.\" Id: idn.conf.5.in,v 1.1 2003/06/04 00:27:16 marka Exp "
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.TH idn.conf 5 "Mar 8, 2002"
.\"
.SH NAME
idn.conf, .idnrc, idnalias.conf \- configuration files for idnkit library
.\"
.SH SYNOPSIS
@sysconfdir@/idn.conf
.br
~/.idnrc
.br
@sysconfdir@/idnalias.conf
.\"
.SH DESCRIPTION
\fBidn.conf\fR and \fB.idnrc\fR are configuration files for idnkit
library which is a toolkit for handling internationalized domain names.
.PP
idnkit library tries to load the user's configuration file ~/.idnrc
first, and then tries the system configutation file 
@sysconfdir@/idn.conf.
Note that idnkit library loads either, not both.
.PP
To use internationalized domain names in DNS or other protocols, they
must be converted to an appropriate format before further processing.
In idnkit, this conversion process is comprised of the following tasks.
.IP 1. 3
Convert the given domain name in application's local codeset to Unicode,
and vice versa.
.IP 2. 3
Map certain characters in the name to period character so that they are
treated as the domain name
delimiter (\fIdelimiter mapping\fR).
.IP 3. 3
Map certain characters in the name to other characters or chracter sequences,
according to a mapping rule determined by its top level domain (TLD).
.IP 4. 3
Perform NAMEPREP, which is a starndard name preparation process for
internationalized domain names.  This process is composed of
the tree steps called mapping, normalization, prohibited character
checking and bidirectional string checking.
.IP 5. 3
Convert the nameprepped name to IDN encoding, which is the standard encoding
for internationalized domain names (also known as ASCII-compatible encoding,
ACE), and vice versa.
.PP
The configuration file specifies the parameters for these tasks, such as:
.RS 2
.IP \- 2
the encoding of internationalized domain names (IDN encoding).
.IP \- 2
NAMEPREP schemes.
.RE
.\"
.SH SYNTAX
The configuration file is a simple text files, and each line in the file
(other than comment lines, which begin with ``#'', and empty lines)
forms an entry of the following format:
.PP
.RS 4
.nf
\fIkeyword\fP\ \fIvalue..\fP
.fi
.RE
\."
.SH "IDN-ENCODING ENTRY"
IDN encoding entry specifies the encoding name (codeset name) which
is used as the encoding of internationalized domain names.
.PP
The syntax of this entry is:
.PP
.RS 4
.nf
\f(CWidn-encoding \fP\fIencoding\fP
.fi
.RE
.PP
\fIencoding\fP is the encoding name to be used, and any of the following
names can be specified.
.RS 2
.IP "\(bu" 2
``Punycode''
.IP "\(bu" 2
``UTF-8''
.IP "\(bu" 2
Codeset names which iconv_open() library function accepts.  Please
consult iconv() documentation for the available codesets.
.IP "\(bu" 2
Any alias names for the above, defined by the alias file.
(See section ``ENCODING-ALIAS-FILE'')
.RE
.PP
The standard encoding was determined as Punycode.
.\"
.SH "NAMEPREP ENTRY"
Nameprep entry specifies the version of NAMEPREP, which is a specification
of ``canonicalization'' process of internationalized domain name before
it is converted to the IDN encoding.
.PP
The syntax of this entry is:
.PP
.RS 4
.nf
\f(CWnameprep \fP\fIversion\fP
.fi
.RE
.PP
\fIversion\fR is the version name of NAMEPREP specification, and currently
the following versions can be specified.
.RS 2
.IP "\(bu" 2
``RFC3491''
.br
This version refers to RFC3491 ``rfc-3491.txt''.
.RE
.PP
The NAMEPREP process consists of the following 4 subprocesses.
.IP 1. 3
mapping, which maps certain characters in a name to other characters,
possibly none.
.IP 2. 3
normalization, which replaces character variants in a name to
a unique one.
.IP 3. 3
prohibited character checking, which detects invalid characters in a name.
.IP 4. 3
unassigned codepoint checking, which also invalid codepoints in a name.
.IP 5. 3
bidirectional string checking, which detecs invalid string.
.\"
.SH "LOCAL-MAP ENTRY"
This entry specifies localized mapping phase before NAMEPREP takes place.
Different mapping rules can be specified for each TLD (top-level domain).
For example, you can have one mapping for ``.tw'' domain, and another for
``.jp'' domain.
.PP
The syntax of this entry is:
.PP
.RS 4
.nf
\f(CWlocal-map \fItld\f(CW \fIscheme\fR [\fIscheme\fR..]
.fi
.RE
.PP
\fItld\fR specifies the TLD to which the mapping rule is to be applied,
and \fIscheme\fR specifies the mapping scheme, and currently available
schemes are:
.RS 2
.TP 4
\f(CWRFC3491\fP
Specify mapping defined by RFC3491.
.TP 4
\f(CWfilemap:\fP\fIpathname\fP
Specify mapping defined by the file \fIpathname\fP.
See ``MAPFILE FORMAT'' for the format of this file.
.RE
.PP
There are two special \fItld\fRs for specifying the mapping rule for
local domain names (domain names without any dots in them), and the
default mapping rule.
If
\fItld\fR is ``-'', it matches domain names which do not contain any
dots.
If \fItld\fR is ``.'', it matches any domain names which don't match
to any other mapping rules specified by ``local-map'' entries.
.\"
.SH "MAPFILE FORMAT"
A mapfile defines a set of character mapping rules.  It can define
unconditional one-character to N-character-sequence (N can be 0, 1 or more)
mappings.
.PP
A mapfile is a simple text file, and each line specifies a single mapping.
Each line is of the form:
.PP
.RS 4
.nf
\fIsrc-codepoint\fR\f(CW; \fImapped-codepoint-seq\fR\f(CW;\fR
.fi
.RE
.PP
\fIsrc-codepoint\fR indicates source character of the mapping, and must
be a Unicode codepoint value in hexadecimal string.
\fImapped-codepoint-seq\fR is a sequence of characters which is the
outcome of the mapping, and must be a (possibly empty) list of Unicode
codepoint values in hexadecimal string, separated by spaces.
.PP
Lines which begin with ``#'' are treated as comments and ignored.
.PP
A sample mapfile is shown below.
.PP
.RS 4
.nf
.ft CW
# map "A" to "a"
0041; 0061;
# map "#" to nothing
0023; ;
# map "@" to "at"
0040; 0061 0074;
.ft R
.fi
.RE
.\"
.SH "LOCAL CODESET"
\fBidn.conf\fR or \fB~/.idnrc\fR doesn't have an entry to specify the
local codeset, since it is determined from the application's current
locale information.
So each application can use different local codeset.
.PP
Although idnkit tries hard to find out the local codeset, sometimes it
fails.  For example, there are applications which use non-ASCII codeset
but work in C locale.  In this case, you can specify the application's
local codeset by an environment variable ``\fBIDN_LOCAL_CODESET\fR''.
Just set the codeset name (or its alias name) to the variable, and
idnkit will use the codeset as the local one, regardless of the locale
setting.
.\"
.SH "ENCODING-ALIAS-FILE"
Encoding alias file specifies codeset name aliases.  It is located on
@sysconfdir@/idnalias.conf and always loaded automatically as idn.conf
and .idnrc.  The aliases in this file can be used just as the real names.
.PP
The alias file is a simple text file, consisting of lines of the form:
.PP
.RS 4
.nf
\fIalias-name\fP\ \fIname\fP
.fi
.RE
.PP
\fIalias-name\fR is the alias name to be defined, and \fIname\fR is
the real name or another alias name.
.\"
.SH "SAMPLE CONFIGURATION"
The following shows a sample configuration file.
.PP
.RS 4
.ft CW
.nf
#
# a sample configuration.
#

# Use Punycode as the IDN encoding.
idn-encoding Punycode

# Use RFC3491 as NAMEPREP.
nameprep RFC3491

# Perform Japanese-specific mapping for .jp domain.
# assuming /usr/local/lib/idnkit/jp-map contains the mapping.
local-map .jp filemap:/usr/local/lib/idnkit/jp-map
.fi
.ft R
.RE
.\"
.SH FILES
.I @sysconfdir@/idn.conf
.br
.I ~/.idnrc
.br
.I @sysconfdir@/idnalias.conf
.br
.I @sysconfdir@/idn.conf.sample
\- sample configuration with comments
.br
.I @sysconfdir@/idnalias.conf.sample
\- sample alias file
.\"
.SH "SEE ALSO"
iconv(3)