runidn - A script to allow applications to use internationalized domain
runidn [-e local-codeset] program-name [args..]
runidn enables applications to use internationalized domain names with
out recompilation. Just add runidn before the application-name,
and the application can handle non-ASCII domain names. For example,
you can do:
% runidn telnet non-ASCII-hostname
Before using runidn, you should set up properties related to interna
tionalized DNS by configuring idnkits configuration file idn.conf.
See idn.conf(5) which describes the configuration.
The following option is available:
Specify the applications local codeset. If the option is not
specified, runidn guesses the codeset from the current locale. See
the NOTE section for more details about local codeset.
runidn is a small shell script that sets up an environment variable
called LD_PRELOAD, so that an application dynamically links a
shared library libidnkitres before any other shared libraries.
The library libidnkitres provides a special version of resolver
functions which implement features for handling internationalized
domain names. runidn replaces the following functions with the special
By overriding them in the standard libraries with the special version
provided by libidnkitres, runidn enables applications to use inter
nationalized domain names.
These API functions accept non-ASCII domain names encoded in the
local codeset that the application is using. Also the result
from these APIs may contain non-ASCII domain names.
The normalization and codeset conversion between applications
local codeset and the codeset used in DNS protocol data are han
dled automatically, so users/applications need not worry about
Properties of internationalized DNS (such as the normalization or the
codeset used on DNS protocol data) can be configured with the idnkits
configuration file (idn.conf). See idn.conf(5) for details.
Unless -e option is specified, runidn tries to guess the applications
local codeset from the applications current locale. However, some
times it cannot guess the codeset correctly, for example if the appli
cation does not set the locale appropriately by calling setlocale().
In that case, you can explicitly specify the local codeset by setting
an environment variable IDN_LOCAL_CODESET. See the section LOCAL
CODESET in idn.conf(5) for details.
The idea of using LD_PRELOAD to replace some functions in the stan
dard library was taken from runsocks script distributed as part of
SOCKS5 reference implementation.
There are many cases where runidn does not work.
Your system must support LD_PRELOAD mechanism in the first place.
Due to security reasons, LD_PRELOAD mechanism is disabled for
setuid programs in any sane systems. So runidn does not work for
setuid programs such as ping or rsh.
If your application uses a function other than the ones runidn supports
for name resolution, you lose.
April 6, 2001 RUNIDN(1)