如何使用 xterm.js 向 AWS 会话管理器 websocket url 发送命令？

Question

我有一个由 AWS 创建的 websocket url。 URL 由 aws ssm start session 使用 .net sdk 创建。启动会话方法为我提供了 streamUrl、令牌和会话 ID。 URL 格式如下：

wss://ssmmessages.ap-south-1.amazonaws.com/v1/data-channel/sessionidhere?role=publish_subscribe

在 placeof“sessionidhere”处有我无法共享的实际会话 ID。

我想使用 xterm.js 在网络上打开终端。我读到 xterm.js 可以连接到 websocket URL、发送消息和接收输出。

我的 javascript 代码在这里 :

<!doctype html>
<html>
<head>
    <link href="~/xterm.css" rel="stylesheet" />
    <script src="~/Scripts/jquery-3.4.1.js"></script>
    <script src="~/Scripts/bootstrap.js"></script>
    <script src="~/xterm.js"></script>
</head>
<body>
    <div id="terminal"></div>
    <script type="text/javascript">
        var term = new Terminal({
            cursorBlink: "block"
        });
        var curr_line = "";
        var entries = [];
        term.open(document.getElementById('terminal'));    
        const ws = new WebSocket("wss://ssmmessages.ap-south-1.amazonaws.com/v1/data-channel/sessionid?role=publish_subscribe?token=tokenvalue");
        var curr_line = "";
        var entries = [];
      
        term.write("web shell $ ");

        term.prompt = () => {
            if (curr_line) {
                let data = {
                    method: "command", command: curr_line
                }
                ws.send(JSON.stringify(data));
            }
        };
        term.prompt();
        ws.onopen = function (e) {
            alert("[open] Connection established");
            alert("Sending to server");         
            var enc = new TextEncoder("utf-8"); // always utf-8
            // console.log(enc.encode("This is a string converted to a Uint8Array"));
            var data = "ls";
            console.log(enc.encode(data));
            alert(enc.encode(data));
            ws.send(enc.encode(data));
            alert(JSON.stringify(e));
        };
        ws.onclose = function (event) {
            if (event.wasClean) {
                alert(`[close] Connection closed cleanly, code=${event.code} reason=${event.reason}`);
            } else {
                // e.g. server process killed or network down
                // event.code is usually 1006 in this case
                alert('[close] Connection died');
            }
        };

        ws.onerror = function (error) {
            alert(`[error] ${error.message}`);
        };

        // Receive data from socket
        ws.onmessage = msg => {
            alert(data);
            term.write("\r\n" + JSON.parse(msg.data).data);
            curr_line = "";
        };

        term.on("key", function (key, ev) {
            //Enter
            if (ev.keyCode === 13) {
                if (curr_line) {
                    entries.push(curr_line);
                    term.write("\r\n");
                    term.prompt();
                }
            } else if (ev.keyCode === 8) {
                // Backspace
                if (curr_line) {
                    curr_line = curr_line.slice(0, curr_line.length - 1);
                    term.write("\b \b");
                }
            } else {
                curr_line += key;
                term.write(key);
            }
        });

        // paste value
        term.on("paste", function (data) {
            curr_line += data;
            term.write(data);
        });
    </script>
</body>
</html>

现在，正在打开会话，我收到已建立连接的警报。连接成功，但每当我尝试发送命令时，连接都会通过 'request to open data channel does not contain a token' 关闭。我试过用 3 种方式发送命令。

首先是：

ws.send("ls")

第二个：

let data = {
    method: "command", command: curr_line
}
ws.send(JSON.stringify(data));

但面临同样的错误，即打开数据通道的请求不包含令牌，连接中断

第三名：

var enc = new TextEncoder("utf-8"); 
var data = "ls";           
ws.send(enc.encode(data));

第三，我没有收到任何错误，但也没有得到输出...有人可以帮忙吗？

Answer 1

AWS 会话管理器使用的协议包括以下内容：

在流上打开一个 websocket 连接 URL
发送由以下JSON字符串组成的身份验证请求：

{
  "MessageSchemaVersion": "1.0",
  "RequestId": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "TokenValue": "<YOUR-TOKEN-VALUE>"
}

从这一刻起，协议不再 JSON。它在官方 Amazon SSM agent which is required if you want start a SSM session from the AWS CLI. The payload must be sent & receive according this binary format

中实现

几个月前我的要求与您完全相同，所以我制作了一个 AWS 会话管理器客户端库：https://github.com/bertrandmartel/aws-ssm-session for nodejs and browser. If you want more information about how the protocol works, checkout this

可供浏览器使用的示例代码xterm.js

首先克隆项目并使用 aws-api 和一些实用脚本生成 websocket URL 和令牌：

git clone git@github.com:bertrandmartel/aws-ssm-session.git
cd aws-ssm-session
npm i
npm run build
node scripts/generate-session.js

这给你：

{
  SessionId: 'xxxxxx-xxxxxxxxxxxxxx',
  TokenValue: 'YOUR_TOKEN',
  StreamUrl: 'wss://ssmmessages.eu-west-3.amazonaws.com/v1/data-channel/user-xxxxxxxxxxxxxx?role=publish_subscribe'
}

然后提供示例应用程序：

npm install http-server -g
http-server -a localhost -p 3000

转到 http://localhost:3000/test/web，输入 websocket URI 和令牌：

sample code for browser :

import { ssm } from "ssm-session";

var socket;
var terminal;

const termOptions = {
  rows: 34,
  cols: 197
};

function startSession(){
  var tokenValue = document.getElementById("tokenValue").value;
  var websocketStreamURL = document.getElementById("websocketStreamURL").value;
  
  socket = new WebSocket(websocketStreamURL);
  socket.binaryType = "arraybuffer";
  initTerminal()

  socket.addEventListener('open', function (event) {
    ssm.init(socket, {
      token: tokenValue,
      termOptions: termOptions
    });
  });
  socket.addEventListener('close', function (event) {
    console.log("Websocket closed")
  });
  socket.addEventListener('message', function (event) {
    var agentMessage = ssm.decode(event.data);
    //console.log(agentMessage);
    ssm.sendACK(socket, agentMessage);
    if (agentMessage.payloadType === 1){
      terminal.write(agentMessage.payload)
    } else if (agentMessage.payloadType === 17){
      ssm.sendInitMessage(socket, termOptions);
    }
  });
}

function stopSession(){
  if (socket){
    socket.close();
  }
  terminal.dispose()
}

function initTerminal() {
  terminal = new window.Terminal(termOptions);
  terminal.open(document.getElementById('terminal'));
  terminal.onKey(e => {
    ssm.sendText(socket, e.key);
  });
  terminal.on('paste', function(data) {
    ssm.sendText(socket, data);
  });
}

如何使用 xterm.js 向 AWS 会话管理器 websocket url 发送命令？

how to send commands to AWS Session manager websocket url using xterm.js?

javascript

amazon-web-services

websocket

xtermjs

aws-ssm