Category: Development


resolv_wrapper 1.0.0 – the new cwrap tool

I’ve released a new preloadable wrapper named resolv_wrapper which can be used for nameserver redirection or DNS response faking. It can be used in testing environment to route DNS queries to a real nameserver separate from resolv.conf or fake one with simple config file. We tested it on Linux, FreeBSD and Solaris. It should work on other UNIX flavors too. You can download resolv_wrapper here.


A talk about cwrap at LinuxCon Europe

Next week is the LinuxCon Europe in Düsseldorf, Germany. I will be there and give a talk about cwrap, a set of tools to make client/server testing easy on a single machine. Testing network applications correctly is hard. This talk will demonstrate how to create a fully isolated network environment for client and server testing on a single host, complete with synthetic account information, hostname...


How to get real DNS resolving in ‘make test’?

As you might know I’m working (hacking) on Samba. Samba has a DNS implementation to easier integrate all the AD features. The problem is we would like to talk to the DNS server but /etc/resolv.conf points to a nameserver so your machine is correctly working in your network environment. For this Samba in our dns resolver library we implemented a way to setup a dns_hosts_file...


What is preloading?

by Jakub Hrozek and Andreas Schneider The LD_PRELOAD trick! Preloading is a feature of the dynamic linker (ld). It is a available on most Unix system and allows to load a user specified, shared library before all other shared libraries which are linked to an executable. Library pre-loading is most commonly used when you need a custom version of a library function to be called....


New features in socket_wrapper 1.1.0

Maybe you already heard of the cwrap project. A set of tools to create a fully isolated network environment to test client/server components on a single host. socket_wrapper is a part of cwrap and I released version 1.1.0 today. In this release I worked together with Michael Adam and we implemented some nice new features like support for IP_PKTINFO for binding on UDP sockets, bindresvport()...


Group support for cmocka

Last Friday I’ve released cmocka 0.4.0. It has several bugfixes and at least two new features. One is support for groups. This means you can define a setup and teardown function for a group of unit tests. I think some people have been waiting for this. You can find an example here. It is simple and easy to use. The other small feature is a...


The Gold Linker

After the Update to Fedora 20 I forgot to update the linker to Gold. Today I released that linking Samba is horribly slow. Time to change the linker to Gold again: Fedora: ll /etc/alternatives/ld /usr/sbin/alternatives –set ld /usr/bin/ openSUSE: ll /etc/alternatives/ld /usr/sbin/update-alternatives –set ld /usr/bin/ To still build a special project with ld.bfd use: LDFLAGS=”-fuse-ld=bfd”


cwrap 1.0.0 – testing your full software stack …

on one single machine! FOSDEM/Brussels, February 2nd, I gave a talk about cwrap. I announced and released version 1.0.0 of cwrap, a set of tools to create a fully isolated network environment to test client/server components on a single host. It provides synthetic account information, hostname resolution and privilege separation support. The heart of cwrap consists of three libraries you can preload to any executable....


FOSDEM: My talk about cwrap

Next weekend, February 1st and 2nd, will be the FOSDEM conference in Brussels again. I will be there and give a talk in the Testing and Automation devroom. I hope you will be there and watch my presentation on Sunday, February 2nd, 11:30, Room: UD2.218A. See you there!