NAME

       resolv_wrapper - A wrapper for dns name resolving or dns faking.

SYNOPSIS

       LD_PRELOAD=libresolv_wrapper.so RESOLV_WRAPPER_CONF="/path/to/resolv.conf" ./myapplication

DESCRIPTION

       resolv_wrapper makes it possible on most UNIX platforms to contact your own DNS
       implementation in your test environment. It requires socket_wrapper to be able to contact
       it. If it doesn’t work on a special platform the wrapper is able to fake DNS queries and
       return valid responses to your application.

       •   Redirects name queries to the nameservers specified in your resolv.conf

       •   Can fake DNS queries using a simple formatted DNS hosts file.

ENVIRONMENT VARIABLES

       RESOLV_WRAPPER_CONF
           This is used to specify the resolv.conf to use. The format of the resolv.conf file is
           defined in the manpage resolv.conf(5). Currently only the namserver directive is
           supported.

       In order that this works with socket_wrapper. The res_* symbols need to be in a separate
       libresolv library. If they are part of libc this wont work. This is the case with glibc >=
       2.34.

       RESOLV_WRAPPER_HOSTS
           This environment variable is used for faking DNS queries. It must point to a
           hosts-like text file that specifies fake records for custom queries. The format of the
           file looks like this:

               TYPE    RECORD_NAME RECORD_VALUE

       For example:

           A       dc.cwrap.org 127.0.0.10
           AAAA    dc.cwrap.org fd00::5357:5f0a
           CNAME   kerberos.cwrap.org dc.cwrap.org
           SRV     _kerberos._tcp.cwrap.org kerberos.cwrap.org 88
           URI     _vpn.cwrap.org https://vpn.cwrap.org/VPN
           TXT     cwrap.org v=spf1 mx

       RESOLV_WRAPPER_DEBUGLEVEL
           If you need to see what is going on in resolv_wrapper itself or try to find a bug, you
           can enable logging support in resolv_wrapper if you built it with debug symbols.

           •   0 = ERROR

           •   1 = WARNING

           •   2 = DEBUG

           •   3 = TRACE

       RESOLV_WRAPPER_DISABLE_DEEPBIND
           This allows you to disable deep binding in resolv_wrapper. This is useful for running
           valgrind tools or sanitizers like (address, undefined, thread).

EXAMPLE

       The following command would trick kinit(1) into using DNS servers from "./resolv.conf" for
       Kerberos service resolution:

           $ LD_PRELOAD=libresolv_wrapper.so RESOLV_WRAPPER_CONF="./resolv.conf" kinit user@EXAMPLE.COM

AUTHOR

       The Samba Team

                                            2023-08-06                          RESOLV_WRAPPER(1)