给OkHttp Client添加socks代理
Okhttp的使用没有httpClient广泛，网上关于Okhttp设置代理的方法很少，这篇文章完整介绍了需要注意的方方面面。
上一篇博客中介绍了socks代理的入口是创建java.net.Socket时传入一个java.net.Porxy对象。 OkHttp client通过OkHttpClient.Builder创建，可以通过定制javax.net.ssl.SSLSocketFactory和java.net.SocketFactory来实现socks代理。
定制SocketFactory
JDK中默认的是java.net.DefaultSocketFactory,它是包可见的，没法扩展，所以只能用java.net.SocketFactory扩展，没有什么其他好的招数，这个过程其实有点繁琐。
public class ProxySocketFactory extends SocketFactory {
private ProxyConfigProvider proxyConfigProvider;
public ProxySocketFactory(ProxyConfigProvider proxyConfigProvider) {
this.proxyConfigProvider = proxyConfigProvider;
}
@Override
public Socket createSocket() throws IOException {
ProxyConfig proxyConfig = proxyConfigProvider.getProxyConfig();
if (proxyConfig != null) {
return new Socket(proxyConfig.getProxy());
} else {
return new Socket();
}
}
public Socket createSocket(String host, int port)
throws IOException, UnknownHostException {
Socket socket = createSocket();
try {
socket.connect(new InetSocketAddress(host, port));
} catch (IOException e) {
socket.close();
throw e;
}
return socket;
}
public Socket createSocket(InetAddress address, int port)
throws IOException {
Socket socket = createSocket();
try {
socket.connect(new InetSocketAddress(address, port));
} catch (IOException e) {
socket.close();
throw e;
}
return socket;
}
public Socket createSocket(String host, int port,
InetAddress clientAddress, int clientPort)
throws IOException, UnknownHostException {
Socket socket = createSocket();
try {
socket.bind(new InetSocketAddress(clientAddress, clientPort));
socket.connect(new InetSocketAddress(host, port));
} catch (IOException e) {
socket.close();
throw e;
}
return socket;
}
public Socket createSocket(InetAddress address, int port,
InetAddress clientAddress, int clientPort)
throws IOException {
Socket socket = createSocket();
try {
socket.bind(new InetSocketAddress(clientAddress, clientPort));
socket.connect(new InetSocketAddress(address, port));
} catch (IOException e) {
socket.close();
throw e;
}
return socket;
}
}
上面代码这么长，并不是随便写的，也省不了。我参考了DefaultSocketFactory里面创建Socket对象的各个构造函数，保证了ProxySocketFactory的跟DefaultSocketFactory对应方法的行为完全一致，只是在创建socket时用了代理而已。简单一句话：只要传入了IP地址和端口，就会直接发起连接。
对SSL socket工厂的定制同样繁琐。不是简单的继承（继承搞不定），而是采用包装模式，用原来的SSLSocketFactory来实现与代理无关的方法。
public class ProxySSLSocketFactory extends SSLSocketFactory {
private ProxyConfigProvider configProvider;
private SSLSocketFactory socketFactory;
public ProxySSLSocketFactory(ProxyConfigProvider configProvider, SSLSocketFactory socketFactory) {
this.configProvider = configProvider;
this.socketFactory = socketFactory;
}
@Override
public String[] getDefaultCipherSuites() {
return socketFactory.getDefaultCipherSuites();
}
@Override
public String[] getSupportedCipherSuites() {
return socketFactory.getSupportedCipherSuites();
}
public Socket createSocket()
throws IOException {
ProxyConfig proxyConfig = configProvider.getProxyConfig();
if (proxyConfig != null) {
return new Socket(proxyConfig.getProxy());
} else {
return new Socket();
}
}
public Socket createSocket(String host, int port)
throws IOException {
Socket socket = createSocket();
try {
return socketFactory.createSocket(socket, host, port, true);
} catch (IOException e) {
socket.close();
throw e;
}
}
public Socket createSocket(Socket s, String host,
int port, boolean autoClose)
throws IOException {
//TODO 无法代理
return socketFactory.createSocket(s, host, port, autoClose);
}
public Socket createSocket(InetAddress address, int port)
throws IOException {
Socket socket = createSocket();
try {
return socketFactory.createSocket(socket, address.getHostAddress(), port, true);
} catch (IOException e) {
socket.close();
throw e;
}
}
public Socket createSocket(String host, int port,
InetAddress clientAddress, int clientPort)
throws IOException {
Socket socket = createSocket();
try {
socket.bind(new InetSocketAddress(clientAddress, clientPort));
return socketFactory.createSocket(socket, host, port, true);
} catch (IOException e) {
socket.close();
throw e;
}
}
public Socket createSocket(InetAddress address, int port,
InetAddress clientAddress, int clientPort)
throws IOException {
Socket socket = createSocket();
try {
socket.bind(new InetSocketAddress(clientAddress, clientPort));
return socketFactory.createSocket(socket, address.getHostAddress(), port, true);
} catch (IOException e) {
socket.close();
throw e;
}
}
}注意，其中有一个方法是无法使用代理的：Socket createSocket(Socket s, String host,int port, boolean autoClose)，因为传入的已经是一个创建好的Socket，所以使用这个方法，要注意你的组件有没有用到这个方法，如果用到了，代理的功能需要在这个方法的调用者那一层去实现。我测试OkHttp client是没有用到这个方法的。
创建OkHttpClient对象
两个工厂类设计好了之后，下面就是运用他们创建OkHttpClient对象。
public OkHttpClient buildOkHttpClient() {
OkHttpClient httpClient = new OkHttpClient.Builder()
.sslSocketFactory(new ProxySSLSocketFactory(proxyProvider, NOP_TLSV12_SSL_CONTEXT.getSocketFactory()), NOP_TRUST_MANAGER)
.socketFactory(new ProxySocketFactory(proxyProvider))
.hostnameVerifier(NOP_HOSTNAME_VERIFIER)
.connectTimeout(DEFAULT_CONNECTION_TIMEOUT, TimeUnit.SECONDS)
.writeTimeout(DEFAULT_CONNECTION_TIMEOUT, TimeUnit.SECONDS)
.readTimeout(DEFAULT_CONNECTION_TIMEOUT, TimeUnit.SECONDS)
.addInterceptor(new OkHttpProxyInterceptor())
.build();
return httpClient;
}上面的方法注意两行：
.sslSocketFactory(xxx)
.socketFactory(xxx)其他代码，有对超时的设置.xxxTimeout()，这里不赘述，还有对https请求证书的设置以及对socks密码的设置，稍后详解
设置https需要注意的地方
NOP_TRUST_MANAGER对象设置为信任任何证书：
public static final X509TrustManager NOP_TRUST_MANAGER = new X509TrustManager() {
@Override
public void checkClientTrusted(X509Certificate[] x509Certificates, String s)
throws CertificateException {
}
@Override
public void checkServerTrusted(X509Certificate[] x509Certificates, String s)
throws CertificateException {
}
@Override
public X509Certificate[] getAcceptedIssuers() {
return new X509Certificate[0];
}
};NOP_HOSTNAME_VERIFIER对象设置为信任任何域名：
public static final HostnameVerifier NOP_HOSTNAME_VERIFIER = new HostnameVerifier() {
@Override
public boolean verify(String s, SSLSession sslSession) {
return true;
}
};https的协议版本可能不支持TLSv1
上面两条设置网上很多文档都会介绍，重点需要关注的是NOP_TLSV12_SSL_CONTEXT对象。
干货来了：JDK使用的HTTPS协议版本参考这里-diagnosing-tls,-ssl,-and-https，可以看到在JDK7以前，默认都是TLSv1，JDK8才默认采用TLSv1.2，而很多较新的网站都已经禁用HTTPS使用TLSv1握手了，认为这个协议已经不够安全（例如，我在给minio-java client添加proxy支持时，发现minio-server就这么干的）。所以你用java去发起HTTPS连接经常会出现SSL相关的异常，大部分异常信息根本看不懂。
所以，需要在代码里面指定https使用TLSv1.2：
static {
try {
NOP_TLSV12_SSL_CONTEXT = SSLContext.getInstance("TLSv1.2");
NOP_TLSV12_SSL_CONTEXT.init(null, new TrustManager[]{NOP_TRUST_MANAGER}, new java.security.SecureRandom());
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (KeyManagementException e) {
e.printStackTrace();
}
}实际上也可以通过：
System.setProperty("https.protocols","TLSv1.2");//在创建任何SSLSocketFactory之前调用或者设置虚拟机参数：
-Dhttps.protocols=TLSv1.2,TLSv1.1,TLSv1放在前面的协议会被优先选用
检测https支持的协议版本
如果出现SSL相关异常，但是又不确定是不是协议版本导致的，可以有几个工具进行检验：
nmap : nmap --script ssl-enum-ciphers -p 443 baidu.com,在我机器上看到：
PORT STATE SERVICE
443/tcp open https
| ssl-enum-ciphers:
| SSLv3:
| ciphers:
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - A
| compressors:
| NULL
| cipher preference: server
| warnings:
| CBC-mode cipher in SSLv3 (CVE-2014-3566)
| TLSv1.0:
| ciphers:
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - A
| compressors:
| NULL
| cipher preference: server
| TLSv1.1:
| ciphers:
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - A
| compressors:
| NULL
| cipher preference: server
| warnings:
| Weak cipher RC4 in TLSv1.1 or newer not needed for BEAST mitigation
| TLSv1.2:
| ciphers:
| TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (secp256r1) - A
| TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - A
| compressors:
| NULL
| cipher preference: server
| warnings:
| Weak cipher RC4 in TLSv1.1 or newer not needed for BEAST mitigation
|_ least strength: A设置Socks的用户名和密码
OkHttp提供了拦截器的机制okhttp3.Interceptor，可以定制http发起的流程。
设置密码有两种方式：一种是设置全局的，另一种是按线程隔离（也是就是按请求隔离），不同请求可以设置不同的用户名和密码，详细介绍以及部分代码见我的上一篇博客-给HttpClient添加Socks代理。
注意到上面代码有这么一行：
.addInterceptor(new OkHttpProxyInterceptor())就是设置一个拦截器。
private class OkHttpProxyInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
ProxyConfig proxyConfig = ProxyHttpClientBuilder.this.getProxyConfig();
boolean clearCredentials = false;
if (proxyConfig != null) {
if (proxyConfig.getAuthentication() != null) {
ThreadLocalProxyAuthenticator.setCredentials(proxyConfig.getAuthentication());
clearCredentials = true;
}
}
try {
return chain.proceed(chain.request());
} finally {
if (clearCredentials) {
ThreadLocalProxyAuthenticator.clearCredentials();
}
}
}
}ThreadLocalProxyAuthenticator,ProxyConfig等类见上一篇博客。