Howto: cross-compiling tinc for Windows under Linux using MinGW
This howto describes how to create a Windows binary of tinc. Although it is possible to compile tinc under Windows itself, cross-compiling it under Linux is much faster. It is also much easier to get all the dependencies in a modern distribution. Therefore, this howto deals with cross-compiling tinc with MinGW under Linux on a Debian distribution.
The result is a 32-bit executable. If you want to create a 64-bit executable, have a look at the 64-bit cross-compilation example.
Overview
The idea is simple:
- Install MinGW and Wine.
- Create a directory where we will perform all cross-compilations.
- Get all the necessary sources.
- Cross-compile everything.
Installing the prerequisites for cross-compilation
There are only a few packages that need to be installed as root to get started:
sudo apt-get install mingw32 wine git-core
sudo apt-get build-dep tinc
Other Linux distributions may also have MinGW packages, use their respective
package management tools to install them. Debian installs the cross-compiler
in /usr/i586-mingw32msvc/. Other distributions might install it in another
directory however, for example /usr/i686-pc-mingw32/. Check in which directory
it is installed, and replace all occurences of i586-mingw32msvc in this
example with the correct name from your distribution.
Setting up the build directory and getting the sources
We will create a directory called mingw/ in the home directory. We use
apt-get to get the required libraries necessary for tinc, and use git to get
the latest development version of tinc.
mkdir $HOME/mingw
cd $HOME/mingw
apt-get source openssl liblzo2-dev zlib1g-dev
git clone git://tinc-vpn.org/tinc
Making cross-compilation easy
To make cross-compiling easy, we create a script called mingw that will set
up the necessary environment variables so configure scripts and Makefiles will
use the MinGW version of GCC and binutils:
mkdir $HOME/bin
cat >$HOME/bin/mingw << EOF
#!/bin/sh
export CC=i586-mingw32msvc-gcc
export CXX=i586-mingw32msvc-g++
export CPP=i586-mingw32msvc-cpp
export RANLIB=i586-mingw32msvc-ranlib
export PATH="/usr/i586-mingw32msvc/bin:$PATH"
exec "$@"
EOF
chmod u+x $HOME/bin/mingw
If $HOME/bin is not already part of your $PATH, you need to add it:
export PATH="$HOME/bin:$PATH"
We use this script to call ./configure and make with the right environment
variables, but only when the ./configure script doesn’t support cross-compilation itself.
You can also run the export commands from the mingw script by
hand instead of calling the mingw script for every ./configure or make
command, or execute $HOME/bin/mingw $SHELL to get a shell with these
environment variables set, but in this howto we will call it explicitly every
time it is needed.
Compiling LZO
Cross-compiling LZO is easy:
cd $HOME/mingw/lzo2-2.03
./configure --host=i586-mingw32msvc
make
DESTDIR=$HOME/mingw make install
Compiling Zlib
Cross-compiling Zlib is also easy, but a plain make failed to compile the
tests, so we only build the static library here:
cd $HOME/mingw/zlib-1.2.3.3.dfsg
mingw ./configure
mingw make libz.a
DESTDIR=$HOME/mingw mingw make install
Compiling OpenSSL
OpenSSL is always a bit hard to compile, because they have their own
Configure script that needs some tweaking. There is also a small bug in
e_os2.h in OpenSSL 0.9.8 that breaks compilation with recent versions of GCC.
If you have this version of OpenSSL, then first download
this openssl-cross-compilation.diff to your home directory, then patch
OpenSSL:
cd $HOME/mingw/openssl-0.9.8k
patch < $HOME/openssl-cross-compilation.diff
With OpenSSL 1.0.0, this problem is no longer present. However, apt-get source will have applied
Debian-specific patches that break cross-compiling a Windows binary. You need to undo those patches first:
cd $HOME/mingw/openssl-0.9.8k
quilt pop -a
Now you can compile OpenSSL.
Do not use the -j option when compiling OpenSSL, it will break.
mingw ./Configure --openssldir=$HOME/mingw/usr/local mingw
mingw make
mingw make install
Compiling tinc
Now that all the dependencies have been cross-compiled, we can cross-compile
tinc. Since we use a clone of the git repository here, we need to run
autoreconf first. If you want to cross-compile tinc from a released tarball,
this is not necessary.
cd $HOME/mingw/tinc
autoreconf -fsi
./configure --host=i586-mingw32msvc --with-openssl=$HOME/mingw/usr/local
make
Testing tinc
Since Wine was installed, you can execute the resulting binary even on Linux. You cannot do much however, since tinc requires a TAP-Win32 device, which is not available in Wine. Still, the following command should work:
$HOME/mingw/tinc/src/tincd.exe --help