Develop Reference

i want to send a CTRL + C command to client how can i acheive this in NodeJS?

My Code Looks Like this
var Client = require('ssh2').Client;
var fs=require('fs');
var conn = new Client();
conn.on('ready', function() {
console.log('Client :: ready');
conn.shell('xtail', function(err, stream) {
stream.write('xtail\n\r');
if (err) throw err;
stream.on('close', function(code, signal) {
console.log('Stream :: close :: code: ' + code + ', signal: ' + signal);
conn.end();
}).on('data', function(data) {
// stream.stdin.write('?');
console.log('hey');
console.log('STDOUT: ' + data);
fs.appendFile('D:\\Breme\\As1.txt',data,function(err){
if(err)
{
console.log(err);
}
//console.log('file saving..')
});
// setTimeout(function(){
// process.exit(1);
// }, 20000);
}).stderr.on('data', function(data) {
console.log('STDERR: ' + data);
conn.destroy();
});
});
}).connect({
host: '10.214.14.15',
port: 22,
username: 'bwadn',
password: 'bwain'
});
after connecting to server I am downloading the file but I want to send 'Ctrl+C' command from client, so that it stops receiving data
Can anyone please help me in solving this, As i am new to NodeJS I need your support in solving this...thanks

Most reliable way in this particular case, since you are using a variant of tail in your shell, is to use
stream.write('\x03'); //send ctrl+c
you would need to send it when you know you don't need xtail output anymore. It is beyond the scope of this question to discuss the means, but setTimeout is definitely not a good idea.
Alternative (preferred) method:
stream.signal('INT')
and for other uses see Ssh2 Channel API

node js :Can\'t set headers after they are sent

How to send the response properly. I like to move to another page after FTP and Telnet sessions.
Even tried using res.redirect function too. While using res.redirect, i commented window.location= "SaveRedirect"; line, in javascript of html page. Even then, I get the same error.
Here presenting the code snippet,
the javascript code in html
IPData ={
"DeviceIpAddr": "192.168.1.2"
};
function processSave() {
$.post("PostSave", IPData, function(data) {
window.location= "SaveRedirect";
});
return true;
}
node js code snippet
app.get('/SaveRedirect', function (req, res) {
res.sendFile( __dirname + "/" + "Page2.htm" );
})
var bodyParser = require('body-parser');
var testJsonEncoder = bodyParser.json();
urlEncoded = bodyParser.urlencoded({ extended: true });
app.post('/PostSave', testJsonEncoder,urlEncoded, function(request, response){
var LoginData = JSON.stringify(request.body, null, 4);
console.log(LoginData);
FormDataObj = JSON.parse(LoginData);
gDeviceIpAddress = FormDataObj.DeviceIpAddr;
console.log("IP Address" + gDeviceIpAddress);
console.log("FTP to linux box...");
ftpFile(gDeviceIpAddress, "PUT", "temp_data.json", response);
console.log("FTP temp_data file to linux box... Done!");
TelnetLinux(gDeviceIpAddress);
console.log("Telnet to linux box... Done!");
response.send("just to send response");
//response.json(LoginData);
});
function ftpFile(ftpIPAddr, operation, filename, resp) {
console.log("ftpIPAddr = " + ftpIPAddr);
ftpConfig.host = ftpIPAddr;
// Handle error
ftpClient.on("error", function (err) {
console.log(" - ERROR HANDLE - \n");
console.log(err);
resp.send("FAIL: " + err.message);
ftpClient.end();
});
// Handle error
ftpClient.on("ready", function () {
console.log("Connected....\n");
if(operation == "GET") {
console.log("filename : " + filename);
ftpClient.get(filename, function(err, stream) {
if (err)
{
resp.send("FAIL: " + err.message + " - " + filename);
ftpClient.end();
//throw err;
}
else {
stream.once('close', function() { ftpClient.end(); });
stream.pipe(fs.createWriteStream('test_data.json'));
resp.send("SUCCESS: file received");
ftpClient.end();
}
});
}
if(operation == "PUT") {
ftpClient.put(filename, filename, function(err) {
if (err) {
resp.send("FAIL: " + err.message + " - " + filename);
ftpclient.end();
throw err;
}
else {
resp.send("SUCCESS: file sent");
ftpClient.end();
}
});
}
});
ftpClient.connect(ftpConfig);
}
function TelnetLinux(deviceIPAddr) {
var telnetParams = {
host: deviceIPAddr,
port: 23,
username: "webtest",
password: "test123",
shellPrompt: '$',
timeout: 1500,
// removeEcho: 4
};
cmd = "ls";
console.log("Telnet Address : " + deviceIPAddr);
telnetClient.on('ready', function(prompt) {
telnetClient.exec(cmd, function(err, response) {
//console.log(response);
console.log("Cmd executed !");
});
});
telnetClient.on('timeout', function() {
console.log('telnet socket timeout!')
telnetClient.end();
});
telnetClient.on('close', function() {
console.log('telnet connection closed');
});
telnetClient.connect(telnetParams);
}
Error :
c:\WebTest>node webapp.js
Example app listening at http://:::8081
IP Address192.168.1.2
FTP to linux box...
ftpIPAddr = 192.168.1.2
FTP temp_data file to linux box... Done!
Telnet Address : 192.168.1.2
Telnet to linux box... Done!
Cmd executed !
telnet socket timeout!
telnet connection closed
Connected....
_http_outgoing.js:346
throw new Error('Can\'t set headers after they are sent.');
^
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:346:11)
at ServerResponse.header (c:\WebTest\node_modules\express\lib\response.js:719:10)
at ServerResponse.send (c:\WebTest\node_modules\express\lib\response.js:164:12)
at c:\WebTest\webapp.js:222:11
at Object.cb (c:\WebTest\node_modules\ftp\lib\connection.js:1017:13)
at Parser.<anonymous> (c:\WebTest\node_modules\ftp\lib\connection.js:117:20)
at emitTwo (events.js:100:13)
at Parser.emit (events.js:185:7)
at Parser._write (c:\WebTest\node_modules\ftp\lib\parser.js:59:10)
at doWrite (_stream_writable.js:301:12)
at writeOrBuffer (_stream_writable.js:287:5)
at Parser.Writable.write (_stream_writable.js:215:11)
at Socket.ondata (c:\WebTest\node_modules\ftp\lib\connection.js:273:20)
at emitOne (events.js:90:13)
at Socket.emit (events.js:182:7)
at readableAddChunk (_stream_readable.js:153:18)

This happens when you try to do res.send (or response.send) multiple times in the same call. I believe it has to do with this bit of code:
app.post('/PostSave', testJsonEncoder, urlEncoded, function(request, response) {
var LoginData = JSON.stringify(request.body, null, 4);
console.log(LoginData);
FormDataObj = JSON.parse(LoginData);
gDeviceIpAddress = FormDataObj.DeviceIpAddr;
console.log("IP Address" + gDeviceIpAddress);
console.log("FTP to linux box...");
ftpFile(gDeviceIpAddress, "PUT", "temp_data.json", response);
console.log("FTP temp_data file to linux box... Done!");
TelnetLinux(gDeviceIpAddress);
console.log("Telnet to linux box... Done!");
response.send("just to send response");
//response.json(LoginData);
});
You're doing a response.send at the end of this function, and again in ftpFile()

Since you are sending response multiple times in app.post("/Postsave" and function ftpFile for the same request, you get this error.
To resolve this, I would suggest you to send the result(or error) from the ftpfile back to the app.post(i.e., through callback) and then based on the result or error send the response from the app.post function.

display ssh2 stdout and stderr in textarea

I'm building a node.js application to manage servers.
In this application, I can create some shell scripts and execute them on a server by clicking on a button.
Here is what I have in my routes.js file for this action :
app.get('/exec', isLoggedIn, function(req, res) {
var url = require('url');
var url_parts = url.parse(req.url, true);
var query = url_parts.query;
var Server = require('../app/models/server');
var Script = require('../app/models/script');
var async = require('async');
var scriptId = query.scriptId;
var userId = query.userId;
var serverId = query.serverId;
var stdout = "";
var stderr = "";
async.parallel({
servers: function(callback){
Server.find({"_id" : serverId}).exec(callback);
},
scripts: function(callback){
Script.find({"_id" : scriptId}).exec(callback);
}
}, function(err, results) {
if (err)
res.send(err);
var selectedServer = results.servers;
var selectedScript = results.scripts;
var serverIp = selectedServer[0].serverDetails.serverAddress;
var serverPort = selectedServer[0].serverDetails.serverPort;
var serverUsername = selectedServer[0].serverDetails.serverUsername;
var scriptContent = selectedScript[0].scriptDetails.scriptContent;
var Connection = require('ssh2');
var conn = new Connection();
conn.on('ready', function() {
//console.log('Connection :: ready');
conn.exec(scriptContent, function(err, stream) {
if (err) throw err;
stream.on('exit', function(code, signal) {
//console.log('Stream :: exit :: code: ' + code + ', signal: ' + signal);
}).on('close', function() {
//console.log('Stream :: close');
conn.end();
}).on('data', function(data_out) {
console.log('STDOUT: \n' + data_out);
stdout = stdout + data_out;
res.render('execresults.ejs', {
stdout : stdout
});
}).stderr.on('data', function(data_err) {
console.log('STDERR: \n' + data_err);
});
});
}).connect({
host: serverIp,
port: serverPort,
username: serverUsername,
privateKey: require('fs').readFileSync('id_rsa')
});
conn.on('error', function(e) { console.log("Connection failed or timed out")});
});
});
It works fine and I have the results of the execution in the console. But I would like to display both stdout and stderr results in two textarea of an ejs page.
The problem is that when I run a simple command like "uptime", it works, I will have the stdout result displayed in my textarea.
But when the shell script returns both stdout and stderr, or if stdout is a large amount of text, I don't have everything passed to my ejs page because of this error I think : Error: Can't set headers after they are sent.
My question is : How can I send both stdout and stderr to my ejs page, only when the script is completely executed ? I tried to build a "stdout" variable by concatenating all stdout output but it doesn't seem to work...
Can someone help me ?
thanks a lot

Assuming the process eventually ends on its own and it does not output a lot of data, you could probably just buffer the data and then render when the process closes:
conn.exec(scriptContent, function(err, stream) {
if (err)
return res.send(err);
var stdout = '',
stderr = '';
stream.on('close', function() {
conn.end();
res.render('execresults.ejs', {
stdout: stdout,
stderr: stderr
});
}).on('data', function(data) {
stdout += data;
}).stderr.on('data', function(data) {
stderr += data;
});
});
Secondly,
if (err)
res.send(err);
should really have a return:
if (err)
return res.send(err);
to prevent further execution on errors.

How to capture database connection state or ping connection?

Using MySql driver for Node.js, here is my ping method:
function ping(){
connection.connect(function(err) {
if (err) {
console.error('error connecting: ' + err.stack);
return false;
}
console.log('connection authenticated: ' + (connection.state == "authenticated"));
console.log('connected as id ' + connection.threadId);
});
console.log("connection: " + connection.state);
return (connection.state == "authenticated");
}
Apparently, this node-mysql library does not have a native Ping method. I thought this would serve well in its stead. However, I am seeing the following issue in the console:
debugger listening on port 53213
connection: disconnected
Fri, 26 Dec
2014 14:12:38 GMT RazorJS Express server listening on port 3000
connection authenticated: true
connected as id 17
It seems that the connection state is being logged and returning false before the connection is actually open. Maybe this is being executed async? How can I get this to function synchronously?

You have written the below outside the callback on connection.connect function.So before your connection.connect executes its callback ,the below code gets executed(async nature of node.js) and therefore its first consoled as disconnected.
console.log("connection: " + connection.state);
return (connection.state == "authenticated");
The above should be inside the callback.
function ping() {
connection.connect(function(err) {
if (err) {
console.error('error connecting: ' + err.stack);
return false;
}
console.log('connection authenticated: ' + (connection.state == "authenticated"));
console.log('connected as id ' + connection.threadId);
console.log("connection: " + connection.state);
return (connection.state == "authenticated");
});
}

nodejs Error: Parse Error at Socket.ondata

I have got some error when use http.request to make a client request(node v0.6.18, v0.6.3), the following code produces the error and I have some questions.
var http = require('http');
var url = require('url');
http.createServer(function(req, res) {
var data = '多情自古空余恨';
res.writeHead(200, {
'Content-Type': 'text/plain',
'Content-Length': 1 //ERROR
});
res.end(data);
}).listen(3000);
function request(options, callback) {
var req = http.request(options, function(res) {
var data = '';
res.setEncoding = 'utf8';
res.on('data', function(chunk) {
data += chunk;
});
res.on('error', function(err) {
callback(new Error('res error: ' + err));
});
res.on('end', function() {
console.log('res on end');
callback(null, data);
});
});
req.on('socket', function(socket) {
socket.on('error', function(err) {
console.log('socket on error');
callback('socket error: ' + err);
req.abort();
});
});
req.end();
}
request({
host: 'localhost',
port: 3000,
method: 'GET'
}, function(err, data) {
console.log('result, err: ' + err + ', data: ' + data);
});
Outputs:
res on end
result, err: null, data: �
socket on error
result, err: socket error: Error: Parse Error, data: undefined
Here are my questions:
Why res's 'end' event happened earlier than socket's 'error' event?
If I do want to callback an error when "Parse Error at Socket.ondata" happens like the above code or in any other situation, how to callback once instead of twice as the above output(IF res's 'end' event really hanppened earlier than socket's 'error' event)?
I need your help! Thanks.
===============================
I found the same code outputs:
res on end
result, err: null, data: �
in node v0.6.6 and v0.6.11. Why?

Because there's a content-length header of 1, when the request receives exactly 1 octet of data, it assumes that's all there is and fires the end callback. After that, more data is received that the socket doesn't know what to do with, so it fires the error.
To work around this, you could perhaps wait a short period before firing the callback for success and track if it's been fired. For example:
var req = http.request(options, function(res) {
var data = '';
res.setEncoding = 'utf8';
res.on('data', function(chunk) {
data += chunk;
});
res.on('error', function(err) {
if(!callback.called) { // check before firing the callback
callback(new Error('res error: ' + err));
callback.called = true; // set after firing the callback
} // ..
});
res.on('end', function() {
process.nextTick(function() { // use setTimeout if nextTick is too short
if(!callback.called) { //..
console.log('res on end');
callback(null, data);
callback.called = true; // ..
} // ..
}); // ..
});
});
req.on('socket', function(socket) {
socket.on('error', function(err) {
if(!callback.called) { // ..
console.log('socket on error');
callback('socket error: ' + err);
callback.called = true; // ..
} // ..
req.abort();
});
});
req.end();
(I tried to add comments after all of the new lines to make them stand out a little.)