1 files changed, 54 insertions, 12 deletions
diff --git a/src/calls.js b/src/calls.js
index 66d6f16..6f18aec 100644
--- a/src/calls.js
+++ b/src/calls.js
@@ -71,6 +71,8 @@ export const candidateJson = (c) => JSON.stringify({ candidate: c.candidate, sdp
 //   trickle()             false for a signer that's slow or asks each time (a
 //                         bunker, Amber): the candidates go inside the offer or
 //                         answer instead of one signed message each
+//   warm(pk)              a call with them may be coming: look up what sending to
+//                         them takes (their relays, TURN) ahead of it
 //   RTCPeerConnection     (tests may pass their own)
 export function createCalls(env) {
   const PC = env.RTCPeerConnection || globalThis.RTCPeerConnection;
@@ -103,8 +105,10 @@ export function createCalls(env) {
     endTimer = setTimeout(() => { if (call === c) { call = null; changed(); } }, ENDED_MS);
   }
 
+  // (iceCandidatePoolSize: the routes — TURN's included, which take a round
+  // trip to allocate — are gathered from the start, not from the answer on)
   async function connection(c) {
-    const pc = new PC({ iceServers: await env.iceServers(), bundlePolicy: 'max-bundle' });
+    const pc = new PC({ iceServers: await env.iceServers(), bundlePolicy: 'max-bundle', iceCandidatePoolSize: 2 });
     c.pc = pc;
     c.remote = new MediaStream();
     pc.ontrack = (e) => { for (const t of (e.streams[0] || { getTracks: () => [e.track] }).getTracks()) if (!c.remote.getTracks().includes(t)) c.remote.addTrack(t); changed(); };
@@ -121,17 +125,47 @@ export function createCalls(env) {
       if (s === 'connected' && c.state !== 'connected') { c.state = 'connected'; c.connectedAt = Date.now(); clearTimeout(ringTimer); changed(); }
       else if (s === 'failed') end('failed', c);
     };
-    for (const t of c.local.getTracks()) pc.addTrack(t, c.local);
+    if (c.local) for (const t of c.local.getTracks()) pc.addTrack(t, c.local);
     return pc;
   }
-  // without trickle: the description once its candidates are gathered (a few seconds at most)
+  // While a call rings: its connection made and the offer set, the routes
+  // gathering — everything but the microphone and camera, which wait for
+  // Answer. Answering then only adds them and replies (it used to do all of
+  // this after the tap, seconds of "Connecting…").
+  async function prepare(c) {
+    const pc = await connection(c);
+    if (call !== c || c.state === 'ended') { try { pc.close(); } catch {} return null; }
+    await pc.setRemoteDescription({ type: 'offer', sdp: c.offer });
+    c.remoteSet = true;
+    await addCandidates(c);
+    return pc;
+  }
+  // our tracks into the transceivers the offer made
+  function attachLocal(c) {
+    const trs = c.pc.getTransceivers();
+    for (const track of c.local.getTracks()) {
+      const tr = trs.find((x) => !x.sender.track && x.receiver.track && x.receiver.track.kind === track.kind && !x.stopped);
+      if (tr) {
+        tr.sender.replaceTrack(track);
+        tr.direction = 'sendrecv';
+        try { tr.sender.setStreams && tr.sender.setStreams(c.local); } catch {}
+      } else c.pc.addTrack(track, c.local);
+    }
+  }
+  // Without trickle: the description once it holds routes enough — one
+  // through the router (srflx) and one through TURN (relay) — or after a
+  // second and a half. Waiting for gathering to finish took up to 4 s (TURN
+  // over TCP and TLS is slow to give up), all of it after the tap.
   async function described(c) {
     const pc = c.pc;
-    if (!c.trickle && pc.iceGatheringState !== 'complete') {
+    const enough = () => pc.iceGatheringState === 'complete'
+      || (/ typ srflx/.test(pc.localDescription.sdp) && / typ relay/.test(pc.localDescription.sdp));
+    if (!c.trickle && !enough()) {
       await new Promise((resolve) => {
-        const done = () => { if (pc.iceGatheringState === 'complete') resolve(); };
-        pc.addEventListener('icegatheringstatechange', done);
-        setTimeout(resolve, 4000);
+        const check = () => { if (enough()) resolve(); };
+        pc.addEventListener('icegatheringstatechange', check);
+        pc.addEventListener('icecandidate', check);
+        setTimeout(resolve, 1500);
       });
     }
     return pc.localDescription.sdp;
@@ -169,12 +203,18 @@ export function createCalls(env) {
     c.state = 'connecting';
     changed();
     try {
-      c.local = await env.media(c.type, c.facing);
+      const [local, ready] = await Promise.all([env.media(c.type, c.facing), (c.prep || Promise.resolve(null)).catch(() => null)]);
+      c.local = local;
       if (call !== c) { stopMedia(c); return; }
-      const pc = await connection(c);
-      await pc.setRemoteDescription({ type: 'offer', sdp: c.offer });
-      c.remoteSet = true;
-      await addCandidates(c);
+      let pc = ready;
+      if (pc && pc.signalingState === 'have-remote-offer') attachLocal(c);
+      else { // nothing made while it rang (or it failed): all of it now
+        try { pc && pc.close(); } catch {}
+        pc = await connection(c);
+        await pc.setRemoteDescription({ type: 'offer', sdp: c.offer });
+        c.remoteSet = true;
+        await addCandidates(c);
+      }
       await pc.setLocalDescription(await pc.createAnswer());
       const signed = await env.sign(callEvent(CALL.ANSWER, c.peer, c.id, await described(c)));
       await env.send(c.peer, signed);
@@ -261,6 +301,8 @@ export function createCalls(env) {
         const n = call = { id, peer: from, type, dir: 'in', state: 'incoming', offer: ev.content, ice: [], at: Date.now(), offerAt: ev.created_at * 1000, muted: false, camOff: false, facing: 'user' };
         ringTimer = setTimeout(() => { if (call === n && n.state === 'incoming') end('missed', n); }, Math.max(5000, RING_MS - (Date.now() - ev.created_at * 1000)));
         changed();
+        try { if (env.warm) env.warm(from); } catch {}
+        n.prep = prepare(n).catch(() => null);
         return;
       }
       case CALL.ANSWER: {