javascript – node.js和express：如何等待udp响应

我在这里学习一点node.js编程并遇到了问题.

当express获取POST请求时,它应该使用dgram模块通过UDP进行radius验证. Radius身份验证的响应稍后会出现,但POST请求回调已经退出,req和res变量将丢失,并且无法使用相同的TCP连接进行响应.

如果我应该等待半径响应(这是非常快)我应该如何在node.js&中等待表达 ？

下面的代码执行基本的POST处理和radius验证.

非常感谢您的任何提示.

    var http = require('http');
    var express = require('express');
    var bodyParser = require('body-parser');
    var radius = require('radius');
    var dgram = require('dgram');

    var radius_secret = 'really_secret';
    var radius_server = '127.0.0.1';
    var radius_port = '1812';

    function handleAuthentication(req, res) {
        console.log("BODY:",req.body);
        var client = dgram.createSocket("udp4");
        var account = req.body.account; 
        var password = req.body.password;
        var packet = {
            code: 'Access-Request',
            secret: radius_secret,
            identifier: 0,
            attributes: [
                ['NAS-IP-Address', radius_server],
                ['User-Name', account + "@exampledomain.something"],
                ['User-Password', password]
            ]
        };

        client.on('error', function(e) {
                throw e;
            });

        client.on('message', function(msg, rinfo) {
            var radius_response = radius.decode({packet: msg, secret: radius_secret});
            console.log(radius_response);
        });

        var encoded = radius.encode(packet);
        client.send(encoded, 0, encoded.length, radius_port, radius_server);
    }

    var app = express();
    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({ extended: false}));

    app.post('/authenticate', function(req, res) {
        // Authenticate against radius server
        handleAuthentication(req, res);

        // The radius response is not received yet, and we will exit the post request
        // here and loose the req and res. 
    });

    var server = http.createServer(app);
    server.listen(80);

解决方法:

您需要在客户端回调中进行响应.因此,例如,在消息后回复：

client.on('message', function(msg, rinfo) {
     var radius_response = radius.decode({packet: msg, secret: radius_secret});
     console.log(radius_response);
     res.send('somethingCalculatedWithUDPResponse');
 });

你应该在错误回调中类似地处理它.

当函数结束时,res和req不会“死”,它们仍然可以被作为回调传递的闭包引用.