节点 JS 套接字，本地主机工作，127.0.0.1 不工作

Question

由于某种原因，localhost:3000 能够在我的服务器上创建一个套接字，但 127.0.0.1:3000 不能。 127.0.0.1:3000 成功拉取内容但未连接到服务器，尽管代码如下：

app.use(function (req, res, next) {

    // Website you wish to allow to connect
    res.setHeader('Access-Control-Allow-Origin', 'http://localhost:3000');
    res.setHeader('Access-Control-Allow-Origin', 'http://127.0.0.1:3000');

    // Request methods you wish to allow
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');

    // Request headers you wish to allow
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');

    // Set to true if you need the website to include cookies in the requests sent
    // to the API (e.g. in case you use sessions)
    res.setHeader('Access-Control-Allow-Credentials', true);

    // Pass to next layer of middleware
    next();
});

这是我得到的错误：

Access to XMLHttpRequest at 'http://localhost:3000/socket.io/?EIO=4&transport=polling&t=NvqFfaS' 
from origin 'http://127.0.0.1:3000' has been blocked by CORS policy:
No 'Access-Control-Allow-Origin' header is present on the requested resource. 

我不明白为什么它对待 2 的方式不同。

这是运行的 server.js 文件：

var express = require('express');

var app = express(); 
var server = app.listen(3000);

app.use(express.static('public'));



app.use(function (req, res, next) {

    // Website you wish to allow to connect
    res.setHeader('Access-Control-Allow-Origin', 'http://localhost:3000');
    res.setHeader('Access-Control-Allow-Origin', 'http://127.0.0.1:3000');

    // Request methods you wish to allow
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');

    // Request headers you wish to allow
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');

    // Set to true if you need the website to include cookies in the requests sent
    // to the API (e.g. in case you use sessions)
    res.setHeader('Access-Control-Allow-Credentials', true);

    // Pass to next layer of middleware
    next();
});









console.log("Socket is running"); 

var socket = require('socket.io');

var io = socket(server);
io.sockets.on('connection',newConnection); 
function newConnection(socket){
    console.log('new connection: '+socket.id);
    socket.on('mouse',mouseMsg);

    function mouseMsg(data){
        socket.broadcast.emit('mouse',data);
        //io.sockets.emit('mouse',data);
        console.log(data);
    }

}

Answer 1

IIRC，您不能有多个 Access-Control-Allow-Origin 标头。这是我使用的：

const headers = {
    'Content-Type': contentType,
    ...(req.headers.origin ? {'Access-Control-Allow-Origin': '"' + req.headers.origin + '" always'} : {}),
    'Access-Control-Allow-Credentials': '"true"',
    'Access-Control-Allow-Headers': '"origin,range,hdntl,hdnts,accept-encoding,referer,CMCD-req,CMCD-Object,CMCD-Status,CMCD-Session" always',
    'Access-Control-Allow-Methods': '"GET,POST,OPTIONS" always',
    'Access-Control-Expose-Headers': '"Server,range,Date,hdntl,hdnts,Akamai-Mon-Iucid-Ing,Akamai-Mon-Iucid-Del,Akamai-req-BC,Content-Length,Content-Range,Geo-Info,Quic-Version" always',
    'Cache-Control': 'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0',
}

我不明白为什么它对待 2 的方式不同。

我刚刚做了一个实验：我清空了/etc/hosts，然后我放了

1.1.1.1 localhost

进入/etc/hosts，然后ping localhost说：

64 bytes from localhost (1.1.1.1): icmp_seq=1 ttl=59 time=31.2 ms

因此，由于某些未知原因，localhost 不一定是127.0.0.1。