How to use multiple DoH providers using okhttp DnsOverHttps package?

Question

Let's say I want to try Cloudflare DoH first and then in case of a failure fall back to Google's DoH, How can I do that?

Using a single provider is pretty straightforward, though.

  val appCache = Cache(File("cacheDir", "okhttpcache"), 10 * 1024 * 1024)
  val bootstrapClient = OkHttpClient.Builder().cache(appCache).build()

  val dns = DnsOverHttps.Builder().client(bootstrapClient)
    .url("https://dns.google/dns-query".toHttpUrl())
    .bootstrapDnsHosts(InetAddress.getByName("8.8.4.4"), InetAddress.getByName("8.8.8.8"))
    .build()

  val client = bootstrapClient.newBuilder().dns(dns).build()

user_1542667 · Answer

You will need to implement your own Dns that chains the calls.

See https://github.com/yschimke/okurl/blob/0abaa8510dd5466d5e9a08ebe33a009c491749bf/src/main/kotlin/com/baulsupp/okurl/network/DnsSelector.kt for an example that delegates to another Dns implementation. You will need two delegates and call one and then conditionally the other one.

How to use multiple DoH providers using okhttp DnsOverHttps package?

1 Answers