Native messaging problem

[Fernando Sanchez Ortega]

Hi there, 

I am trying to create a simple Native messaging application on my MacOS.

I was following the steps discussed in the following link:
https://developer.chrome.com/docs/extensions/mv3/nativeMessaging/

I was able to open any application that I have installed in my MacOS such as Slack, vscode etc etc.

I was wondering if I could launch a script that I have in my extension folder, or a python3 application... because everytime that I try to launch some of these kind of files it return me the following error::

Failed to connect: Failed to start native messaging host.

I will attach the JS code that is using to send the information and the manifest.

popup.js:

var port = null;

var getKeys = function(obj){

var keys = [];

for(var key in obj){

keys.push(key);

}

return keys;

}

function appendMessage(text) {

document.getElementById('response').innerHTML += "<p>" + text + "</p>";

}

function updateUiState() {

if (port) {

document.getElementById('connect-button').style.display = 'none';

document.getElementById('input-text').style.display = 'block';

document.getElementById('send-message-button').style.display = 'block';

} else {

document.getElementById('connect-button').style.display = 'block';

document.getElementById('input-text').style.display = 'none';

document.getElementById('send-message-button').style.display = 'none';

}

}

function sendNativeMessage() {

message = {"text": document.getElementById('input-text').value};

port.postMessage(message);

appendMessage("Sent message: <b>" + JSON.stringify(message) + "</b>");

}

function onNativeMessage(message) {

appendMessage("Received message: <b>" + JSON.stringify(message) + "</b>");

}

function onDisconnected() {

appendMessage("Failed to connect: " + chrome.runtime.lastError.message);

port = null;

updateUiState();

}

function connect() {

var hostName = "com.google.chrome.example.echo";

appendMessage("Connecting to native messaging host <b>" + hostName + "</b>")

port = chrome.runtime.connectNative(hostName);

port.onMessage.addListener(onNativeMessage);

port.onDisconnect.addListener(onDisconnected);

updateUiState();

}

document.addEventListener('DOMContentLoaded', function () {

document.getElementById('connect-button').addEventListener(

'click', connect);

document.getElementById('send-message-button').addEventListener(

'click', sendNativeMessage);

updateUiState();

});

Manifest.js

{

// Extension ID: knldjmfmopnpolahpmmgbagdohdnhkik

"key": "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDcBHwzDvyBQ6bDppkIs9MP4ksKqCMyXQ/A52JivHZKh4YO/9vJsT3oaYhSpDCE9RPocOEQvwsHsFReW2nUEc6OLLyoCFFxIb7KkLGsmfakkut/fFdNJYh0xOTbSN8YvLWcqph09XAY2Y/f0AL7vfO1cuCqtkMt8hFrBGWxDdf9CQIDAQAB",

"name": "Chrome Extension binaryMessaging MV3",

"description": "Learning limitations and use of binaries",

"version": "0.1.0",

"manifest_version": 3,

"icons": {

"16": "/images/Z.png",

"32": "/images/Z.png",

"48": "/images/Z.png",

"128": "/images/Z.png"

},

"background": {

"service_worker": "background.js"

},

"action": {

"default_popup": "popup.html",

"default_icon": {

"16": "/images/Z.png",

"32": "/images/Z.png",

"48": "/images/Z.png",

"128": "/images/Z.png"

}

},

"permissions": [

"nativeMessaging"

]

}

Thanks in advance!

[Oliver Dunk]

Hi Fernando,

That should definitely be possible.

There's an MV2 example here: https://github.com/GoogleChrome/chrome-extensions-samples/tree/main/_archive/mv2/api/nativeMessaging

Is it possible you haven't set the write permissions on the file or included `#!/usr/bin/env python` to mark the file as a Python executable?

Oliver Dunk | DevRel, Chrome Extensions | https://developer.chrome.com/ | London, GB

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[Fernando Sanchez Ortega]

Hi Oliver, 

Thanks for your quick response:

I give them all the permission just in case xd:

I will share with you more information:
com.google.chrome.example.echo.json:
// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
{
  "name": "com.google.chrome.example.echo",
  "description": "Chrome Native Messaging API Example Host",
  "path": "/Applications/native-messaging-example-host",
  "type": "stdio",
  "allowed_origins": [
    "chrome-extension://knldjmfmopnpolahpmmgbagdohdnhkik/"
  ]
}

The code in python is exactly the same one of the repository that you shared with me, and the permission given to the python application are:

-rwxrwxrwx@  1 fernando  admin  3605 Nov  9 10:45 native-messaging-example-host

Any idea?

[Oliver Dunk]

Hmm, that seems ok to me then.

Do you definitely have Python installed and available as `python` in your command line?

Oliver Dunk | DevRel, Chrome Extensions | https://developer.chrome.com/ | London, GB

[Fernando Sanchez Ortega]

yeah :(! 

I can run it from a simple terminal without problem:

`python`
Python 2.7.18 (v2.7.18:8d21aa21f2, Apr 19 2020, 20:48:48)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information

Also the python application is working when I call it.

[Oliver Dunk]

Hmm, that all seems fine to me.

And if you run `/Applications/native-messaging-example-host` in the terminal (just that, without python beforehand) it works?

Oliver Dunk | DevRel, Chrome Extensions | https://developer.chrome.com/ | London, GB