtlsTransport::State::Disconnected:
changeState(State::Disconnected);
break;
default:
// Ignore
break;
}
});
auto verifierCallback = weak_bind(&PeerConnection::checkFingerprint, this, _1);
auto stateChangeCallback = [this,
weak_this = weak_from_this()](DtlsTransport::State state) {
switch (state) {
case DtlsTransport::State::Connected:
initSctpTransport();
break;
case DtlsTransport::State::Failed:
changeState(State::Failed);
break;
case DtlsTransport::State::Disconnected:
changeState(State::Disconnected);
break;
default:
// Ignore
break;
}
};
shared_ptr<DtlsTransport> transport;
#if RTC_ENABLE_MEDIA
auto local = localDescription();
auto remote = remoteDescription();
if ((local && local->hasMedia()) || (remote && remote->hasMedia()))
transport = std::make_shared<DtlsSrtpTransport>(
lower, mCertificate, verifierCallback,
std::bind(&PeerConnection::forwardMedia, this, _1), stateChangeCallback);
else
#endif
transport = std::make_shared<DtlsTransport>(lower, mCertificate, verifierCallback,
stateChangeCallback);
std::atomic_store(&mDtlsTransport, transport);
if (mState == State::Closed) {
@ -413,6 +442,10 @@ void PeerConnection::forwardMessage(message_ptr message) {
channel->incoming(message);
}
void PeerConnection::forwardMedia(message_ptr message) {
// TODO
}
void PeerConnection::forwardBufferedAmount(uint16_t stream, size_t amount) {
if (auto channel = findDataChannel(stream))
channel->triggerBufferedAmount(amount);