Requests are resolved through HTTP2

[araujo-luis]

I'm trying to implement HTTP/3 with QUIC support in my Android app using OkHttp and the Cronet transport. However, all requests are being made under HTTP/2. I have used different devices with different versions. I've tried with Retrofit as well and same result.

The server I'm reaching out does support HTTP3 I've tested it on web and it works fine.

private val engine = CronetEngine.Builder(MainActivity.appContext).enableHttpCache(CronetEngine.Builder.HTTP_CACHE_DISK, 10 * 1024 * 1024)
    .build()

    private val callFactory = OkHttpClient.Builder()
        .addInterceptor(CronetInterceptor.newBuilder(engine).build())
    .build();

private fun getRequest(url: String): JSONObject? {
        val request: Request = Request.Builder()
            .url(url)
            .build()

        val response = callFactory.newCall(request).execute()
        return response.body?.string()?.let { JSONObject(it) }
    }

[ag2s20150909]

https://developer.android.com/guide/topics/connectivity/cronet/reference/org/chromium/net/CronetEngine.Builder.html#addQuicHint(java.lang.String,%20int,%20int)

[araujo-luis]

https://developer.android.com/guide/topics/connectivity/cronet/reference/org/chromium/net/CronetEngine.Builder.html#addQuicHint(java.lang.String,%20int,%20int)

Yes, I tried that. I realized my OkHttp config was missing QUIC protocol, by default is not enabled. https://github.com/google/cronet-transport-for-okhttp/pull/23

[ag2s20150909]

but OkHttp config has no effect on Cronet.

[araujo-luis]

but OkHttp config has no effect on Cronet.

It does.

  * QUIC is not natively supported by OkHttp, but provided to allow a theoretical interceptor that
  * provides support.

https://github.com/square/okhttp/blob/337b1b1b19a702916798096766b80e4b3700db01/okhttp/src/commonMain/kotlin/okhttp3/Protocol.kt#L77-L85

[Danstahrg]

The TL;DR of how the http2/3 negotiation works is covered here: https://github.com/GoogleChromeLabs/cronet-sample/blob/master/android/app/src/main/java/com/google/samples/cronet_sample/CronetApplication.java#L77. If you enable the on-disk cache this should only affect the very first few requests to a server, subsequent connections will respect the alt-svc signal and use QUIC.

As for protocols configuration in OkHttp (https://square.github.io/okhttp/4.x/okhttp/okhttp3/-ok-http-client/-builder/protocols/), this library bypasses the config and setting it has no effect.

Yes, I tried that. I realized my OkHttp config was missing QUIC protocol, by default is not enabled.

Which Cronet version are you using? This suggests an old one, as the default was changed in mid-2020: https://crrev.com/c/2168553

[araujo-luis]

The TL;DR of how the http2/3 negotiation works is covered here: https://github.com/GoogleChromeLabs/cronet-sample/blob/master/android/app/src/main/java/com/google/samples/cronet_sample/CronetApplication.java#L77. If you enable the on-disk cache this should only affect the very first few requests to a server, subsequent connections will respect the alt-svc signal and use QUIC.

As for protocols configuration in OkHttp (https://square.github.io/okhttp/4.x/okhttp/okhttp3/-ok-http-client/-builder/protocols/), this library bypasses the config and setting it has no effect.

Yes, I tried that. I realized my OkHttp config was missing QUIC protocol, by default is not enabled.

Which Cronet version are you using? This suggests an old one, as the default was changed in mid-2020: https://crrev.com/c/2168553

Thanks for your help!

    implementation 'com.google.net.cronet:cronet-okhttp:0.1.0'
    implementation 'com.google.android.gms:play-services-cronet:18.0.1'

Seems like you are right, I just removed the protocols I've defined on OkHttpBuilder, and requests are being resolved through QUIC. Not sure what configuration I had yesterday. My guess is that the first requests were resolved with HTTP2 as you pointed out (the one I was debugging).

                // Cronet tries to use both protocols and it's nondeterministic which
                // one will be used for the first few requests. As soon as Cronet is aware that
                // a server supports QUIC, it will always attempt to use it first