vscode-debug-proxy.js

// 
// THIS IS NO LONGER NECESSARY, VSCODE CAN DO REMOTE DEBUGGING NOW..
//
// Published @ http://code.xpotent.com/2015/12/debugging-nodejs-within-docker.html
//
// VSCode requests a PID at the onset of a debugging session and monitors the process
// to detect when it is no longer running. For some reason, VSCode does not rely on socket
// state to determine this. VSCode monitors the pid and will exit if it isn't active.
// 
// This proxy detects the pid within one of the initial debug messages from a node instance
// on a remote server, then changes it to the local pid of this debug-proxy process. 
//
// example request: 
//     {"command":"evaluate","arguments":{"expression":"process.pid","global":true},"type":"request","seq":1}
//
// example response: 
//     {"seq":59,"request_seq":1,"type":"response","command":"evaluate","success":true,"body":
//                 {"handle":0,"type":"number","value":<PID>,"text":"<PID>"},"refs":[],"running":true} 
//
// Node must be started using the --debug flag, and preferably the --nolazy flag too.
//
//   node  --debug  --nolazy  app.js  
//   node  --debug-brk  --nolazy  app.js  
//   node  --debug=5858  --nolazy  app.js  
//
// Note that VSCode also emits absolute path to the remote node debugger; therefore, it is 
// necessary to mount the source folder to the same location within the file system as the 
// server's. Within OSX, this can be done using bind and osxfuse. Bind will need to be 
// downloaded and built, while osxfuse can be installed.
//
//   $ sudo mkdir /server-app
//   $ sudo bindfs $(pwd)/local-source /server-app
//
//   $ node debug-proxy 5860 5858
//
// VERSION
//    
//   2015-11-30 Dan Abraham - Initial release.
//   2015-12-04 Dan Abraham - Bug fixes, during initialization.
//

var net = require("net");
var spawn = require("child_process").spawn;

if (process.argv.length < 4) {
    console.log("\r\n\r\n    usage: node debug-proxy.js <local-port> <remote-port>\r\n\r\n");
    process.exit(1);
}

var localHost = "127.0.0.1";
var nodeAppName = process.argv[0];
var localClientPort = parseInt(process.argv[2]);
var remoteProcessPort = parseInt(process.argv[3]);
var outputPackets = (process.argv[4]);

console.log("");
console.log("Local Port:       ", localClientPort);
console.log("Remote Port:      ", remoteProcessPort);
console.log("");

var remoteProcessSocket = null;
var localEditorSocket = null;
var localChildProcess = null;

var transactionNumber = 0;
var transactionNumberPid = -1;
var transactionTriggerPid = '{"expression":"process.pid","global":true}';

process.on("SIGTERM", function (code) {
    console.log("debugger-proxy: terminated (SIGTERM) (code: " + code + ")");
    localEditorShutdown();        
    remoteProcessDetach();
});

process.once("uncaughtException", function (error) {
    console.log("debugger-proxy: fatal error, shutdown initiated");
    console.log(error.stack);      
    localEditorShutdown();
    remoteProcessDetach();
    process.exit();        
});

function remoteProcessDetach() { 
    if (remoteProcessSocket) {
        console.log("debugger-proxy: executed remoteProcessDetach");    
        remoteProcessSocket.end();
        remoteProcessSocket.unref();        
        remoteProcessSocket = null;    
    }
}

// Attaching to remote node process
function remoteProcessAttach() {
    console.log("debugger-proxy: attempting remoteProcessAttach"); 

    if (remoteProcessSocket == null) {
        remoteProcessSocket = new net.Socket();
        remoteProcessSocket.on("data", function (data) { 
            var outString = data.toString();
            if (outputPackets) {
                console.log("\r\n------------------- RESPONSE (trans: " + transactionNumber + ")\r\n");
                console.log(outString);      
            }
            // Confirming it's a JSON payload, PID is expected to be a small and complete response (1 packet)
            var jsonDelimiterIndex = outString.indexOf('{');
            if ((transactionNumberPid === transactionNumber) && (jsonDelimiterIndex > 0) && 
                (outString.indexOf('type":"response","command":"evaluate","success":true') > 0)) {
                var outObject = JSON.parse(outString.substr(jsonDelimiterIndex));
                var originalPid = outObject.body.value;
                outObject.body.value = process.pid;
                outObject.body.text =  process.pid.toString();
                var outStringNew = JSON.stringify(outObject);
                var outPacketNew = "Content-Length: " + (outStringNew.length) + "\r\n\r\n" + outStringNew;
                localEditorSocket.write(new Buffer(outPacketNew));                 
                console.log("\r\nPID Adjustment From (" + originalPid + ") To (" + outObject.body.value + ")\r\n");
                console.log(outPacketNew);      
            } else {
                if (localEditorSocket != null) {
                    localEditorSocket.write(data);
                }
            }
        });
        remoteProcessSocket.on("close", function () {
            console.log("debugger-proxy: remoteProcessSocket closed");   
            remoteProcessSocket.unref();                       
            remoteProcessSocket = null;
        });
        remoteProcessSocket.on("connect", function () {
            console.log("debugger-proxy: remoteProcessSocket connected");
        });        
        remoteProcessSocket.on("error", function (err) {
            console.log("debugger-proxy: remoteProcessSocket error");
            console.log(err);            
            remoteProcessSocket.unref();               
        });           
        remoteProcessSocket.connect(remoteProcessPort, localHost, function () {
            console.log("debugger-proxy: remoteProcessSocket created (" + localHost + ":" + remoteProcessPort + ")");
        });
    }
    return; 
}

// Start socket server listening for local connection from editor
var localServer = net.createServer(function (socket) {    
    
    // Service only handles one editor connection at a time
    if (localEditorSocket != null) {
        console.log("debugger-proxy: localEditorSocket connection rejected - already connected");
        return;
    }
    
    console.log("");
    console.log("debugger-proxy: localEditorSocket connected, attaching to remoteProcessSocket");
    if (!remoteProcessSocket) remoteProcessAttach();        

    // Wire up local socket server 
    transactionNumber = 0;
    localEditorSocket = socket;
    localEditorSocket.on("data", function (data) {
        transactionNumber++;
        var inString = data.toString();
        if (outputPackets) {
            console.log("\r\n------------------- REQUEST (trans: " + transactionNumber + ")\r\n");             
            console.log(inString);    
        }
        // Flagging VSCode PID requests, so the can be changed on the inbound trip
        if (inString.indexOf(transactionTriggerPid) > 0)
            transactionNumberPid = transactionNumber;  
            
        if (remoteProcessSocket != null) {
            remoteProcessSocket.write(data);                
        } else {        
            console.log("debugger-proxy: error connecting to remote process debugger");    
        }   
    });
    localEditorSocket.on("close", function (data) {
        console.log("debugger-proxy: localEditorSocket disconnected (trans: " + transactionNumber + ")");
        localEditorSocket = null;
    });
});

function localEditorListen() {
    localServer.listen(localClientPort, localHost);
    console.log("debugger-proxy: localEditorSocket listening for connection (" + localHost + ":" + localClientPort + ")");        
}

function localEditorShutdown(restart) {
    console.log("debugger-proxy: executed localServer shutdown");
    localServer.close();
    localServer.unref();    
    localEditorSocket = null;
    
    if (restart) {
        setTimeout(function() {
            localEditorListen();
        }, 5000)
    }
}

localEditorListen();