firefly linux node 8.9.4 example fails unknown bus address

[dronesalot]

I'm trying to get the module to run on a small embedded device. I've installed it as per instructions. I took the example below directly from the README.

var dbus = require('dbus-native');
var sessionBus = dbus.sessionBus();
sessionBus.getService('org.freedesktop.Notifications').getInterface(
'/org/freedesktop/Notifications',
'org.freedesktop.Notifications', function(err, notifications) {

// dbus signals are EventEmitter events
notifications.on('ActionInvoked', function() {
    console.log('ActionInvoked', arguments);
});
notifications.on('NotificationClosed', function() {
    console.log('NotificationClosed', arguments);
});
notifications.Notify('exampl', 0, '', 'summary 3', 'new message text', ['xxx yyy', 'test2', 'test3', 'test4'], [],  5, function(err, id) {
   //setTimeout(function() { n.CloseNotification(id, console.log); }, 4000);
});

});

It fails with the following error:

/home/miker/test1/node_modules/dbus-native/index.js:22
if (!busAddress) throw new Error('unknown bus address');
^

Error: unknown bus address
at createStream (/home/miker/test1/node_modules/dbus-native/index.js:22:26)
at createConnection (/home/miker/test1/node_modules/dbus-native/index.js:76:31)
at Object.module.exports.createClient (/home/miker/test1/node_modules/dbus-native/index.js:136:20)
at Object.module.exports.sessionBus (/home/miker/test1/node_modules/dbus-native/index.js:149:25)
at Object. (/home/miker/test1/test.js:2:23)
at Module._compile (module.js:643:30)
at Object.Module._extensions..js (module.js:654:10)
at Module.load (module.js:556:32)
at tryModuleLoad (module.js:499:12)
at Function.Module._load (module.js:491:3)
miker@firefly:/test1$ node -v
v8.9.4
miker@firefly:/test1$ npm -v
6.0.0

[sidorares]

sessionBus() is a shortcut for "give me a client connected to address pointed by DBUS_SESSION_BUS_ADDRESS env variable", and in your case it's probably not set. Usually it's dbus-launch job to set it correctly, you neet to check who is launching dbus-daemon and maybe set DBUS_SESSION_BUS_ADDRESS manually if it's not set

[dronesalot]

I think you're correct, as I was running it from a shell and it appears to work when run in an xterm. One thing I wish for is better errors, or a troubleshooting type doc to help in these matters. I've spent the better part of the day trying to get notification of a USB mount event and I'm only slightly closer to a resolution.

[sidorares]

One thing I wish for is better errors, or a troubleshooting type doc

Yes, fully agree with you. This is something that definitely needs improvement

[dronesalot]

@sidorares I'm working on the udisk2 interface. Really, I just need to have a function called when a USB stick is inserted and the system mounts it (using automount).

Using dbus-monitor I can see the following message for the insertion:

signal time=1525065825.986584 sender=:1.59 -> destination=(null destination) serial=2187 path=/org/freedesktop/UDisks2; interface=org.freedesktop.DBus.ObjectManager; member=InterfacesAdded
   object path "/org/freedesktop/UDisks2/block_devices/sdb1"
   array [
      dict entry(
         string "org.freedesktop.UDisks2.Block"
         array [
            dict entry(
               string "Device"
               variant                   array of bytes "/dev/sdb1" + \0
            )
            dict entry(
               string "PreferredDevice"
               variant                   array of bytes "/dev/sdb1" + \0
            )
            dict entry(
               string "Symlinks"
               variant                   array [
                     array of bytes "/dev/disk/by-id/usb-Lexar_microSD_RDR_000000000001-0:0-part1" + \0
                     array of bytes "/dev/disk/by-path/platform-xhci-hcd.9.auto-usb-0:1.1.3:1.0-scsi-0:0:0:0-part1" + \0
                     array of bytes "/dev/disk/by-uuid/3A60-044B" + \0
[SNIP]

When the filesystem mount starts I see this:

signal time=1525065831.741319 sender=:1.59 -> destination=(null destination) serial=2190 path=/org/freedesktop/UDisks2; interface=org.freedesktop.DBus.ObjectManager; member=InterfacesAdded
object path "/org/freedesktop/UDisks2/jobs/206"
array [
dict entry(
string "org.freedesktop.UDisks2.Job"
array [
dict entry(
string "Operation"
variant string "filesystem-mount"
)
dict entry(
string "Progress"
variant double 0
)
[SNIP]

As job 206 runs, I see the mount point show up and the job completes.

signal time=1525065831.775012 sender=:1.59 -> destination=(null destination) serial=2191 path=/org/freedesktop/UDisks2/block_devices/sdb1; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
string "org.freedesktop.UDisks2.Filesystem"
array [
dict entry(
string "MountPoints"
variant array [
array of bytes "/media/miker/3A60-044B" + \0
]
)
]
array [
]
signal time=1525065831.798591 sender=:1.59 -> destination=(null destination) serial=2192 path=/org/freedesktop/UDisks2/jobs/206; interface=org.freedesktop.UDisks2.Job; member=Completed
boolean true
string ""

The trouble is, I can't figure out how to get the contents of these through dbus-native. I've messed with the code for a good 6 hours and every way I've tried to call GetAll it either dies with an exception or just returns an undefined var. Can you give me any pointers?

thanks

[sidorares]

As these are all signal the easiest way is just to listen all messages and check if message is from service

var dbus = require('dbus-native');
var conn = dbus.createConnection();
conn.on('message', function(msg) { 
  if (msg.path === '/org/freedesktop/UDisks2' && msg.member === 'InterfacesAdded' ) {
     console.log('Interface added: ', msg.body);
  } 
});

[dronesalot]

Not sure why, but that code does not seem to fire at all. Adding debugging in there shows it never runs. Any ideas?

var conn = dbus.createConnection();
conn.on('message', function(msg) {
console.log("Incoming: ",msg);
if (msg.path === '/org/freedesktop/UDisks2' && msg.member === 'InterfacesAdded' ) {
console.log('Interface added: ', msg.body);
}
});

[sidorares]

I'll try to test this code in couple of hours when I beck home at my desktop computer

[dronesalot]

This morning I tried a variety of things but the conn never seems to fire with messages. I'm not sure if it's a permissions thing or something else failing silently.

[dronesalot]

@sidorares I put another 5-6h of work into it. Still not getting anywhere. I wonder if you tested the script on your side? If it worked there, is there anything permissions-wise that could be interfering?

[sidorares]

so my example is definitely not enough. In order to receive signals client must send AddMatch message first

try this to see listen for all events:

var dbus = require('dbus-native');
var bus = dbus.sessionBus();
bus.connection.on('message', console.log);
bus.addMatch("type='signal'");
bus.addMatch("type='method_call'");
bus.addMatch("type='method_return'");
bus.connection.on('message', function(msg) {
  console.log(msg);
});

[dronesalot]

Thanks, the addMatch part really made a difference!

Is there anything documented on how to manage the msg object?

[sidorares]

Message is plain object, to better understand semantics of what's there best start is dbus spec: https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-messages

Also if you want to continue with "low level" approach (not via automatic introspection) section on match rules also useful: https://dbus.freedesktop.org/doc/dbus-specification.html#message-bus-routing-match-rules

[chris-ritsen]

I didn't know where to find the session bus address at first. This worked for me on Arch linux:
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus node index.js