
GNU Libidn

   This manual is last updated 15 December 2003 for version 0.3.5
   of GNU Libidn.

   Copyright  2002, 2003 Simon Josefsson.

   Permission is granted to copy, distribute and/or modify this
   document under the terms of the GNU Free Documentation
   License, Version 1.1 or any later version published by the
   Free Software Foundation; with the Invariant Sections
   including "Commercial Support", with the Front-Cover Texts
   being "A GNU Manual," and with the Back-Cover Texts as in (a)
   below. A copy of the license is included in the section
   entitled "GNU Free Documentation License."

   (a) The FSF's Back-Cover Text is: "You have freedom to copy
   and modify this GNU Manual, like GNU software. Copies
   published by the Free Software Foundation raise funds for GNU
   development."
     _________________________________________________________

   Table of Contents
   1. GNU Libidn
   2. Introduction

        2.1. Getting Started
        2.2. Features
        2.3. Supported Platforms
        2.4. Commercial Support
        2.5. Downloading and Installing
        2.6. Bug Reports
        2.7. Contributing

   3. Preparation

        3.1. Header
        3.2. Initialization
        3.3. Version Check
        3.4. Building the source
        3.5. Autoconf tests

              3.5.1. Autoconf test via pkg-config
              3.5.2. Standalone Autoconf test

   4. Utility Functions

        4.1. Header file stringprep.h
        4.2. Unicode Encoding Transformation
        4.3. Unicode Normalization
        4.4. Character Set Conversion

   5. Stringprep Functions

        5.1. Header file stringprep.h
        5.2. Defining A Stringprep Profile
        5.3. Return Codes
        5.4. Control Flags
        5.5. Core Functions
        5.6. Stringprep Profile Macros

   6. Punycode Functions

        6.1. Header file punycode.h
        6.2. Return Codes
        6.3. Unicode Code Point Type
        6.4. Core Functions

   7. IDNA Functions

        7.1. Header file idna.h
        7.2. Return Codes
        7.3. Control Flags
        7.4. Prefix String
        7.5. Core Functions
        7.6. Simplified ToASCII Interface
        7.7. Simplified ToUnicode Interface

   8. Examples

        8.1. Example 1
        8.2. Example 2
        8.3. Example 3
        8.4. Example 4

   9. Invoking idn

        9.1. Name
        9.2. Description
        9.3. Options
        9.4. Environment Variables
        9.5. Examples

   10. Emacs API

        10.1. Punycode Emacs API
        10.2. IDNA Emacs API

   11. Acknowledgements
   Concept Index
   Function and Variable Index
   A. Copying The Library

        A.1. Preamble
        A.2. How to Apply These Terms to Your New Libraries

   B. Copying This Manual

        B.1. GNU Free Documentation License
        B.2. How to use this License for your documents
     _________________________________________________________

Chapter 1. GNU Libidn

   This manual is last updated 15 December 2003 for version 0.3.5
   of GNU Libidn.

   Copyright  2002, 2003 Simon Josefsson.

   Permission is granted to copy, distribute and/or modify this
   document under the terms of the GNU Free Documentation
   License, Version 1.1 or any later version published by the
   Free Software Foundation; with the Invariant Sections
   including "Commercial Support", with the Front-Cover Texts
   being "A GNU Manual," and with the Back-Cover Texts as in (a)
   below. A copy of the license is included in the section
   entitled "GNU Free Documentation License."

   (a) The FSF's Back-Cover Text is: "You have freedom to copy
   and modify this GNU Manual, like GNU software. Copies
   published by the Free Software Foundation raise funds for GNU
   development."
     _________________________________________________________

Chapter 2. Introduction

   GNU Libidn is an implementation of the Stringprep, Punycode
   and IDNA specifications defined by the IETF Internationalized
   Domain Names (IDN) working group, used for internationalized
   domain names. The package is available under the GNU Lesser
   General Public License.

   The library contains a generic Stringprep implementation that
   does Unicode 3.2 NFKC normalization, mapping and prohibitation
   of characters, and bidirectional character handling. Profiles
   for iSCSI, Kerberos 5, Nameprep, SASL and XMPP are included.
   Punycode and ASCII Compatible Encoding (ACE) via IDNA are
   supported.

   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 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. Libidn is written in C and (parts of) the API is
   accessible from C, C++, Emacs Lisp, Python and Java.
     _________________________________________________________

2.1. Getting Started

   This manual documents the library programming interface. All
   functions and data types provided by the library are
   explained.

   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 (Chapter 8), and then only
   read up those parts of the interface which are unclear.
     _________________________________________________________

2.2. 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 the GNU Lesser General Public License.

   It's thread-safe
          No global state is kept in the library.

   It's portable
          It should work on all Unix like operating systems,
          including Windows.
     _________________________________________________________

2.3. Supported Platforms

   Libidn has at some point in time been tested on the following
   platforms.

    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. RedHat Linux 7.2 GCC 2.96 and GNU Make.
       alphaev6-unknown-linux-gnu, alphaev67-unknown-linux-gnu,
       ia64-unknown-linux-gnu.
    8. RedHat Linux 8.0 GCC 3.2 and GNU Make. i686-pc-linux-gnu.
    9. RedHat Advanced Server 2.1 GCC 2.96 and GNU Make.
       i686-pc-linux-gnu.
   10. Slackware Linux 8.0.01 GCC 2.95.3 and GNU Make.
       i686-pc-linux-gnu.
   11. Mandrake Linux 9.0 GCC 3.2 and GNU Make.
       i686-pc-linux-gnu.
   12. IRIX 6.5 MIPS C compiler, IRIX Make. mips-sgi-irix6.5.
   13. AIX 4.3.2 IBM C for AIX compiler, AIX Make.
       rs6000-ibm-aix4.3.2.0.
   14. Microsoft Windows 2000 (Cygwin) GCC 3.2, GNU make.
       i686-pc-cygwin.
   15. HP-UX 11 HP-UX C compiler and HP Make. ia64-hp-hpux11.22,
       hppa2.0w-hp-hpux11.11.
   16. SUN Solaris 2.8 Sun WorkShop Compiler C 6.0 and SUN Make.
       sparc-sun-solaris2.8.
   17. SUN Solaris 2.9 Sun Forte Developer 7 C compiler and GNU
       Make. sparc-sun-solaris2.9.
   18. NetBSD 1.6 GCC 2.95.3 and GNU Make.
       alpha-unknown-netbsd1.6, i386-unknown-netbsdelf1.6.
   19. OpenBSD 3.1 and 3.2 GCC 2.95.3 and GNU Make.
       alpha-unknown-openbsd3.1, i386-unknown-openbsd3.1.
   20. 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.
   21. MacOS X 10.2 Server Edition GCC 3.1 and GNU Make.
       powerpc-apple-darwin6.5.

   If you use Libidn on, or port Libidn to, a new platform please
   report it to the author.
     _________________________________________________________

2.4. 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
Drottningholmsv. 70
112 42 Stockholm
Sweden

E-mail: simon@josefsson.org

   If your company provide support related to GNU Libidn and
   would like to be mentioned here, contact the author (Section
   2.6).
     _________________________________________________________

2.5. Downloading and Installing

   The package can be downloaded from several places, including
   http://josefsson.org/libidn/releases/. The latest version is
   stored in a file, e.g., libidn-0.3.5.tar.gz where the 0.3.5
   indicate the highest version number.

   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 http://josefsson.org/libidn/releases/libidn-0.3.5.tar.gz
$ tar xfz libidn-0.3.5.tar.gz
$ cd libidn-0.3.5/
$ ./configure
...
$ make
...
$ make install
...

   After that Libidn should be properly installed and ready for
   use.
     _________________________________________________________

2.6. 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@gnu.org
     _________________________________________________________

2.7. 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 (Section 2.6). 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 ().
       If you normally code using another coding standard, there
       is no problem, but you should use indent to reformat the
       code () 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.
     _________________________________________________________

Chapter 3. 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 (Chapter 8).
     _________________________________________________________

3.1. 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
          the same name prefixes with one prepended underscore
          are reserved for internal use and should never be used
          by an application.

   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 the same
          name prefixes with one prepended underscore are
          reserved for internal use and should never be used by
          an application.

   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 the same name prefixes with
          one prepended underscore are reserved for internal use
          and should never be used by an application.
     _________________________________________________________

3.2. Initialization

   Libidn is stateless and does not need any initialization.
     _________________________________________________________

3.3. 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.

   const char * stringprep_check_version (const char *
   req_version) req_version: Required version number, or NULL.

   Check that the 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(1);
    }
     _________________________________________________________

3.4. 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' libarary.
   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`
     _________________________________________________________

3.5. Autoconf tests

   If you work on a project that uses Autoconf () to help find
   installed libraries, the suggestions in the previous section
   are not the entire story. There are a few methods to detect
   and incorporate Libidn into your Autoconf based package.
     _________________________________________________________

3.5.1. Autoconf test via pkg-config

   If your audience is a typical GNU/Linux desktop, you can often
   assume they have the pkg-config tool installed, in which you
   can use its Autoconf M4 macro to find and set up your package
   for use with Shishi. The following illustrate this scenario.

AC_ARG_ENABLE(idn,
        AC_HELP_STRING([--disable-idn],
                       [Don't use Libidn]),
        libidn=$enableval)
if test "$libidn" != "no" ; then
        PKG_CHECK_MODULES(LIBIDN, libidn >= 0.0.0,
                        [libidn=yes],
                        [libidn=no])
        if test "$libidn" != "yes" ; then
                libidn=no
                AC_MSG_WARN([Libidn not found])
        else
                libidn=yes
                AC_DEFINE(USE_LIBIDN, 1, [Define to 1 if you want Libid
n.])
        fi
fi
AC_MSG_CHECKING([if Libidn should be used])
AC_MSG_RESULT($libidn)
     _________________________________________________________

3.5.2. Standalone Autoconf test

   The following illustrate a standalone autconf test, that work
   regardless of if your project Libtool () or not. It is the
   most portable solution, and is recommended.

AC_CHECK_HEADER(idna.h,
        AC_CHECK_LIB(idn, stringprep_check_version,
                [libidn=yes AC_SUBST(SHISHI_LIBS, -lidn)],
                libidn=no),
        kerberos5=no)
AC_ARG_ENABLE(idn, AC_HELP_STRING([--disable-idn], [Don't use Libidn]),
        libidn=$enableval)
if test "$libidn" != "no" ; then
        AC_DEFINE(USE_LIBIDN, 1, [Define to 1 if you want Libidn.])
else
        AC_MSG_WARN([Libidn not found])
fi
AC_MSG_CHECKING([if Libidn should be used])
AC_MSG_RESULT($libidn)
     _________________________________________________________

Chapter 4. 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.
     _________________________________________________________

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. Unicode Encoding Transformation

   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.

   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.

   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.

   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 freed with free(). If an error occurs, NULL
   will be returned and error set.

   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, assuming valid UTF-8 input. This
   function does no error checking on the input.

   Return value: a pointer to a newly allocated UCS-4 string.
   This value must be freed with free().
     _________________________________________________________

4.3. Unicode Normalization

   uint32_t * stringprep_ucs4_nfkc_normalize (uint32_t * str,
   ssize_t len) str: a Unicode string.

   len: length of str array, or -1 if str is nul-terminated.

   Converts UCS4 string into UTF-8 and runs
   stringprep_utf8_nfkc_normalize().

   Return value: a newly allocated Unicode string, that is the
   NFKC normalized form of str.

   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.
     _________________________________________________________

4.4. Character Set Conversion

   const char * stringprep_locale_charset ( void) Find out system
   locale charset.

   Note that this function return what it believe the SYSTEM is
   using as a locale, not what locale the program is currently in
   (modified, e.g., by a setlocale(LC_CTYPE, "ISO-8859-1")). The
   reason is that data read from argv[], stdin etc comes from the
   system, and is more likely to be encoded using the system
   locale than the program locale.

   You can set the environment variable CHARSET to override the
   value returned. Note that this function caches the result, so
   you will have to modify CHARSET before calling (even
   indirectly) any stringprep functions, e.g., by setting it when
   invoking the application.

   Return value: Return the character set used by the system
   locale. It will never return NULL, but use "ASCII" as a
   fallback.

   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.

   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.

   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.
     _________________________________________________________

Chapter 5. 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.
     _________________________________________________________

5.1. Header file stringprep.h

   To use the functions explained in this chapter, you need to
   include the file stringprep.h using:

#include <stringprep.h>
     _________________________________________________________

5.2. 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.
     _________________________________________________________

5.3. Return Codes

   All functions return a code of the Stringprep_rc enumerated
   type:

   Stringprep_rc STRINGPREP_OK = 0 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_rc STRINGPREP_CONTAINS_UNASSIGNED String contain
   unassigned Unicode code points, which is forbidden by the
   profile.

   Stringprep_rc STRINGPREP_CONTAINS_PROHIBITED String contain
   code points prohibited by the profile.

   Stringprep_rc STRINGPREP_BIDI_BOTH_L_AND_RAL String contain
   code points with conflicting bidirection category.

   Stringprep_rc STRINGPREP_BIDI_LEADTRAIL_NOT_RAL Leading and
   trailing character in string not of proper bidirectional
   category.

   Stringprep_rc STRINGPREP_BIDI_CONTAINS_PROHIBITED Contains
   prohibited code points detected by bidirectional code.

   Stringprep_rc STRINGPREP_TOO_SMALL_BUFFER Buffer handed to
   function was too small. This usually indicate a problem in the
   calling application.

   Stringprep_rc STRINGPREP_PROFILE_ERROR The stringprep profile
   was inconsistent. This usually indicate an internal error in
   the library.

   Stringprep_rc STRINGPREP_FLAG_ERROR The supplied flag
   conflicted with profile. This usually indicate a problem in
   the calling application.

   Stringprep_rc STRINGPREP_UNKNOWN_PROFILE The supplied profile
   name was not known to the library.

   Stringprep_rc STRINGPREP_NFKC_FAILED The Unicode NFKC
   operation failed. This usually indicate an internal error in
   the library.

   Stringprep_rc STRINGPREP_MALLOC_ERROR The malloc was out of
   memory. This is usually a fatal error.
     _________________________________________________________

5.4. Control 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_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_profile_flags STRINGPREP_NO_UNASSIGNED Make the
   library return with an error if string contains unassigned
   characters according to profile.
     _________________________________________________________

5.5. Core Functions

   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: stringprep profile flags, 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, or 0.

   The profile contain the 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.

   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: stringprep profile flags, 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, or 0.

   The profile contain the 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.

   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: stringprep profile flags, 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, or 0.

   The profile contain the 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.

   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: stringprep profile flags, 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, 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.
     _________________________________________________________

5.6. Stringprep Profile Macros

   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.

   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.

   int stringprep_kerberos5 (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
   Kerberos5 stringprep profile. Returns 0 iff successful, or an
   error code.

   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.

   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.

   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.
     _________________________________________________________

Chapter 6. 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.
     _________________________________________________________

6.1. Header file punycode.h

   To use the functions explained in this chapter, you need to
   include the file punycode.h using:

#include <punycode.h>
     _________________________________________________________

6.2. Return Codes

   All functions return a code of the Punycode_status enumerated
   type:

   Punycode_status PUNYCODE_SUCCESS = 0 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_status PUNYCODE_BAD_INPUT Input is invalid.

   Punycode_status PUNYCODE_BIG_OUTPUT Output would exceed the
   space provided.

   Punycode_status PUNYCODE_OVERFLOW Input needs wider integers
   to process.
     _________________________________________________________

6.3. Unicode Code Point Type

   The punycode function uses a special type to denote Unicode
   code points. It is guaranteed to always be a 32 bit unsigned
   integer.

   uint32_t punycode_uint A unsigned integer that hold Unicode
   code points.
     _________________________________________________________

6.4. 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:

   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.

   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.
     _________________________________________________________

Chapter 7. 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.
     _________________________________________________________

7.1. Header file idna.h

   To use the functions explained in this chapter, you need to
   include the file idna.h using:

#include <idna.h>
     _________________________________________________________

7.2. Return Codes

   All functions return a exit code:

   Idna_rc IDNA_SUCCESS = 0 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_rc IDNA_STRINGPREP_ERROR Error during string preparation.

   Idna_rc IDNA_PUNYCODE_ERROR Error during punycode operation.

   Idna_rc IDNA_CONTAINS_NON_LDH For IDNA_USE_STD3_ASCII_RULES,
   indicate that the string contains non-LDH ASCII characters.

   Idna_rc IDNA_CONTAINS_MINUS For IDNA_USE_STD3_ASCII_RULES,
   indicate that the string contains a leading or trailing
   hyphen-minus (U+002D).

   Idna_rc IDNA_INVALID_LENGTH The final output string is not
   within the (inclusive) range 1 to 63 characters.

   Idna_rc IDNA_NO_ACE_PREFIX The string does not contain the ACE
   prefix (for ToUnicode).

   Idna_rc IDNA_ROUNDTRIP_VERIFY_ERROR The ToASCII operation on
   output string does not equal the input.

   Idna_rc IDNA_CONTAINS_ACE_PREFIX The input contains the ACE
   prefix (for ToASCII).

   Idna_rc IDNA_ICONV_ERROR Could not convert string in locale
   encoding.

   Idna_rc IDNA_MALLOC_ERROR Could not allocate buffer (this is
   typically a fatal error).
     _________________________________________________________

7.3. Control Flags

   The IDNA flags parameter can take on the following values, or
   a bit-wise inclusive or of any subset of the parameters:

   Idna_flags IDNA_ALLOW_UNASSIGNED Allow unassigned Unicode code
   points.

   Idna_flags IDNA_USE_STD3_ASCII_RULES Check output to make sure
   it is a STD3 conforming host name.
     _________________________________________________________

7.4. Prefix String

   #define IDNA_ACE_PREFIX String with the official IDNA prefix,
   xn--.
     _________________________________________________________

7.5. 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 deallocating)
   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
   deallocated 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:

   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: IDNA flags, 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 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 error code.

   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: IDNA flags, 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 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 ToUnicode output never contains more code points than its
   input. 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 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.
     _________________________________________________________

7.6. Simplified ToASCII Interface

   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: IDNA flags, 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.

   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: IDNA flags, 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.

   int idna_to_ascii_lz (const char * input, char ** output, int
   flags) input: zero terminated input UTF-8 string.

   output: pointer to newly allocated output string.

   flags: IDNA flags, 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.
     _________________________________________________________

7.7. Simplified ToUnicode Interface

   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: IDNA flags, 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.

   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: IDNA flags, 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.

   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: IDNA flags, 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.

   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: IDNA flags, 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.

   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: IDNA flags, 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.
     _________________________________________________________

Chapter 8. Examples

   This chapter contains example code which illustrate how
   `Libidn' can be used when writing your own application.
     _________________________________________________________

8.1. Example 1

   This example demonstrates how the stringprep functions are
   used.
/* example.c    Example code showing how to use stringprep().
 * Copyright (C) 2002, 2003  Simon Josefsson
 *
 * This file is part of GNU Libidn.
 *
 * GNU Libidn is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * GNU Libidn 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with GNU Libidn; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
  USA
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#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 (int argc, char *argv[])
{
  char buf[BUFSIZ];
  char *p;
  int rc;
  size_t i;

  printf ("Input string encoded as `%s': ", stringprep_locale_charset (
));
  fflush (stdout);
  fgets (buf, BUFSIZ, stdin);

  printf ("Before locale2utf8 (length %d): ", strlen (buf));
  for (i = 0; i < strlen (buf); i++)
    printf ("%02x ", 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 %d): ", strlen (buf));
  for (i = 0; i < strlen (buf); i++)
    printf ("%02x ", buf[i] & 0xFF);
  printf ("\n");

  rc = stringprep (buf, BUFSIZ, 0, stringprep_nameprep);
  if (rc != STRINGPREP_OK)
    printf ("Stringprep failed with rc %d...\n", rc);
  else
    {
      printf ("After stringprep (length %d): ", strlen (buf));
      for (i = 0; i < strlen (buf); i++)
        printf ("%02x ", buf[i] & 0xFF);
      printf ("\n");
    }

  return 0;
}
     _________________________________________________________

8.2. Example 2

   This example demonstrates how the punycode functions are used.
/* example2.c   Example code showing how to use punycode.
 * Copyright (C) 2002, 2003  Simon Josefsson
 * Copyright (C) 2002  Adam M. Costello
 *
 * This file is part of GNU Libidn.
 *
 * GNU Libidn is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * GNU Libidn 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with GNU Libidn; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
  USA
 *
 */

/*
 * 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 conta
in\n"
           "any characters from the ASCII repertoire, this test code\n"
           "supports only the printable characters, and needs the Punyc
ode\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];

  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: */

      fgets (input, ace_max_length + 2, stdin);
      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 war
ning */
}
     _________________________________________________________

8.3. 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, 2003  Simon Josefsson
 *
 * This file is part of GNU Libidn.
 *
 * GNU Libidn is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * GNU Libidn 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with GNU Libidn; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
  USA
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#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 libi
dn`
 * $ ./example3
 * Input domain encoded as `ISO-8859-1': www.rksmrgs.example
 * Read string (length 23): 77 77 77 2e 72 e4 6b 73 6d f6 72 67 e5 73 a
a 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 (int argc, char *argv[])
{
  char buf[BUFSIZ];
  char *p;
  int rc;
  size_t i;

  printf ("Input domain encoded as `%s': ", stringprep_locale_charset (
));
  fflush (stdout);
  fgets (buf, BUFSIZ, stdin);
  buf[strlen (buf) - 1] = '\0';

  printf ("Read string (length %d): ", strlen (buf));
  for (i = 0; i < strlen (buf); i++)
    printf ("%02x ", buf[i] & 0xFF);
  printf ("\n");

  rc = idna_to_ascii_lz (buf, &p, 0);
  if (rc != IDNA_SUCCESS)
    {
      printf ("ToASCII() failed... %d\n", rc);
      exit (1);
    }

  printf ("ACE label (length %d): '%s'\n", strlen (p), p);
  for (i = 0; i < strlen (p); i++)
    printf ("%02x ", p[i] & 0xFF);
  printf ("\n");

  free (p);

  return 0;
}
     _________________________________________________________

8.4. 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, 2003  Simon Josefsson
 *
 * This file is part of GNU Libidn.
 *
 * GNU Libidn is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * GNU Libidn 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with GNU Libidn; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
  USA
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#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 libi
dn`
 * $ ./example4
 * Input domain encoded as `ISO-8859-1': www.xn--rksmrgsa-0zap8p.exampl
e
 * Read string (length 33): 77 77 77 2e 78 6e 2d 2d 72 6b 73 6d 72 67 7
3 61 2d 30 7a 61 70 38 70 2e 65 78 61 6d 70 6c 65
 * ACE label (length 23): 'www.rksmrgsa.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 (int argc, char *argv[])
{
  char buf[BUFSIZ];
  char *p;
  int rc;
  size_t i;

  printf ("Input domain encoded as `%s': ", stringprep_locale_charset (
));
  fflush (stdout);
  fgets (buf, BUFSIZ, stdin);
  buf[strlen (buf) - 1] = '\0';

  printf ("Read string (length %d): ", strlen (buf));
  for (i = 0; i < strlen (buf); i++)
    printf ("%02x ", buf[i] & 0xFF);
  printf ("\n");

  rc = idna_to_unicode_lzlz (buf, &p, 0);
  if (rc != IDNA_SUCCESS)
    {
      printf ("ToUnicode() failed... %d\n", rc);
      exit (1);
    }

  printf ("ACE label (length %d): '%s'\n", strlen (p), p);
  for (i = 0; i < strlen (p); i++)
    printf ("%02x ", p[i] & 0xFF);
  printf ("\n");

  free (p);

  return 0;
}
     _________________________________________________________

Chapter 9. Invoking idn
     _________________________________________________________

9.1. Name

   GNU Libidn (idn) - Internationalized Domain Names command line
   tool
     _________________________________________________________

9.2. 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.
     _________________________________________________________

9.3. 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)

  -u, --idna-to-unicode    Convert from ACE according to IDNA

      --allow-unassigned   Toggle IDNA AllowUnassigned flag  (default=o
ff)

      --usestd3asciirules  Toggle IDNA UseSTD3ASCIIRules flag  (default
=off)

  -p, --profile=STRING     Use specified stringprep profile instead

  Valid stringprep profiles are 'Nameprep', 'KRBprep', 'Nodeprep',
  'Resourceprep', 'plain', 'trace', 'SASLprep', and 'ISCSIprep'.

      --debug              Print debugging information  (default=off)

      --quiet              Silent operation  (default=off)
     _________________________________________________________

9.4. 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
...
     _________________________________________________________

9.5. 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 cha
racter.
rksmrgs
xn--rksmrgs-5wao1o
jas@latte:~$

   Reading input from command line, and disabling copyright and
   license information:

jas@latte:~$ idn --quiet rksmrgs blbrgrd
xn--rksmrgs-5wao1o
xn--blbrgrd-fxak7p
jas@latte:~$

   Accessing a specific StringPrep profile directly:

jas@latte:~$ idn --quiet --profile=SASLprep --stringprep tet
teta
jas@latte:~$
     _________________________________________________________

Chapter 10. 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.
     _________________________________________________________

10.1. Punycode Emacs API

   punycode-program Name of the GNU Libidn idn application. The
   default is idn. This variable can be customized.

   punycode-environment List of environment variable definitions
   prepended to process-environment. The default is
   ("CHARSET=UTF-8"). This variable can be customized.

   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.

   punycode-decode-parameters Parameters passed to
   punycode-program to invoke punycode decoding mode. The default
   is ("--quiet" "--punycode-decode"). This variable can be
   customized.

   punycode-encode string Returns a Punycode encoding of the
   string, after converting the input into UTF-8.

   punycode-decode string Returns a possibly multibyte string
   which is the decoding of the string which is a punycode
   encoded string.
     _________________________________________________________

10.2. IDNA Emacs API

   idna-program Name of the GNU Libidn idn application. The
   default is idn. This variable can be customized.

   idna-environment List of environment variable definitions
   prepended to process-environment. The default is
   ("CHARSET=UTF-8"). This variable can be customized.

   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.

   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.

   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.

   idna-to-unicode string Returns a possibly multibyte string
   which is the output of the IDNA ToUnicode operation computed
   on the input string.
     _________________________________________________________

Chapter 11. Acknowledgements

   The punycode code was taken from the IETF IDN Punycode
   specification, by Adam M. Costello.

   Some functions (see nfkc.c and toutf8.c) has been borrowed
   from GLib downloaded from www.gtk.org.

   Several people reported bugs, sent patches or suggested
   improvements, see the file THANKS.
     _________________________________________________________

Concept Index

A

   AIX, see Section 2.3
   Autoconf tests, see Section 3.5
     _________________________________________________________

C

   command line, see Chapter 9
   Compiling your application, see Section 3.4
   Configure tests, see Section 3.5
   Contributing, see Section 2.7
     _________________________________________________________

D

   Debian, see Section 2.3
   Download, see Section 2.5
     _________________________________________________________

E

   Examples, see Chapter 8
     _________________________________________________________

F

   FreeBSD, see Section 2.3
     _________________________________________________________

H

   Hacking, see Section 2.7
   HP-UX, see Section 2.3
     _________________________________________________________

I

   idn, see Chapter 9
   IDNA Functions, see Chapter 7
   Installation, see Section 2.5
   invoking idn, see Chapter 9
   IRIX, see Section 2.3
     _________________________________________________________

M

   MacOS X, see Section 2.3
   Mandrake, see Section 2.3
     _________________________________________________________

N

   NetBSD, see Section 2.3
     _________________________________________________________

O

   OpenBSD, see Section 2.3
     _________________________________________________________

P

   Punycode Functions, see Chapter 6
     _________________________________________________________

R

   RedHat, see Section 2.3
   RedHat Advanced Server, see Section 2.3
   Reporting Bugs, see Section 2.6
     _________________________________________________________

S

   Solaris, see Section 2.3
   Stringprep Functions, see Chapter 5
   SuSE, see Section 2.3
   SuSE Linux, see Section 2.3
     _________________________________________________________

T

   Tru64, see Section 2.3
     _________________________________________________________

U

   Utility Functions, see Chapter 4
     _________________________________________________________

W

   Windows, see Section 2.3
     _________________________________________________________

Function and Variable Index

I

   idna-to-ascii, see Chapter 10
   idna-to-unicode, see Chapter 10
   idna_to_ascii_4i, see Chapter 7
   idna_to_ascii_4z, see Chapter 7
   idna_to_ascii_8z, see Chapter 7
   idna_to_ascii_lz, see Chapter 7
   idna_to_unicode_44i, see Chapter 7
   idna_to_unicode_4z4z, see Chapter 7
   idna_to_unicode_8z4z, see Chapter 7
   idna_to_unicode_8z8z, see Chapter 7
   idna_to_unicode_8zlz, see Chapter 7
   idna_to_unicode_lzlz, see Chapter 7
     _________________________________________________________

P

   punycode-decode, see Chapter 10
   punycode-encode, see Chapter 10
   punycode_decode, see Chapter 6
   punycode_encode, see Chapter 6
     _________________________________________________________

S

   stringprep, see Chapter 5
   stringprep_4i, see Chapter 5
   stringprep_4zi, see Chapter 5
   stringprep_check_version, see Section 3.3
   stringprep_convert, see Chapter 4
   stringprep_iscsi, see Chapter 5
   stringprep_kerberos5, see Chapter 5
   stringprep_locale_charset, see Chapter 4
   stringprep_locale_to_utf8, see Chapter 4
   stringprep_nameprep_no_unassigned, see Chapter 5
   stringprep_plain, see Chapter 5
   stringprep_profile, see Chapter 5
   stringprep_ucs4_nfkc_normalize, see Chapter 4
   stringprep_ucs4_to_utf8, see Chapter 4
   stringprep_unichar_to_utf8, see Chapter 4
   stringprep_utf8_nfkc_normalize, see Chapter 4
   stringprep_utf8_to_locale, see Chapter 4
   stringprep_utf8_to_ucs4, see Chapter 4
   stringprep_utf8_to_unichar, see Chapter 4
   stringprep_xmpp_nodeprep, see Chapter 5
   stringprep_xmpp_resourceprep, see Chapter 5
     _________________________________________________________

Appendix A. Copying The Library

   Version 2.1, February 1999
Copyright  1991, 1999 Free Software Foundation, Inc.
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

[This is the first released version of the Lesser GPL.  It also counts
as the successor of the GNU Library Public License, version 2, hence th
e
version number 2.1.]
     _________________________________________________________

A.1. Preamble

   The licenses for most software are designed to take away your
   freedom to share and change it. By contrast, the GNU General
   Public Licenses are intended to guarantee your freedom to
   share and change free software--to make sure the software is
   free for all its users.

   This license, the Lesser General Public License, applies to
   some specially designated software--typically libraries--of
   the Free Software Foundation and other authors who decide to
   use it. You can use it too, but we suggest you first think
   carefully about whether this license or the ordinary General
   Public License is the better strategy to use in any particular
   case, based on the explanations below.

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one line to give the library's name and an idea of what it does.
Copyright (C) year  name of author

This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published b
y
the Free Software Foundation; either version 2.1 of the License, or (at
your option) any later version.

This library 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
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You should have received a copy of the GNU Lesser General Public
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signature of Ty Coon, 1 April 1990
Ty Coon, President of Vice

   That's all there is to it!
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Appendix B. Copying This Manual

B.1. GNU Free Documentation License

   Version 1.1, March 2000
Copyright  2000 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA  02111-1307, USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

    1. PREAMBLE
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       public-standard network protocols. If you use the latter
       option, you must take reasonably prudent steps, when you
       begin distribution of Opaque copies in quantity, to ensure
       that this Transparent copy will remain thus accessible at
       the stated location until at least one year after the last
       time you distribute an Opaque copy (directly or through
       your agents or retailers) of that edition to the public.
       It is requested, but not required, that you contact the
       authors of the Document well before redistributing any
       large number of copies, to give them a chance to provide
       you with an updated version of the Document.
    5. MODIFICATIONS
       You may copy and distribute a Modified Version of the
       Document under the conditions of sections 2 and 3 above,
       provided that you release the Modified Version under
       precisely this License, with the Modified Version filling
       the role of the Document, thus licensing distribution and
       modification of the Modified Version to whoever possesses
       a copy of it. In addition, you must do these things in the
       Modified Version:
         A. Use in the Title Page (and on the covers, if any) a
            title distinct from that of the Document, and from
            those of previous versions (which should, if there
            were any, be listed in the History section of the
            Document). You may use the same title as a previous
            version if the original publisher of that version
            gives permission.
         B. List on the Title Page, as authors, one or more
            persons or entities responsible for authorship of the
            modifications in the Modified Version, together with
            at least five of the principal authors of the
            Document (all of its principal authors, if it has
            less than five).
         C. State on the Title page the name of the publisher of
            the Modified Version, as the publisher.
         D. Preserve all the copyright notices of the Document.
         E. Add an appropriate copyright notice for your
            modifications adjacent to the other copyright
            notices.
         F. Include, immediately after the copyright notices, a
            license notice giving the public permission to use
            the Modified Version under the terms of this License,
            in the form shown in the Addendum below.
         G. Preserve in that license notice the full lists of
            Invariant Sections and required Cover Texts given in
            the Document's license notice.
         H. Include an unaltered copy of this License.
         I. Preserve the section entitled "History", and its
            title, and add to it an item stating at least the
            title, year, new authors, and publisher of the
            Modified Version as given on the Title Page. If there
            is no section entitled "History" in the Document,
            create one stating the title, year, authors, and
            publisher of the Document as given on its Title Page,
            then add an item describing the Modified Version as
            stated in the previous sentence.
         J. Preserve the network location, if any, given in the
            Document for public access to a Transparent copy of
            the Document, and likewise the network locations
            given in the Document for previous versions it was
            based on. These may be placed in the "History"
            section. You may omit a network location for a work
            that was published at least four years before the
            Document itself, or if the original publisher of the
            version it refers to gives permission.
         K. In any section entitled "Acknowledgments" or
            "Dedications", preserve the section's title, and
            preserve in the section all the substance and tone of
            each of the contributor acknowledgments and/or
            dedications given therein.
         L. Preserve all the Invariant Sections of the Document,
            unaltered in their text and in their titles. Section
            numbers or the equivalent are not considered part of
            the section titles.
         M. Delete any section entitled "Endorsements". Such a
            section may not be included in the Modified Version.
         N. Do not retitle any existing section as "Endorsements"
            or to conflict in title with any Invariant Section.
       If the Modified Version includes new front-matter sections
       or appendices that qualify as Secondary Sections and
       contain no material copied from the Document, you may at
       your option designate some or all of these sections as
       invariant. To do this, add their titles to the list of
       Invariant Sections in the Modified Version's license
       notice. These titles must be distinct from any other
       section titles.
       You may add a section entitled "Endorsements", provided it
       contains nothing but endorsements of your Modified Version
       by various parties--for example, statements of peer review
       or that the text has been approved by an organization as
       the authoritative definition of a standard.
       You may add a passage of up to five words as a Front-Cover
       Text, and a passage of up to 25 words as a Back-Cover
       Text, to the end of the list of Cover Texts in the
       Modified Version. Only one passage of Front-Cover Text and
       one of Back-Cover Text may be added by (or through
       arrangements made by) any one entity. If the Document
       already includes a cover text for the same cover,
       previously added by you or by arrangement made by the same
       entity you are acting on behalf of, you may not add
       another; but you may replace the old one, on explicit
       permission from the previous publisher that added the old
       one.
       The author(s) and publisher(s) of the Document do not by
       this License give permission to use their names for
       publicity for or to assert or imply endorsement of any
       Modified Version.
    6. COMBINING DOCUMENTS
       You may combine the Document with other documents released
       under this License, under the terms defined in section 4
       above for modified versions, provided that you include in
       the combination all of the Invariant Sections of all of
       the original documents, unmodified, and list them all as
       Invariant Sections of your combined work in its license
       notice.
       The combined work need only contain one copy of this
       License, and multiple identical Invariant Sections may be
       replaced with a single copy. If there are multiple
       Invariant Sections with the same name but different
       contents, make the title of each such section unique by
       adding at the end of it, in parentheses, the name of the
       original author or publisher of that section if known, or
       else a unique number. Make the same adjustment to the
       section titles in the list of Invariant Sections in the
       license notice of the combined work.
       In the combination, you must combine any sections entitled
       "History" in the various original documents, forming one
       section entitled "History"; likewise combine any sections
       entitled "Acknowledgments", and any sections entitled
       "Dedications". You must delete all sections entitled
       "Endorsements."
    7. COLLECTIONS OF DOCUMENTS
       You may make a collection consisting of the Document and
       other documents released under this License, and replace
       the individual copies of this License in the various
       documents with a single copy that is included in the
       collection, provided that you follow the rules of this
       License for verbatim copying of each of the documents in
       all other respects.
       You may extract a single document from such a collection,
       and distribute it individually under this License,
       provided you insert a copy of this License into the
       extracted document, and follow this License in all other
       respects regarding verbatim copying of that document.
    8. AGGREGATION WITH INDEPENDENT WORKS
       A compilation of the Document or its derivatives with
       other separate and independent documents or works, in or
       on a volume of a storage or distribution medium, does not
       as a whole count as a Modified Version of the Document,
       provided no compilation copyright is claimed for the
       compilation. Such a compilation is called an "aggregate",
       and this License does not apply to the other
       self-contained works thus compiled with the Document, on
       account of their being thus compiled, if they are not
       themselves derivative works of the Document.
       If the Cover Text requirement of section 3 is applicable
       to these copies of the Document, then if the Document is
       less than one quarter of the entire aggregate, the
       Document's Cover Texts may be placed on covers that
       surround only the Document within the aggregate. Otherwise
       they must appear on covers around the whole aggregate.
    9. TRANSLATION
       Translation is considered a kind of modification, so you
       may distribute translations of the Document under the
       terms of section 4. Replacing Invariant Sections with
       translations requires special permission from their
       copyright holders, but you may include translations of
       some or all Invariant Sections in addition to the original
       versions of these Invariant Sections. You may include a
       translation of this License provided that you also include
       the original English version of this License. In case of a
       disagreement between the translation and the original
       English version of this License, the original English
       version will prevail.
   10. TERMINATION
       You may not copy, modify, sublicense, or distribute the
       Document except as expressly provided for under this
       License. Any other attempt to copy, modify, sublicense or
       distribute the Document is void, and will automatically
       terminate your rights under this License. However, parties
       who have received copies, or rights, from you under this
       License will not have their licenses terminated so long as
       such parties remain in full compliance.
   11. FUTURE REVISIONS OF THIS LICENSE
       The Free Software Foundation may publish new, revised
       versions of the GNU Free Documentation License from time
       to time. Such new versions will be similar in spirit to
       the present version, but may differ in detail to address
       new problems or concerns. See
       http://www.gnu.org/copyleft/.
       Each version of the License is given a distinguishing
       version number. If the Document specifies that a
       particular numbered version of this License "or any later
       version" applies to it, you have the option of following
       the terms and conditions either of that specified version
       or of any later version that has been published (not as a
       draft) by the Free Software Foundation. If the Document
       does not specify a version number of this License, you may
       choose any version ever published (not as a draft) by the
       Free Software Foundation.
     _________________________________________________________

B.2. How to use this License for your documents

   To use this License in a document you have written, include a
   copy of the License in the document and put the following
   copyright and license notices just after the title page:

  Copyright (C)  year  your name.
  Permission is granted to copy, distribute and/or modify this document
  under the terms of the GNU Free Documentation License, Version 1.1
  or any later version published by the Free Software Foundation;
  with the Invariant Sections being list their titles, with the
  Front-Cover Texts being list, and with the Back-Cover Texts
  being list.  A copy of the license is included in the section
  entitled ``GNU Free Documentation License''.


   If you have no Invariant Sections, write "with no Invariant
   Sections" instead of saying which ones are invariant. If you
   have no Front-Cover Texts, write "no Front-Cover Texts"
   instead of "Front-Cover Texts being list"; likewise for
   Back-Cover Texts.

   If your document contains nontrivial examples of program code,
   we recommend releasing these examples in parallel under your
   choice of free software license, such as the GNU General
   Public License, to permit their use in free software.
