File: libidn.info, Node: Top, Next: Introduction, Up: (dir)
GNU Libidn
**********
This manual is last updated 21 June 2017 for version 1.34 of GNU Libidn.
Copyright (C) 2002-2016 Simon Josefsson.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, no Front-Cover Texts, and
no Back-Cover Texts. A copy of the license is included in the
section entitled "GNU Free Documentation License".
* Menu:
* Introduction:: How to use this manual.
* Preparation:: What you should do before using the library.
* Utility Functions:: Unicode transformation utility functions.
* Stringprep Functions:: Stringprep functions.
* Punycode Functions:: Punycode functions.
* IDNA Functions:: IDNA functions.
* TLD Functions:: TLD functions.
* PR29 Functions:: Detect strings non-idempotent under NFKC.
* Examples:: Demonstrate how to use the library.
* Invoking idn:: Command line interface to the library.
* Emacs API:: Emacs Lisp API for Libidn.
* Java API:: Notes on the Java port of Libidn.
* C# API:: Notes on the C# port of Libidn.
* Acknowledgements:: Whom to blame.
* History:: Rough outline of development history.
Appendices
* PR29 discussion:: Implementation aspects of the PR29 flaw.
* On Label Separators:: Discussions of a flaw in the IDNA spec.
* Copying Information:: License texts.
Indices
* Function and Variable Index::
* Concept Index::
File: libidn.info, Node: Introduction, Next: Preparation, Prev: Top, Up: Top
1 Introduction
**************
GNU Libidn is a fully documented implementation of the Stringprep,
Punycode and IDNA specifications. Libidn's purpose is to encode and
decode internationalized domain name strings. There are native C, C#
and Java libraries.
The C library contains a generic Stringprep implementation. Profiles
for Nameprep, iSCSI, SASL, XMPP and Kerberos V5 are included. Punycode
and ASCII Compatible Encoding (ACE) via IDNA are supported. A mechanism
to define Top-Level Domain (TLD) specific validation tables, and to
compare strings against those tables, is included. Default tables for
some TLDs are also included.
The Stringprep API consists of two main functions, one for converting
data from the system's native representation into UTF-8, and one
function to perform the Stringprep processing. Adding a new Stringprep
profile for your application within the API is straightforward. The
Punycode API consists of one encoding function and one decoding
function. The IDNA API consists of the ToASCII and ToUnicode functions,
as well as an high-level interface for converting entire domain names to
and from the ACE encoded form. The TLD API consists of one set of
functions to extract the TLD name from a domain string, one set of
functions to locate the proper TLD table to use based on the TLD name,
and core functions to validate a string against a TLD table, and some
utility wrappers to perform all the steps in one call.
The library is used by, e.g., GNU SASL and Shishi to process user
names and passwords. Libidn can be built into GNU Libc to enable a new
system-wide getaddrinfo flag for IDN processing.
Libidn is developed for the GNU/Linux system, but runs on over 20
Unix platforms (including Solaris, IRIX, AIX, and Tru64) and Windows.
The library is written in C and (parts of) the API is also accessible
from C++, Emacs Lisp, Python and Java. A native Java and C# port is
included.
Also included is a command line tool, several self tests, code
examples, and more.
* Menu:
* Getting Started::
* Features::
* Library Overview::
* Supported Platforms::
* Getting help::
* Commercial Support::
* Downloading and Installing::
* Bug Reports::
* Contributing::
File: libidn.info, Node: Getting Started, Next: Features, Up: Introduction
1.1 Getting Started
===================
This manual documents the library programming interface. All functions
and data types provided by the library are explained. Included are also
examples, and documentation for the command line tool 'idn' that provide
a quick interface to the library. The Emacs Lisp bindings for the
library is also discussed.
The reader is assumed to possess basic familiarity with
internationalization concepts and network programming in C or C++.
This manual can be used in several ways. If read from the beginning
to the end, it gives a good introduction into the library and how it can
be used in an application. Forward references are included where
necessary. Later on, the manual can be used as a reference manual to
get just the information needed about any particular interface of the
library. Experienced programmers might want to start looking at the
examples at the end of the manual (*note Examples::), and then only read
up those parts of the interface which are unclear.
File: libidn.info, Node: Features, Next: Library Overview, Prev: Getting Started, Up: Introduction
1.2 Features
============
This library might have a couple of advantages over other libraries
doing a similar job.
It's Free Software
Anybody can use, modify, and redistribute it under the terms of a
free software license.
It's thread-safe
No global state is kept in the library. All functions are
re-entrant.
It's portable
The code is intended to be written in pure ANSI C89. It has been
tested on many Unix like operating systems, and Windows.
It's modularized
The library is composed of several modules, and the only
interaction between modules is through each modules' public API. If
you only need one piece of functionality, it is possible to take
the files you need and incorporate them into your own project.
It's not bloated
The design of the library is based on the smallest API necessary to
implement the basic functionality. It has been carefully extended
with a small number of high-level wrappers to make it comfortable
to use the library. However, it does not implement additional
functionality just for the sake of completeness.
It's documented
Sadly, not all software comes with documentation these days. This
one does.
File: libidn.info, Node: Library Overview, Next: Supported Platforms, Prev: Features, Up: Introduction
1.3 Library Overview
====================
The following illustration show the components that make up Libidn, and
how your application relates to the library. In the illustration,
various components are shown as boxes. You see the generic StringPrep
component, the various StringPrep profiles including Nameprep, the
Punycode component, the IDNA component, and the TLD component. The
arrows indicate aggregation, e.g., IDNA uses Punycode and Nameprep, and
in turn Nameprep uses the generic StringPrep interface. The interfaces
to all components are available for applications, no component within
the library is hidden from the application.
File: libidn.info, Node: Supported Platforms, Next: Getting help, Prev: Library Overview, Up: Introduction
1.4 Supported Platforms
=======================
Libidn has at some point in time been tested on the following platforms.
Build reports for each platforms and Libidn version is available at
<http://autobuild.josefsson.org/libidn/>;.
1. Debian GNU/Linux 3.0 (Woody)
GCC 2.95.4 and GNU Make. This is the main development platform.
'alphaev67-unknown-linux-gnu', 'alphaev6-unknown-linux-gnu',
'arm-unknown-linux-gnu', 'armv4l-unknown-linux-gnu',
'hppa-unknown-linux-gnu', 'hppa64-unknown-linux-gnu',
'i686-pc-linux-gnu', 'ia64-unknown-linux-gnu',
'm68k-unknown-linux-gnu', 'mips-unknown-linux-gnu',
'mipsel-unknown-linux-gnu', 'powerpc-unknown-linux-gnu',
's390-ibm-linux-gnu', 'sparc-unknown-linux-gnu',
'sparc64-unknown-linux-gnu'.
2. Debian GNU/Linux 2.1
GCC 2.95.1 and GNU Make. 'armv4l-unknown-linux-gnu'.
3. Tru64 UNIX
Tru64 UNIX C compiler and Tru64 Make. 'alphaev67-dec-osf5.1',
'alphaev68-dec-osf5.1'.
4. SuSE Linux 7.1
GCC 2.96 and GNU Make. 'alphaev6-unknown-linux-gnu',
'alphaev67-unknown-linux-gnu'.
5. SuSE Linux 7.2a
GCC 3.0 and GNU Make. 'ia64-unknown-linux-gnu'.
6. SuSE Linux
GCC 3.2.2 and GNU Make. 'x86_64-unknown-linux-gnu' (AMD64 Opteron
"Melody").
7. SuSE Enterprise Server 9 on IBM OpenPower 720
GCC 3.3.3 and GNU Make. 'powerpc64-unknown-linux-gnu'.
8. RedHat Linux 7.2
GCC 2.96 and GNU Make. 'alphaev6-unknown-linux-gnu',
'alphaev67-unknown-linux-gnu', 'ia64-unknown-linux-gnu'.
9. RedHat Linux 8.0
GCC 3.2 and GNU Make. 'i686-pc-linux-gnu'.
10. RedHat Advanced Server 2.1
GCC 2.96 and GNU Make. 'i686-pc-linux-gnu'.
11. Slackware Linux 8.0.01
GCC 2.95.3 and GNU Make. 'i686-pc-linux-gnu'.
12. Mandrake Linux 9.0
GCC 3.2 and GNU Make. 'i686-pc-linux-gnu'.
13. IRIX 6.5
MIPS C compiler, IRIX Make. 'mips-sgi-irix6.5'.
14. AIX 4.3.2
IBM C for AIX compiler, AIX Make. 'rs6000-ibm-aix4.3.2.0'.
15. Microsoft Windows 2000 (Cygwin)
GCC 3.2, GNU make. 'i686-pc-cygwin'.
16. HP-UX 11
HP-UX C compiler and HP Make. 'ia64-hp-hpux11.22',
'hppa2.0w-hp-hpux11.11'.
17. SUN Solaris 2.7
GCC 3.0.4 and GNU Make. 'sparc-sun-solaris2.7'.
18. SUN Solaris 2.8
Sun WorkShop Compiler C 6.0 and SUN Make. 'sparc-sun-solaris2.8'.
19. SUN Solaris 2.9
Sun Forte Developer 7 C compiler and GNU Make.
'sparc-sun-solaris2.9'.
20. NetBSD 1.6
GCC 2.95.3 and GNU Make. 'alpha-unknown-netbsd1.6',
'i386-unknown-netbsdelf1.6'.
21. OpenBSD 3.1 and 3.2
GCC 2.95.3 and GNU Make. 'alpha-unknown-openbsd3.1',
'i386-unknown-openbsd3.1'.
22. FreeBSD 4.7 and 4.8
GCC 2.95.4 and GNU Make. 'alpha-unknown-freebsd4.7',
'alpha-unknown-freebsd4.8', 'i386-unknown-freebsd4.7',
'i386-unknown-freebsd4.8'.
23. MacOS X 10.2 Server Edition
GCC 3.1 and GNU Make. 'powerpc-apple-darwin6.5'.
24. MacOS X 10.4 "Tiger" with Xcode 2.0
GCC 4.0 and GNU Make. 'powerpc-apple-darwin8.0'.
25. Cross compiled to uClinux/uClibc on Motorola Coldfire
GCC 3.4 and GNU Make 'm68k-uclinux-elf'.
26. Cross compiled to ARM using Glibc
GCC 2.95 and GNU Make 'arm-linux'.
27. Cross compiled to Mingw32.
GCC 3.4.4 and GNU Make 'i586-mingw32msvc'.
28. OS/2
GCC.
If you use Libidn on, or port Libidn to, a new platform please report
it to the author.
File: libidn.info, Node: Getting help, Next: Commercial Support, Prev: Supported Platforms, Up: Introduction
1.5 Getting help
================
A mailing list where users of Libidn may help each other exists, and you
can reach it by sending e-mail to <help-libidn AT gnu.org>. Archives of
the mailing list discussions, and an interface to manage subscriptions,
is available through the World Wide Web at
<http://lists.gnu.org/mailman/listinfo/help-libidn>;.
File: libidn.info, Node: Commercial Support, Next: Downloading and Installing, Prev: Getting help, Up: Introduction
1.6 Commercial Support
======================
Commercial support is available for users of GNU Libidn. The kind of
support that can be purchased may include:
* Implement new features. Such as country code specific profiling to
support a restricted subset of Unicode.
* Port Libidn to new platforms. This could include porting Libidn to
an embedded platforms that may need memory or size optimization.
* Integrating IDN support in your existing project.
* System design of components related to IDN.
If you are interested, please write to:
Simon Josefsson Datakonsult AB
Hagagatan 24
113 47 Stockholm
Sweden
E-mail: simon AT josefsson.org
If your company provides support related to GNU Libidn and would like
to be mentioned here, contact the author (*note Bug Reports::).
File: libidn.info, Node: Downloading and Installing, Next: Bug Reports, Prev: Commercial Support, Up: Introduction
1.7 Downloading and Installing
==============================
The package can be downloaded from several places, including:
<ftp://alpha.gnu.org/pub/gnu/libidn/>;
The latest version is stored in a file, e.g., 'libidn-1.34.tar.gz'
where the '1.34' value is the highest version number in the directory.
The package is then extracted, configured and built like many other
packages that use Autoconf. For detailed information on configuring and
building it, refer to the 'INSTALL' file that is part of the
distribution archive.
Here is an example terminal session that download, configure, build
and install the package. You will need a few basic tools, such as 'sh',
'make' and 'cc'.
$ wget -q ftp://alpha.gnu.org/pub/gnu/libidn/libidn-1.34.tar.gz
$ tar xfz libidn-1.34.tar.gz
$ cd libidn-1.34/
$ ./configure
...
$ make
...
$ make install
...
After that Libidn should be properly installed and ready for use.
A few 'configure' options may be relevant, summarized in the table.
'--enable-java'
Build the Java port into a *.JAR file. *Note Java API::, for more
information.
'--disable-tld'
Disable the TLD module. This would typically only be useful if you
are building on a memory restricted platforms. *Note TLD
Functions::, for more information.
'--enable-csharp[=IMPL]'
Build the 'C#' port into a '*.DLL' file. *Note C# API::, for more
information. Here, 'IMPL' is 'pnet' or 'mono', indicating whether
the PNET 'cscc' compiler or the Mono 'mcs' compiler should be used,
respectively.
'--disable-valgrind-tests'
Disable running the self-checks under Valgrind
(<http://valgrind.org/>;). Normally Valgrind does not cause
problems and can detect some severe memory errors. If you are
getting errors from Valgrind that are caused by the compiler or
libc (possibly as a result of special optimization flags), you may
use this option to disable the use of Valgrind.
For the complete list, refer to the output from 'configure --help'.
* Menu:
* Installing under Windows:: Windows specific build instructions.
File: libidn.info, Node: Installing under Windows, Up: Downloading and Installing
1.7.1 Installing under Windows
------------------------------
There are two ways to build Libidn on Windows: via MinGW or via Visual
Studio.
With MinGW, you can build a Libidn DLL and use it from other
applications. After installing MinGW (<http://mingw.org/>;) follow the
generic installation instructions (*note Downloading and Installing::).
The DLL is installed by default.
For information on how to use the DLL in other applications, see:
<http://www.mingw.org/mingwfaq.shtml#faq-msvcdll>;.
You can build Libidn as a native Visual Studio C++ project. This
allows you to build the code for other platforms that VS supports, such
as Windows Mobile. You need Visual Studio 2005 or later.
First download and unpack the archive as described in the generic
installation instructions (*note Downloading and Installing::). Don't
run './configure'. Instead, start Visual Studio and open the project
file 'windows/libidn.sln' inside the Libidn directory. You should be
able to build the project using Build Project.
Output libraries will be written into the 'windows/lib' (or
'windows/lib/debug' for Debug versions) folder.
When working with Windows you may want to look into the special
memory handling functions that may be needed (*note Memory handling
under Windows::).
File: libidn.info, Node: Bug Reports, Next: Contributing, Prev: Downloading and Installing, Up: Introduction
1.8 Bug Reports
===============
If you think you have found a bug in Libidn, please investigate it and
report it.
* Please make sure that the bug is really in Libidn, and preferably
also check that it hasn't already been fixed in the latest version.
* You have to send us a test case that makes it possible for us to
reproduce the bug.
* You also have to explain what is wrong; if you get a crash, or if
the results printed are not good and in that case, in what way.
Make sure that the bug report includes all information you would
need to fix this kind of bug for someone else.
Please make an effort to produce a self-contained report, with
something definite that can be tested or debugged. Vague queries or
piecemeal messages are difficult to act on and don't help the
development effort.
If your bug report is good, we will do our best to help you to get a
corrected version of the software; if the bug report is poor, we won't
do anything about it (apart from asking you to send better bug reports).
If you think something in this manual is unclear, or downright
incorrect, or if the language needs to be improved, please also send a
note.
Send your bug report to:
'bug-libidn AT gnu.org'
File: libidn.info, Node: Contributing, Prev: Bug Reports, Up: Introduction
1.9 Contributing
================
If you want to submit a patch for inclusion - from solve a typo you
discovered, up to adding support for a new feature - you should submit
it as a bug report (*note Bug Reports::). There are some things that
you can do to increase the chances for it to be included in the official
package.
Unless your patch is very small (say, under 10 lines) we require that
you assign the copyright of your work to the Free Software Foundation.
This is to protect the freedom of the project. If you have not already
signed papers, we will send you the necessary information when you
submit your contribution.
For contributions that doesn't consist of actual programming code,
the only guidelines are common sense. Use it.
For code contributions, a number of style guides will help you:
* Coding Style. Follow the GNU Standards document (*note GNU Coding
Standards: (standards)top.).
If you normally code using another coding standard, there is no
problem, but you should use 'indent' to reformat the code (*note
GNU Indent: (indent)top.) before submitting your work.
* Use the unified diff format 'diff -u'.
* Return errors. No reason whatsoever should abort the execution of
the library. Even memory allocation errors, e.g. when malloc
return NULL, should work although result in an error code.
* Design with thread safety in mind. Don't use global variables and
the like.
* Avoid using the C math library. It causes problems for embedded
implementations, and in most situations it is very easy to avoid
using it.
* Document your functions. Use comments before each function
headers, that, if properly formatted, are extracted into GTK-DOC
web pages. Don't forget to update the Texinfo manual as well.
* Supply a ChangeLog and NEWS entries, where appropriate.
File: libidn.info, Node: Preparation, Next: Utility Functions, Prev: Introduction, Up: Top
2 Preparation
*************
To use 'Libidn', you have to perform some changes to your sources and
the build system. The necessary changes are small and explained in the
following sections. At the end of this chapter, it is described how the
library is initialized, and how the requirements of the library are
verified.
A faster way to find out how to adapt your application for use with
'Libidn' may be to look at the examples at the end of this manual (*note
Examples::).
* Menu:
* Header::
* Initialization::
* Version Check::
* Building the source::
* Autoconf tests::
* Memory handling under Windows::
File: libidn.info, Node: Header, Next: Initialization, Up: Preparation
2.1 Header
==========
The library contains a few independent parts, and each part export the
interfaces (data types and functions) in a header file. You must
include the appropriate header files in all programs using the library,
either directly or through some other header file, like this:
#include <stringprep.h>
The header files and the functions they define are categorized as
follows:
stringprep.h
The low-level stringprep API entry point. For IDN applications,
this is usually invoked via IDNA. Some applications, specifically
non-IDN ones, may want to prepare strings directly though, and
should include this header file.
The name space of the stringprep part of Libidn is 'stringprep*'
for function names, 'Stringprep*' for data types and 'STRINGPREP_*'
for other symbols. In addition, '_stringprep*' is reserved for
internal use and should never be used by applications.
punycode.h
The entry point to Punycode encoding and decoding functions.
Normally punycode is used via the idna.h interface, but some
application may want to perform raw punycode operations.
The name space of the punycode part of Libidn is 'punycode_*' for
function names, 'Punycode*' for data types and 'PUNYCODE_*' for
other symbols. In addition, '_punycode*' is reserved for internal
use and should never be used by applications.
idna.h
The entry point to the IDNA functions. This is the normal entry
point for applications that need IDN functionality.
The name space of the IDNA part of Libidn is 'idna_*' for function
names, 'Idna*' for data types and 'IDNA_*' for other symbols. In
addition, '_idna*' is reserved for internal use and should never be
used by applications.
tld.h
The entry point to the TLD functions. Normal applications are not
expected to need this functionality, but it is present for
applications that are used by TLDs to validate customer input.
The name space of the TLD part of Libidn is 'tld_*' for function
names, 'Tld_*' for data types and 'TLD_*' for other symbols. In
addition, '_tld*' is reserved for internal use and should never be
used by applications.
pr29.h
The entry point to the PR29 functions. These functions are used to
detect "problem sequences" (*note PR29 Functions::), mostly for use
in security critical applications.
The name space of the PR29 part of Libidn is 'pr29_*' for function
names, 'Pr29_*' for data types and 'PR29_*' for other symbols. In
addition, '_pr29*' is reserved for internal use and should never be
used by applications.
idn-free.h
The entry point to the Windows memory de-allocation function (*note
Memory handling under Windows::). It contains only one function
'idn_free'.
All header files defined and use the symbol 'IDNAPI' to decorate the
API functions.
File: libidn.info, Node: Initialization, Next: Version Check, Prev: Header, Up: Preparation
2.2 Initialization
==================
Libidn is stateless and does not need any initialization.
File: libidn.info, Node: Version Check, Next: Building the source, Prev: Initialization, Up: Preparation
2.3 Version Check
=================
It is often desirable to check that the version of 'Libidn' used is
indeed one which fits all requirements. Even with binary compatibility
new features may have been introduced but due to problem with the
dynamic linker an old version is actually used. So you may want to
check that the version is okay right after program startup.
stringprep_check_version
------------------------
-- Function: const char * stringprep_check_version (const char *
REQ_VERSION)
REQ_VERSION: Required version number, or NULL.
Check that the version of the library is at minimum the requested
one and return the version string; return NULL if the condition is
not satisfied. If a NULL is passed to this function, no check is
done, but the version string is simply returned.
See 'STRINGPREP_VERSION' for a suitable 'req_version' string.
Return value: Version string of run-time library, or NULL if the
run-time library does not meet the required version number.
The normal way to use the function is to put something similar to the
following first in your 'main':
if (!stringprep_check_version (STRINGPREP_VERSION))
{
printf ("stringprep_check_version() failed:\n"
"Header file incompatible with shared library.\n");
exit(EXIT_FAILURE);
}
File: libidn.info, Node: Building the source, Next: Autoconf tests, Prev: Version Check, Up: Preparation
2.4 Building the source
=======================
If you want to compile a source file including e.g. the 'idna.h' header
file, you must make sure that the compiler can find it in the directory
hierarchy. This is accomplished by adding the path to the directory in
which the header file is located to the compilers include file search
path (via the '-I' option).
However, the path to the include file is determined at the time the
source is configured. To solve this problem, 'Libidn' uses the external
package 'pkg-config' that knows the path to the include file and other
configuration options. The options that need to be added to the
compiler invocation at compile time are output by the '--cflags' option
to 'pkg-config libidn'. The following example shows how it can be used
at the command line:
gcc -c foo.c `pkg-config libidn --cflags`
Adding the output of 'pkg-config libidn --cflags' to the compilers
command line will ensure that the compiler can find e.g. the idna.h
header file.
A similar problem occurs when linking the program with the library.
Again, the compiler has to find the library files. For this to work,
the path to the library files has to be added to the library search path
(via the '-L' option). For this, the option '--libs' to 'pkg-config
libidn' can be used. For convenience, this option also outputs all
other options that are required to link the program with the 'libidn'
library. The example shows how to link 'foo.o' with the 'libidn'
library to a program 'foo'.
gcc -o foo foo.o `pkg-config libidn --libs`
Of course you can also combine both examples to a single command by
specifying both options to 'pkg-config':
gcc -o foo foo.c `pkg-config libidn --cflags --libs`
File: libidn.info, Node: Autoconf tests, Next: Memory handling under Windows, Prev: Building the source, Up: Preparation
2.5 Autoconf tests
==================
If your project uses Autoconf (*note GNU Autoconf: (autoconf)top.) to
check for installed libraries, you might find the following snippet
illustrative. It add a new 'configure' parameter '--with-libidn', and
check for 'idna.h' and '-lidn' (possibly below the directory specified
as the optional argument to '--with-libidn'), and define the CPP symbol
'LIBIDN' if the library is found. The default behaviour is to search
for the library and enable the functionality (that is, define the
symbol) when the library is found, but if you wish to make the default
behaviour of your package be that Libidn is not used (even if it is
installed on the system), change 'libidn=yes' to 'libidn=no' on the
third line.
AC_ARG_WITH(libidn, AC_HELP_STRING([--with-libidn=[DIR]],
[Support IDN (needs GNU Libidn)]),
libidn=$withval, libidn=yes)
if test "$libidn" != "no"; then
if test "$libidn" != "yes"; then
LDFLAGS="${LDFLAGS} -L$libidn/lib"
CPPFLAGS="${CPPFLAGS} -I$libidn/include"
fi
AC_CHECK_HEADER(idna.h,
AC_CHECK_LIB(idn, stringprep_check_version,
[libidn=yes LIBS="${LIBS} -lidn"], libidn=no),
libidn=no)
fi
if test "$libidn" != "no" ; then
AC_DEFINE(LIBIDN, 1, [Define to 1 if you want IDN support.])
else
AC_MSG_WARN([Libidn not found])
fi
AC_MSG_CHECKING([if Libidn should be used])
AC_MSG_RESULT($libidn)
If you require that your users have installed 'pkg-config' (which I
cannot recommend generally), the above can be done more easily as
follows.
AC_ARG_WITH(libidn, AC_HELP_STRING([--with-libidn=[DIR]],
[Support IDN (needs GNU Libidn)]),
libidn=$withval, libidn=yes)
if test "$libidn" != "no" ; then
PKG_CHECK_MODULES(LIBIDN, libidn >= 0.0.0, [libidn=yes], [libidn=no])
if test "$libidn" != "yes" ; then
libidn=no
AC_MSG_WARN([Libidn not found])
else
libidn=yes
AC_DEFINE(LIBIDN, 1, [Define to 1 if you want Libidn.])
fi
fi
AC_MSG_CHECKING([if Libidn should be used])
AC_MSG_RESULT($libidn)
File: libidn.info, Node: Memory handling under Windows, Prev: Autoconf tests, Up: Preparation
2.6 Memory handling under Windows
=================================
Several functions in the library allocates memory. The memory is
expected to be de-allocated using the 'free' function. Under Windows,
it is sometimes necessary to de-allocate memory in the same module that
allocated a memory region. The reason is that different modules use
separate heap memory regions. To solve this problem we provide a
function to de-allocate memory inside the library.
Note that we do not recommend using this interface generally if you
do not care about Windows portability.
2.7 Header file 'idn-free.h'
============================
To use the function explained in this chapter, you need to include the
file 'idn-free.h' using:
#include <idn-free.h>
2.8 Memory de-allocation function
=================================
idn_free
--------
-- Function: void idn_free (void * PTR)
PTR: memory region to deallocate, or 'NULL' .
Deallocates memory region by calling 'free()' . If 'ptr' is 'NULL'
no operation is performed.
Normally applications de-allocate strings allocated by libidn by
calling 'free()' directly. Under Windows, different parts of the
same application may use different heap memory, and then it is
important to deallocate memory allocated within the same module
that allocated it. This function makes that possible.
File: libidn.info, Node: Utility Functions, Next: Stringprep Functions, Prev: Preparation, Up: Top
3 Utility Functions
*******************
The rest of this library makes extensive use of Unicode characters. In
order to interface this library with the outside world, your application
may need to make various Unicode transformations.
3.1 Header file 'stringprep.h'
==============================
To use the functions explained in this chapter, you need to include the
file 'stringprep.h' using:
#include <stringprep.h>
3.2 Unicode Encoding Transformation
===================================
stringprep_unichar_to_utf8
--------------------------
-- Function: int stringprep_unichar_to_utf8 (uint32_t C, char * OUTBUF)
C: a ISO10646 character code
OUTBUF: output buffer, must have at least 6 bytes of space. If
'NULL' , the length will be computed and returned and nothing will
be written to 'outbuf' .
Converts a single character to UTF-8.
Return value: number of bytes written.
stringprep_utf8_to_unichar
--------------------------
-- Function: uint32_t stringprep_utf8_to_unichar (const char * P)
P: a pointer to Unicode character encoded as UTF-8
Converts a sequence of bytes encoded as UTF-8 to a Unicode
character. If 'p' does not point to a valid UTF-8 encoded
character, results are undefined.
Return value: the resulting character.
stringprep_ucs4_to_utf8
-----------------------
-- Function: char * stringprep_ucs4_to_utf8 (const uint32_t * STR,
ssize_t LEN, size_t * ITEMS_READ, size_t * ITEMS_WRITTEN)
STR: a UCS-4 encoded string
LEN: the maximum length of 'str' to use. If 'len' < 0, then the
string is terminated with a 0 character.
ITEMS_READ: location to store number of characters read read, or
'NULL' .
ITEMS_WRITTEN: location to store number of bytes written or 'NULL'
. The value here stored does not include the trailing 0 byte.
Convert a string from a 32-bit fixed width representation as UCS-4.
to UTF-8. The result will be terminated with a 0 byte.
Return value: a pointer to a newly allocated UTF-8 string. This
value must be deallocated by the caller. If an error occurs,
'NULL' will be returned.
stringprep_utf8_to_ucs4
-----------------------
-- Function: uint32_t * stringprep_utf8_to_ucs4 (const char * STR,
ssize_t LEN, size_t * ITEMS_WRITTEN)
STR: a UTF-8 encoded string
LEN: the maximum length of 'str' to use. If 'len' < 0, then the
string is nul-terminated.
ITEMS_WRITTEN: location to store the number of characters in the
result, or 'NULL' .
Convert a string from UTF-8 to a 32-bit fixed width representation
as UCS-4. The function now performs error checking to verify that
the input is valid UTF-8 (before it was documented to not do error
checking).
Return value: a pointer to a newly allocated UCS-4 string. This
value must be deallocated by the caller.
3.3 Unicode Normalization
=========================
stringprep_ucs4_nfkc_normalize
------------------------------
-- Function: uint32_t * stringprep_ucs4_nfkc_normalize (const uint32_t
* STR, ssize_t LEN)
STR: a Unicode string.
LEN: length of 'str' array, or -1 if 'str' is nul-terminated.
Converts a UCS4 string into canonical form, see
'stringprep_utf8_nfkc_normalize()' for more information.
Return value: a newly allocated Unicode string, that is the NFKC
normalized form of 'str' .
stringprep_utf8_nfkc_normalize
------------------------------
-- Function: char * stringprep_utf8_nfkc_normalize (const char * STR,
ssize_t LEN)
STR: a UTF-8 encoded string.
LEN: length of 'str' , in bytes, or -1 if 'str' is nul-terminated.
Converts a string into canonical form, standardizing such issues as
whether a character with an accent is represented as a base
character and combining accent or as a single precomposed
character.
The normalization mode is NFKC (ALL COMPOSE). It standardizes
differences that do not affect the text content, such as the
above-mentioned accent representation. It standardizes the
"compatibility" characters in Unicode, such as SUPERSCRIPT THREE to
the standard forms (in this case DIGIT THREE). Formatting
information may be lost but for most text operations such
characters should be considered the same. It returns a result with
composed forms rather than a maximally decomposed form.
Return value: a newly allocated string, that is the NFKC normalized
form of 'str' .
3.4 Character Set Conversion
============================
stringprep_locale_charset
-------------------------
-- Function: const char * stringprep_locale_charset ( VOID)
Find out current locale charset. The function respect the CHARSET
environment variable, but typically uses nl_langinfo(CODESET) when
it is supported. It fall back on "ASCII" if CHARSET isn't set and
nl_langinfo isn't supported or return anything.
Note that this function return the application's locale's preferred
charset (or thread's locale's preffered charset, if your system
support thread-specific locales). It does not return what the
system may be using. Thus, if you receive data from external
sources you cannot in general use this function to guess what
charset it is encoded in. Use stringprep_convert from the external
representation into the charset returned by this function, to have
data in the locale encoding.
Return value: Return the character set used by the current locale.
It will never return NULL, but use "ASCII" as a fallback.
stringprep_convert
------------------
-- Function: char * stringprep_convert (const char * STR, const char *
TO_CODESET, const char * FROM_CODESET)
STR: input zero-terminated string.
TO_CODESET: name of destination character set.
FROM_CODESET: name of origin character set, as used by 'str' .
Convert the string from one character set to another using the
system's 'iconv()' function.
Return value: Returns newly allocated zero-terminated string which
is 'str' transcoded into to_codeset.
stringprep_locale_to_utf8
-------------------------
-- Function: char * stringprep_locale_to_utf8 (const char * STR)
STR: input zero terminated string.
Convert string encoded in the locale's character set into UTF-8 by
using 'stringprep_convert()' .
Return value: Returns newly allocated zero-terminated string which
is 'str' transcoded into UTF-8.
stringprep_utf8_to_locale
-------------------------
-- Function: char * stringprep_utf8_to_locale (const char * STR)
STR: input zero terminated string.
Convert string encoded in UTF-8 into the locale's character set by
using 'stringprep_convert()' .
Return value: Returns newly allocated zero-terminated string which
is 'str' transcoded into the locale's character set.
File: libidn.info, Node: Stringprep Functions, Next: Punycode Functions, Prev: Utility Functions, Up: Top
4 Stringprep Functions
**********************
Stringprep describes a framework for preparing Unicode text strings in
order to increase the likelihood that string input and string comparison
work in ways that make sense for typical users throughout the world.
The stringprep protocol is useful for protocol identifier values,
company and personal names, internationalized domain names, and other
text strings.
4.1 Header file 'stringprep.h'
==============================
To use the functions explained in this chapter, you need to include the
file 'stringprep.h' using:
#include <stringprep.h>
4.2 Defining A Stringprep Profile
=================================
Further types and structures are defined for applications that want to
specify their own stringprep profile. As these are fairly obscure, and
by necessity tied to the implementation, we do not document them here.
Look into the 'stringprep.h' header file, and the 'profiles.c' source
code for the details.
4.3 Control Flags
=================
-- Stringprep flags: Stringprep_profile_flags STRINGPREP_NO_NFKC
Disable the NFKC normalization, as well as selecting the non-NFKC
case folding tables. Usually the profile specifies BIDI and NFKC
settings, and applications should not override it unless in special
situations.
-- Stringprep flags: Stringprep_profile_flags STRINGPREP_NO_BIDI
Disable the BIDI step. Usually the profile specifies BIDI and NFKC
settings, and applications should not override it unless in special
situations.
-- Stringprep flags: Stringprep_profile_flags STRINGPREP_NO_UNASSIGNED
Make the library return with an error if string contains unassigned
characters according to profile.
4.4 Core Functions
==================
stringprep_4i
-------------
-- Function: int stringprep_4i (uint32_t * UCS4, size_t * LEN, size_t
MAXUCS4LEN, Stringprep_profile_flags FLAGS, const
Stringprep_profile * PROFILE)
UCS4: input/output array with string to prepare.
LEN: on input, length of input array with Unicode code points, on
exit, length of output array with Unicode code points.
MAXUCS4LEN: maximum length of input/output array.
FLAGS: a 'Stringprep_profile_flags' value, or 0.
PROFILE: pointer to 'Stringprep_profile' to use.
Prepare the input UCS-4 string according to the stringprep profile,
and write back the result to the input string.
The input is not required to be zero terminated ( 'ucs4' [ 'len' ]
= 0). The output will not be zero terminated unless 'ucs4' [ 'len'
] = 0. Instead, see 'stringprep_4zi()' if your input is zero
terminated or if you want the output to be.
Since the stringprep operation can expand the string, 'maxucs4len'
indicate how large the buffer holding the string is. This function
will not read or write to code points outside that size.
The 'flags' are one of 'Stringprep_profile_flags' values, or 0.
The 'profile' contain the 'Stringprep_profile' instructions to
perform. Your application can define new profiles, possibly
re-using the generic stringprep tables that always will be part of
the library, or use one of the currently supported profiles.
Return value: Returns 'STRINGPREP_OK' iff successful, or an
'Stringprep_rc' error code.
stringprep_4zi
--------------
-- Function: int stringprep_4zi (uint32_t * UCS4, size_t MAXUCS4LEN,
Stringprep_profile_flags FLAGS, const Stringprep_profile *
PROFILE)
UCS4: input/output array with zero terminated string to prepare.
MAXUCS4LEN: maximum length of input/output array.
FLAGS: a 'Stringprep_profile_flags' value, or 0.
PROFILE: pointer to 'Stringprep_profile' to use.
Prepare the input zero terminated UCS-4 string according to the
stringprep profile, and write back the result to the input string.
Since the stringprep operation can expand the string, 'maxucs4len'
indicate how large the buffer holding the string is. This function
will not read or write to code points outside that size.
The 'flags' are one of 'Stringprep_profile_flags' values, or 0.
The 'profile' contain the 'Stringprep_profile' instructions to
perform. Your application can define new profiles, possibly
re-using the generic stringprep tables that always will be part of
the library, or use one of the currently supported profiles.
Return value: Returns 'STRINGPREP_OK' iff successful, or an
'Stringprep_rc' error code.
stringprep
----------
-- Function: int stringprep (char * IN, size_t MAXLEN,
Stringprep_profile_flags FLAGS, const Stringprep_profile *
PROFILE)
IN: input/ouput array with string to prepare.
MAXLEN: maximum length of input/output array.
FLAGS: a 'Stringprep_profile_flags' value, or 0.
PROFILE: pointer to 'Stringprep_profile' to use.
Prepare the input zero terminated UTF-8 string according to the
stringprep profile, and write back the result to the input string.
Note that you must convert strings entered in the systems locale
into UTF-8 before using this function, see
'stringprep_locale_to_utf8()' .
Since the stringprep operation can expand the string, 'maxlen'
indicate how large the buffer holding the string is. This function
will not read or write to characters outside that size.
The 'flags' are one of 'Stringprep_profile_flags' values, or 0.
The 'profile' contain the 'Stringprep_profile' instructions to
perform. Your application can define new profiles, possibly
re-using the generic stringprep tables that always will be part of
the library, or use one of the currently supported profiles.
Return value: Returns 'STRINGPREP_OK' iff successful, or an error
code.
stringprep_profile
------------------
-- Function: int stringprep_profile (const char * IN, char ** OUT,
const char * PROFILE, Stringprep_profile_flags FLAGS)
IN: input array with UTF-8 string to prepare.
OUT: output variable with pointer to newly allocate string.
PROFILE: name of stringprep profile to use.
FLAGS: a 'Stringprep_profile_flags' value, or 0.
Prepare the input zero terminated UTF-8 string according to the
stringprep profile, and return the result in a newly allocated
variable.
Note that you must convert strings entered in the systems locale
into UTF-8 before using this function, see
'stringprep_locale_to_utf8()' .
The output 'out' variable must be deallocated by the caller.
The 'flags' are one of 'Stringprep_profile_flags' values, or 0.
The 'profile' specifies the name of the stringprep profile to use.
It must be one of the internally supported stringprep profiles.
Return value: Returns 'STRINGPREP_OK' iff successful, or an error
code.
4.5 Error Handling
==================
stringprep_strerror
-------------------
-- Function: const char * stringprep_strerror (Stringprep_rc RC)
RC: a 'Stringprep_rc' return code.
Convert a return code integer to a text string. This string can be
used to output a diagnostic message to the user.
*STRINGPREP_OK:* Successful operation. This value is guaranteed to
always be zero, the remaining ones are only guaranteed to hold
non-zero values, for logical comparison purposes.
*STRINGPREP_CONTAINS_UNASSIGNED:* String contain unassigned Unicode
code points, which is forbidden by the profile.
*STRINGPREP_CONTAINS_PROHIBITED:* String contain code points
prohibited by the profile.
*STRINGPREP_BIDI_BOTH_L_AND_RAL:* String contain code points with
conflicting bidirection category.
*STRINGPREP_BIDI_LEADTRAIL_NOT_RAL:* Leading and trailing character
in string not of proper bidirectional category.
*STRINGPREP_BIDI_CONTAINS_PROHIBITED:* Contains prohibited code
points detected by bidirectional code.
*STRINGPREP_TOO_SMALL_BUFFER:* Buffer handed to function was too
small. This usually indicate a problem in the calling application.
*STRINGPREP_PROFILE_ERROR:* The stringprep profile was
inconsistent. This usually indicate an internal error in the
library.
*STRINGPREP_FLAG_ERROR:* The supplied flag conflicted with profile.
This usually indicate a problem in the calling application.
*STRINGPREP_UNKNOWN_PROFILE:* The supplied profile name was not
known to the library.
*STRINGPREP_ICONV_ERROR:* Could not convert string in locale
encoding.
*STRINGPREP_NFKC_FAILED:* The Unicode NFKC operation failed. This
usually indicate an internal error in the library.
*STRINGPREP_MALLOC_ERROR:* The 'malloc()' was out of memory. This
is usually a fatal error.
Return value: Returns a pointer to a statically allocated string
containing a description of the error with the return code 'rc' .
4.6 Stringprep Profile Macros
=============================
-- Function: int stringprep_nameprep_no_unassigned (char * IN, int
MAXLEN)
IN: input/ouput array with string to prepare.
MAXLEN: maximum length of input/output array.
Prepare the input UTF-8 string according to the nameprep profile.
The AllowUnassigned flag is false, use 'stringprep_nameprep' for
true AllowUnassigned. Returns 0 iff successful, or an error code.
-- Function: int stringprep_iscsi (char * IN, int MAXLEN)
IN: input/ouput array with string to prepare.
MAXLEN: maximum length of input/output array.
Prepare the input UTF-8 string according to the draft iSCSI
stringprep profile. Returns 0 iff successful, or an error code.
-- Function: int stringprep_plain (char * IN, int MAXLEN)
IN: input/ouput array with string to prepare.
MAXLEN: maximum length of input/output array.
Prepare the input UTF-8 string according to the draft SASL
ANONYMOUS profile. Returns 0 iff successful, or an error code.
-- Function: int stringprep_xmpp_nodeprep (char * IN, int MAXLEN)
IN: input/ouput array with string to prepare.
MAXLEN: maximum length of input/output array.
Prepare the input UTF-8 string according to the draft XMPP node
identifier profile. Returns 0 iff successful, or an error code.
-- Function: int stringprep_xmpp_resourceprep (char * IN, int MAXLEN)
IN: input/ouput array with string to prepare.
MAXLEN: maximum length of input/output array.
Prepare the input UTF-8 string according to the draft XMPP resource
identifier profile. Returns 0 iff successful, or an error code.
File: libidn.info, Node: Punycode Functions, Next: IDNA Functions, Prev: Stringprep Functions, Up: Top
5 Punycode Functions
********************
Punycode is a simple and efficient transfer encoding syntax designed for
use with Internationalized Domain Names in Applications. It uniquely
and reversibly transforms a Unicode string into an ASCII string. ASCII
characters in the Unicode string are represented literally, and
non-ASCII characters are represented by ASCII characters that are
allowed in host name labels (letters, digits, and hyphens). A general
algorithm called Bootstring allows a string of basic code points to
uniquely represent any string of code points drawn from a larger set.
Punycode is an instance of Bootstring that uses particular parameter
values, appropriate for IDNA.
5.1 Header file 'punycode.h'
============================
To use the functions explained in this chapter, you need to include the
file 'punycode.h' using:
#include <punycode.h>
5.2 Unicode Code Point Data Type
================================
The punycode function uses a special type to denote Unicode code points.
It is guaranteed to always be a 32 bit unsigned integer.
-- Punycode Unicode code point: uint32_t punycode_uint
A unsigned integer that hold Unicode code points.
5.3 Core Functions
==================
Note that the current implementation will fail if the 'input_length'
exceed 4294967295 (the size of 'punycode_uint'). This restriction may
be removed in the future. Meanwhile applications are encouraged to not
depend on this problem, and use 'sizeof' to initialize 'input_length'
and 'output_length'.
The functions provided are the following two entry points:
punycode_encode
---------------
-- Function: int punycode_encode (size_t INPUT_LENGTH, const
punycode_uint [] INPUT, const unsigned char [] CASE_FLAGS,
size_t * OUTPUT_LENGTH, char [] OUTPUT)
INPUT_LENGTH: The number of code points in the 'input' array and
the number of flags in the 'case_flags' array.
INPUT: An array of code points. They are presumed to be Unicode
code points, but that is not strictly REQUIRED. The array contains
code points, not code units. UTF-16 uses code units D800 through
DFFF to refer to code points 10000..10FFFF. The code points
D800..DFFF do not occur in any valid Unicode string. The code
points that can occur in Unicode strings (0..D7FF and E000..10FFFF)
are also called Unicode scalar values.
CASE_FLAGS: A 'NULL' pointer or an array of boolean values parallel
to the 'input' array. Nonzero (true, flagged) suggests that the
corresponding Unicode character be forced to uppercase after being
decoded (if possible), and zero (false, unflagged) suggests that it
be forced to lowercase (if possible). ASCII code points (0..7F)
are encoded literally, except that ASCII letters are forced to
uppercase or lowercase according to the corresponding case flags.
If 'case_flags' is a 'NULL' pointer then ASCII letters are left as
they are, and other code points are treated as unflagged.
OUTPUT_LENGTH: The caller passes in the maximum number of ASCII
code points that it can receive. On successful return it will
contain the number of ASCII code points actually output.
OUTPUT: An array of ASCII code points. It is *not*
null-terminated; it will contain zeros if and only if the 'input'
contains zeros. (Of course the caller can leave room for a
terminator and add one if needed.)
Converts a sequence of code points (presumed to be Unicode code
points) to Punycode.
Return value: The return value can be any of the 'Punycode_status'
values defined above except 'PUNYCODE_BAD_INPUT' . If not
'PUNYCODE_SUCCESS' , then 'output_size' and 'output' might contain
garbage.
punycode_decode
---------------
-- Function: int punycode_decode (size_t INPUT_LENGTH, const char []
INPUT, size_t * OUTPUT_LENGTH, punycode_uint [] OUTPUT,
unsigned char [] CASE_FLAGS)
INPUT_LENGTH: The number of ASCII code points in the 'input' array.
INPUT: An array of ASCII code points (0..7F).
OUTPUT_LENGTH: The caller passes in the maximum number of code
points that it can receive into the 'output' array (which is also
the maximum number of flags that it can receive into the
'case_flags' array, if 'case_flags' is not a 'NULL' pointer). On
successful return it will contain the number of code points
actually output (which is also the number of flags actually output,
if case_flags is not a null pointer). The decoder will never need
to output more code points than the number of ASCII code points in
the input, because of the way the encoding is defined. The number
of code points output cannot exceed the maximum possible value of a
punycode_uint, even if the supplied 'output_length' is greater than
that.
OUTPUT: An array of code points like the input argument of
'punycode_encode()' (see above).
CASE_FLAGS: A 'NULL' pointer (if the flags are not needed by the
caller) or an array of boolean values parallel to the 'output'
array. Nonzero (true, flagged) suggests that the corresponding
Unicode character be forced to uppercase by the caller (if
possible), and zero (false, unflagged) suggests that it be forced
to lowercase (if possible). ASCII code points (0..7F) are output
already in the proper case, but their flags will be set
appropriately so that applying the flags would be harmless.
Converts Punycode to a sequence of code points (presumed to be
Unicode code points).
Return value: The return value can be any of the 'Punycode_status'
values defined above. If not 'PUNYCODE_SUCCESS' , then
'output_length' , 'output' , and 'case_flags' might contain
garbage.
5.4 Error Handling
==================
punycode_strerror
-----------------
-- Function: const char * punycode_strerror (Punycode_status RC)
RC: an 'Punycode_status' return code.
Convert a return code integer to a text string. This string can be
used to output a diagnostic message to the user.
*PUNYCODE_SUCCESS:* Successful operation. This value is guaranteed
to always be zero, the remaining ones are only guaranteed to hold
non-zero values, for logical comparison purposes.
*PUNYCODE_BAD_INPUT:* Input is invalid.
*PUNYCODE_BIG_OUTPUT:* Output would exceed the space provided.
*PUNYCODE_OVERFLOW:* Input needs wider integers to process.
Return value: Returns a pointer to a statically allocated string
containing a description of the error with the return code 'rc' .
File: libidn.info, Node: IDNA Functions, Next: TLD Functions, Prev: Punycode Functions, Up: Top
6 IDNA Functions
****************
Until now, there has been no standard method for domain names to use
characters outside the ASCII repertoire. The IDNA document defines
internationalized domain names (IDNs) and a mechanism called IDNA for
handling them in a standard fashion. IDNs use characters drawn from a
large repertoire (Unicode), but IDNA allows the non-ASCII characters to
be represented using only the ASCII characters already allowed in
so-called host names today. This backward-compatible representation is
required in existing protocols like DNS, so that IDNs can be introduced
with no changes to the existing infrastructure. IDNA is only meant for
processing domain names, not free text.
6.1 Header file 'idna.h'
========================
To use the functions explained in this chapter, you need to include the
file 'idna.h' using:
#include <idna.h>
6.2 Control Flags
=================
The IDNA 'flags' parameter can take on the following values, or a
bit-wise inclusive or of any subset of the parameters:
-- Return code: Idna_flags IDNA_ALLOW_UNASSIGNED
Allow unassigned Unicode code points.
-- Return code: Idna_flags IDNA_USE_STD3_ASCII_RULES
Check output to make sure it is a STD3 conforming host name.
6.3 Prefix String
=================
-- Macro: #define IDNA_ACE_PREFIX
String with the official IDNA prefix, 'xn--'.
6.4 Core Functions
==================
The idea behind the IDNA function names are as follows: the
'idna_to_ascii_4i' and 'idna_to_unicode_44i' functions are the core IDNA
primitives. The '4' indicate that the function takes UCS-4 strings
(i.e., Unicode code points encoded in a 32-bit unsigned integer type) of
the specified length. The 'i' indicate that the data is written
"inline" into the buffer. This means the caller is responsible for
allocating (and de-allocating) the string, and providing the library
with the allocated length of the string. The output length is written
in the output length variable. The remaining functions all contain the
'z' indicator, which means the strings are zero terminated. All output
strings are allocated by the library, and must be de-allocated by the
caller. The '4' indicator again means that the string is UCS-4, the '8'
means the strings are UTF-8 and the 'l' indicator means the strings are
encoded in the encoding used by the current locale.
The functions provided are the following entry points:
idna_to_ascii_4i
----------------
-- Function: int idna_to_ascii_4i (const uint32_t * IN, size_t INLEN,
char * OUT, int FLAGS)
IN: input array with unicode code points.
INLEN: length of input array with unicode code points.
OUT: output zero terminated string that must have room for at least
63 characters plus the terminating zero.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
The ToASCII operation takes a sequence of Unicode code points that
make up one domain label and transforms it into a sequence of code
points in the ASCII range (0..7F). If ToASCII succeeds, the
original sequence and the resulting sequence are equivalent labels.
It is important to note that the ToASCII operation can fail.
ToASCII fails if any step of it fails. If any step of the ToASCII
operation fails on any label in a domain name, that domain name
MUST NOT be used as an internationalized domain name. The method
for deadling with this failure is application-specific.
The inputs to ToASCII are a sequence of code points, the
AllowUnassigned flag, and the UseSTD3ASCIIRules flag. The output
of ToASCII is either a sequence of ASCII code points or a failure
condition.
ToASCII never alters a sequence of code points that are all in the
ASCII range to begin with (although it could fail). Applying the
ToASCII operation multiple times has exactly the same effect as
applying it just once.
Return value: Returns 0 on success, or an 'Idna_rc' error code.
idna_to_unicode_44i
-------------------
-- Function: int idna_to_unicode_44i (const uint32_t * IN, size_t
INLEN, uint32_t * OUT, size_t * OUTLEN, int FLAGS)
IN: input array with unicode code points.
INLEN: length of input array with unicode code points.
OUT: output array with unicode code points.
OUTLEN: on input, maximum size of output array with unicode code
points, on exit, actual size of output array with unicode code
points.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
The ToUnicode operation takes a sequence of Unicode code points
that make up one domain label and returns a sequence of Unicode
code points. If the input sequence is a label in ACE form, then
the result is an equivalent internationalized label that is not in
ACE form, otherwise the original sequence is returned unaltered.
ToUnicode never fails. If any step fails, then the original input
sequence is returned immediately in that step.
The Punycode decoder can never output more code points than it
inputs, but Nameprep can, and therefore ToUnicode can. Note that
the number of octets needed to represent a sequence of code points
depends on the particular character encoding used.
The inputs to ToUnicode are a sequence of code points, the
AllowUnassigned flag, and the UseSTD3ASCIIRules flag. The output
of ToUnicode is always a sequence of Unicode code points.
Return value: Returns 'Idna_rc' error condition, but it must only
be used for debugging purposes. The output buffer is always
guaranteed to contain the correct data according to the
specification (sans malloc induced errors). NB! This means that
you normally ignore the return code from this function, as checking
it means breaking the standard.
6.5 Simplified ToASCII Interface
================================
idna_to_ascii_4z
----------------
-- Function: int idna_to_ascii_4z (const uint32_t * INPUT, char **
OUTPUT, int FLAGS)
INPUT: zero terminated input Unicode string.
OUTPUT: pointer to newly allocated output string.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
Convert UCS-4 domain name to ASCII string. The domain name may
contain several labels, separated by dots. The output buffer must
be deallocated by the caller.
Return value: Returns 'IDNA_SUCCESS' on success, or error code.
idna_to_ascii_8z
----------------
-- Function: int idna_to_ascii_8z (const char * INPUT, char ** OUTPUT,
int FLAGS)
INPUT: zero terminated input UTF-8 string.
OUTPUT: pointer to newly allocated output string.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
Convert UTF-8 domain name to ASCII string. The domain name may
contain several labels, separated by dots. The output buffer must
be deallocated by the caller.
Return value: Returns 'IDNA_SUCCESS' on success, or error code.
idna_to_ascii_lz
----------------
-- Function: int idna_to_ascii_lz (const char * INPUT, char ** OUTPUT,
int FLAGS)
INPUT: zero terminated input string encoded in the current locale's
character set.
OUTPUT: pointer to newly allocated output string.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
Convert domain name in the locale's encoding to ASCII string. The
domain name may contain several labels, separated by dots. The
output buffer must be deallocated by the caller.
Return value: Returns 'IDNA_SUCCESS' on success, or error code.
6.6 Simplified ToUnicode Interface
==================================
idna_to_unicode_4z4z
--------------------
-- Function: int idna_to_unicode_4z4z (const uint32_t * INPUT, uint32_t
** OUTPUT, int FLAGS)
INPUT: zero-terminated Unicode string.
OUTPUT: pointer to newly allocated output Unicode string.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
Convert possibly ACE encoded domain name in UCS-4 format into a
UCS-4 string. The domain name may contain several labels,
separated by dots. The output buffer must be deallocated by the
caller.
Return value: Returns 'IDNA_SUCCESS' on success, or error code.
idna_to_unicode_8z4z
--------------------
-- Function: int idna_to_unicode_8z4z (const char * INPUT, uint32_t **
OUTPUT, int FLAGS)
INPUT: zero-terminated UTF-8 string.
OUTPUT: pointer to newly allocated output Unicode string.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
Convert possibly ACE encoded domain name in UTF-8 format into a
UCS-4 string. The domain name may contain several labels,
separated by dots. The output buffer must be deallocated by the
caller.
Return value: Returns 'IDNA_SUCCESS' on success, or error code.
idna_to_unicode_8z8z
--------------------
-- Function: int idna_to_unicode_8z8z (const char * INPUT, char **
OUTPUT, int FLAGS)
INPUT: zero-terminated UTF-8 string.
OUTPUT: pointer to newly allocated output UTF-8 string.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
Convert possibly ACE encoded domain name in UTF-8 format into a
UTF-8 string. The domain name may contain several labels,
separated by dots. The output buffer must be deallocated by the
caller.
Return value: Returns 'IDNA_SUCCESS' on success, or error code.
idna_to_unicode_8zlz
--------------------
-- Function: int idna_to_unicode_8zlz (const char * INPUT, char **
OUTPUT, int FLAGS)
INPUT: zero-terminated UTF-8 string.
OUTPUT: pointer to newly allocated output string encoded in the
current locale's character set.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
Convert possibly ACE encoded domain name in UTF-8 format into a
string encoded in the current locale's character set. The domain
name may contain several labels, separated by dots. The output
buffer must be deallocated by the caller.
Return value: Returns 'IDNA_SUCCESS' on success, or error code.
idna_to_unicode_lzlz
--------------------
-- Function: int idna_to_unicode_lzlz (const char * INPUT, char **
OUTPUT, int FLAGS)
INPUT: zero-terminated string encoded in the current locale's
character set.
OUTPUT: pointer to newly allocated output string encoded in the
current locale's character set.
FLAGS: an 'Idna_flags' value, e.g., 'IDNA_ALLOW_UNASSIGNED' or
'IDNA_USE_STD3_ASCII_RULES' .
Convert possibly ACE encoded domain name in the locale's character
set into a string encoded in the current locale's character set.
The domain name may contain several labels, separated by dots. The
output buffer must be deallocated by the caller.
Return value: Returns 'IDNA_SUCCESS' on success, or error code.
6.7 Error Handling
==================
idna_strerror
-------------
-- Function: const char * idna_strerror (Idna_rc RC)
RC: an 'Idna_rc' return code.
Convert a return code integer to a text string. This string can be
used to output a diagnostic message to the user.
*IDNA_SUCCESS:* Successful operation. This value is guaranteed to
always be zero, the remaining ones are only guaranteed to hold
non-zero values, for logical comparison purposes.
*IDNA_STRINGPREP_ERROR:* Error during string preparation.
*IDNA_PUNYCODE_ERROR:* Error during punycode operation.
*IDNA_CONTAINS_NON_LDH:* For IDNA_USE_STD3_ASCII_RULES, indicate
that the string contains non-LDH ASCII characters.
*IDNA_CONTAINS_MINUS:* For IDNA_USE_STD3_ASCII_RULES, indicate that
the string contains a leading or trailing hyphen-minus (U+002D).
*IDNA_INVALID_LENGTH:* The final output string is not within the
(inclusive) range 1 to 63 characters.
*IDNA_NO_ACE_PREFIX:* The string does not contain the ACE prefix
(for ToUnicode).
*IDNA_ROUNDTRIP_VERIFY_ERROR:* The ToASCII operation on output
string does not equal the input.
*IDNA_CONTAINS_ACE_PREFIX:* The input contains the ACE prefix (for
ToASCII).
*IDNA_ICONV_ERROR:* Could not convert string in locale encoding.
*IDNA_MALLOC_ERROR:* Could not allocate buffer (this is typically a
fatal error).
*IDNA_DLOPEN_ERROR:* Could not dlopen the libcidn DSO (only used
internally in libc).
Return value: Returns a pointer to a statically allocated string
containing a description of the error with the return code 'rc' .
File: libidn.info, Node: TLD Functions, Next: PR29 Functions, Prev: IDNA Functions, Up: Top
7 TLD Functions
***************
Organizations that manage some Top Level Domains (TLDs) have published
tables with characters they accept within the domain. The reason may be
to reduce complexity that come from using the full Unicode range, and to
protect themselves from future (backwards incompatible) changes in the
IDN or Unicode specifications. Libidn implement an infrastructure for
defining and checking strings against such tables. Libidn also ship
some tables from TLDs that we have managed to get permission to use them
from. Because these tables are even less static than Unicode or
StringPrep tables, it is likely that they will be updated from time to
time (even in backwards incompatible ways). The Libidn interface
provide a "version" field for each TLD table, which can be compared for
equality to guarantee the same operation over time.
From a design point of view, you can regard the TLD tables for IDN as
the "localization" step that come after the "internationalization" step
provided by the IETF standards.
The TLD functionality rely on up-to-date tables. The latest version
of Libidn aim to provide these, but tables with unclear copying
conditions, or generally experimental tables, are not included. Some
such tables can be found at <https://github.com/gnuthor/tldchk>;.
7.1 Header file 'tld.h'
=======================
To use the functions explained in this chapter, you need to include the
file 'tld.h' using:
#include <tld.h>
7.2 Core Functions
==================
tld_check_4t
------------
-- Function: int tld_check_4t (const uint32_t * IN, size_t INLEN,
size_t * ERRPOS, const Tld_table * TLD)
IN: Array of unicode code points to process. Does not need to be
zero terminated.
INLEN: Number of unicode code points.
ERRPOS: Position of offending character is returned here.
TLD: A 'Tld_table' data structure representing the restrictions for
which the input should be tested.
Test each of the code points in 'in' for whether or not they are
allowed by the data structure in 'tld' , return the position of the
first character for which this is not the case in 'errpos' .
Return value: Returns the 'Tld_rc' value 'TLD_SUCCESS' if all code
points are valid or when 'tld' is null, 'TLD_INVALID' if a
character is not allowed, or additional error codes on general
failure conditions.
tld_check_4tz
-------------
-- Function: int tld_check_4tz (const uint32_t * IN, size_t * ERRPOS,
const Tld_table * TLD)
IN: Zero terminated array of unicode code points to process.
ERRPOS: Position of offending character is returned here.
TLD: A 'Tld_table' data structure representing the restrictions for
which the input should be tested.
Test each of the code points in 'in' for whether or not they are
allowed by the data structure in 'tld' , return the position of the
first character for which this is not the case in 'errpos' .
Return value: Returns the 'Tld_rc' value 'TLD_SUCCESS' if all code
points are valid or when 'tld' is null, 'TLD_INVALID' if a
character is not allowed, or additional error codes on general
failure conditions.
7.3 Utility Functions
=====================
tld_get_4
---------
-- Function: int tld_get_4 (const uint32_t * IN, size_t INLEN, char **
OUT)
IN: Array of unicode code points to process. Does not need to be
zero terminated.
INLEN: Number of unicode code points.
OUT: Zero terminated ascii result string pointer.
Isolate the top-level domain of 'in' and return it as an ASCII
string in 'out' .
Return value: Return 'TLD_SUCCESS' on success, or the corresponding
'Tld_rc' error code otherwise.
tld_get_4z
----------
-- Function: int tld_get_4z (const uint32_t * IN, char ** OUT)
IN: Zero terminated array of unicode code points to process.
OUT: Zero terminated ascii result string pointer.
Isolate the top-level domain of 'in' and return it as an ASCII
string in 'out' .
Return value: Return 'TLD_SUCCESS' on success, or the corresponding
'Tld_rc' error code otherwise.
tld_get_z
---------
-- Function: int tld_get_z (const char * IN, char ** OUT)
IN: Zero terminated character array to process.
OUT: Zero terminated ascii result string pointer.
Isolate the top-level domain of 'in' and return it as an ASCII
string in 'out' . The input string 'in' may be UTF-8, ISO-8859-1
or any ASCII compatible character encoding.
Return value: Return 'TLD_SUCCESS' on success, or the corresponding
'Tld_rc' error code otherwise.
tld_get_table
-------------
-- Function: const Tld_table * tld_get_table (const char * TLD, const
Tld_table ** TABLES)
TLD: TLD name (e.g. "com") as zero terminated ASCII byte string.
TABLES: Zero terminated array of 'Tld_table' info-structures for
TLDs.
Get the TLD table for a named TLD by searching through the given
TLD table array.
Return value: Return structure corresponding to TLD 'tld' by going
thru 'tables' , or return 'NULL' if no such structure is found.
tld_default_table
-----------------
-- Function: const Tld_table * tld_default_table (const char * TLD,
const Tld_table ** OVERRIDES)
TLD: TLD name (e.g. "com") as zero terminated ASCII byte string.
OVERRIDES: Additional zero terminated array of 'Tld_table'
info-structures for TLDs, or 'NULL' to only use library deault
tables.
Get the TLD table for a named TLD, using the internal defaults,
possibly overrided by the (optional) supplied tables.
Return value: Return structure corresponding to TLD 'tld_str' ,
first looking through 'overrides' then thru built-in list, or
'NULL' if no such structure found.
7.4 High-Level Wrapper Functions
================================
tld_check_4
-----------
-- Function: int tld_check_4 (const uint32_t * IN, size_t INLEN, size_t
* ERRPOS, const Tld_table ** OVERRIDES)
IN: Array of unicode code points to process. Does not need to be
zero terminated.
INLEN: Number of unicode code points.
ERRPOS: Position of offending character is returned here.
OVERRIDES: A 'Tld_table' array of additional domain restriction
structures that complement and supersede the built-in information.
Test each of the code points in 'in' for whether or not they are
allowed by the information in 'overrides' or by the built-in TLD
restriction data. When data for the same TLD is available both
internally and in 'overrides' , the information in 'overrides'
takes precedence. If several entries for a specific TLD are found,
the first one is used. If 'overrides' is 'NULL' , only the
built-in information is used. The position of the first offending
character is returned in 'errpos' .
Return value: Returns the 'Tld_rc' value 'TLD_SUCCESS' if all code
points are valid or when 'tld' is null, 'TLD_INVALID' if a
character is not allowed, or additional error codes on general
failure conditions.
tld_check_4z
------------
-- Function: int tld_check_4z (const uint32_t * IN, size_t * ERRPOS,
const Tld_table ** OVERRIDES)
IN: Zero-terminated array of unicode code points to process.
ERRPOS: Position of offending character is returned here.
OVERRIDES: A 'Tld_table' array of additional domain restriction
structures that complement and supersede the built-in information.
Test each of the code points in 'in' for whether or not they are
allowed by the information in 'overrides' or by the built-in TLD
restriction data. When data for the same TLD is available both
internally and in 'overrides' , the information in 'overrides'
takes precedence. If several entries for a specific TLD are found,
the first one is used. If 'overrides' is 'NULL' , only the
built-in information is used. The position of the first offending
character is returned in 'errpos' .
Return value: Returns the 'Tld_rc' value 'TLD_SUCCESS' if all code
points are valid or when 'tld' is null, 'TLD_INVALID' if a
character is not allowed, or additional error codes on general
failure conditions.
tld_check_8z
------------
-- Function: int tld_check_8z (const char * IN, size_t * ERRPOS, const
Tld_table ** OVERRIDES)
IN: Zero-terminated UTF8 string to process.
ERRPOS: Position of offending character is returned here.
OVERRIDES: A 'Tld_table' array of additional domain restriction
structures that complement and supersede the built-in information.
Test each of the characters in 'in' for whether or not they are
allowed by the information in 'overrides' or by the built-in TLD
restriction data. When data for the same TLD is available both
internally and in 'overrides' , the information in 'overrides'
takes precedence. If several entries for a specific TLD are found,
the first one is used. If 'overrides' is 'NULL' , only the
built-in information is used. The position of the first offending
character is returned in 'errpos' . Note that the error position
refers to the decoded character offset rather than the byte
position in the string.
Return value: Returns the 'Tld_rc' value 'TLD_SUCCESS' if all
characters are valid or when 'tld' is null, 'TLD_INVALID' if a
character is not allowed, or additional error codes on general
failure conditions.
tld_check_lz
------------
-- Function: int tld_check_lz (const char * IN, size_t * ERRPOS, const
Tld_table ** OVERRIDES)
IN: Zero-terminated string in the current locales encoding to
process.
ERRPOS: Position of offending character is returned here.
OVERRIDES: A 'Tld_table' array of additional domain restriction
structures that complement and supersede the built-in information.
Test each of the characters in 'in' for whether or not they are
allowed by the information in 'overrides' or by the built-in TLD
restriction data. When data for the same TLD is available both
internally and in 'overrides' , the information in 'overrides'
takes precedence. If several entries for a specific TLD are found,
the first one is used. If 'overrides' is 'NULL' , only the
built-in information is used. The position of the first offending
character is returned in 'errpos' . Note that the error position
refers to the decoded character offset rather than the byte
position in the string.
Return value: Returns the 'Tld_rc' value 'TLD_SUCCESS' if all
characters are valid or when 'tld' is null, 'TLD_INVALID' if a
character is not allowed, or additional error codes on general
failure conditions.
7.5 Error Handling
==================
tld_strerror
------------
-- Function: const char * tld_strerror (Tld_rc RC)
RC: tld return code
Convert a return code integer to a text string. This string can be
used to output a diagnostic message to the user.
*TLD_SUCCESS:* Successful operation. This value is guaranteed to
always be zero, the remaining ones are only guaranteed to hold
non-zero values, for logical comparison purposes.
*TLD_INVALID:* Invalid character found.
*TLD_NODATA:* No input data was provided.
*TLD_MALLOC_ERROR:* Error during memory allocation.
*TLD_ICONV_ERROR:* Error during iconv string conversion.
*TLD_NO_TLD:* No top-level domain found in domain string.
Return value: Returns a pointer to a statically allocated string
containing a description of the error with the return code 'rc' .
File: libidn.info, Node: PR29 Functions, Next: Examples, Prev: TLD Functions, Up: Top
8 PR29 Functions
****************
A deficiency in the specification of Unicode Normalization Forms has
been found. The consequence is that some strings can be normalized into
different strings by different implementations. In other words, two
different implementations may return different output for the same input
(because the interpretation of the specification is ambiguous).
Further, an implementation invoked again on the one of the output
strings may return a different string (because one of the interpretation
of the ambiguous specification make normalization non-idempotent).
Fortunately, only a select few character sequence exhibit this problem,
and none of them are expected to occur in natural languages (due to
different linguistic uses of the involved characters).
A full discussion of the problem may be found at:
<http://www.unicode.org/review/pr-29.html>;
The PR29 functions below allow you to detect the problem sequence.
So when would you want to use these functions? For most applications,
such as those using Nameprep for IDN, this is likely only to be an
interoperability problem. Thus, you may not want to care about it, as
the character sequences will rarely occur naturally. However, if you
are using a profile, such as SASLPrep, to process authentication tokens;
authorization tokens; or passwords, there is a real danger that
attackers may try to use the peculiarities in these strings to attack
parts of your system. As only a small number of strings, and no
naturally occurring strings, exhibit this problem, the conservative
approach of rejecting the strings is recommended. If this approach is
not used, you should instead verify that all parts of your system, that
process the tokens and passwords, use a NFKC implementation that produce
the same output for the same input.
Technically inclined readers may be interested in knowing more about
the implementation aspects of the PR29 flaw. *Note PR29 discussion::.
8.1 Header file 'pr29.h'
========================
To use the functions explained in this chapter, you need to include the
file 'pr29.h' using:
#include <pr29.h>
8.2 Core Functions
==================
pr29_4
------
-- Function: int pr29_4 (const uint32_t * IN, size_t LEN)
IN: input array with unicode code points.
LEN: length of input array with unicode code points.
Check the input to see if it may be normalized into different
strings by different NFKC implementations, due to an anomaly in the
NFKC specifications.
Return value: Returns the 'Pr29_rc' value 'PR29_SUCCESS' on
success, and 'PR29_PROBLEM' if the input sequence is a "problem
sequence" (i.e., may be normalized into different strings by
different implementations).
8.3 Utility Functions
=====================
pr29_4z
-------
-- Function: int pr29_4z (const uint32_t * IN)
IN: zero terminated array of Unicode code points.
Check the input to see if it may be normalized into different
strings by different NFKC implementations, due to an anomaly in the
NFKC specifications.
Return value: Returns the 'Pr29_rc' value 'PR29_SUCCESS' on
success, and 'PR29_PROBLEM' if the input sequence is a "problem
sequence" (i.e., may be normalized into different strings by
different implementations).
pr29_8z
-------
-- Function: int pr29_8z (const char * IN)
IN: zero terminated input UTF-8 string.
Check the input to see if it may be normalized into different
strings by different NFKC implementations, due to an anomaly in the
NFKC specifications.
Return value: Returns the 'Pr29_rc' value 'PR29_SUCCESS' on
success, and 'PR29_PROBLEM' if the input sequence is a "problem
sequence" (i.e., may be normalized into different strings by
different implementations), or 'PR29_STRINGPREP_ERROR' if there was
a problem converting the string from UTF-8 to UCS-4.
8.4 Error Handling
==================
pr29_strerror
-------------
-- Function: const char * pr29_strerror (Pr29_rc RC)
RC: an 'Pr29_rc' return code.
Convert a return code integer to a text string. This string can be
used to output a diagnostic message to the user.
*PR29_SUCCESS:* Successful operation. This value is guaranteed to
always be zero, the remaining ones are only guaranteed to hold
non-zero values, for logical comparison purposes.
*PR29_PROBLEM:* A problem sequence was encountered.
*PR29_STRINGPREP_ERROR:* The character set conversion failed (only
for 'pr29_8z()' ).
Return value: Returns a pointer to a statically allocated string
containing a description of the error with the return code 'rc' .
File: libidn.info, Node: Examples, Next: Invoking idn, Prev: PR29 Functions, Up: Top
9 Examples
**********
This chapter contains example code which illustrate how 'Libidn' can be
used when writing your own application.
* Menu:
* Example 1:: Example using stringprep.
* Example 2:: Example using punycode.
* Example 3:: Example using IDNA ToASCII.
* Example 4:: Example using IDNA ToUnicode.
* Example 5:: Example using TLD checking.
File: libidn.info, Node: Example 1, Next: Example 2, Up: Examples
9.1 Example 1
=============
This example demonstrates how the stringprep functions are used.
/* example.c --- Example code showing how to use stringprep().
* Copyright (C) 2002-2016 Simon Josefsson
*
* This file is part of GNU Libidn.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>;.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h> /* setlocale() */
#include <stringprep.h>
/*
* Compiling using libtool and pkg-config is recommended:
*
* $ libtool cc -o example example.c `pkg-config --cflags --libs libidn`
* $ ./example
* Input string encoded as `ISO-8859-1': ??
* Before locale2utf8 (length 2): aa 0a
* Before stringprep (length 3): c2 aa 0a
* After stringprep (length 2): 61 0a
* $
*
*/
int
main (void)
{
char buf[BUFSIZ];
char *p;
int rc;
size_t i;
setlocale (LC_ALL, "");
printf ("Input string encoded as `%s': ", stringprep_locale_charset ());
fflush (stdout);
if (!fgets (buf, BUFSIZ, stdin))
perror ("fgets");
buf[strlen (buf) - 1] = '\0';
printf ("Before locale2utf8 (length %ld): ", (long int) strlen (buf));
for (i = 0; i < strlen (buf); i++)
printf ("%02x ", (unsigned) buf[i] & 0xFF);
printf ("\n");
p = stringprep_locale_to_utf8 (buf);
if (p)
{
strcpy (buf, p);
free (p);
}
else
printf ("Could not convert string to UTF-8, continuing anyway...\n");
printf ("Before stringprep (length %ld): ", (long int) strlen (buf));
for (i = 0; i < strlen (buf); i++)
printf ("%02x ", (unsigned) buf[i] & 0xFF);
printf ("\n");
rc = stringprep (buf, BUFSIZ, 0, stringprep_nameprep);
if (rc != STRINGPREP_OK)
printf ("Stringprep failed (%d): %s\n", rc, stringprep_strerror (rc));
else
{
printf ("After stringprep (length %ld): ", (long int) strlen (buf));
for (i = 0; i < strlen (buf); i++)
printf ("%02x ", (unsigned) buf[i] & 0xFF);
printf ("\n");
}
return 0;
}
File: libidn.info, Node: Example 2, Next: Example 3, Prev: Example 1, Up: Examples
9.2 Example 2
=============
This example demonstrates how the punycode functions are used.
/* example2.c --- Example code showing how to use punycode.
* Copyright (C) 2002-2016 Simon Josefsson
* Copyright (C) 2002 Adam M. Costello
*
* This file is part of GNU Libidn.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>;.
*
*/
#include <locale.h> /* setlocale() */
/*
* This file is derived from RFC 3492 written by Adam M. Costello.
*
* Disclaimer and license: Regarding this entire document or any
* portion of it (including the pseudocode and C code), the author
* makes no guarantees and is not responsible for any damage resulting
* from its use. The author grants irrevocable permission to anyone
* to use, modify, and distribute it in any way that does not diminish
* the rights of anyone else to use, modify, and distribute it,
* provided that redistributed derivative works do not contain
* misleading author or version information. Derivative works need
* not be licensed under similar terms.
*
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <punycode.h>
/* For testing, we'll just set some compile-time limits rather than */
/* use malloc(), and set a compile-time option rather than using a */
/* command-line option. */
enum
{
unicode_max_length = 256,
ace_max_length = 256
};
static void
usage (char **argv)
{
fprintf (stderr,
"\n"
"%s -e reads code points and writes a Punycode string.\n"
"%s -d reads a Punycode string and writes code points.\n"
"\n"
"Input and output are plain text in the native character set.\n"
"Code points are in the form u+hex separated by whitespace.\n"
"Although the specification allows Punycode strings to contain\n"
"any characters from the ASCII repertoire, this test code\n"
"supports only the printable characters, and needs the Punycode\n"
"string to be followed by a newline.\n"
"The case of the u in u+hex is the force-to-uppercase flag.\n",
argv[0], argv[0]);
exit (EXIT_FAILURE);
}
static void
fail (const char *msg)
{
fputs (msg, stderr);
exit (EXIT_FAILURE);
}
static const char too_big[] =
"input or output is too large, recompile with larger limits\n";
static const char invalid_input[] = "invalid input\n";
static const char overflow[] = "arithmetic overflow\n";
static const char io_error[] = "I/O error\n";
/* The following string is used to convert printable */
/* characters between ASCII and the native charset: */
static const char print_ascii[] = "\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n" "\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n" " !\"#$%&'()*+,-./" "0123456789:;<=>?" "\0x40" /* at sign */
"ABCDEFGHIJKLMNO"
"PQRSTUVWXYZ[\\]^_" "`abcdefghijklmno" "pqrstuvwxyz{|}~\n";
int
main (int argc, char **argv)
{
enum punycode_status status;
int r;
size_t input_length, output_length, j;
unsigned char case_flags[unicode_max_length];
setlocale (LC_ALL, "");
if (argc != 2)
usage (argv);
if (argv[1][0] != '-')
usage (argv);
if (argv[1][2] != 0)
usage (argv);
if (argv[1][1] == 'e')
{
uint32_t input[unicode_max_length];
unsigned long codept;
char output[ace_max_length + 1], uplus[3];
int c;
/* Read the input code points: */
input_length = 0;
for (;;)
{
r = scanf ("%2s%lx", uplus, &codept);
if (ferror (stdin))
fail (io_error);
if (r == EOF || r == 0)
break;
if (r != 2 || uplus[1] != '+' || codept > (uint32_t) - 1)
{
fail (invalid_input);
}
if (input_length == unicode_max_length)
fail (too_big);
if (uplus[0] == 'u')
case_flags[input_length] = 0;
else if (uplus[0] == 'U')
case_flags[input_length] = 1;
else
fail (invalid_input);
input[input_length++] = codept;
}
/* Encode: */
output_length = ace_max_length;
status = punycode_encode (input_length, input, case_flags,
&output_length, output);
if (status == punycode_bad_input)
fail (invalid_input);
if (status == punycode_big_output)
fail (too_big);
if (status == punycode_overflow)
fail (overflow);
assert (status == punycode_success);
/* Convert to native charset and output: */
for (j = 0; j < output_length; ++j)
{
c = output[j];
assert (c >= 0 && c <= 127);
if (print_ascii[c] == 0)
fail (invalid_input);
output[j] = print_ascii[c];
}
output[j] = 0;
r = puts (output);
if (r == EOF)
fail (io_error);
return EXIT_SUCCESS;
}
if (argv[1][1] == 'd')
{
char input[ace_max_length + 2], *p, *pp;
uint32_t output[unicode_max_length];
/* Read the Punycode input string and convert to ASCII: */
if (!fgets (input, ace_max_length + 2, stdin))
fail (io_error);
if (ferror (stdin))
fail (io_error);
if (feof (stdin))
fail (invalid_input);
input_length = strlen (input) - 1;
if (input[input_length] != '\n')
fail (too_big);
input[input_length] = 0;
for (p = input; *p != 0; ++p)
{
pp = strchr (print_ascii, *p);
if (pp == 0)
fail (invalid_input);
*p = pp - print_ascii;
}
/* Decode: */
output_length = unicode_max_length;
status = punycode_decode (input_length, input, &output_length,
output, case_flags);
if (status == punycode_bad_input)
fail (invalid_input);
if (status == punycode_big_output)
fail (too_big);
if (status == punycode_overflow)
fail (overflow);
assert (status == punycode_success);
/* Output the result: */
for (j = 0; j < output_length; ++j)
{
r = printf ("%s+%04lX\n",
case_flags[j] ? "U" : "u", (unsigned long) output[j]);
if (r < 0)
fail (io_error);
}
return EXIT_SUCCESS;
}
usage (argv);
return EXIT_SUCCESS; /* not reached, but quiets compiler warning */
}
File: libidn.info, Node: Example 3, Next: Example 4, Prev: Example 2, Up: Examples
9.3 Example 3
=============
This example demonstrates how the library is used to convert
internationalized domain names into ASCII compatible names.
/* example3.c --- Example ToASCII() code showing how to use Libidn.
* Copyright (C) 2002-2016 Simon Josefsson
*
* This file is part of GNU Libidn.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>;.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h> /* setlocale() */
#include <stringprep.h> /* stringprep_locale_charset() */
#include <idna.h> /* idna_to_ascii_lz() */
/*
* Compiling using libtool and pkg-config is recommended:
*
* $ libtool cc -o example3 example3.c `pkg-config --cflags --libs libidn`
* $ ./example3
* Input domain encoded as `ISO-8859-1': www.ra"ksmo"rg??s??.example
* Read string (length 23): 77 77 77 2e 72 e4 6b 73 6d f6 72 67 e5 73 aa 2e 65 78 61 6d 70 6c 65
* ACE label (length 33): 'www.xn--rksmrgsa-0zap8p.example'
* 77 77 77 2e 78 6e 2d 2d 72 6b 73 6d 72 67 73 61 2d 30 7a 61 70 38 70 2e 65 78 61 6d 70 6c 65
* $
*
*/
int
main (void)
{
char buf[BUFSIZ];
char *p;
int rc;
size_t i;
setlocale (LC_ALL, "");
printf ("Input domain encoded as `%s': ", stringprep_locale_charset ());
fflush (stdout);
if (!fgets (buf, BUFSIZ, stdin))
perror ("fgets");
buf[strlen (buf) - 1] = '\0';
printf ("Read string (length %ld): ", (long int) strlen (buf));
for (i = 0; i < strlen (buf); i++)
printf ("%02x ", (unsigned) buf[i] & 0xFF);
printf ("\n");
rc = idna_to_ascii_lz (buf, &p, 0);
if (rc != IDNA_SUCCESS)
{
printf ("ToASCII() failed (%d): %s\n", rc, idna_strerror (rc));
return EXIT_FAILURE;
}
printf ("ACE label (length %ld): '%s'\n", (long int) strlen (p), p);
for (i = 0; i < strlen (p); i++)
printf ("%02x ", (unsigned) p[i] & 0xFF);
printf ("\n");
free (p);
return 0;
}
File: libidn.info, Node: Example 4, Next: Example 5, Prev: Example 3, Up: Examples
9.4 Example 4
=============
This example demonstrates how the library is used to convert ASCII
compatible names to internationalized domain names.
/* example4.c --- Example ToUnicode() code showing how to use Libidn.
* Copyright (C) 2002-2016 Simon Josefsson
*
* This file is part of GNU Libidn.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>;.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h> /* setlocale() */
#include <stringprep.h> /* stringprep_locale_charset() */
#include <idna.h> /* idna_to_unicode_lzlz() */
/*
* Compiling using libtool and pkg-config is recommended:
*
* $ libtool cc -o example4 example4.c `pkg-config --cflags --libs libidn`
* $ ./example4
* Input domain encoded as `ISO-8859-1': www.xn--rksmrgsa-0zap8p.example
* Read string (length 33): 77 77 77 2e 78 6e 2d 2d 72 6b 73 6d 72 67 73 61 2d 30 7a 61 70 38 70 2e 65 78 61 6d 70 6c 65
* ACE label (length 23): 'www.ra"ksmo"rg??sa.example'
* 77 77 77 2e 72 e4 6b 73 6d f6 72 67 e5 73 61 2e 65 78 61 6d 70 6c 65
* $
*
*/
int
main (void)
{
char buf[BUFSIZ];
char *p;
int rc;
size_t i;
setlocale (LC_ALL, "");
printf ("Input domain encoded as `%s': ", stringprep_locale_charset ());
fflush (stdout);
if (!fgets (buf, BUFSIZ, stdin))
perror ("fgets");
buf[strlen (buf) - 1] = '\0';
printf ("Read string (length %ld): ", (long int) strlen (buf));
for (i = 0; i < strlen (buf); i++)
printf ("%02x ", (unsigned) buf[i] & 0xFF);
printf ("\n");
rc = idna_to_unicode_lzlz (buf, &p, 0);
if (rc != IDNA_SUCCESS)
{
printf ("ToUnicode() failed (%d): %s\n", rc, idna_strerror (rc));
return EXIT_FAILURE;
}
printf ("ACE label (length %ld): '%s'\n", (long int) strlen (p), p);
for (i = 0; i < strlen (p); i++)
printf ("%02x ", (unsigned) p[i] & 0xFF);
printf ("\n");
free (p);
return 0;
}
File: libidn.info, Node: Example 5, Prev: Example 4, Up: Examples
9.5 Example 5
=============
This example demonstrates how the library is used to check a string for
invalid characters within a specific TLD.
/* example5.c --- Example TLD checking.
* Copyright (C) 2004-2016 Simon Josefsson
*
* This file is part of GNU Libidn.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>;.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Get stringprep_locale_charset, etc. */
#include <stringprep.h>
/* Get idna_to_ascii_8z, etc. */
#include <idna.h>
/* Get tld_check_4z. */
#include <tld.h>
/*
* Compiling using libtool and pkg-config is recommended:
*
* $ libtool cc -o example5 example5.c `pkg-config --cflags --libs libidn`
* $ ./example5
* Input domain encoded as `UTF-8': fooss.no
* Read string (length 8): 66 6f 6f c3 9f 2e 6e 6f
* ToASCII string (length 8): fooss.no
* ToUnicode string: U+0066 U+006f U+006f U+0073 U+0073 U+002e U+006e U+006f
* Domain accepted by TLD check
*
* $ ./example5
* Input domain encoded as `UTF-8': gr??????n.no
* Read string (length 12): 67 72 e2 82 ac e2 82 ac 6e 2e 6e 6f
* ToASCII string (length 16): xn--grn-l50aa.no
* ToUnicode string: U+0067 U+0072 U+20ac U+20ac U+006e U+002e U+006e U+006f
* Domain rejected by TLD check, Unicode position 2
*
*/
int
main (void)
{
char buf[BUFSIZ];
char *p;
uint32_t *r;
int rc;
size_t errpos, i;
printf ("Input domain encoded as `%s': ", stringprep_locale_charset ());
fflush (stdout);
if (!fgets (buf, BUFSIZ, stdin))
perror ("fgets");
buf[strlen (buf) - 1] = '\0';
printf ("Read string (length %ld): ", (long int) strlen (buf));
for (i = 0; i < strlen (buf); i++)
printf ("%02x ", (unsigned) buf[i] & 0xFF);
printf ("\n");
p = stringprep_locale_to_utf8 (buf);
if (p)
{
strcpy (buf, p);
free (p);
}
else
printf ("Could not convert string to UTF-8, continuing anyway...\n");
rc = idna_to_ascii_8z (buf, &p, 0);
if (rc != IDNA_SUCCESS)
{
printf ("idna_to_ascii_8z failed (%d): %s\n", rc, idna_strerror (rc));
return 2;
}
printf ("ToASCII string (length %ld): %s\n", (long int) strlen (p), p);
rc = idna_to_unicode_8z4z (p, &r, 0);
free (p);
if (rc != IDNA_SUCCESS)
{
printf ("idna_to_unicode_8z4z failed (%d): %s\n",
rc, idna_strerror (rc));
return 2;
}
printf ("ToUnicode string: ");
for (i = 0; r[i]; i++)
printf ("U+%04x ", r[i]);
printf ("\n");
rc = tld_check_4z (r, &errpos, NULL);
free (r);
if (rc == TLD_INVALID)
{
printf ("Domain rejected by TLD check, Unicode position %ld\n", (long int) errpos);
return 1;
}
else if (rc != TLD_SUCCESS)
{
printf ("tld_check_4z() failed (%d): %s\n", rc, tld_strerror (rc));
return 2;
}
printf ("Domain accepted by TLD check\n");
return 0;
}
File: libidn.info, Node: Invoking idn, Next: Emacs API, Prev: Examples, Up: Top
10 Invoking idn
***************
10.1 Name
=========
GNU Libidn (idn) - Internationalized Domain Names command line tool
10.2 Description
================
'idn' allows internationalized string preparation ('stringprep'),
encoding and decoding of punycode data, and IDNA ToASCII/ToUnicode
operations to be performed on the command line.
If strings are specified on the command line, they are used as input
and the computed output is printed to standard output 'stdout'. If no
strings are specified on the command line, the program read data, line
by line, from the standard input 'stdin', and print the computed output
to standard output. What processing is performed (e.g., ToASCII, or
Punycode encode) is indicated by options. If any errors are
encountered, the execution of the applications is aborted.
All strings are expected to be encoded in the preferred charset used
by your locale. Use '--debug' to find out what this charset is. You
can override the charset used by setting environment variable 'CHARSET'.
To process a string that starts with '-', for example '-foo', use
'--' to signal the end of parameters, as in 'idn --quiet -a -- -foo'.
10.3 Options
============
'idn' recognizes these commands:
-h, --help Print help and exit
-V, --version Print version and exit
-s, --stringprep Prepare string according to nameprep profile
-d, --punycode-decode Decode Punycode
-e, --punycode-encode Encode Punycode
-a, --idna-to-ascii Convert to ACE according to IDNA (default mode)
-u, --idna-to-unicode Convert from ACE according to IDNA
--allow-unassigned Toggle IDNA AllowUnassigned flag (default off)
--usestd3asciirules Toggle IDNA UseSTD3ASCIIRules flag (default off)
--no-tld Don't check string for TLD specific rules
Only for --idna-to-ascii and --idna-to-unicode
-n, --nfkc Normalize string according to Unicode v3.2 NFKC
-p, --profile=STRING Use specified stringprep profile instead
Valid stringprep profiles: `Nameprep',
`iSCSI', `Nodeprep', `Resourceprep',
`trace', `SASLprep'
--debug Print debugging information
--quiet Silent operation
10.4 Environment Variables
==========================
The CHARSET environment variable can be used to override what character
set to be used for decoding incoming data (i.e., on the command line or
on the standard input stream), and to encode data to the standard
output. If your system is set up correctly, however, the application
will guess which character set is used automatically. Example usage:
$ CHARSET=ISO-8859-1 idn --punycode-encode
...
10.5 Examples
=============
Standard usage, reading input from standard input:
jas@latte:~$ idn
libidn 0.3.5
Copyright 2002, 2003 Simon Josefsson.
GNU Libidn comes with NO WARRANTY, to the extent permitted by law.
You may redistribute copies of GNU Libidn under the terms of
the GNU Lesser General Public License. For more information
about these matters, see the file named COPYING.LIB.
Type each input string on a line by itself, terminated by a newline character.
ra"ksmo"rg??s.se
xn--rksmrgs-5wao1o.se
jas@latte:~$
Reading input from command line, and disable printing copyright and
license information:
jas@latte:~$ idn --quiet ra"ksmo"rg??s.se bl??baergr??d.no
xn--rksmrgs-5wao1o.se
xn--blbrgrd-fxak7p.no
jas@latte:~$
Accessing a specific StringPrep profile directly:
jas@latte:~$ idn --quiet --profile=SASLprep --stringprep tesst??
tessta
jas@latte:~$
10.6 Troubleshooting
====================
Getting character data encoded right, and making sure Libidn use the
same encoding, can be difficult. The reason for this is that most
systems encode character data in more than one character encoding, i.e.,
using 'UTF-8' together with 'ISO-8859-1' or 'ISO-2022-JP'. This problem
is likely to continue to exist until only one character encoding come
out as the evolutionary winner, or (more likely, at least to some
extents) forever.
The first step to troubleshooting character encoding problems with
Libidn is to use the '--debug' parameter to find out which character set
encoding 'idn' believe your locale uses.
jas@latte:~$ idn --debug --quiet ""
system locale uses charset `UTF-8'.
jas@latte:~$
If it prints 'ANSI_X3.4-1968' (i.e., 'US-ASCII'), this indicate you
have not configured your locale properly. To configure the locale, you
can, for example, use 'LANG=sv_SE.UTF-8; export LANG' at a '/bin/sh'
prompt, to set up your locale for a Swedish environment using 'UTF-8' as
the encoding.
Sometimes 'idn' appear to be unable to translate from your system
locale into 'UTF-8' (which is used internally), and you get an error
like the following:
jas@latte:~$ idn --quiet foo
idn: could not convert from ISO-8859-1 to UTF-8.
jas@latte:~$
The simplest explanation is that you haven't installed the 'iconv'
conversion tools. You can find it as a standalone library in GNU
Libiconv (<http://www.gnu.org/software/libiconv/>;). On many GNU/Linux
systems, this library is part of the system, but you may have to install
additional packages (e.g., 'glibc-locale' for Debian) to be able to use
it.
Another explanation is that the error is correct and you are feeding
'idn' invalid data. This can happen inadvertently if you are not
careful with the character set encoding you use. For example, if your
shell run in a 'ISO-8859-1' environment, and you invoke 'idn' with the
'CHARSET' environment variable as follows, you will feed it 'ISO-8859-1'
characters but force it to believe they are 'UTF-8'. Naturally this
will lead to an error, unless the byte sequences happen to be valid
'UTF-8'. Note that even if you don't get an error, the output may be
incorrect in this situation, because 'ISO-8859-1' and 'UTF-8' does not
in general encode the same characters as the same byte sequences.
jas@latte:~$ idn --quiet --debug ""
system locale uses charset `ISO-8859-1'.
jas@latte:~$ CHARSET=UTF-8 idn --quiet --debug ra"ksmo"rg??s
system locale uses charset `UTF-8'.
input[0] = U+0072
input[1] = U+4af3
input[2] = U+006d
input[3] = U+1b29e5
input[4] = U+0073
output[0] = U+0078
output[1] = U+006e
output[2] = U+002d
output[3] = U+002d
output[4] = U+0072
output[5] = U+006d
output[6] = U+0073
output[7] = U+002d
output[8] = U+0068
output[9] = U+0069
output[10] = U+0036
output[11] = U+0064
output[12] = U+0035
output[13] = U+0039
output[14] = U+0037
output[15] = U+0035
output[16] = U+0035
output[17] = U+0032
output[18] = U+0061
xn--rms-hi6d597552a
jas@latte:~$
The sense moral here is to forget about 'CHARSET' (configure your
locales properly instead) unless you know what you are doing, and if you
want to use it, do it carefully, after verifying with '--debug' that you
get the desired results.
File: libidn.info, Node: Emacs API, Next: Java API, Prev: Invoking idn, Up: Top
11 Emacs API
************
Included in Libidn are 'punycode.el' and 'idna.el' that provides an
Emacs Lisp API to (a limited set of) the Libidn API. This section
describes the API. Currently the IDNA API always set the
'UseSTD3ASCIIRules' flag and clear the 'AllowUnassigned' flag, in the
future there may be functionality to specify these flags via the API.
11.1 Punycode Emacs API
=======================
-- Variable: punycode-program
Name of the GNU Libidn 'idn' application. The default is 'idn'.
This variable can be customized.
-- Variable: punycode-environment
List of environment variable definitions prepended to
'process-environment'. The default is '("CHARSET=UTF-8")'. This
variable can be customized.
-- Variable: punycode-encode-parameters
List of parameters passed to PUNYCODE-PROGRAM to invoke punycode
encoding mode. The default is '("--quiet" "--punycode-encode")'.
This variable can be customized.
-- Variable: punycode-decode-parameters
Parameters passed to PUNYCODE-PROGRAM to invoke punycode decoding
mode. The default is '("--quiet" "--punycode-decode")'. This
variable can be customized.
-- Function: punycode-encode string
Returns a Punycode encoding of the STRING, after converting the
input into UTF-8.
-- Function: punycode-decode string
Returns a possibly multibyte string which is the decoding of the
STRING which is a punycode encoded string.
11.2 IDNA Emacs API
===================
-- Variable: idna-program
Name of the GNU Libidn 'idn' application. The default is 'idn'.
This variable can be customized.
-- Variable: idna-environment
List of environment variable definitions prepended to
'process-environment'. The default is '("CHARSET=UTF-8")'. This
variable can be customized.
-- Variable: idna-to-ascii-parameters
List of parameters passed to IDNA-PROGRAM to invoke IDNA ToASCII
mode. The default is '("--quiet" "--idna-to-ascii"
"--usestd3asciirules")'. This variable can be customized.
-- Variable: idna-to-unicode-parameters
Parameters passed IDNA-PROGRAM to invoke IDNA ToUnicode mode. The
default is '("--quiet" "--idna-to-unicode" "--usestd3asciirules")'.
This variable can be customized.
-- Function: idna-to-ascii string
Returns an ASCII Compatible Encoding (ACE) of the string computed
by the IDNA ToASCII operation on the input STRING, after converting
the input to UTF-8.
-- Function: idna-to-unicode string
Returns a possibly multibyte string which is the output of the IDNA
ToUnicode operation computed on the input STRING.
File: libidn.info, Node: Java API, Next: C# API, Prev: Emacs API, Up: Top
12 Java API
***********
Libidn has been ported to the Java programming language, and as a
consequence most of the API is available to native Java applications.
This section contain notes on this support, complete documentation is
pending.
The Java library, if Libidn has been built with Java support (*note
Downloading and Installing::), will be placed in 'java/libidn-1.34.jar'.
The source code is below 'java/' in Maven directory layout, and there is
a Maven 'pom.xml' build script as well. Source code files are in
'java/src/main/java/gnu/inet/encoding/'.
12.1 Overview
=============
This package provides a Java implementation of the Internationalized
Domain Names in Applications (IDNA) standard. It is written entirely in
Java and does not require any additional libraries to be set up.
The gnu.inet.encoding.IDNA class offers two public functions, toASCII
and toUnicode which can be used as follows:
gnu.inet.encoding.IDNA.toASCII("blo"ds.zu"g");
gnu.inet.encoding.IDNA.toUnicode("xn--blds-6qa.xn--zg-xka");
12.2 Miscellaneous Programs
===========================
The 'java/src/util/java/' directory contains several programs that are
related to the Java part of GNU Libidn, but that don't need to be
included in the main source tree or the JAR file.
12.2.1 GenerateRFC3454
----------------------
This program parses RFC3454 and creates the RFC3454.java program that is
required during the StringPrep phase.
The RFC can be found at various locations, for example at
<http://www.ietf.org/rfc/rfc3454.txt>;.
Invoke the program as follows:
$ java GenerateRFC3454
Creating RFC3454.java... Ok.
12.2.2 GenerateNFKC
-------------------
The GenerateNFKC program parses the Unicode character database file and
generates all the tables required for NFKC. This program requires the
two files UnicodeData.txt and CompositionExclusions.txt of version 3.2
of the Unicode files. Note that RFC3454 (Stringprep) defines that
Unicode version 3.2 is to be used, not the latest version.
The Unicode data files can be found at
<http://www.unicode.org/Public/>;.
Invoke the program as follows:
$ java GenerateNFKC
Creating CombiningClass.java... Ok.
Creating DecompositionKeys.java... Ok.
Creating DecompositionMappings.java... Ok.
Creating Composition.java... Ok.
12.2.3 TestIDNA
---------------
The TestIDNA program allows to test the IDNA implementation manually or
against Simon Josefsson's test vectors.
The test vectors can be found at the Libidn homepage,
<http://www.gnu.org/software/libidn/>;.
To test the transformation manually, use:
$ java -cp .:/usr/share/java/libidn.jar TestIDNA -a <string to test>
Input: <string to test>
Output: <toASCII(string to test)>
$ java -cp .:/usr/share/java/libidn.jar TestIDNA -u <string to test>
Input: <string to test>
Output: <toUnicode(string to test)>
To test against draft-josefsson-idn-test-vectors.html, use:
$ java -cp .:/usr/share/java/libidn/libidn.jar TestIDNA -t
No errors detected!
12.2.4 TestNFKC
---------------
The TestNFKC program allows to test the NFKC implementation manually or
against the NormalizationTest.txt file from the Unicode data files.
To test the normalization manually, use:
$ java -cp .:/usr/share/java/libidn.jar TestNFKC <string to test>
Input: <string to test>
Output: <nfkc version of the string to test>
To test against NormalizationTest.txt:
$ java -cp .:/usr/share/java/libidn.jar TestNFKC
No errors detected!
12.3 Possible Problems
======================
Beware of Bugs: This Java API needs a lot more testing, especially with
"exotic" character sets. While it works for me, it may not work for
you.
Encoding of your Java sources: If you are using non-ASCII characters
in your Java source code, make sure javac compiles your programs with
the correct encoding. If necessary specify the encoding using the
-encoding parameter.
Java Unicode handling: Java 1.4 only handles 16-bit Unicode code
points (i.e. characters in the Basic Multilingual Plane), this
implementation therefore ignores all references to so-called
Supplementary Characters (U+10000 to U+10FFFF). Starting from Java 1.5,
these characters will also be supported by Java, but this will require
changes to this library. See also the next section.
12.4 A Note on Java and Unicode
===============================
This library uses Java's built-in 'char' datatype. Up to Java 1.4, this
datatype only supports 16-bit Unicode code points, also called the Basic
Multilingual Plane. For this reason, this library doesn't work for
Supplementary Characters (i.e. characters from U+10000 to U+10FFFF).
All references to such characters are silently ignored.
Starting from Java 1.5, also Supplementary Characters will be
supported. However, this will require changes in the present version of
the library. Java 1.5 is currently in beta status.
For more information refer to the documentation of
java.lang.Character in the JDK API.
File: libidn.info, Node: C# API, Next: Acknowledgements, Prev: Java API, Up: Top
13 C# API
*********
The Libidn library has been ported to the C# language. The port reside
in the top-level 'csharp/' directory. Currently, no further
documentation about the implementation or the API is available.
However, the C# port was based on the Java port, and the API is exactly
the same as in the Java version. The help files for the Java API may
thus be useful.
File: libidn.info, Node: Acknowledgements, Next: History, Prev: C# API, Up: Top
14 Acknowledgements
*******************
The punycode implementation was taken from the IETF IDN Punycode
specification, by Adam M. Costello. The TLD code was contributed by
Thomas Jacob. The Java implementation was contributed by Oliver Hitz.
The C# implementation was contributed by Alexander Gnauck. The Unicode
tables were provided by Unicode, Inc. Some functions for dealing with
Unicode (see nfkc.c and toutf8.c) were borrowed from GLib, downloaded
from <http://www.gtk.org/>;. The manual borrowed text from Libgcrypt by
Werner Koch.
Inspiration for many things that, consciously or not, have gone into
this package is due to a number of free software package that the author
has been exposed to. The author wishes to acknowledge the free software
community in general, for giving an example on what role software
development can play in the modern society.
Several people reported bugs, sent patches or suggested improvements,
see the file THANKS in the top-level directory of the source code.
File: libidn.info, Node: History, Next: PR29 discussion, Prev: Acknowledgements, Up: Top
15 History
**********
The complete history of user visible changes is stored in the file
'NEWS' in the top-level directory of the source code tree. The complete
history of modifications to each file is stored in the file 'ChangeLog'
in the same directory. This section contain a condensed version of that
information, in the form of "milestones" for the project.
Stringprep implementation.
Version 0.0.0 released on 2002-11-05.
IDNA and Punycode implementations, part of the GNU project.
Version 0.1.0 released on 2003-01-05.
Uses official IDNA ACE prefix 'xn--'.
Version 0.1.7 released on 2003-02-12.
Command line interface.
Version 0.1.11 released on 2003-02-26.
GNU Libc add-on proposed.
Version 0.1.12 released on 2003-03-06.
Interoperability testing during IDNConnect.
Version 0.3.1 released on 2003-10-02.
TLD restriction testing.
Version 0.4.0 released on 2004-02-28.
GNU Libc add-on integrated.
Version 0.4.1 released on 2004-03-08.
Native Java implementation.
Version 0.4.2-0.4.9 released between 2004-03-20 and 2004-06-11.
PR-29 functions for "problem sequences".
Version 0.5.0 released on 2004-06-26.
Many small portability fixes and wider use.
Version 0.5.1 through 0.5.20, released between 2004-07-09 and
2005-10-23.
Native C# implementation.
Version 0.6.0 released on 2005-12-03.
Windows support through cross-compilation.
Version 0.6.1 released on 2006-01-20.
Library declared stable by releasing v1.0.
Version 1.0 released on 2007-07-31.
File: libidn.info, Node: PR29 discussion, Next: On Label Separators, Prev: History, Up: Top
Appendix A PR29 discussion
**************************
If you wish to experiment with a modified Unicode NFKC implementation
according to the PR29 proposal, you may find the following bug report
useful. However, I have not verified that the suggested modifications
are correct. For reference, I'm including my response to the report as
well.
From: Rick McGowan <rick AT unicode.org>
Subject: Possible bug and status of PR 29 change(s)
To: bug-libidn AT gnu.org
Date: Wed, 27 Oct 2004 14:49:17 -0700
Hello. On behalf of the Unicode Consortium editorial committee, I would
like to find out more information about the PR 29 fixes, if any, and
functions in Libidn. Your implementation was listed in the text of PR29 as
needing investigation, so I am following up on several implementations.
The UTC has accepted the proposed fix to D2 as outlined in PR29, and a new
draft of UAX #15 has been issued.
I have looked at Libidn 0.5.8 (today), and there may still be a possible
bug in NFKC.java and nfkc.c.
------------------------------------------------------
1. In NFKC.java, this line in canonicalOrdering():
if (i > 0 && (last_cc == 0 || last_cc != cc)) {
should perhaps be changed to:
if (i > 0 && (last_cc == 0 || last_cc < cc)) {
but I'm not sure of the sense of this comparison.
------------------------------------------------------
2. In nfkc.c, function _g_utf8_normalize_wc() has this code:
if (i > 0 &&
(last_cc == 0 || last_cc != cc) &&
combine (wc_buffer[last_start], wc_buffer[i],
&wc_buffer[last_start]))
{
This appears to have the same bug as the current Python implementation (in
Python 2.3.4). The code should be checking, as per new rule D2 UAX #15
update, that the next combining character is the same or HIGHER than the
current one. It now checks to see if it's non-zero and not equal.
The above line(s) should perhaps be changed to:
if (i > 0 &&
(last_cc == 0 || last_cc < cc) &&
combine (wc_buffer[last_start], wc_buffer[i],
&wc_buffer[last_start]))
{
but I'm not sure of the sense of the comparison (< or > or <=?) here.
In the text of PR29, I will be marking Libidn as "needs change" and adding
the version number that I checked. If any further change is made, please
let me know the release version, and I'll update again.
Regards,
Rick McGowan
From: Simon Josefsson <jas AT extundo.com>
Subject: Re: Possible bug and status of PR 29 change(s)
To: Rick McGowan <rick AT unicode.org>
Cc: bug-libidn AT gnu.org
Date: Thu, 28 Oct 2004 09:47:47 +0200
Rick McGowan <rick AT unicode.org> writes:
> Hello. On behalf of the Unicode Consortium editorial committee, I would
> like to find out more information about the PR 29 fixes, if any, and
> functions in Libidn. Your implementation was listed in the text of PR29 as
> needing investigation, so I am following up on several implementations.
>
> The UTC has accepted the proposed fix to D2 as outlined in PR29, and a new
> draft of UAX #15 has been issued.
>
> I have looked at Libidn 0.5.8 (today), and there may still be a possible
> bug in NFKC.java and nfkc.c.
Hello Rick.
I believe the current behavior is intentional. Libidn do not aim to
implement latest-and-greatest NFKC, it aim to implement the NFKC
functionality required for StringPrep and IDN. As you may know,
StringPrep/IDN reference Unicode 3.2.0, and explicitly says any later
changes (which I consider PR29 as) do not apply.
In fact, I believe that would I incorporate the changes suggested in
PR29, I would in fact be violating the IDN specifications.
Thanks for looking into the code and finding the place where the
change could be made. I'll see if I can mention this in the manual
somewhere, for technically interested readers.
Regards,
Simon
File: libidn.info, Node: On Label Separators, Next: Copying Information, Prev: PR29 discussion, Up: Top
Appendix B On Label Separators
******************************
Some strings contains characters whose NFKC normalized form contain the
ASCII dot (0x2E, "."). Examples of these characters are U+2024 (ONE DOT
LEADER) and U+248C (DIGIT FIVE FULL STOP). The strings have the
interesting property that their IDNA ToASCII output will contain
embedded dots. For example:
ToASCII (hi U+248C com) = hi5.com
ToASCII (ra"ksmo"rg??s U+2024 com) = xn--rksmrgs.com-l8as9u
This demonstrate the two general cases: The first where the ASCII dot
is part of an output that do not begin with the IDN prefix 'xn--'. The
second example illustrate when the dot is part of IDN prefixed with
'xn--'.
The input strings are, from the DNS point of view, a single label.
The IDNA algorithm translate one label at a time. Thus, the output is
expected to be only one label. What is important here is to make sure
the DNS resolver receives the correct query. The DNS protocol does not
use the dot to delimit labels on the wire, rather it uses length-value
pairs. Thus the correct query would be for '{7}hi5.com' and
'{22}xn--rksmrgs.com-l8as9u' respectively.
Some implementations (1) have decided that these inputs strings are
potentially confusing for the user. The string 'hi U+248C com' looks
like 'hi5.com' on systems that support Unicode properly. These
implementations do not follow RFC 3490. They yield:
ToASCII (hi U+248C com) = hi5.com
ToASCII (ra"ksmo"rg??s U+2024 com) = xn--rksmrgs-5wao1o.com
The DNS query they perform are '{3}hi5{3}com' and
'{18}xn--rksmrgs-5wao1o{3}com' respectively. Arguably, this leads to a
better user experience, and suggests that the IDNA specification is
sub-optimal in this area.
B.1 Recommended Workaround
==========================
It has been suggested to normalize the entire input string using NFKC
before passing it to IDNA ToASCII. You may use
'stringprep_utf8_nfkc_normalize' or 'stringprep_ucs4_nfkc_normalize'.
This appears to lead to similar behaviour as IE/Firefox, which would
avoid the problem, but this needs to be confirmed. Feel free to discuss
the issue with us.
Alternative workarounds are being considered. Eventually Libidn may
implement a new flag to the 'idna_*' functions that implements a
recommended way to work around this problem.
---------- Footnotes ----------
(1) Notably Microsoft's Internet Explorer and Mozilla's Firefox, but
not Apple's Safari.
File: libidn.info, Node: Copying Information, Next: Function and Variable Index, Prev: On Label Separators, Up: Top
Appendix C Copying Information
******************************
* Menu:
* GNU Free Documentation License:: License for copying this manual.
File: libidn.info, Node: GNU Free Documentation License, Up: Copying Information
C.1 GNU Free Documentation License
==================================
Version 1.3, 3 November 2008
Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
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====================================================
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File: libidn.info, Node: Function and Variable Index, Next: Concept Index, Prev: Copying Information, Up: Top
Function and Variable Index
***************************
* Menu:
* idna-to-ascii: Emacs API. (line 64)
* idna-to-unicode: Emacs API. (line 69)
* idna_strerror: IDNA Functions. (line 309)
* idna_to_ascii_4i: IDNA Functions. (line 66)
* idna_to_ascii_4z: IDNA Functions. (line 150)
* idna_to_ascii_8z: IDNA Functions. (line 168)
* idna_to_ascii_lz: IDNA Functions. (line 186)
* idna_to_unicode_44i: IDNA Functions. (line 104)
* idna_to_unicode_4z4z: IDNA Functions. (line 208)
* idna_to_unicode_8z4z: IDNA Functions. (line 227)
* idna_to_unicode_8z8z: IDNA Functions. (line 246)
* idna_to_unicode_8zlz: IDNA Functions. (line 265)
* idna_to_unicode_lzlz: IDNA Functions. (line 285)
* idn_free: Memory handling under Windows.
(line 30)
* pr29_4: PR29 Functions. (line 54)
* pr29_4z: PR29 Functions. (line 74)
* pr29_8z: PR29 Functions. (line 89)
* pr29_strerror: PR29 Functions. (line 108)
* punycode-decode: Emacs API. (line 38)
* punycode-encode: Emacs API. (line 34)
* punycode_decode: Punycode Functions. (line 92)
* punycode_encode: Punycode Functions. (line 48)
* punycode_strerror: Punycode Functions. (line 138)
* stringprep: Stringprep Functions.
(line 124)
* stringprep_4i: Stringprep Functions.
(line 54)
* stringprep_4zi: Stringprep Functions.
(line 93)
* stringprep_check_version: Version Check. (line 15)
* stringprep_convert: Utility Functions. (line 163)
* stringprep_iscsi: Stringprep Functions.
(line 257)
* stringprep_locale_charset: Utility Functions. (line 141)
* stringprep_locale_to_utf8: Utility Functions. (line 180)
* stringprep_nameprep_no_unassigned: Stringprep Functions.
(line 246)
* stringprep_plain: Stringprep Functions.
(line 266)
* stringprep_profile: Stringprep Functions.
(line 159)
* stringprep_strerror: Stringprep Functions.
(line 193)
* stringprep_ucs4_nfkc_normalize: Utility Functions. (line 97)
* stringprep_ucs4_to_utf8: Utility Functions. (line 50)
* stringprep_unichar_to_utf8: Utility Functions. (line 24)
* stringprep_utf8_nfkc_normalize: Utility Functions. (line 112)
* stringprep_utf8_to_locale: Utility Functions. (line 192)
* stringprep_utf8_to_ucs4: Utility Functions. (line 73)
* stringprep_utf8_to_unichar: Utility Functions. (line 38)
* stringprep_xmpp_nodeprep: Stringprep Functions.
(line 275)
* stringprep_xmpp_resourceprep: Stringprep Functions.
(line 284)
* tld_check_4: TLD Functions. (line 174)
* tld_check_4t: TLD Functions. (line 42)
* tld_check_4tz: TLD Functions. (line 66)
* tld_check_4z: TLD Functions. (line 203)
* tld_check_8z: TLD Functions. (line 229)
* tld_check_lz: TLD Functions. (line 257)
* tld_default_table: TLD Functions. (line 153)
* tld_get_4: TLD Functions. (line 90)
* tld_get_4z: TLD Functions. (line 108)
* tld_get_table: TLD Functions. (line 137)
* tld_get_z: TLD Functions. (line 122)
* tld_strerror: TLD Functions. (line 289)
File: libidn.info, Node: Concept Index, Prev: Function and Variable Index, Up: Top
Concept Index
*************
* Menu:
* AIX: Supported Platforms. (line 74)
* ARM: Supported Platforms. (line 128)
* Autoconf tests: Autoconf tests. (line 6)
* command line: Invoking idn. (line 5)
* Compiling your application: Building the source. (line 6)
* Configure tests: Autoconf tests. (line 6)
* Contributing: Contributing. (line 6)
* de-allocation: Memory handling under Windows.
(line 6)
* Debian: Supported Platforms. (line 10)
* Debian <1>: Supported Platforms. (line 22)
* Download: Downloading and Installing.
(line 6)
* Examples: Examples. (line 6)
* FDL, GNU Free Documentation License: GNU Free Documentation License.
(line 6)
* free: Memory handling under Windows.
(line 6)
* FreeBSD: Supported Platforms. (line 110)
* Hacking: Contributing. (line 6)
* heap memory: Memory handling under Windows.
(line 6)
* HP-UX: Supported Platforms. (line 82)
* IBM: Supported Platforms. (line 136)
* idn: Invoking idn. (line 6)
* IDNA Functions: IDNA Functions. (line 6)
* Installation: Downloading and Installing.
(line 6)
* invoking idn: Invoking idn. (line 6)
* IRIX: Supported Platforms. (line 70)
* MacOS X: Supported Platforms. (line 116)
* MacOS X <1>: Supported Platforms. (line 120)
* Mandrake: Supported Platforms. (line 66)
* Memory handling: Memory handling under Windows.
(line 6)
* Microsoft: Supported Platforms. (line 132)
* mingw32: Supported Platforms. (line 132)
* Motorola Coldfire: Supported Platforms. (line 124)
* NetBSD: Supported Platforms. (line 100)
* OpenBSD: Supported Platforms. (line 105)
* OpenPower 720: Supported Platforms. (line 45)
* OS/2: Supported Platforms. (line 136)
* PR29 Functions: PR29 Functions. (line 6)
* Punycode Functions: Punycode Functions. (line 6)
* RedHat: Supported Platforms. (line 49)
* RedHat <1>: Supported Platforms. (line 54)
* RedHat <2>: Supported Platforms. (line 62)
* RedHat Advanced Server: Supported Platforms. (line 58)
* Reporting Bugs: Bug Reports. (line 6)
* Solaris: Supported Platforms. (line 87)
* Solaris <1>: Supported Platforms. (line 91)
* Solaris <2>: Supported Platforms. (line 95)
* Stringprep Functions: Stringprep Functions.
(line 6)
* SuSE: Supported Platforms. (line 31)
* SuSE Linux: Supported Platforms. (line 36)
* SuSE Linux <1>: Supported Platforms. (line 40)
* SuSE Linux <2>: Supported Platforms. (line 45)
* TLD Functions: TLD Functions. (line 6)
* Tru64: Supported Platforms. (line 26)
* uClibc: Supported Platforms. (line 124)
* uClinux: Supported Platforms. (line 124)
* Utility Functions: Utility Functions. (line 6)
* Windows: Supported Platforms. (line 78)
* Windows <1>: Supported Platforms. (line 132)
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