Using OkHttp Interceptor: Redundant User Agents

[shalfknight]

Hi folks,

when specifying a particular user agent value in my http header via an OKHttp3 interceptor, e.g. with MY_CUSTOM_USER_AGENT_RIGHT_HERE, the user agent field seems to get mixed with the default http.agent system property defined in LazyHeaders.java:

String defaultUserAgent = System.getProperty("http.agent");

So the result looks as follows and thereby the request to my backend (infrastructure) starts failing (as my backend only expects and accepts the defined value):

Dalvik/2.1.0 (Linux; U; Android 9; Android SDK built for x86 Build/PSR1.180720.075); MY_CUSTOM_USER_AGENT_RIGHT_HERE

Imho it seems that both user agent values are getting mixed in the end by the OkHttpStreamFetcher.java in loadData() when the built up request + client are coming together. Quite similar to a problem ~ 3 years ago: #546

Issue details / Repro steps / Use case background:

My Interceptor:

import okhttp3.Interceptor
import okhttp3.Response

class UserAgentInterceptor : Interceptor {

    override fun intercept(chain: Interceptor.Chain): Response = chain.proceed(
            chain.request()
                    .newBuilder()
                    .addHeader("User-Agent", "MY_CUSTOM_USER_AGENT_RIGHT_HERE")
                    .build())
}

My used Glide Module:

import android.content.Context
import com.bumptech.glide.Glide
import com.bumptech.glide.Registry
import com.bumptech.glide.annotation.GlideModule
import com.bumptech.glide.integration.okhttp3.OkHttpUrlLoader.Factory
import com.bumptech.glide.load.model.GlideUrl
import com.bumptech.glide.module.AppGlideModule
import okhttp3.Dispatcher
import okhttp3.OkHttpClient
import java.io.InputStream

@GlideModule
class OkHttpGlideModule : AppGlideModule() {

    override fun registerComponents(context: Context, glide: Glide, registry: Registry) {
        val client = OkHttpClient.Builder()
                .addInterceptor(ConnectivityInterceptor(context, false))
                .build()
        registry.replace(GlideUrl::class.java, InputStream::class.java, Factory(client))
    }
}

Glide load line:
I'm using data binding to set the loading mechanism for ImageViews

object ImageViewBinding {

    @JvmStatic
    @BindingAdapter(value = ["url", "default"], requireAll = false)
    fun setImageUrl(view: ImageView, url: String?, @DrawableRes default: Drawable?) {
        default?.let {
            view.setImageDrawable(it)
        }

        url?.let {
            Glide.with(view.context).load(it).placeholder(default).into(view)
        }
    }

Glide Version:
Glide 4.9, latest release

Integration libraries:
Glide-OkHttp3-integration, 4.9 as well

Other libraries:
OkHttp3, 3.12.1

Device/Android Version:
Can be tested on an AVD Pie x86 image but also reproducible on Samsung S6, S7, Google Pixel or Huawei devices. Imho not device specific related

Question:

• Is it required to set the user agent somewhere else instead of using an interceptor? -> From your point of view works as designed? If yes, what would be the right way?
• Or Is this actually a bug that such conflicts should not occur?

[technoir42]

Your requests have 2 User-Agent headers since Glide adds one and you add one too.
You have to use header(key, value) instead of addHeader(key, value) to replace the existing header.

[shalfknight]

Thx!

So simple it is by just knowing that addHeader starts working like a combine, not replacing previous values.

Final solution:

class UserAgentInterceptor : Interceptor {

    override fun intercept(chain: Interceptor.Chain): Response = chain.proceed(
            chain.request()
                    .newBuilder()
                    .header("User-Agent", "MY_CUSTOM_USER_AGENT_RIGHT_HERE")
                    .build())
}

Thx for the fast response time and your patience!

May the next guy who is facing that "problem" be guided by this thread.

Problem solved!