How to modify http request headers？

[bcfhe]

Is it possible to modify the http request headers?

[Danstahrg]

Hi,

For most headers, you can use the OkHttp APIs to modify the request headers. There's a few headers with special treatment, such as accept-encoding and user-agent, if you're seeing an inconsistent behavior between plain OkHttp and this library please provide more details.

[bcfhe]

With code like below okhttpclient communicates via HTTP/2 even though the google site supports quic.

import android.content.ClipData
import android.content.ClipboardManager
import android.content.Context
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.google.net.cronet.okhttptransport.CronetInterceptor
import okhttp3.*
import org.chromium.net.CronetEngine
import java.io.IOException

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val engine = CronetEngine.Builder(applicationContext).build()
        val callFactory = OkHttpClient().newBuilder()
            .addInterceptor(CronetInterceptor.newBuilder(engine).build())
            .build()
        val request=Request.Builder()
            .url("https://www.google.com/")
            .header("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:98.0) Gecko/20100101 Firefox/98.0")
            .header("Accept-Encoding","gzip, deflate, br")
            .header("Accept","text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8")
            .build()
        callFactory.newCall(request).enqueue(object : Callback {
            override fun onFailure(call: Call, e: IOException) {
            }

            override fun onResponse(call: Call, response: Response) {
                runOnUiThread{
                    var contentEncoding=response.headers.get("Content-Encoding")
                    if(contentEncoding.isNullOrEmpty()){
                        contentEncoding="identity"
                    }
                    Toast.makeText(applicationContext,response.protocol.toString()+"\n"+contentEncoding+"\nEncoding:"+response.toString(),
                        Toast.LENGTH_SHORT).show()
                    copyToClipboard(applicationContext,"",response.body!!.string())
                }
            }
        })
    }
    fun copyToClipboard(context: Context, label: String?, text: String?) {
        val clipboardManager: ClipboardManager =
            context.getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
                ?: return
        clipboardManager.setPrimaryClip(ClipData.newPlainText(label, text))
    }
}

[Danstahrg]

Ah, right, there's a few things that may come into play here:

• In order to use QUIC you need to enable it on your Cronet Engine.
• You should provide QUIC hints to let Cronet know that a particular host supports QUIC.
• If you don't we'll pick that information up from alt-svc headers and will use quic the next time you connect to the host. However, note that due to connection pooling the reconnect might not happen immediately so subsequent request to the same host might still use h2.
• Either way, we also suggest that you enable on-disk cache to persist "these servers support QUIC" signals.

Unrelated to QUIC support - you shouldn't set Accept-Encoding manually. Cronet sets these automatically depending on you Cronet engine configuration (e.g. enableBrotli) and decodes the server response transparently.

[bcfhe]

Enabling QUIC and setting QUIC Hints solved this problem.

I also want to use QUIC on non-Android OS such as Linux. Can this library be used on Linux and Windows?

[ag2s20150909]

Enabling QUIC and setting QUIC Hints solved this problem.

I also want to use QUIC on non-Android OS such as Linux. Can this library be used on Linux and Windows?

https://github.com/chromium/chromium/blob/main/components/cronet/build_instructions.md

[Danstahrg]

Caveat to that: The only officially supported platform is Android.

[bcfhe]

On Linux and Windows, it seems difficult to use this library. So I will use this only on android. Thank you for your advice.