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 no Invariant Sections, 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."
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. It is available under the GNU Lesser General Public License. Currently the iSCSI, Kerberos 5, Nameprep, SASL and XMPP Stringprep profiles are supported.
The library contains a generic Stringprep implementation (including Unicode 3.2 NFKC normalization, table mapping of characters, and Bidirectional Character handling), a few Stringprep profiles, and an implementation of the functionality defined by Punycode and IDNA.
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. Each stringprep profile has a corresponding CPP macro. 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 forthcoming network applications to process user names and passwords before they are input to cryptographic operations. Libidn can be built into GNU Libc to enable a new getaddrinfo() flag for system-wide IDN processing.
GNU Libidn is developed for the GNU/Linux system, but runs on over 20 Unix platforms (including Solaris, IRIX, AIX, and Tru64) and Windows.
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 (see Examples), and then only read up those parts of the interface which are unclear.
This library might have a couple of advantages over other libraries doing a similar job.
Libidn has at some point in time been tested on the following platforms.
GCC 2.95.4 and GNU Make. This is the main development platform.
alphaev67-unknown-linux-gnu, alphaev6-unknown-linux-gnu,
hppa64-unknown-linux-gnu, i686-pc-linux-gnu,
ia64-unknown-linux-gnu.
Tru64 UNIX C compiler and Tru64 Make. alphaev67-dec-osf5.1,
alphaev68-dec-osf5.1.
GCC 2.96 and GNU Make. alphaev6-unknown-linux-gnu,
alphaev67-unknown-linux-gnu.
GCC 3.0 and GNU Make. ia64-unknown-linux-gnu.
GCC 2.96 and GNU Make. alphaev6-unknown-linux-gnu,
alphaev67-unknown-linux-gnu, ia64-unknown-linux-gnu.
GCC 3.2 and GNU Make. i686-pc-linux-gnu.
GCC 2.96 and GNU Make. i686-pc-linux-gnu.
GCC 2.95.3 and GNU Make. i686-pc-linux-gnu.
GCC 3.2 and GNU Make. i686-pc-linux-gnu.
MIPS C compiler, IRIX Make. mips-sgi-irix6.5.
IBM C for AIX compiler, AIX Make. rs6000-ibm-aix4.3.2.0.
GCC 3.2, GNU make. i686-pc-cygwin.
HP-UX C compiler and HP Make. ia64-hp-hpux11.22,
hppa2.0w-hp-hpux11.11.
Sun WorkShop Compiler C 6.0 and SUN Make. sparc-sun-solaris2.8.
GCC 2.95.3 and GNU Make. alpha-unknown-netbsd1.6,
i386-unknown-netbsdelf1.6.
GCC 2.95.3 and GNU Make. alpha-unknown-openbsd3.1,
i386-unknown-openbsd3.1.
GCC 2.95.4 and GNU Make. alpha-unknown-freebsd4.7,
i386-unknown-freebsd4.7.
If you use Libidn on, or port Libidn to, a new platform please report it to the author.
If you think you have found a bug in Libidn, please investigate it and report it.
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.orgTo 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 (see Examples).
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:
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.
This header file uses the same namespace as the main stringprep.h
header file.
This header file uses the same namespace as the main stringprep.h
header file.
This header file uses the same namespace as the main stringprep.h
header file.
This header file uses the same namespace as the main stringprep.h
header file.
This header file uses the same namespace as the main stringprep.h
header file.
This header file uses the same namespace as the main stringprep.h
header file.
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.
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.
Libidn is stateless and does not need any initialization.
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) | Function |
|
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 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);
}
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`
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.
| STRINGPREP_NO_NFKC | Enumerated type of Stringprep_profile_flags |
| STRINGPREP_NO_NFKC disables the NFKC normalization, as well as selecting the non-NFKC case folding tables. Usually the profile specifies BIDI and NFKC settings. |
| STRINGPREP_NO_BIDI | Enumerated type of Stringprep_profile_flags |
| STRINGPREP_NO_BIDI disables the BIDI step. Usually the profile specifies BIDI and NFKC settings. |
| STRINGPREP_NO_UNASSIGNED | Enumerated type of Stringprep_profile_flags |
| STRINGPREP_NO_UNASSIGNED causes stringprep() abort with an error if string contains unassigned characters according to profile. |
| int stringprep (char * in, size_t maxlen, int flags, Stringprep_profile * profile) | Function |
|
in: input/ouput array with string to prepare. maxlen: maximum length of input/output array. flags: optional stringprep profile flags. profile: pointer to stringprep profile to use. Prepare the input UTF-8 string according to the stringprep profile.
Normally application programmers use stringprep profile macros such
as Since the stringprep operation can expand the string, Returns 0 iff successful, or an error code. |
| unsigned long stringprep_utf8_to_unichar (const char * p) | Function |
|
p: a pointer to Unicode character encoded as UTF-8 Converts a sequence of bytes encoded as UTF-8 to a Unicode character.
If the resulting character |
| int stringprep_unichar_to_utf8 (unsigned long c, char * outbuf) | Function |
|
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 Converts a single character to UTF-8. number of bytes written |
| unsigned long * stringprep_utf8_to_ucs4 (const char * str, ssize_t len, size_t * items_written) | Function |
|
str: a UTF-8 encoded string len: the maximum length of 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. a pointer to a newly allocated UCS-4 string.
This value must be freed with |
| char * stringprep_ucs4_to_utf8 (const unsigned long * str, ssize_t len, size_t * items_read, size_t * items_written) | Function |
|
str: a UCS-4 encoded string len: the maximum length of 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. a pointer to a newly allocated UTF-8 string.
This value must be freed with |
| char * stringprep_utf8_nfkc_normalize (const char * str, ssize_t len) | Function |
|
str: a UTF-8 encoded string. len: length of 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. You
should generally call 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. a newly allocated string, that is the
NFKC normalized form of |
| unsigned long * stringprep_ucs4_nfkc_normalize (unsigned long * str, ssize_t len) | Function |
|
str: a Unicode string. len: length of Converts UCS4 string into UTF-8 and runs
a newly allocated Unicode string, that is the NFKC
normalized form of |
| const char * stringprep_locale_charset ( void) | Function |
|
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) | Function |
|
str: input zero-terminated string. to_codeset: name of destination character set. from_codeset: name of origin character set, as used by Convert the string from one character set to another using the
system's Returns newly allocated zero-terminated string which
is |
| char * stringprep_locale_to_utf8 (const char * str) | Function |
|
str: input zero terminated string. Convert string encoded in the locale's character set into UTF-8 by
using Returns newly allocated zero-terminated string which
is |
| char * stringprep_utf8_to_locale (const char * str) | Function |
|
str: input zero terminated string. Convert string encoded in UTF-8 into the locale's character set by
using Returns newly allocated zero-terminated string which
is |
| int stringprep_nameprep_no_unassigned (char * in, int maxlen) | Function |
|
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 |
| int stringprep_iscsi (char * in, int maxlen) | Function |
|
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) | Function |
|
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) | Function |
|
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) | Function |
|
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) | Function |
|
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. |
| int stringprep_generic (char * in, int maxlen) | Function |
|
in: input/ouput array with string to prepare. maxlen: maximum length of input/output array. Prepare the input UTF-8 string according to a hypotetical "generic" stringprep profile. This is mostly used for debugging or when constructing new stringprep profiles. Returns 0 iff successful, or an error code. |
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). This document defines a general algorithm called Bootstring that 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 specified by this document, appropriate for IDNA.
| int punycode_encode (size_t input_length, const unsigned long input[], const unsigned char case_flags[], size_t * output_length, char output[]) | Function |
|
input_length: The input_length is the number of code points in the input. output_length: The output_length is an in/out argument: the caller passes in the maximum number of code points that it can receive, and on successful return it will contain the number of code points actually output. Converts Unicode to Punycode. 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, unsigned long output[], unsigned char case_flags[]) | Function |
|
input_length: The input_length is the number of code points in the input. output_length: The output_length is an in/out argument: the caller passes in the maximum number of code points that it can receive, and on successful return it will contain the actual number of code points output. Converts Punycode to Unicode. 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. On success, the decoder will never need to write an output_length greater than input_length, because of how the encoding is defined. |
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.
| int idna_to_ascii (const unsigned long * in, size_t inlen, char * out, int allowunassigned, int usestd3asciirules) | Function |
|
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. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. Returns 0 on success, or an error code. |
| int idna_to_unicode (const unsigned long * in, size_t inlen, unsigned long * out, size_t * outlen, int allowunassigned, int usestd3asciirules) | Function |
|
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. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. 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. |
| int idna_to_ascii_from_ucs4 (const unsigned long * input, char ** output, int allowunassigned, int usestd3asciirules) | Function |
|
input: zero terminated input Unicode string. output: pointer to newly allocated output string. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. Returns IDNA_SUCCESS on success, or error code. |
| int idna_ucs4_to_ace (const unsigned long * input, char ** output) | Function |
|
input: zero terminated input Unicode string. output: pointer to newly allocated output string. Convert UCS-4 domain name to ASCII string. The AllowUnassigned flag is false and std3asciirules flag is false. The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. This function is deprecated in favor of Returns IDNA_SUCCESS on success, or error code. |
| int idna_to_ascii_from_utf8 (const char * input, char ** output, int allowunassigned, int usestd3asciirules) | Function |
|
input: zero terminated input UTF-8 string. output: pointer to newly allocated output string. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. Returns IDNA_SUCCESS on success, or error code. |
| int idna_utf8_to_ace (const char * input, char ** output) | Function |
|
input: zero terminated input UTF-8 string. output: pointer to newly allocated output string. Convert UTF-8 domain name to ASCII string. The AllowUnassigned flag is false and std3asciirules flag is false. The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. This function is deprecated in favor of Returns IDNA_SUCCESS on success, or error code. |
| int idna_to_ascii_from_locale (const char * input, char ** output, int allowunassigned, int usestd3asciirules) | Function |
|
input: zero terminated input UTF-8 string. output: pointer to newly allocated output string. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. Returns IDNA_SUCCESS on success, or error code. |
| int idna_locale_to_ace (const char * input, char ** output) | Function |
|
input: zero terminated input UTF-8 string. output: pointer to newly allocated output string. Convert domain name in the locale's encoding to ASCII string. The AllowUnassigned flag is false and std3asciirules flag is false. The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. This function is deprecated in favor of Returns IDNA_SUCCESS on success, or error code. |
| int idna_to_unicode_ucs4_from_ucs4 (const unsigned long * input, unsigned long ** output, int allowunassigned, int usestd3asciirules) | Function |
|
input: zero-terminated Unicode string. output: pointer to newly allocated output Unicode string. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. Returns IDNA_SUCCESS on success, or error code. |
| int idna_ucs4ace_to_ucs4 (const unsigned long * input, unsigned long ** output) | Function |
|
input: zero-terminated Unicode string. output: pointer to newly allocated output Unicode string. Convert possibly ACE encoded domain name in UCS-4 format into a UCS-4 string. The AllowUnassigned flag is false and std3asciirules flag is false. The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. This function is deprecated in favor of
Returns IDNA_SUCCESS on success, or error code. |
| int idna_to_unicode_ucs4_from_utf8 (const char * input, unsigned long ** output, int allowunassigned, int usestd3asciirules) | Function |
|
input: zero-terminated UTF-8 string. output: pointer to newly allocated output Unicode string. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. Returns IDNA_SUCCESS on success, or error code. |
| int idna_utf8ace_to_ucs4 (const char * input, unsigned long ** output) | Function |
|
input: zero-terminated UTF-8 string. output: pointer to newly allocated output Unicode string. Convert possibly ACE encoded domain name in UTF-8 format into a UCS-4 string. The AllowUnassigned flag is false and std3asciirules flag is false. The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. This function is deprecated in favor of
Returns IDNA_SUCCESS on success, or error code. |
| int idna_to_unicode_utf8_from_utf8 (const char * input, char ** output, int allowunassigned, int usestd3asciirules) | Function |
|
input: zero-terminated UTF-8 string. output: pointer to newly allocated output UTF-8 string. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. Returns IDNA_SUCCESS on success, or error code. |
| int idna_utf8ace_to_utf8 (const char * input, char ** output) | Function |
|
input: zero-terminated UTF-8 string. output: pointer to newly allocated output UTF-8 string. Convert possibly ACE encoded domain name in UTF-8 format into a UTF-8 string. The AllowUnassigned flag is false and std3asciirules flag is false. The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. This function is deprecated in favor of
Returns IDNA_SUCCESS on success, or error code. |
| int idna_to_unicode_locale_from_utf8 (const char * input, char ** output, int allowunassigned, int usestd3asciirules) | Function |
|
input: zero-terminated UTF-8 string. output: pointer to newly allocated output string encoded in the current locale's character set. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. Convert possibly ACE encoded domain name in UTF-8 format into a string encoded in the current locale's character set. The The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. Returns IDNA_SUCCESS on success, or error code. |
| int idna_utf8ace_to_locale (const char * input, char ** output) | Function |
|
input: zero-terminated UTF-8 string. output: pointer to newly allocated output string encoded in the current locale's character set. Convert possibly ACE encoded domain name in UTF-8 format into a string encoded in the current locale's character set. The AllowUnassigned flag is false and std3asciirules flag is false. The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. This function is deprecated in favor of
Returns IDNA_SUCCESS on success, or error code. |
| int idna_to_unicode_locale_from_locale (const char * input, char ** output, int allowunassigned, int usestd3asciirules) | Function |
|
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. allowunassigned: whether to allow unassigned code points. usestd3asciirules: whether to check input for STD3 compliance. 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. Returns IDNA_SUCCESS on success, or error code. |
| int idna_localeace_to_locale (const char * input, char ** output) | Function |
|
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. Convert possibly ACE encoded domain name in the locale's character set into a string encoded in the current locale's character set. The AllowUnassigned flag is false and std3asciirules flag is false. The domain name may contain several labels, separated by dots. The output buffer must be deallocated by the caller. This function is deprecated in favor of
Returns IDNA_SUCCESS on success, or error code. |
This chapter contains example code which illustrate how `Libidn' can be used when writing your own application.
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_nameprep.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': ª
* 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;
}
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 from draft-ietf-idn-punycode-03.txt by
* Adam M. Costello.
*
* Disclaimer and license: Regarding this entire document or any
* portion of it (including the pseudocode and C code), the author
* makes no guarantees and is not responsible for any damage resulting
* from its use. The author grants irrevocable permission to anyone
* to use, modify, and distribute it in any way that does not diminish
* the rights of anyone else to use, modify, and distribute it,
* provided that redistributed derivative works do not contain
* misleading author or version information. Derivative works need
* not be licensed under similar terms.
*
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "punycode.h"
/* For testing, we'll just set some compile-time limits rather than */
/* use malloc(), and set a compile-time option rather than using a */
/* command-line option. */
enum
{
unicode_max_length = 256,
ace_max_length = 256
};
static void
usage (char **argv)
{
fprintf (stderr,
"\n"
"%s -e reads code points and writes a Punycode string.\n"
"%s -d reads a Punycode string and writes code points.\n"
"\n"
"Input and output are plain text in the native character set.\n"
"Code points are in the form u+hex separated by whitespace.\n"
"Although the specification allows Punycode strings to contain\n"
"any characters from the ASCII repertoire, this test code\n"
"supports only the printable characters, and needs the Punycode\n"
"string to be followed by a newline.\n"
"The case of the u in u+hex is the force-to-uppercase flag.\n",
argv[0], argv[0]);
exit (EXIT_FAILURE);
}
static void
fail (const char *msg)
{
fputs (msg, stderr);
exit (EXIT_FAILURE);
}
static const char too_big[] =
"input or output is too large, recompile with larger limits\n";
static const char invalid_input[] = "invalid input\n";
static const char overflow[] = "arithmetic overflow\n";
static const char io_error[] = "I/O error\n";
/* The following string is used to convert printable */
/* characters between ASCII and the native charset: */
static const char print_ascii[] =
"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n"
"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n"
" !\"#$%&'()*+,-./"
"0123456789:;<=>?"
"\x40""ABCDEFGHIJKLMNO"
"PQRSTUVWXYZ[\\]^_" "`abcdefghijklmno" "pqrstuvwxyz{|}~\n";
int
main (int argc, char **argv)
{
int 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')
{
unsigned long 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 > (unsigned long) -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;
unsigned long 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 warning */
}
This example demonstrates how the library is used to convert internationalized domain names into ASCII compatible names.
/* example3.c Example 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_locale_to_ace() */
/*
* Compiling using libtool and pkg-config is recommended:
*
* $ libtool cc -o example3 example3.c `pkg-config --cflags --libs libidn`
* $ ./example3
* Input domain encoded as `ISO-8859-1': www.räksmörgåsª.example
* Read string (length 23): 77 77 77 2e 72 e4 6b 73 6d f6 72 67 e5 73 aa 2e 65 78 61 6d 70 6c 65
* ACE label (length 33): 'www.xn--rksmrgsa-0zap8p.example'
* 77 77 77 2e 78 6e 2d 2d 72 6b 73 6d 72 67 73 61 2d 30 7a 61 70 38 70 2e 65 78 61 6d 70 6c 65
* $
*
*/
int
main (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_locale_to_ace (buf, &p);
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;
}
This example demonstrates how the library is used to convert ASCII compatible names to internationalized domain names.
/* example4.c Example 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_localeace_to_locale() */
/*
* Compiling using libtool and pkg-config is recommended:
*
* $ libtool cc -o example4 example4.c `pkg-config --cflags --libs libidn`
* $ ./example4
* Input domain encoded as `ISO-8859-1': www.xn--rksmrgsa-0zap8p.example
* Read string (length 33): 77 77 77 2e 78 6e 2d 2d 72 6b 73 6d 72 67 73 61 2d 30 7a 61 70 38 70 2e 65 78 61 6d 70 6c 65
* ACE label (length 23): 'www.räksmörgåsa.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_localeace_to_locale (buf, &p);
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;
}
Simon Josefsson created the library autumn 2002 when he really should have been studying mathematics.
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.
GNU Libidn (idn) - Internationalized Domain Names command line tool
idn is a utility part of GNU Libidn. It allows encoding and
decoding of punycode data and IDNA ToASCII and ToUnicode operations to
be performed on the command line, without the need to write a program
that uses libidn.
Data is read, line by line, from the standard input, and one of the operations indicated by command parameters are performed and the output is printed to standard output. If any errors are encountered, the execution of the applications is aborted.
idn recognizes these commands:
-h --help
Print help and exit
-V --version
Print version and exit
-e --punycode-encode
Encode UTF-8 to Punycode
-d --punycode-decode
Decode Punycode to UTF-8
-a --idna-to-ascii
Convert UTF-8 to ACE according to IDNA
-u --idna-to-unicode
Convert ACE to UTF-8 according to IDNA
--allow-unassigned
Toggle IDNA AllowUnassigned flag (default=off)
--usestd3asciirules
Toggle IDNA UseSTD3ASCIIRules flag (default=off)
--debug
Print debugging information (default=off)
--quiet
Don't print the welcome greeting (default=off)
Environment Variables
The CHARSET environment variable can be used to override what
character set to be used for decoding incoming data on the standard
input, and to encode data to the standard output. If your system is
set up correctly, the application will guess which character set is
used automatically. Example usage:
$ CHARSET=ISO-8859-1 idn --punycode-encode
...
9 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.
| punycode-program | Variable |
Name of the GNU Libidn idn application. The default is
env CHARSET=UTF-8 idn. This variable can be customized.
|
| punycode-encode-parameters | Variable |
Parameters passed to punycode-program to invoke punycode
encoding mode. The default is --quiet --punycode-encode. This
variable can be customized.
|
| punycode-decode-parameters | Variable |
Parameters passed to punycode-program to invoke punycode
decoding mode. The default is --quiet --punycode-decode. This
variable can be customized.
|
| punycode-encode string | Function |
| Returns a Punycode encoding of the string, after converting the input into UTF-8. |
| punycode-decode string | Function |
| Returns a possibly multibyte string which is the decoding of the string which is a punycode encoded string. |
| idna-program | Variable |
Name of the GNU Libidn idn application. The default is
env CHARSET=UTF-8 idn. This variable can be customized.
|
| idna-to-ascii-parameters | Variable |
Parameters passed to idna-program to invoke IDNA ToASCII mode.
The default is --quiet --idna-to-ascii. This variable can be
customized.
|
| idna-to-unicode-parameters | Variable |
Parameters passed idna-program to invoke IDNA ToUnicode mode.
The default is --quiet --idna-to-unicode. This variable can be
customized.
|
| idna-to-ascii string | Function |
| 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 | Function |
| Returns a possibly multibyte string which is the output of the IDNA ToUnicode operation computed on the input string. |
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Everyone is permitted to copy and distribute verbatim copies
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If you develop a new library, and you want it to be of the greatest possible use to the public, we recommend making it free software that everyone can redistribute and change. You can do so by permitting redistribution under these terms (or, alternatively, under the terms of the ordinary General Public License).
To apply these terms, attach the following notices to the library. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found.
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 by
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
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You should have received a copy of the GNU Lesser General Public
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Also add information on how to contact you by electronic and paper mail.
You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the library, if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the library
`Frob' (a library for tweaking knobs) written by James Random Hacker.
signature of Ty Coon, 1 April 1990
Ty Coon, President of Vice
That's all there is to it!
Copyright © 2000 Free Software Foundation, Inc.
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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:
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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
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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.
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