3 :author: The Samba Team
9 resolv_wrapper - A wrapper for dns name resolving or dns faking.
14 LD_PRELOAD=libresolv_wrapper.so RESOLV_WRAPPER_CONF="/path/to/resolv.conf" *./myapplication*
19 resolv_wrapper makes it possible on most UNIX platforms to contact your own DNS
20 implementation in your test environment. It requires socket_wrapper to be able
22 If it doesn't work on a special platform the wrapper is able to fake DNS queries
23 and return valid responses to your application.
25 - Redirects name queries to the nameservers specified in your resolv.conf
26 - Can fake DNS queries using a simple formatted DNS hosts file.
31 *RESOLV_WRAPPER_CONF*::
33 This is used to specify the resolv.conf to use. The format of the resolv.conf
34 file is defined in the manpage 'resolv.conf(5)'. Currently only the *namserver*
35 directive is supported.
37 In order that this works with socket_wrapper. The res_* symbols need to be in
38 a separate libresolv library. If they are part of libc this wont work. This is
39 the case with glibc >= 2.34.
41 *RESOLV_WRAPPER_HOSTS*::
43 This environment variable is used for faking DNS queries. It must point to a
44 hosts-like text file that specifies fake records for custom queries. The
45 format of the file looks like this:
47 TYPE RECORD_NAME RECORD_VALUE
51 A dc.cwrap.org 127.0.0.10
52 AAAA dc.cwrap.org fd00::5357:5f0a
53 CNAME kerberos.cwrap.org dc.cwrap.org
54 SRV _kerberos._tcp.cwrap.org kerberos.cwrap.org 88
55 URI _vpn.cwrap.org https://vpn.cwrap.org/VPN
56 TXT cwrap.org v=spf1 mx
58 *RESOLV_WRAPPER_DEBUGLEVEL*::
60 If you need to see what is going on in resolv_wrapper itself or try to find a
61 bug, you can enable logging support in resolv_wrapper if you built it with
69 *RESOLV_WRAPPER_DISABLE_DEEPBIND*::
71 This allows you to disable deep binding in resolv_wrapper. This is useful for
72 running valgrind tools or sanitizers like (address, undefined, thread).
77 The following command would trick 'kinit(1)' into using DNS servers from "./resolv.conf"
78 for Kerberos service resolution:
80 $ LD_PRELOAD=libresolv_wrapper.so RESOLV_WRAPPER_CONF="./resolv.conf" kinit user@EXAMPLE.COM