无法在 node.js 中建立对等 webrtc 连接答案

【问题标题】：Cannot establish peer to peer webrtc connection in node.js无法在 node.js 中建立对等 webrtc 连接
【发布时间】：2022-01-18 21:04:01
【问题描述】：

我正在使用一个名为 wrtc 的 WebRTC npm 包和 node.js 的内置网络库。由于某种原因，我无法建立连接。我得到了错误：

C:\dev\WebRTCchat\node_modules\wrtc\lib\index.js:49
  this._send(data);
       ^
DOMException [InvalidStateError]: RTCDataChannel.readyState is not 'open
'
    at RTCDataChannel.send (C:\dev\WebRTCchat\node_modules\wrtc\lib\inde
x.js:49:8)
    at C:\dev\WebRTCchat\clientA.js:35:35

有什么想法吗？所以这里是客户 A 代码（谁创建了报价）

clientA.js

const net = require('net');
const { RTCPeerConnection } = require("wrtc");

const connA = new RTCPeerConnection();
connA.onicecandidate = () => console.log("Ice candidate added. ");// + JSON.stringify(connA.localDescription));
const dc = connA.createDataChannel("channel");
dc.onmessage = e => console.log("Message -> " + e.data);
dc.onopen = () => console.log("Client connected!");

function delay(ms) {
    return new Promise(res => setTimeout(res, ms));
}

function createSDPOffer() {
    return new Promise(resolve => connA.createOffer()
        .then(o => {
            connA.setLocalDescription(o);
            console.log("Local Description set!");
            resolve(o);
        }));
}

function getSDPAnswer(answer) {
    connA.setRemoteDescription(answer).then(a => console.log("Remote description set!"));
}

const server = net.createServer();
server.on('connection', socket => {
    createSDPOffer().then(offer => {
        socket.write(JSON.stringify(offer));
    })

    socket.on('data', data => {
        getSDPAnswer(JSON.parse(data));
        delay(1000).then(() => dc.send("Hello I am client A"));
    })
})

server.listen(1337, '127.0.0.1');

然后是客户 B（收到报价并创建答案的人）

clientB.js

const net = require('net');
const { RTCPeerConnection } = require("wrtc");

const connB = new RTCPeerConnection();
const socket = new net.Socket();

function delay(ms) {
    return new Promise(res => setTimeout(res, ms));
}

socket.connect(1337, "127.0.0.1");

socket.on('data', (data) => {
    getSDPOffer(JSON.parse(data));

    sendSDPAnswer().then(a => socket.write(JSON.stringify(a)));

    delay(2000).then(() => {
        connB.dc.send("Hello I am B")
    });

});

socket.on('close', () => {

})


function getSDPOffer(offer) {
    connB.onicecandidate = () => console.log("Ice candidate added. "); //+ JSON.stringify(connB.localDescription));

    connB.ondatachannel = e => {
        connB.dc = e.channel;
        connB.dc.onopen = () => console.log("Client connected!");
        connB.dc.onmessage = e => console.log("Message -> " + e.data);
    }

    connB.setRemoteDescription(offer)
        .then(() => console.log("Remote Description Offer set!"));
}

function sendSDPAnswer() {
    return new Promise(resolve => {
        connB.createAnswer()
            .then(a => {
                connB.setLocalDescription(a);
                console.log("Local Description set!");
                resolve(a);
            });
    })
}

【问题讨论】：

ice候补需要在远端交换和添加，而不是登录。
您能否提供更多关于如何做到这一点的信息？

标签： node.js sockets webrtc

【解决方案1】：

我发现使用 connA.localDescription 而不是 createOffer 创建的 offer 对象，一切正常。不过不知道为什么..

function createSDPOffer() {
    return connA.createOffer()
        .then(o => {
            connA.setLocalDescription(o);
            console.log("Local Description set!");
        });
}

...

const server = net.createServer();
server.on('connection', socket => {
    createSDPOffer().then(() => {
        socket.write(JSON.stringify(connA.localDescription));
    })

【讨论】：