'\" t
.\"     Title: resolv_wrapper
.\"    Author: The Samba Team
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 2020-01-31
.\"    Manual: \ \&
.\"    Source: \ \&
.\"  Language: English
.\"
.TH "RESOLV_WRAPPER" "1" "2020\-01\-31" "\ \&" "\ \&"
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.nh
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.SH "NAME"
resolv_wrapper \- A wrapper for dns name resolving or dns faking\&.
.SH "SYNOPSIS"
.sp
LD_PRELOAD=libresolv_wrapper\&.so RESOLV_WRAPPER_CONF="/path/to/resolv\&.conf" \fB\&./myapplication\fR
.SH "DESCRIPTION"
.sp
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\(cqt work on a special platform the wrapper is able to fake DNS queries and return valid responses to your application\&.
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Redirects name queries to the nameservers specified in your resolv\&.conf
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Can fake DNS queries using a simple formatted DNS hosts file\&.
.RE
.SH "ENVIRONMENT VARIABLES"
.PP
\fBRESOLV_WRAPPER_CONF\fR
.RS 4
This is used to specify the resolv\&.conf to use\&. The format of the resolv\&.conf file is defined in the manpage
\fIresolv\&.conf(5)\fR\&. Currently only the
\fBnamserver\fR
directive is supported\&.
.RE
.PP
\fBRESOLV_WRAPPER_HOSTS\fR
.RS 4
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:
.sp
.if n \{\
.RS 4
.\}
.nf
TYPE    RECORD_NAME RECORD_VALUE
.fi
.if n \{\
.RE
.\}
.RE
.sp
For example:
.sp
.if n \{\
.RS 4
.\}
.nf
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
.fi
.if n \{\
.RE
.\}
.PP
\fBRESOLV_WRAPPER_DEBUGLEVEL\fR
.RS 4
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\&.
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
0 = ERROR
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
1 = WARNING
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
2 = DEBUG
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
3 = TRACE
.RE
.RE
.PP
\fBRESOLV_WRAPPER_DISABLE_DEEPBIND\fR
.RS 4
This allows you to disable deep binding in resolv_wrapper\&. This is useful for running valgrind tools or sanitizers like (address, undefined, thread)\&.
.RE
.SH "EXAMPLE"
.sp
The following command would trick \fIkinit(1)\fR into using DNS servers from "\&./resolv\&.conf" for Kerberos service resolution:
.sp
.if n \{\
.RS 4
.\}
.nf
$ LD_PRELOAD=libresolv_wrapper\&.so RESOLV_WRAPPER_CONF="\&./resolv\&.conf" kinit user@EXAMPLE\&.COM
.fi
.if n \{\
.RE
.\}
.SH "AUTHOR"
.PP
\fBThe Samba Team\fR
.RS 4
Author.
.RE