简介

本文将展示如何使用“全部接受”SSL支持配置Apache HttpClient 4。目标很简单 - 使用没有有效证书的HTTPS URL。

SSLPeerUnverifiedException

如果不使用HttpClient配置SSL ，以下测试（使用HTTPS URL）将失败：

public class RestClientLiveManualTest {
 
    @Test(expected = SSLPeerUnverifiedException.class)
    public void test() 
      throws ClientProtocolException, IOException {
  
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String urlOverHttps
        ="https://localhost:8082/httpclient-simple)";

HttpGet getMethod = new HttpGet(urlOverHttps);
         
        HttpResponse response = httpClient.execute(getMethod);
        assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    }
}

异常报错为：

javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated
    at sun.security.ssl.SSLSessionImpl.getPeerCertificates(SSLSessionImpl.java:397)
    at org.apache.http.conn.ssl.AbstractVerifier.verify(AbstractVerifier.java:126)
    ...

该javax.net.ssl.SSLPeerUnverifiedException，该报错产生原因，当无法有效为URL建立信任链的时候。

配置通用的SSL（HttpClient <4.3）

现在让我们将HTTPClient配置为信任所有证书，无论其有效性如何：

@Test
public final void test() 
  throws GeneralSecurityException {
    HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
    CloseableHttpClient httpClient = (CloseableHttpClient) requestFactory.getHttpClient();
 
    TrustStrategy acceptingTrustStrategy = (cert, authType) -> true;
    SSLSocketFactory sf = new SSLSocketFactory(acceptingTrustStrategy, ALLOW_ALL_HOSTNAME_VERIFIER);
    httpClient.getConnectionManager().getSchemeRegistry().register(new Scheme("https", 8443, sf));
 
    ResponseEntity<String> response = new RestTemplate(requestFactory).
      exchange(urlOverHttps, HttpMethod.GET, null, String.class);
    assertThat(response.getStatusCode().value(), equalTo(200));
}

随着acceptingTrustStrategy 配置了 true的测试通过，client能够消费的HTTPS URL。

配置通用的SSL（HttpClient 4.4及更高版本）

使用新的HTTPClient，现在我们有了一个增强的，重新设计的默认SSL主机名验证程序。此外，通过引入SSLConnectionSocketFactory和RegistryBuilder，可以轻松构建SSLSocketFactory。所以我们可以编写上面的测试用例，如：

@Test
public final void test()
  throws GeneralSecurityException {
    TrustStrategy acceptingTrustStrategy = (cert, authType) -> true;
    SSLContext sslContext = SSLContexts.custom().loadTrustMaterial(null, acceptingTrustStrategy).build();
    SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext, 
      NoopHostnameVerifier.INSTANCE);
     
    Registry<ConnectionSocketFactory> socketFactoryRegistry = 
      RegistryBuilder.<ConnectionSocketFactory> create()
      .register("https", sslsf)
      .register("http", new PlainConnectionSocketFactory())
      .build();
 
    BasicHttpClientConnectionManager connectionManager = 
      new BasicHttpClientConnectionManager(socketFactoryRegistry);
    CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(sslsf)
      .setConnectionManager(connectionManager).build();
 
    HttpComponentsClientHttpRequestFactory requestFactory = 
      new HttpComponentsClientHttpRequestFactory(httpClient);
    ResponseEntity<String> response = new RestTemplate(requestFactory)
      .exchange(urlOverHttps, HttpMethod.GET, null, String.class);
    assertThat(response.getStatusCode().value(), equalTo(200));
}

使用SSL 的Spring RestTemplate（HttpClient <4.3）

现在我们已经了解了如何配置具有SSL支持的原始HttpClient，让我们来看看更高级别的方式-Spring RestTemplate。

如果未配置SSL，则以下测试将按预期会抛异常：

@Test(expected = ResourceAccessException.class)
public void test() {
    String urlOverHttps 
      = "https://localhost:8443/httpclient-simple/api/bars/1";
    ResponseEntity<String> response 
      = new RestTemplate().exchange(urlOverHttps, HttpMethod.GET, null, String.class);
    assertThat(response.getStatusCode().value(), equalTo(200));
}

那么让我们配置SSL：

@Test
public void test() 
  throws GeneralSecurityException {
    HttpComponentsClientHttpRequestFactory requestFactory 
      = new HttpComponentsClientHttpRequestFactory();
    DefaultHttpClient httpClient
      = (DefaultHttpClient) requestFactory.getHttpClient();
    TrustStrategy acceptingTrustStrategy = (cert, authType) -> true
    SSLSocketFactory sf = new SSLSocketFactory(
      acceptingTrustStrategy, ALLOW_ALL_HOSTNAME_VERIFIER);
    httpClient.getConnectionManager().getSchemeRegistry()
      .register(new Scheme("https", 8443, sf));
 
    String urlOverHttps ="https://localhost:8443/httpclient-simple/api/bars/1";

    ResponseEntity<String> response = new RestTemplate(requestFactory).
      exchange(urlOverHttps, HttpMethod.GET, null, String.class);
    assertThat(response.getStatusCode().value(), equalTo(200));
}

这与我们为原始HttpClient配置SSL的方式非常相似 - 我们使用SSL支持配置请求工厂，然后我们实例化通过此预配置工厂的模板。

带有SSL 的Spring RestTemplate（HttpClient 4.4）

我们可以使用相同的方式配置我们的RestTemplate：

@Test
public void test() 
throws ClientProtocolException, IOException {
    CloseableHttpClient httpClient
      = HttpClients.custom()
        .setSSLHostnameVerifier(new NoopHostnameVerifier())
        .build();
    HttpComponentsClientHttpRequestFactory requestFactory 
      = new HttpComponentsClientHttpRequestFactory();
    requestFactory.setHttpClient(httpClient);
 
    ResponseEntity<String> response 
      = new RestTemplate(requestFactory).exchange(
      urlOverHttps, HttpMethod.GET, null, String.class);
    assertThat(response.getStatusCode().value(), equalTo(200));
}

总结

本教程讨论了如何为Apache HttpClient配置SSL，以便它能够使用任何HTTPS URL，而不管证书是什么。还说明了Spring RestTemplate的相同配置。

然而，一个重要的事情是，这种策略完全忽略了证书检查 - 这使得它不安全，只能在有意义的地方使用。