request.setRemoteAddr("192.168.1.100");
        request.addHeader("X-Forwarded-For", "203.0.113.50");
        request.addHeader("X-Real-IP", "203.0.113.75");
        // Should return remoteAddr, not the spoofed headers
        assertEquals("192.168.1.100", rateLimitHelper.getClientIp(request));
    }

    @Test
    public void test_blockIp() {
        rateLimitHelper.blockIp("192.168.1.100", 1000L);

## Retrying Requests

Sometimes connections fail: either a pooled connection was stale and disconnected, or the webserver itself couldn’t be reached. OkHttp will retry the request with a different route if one is available.

## [Calls](https://square.github.io/okhttp/5.x/okhttp/okhttp3/-call/)

  /**
   * Returns a fluent iterable that combines two iterables. The returned iterable has an iterator
   * that traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input
   * iterator supports it.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Stream#concat}.

  /**
   * Returns a fluent iterable that combines two iterables. The returned iterable has an iterator
   * that traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input
   * iterator supports it.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Stream#concat}.

        assertDoesNotThrow(() -> bufferManager.cleanup());

        // After cleanup, all regions should be released (but the count may not match exactly
        // if some regions were pooled rather than immediately released)
        assertTrue(bufferManager.getTotalReleased() > 0, "Some regions should be released during cleanup");
        assertEquals(allocatedBeforeCleanup, bufferManager.getTotalReleased(),

## Version 4.4.1

_2020-03-08_

 *  Fix: Don't reuse a connection on redirect if certs match but DNS does not. For better
    locality and performance OkHttp attempts to use the same pooled connection across redirects and
    follow-ups. It independently shares connections when the IP addresses and certificates match,
    even if the host names do not. In 4.4.0 we introduced a regression where we shared a connection

  }

  /**
   * Combines two iterables into a single iterable. The returned iterable has an iterator that
   * traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input
   * iterator supports it.
   *

    // Second call attempts the pooled connection, and it fails. Then it retries a new route which
    // succeeds.
    val response2 = client.newCall(request).execute()
    assertThat(response2.body.string()).isEqualTo("abc")
    assertThat(server.takeRequest().exchangeIndex).isEqualTo(1) // Pooled connection.
    assertThat(server.takeRequest().exchangeIndex).isEqualTo(0) // New connection.

 * **Exchange** carries a single HTTP request/response pair.

 * **ExchangeFinder** chooses which connection carries each exchange. Where possible it will use the same connection for all exchanges in a single call. It prefers reusing pooled connections over establishing new connections.      

#### Per-Connection Locks

If there's a problem with the connection, OkHttp will select another route and try again. This allows OkHttp to recover when a subset of a server's addresses are unreachable. It's also useful when a pooled connection is stale or if the attempted TLS version is unsupported.