使用 http.request 在 node.js 中捕获 ECONNREFUSED？

Catching ECONNREFUSED in node.js with http.request?

提问by Cera

I'm trying to catch ECONNREFUSED errors when using a HTTP client in node.js. I'm making requests like this:

在 node.js 中使用 HTTP 客户端时，我试图捕获 ECONNREFUSED 错误。我正在提出这样的请求：

var http = require('http');
var options = { host: 'localhost', port: '3301', path: '/', method: 'GET' };

http.request(options).on('response', function (res) {
  // do some stuff
});

I can't figure out how to catch this error:

我不知道如何捕捉这个错误：

Error: connect ECONNREFUSED
  at errnoException (net.js:614:11)
  at Object.afterConnect [as oncomplete] (net.js:605:18)

If I do request.on('error', function () {});, it doesn't catch it. If I do it like this:

如果我这样做request.on('error', function () {});，它不会抓住它。如果我这样做：

var req = request.on(etc)
req.on('error', function blah () {});

Then I get TypeError: Object false has no method 'on'.

然后我得到TypeError: Object false has no method 'on'。

Do I really have to do a top-level uncaught error thing to deal with this? At the moment whatever I do my whole process quits out.

我真的必须做一个顶级未捕获的错误来处理这个问题吗？目前无论我做什么，我的整个过程都退出了。

Edit: I found some blog posts on how to do it by creating a connectionobject, calling requeston that, and then binding to errors on the connectionobject, but doesn't that make the entire http.request()shortcut useless?

编辑：我找到了一些关于如何通过创建connection对象，调用request它，然后绑定到connection对象上的错误来做到这一点的博客文章，但这不会使整个http.request()快捷方式无用吗？

回答by Ryan Olds

Any reason you're not using http://nodejs.org/docs/v0.6.5/api/http.html#http.requestas your base? Try this:

您不使用http://nodejs.org/docs/v0.6.5/api/http.html#http.request作为基础的任何原因？尝试这个：

var req = http.request(options, function(res) {
  // Bind 'data', 'end' events here
});

req.on('error', function(error) {
  // Error handling here
});

req.end();

回答by deezgz

Each call to http.request()returns its self. So try it like this...

每次调用都会http.request()返回其自身。所以试试这样...

http.request(options.function(){}).on('error',function(){}).end();

回答by VorpalSword

I've got a solution for this, having tried all the suggestions on this (and many other) pages.

我有一个解决方案，已经尝试了这个（和许多其他）页面上的所有建议。

My client needs to detect a turnkey product that runs embedded windows. The client is served from a different machine to the turnkey.

我的客户需要检测运行嵌入式窗口的交钥匙产品。客户从不同的机器到交钥匙服务。

The turnkey can be in 3 states:

交钥匙可以处于 3 种状态：

1. turned off
2. booted into windows, but not running the turnkey app
3. running the turnkey app

1. 关闭
2. 启动到 Windows，但没有运行交钥匙应用程序
3. 运行交钥匙应用

My client sends a 'find the turnkey product' GET message to my nodejs/express service, which then tries to find the turnkey product via http.request. The behavior for each of the 3 use cases are;

我的客户向我的 nodejs/express 服务发送“找到交钥匙产品”GET 消息，然后该服务尝试通过 http.request 找到交钥匙产品。3 个用例中的每一个的行为是；

1. timeout
2. ECONNREFUSED - because the windows embedded phase of the turnkey is refusing connections.
3. normal response to request (happy day scenario)

1. 暂停
2. ECONNREFUSED - 因为交钥匙的 windows 嵌入阶段拒绝连接。
3. 对请求的正常响应（快乐的一天场景）

The code below handles all 3 scenarios. The trick to catching the ECONNREFUSED event was learning that its handler binds to the socket event.

下面的代码处理所有 3 种情况。捕获 ECONNREFUSED 事件的技巧是了解其处理程序绑定到套接字事件。

var http = require('http');
var express = require('express');
var url = require('url');


function find (req, res) {
    var queryObj = url.parse(req.url, true).query;

    var options = {
        host: queryObj.ip, // client attaches ip address of turnkey to url.
        port: 1234,
        path: '/some/path',
    }; // http get options

    var badNews = function (e) {
        console.log (e.name + ' error: ', e.message);
        res.send({'ok': false, 'msg': e.message});
    }; // sends failure messages to log and client  

    // instantiate http request object and fire it
    var msg = http.request(options, function (response) {
        var body = '';

        response.on ('data', function(d) {
            body += d;
        }); // accumulate response chunks  

        response.on ('end', function () {
            res.send({'ok': true, 'msg': body});
            console.log('sent ok');
        }); // done receiving, send reply to client

        response.on('error', function (e) {
            badNews(e);
        }); // uh oh, send bad news to client   
    });

    msg.on('socket', function(socket) { 
        socket.setTimeout(2000, function () {   // set short timeout so discovery fails fast
            var e = new Error ('Timeout connecting to ' + queryObj.ip));
            e.name = 'Timeout';
            badNews(e);
            msg.abort();    // kill socket
        });
        socket.on('error', function (err) { // this catches ECONNREFUSED events
            badNews(err);
            msg.abort();    // kill socket
        });
    }); // handle connection events and errors

    msg.on('error', function (e) {  // happens when we abort
        console.log(e);
    });

    msg.end();
}