Jingle Calls and Jitsi

import { xml } from "@xmpp/client";

const NS = {
  jingle: "urn:xmpp:jingle:1",
  rtp: "urn:xmpp:jingle:apps:rtp:1",
  hdrext: "urn:xmpp:jingle:apps:rtp:rtp-hdrext:0",
  rtcpfb: "urn:xmpp:jingle:apps:rtp:rtcp-fb:0",
  ice: "urn:xmpp:jingle:transports:ice-udp:1",
  dtls: "urn:xmpp:jingle:apps:dtls:0",
  group: "urn:xmpp:jingle:apps:grouping:0",
};
const SENDERS = { sendrecv: "both", sendonly: "initiator", recvonly: "responder", inactive: "none" };

function parseSections(sdp) {
  const lines = sdp.split(/\r?\n/).filter(Boolean);
  const session = { attrs: [] };
  const media = [];
  let cur = session;
  for (const line of lines) {
    if (line.startsWith("m=")) { cur = { m: line.slice(2).split(" "), attrs: [] }; media.push(cur); }
    else if (line.startsWith("a=")) cur.attrs.push(line.slice(2));
  }
  return { session, media };
}
const attr = (sec, name) => sec.attrs.find((a) => a === name || a.startsWith(`${name}:`))?.slice(name.length + 1);
const attrs = (sec, name) => sec.attrs.filter((a) => a.startsWith(`${name}:`)).map((a) => a.slice(name.length + 1));

function candidate(line) {
  const [foundation, component, protocol, priority, ip, port, , type, ...rest] = line.split(" ");
  const out = { component, foundation, generation: "0", id: `c-${foundation}`, ip, network: "0", port, priority, protocol: protocol.toLowerCase(), type };
  for (let i = 0; i < rest.length; i += 2) {
    if (rest[i] === "raddr") out["rel-addr"] = rest[i + 1];
    if (rest[i] === "rport") out["rel-port"] = rest[i + 1];
    if (rest[i] === "generation") out.generation = rest[i + 1];
  }
  return out;
}

export function sdpToJingle(sdp, { sid, initiator, action = "session-initiate" }) {
  const { session, media } = parseSections(sdp);
  const jingle = xml("jingle", { xmlns: NS.jingle, action, sid, initiator });
  const bundle = attr(session, "group")?.split(" ");
  if (bundle?.[0] === "BUNDLE") {
    jingle.append(xml("group", { xmlns: NS.group, semantics: "BUNDLE" }, ...bundle.slice(1).map((name) => xml("content", { name }))));
  }
  for (const m of media) {
    const [kind, , , ...pts] = m.m;
    const name = attr(m, "mid");
    const direction = ["sendrecv", "sendonly", "recvonly", "inactive"].find((d) => m.attrs.includes(d)) ?? "sendrecv";
    const description = xml("description", { xmlns: NS.rtp, media: kind });
    for (const pt of pts) {
      const [codec, clockrate, channels] = (attrs(m, "rtpmap").find((r) => r.startsWith(`${pt} `)) ?? "").slice(pt.length + 1).split("/");
      const payload = xml("payload-type", { id: pt, ...(codec && { name: codec, clockrate }), ...(channels && { channels }) });
      const fmtp = attrs(m, "fmtp").find((f) => f.startsWith(`${pt} `));
      for (const kv of (fmtp ?? "").slice(pt.length + 1).split(";").filter(Boolean)) {
        const [k, v = ""] = kv.trim().split("=");
        payload.append(xml("parameter", { name: k, value: v }));
      }
      for (const fb of attrs(m, "rtcp-fb").filter((f) => f.startsWith(`${pt} `))) {
        const [, type, subtype] = fb.split(" ");
        payload.append(xml("rtcp-fb", { xmlns: NS.rtcpfb, type, ...(subtype && { subtype }) }));
      }
      description.append(payload);
    }
    if (m.attrs.includes("rtcp-mux")) description.append(xml("rtcp-mux"));
    for (const e of attrs(m, "extmap")) {
      const [idPart, uri] = e.split(" ");
      description.append(xml("rtp-hdrext", { xmlns: NS.hdrext, id: idPart.split("/")[0], uri, senders: "both" }));
    }
    const [hash, fingerprint] = (attr(m, "fingerprint") ?? "").split(" ");
    const transport = xml("transport", { xmlns: NS.ice, ufrag: attr(m, "ice-ufrag"), pwd: attr(m, "ice-pwd") });
    if (fingerprint) transport.append(xml("fingerprint", { xmlns: NS.dtls, hash, setup: attr(m, "setup") }, fingerprint));
    for (const c of attrs(m, "candidate").map(candidate)) {
      if (c.protocol === "udp") transport.append(xml("candidate", c));   // the ice-udp transport carries UDP candidates only
    }
    jingle.append(xml("content", { creator: "initiator", name, senders: SENDERS[direction] }, description, transport));
  }
  return jingle;
}

<jingle xmlns="urn:xmpp:jingle:1" action="session-initiate" sid="a73sjjvkla37jfea" initiator="alice@chat.example.test/web">
  <group xmlns="urn:xmpp:jingle:apps:grouping:0" semantics="BUNDLE"><content name="0"/></group>
  <content creator="initiator" name="0" senders="both">
    <description xmlns="urn:xmpp:jingle:apps:rtp:1" media="audio">
      <payload-type id="111" name="opus" clockrate="48000" channels="2">
        <parameter name="minptime" value="10"/>
        <parameter name="useinbandfec" value="1"/>
        <rtcp-fb xmlns="urn:xmpp:jingle:apps:rtp:rtcp-fb:0" type="transport-cc"/>
      </payload-type>
      <payload-type id="9" name="G722" clockrate="8000"/>
      <payload-type id="0" name="PCMU" clockrate="8000"/>
      <rtcp-mux/>
      <rtp-hdrext xmlns="urn:xmpp:jingle:apps:rtp:rtp-hdrext:0" id="1" uri="urn:ietf:params:rtp-hdrext:ssrc-audio-level" senders="both"/>
    </description>
    <transport xmlns="urn:xmpp:jingle:transports:ice-udp:1" ufrag="LSox" pwd="change-me-ice-pwd">
      <fingerprint xmlns="urn:xmpp:jingle:apps:dtls:0" hash="sha-256" setup="actpass">5C:9B:DB:80:DD:B2:E9:4C:...:55:30:EF</fingerprint>
      <candidate component="1" foundation="409278917" generation="0" id="c-409278917" ip="192.0.2.10" network="0" port="62131" priority="2122194687" protocol="udp" type="host"/>
    </transport>
  </content>
</jingle>

<message to="bob@chat.example.test" type="chat">
  <propose xmlns="urn:xmpp:jingle-message:0" id="ca3cf894-5325-482f-a412-a6e9f832298d">
    <description xmlns="urn:xmpp:jingle:apps:rtp:1" media="audio"/>
    <description xmlns="urn:xmpp:jingle:apps:rtp:1" media="video"/>
  </propose>
  <store xmlns="urn:xmpp:hints"/>
</message>

import { xml } from "@xmpp/client";

// XEP-0215: ask the server for STUN and TURN services and turn them into RTCPeerConnection iceServers.
export async function getIceServers(xmpp, domain) {
  const res = await xmpp.iqCaller.request(
    xml("iq", { type: "get", to: domain }, xml("services", { xmlns: "urn:xmpp:extdisco:2" })), 10000);
  const iceServers = [];
  for (const s of res.getChild("services", "urn:xmpp:extdisco:2").getChildren("service")) {
    const { type, host, port, transport = "udp", username, password } = s.attrs;
    if (type !== "stun" && type !== "turn") continue;
    const scheme = transport === "tls" ? `${type}s` : type;
    const url = `${scheme}:${host}${port ? `:${port}` : ""}${transport === "tcp" ? "?transport=tcp" : ""}`;
    iceServers.push(type === "turn" ? { urls: url, username, credential: password } : { urls: url });
  }
  return iceServers;
}