![流程](/images/20181023_liucheng.jpg "流程") > 函数计算（Function Compute）是事件驱动的全托管计算服务。函数计算无需租用和管理24小时运行的服务器(Serverless)，无需搭建复杂的服务器环境，只需编写代码并上传就可以了，只需要为代码实际运行消耗的资源付费，非常便宜。 > 函数计算可以选择运行区域，也就是说，我们可以将函数运行的服务器区域选择到香港或者是美国，如此会带来什么样的好处，只可意会，不可言传。那么能否利用云函数写一个Proxy软件呢？请看本文！ ## 在阿里云上新建函数计算我们需要建立一个云函数，和一个HTTP触发器。此过程请参考阿里云官网，我就不详细赘述。[官网在此](https://www.aliyun.com/product/fc "官网在此") ## Netty服务端Handle代码 ```kotlin package cn.wycode.lambda.proxy.inbound import cn.wycode.lambda.proxy.config.AliyunConfig import cn.wycode.lambda.proxy.outbound.ProxyOutboundInitializer import io.netty.bootstrap.Bootstrap import io.netty.buffer.ByteBuf import io.netty.buffer.Unpooled import io.netty.channel.* import io.netty.handler.codec.http.* import io.netty.util.CharsetUtil class ProxyInboundHandler(val aliyunConfig: AliyunConfig) : SimpleChannelInboundHandler() { // As we use inboundChannel.eventLoop() when building the Bootstrap this does not need to be volatile as // the outboundChannel will use the same EventLoop (and therefore Thread) as the inboundChannel. private var outboundChannel: Channel? = null override fun channelRead0(ctx: ChannelHandlerContext, msg: ByteBuf) { println("ProxyInboundHandler<<<" + msg.toString(CharsetUtil.UTF_8)) // val headers = msg.headers() // val headerMap = HashMap(headers.size()) // headers.forEach { headerMap[it.key] = it.value } // val outboundBody = Request(msg.method().name(), msg.uri(), msg.protocolVersion().text(), headerMap) // val outboundJson = JSON.toJSONString(outboundBody) val request = DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.POST, aliyunConfig.path) request.headers().set(HttpHeaderNames.HOST, aliyunConfig.host) request.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.CLOSE) request.headers().set(HttpHeaderNames.CONTENT_TYPE, HttpHeaderValues.APPLICATION_JSON) request.headers().set(HttpHeaderNames.CONTENT_LENGTH, msg.writerIndex()) // request.content().writeCharSequence(outboundJson, CharsetUtil.UTF_8) request.content().writeBytes(msg) // if (outboundChannel!!.isActive) { println("ProxyInboundHandler>>>${request.content().toString(CharsetUtil.UTF_8)}") outboundChannel!!.writeAndFlush(request).addListener(object : ChannelFutureListener { override fun operationComplete(future: ChannelFuture) { if (future.isSuccess) { // was able to flush out data, start to read the next chunk ctx.channel().read() } else { future.channel().close() } } }) } } override fun channelActive(ctx: ChannelHandlerContext) { val inboundChannel = ctx.channel() // Start the connection attempt. val outboundClient = Bootstrap() outboundClient.group(inboundChannel.eventLoop()) .channel(inboundChannel.javaClass) .handler(ProxyOutboundInitializer(inboundChannel)) .option(ChannelOption.AUTO_READ, false) val f = outboundClient.connect(aliyunConfig.host, aliyunConfig.port) outboundChannel = f.channel() f.addListener { future -> if (future.isSuccess) { // connection complete start to read first data inboundChannel.read() } else { // Close the connection if the connection attempt has failed. inboundChannel.close() } } } override fun channelInactive(ctx: ChannelHandlerContext) { if (outboundChannel != null) { closeOnFlush(outboundChannel!!) } } override fun exceptionCaught(ctx: ChannelHandlerContext, cause: Throwable) { cause.printStackTrace() closeOnFlush(ctx.channel()) } companion object { fun closeOnFlush(ch: Channel) { if (ch.isActive) { ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE) } } } } ``` ## Netty客户端Handle代码 ```kotlin package cn.wycode.lambda.proxy.outbound import cn.wycode.lambda.proxy.inbound.ProxyInboundHandler import io.netty.channel.* import io.netty.handler.codec.http.FullHttpResponse import io.netty.util.CharsetUtil class ProxyOutboundHandler(private val inboundChannel: Channel) : SimpleChannelInboundHandler() { override fun channelActive(ctx: ChannelHandlerContext) { println("ProxyOutBoundHandle==") ctx.read() } override fun channelRead0(ctx: ChannelHandlerContext, msg: FullHttpResponse) { println("ProxyOutBoundHandle<<<$msg") val body = msg.content().toString(CharsetUtil.UTF_8) println("ProxyOutBoundHandle body<<<$body") // val proxyResponse = try { // JSON.parseObject(body, Response::class.java) // } catch (e: Exception) { // e.printStackTrace() // msg.retain() // inboundChannel.writeAndFlush(msg).addListener(object : ChannelFutureListener { // override fun operationComplete(future: ChannelFuture) { // if (future.isSuccess) { // // was able to flush out data, start to read the next chunk // ctx.channel().read() // } else { // future.channel().close() // } // } // }) // return // } // val headers = CombinedHttpHeaders(true) // var outBytes:ByteArray? = null // if (proxyResponse.error == null) { // for (header in proxyResponse.headers!!) { // headers[header.key] = header.value // } // outBytes = Base64.getDecoder().decode(proxyResponse.content) // }else{ // outBytes = proxyResponse.error.toByteArray() // } // val response = DefaultFullHttpResponse(HttpVersion.HTTP_1_1, // HttpResponseStatus.valueOf(proxyResponse.code), // Unpooled.wrappedBuffer(outBytes), // headers, DefaultHttpHeaders()) msg.retain() inboundChannel.writeAndFlush(msg.content()).addListener(object : ChannelFutureListener { override fun operationComplete(future: ChannelFuture) { if (future.isSuccess) { // was able to flush out data, start to read the next chunk ctx.channel().read() } else { future.channel().close() } } }) } override fun channelInactive(ctx: ChannelHandlerContext) { println("ProxyOutBoundHandle!=") ProxyInboundHandler.closeOnFlush(inboundChannel) } override fun exceptionCaught(ctx: ChannelHandlerContext, cause: Throwable) { cause.printStackTrace() ProxyInboundHandler.closeOnFlush(ctx.channel()) } } ``` ## 云函数代码 ```java package cn.wycode.lambda; import com.aliyun.fc.runtime.Context; import com.aliyun.fc.runtime.FunctionComputeLogger; import com.aliyun.fc.runtime.StreamRequestHandler; import java.io.*; import java.net.Socket; import java.net.URL; import java.nio.charset.StandardCharsets; public class Lambda implements StreamRequestHandler { @Override public void handleRequest(InputStream input, OutputStream output, Context context) throws IOException { FunctionComputeLogger logger = context.getLogger(); StringBuilder sb = new StringBuilder(); byte[] buffer = new byte[1024]; int n; while ((n = input.read(buffer)) != -1) { sb.append(new String(buffer, 0, n, StandardCharsets.UTF_8)); } logger.info("handleRequest>>>" + sb.toString()); String firstLine = new BufferedReader(new StringReader(sb.toString())).readLine(); String host; int port; try { if (firstLine.startsWith("CONNECT ")) { String[] urlArray = firstLine.split(" ")[1].split(":"); host = urlArray[0]; port = Integer.parseInt(urlArray[1]); } else { URL url = new URL(firstLine.split(" ")[1]); host = url.getHost(); port = url.getPort(); if (port == -1) { if (url.getProtocol().equalsIgnoreCase("http")) { port = 80; } else if (url.getProtocol().equalsIgnoreCase("https")) { port = 443; } else { throw new IllegalArgumentException("端口无法解析"); } } } } catch (Exception e) { logger.error("url解析错误:" + e.getMessage()); return; } logger.info("host->" + host); logger.info("port->" + port); Socket s = new Socket(host, port); if (firstLine.startsWith("CONNECT ")) { String response = "HTTP/1.1 200 Connection Established"; output.write(response.getBytes(StandardCharsets.UTF_8)); output.flush(); sb.setLength(0); while ((n = input.read(buffer)) != -1) { sb.append(new String(buffer, 0, n, StandardCharsets.UTF_8)); } logger.info("handleRequest>>>" + sb.toString()); } OutputStream httpOutputStream = s.getOutputStream(); httpOutputStream.write(sb.toString().getBytes(StandardCharsets.UTF_8)); InputStream httpInputStream = s.getInputStream(); sb.setLength(0); while ((n = httpInputStream.read(buffer)) != -1) { output.write(buffer, 0, n); sb.append(new String(buffer, 0, n, StandardCharsets.UTF_8)); } httpInputStream.close(); httpOutputStream.close(); s.close(); input.close(); output.close(); logger.info("handleRequest<<<" + sb.toString()); } } ``` ## 遗留问题 - HTTP请求代理测试通过 - 可以在Netty客户端发送请求时，对请求体进行二进制加密，函数端解密；函数端收到真实响应加密，Netty客户端收到请求后解密。从而提高安全性 - 对于HTTP请求头为`Connection:keep-alive`的请求，函数端在读取真实响应时，会阻塞在流末尾的read方法而无法返回结果，`Connection:close`的请求正常 - HTTPS请求在有代理的情况下，浏览器会先发送一个HTTP CONNECT请求，以建立TSL通道。目前因为read阻塞问题还没有解决。附：本项目全部源码地址： Netty端：[https://github.com/wangyucode/lambda-cross-java](https://github.com/wangyucode/lambda-cross-java "github") 函数端：[https://github.com/wangyucode/aliyun-lambda](https://github.com/wangyucode/aliyun-lambda "github") 以上，转载请联系作者!

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