server.enqueue(
      MockResponse.Builder()
        .body("abc")
        .addHeader("Content-Type: text/plain")
        .build(),
    )

    // Make a request from client to server. It should succeed certificate checks (unfortunately the
    // rogue CA is trusted) but it should fail certificate pinning.
    val request =
      Request.Builder()
        .url(server.url("/"))
        .build()

    assertFailsWith<InterruptedIOException> {
      // If this succeeds, too many requests were made.
      client.newCall(request).execute()
    }
  }

  /**
   * Make a request with two routes. The first route will time out because it's connecting to a
   * special address that never connects. The automatic retry will succeed.
   */
  @Test
  fun connectTimeoutsAttemptsAlternateRoute() {

        response.body.string()
      }
    }

    // The second call succeeds.
    val call2 = client.newCall(Request(server.url("/")))
    call2.execute().use { response ->
      assertThat(
        response.body.string(),
      ).isEqualTo("b")
    }

    // Calls succeed after the degraded pong timeout because the degraded pong was received.

import okhttp3.internal.okHttpName

/**
 * Speculatively connects to each IP address of a target address, returning as soon as one of them
 * connects successfully. This kicks off new attempts every 250 ms until a connect succeeds.
 */
internal class FastFallbackExchangeFinder(
  override val routePlanner: RoutePlanner,
  private val taskRunner: TaskRunner,
) : ExchangeFinder {
  private val connectDelayNanos = TimeUnit.MILLISECONDS.toNanos(250L)

      "s/version = \".*\"/version = \"$NEXT_VERSION\"/g" \
      build.gradle.kts
    git commit -am "Prepare next development version."
    git push
    ```

7. Confirm the [GitHub Actions][github_actions] publish job succeeded.

[github_actions]: https://github.com/square/okhttp/actions

          "sha256" -> {
            if (sha256 == null) sha256 = peerCertificate.sha256Hash()
            if (pin.hash == sha256) return // Success!
          }
          "sha1" -> {
            if (sha1 == null) sha1 = peerCertificate.sha1Hash()
            if (pin.hash == sha1) return // Success!
          }
          else -> throw AssertionError("unsupported hashAlgorithm: ${pin.hashAlgorithm}")
        }
      }
    }

      return
    }

    try {
      testHttpUrl(testData)
      if (KNOWN_FAILURES.contains(testData.toString())) {
        System.err.println("Expected failure but was success: $testData")
      }
    } catch (e: Throwable) {
      if (KNOWN_FAILURES.contains(testData.toString())) {
        System.err.println("Ignoring known failure: $testData")
        e.printStackTrace()
      } else {

must block on writing I/O. We can't return from a write until we've pushed its bytes onto the socket. Otherwise, if the write fails we are unable to deliver its IOException to the application. We would have told the application layer that the write succeeded, but it didn't!

The application-layer can also do blocking reads. If the application asks to read and there's nothing available, we need to hold that thread until either the bytes arrive, the stream is closed, or a timeout elapses. If we...

   * leaking resources callers must [close the response body][ResponseBody] or the response.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not
   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP
   * response code like 404 or 500.
   *

      val uri = url.toUri()
      if (uri.host == null) return immutableListOf(Proxy.NO_PROXY)

      // Try each of the ProxySelector choices until one connection succeeds.
      val proxiesOrNull = address.proxySelector.select(uri)
      if (proxiesOrNull.isNullOrEmpty()) return immutableListOf(Proxy.NO_PROXY)

      return proxiesOrNull.toImmutableList()
    }