Sunday, 28 August 2016

How to compile OpenVpn for Windows from source code

OpenVpn suggests cross-compilation - compiling Windows executables with Unix build toolchain. This can be accomplished either by using Linux/Unix or Cygwin on Windows.

This article demonstrates compiling OpenVpn with Cygwin on Windows.

The first step is to get build scripts from https://github.com/OpenVPN/openvpn-build.

When cloning OpenVpn repositories to Windows machine, make sure Git client for Windows does not automatically convert Unix-style line endings (LF) in source files into Windows-style line endings (CRLF). If this happens UNIX tools that run in Cygwin will report an error complaining about extra CR characters. So, when cloning, use the following command:


$ git clone https://github.com/OpenVPN/openvpn-build.git --config core.autocrlf=false



Required Cygwin packages are listed here: https://github.com/OpenVPN/openvpn-build/tree/master/generic

Package name Cygwin installer path
diffutils All --> Utils
m4All --> Interpreters
makeAll -> Devel
mingw64-i686-binutilsAll -> Devel
mingw64-i686-gcc-coreAll -> Devel
mingw64-i686-headersAll -> Devel
mingw64-i686-pthreadsAll -> Devel
mingw64-i686-runtimeAll -> Devel
mingw64-x86_64-binutilsAll -> Devel
mingw64-x86_64-gcc-coreAll -> Devel
mingw64-x86_64-headersAll -> Devel
mingw64-x86_64-pthreadsAll -> Devel
mingw64-x86_64-runtimeAll -> Devel
patchAll -> Devel
patchutilsAll -> Devel
perlAll --> Interpreters
unzipAll --> Archive
wgetAll --> Web


Download Perl script man2html and save it as a file with no extensions in /bin directory (C:\cygwin64\bin). Script URL is: http://cpansearch.perl.org/src/EHOOD/man2html3.0.1/man2html. If build is run with no having this script, the following error is reported at the output:


checking for man2html... no
configure: error: man2html is required for win32
FATAL: Configure pkcs11-helper



Make sure that man2html's shebang contains correct path to perl. In order to find perl's path in Cygwin we can do the following:


$ which perl
/usr/bin/perl



In my case shebang

#!/usr/local/bin/perl


has to be replaced with:

#!/usr/bin/perl



In order to build x64 version of OpenVpn go to ../OpenVpn/openvpn-build/generic and execute:

$ IMAGEROOT=`pwd`/image-win64 CHOST=x86_64-w64-mingw32 CBUILD=i686-pc-cygwin ./build




A bit about Cygwin

Checking whether some particular package has been installed (e.g. ca-certificates):

$ cygcheck -c ca-certificates
Cygwin Package Information
Package Version Status
ca-certificates 2.9-1 OK



http://stackoverflow.com/questions/9224298/how-do-i-fix-certificate-errors-when-running-wget-on-an-https-url-in-cygwin

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