Wayland μSynergy

An implementation of a Synergy client for wlroots compositors. Based on the upstream μSynergy library (heavily modified for more protocol support and a bit of paranoia).

Getting started

Prerequisites

• wayland, including wayland-scanner and the base protocols
• libxkbcommon
• libtls (either from libressl, or libretls)
• A compositor making use of wlroots
• wl-clipboard for clipboard support

Building

meson build
cd build
ninja
ninja install

Running

See

waynergy -h

output:

waynergy: Synergy client for wlroots compositors

USAGE: waynergy [-h|--help] [-c|--host host] [-p|--port port] [-W|--width width] [-H|--height height] [-N|--name name] [-l|--logfile file] [-L|--loglevel level] [-n|--no-clip] [--fatal-none] [--fatal-ebad] [--fatal-ebsy] [--fatal-timeout]
	-h|--help:
		Help text
	-c|--host host:
		Server to connect to
	-p|--port port:
		Port
	-W|--width width:
		Width of screen in pixels (manual override, must be given with height)
	-H|--height height:
		Height of screen in pixels (manual override, must be given with width)
	-N|--name name:
		Name of client screen
	-l|--logfile file:
		Name of logfile to use
	-L|--loglevel level:
		Log level -- number, increasing from 0 for more verbosity
	-n|--no-clip:
		Don't synchronize the clipboard
	-e|--enable-crypto:
		Enable TLS encryption
	-t|--enable-tofu:
		Enable trust-on-first-use for TLS certificate
	--fatal-none:
		Consider *normal* disconnect (i.e. CBYE) to be fatal
	--fatal-ebad:
		Protocol errors are fatal
	--fatal-ebsy:
		EBSY (client already exists with our name) errors are fatal
	--fatal-timeout:
		timeouts are fatal

Also note that SIGUSR1 triggers re-execution. Useful until proper recconect procedures exist.

Configuration

The configuration files are stored in $XDG_CONFIG_HOME/waynergy, which is probably at ~/.config/waynergy in most cases. A single variable goes into each file named for the setting, because parsing is for those who are not lazy.

The basics are port, host, name, width, and height, which do exactly what the command line option would do.

Keymap

There's also an xkb format keymap to provide, if the default is not sufficient; it should be placed in xkb_keymap. The easiest way to obtain this if the default is insufficient is to use the output of

setxkbmap -print

Windows primary

Unfortunately there is no existing xkb_keycodes section included in xkbcommon that will work with a Windows primary. To deal with this I've included one that mostly works (minus the keys I don't actually have to test on my own systems) in doc/xkb/keycodes/win.

Screensaver

screensaver/start should contain a command to be run when the screensaver is activated remotely, screensaver/stop should contain a command to terminate it when it is deactivated.

Idle inhibition hack

Due to issues with the idle inhibition protocol, idle is actually inhibited by sending a hopefully-meaningless event to the compositor: if idle-inhibit/method is key, the key associated with the xkb-style name in idle-inhibit/keyname is pressed (defaults to HYPR). If idle-inhbibit/method is mouse, then a relative move of 0,0 is sent (this is the default).

The mouse approach prevents any clashes with keys, but will prevent cursor hiding.

TLS

Enabled or disabled with tls/enable. Certificate hashes (for any given host) are stored in the directory tls/hash/, one hash per file named after the host. These can be obtained by running something like

printf "SHA256:%s\n" $(openssl x509 -outform der -in $certpath | openssl dgst -sha256 | cut -d ' ' -f 2)

on the host. Comman values of $certpath would be

• %LocalAppData%\Barrier\SSL\Barrier.pem
• ~/.local/share/barrier/SSL/Barrier.pem
• $XDG_DATA_HOME/barrier/SSL/Barrier.pem
• ~/.synergy/SSL/Synergy.pem

There is also the option to trust on first use by setting tls/tofu or running with the --enable-tofu option on the command line, which will allow verification that it has not changed on subsequent connections.

Acknowledgements

• uSynergy for the protocol library
• The swaywm people, who've provided the protocols to make something like this possible
• wl-clipboard, because its watch mode turns it into a clipboard manager so I I don't have to.

TODO

• use the wayland protocols for clipboard management. wl-clipboard already existed and is mostly fine, but Synergy specifies the format of the data (negating the need to guess at mimetypes) and multi-process coordination is annoying.
• De-uglify. This was one of those let's-not-really-plan-this-out-but-write-vaguely-working-code sort of things, and it shows, quite noticeably.