Fix bug where we constantly cycled network stack when on network with PAC proxy.

app/src/main/java/org/thoughtcrime/securesms/push/SignalServiceNetworkAccess.kt

@@ -2,6 +2,7 @@ package org.thoughtcrime.securesms.push
 
 import android.content.Context
 import android.net.ConnectivityManager
+import android.net.ProxyInfo
 import android.net.Uri
 import androidx.core.content.ContextCompat
 import com.google.i18n.phonenumbers.PhoneNumberUtil
@@ -143,9 +144,15 @@ class SignalServiceNetworkAccess(context: Context) {
     private fun getSystemHttpProxy(context: Context): HttpProxy? {
       val connectivityManager = ContextCompat.getSystemService(context, ConnectivityManager::class.java) ?: return null
 
-      return connectivityManager
+      val proxyInfo = connectivityManager
         .activeNetwork
         ?.let { connectivityManager.getLinkProperties(it)?.httpProxy }
+
+      return proxyInfo.toApplicableSystemHttpProxy()
+    }
+
+    fun ProxyInfo?.toApplicableSystemHttpProxy(): HttpProxy? {
+      return this
         ?.takeIf { !it.exclusionList.contains(BuildConfig.SIGNAL_URL.stripProtocol()) }
         // NB: Edit carefully, dear reader, as the line below is written from hard won experience.
         // It turns out, that despite being documented *nowhere*, if a PAC file is set
@@ -156,7 +163,7 @@ class SignalServiceNetworkAccess(context: Context) {
         // So, if we do not explicitly check that a PAC file is not set, the proxy
         //   we pass to libsignal may be syntactically invalid, and the user may be
         //   rendered unable to connect.
-        ?.takeIf { proxyInfo -> proxyInfo.pacFileUrl.equals(Uri.EMPTY) }
+        ?.takeIf { it.pacFileUrl == Uri.EMPTY }
         ?.let { proxy -> HttpProxy(proxy.host, proxy.port) }
     }
   }