Allow subscribes to clients

Summary: When a client publishes via relay it has to accept subscribes

Reviewed By: yuandagits

Differential Revision: D64016783

fbshipit-source-id: 18c5849c5e6abedfedee67bf10f48c2c40f1924b

Author: afrind

moxygen/MoQClient.cpp

@@ -92,11 +92,15 @@ folly::coro::Task<void> MoQClient::setupMoQSession(
   // Setup MoQSession parameters
   moqSession_ = std::move(moqSession.value());
   moqSession_->start();
+  // TODO: maybe let the caller set max subscribes.  Any client that publishes
+  // via relay needs to support subscribes.
+  const uint32_t kDefaultMaxSubscribeId = 100;
   moqSession_->setup(ClientSetup(
       {{kVersionDraftCurrent},
-       {{folly::to_underlying(SetupKey::ROLE),
+       {{folly::to_underlying(SetupKey::ROLE), "", folly::to_underlying(role)},
+        {folly::to_underlying(SetupKey::MAX_SUBSCRIBE_ID),
          "",
-         folly::to_underlying(role)}}}));
+         kDefaultMaxSubscribeId}}}));
   co_await moqSession_->setupComplete();
 }
 

moxygen/MoQSession.cpp

@@ -202,6 +202,7 @@ void MoQSession::onClientSetup(ClientSetup clientSetup) {
     receivedSetup_.cancel();
     return;
   }
+  peerMaxSubscribeID_ = getMaxSubscribeIdIfPresent(clientSetup.params);
   receivedSetup_.signal();
   controlMessages_.enqueue(std::move(clientSetup));
   setupComplete().scheduleOn(evb_).start();
@@ -511,6 +512,12 @@ folly::coro::Task<
 MoQSession::subscribe(SubscribeRequest sub) {
   XLOG(DBG1) << __func__ << " sess=" << this;
   auto fullTrackName = sub.fullTrackName;
+  if (nextSubscribeID_ >= peerMaxSubscribeID_) {
+    XLOG(WARN) << "Issuing subscribe that will fail; nextSubscribeID_="
+               << nextSubscribeID_
+               << " peerMaxSubscribeID_=" << peerMaxSubscribeID_
+               << " sess=" << this;
+  }
   auto subID = nextSubscribeID_++;
   sub.subscribeID = subID;
   sub.trackAlias = sub.subscribeID;