OkHttp DNS over HTTPS Implementation
====================================

This module is an implementation of [DNS over HTTPS][1] using OkHttp.

### Download

```kotlin
testImplementation("com.squareup.okhttp3:okhttp-dnsoverhttps:4.12.0")
```

### Usage

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

import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import javax.net.SocketFactory;
import jnr.unixsocket.UnixSocketChannel;

/** Impersonate TCP-style SocketFactory over UNIX domain sockets. */
public final class UnixDomainSocketFactory extends SocketFactory {
  private final File path;

  public UnixDomainSocketFactory(File path) {
    this.path = path;
  }

      assertThat(recorded.headers["Content-Length"]).isEqualTo("0")
    }
    assertThat(recorded.headers["HTTP2-Settings"]).isNotNull()
    assertThat(recorded.headers["Upgrade"]).isEqualTo("h2c") // HTTP/2 over plaintext!
    assertThat(recorded.headers["User-Agent"]!!).matches(Regex("Java-http-client/.*"))
  }

import okio.ByteString.Companion.encodeUtf8
import okio.Options

/**
 * A decoded [mapping table] that can perform the [mapping step] of IDNA processing.
 *
 * This implementation is optimized for readability over efficiency.
 *
 * This implements non-transitional processing by preserving deviation characters.
 *
 * This implementation's STD3 rules are configured to `UseSTD3ASCIIRules=false`. This is

Request newYorkTimesRequest = new Request.Builder()
    .url("https://www.nytimes.com/")
    .build();
client.newCall(newYorkTimesRequest).enqueue(new Callback() {
  ...
});
```

Running this race over home WiFi shows the Times (`0002`) completes just slightly sooner than the Post (`0001`):

```
0001 https://www.washingtonpost.com/
0001 0.000 callStart
0002 https://www.nytimes.com/
0002 0.000 callStart

      }
    } else {
      super.getSelectedProtocol(sslSocket)
    }

  companion object {
    val isSupported: Boolean =
      try {
        // Trigger an early exception over a fatal error, prefer a RuntimeException over Error.
        Class.forName("org.bouncycastle.jsse.provider.BouncyCastleJsseProvider", false, javaClass.classLoader)

        true
      } catch (_: ClassNotFoundException) {
        false
      }

In OkHttp we expose a blocking API over a framed protocol. This document explains the code and policy that makes that work.

### Threads

#### Application's calling thread

import okhttp3.mockwebserver.MockResponse;
import okhttp3.mockwebserver.MockWebServer;

/**
 * Create UNIX domain sockets for MockWebServer and OkHttp and connect 'em together. Note that we
 * cannot do TLS over domain sockets.
 */
public class ClientAndServer {
  public void run() throws Exception {
    File socketFile = new File("/tmp/ClientAndServer.sock");
    socketFile.delete(); // Clean up from previous runs.

import javax.net.ServerSocketFactory;
import jnr.unixsocket.UnixServerSocketChannel;
import jnr.unixsocket.UnixSocketAddress;
import jnr.unixsocket.UnixSocketChannel;

/** Impersonate TCP-style ServerSocketFactory over UNIX domain sockets. */
public final class UnixDomainServerSocketFactory extends ServerSocketFactory {
  private final File path;

  public UnixDomainServerSocketFactory(File path) {
    this.path = path;
  }

import java.net.InetAddress
import java.net.UnknownHostException
import okhttp3.HttpUrl.Companion.toHttpUrl
import okhttp3.OkHttpClient

/**
 * Temporary registry of known DNS over HTTPS providers.
 *
 * https://github.com/curl/curl/wiki/DNS-over-HTTPS
 */
object DohProviders {
  private fun buildGoogle(bootstrapClient: OkHttpClient): DnsOverHttps {
    return DnsOverHttps.Builder()
      .client(bootstrapClient)