How to compile LAN Messenger

You need Qt (https://www.qt.io/) and CMake (https://cmake.org/) to compile. LAN Messenger is built against Qt 6 and enforces the Qt 6 API baseline (QT_DISABLE_DEPRECATED_BEFORE=0x060000), so you need Qt 6.4 or later. The reference builds use Qt 6.8.3 on Windows and macOS and the distribution Qt 6.4 packages on Linux. CMake 3.16 or later and a C++17 compiler are required.

You also need OpenSSL (http://www.openssl.org/) Version 1.1 or later, including 3.x, is supported. Only libcrypto is linked at build time; the libssl runtime DLLs are still copied next to the binary on Windows.

The application consists of two projects - lmc and lmcapp. lmcapp is just an extension of the qtsingleapplication project released by the Qt people. I have added a few functions to support multilanguage UI.

The main project is lmc which contains the entire application. Both projects are built together by the top-level CMake project (CMakeLists.txt in the repository root).

The code is identical for all platforms, but there are a few differences in the way application is built and run on each platform. Please read the platform specific notes to know more.

The GitHub Actions workflow .github/workflows/ci.yml is the reference build for all three platforms. If you run into setup problems, compare your environment with the steps in that file.

Note: Qt Creator IDE works well on all platforms. The CI build uses MSVC on Windows, gcc on Linux and Apple clang on macOS. If you are using any other IDE and/or compiler and run into any issue, I can only provide generic help.

Important: Its better if your project paths do not contain any white spaces. Some tools do not work properly with paths containing spaces. Use paths that do not have spaces to avoid headaches down the lane. Saving project files to your dektop is a BAD idea.

Compiling/Installing OpenSSL

If precompiled binary distribution of OpenSSL is available for your platform, you can use it instead of building from source.

The steps for compiling OpenSSL varies depending on your platform. The package that you get from OpenSSL website gives detailed instructions on how to compile on all supported platforms. OpenSSL itself may need additional software packages to compile depending on your system.

Make sure that OpenSSL is built as a shared library.

Windows

Get a prebuilt 64-bit OpenSSL 3.x distribution. The CI build installs it with vcpkg:

vcpkg install openssl:x64-windows

The Win64 OpenSSL 3.x package from http://www.slproweb.com/products/Win32OpenSSL.html works too. While installing it, make sure that the option to copy DLLs to the OpenSSL binaries directory is selected in the Additional Tasks page.

Whatever source you use, lay the files out in a folder called "openssl" which should be at the same level as the folder "lmc": openssl |-bin (libcrypto-.dll, libssl-.dll) |-include (openssl headers) |-lib (libcrypto.lib, libssl.lib)

The build step copies the runtime DLLs from openssl\bin to the output folder.

Linux/X11

Many Linux distributions come with pre-compiled OpenSSL packages. If your system has one, you may be able to link the project to it. If your system lacks the package, or if you are unable to link with it, you need to build OpenSSL from source.

Specify the "shared" switch to ensure that OpenSSL is built as a shared library.

The CI build simply points the openssl folder at the system OpenSSL:

mkdir openssl ln -sfn /usr/include openssl/include ln -sfn /usr/lib/x86_64-linux-gnu openssl/lib

Mac OS X

Mac OS X does not ship a linkable OpenSSL. The CI build installs it with Homebrew:

brew install openssl@3

and points the openssl folder at the Homebrew prefix:

mkdir openssl ln -sfn "$(brew --prefix openssl@3)/include" openssl/include ln -sfn "$(brew --prefix openssl@3)/lib" openssl/lib

Compiling LAN Messenger

Configure and build from the repository root:

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release cmake --build build --config Release --target package-local --parallel

The "package-local" target stages the complete runtime bundle (the application binary, the lmcapp library, translations, the resource bundle, themes, sounds and the Qt image/platform/TLS plugins) into the LMC_RELEASE_DIR directory, which defaults to /release. The packaging scripts under lmc/setup expect the layout in lmc/release, so pass -DLMC_RELEASE_DIR="$PWD/lmc/release" when you plan to build the install packages (this is what the CI build does).

If OpenSSL is laid out in the "openssl" folder described above, pass -DOPENSSL_ROOT_DIR=$PWD/openssl to the configure command. Otherwise the system OpenSSL found by CMake is used.

Refer PLATFORM_SPECIFIC.md for additional details about setting up the build environment on respective platforms.

Compiling LAN Messenger on Windows

Its possible to compile using other build chains/IDEs, but the CI build uses CMake with the MSVC tool chain.

OpenSSL should be built/installed first. I recommend using a folder at the same level as "lmc" folder as the OpenSSL folder.

Build as described in the previous section. The application binary is lmc.exe and lmcapp is built as lmcapp.dll with the import library lmcapp.lib (no renaming needed). The package-local target copies the OpenSSL runtime DLLs from openssl\bin to the output folder.

To gather the Qt libraries and plugins into the output folder, run "windeployqt --release \lmc.exe" afterwards, as done in the CI build. The Qt 6 TLS backend plugins (the "tls" folder) are needed for SSL support; copy them from your Qt installation's plugins\tls folder into the output "tls" folder if windeployqt skipped them.

To build the installer, run "setup.bat" in lmc\setup\win32 folder. NSIS must be installed first. Usage: setup.bat [ProductVersion] [InstallerVersion] Eg: setup.bat release 1.2.39 1.2.3.9

The batch file executes an NSIS script (setup.nsi) which packages the whole ExeFolder and generates the installer. ProductVersion and InstallerVersion are passed to makensis as command line defines; when omitted, the defaults in setup.nsi are used and must be set whenever the application version changes. The installer generated will have the name lmc--win64.exe and it will be saved to lmc\setup folder.

Compiling LAN Messenger on X11/Linux

OpenSSL should be built first. I recommend using a folder at the same level as "lmc" folder as the OpenSSL folder. Distribution packages work too (see the OpenSSL section above).

Build as described earlier and launch the application through the "lan-messenger.sh" script in the release layout. It sets the load paths for the bundled libraries and calls the "whitelist" helper internally (needed for the system tray icon on Ubuntu). Both scripts are staged with executable permission by the package-local target.

For building the installer, run the bash script "setup" in lmc/setup/x11 folder. Make sure the scripts named "postinst", "postrm" and "prerm" in the folder package/DEBIAN have executable permission. The setup script substitutes the version and architecture placeholders (VERSION, ARCH) in the file "control" in the same folder from its argument; edit that file to reflect the proper installed size (in KB) of the application. The scripts "lmc.sh" and "whitelist" in package/usr/lib/lmc must also have executable permission. All files and folder inside package folder must be owned by root user.

The setup script generates the deb installation package which will be saved to lmc/setup folder. The package will have the name lmc__.deb (eg: lmc_1.2.39_x86_64.deb). Set the environment variable PACKAGE_MODE=_min to build a minimal package that does not bundle the Qt libraries (this is what the CI build produces); without it the package also bundles the Qt 6 libraries the application links and the plugins they need. For generating rpm package, alien must be installed first. To install alien, run: sudo apt-get install alien Execute "rpm_setup" script in lmc/setup/x11 to generate an rpm package from the deb package (deb package must be created first). This package will have the name lmc-..rpm and will be saved to lmc/setup folder.

Compiling LAN Messenger on Mac OS X

Build as described earlier; the result is LAN-Messenger.app in the release layout. The lmcapp helper (liblmcapp.2.dylib) is placed inside the bundle with load path @executable_path.

Note: Mac OS X does not ship a linkable OpenSSL. Install it as described in the OpenSSL section above and pass -DOPENSSL_ROOT_DIR when configuring.

For building the installer, first run the bash script "createdisk" in lmc/setup/mac folder. This copies the app bundle, runs macdeployqt on it to collect the Qt frameworks and creates a disk image with all the required files needed for the application. The script finds macdeployqt through the QTDIR environment variable, so make sure it points at your Qt installation (the parent folder of the bin and lib folders). Now open up the disk image, set the background image, icon size (96x96), icon position, icon arrangment (Snap to Grid) and window size. Now run the script "addlicense" to add the user license and compress the disk image ("addlicense [intel|arm64]", default intel). The dmg file will have the name lmc_intel.dmg (Intel, CI job build-macos-intel) or lmc_arm64.dmg (Apple Silicon, CI job build-macos-arm64) and will be saved to lmc/setup folder.

Note: On Mac OS X, option to start LAN Messenger on startup will not work. This is a platform dependent function and I have not implemented it.

Audio playback support

LAN Messenger can play sounds to accompany certain events. This behaviour is customizable in the Preferences dialog. Sounds are played through the Qt Multimedia module (QSoundEffect), so that module must be available at build and run time. On Linux install the Qt Multimedia development and runtime packages (qt6-multimedia-dev, libqt6multimedia6). If no audio output device is available, the sound options will be grayed out in the Preferences dialog.

System tray support

On desktops that do not have a system tray, the system tray options will be grayed out in the Preferences dialog.