DBus service

See also: DBus man page.

signal-cli can run in daemon mode and provides an experimental dbus interface.

• Run in daemon mode (dbus session bus)

  signal-cli [-u USERNAME] daemon
  

• Send a message via dbus

  signal-cli --dbus send -m "Message" [RECIPIENT [RECIPIENT ...]] [-a [ATTACHMENT [ATTACHMENT ...]]]
  

MacOS

MacOS users can run the following commands if needed:

brew install dbus
brew services start dbus

The environment variable DBUS_LAUNCHD_SESSION_BUS_SOCKET needs to be set correctly. If it has not been, you will see error messages similar to those in the Troubleshooting section below. If that happens, issue this command:

export DBUS_LAUNCHD_SESSION_BUS_SOCKET=$(launchctl getenv DBUS_LAUNCHD_SESSION_BUS_SOCKET)

In particular, this command needs to be issued if you manually start or restart the Dbus service:

brew services restart dbus
export DBUS_LAUNCHD_SESSION_BUS_SOCKET=$(launchctl getenv DBUS_LAUNCHD_SESSION_BUS_SOCKET)

System bus

To run on the system bus you need to take some additional steps. It’s advisable to run signal-cli as a separate unix user, the following steps assume you created a user named signal-cli. To run a service on the system bus, a config file is needed to allow the signal-cli user to take a name on the system bus. An example config file can be found in data/org.asamk.Signal.conf. This file also configures that any user can talk with the signal-cli daemon. The data/org.asamk.Signal.service and data/signal-cli.service files configure a dbus activated systemd service for signal-cli, so the service is automatically started when the dbus service is requested.

These steps, executed as root, should work on all distributions using systemd.

cp data/org.asamk.Signal.conf /etc/dbus-1/system.d/
cp data/org.asamk.Signal.service /usr/share/dbus-1/system-services/
cp data/signal-cli.service /etc/systemd/system/
sed -i -e "s|%dir%|<INSERT_INSTALL_PATH>|" /etc/systemd/system/signal-cli.service
systemctl daemon-reload
systemctl enable signal-cli.service
systemctl reload dbus.service

Mind the fact that signal-cli.service executes the signal-cli with "--config /var/lib/signal-cli". If you registered with user signal-cli, remove the config option.

Make sure to use "--dbus-system" with the send command, the service will be autostarted by dbus the first time it is requested.

Send using dbus-send

To avoid the startup time of the JVM for the dbus client, you can use any dbus capable program to send messages via the signal-cli dbus daemon. Example with dbus-send:

dbus-send --session --type=method_call --print-reply --dest="org.asamk.Signal" /org/asamk/Signal org.asamk.Signal.sendMessage string:MessageText array:string: string:RECIPIENT

Example if you started the daemon without the optional USERNAME (exports all local users):

dbus-send --session --type=method_call --print-reply --dest="org.asamk.Signal" /org/asamk/Signal/_33123456789 org.asamk.Signal.sendMessage string:MessageText array:string: string:RECIPIENT

Keep in mind that if you use DBus as a system service and want to send a message using the dbus daemon, you must use --system instead of --session in the dbus send command.

For an example of sending a group message through the dbus interface, see #272.

Receive messages from signal-cli daemon

The signal-cli daemon publishes new messages to dbus.

Here's an example using python:

def msgRcv (timestamp, source, groupID, message, attachments):
   print ("Message", message, "received in group", signal.getGroupName (groupID))
   return

from pydbus import SystemBus
from gi.repository import GLib

bus = SystemBus()
loop = GLib.MainLoop()

signal = bus.get('org.asamk.Signal') 
# NOTE: when daemon was started without explicit `-u USERNAME`, replace the line above with
# signal = bus.get("org.asamk.Signal", "/org/asamk/Signal/_YOURPHONENUMBER")

signal.onMessageReceived = msgRcv
loop.run()

Here's an example using Perl:

#!/bin/perl

use Modern::Perl;

use Net::DBus;
use Net::DBus::Reactor;

sub msgRcv {
    my ($timestamp, $sender, $groupID, $message, $attachments) = @_;
    print "Message: $message\nSender: $sender\nTimestamp: $timestamp\nAttachments: $attachments\n";
    return;
}

my $bus = Net::DBus->system();
my $sig = $bus->get_service("org.asamk.Signal");
my $obj = $sig->get_object("/org/asamk/Signal","org.asamk.Signal");
my $sigid = $obj->connect_to_signal('MessageReceived', \&msgRcv);

my $reactor=Net::DBus::Reactor->main();
$reactor->run();

exit 0;

Troubleshooting

DBus exception when starting daemon

$ signal-cli daemon
org.freedesktop.dbus.exceptions.DBusException: Cannot Resolve Session Bus Address
	...

	--- OR --- 

org.freedesktop.dbus.exceptions.DBusException: Failed to connect to bus: No such file or directory
	...

Environment variable DBUS_SESSION_BUS_ADDRESS needs to be set. See #394 and links to other issues in it.

Under Mac OSX, the environment variable DBUS_LAUNCHD_SESSION_BUS_SOCKET needs to be set (see above). This can be done by issuing the command

export DBUS_LAUNCHD_SESSION_BUS_SOCKET=$(launchctl getenv DBUS_LAUNCHD_SESSION_BUS_SOCKET)