776 lines
25 KiB
Rust

mod macos_workaround;
use std::sync::{Arc, Mutex, Weak};
use rand::prelude::*;
use clap::Parser;
use async_std::prelude::*;
use async_std::task;
use futures::channel::mpsc;
use futures::sink::{Sink, SinkExt};
use futures::stream::StreamExt;
use async_tungstenite::tungstenite;
use tungstenite::Error as WsError;
use tungstenite::Message as WsMessage;
use gst::glib;
use gst::prelude::*;
use gst_rtp::prelude::*;
use serde_derive::{Deserialize, Serialize};
use anyhow::{anyhow, bail, Context};
const STUN_SERVER: &str = "stun://stun.l.google.com:19302";
const TURN_SERVER: &str = "turn://foo:bar@webrtc.nirbheek.in:3478";
const TWCC_URI: &str = "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01";
// upgrade weak reference or return
#[macro_export]
macro_rules! upgrade_weak {
($x:ident, $r:expr) => {{
match $x.upgrade() {
Some(o) => o,
None => return $r,
}
}};
($x:ident) => {
upgrade_weak!($x, ())
};
}
#[derive(Debug, clap::Parser)]
struct Args {
#[clap(short, long, default_value = "wss://webrtc.nirbheek.in:8443")]
server: String,
#[clap(short, long)]
peer_id: Option<u32>,
}
// JSON messages we communicate with
#[derive(Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
enum JsonMsg {
Ice {
candidate: String,
#[serde(rename = "sdpMLineIndex")]
sdp_mline_index: u32,
},
Sdp {
#[serde(rename = "type")]
type_: String,
sdp: String,
},
}
// Strong reference to our application state
#[derive(Debug, Clone)]
struct App(Arc<AppInner>);
// Weak reference to our application state
#[derive(Debug, Clone)]
struct AppWeak(Weak<AppInner>);
// Actual application state
#[derive(Debug)]
struct AppInner {
args: Args,
pipeline: gst::Pipeline,
webrtcbin: gst::Element,
send_msg_tx: Mutex<mpsc::UnboundedSender<WsMessage>>,
}
// To be able to access the App's fields directly
impl std::ops::Deref for App {
type Target = AppInner;
fn deref(&self) -> &AppInner {
&self.0
}
}
impl AppWeak {
// Try upgrading a weak reference to a strong one
fn upgrade(&self) -> Option<App> {
self.0.upgrade().map(App)
}
}
impl App {
// Downgrade the strong reference to a weak reference
fn downgrade(&self) -> AppWeak {
AppWeak(Arc::downgrade(&self.0))
}
fn new(
args: Args,
) -> Result<
(
Self,
impl Stream<Item = gst::Message>,
impl Stream<Item = WsMessage>,
),
anyhow::Error,
> {
// Create the GStreamer pipeline
let pipeline = gst::parse_launch(
"videotestsrc pattern=ball is-live=true ! vp8enc deadline=1 keyframe-max-dist=2000 ! rtpvp8pay name=vpay pt=96 picture-id-mode=15-bit ! webrtcbin. \
audiotestsrc is-live=true ! opusenc perfect-timestamp=true ! rtpopuspay name=apay pt=97 ! application/x-rtp,encoding-name=OPUS ! webrtcbin. \
webrtcbin name=webrtcbin"
)?;
// Downcast from gst::Element to gst::Pipeline
let pipeline = pipeline
.downcast::<gst::Pipeline>()
.expect("not a pipeline");
// Get access to the webrtcbin by name
let webrtcbin = pipeline.by_name("webrtcbin").expect("can't find webrtcbin");
// Set some properties on webrtcbin
webrtcbin.set_property_from_str("stun-server", STUN_SERVER);
webrtcbin.set_property_from_str("turn-server", TURN_SERVER);
webrtcbin.set_property_from_str("bundle-policy", "max-bundle");
// Create a stream for handling the GStreamer message asynchronously
let bus = pipeline.bus().unwrap();
let send_gst_msg_rx = bus.stream();
// Channel for outgoing WebSocket messages from other threads
let (send_ws_msg_tx, send_ws_msg_rx) = mpsc::unbounded::<WsMessage>();
let app = App(Arc::new(AppInner {
args,
pipeline,
webrtcbin,
send_msg_tx: Mutex::new(send_ws_msg_tx),
}));
// Connect to on-negotiation-needed to handle sending an Offer
if app.args.peer_id.is_some() {
let vpay = app.pipeline.by_name("vpay").unwrap();
let apay = app.pipeline.by_name("apay").unwrap();
for pay in [vpay, apay] {
let twcc = gst_rtp::RTPHeaderExtension::create_from_uri(TWCC_URI).unwrap();
twcc.set_id(1);
pay.emit_by_name::<()>("add-extension", &[&twcc]);
}
let app_clone = app.downgrade();
app.webrtcbin.connect_closure(
"on-negotiation-needed",
false,
glib::closure!(move |_webrtcbin: &gst::Element| {
let app = upgrade_weak!(app_clone);
if let Err(err) = app.on_negotiation_needed() {
gst::element_error!(
app.pipeline,
gst::LibraryError::Failed,
("Failed to negotiate: {:?}", err)
);
}
}),
);
}
// Whenever there is a new ICE candidate, send it to the peer
let app_clone = app.downgrade();
app.webrtcbin.connect_closure(
"on-ice-candidate",
false,
glib::closure!(
move |_webrtcbin: &gst::Element, mlineindex: u32, candidate: &str| {
let app = upgrade_weak!(app_clone);
if let Err(err) = app.on_ice_candidate(mlineindex, candidate) {
gst::element_error!(
app.pipeline,
gst::LibraryError::Failed,
("Failed to send ICE candidate: {:?}", err)
);
}
}
),
);
// Whenever there is a new stream incoming from the peer, handle it
let app_clone = app.downgrade();
app.webrtcbin.connect_pad_added(move |_webrtc, pad| {
let app = upgrade_weak!(app_clone);
if let Err(err) = app.on_incoming_stream(pad) {
gst::element_error!(
app.pipeline,
gst::LibraryError::Failed,
("Failed to handle incoming stream: {:?}", err)
);
}
});
// Asynchronously set the pipeline to Playing if we're creating the offer,
// otherwise do that after the offer was received.
if app.args.peer_id.is_some() {
app.pipeline.call_async(|pipeline| {
// If this fails, post an error on the bus so we exit
if pipeline.set_state(gst::State::Playing).is_err() {
gst::element_error!(
pipeline,
gst::LibraryError::Failed,
("Failed to set pipeline to Playing")
);
}
});
}
Ok((app, send_gst_msg_rx, send_ws_msg_rx))
}
// Handle WebSocket messages, both our own as well as WebSocket protocol messages
fn handle_websocket_message(&self, msg: &str) -> Result<(), anyhow::Error> {
if msg.starts_with("ERROR") {
bail!("Got error message: {}", msg);
}
let json_msg: JsonMsg = serde_json::from_str(msg)?;
match json_msg {
JsonMsg::Sdp { type_, sdp } => self.handle_sdp(&type_, &sdp),
JsonMsg::Ice {
sdp_mline_index,
candidate,
} => self.handle_ice(sdp_mline_index, &candidate),
}
}
// Handle GStreamer messages coming from the pipeline
fn handle_pipeline_message(&self, message: &gst::Message) -> Result<(), anyhow::Error> {
use gst::message::MessageView;
match message.view() {
MessageView::Error(err) => bail!(
"Error from element {}: {} ({})",
err.src()
.map(|s| String::from(s.path_string()))
.unwrap_or_else(|| String::from("None")),
err.error(),
err.debug().unwrap_or_else(|| String::from("None")),
),
MessageView::Warning(warning) => {
println!("Warning: \"{}\"", warning.debug().unwrap());
}
MessageView::Latency(_) => {
let _ = self.pipeline.recalculate_latency();
}
_ => (),
}
Ok(())
}
// Whenever webrtcbin tells us that (re-)negotiation is needed, simply ask
// for a new offer SDP from webrtcbin without any customization and then
// asynchronously send it to the peer via the WebSocket connection
fn on_negotiation_needed(&self) -> Result<(), anyhow::Error> {
println!("starting negotiation");
let app_clone = self.downgrade();
let promise = gst::Promise::with_change_func(move |reply| {
let app = upgrade_weak!(app_clone);
if let Err(err) = app.on_offer_created(reply) {
gst::element_error!(
app.pipeline,
gst::LibraryError::Failed,
("Failed to send SDP offer: {:?}", err)
);
}
});
self.webrtcbin
.emit_by_name::<()>("create-offer", &[&None::<gst::Structure>, &promise]);
Ok(())
}
// Once webrtcbin has create the offer SDP for us, handle it by sending it to the peer via the
// WebSocket connection
fn on_offer_created(
&self,
reply: Result<Option<&gst::StructureRef>, gst::PromiseError>,
) -> Result<(), anyhow::Error> {
let reply = match reply {
Ok(Some(reply)) => reply,
Ok(None) => {
bail!("Offer creation future got no response");
}
Err(err) => {
bail!("Offer creation future got error response: {:?}", err);
}
};
let offer = reply
.value("offer")
.unwrap()
.get::<gst_webrtc::WebRTCSessionDescription>()
.expect("Invalid argument");
self.webrtcbin
.emit_by_name::<()>("set-local-description", &[&offer, &None::<gst::Promise>]);
println!(
"sending SDP offer to peer: {}",
offer.sdp().as_text().unwrap()
);
let message = serde_json::to_string(&JsonMsg::Sdp {
type_: "offer".to_string(),
sdp: offer.sdp().as_text().unwrap(),
})
.unwrap();
self.send_msg_tx
.lock()
.unwrap()
.unbounded_send(WsMessage::Text(message))
.context("Failed to send SDP offer")?;
Ok(())
}
// Once webrtcbin has create the answer SDP for us, handle it by sending it to the peer via the
// WebSocket connection
fn on_answer_created(
&self,
reply: Result<Option<&gst::StructureRef>, gst::PromiseError>,
) -> Result<(), anyhow::Error> {
let reply = match reply {
Ok(Some(reply)) => reply,
Ok(None) => {
bail!("Answer creation future got no response");
}
Err(err) => {
bail!("Answer creation future got error response: {:?}", err);
}
};
let answer = reply
.value("answer")
.unwrap()
.get::<gst_webrtc::WebRTCSessionDescription>()
.expect("Invalid argument");
self.webrtcbin
.emit_by_name::<()>("set-local-description", &[&answer, &None::<gst::Promise>]);
println!(
"sending SDP answer to peer: {}",
answer.sdp().as_text().unwrap()
);
let message = serde_json::to_string(&JsonMsg::Sdp {
type_: "answer".to_string(),
sdp: answer.sdp().as_text().unwrap(),
})
.unwrap();
self.send_msg_tx
.lock()
.unwrap()
.unbounded_send(WsMessage::Text(message))
.context("Failed to send SDP answer")?;
Ok(())
}
fn configure_pipeline_on_offer(
&self,
offer: &gst_sdp::SDPMessage,
) -> Result<(), anyhow::Error> {
// Extract audio/video payload types from the SDP and configure accordingly on the
// pipeline as these have to match with the offer
let mut opus_id = None;
let mut vp8_id = None;
for media in offer.medias() {
for fmt in media.formats() {
if fmt == "webrtc-datachannel" {
continue;
}
let pt = match fmt.parse::<u8>() {
Ok(pt) => pt,
Err(_) => continue,
};
let caps = match media.caps_from_media(pt as i32) {
Some(caps) if caps.size() > 0 => caps,
_ => continue,
};
let s = caps.structure(0).unwrap();
let encoding_name = match s.get::<&str>("encoding-name") {
Ok(encoding_name) => encoding_name,
Err(_) => continue,
};
let twcc_id = media.attributes().find_map(|attr| {
let key = attr.key();
let value = attr.value();
if key != "extmap" || !value.map_or(false, |value| value.ends_with(TWCC_URI)) {
return None;
}
let value = value.unwrap();
let id = value
.strip_suffix(TWCC_URI)
.and_then(|id| id.trim().parse::<u8>().ok());
id
});
if encoding_name == "VP8" && vp8_id.is_none() {
vp8_id = Some((pt, twcc_id));
} else if encoding_name == "OPUS" && opus_id.is_none() {
opus_id = Some((pt, twcc_id));
}
}
}
if let (Some(opus_id), Some(vp8_id)) = (opus_id, vp8_id) {
let apay = self.pipeline.by_name("apay").unwrap();
let vpay = self.pipeline.by_name("vpay").unwrap();
for (pay, (pt, twcc_id)) in [(apay, opus_id), (vpay, vp8_id)] {
pay.set_property("pt", pt as u32);
if let Some(twcc_id) = twcc_id {
let twcc = gst_rtp::RTPHeaderExtension::create_from_uri(TWCC_URI).unwrap();
twcc.set_id(twcc_id as u32);
pay.emit_by_name::<()>("add-extension", &[&twcc]);
}
}
} else {
gst::element_error!(
self.pipeline,
gst::LibraryError::Failed,
("Not all streams found in the offer")
);
bail!("Not all streams found in the offer");
}
Ok(())
}
// Handle incoming SDP answers from the peer
fn handle_sdp(&self, type_: &str, sdp: &str) -> Result<(), anyhow::Error> {
if type_ == "answer" {
print!("Received answer:\n{}\n", sdp);
let ret = gst_sdp::SDPMessage::parse_buffer(sdp.as_bytes())
.map_err(|_| anyhow!("Failed to parse SDP answer"))?;
let answer =
gst_webrtc::WebRTCSessionDescription::new(gst_webrtc::WebRTCSDPType::Answer, ret);
self.webrtcbin
.emit_by_name::<()>("set-remote-description", &[&answer, &None::<gst::Promise>]);
Ok(())
} else if type_ == "offer" {
print!("Received offer:\n{}\n", sdp);
let ret = gst_sdp::SDPMessage::parse_buffer(sdp.as_bytes())
.map_err(|_| anyhow!("Failed to parse SDP offer"))?;
// And then asynchronously start our pipeline and do the next steps. The
// pipeline needs to be started before we can create an answer
let app_clone = self.downgrade();
self.pipeline.call_async(move |_pipeline| {
let app = upgrade_weak!(app_clone);
if app.configure_pipeline_on_offer(&ret).is_err() {
return;
}
// If this fails, post an error on the bus so we exit
if app.pipeline.set_state(gst::State::Playing).is_err() {
gst::element_error!(
app.pipeline,
gst::LibraryError::Failed,
("Failed to set pipeline to Playing")
);
return;
}
let offer = gst_webrtc::WebRTCSessionDescription::new(
gst_webrtc::WebRTCSDPType::Offer,
ret,
);
app.0
.webrtcbin
.emit_by_name::<()>("set-remote-description", &[&offer, &None::<gst::Promise>]);
let app_clone = app.downgrade();
let promise = gst::Promise::with_change_func(move |reply| {
let app = upgrade_weak!(app_clone);
if let Err(err) = app.on_answer_created(reply) {
gst::element_error!(
app.pipeline,
gst::LibraryError::Failed,
("Failed to send SDP answer: {:?}", err)
);
}
});
app.0
.webrtcbin
.emit_by_name::<()>("create-answer", &[&None::<gst::Structure>, &promise]);
});
Ok(())
} else {
bail!("Sdp type is not \"answer\" but \"{}\"", type_)
}
}
// Handle incoming ICE candidates from the peer by passing them to webrtcbin
fn handle_ice(&self, sdp_mline_index: u32, candidate: &str) -> Result<(), anyhow::Error> {
self.webrtcbin
.emit_by_name::<()>("add-ice-candidate", &[&sdp_mline_index, &candidate]);
Ok(())
}
// Asynchronously send ICE candidates to the peer via the WebSocket connection as a JSON
// message
fn on_ice_candidate(&self, mlineindex: u32, candidate: &str) -> Result<(), anyhow::Error> {
let message = serde_json::to_string(&JsonMsg::Ice {
candidate: candidate.to_string(),
sdp_mline_index: mlineindex,
})
.unwrap();
self.send_msg_tx
.lock()
.unwrap()
.unbounded_send(WsMessage::Text(message))
.context("Failed to send ICE candidate")?;
Ok(())
}
// Whenever there's a new incoming, encoded stream from the peer create a new decodebin
fn on_incoming_stream(&self, pad: &gst::Pad) -> Result<(), anyhow::Error> {
// Early return for the source pads we're adding ourselves
if pad.direction() != gst::PadDirection::Src {
return Ok(());
}
let decodebin = gst::ElementFactory::make("decodebin").build().unwrap();
let app_clone = self.downgrade();
decodebin.connect_pad_added(move |_decodebin, pad| {
let app = upgrade_weak!(app_clone);
if let Err(err) = app.on_incoming_decodebin_stream(pad) {
gst::element_error!(
app.pipeline,
gst::LibraryError::Failed,
("Failed to handle decoded stream: {:?}", err)
);
}
});
self.pipeline.add(&decodebin).unwrap();
decodebin.sync_state_with_parent().unwrap();
let sinkpad = decodebin.static_pad("sink").unwrap();
pad.link(&sinkpad).unwrap();
Ok(())
}
// Handle a newly decoded decodebin stream and depending on its type, create the relevant
// elements or simply ignore it
fn on_incoming_decodebin_stream(&self, pad: &gst::Pad) -> Result<(), anyhow::Error> {
let caps = pad.current_caps().unwrap();
let name = caps.structure(0).unwrap().name();
let sink = if name.starts_with("video/") {
gst::parse_bin_from_description(
"queue ! videoconvert ! videoscale ! autovideosink",
true,
)?
} else if name.starts_with("audio/") {
gst::parse_bin_from_description(
"queue ! audioconvert ! audioresample ! autoaudiosink",
true,
)?
} else {
println!("Unknown pad {:?}, ignoring", pad);
return Ok(());
};
self.pipeline.add(&sink).unwrap();
sink.sync_state_with_parent()
.with_context(|| format!("can't start sink for stream {:?}", caps))?;
let sinkpad = sink.static_pad("sink").unwrap();
pad.link(&sinkpad)
.with_context(|| format!("can't link sink for stream {:?}", caps))?;
Ok(())
}
}
// Make sure to shut down the pipeline when it goes out of scope
// to release any system resources
impl Drop for AppInner {
fn drop(&mut self) {
let _ = self.pipeline.set_state(gst::State::Null);
}
}
async fn run(
args: Args,
ws: impl Sink<WsMessage, Error = WsError> + Stream<Item = Result<WsMessage, WsError>>,
) -> Result<(), anyhow::Error> {
// Split the websocket into the Sink and Stream
let (mut ws_sink, ws_stream) = ws.split();
// Fuse the Stream, required for the select macro
let mut ws_stream = ws_stream.fuse();
// Create our application state
let (app, send_gst_msg_rx, send_ws_msg_rx) = App::new(args)?;
let mut send_gst_msg_rx = send_gst_msg_rx.fuse();
let mut send_ws_msg_rx = send_ws_msg_rx.fuse();
// And now let's start our message loop
loop {
let ws_msg = futures::select! {
// Handle the WebSocket messages here
ws_msg = ws_stream.select_next_some() => {
match ws_msg? {
WsMessage::Close(_) => {
println!("peer disconnected");
break
},
WsMessage::Ping(data) => Some(WsMessage::Pong(data)),
WsMessage::Pong(_) => None,
WsMessage::Binary(_) => None,
WsMessage::Text(text) => {
app.handle_websocket_message(&text)?;
None
},
WsMessage::Frame(_) => unreachable!(),
}
},
// Pass the GStreamer messages to the application control logic
gst_msg = send_gst_msg_rx.select_next_some() => {
app.handle_pipeline_message(&gst_msg)?;
None
},
// Handle WebSocket messages we created asynchronously
// to send them out now
ws_msg = send_ws_msg_rx.select_next_some() => Some(ws_msg),
// Once we're done, break the loop and return
complete => break,
};
// If there's a message to send out, do so now
if let Some(ws_msg) = ws_msg {
ws_sink.send(ws_msg).await?;
}
}
Ok(())
}
// Check if all GStreamer plugins we require are available
fn check_plugins() -> Result<(), anyhow::Error> {
let needed = [
"videotestsrc",
"audiotestsrc",
"videoconvertscale",
"audioconvert",
"autodetect",
"opus",
"vpx",
"webrtc",
"nice",
"dtls",
"srtp",
"rtpmanager",
"rtp",
"playback",
"audioresample",
];
let registry = gst::Registry::get();
let missing = needed
.iter()
.filter(|n| registry.find_plugin(n).is_none())
.cloned()
.collect::<Vec<_>>();
if !missing.is_empty() {
bail!("Missing plugins: {:?}", missing);
} else {
Ok(())
}
}
async fn async_main() -> Result<(), anyhow::Error> {
// Initialize GStreamer first
gst::init()?;
check_plugins()?;
let args = Args::parse();
// Connect to the given server
let (mut ws, _) = async_tungstenite::async_std::connect_async(&args.server).await?;
println!("connected");
// Say HELLO to the server and see if it replies with HELLO
let our_id = rand::thread_rng().gen_range(10..10_000);
println!("Registering id {} with server", our_id);
ws.send(WsMessage::Text(format!("HELLO {}", our_id)))
.await?;
let msg = ws
.next()
.await
.ok_or_else(|| anyhow!("didn't receive anything"))??;
if msg != WsMessage::Text("HELLO".into()) {
bail!("server didn't say HELLO");
}
if let Some(peer_id) = args.peer_id {
// Join the given session
ws.send(WsMessage::Text(format!("SESSION {}", peer_id)))
.await?;
let msg = ws
.next()
.await
.ok_or_else(|| anyhow!("didn't receive anything"))??;
if msg != WsMessage::Text("SESSION_OK".into()) {
bail!("server error: {:?}", msg);
}
}
// All good, let's run our message loop
run(args, ws).await
}
fn main() -> Result<(), anyhow::Error> {
macos_workaround::run(|| task::block_on(async_main()))
}