Libidn2 is a free software implementation of IDNA2008, Punycode and TR46. Its purpose is to encode and decode internationalized domain names.
The library contains functionality to convert internationalized domain names to and from ASCII Compatible Encoding (ACE), following the IDNA2008 and TR46 standards.
The API consists of two main functions, idn2_to_ascii_8z for
converting data from UTF-8 to ASCII Compatible Encoding (ACE), and
idn2_to_unicode_8z8z to convert ACE names into UTF-8
format. There are several variations of these main functions, which
accept UTF-32, or input in the local system encoding. All functions
assume zero-terminated strings.
This library is backwards (API) compatible with the libidn
library. Replacing the
idna.h header with idn2.h into a program is sufficient to
switch the application from IDNA2003 to IDNA2008 as supported by this
library.
Libidn2 is believed to be a complete IDNA2008 and TR46 implementation, it contains an extensive test-suite, and is included in the continuous fuzzing project OSS-Fuzz.
You can check the current test code coverage here and the current fuzzing code coverage here.
The installed C library libidn2 is dual-licensed under LGPLv3+|GPLv2+, while the rest of the package is GPLv3+. See the file COPYING for detailed information.
Software releases of libidn2 can be downloaded from https://ftp.gnu.org/gnu/libidn/ and ftp://ftp.gnu.org/gnu/libidn/
Development of libidn2 is organized through GitLab website, and there is an issue tracker for reporting bugs.
To build Libidn2 you will need a POSIX shell to run ./configure and the Unix make tool.
The shared libidn2 library uses GNU libunistring for Unicode processing and GNU libiconv for character set conversion. You should install them before building and installing libidn2. See the following links for more information on these packages:
Note that the iconv dependency is optional -- it is required for the functions involving locale to UTF conversions -- but is recommended.
If you wish to build the project from version controlled sources, rebuild all generated files (e.g., run autoreconf), or modify some source code files, you will need to have additional tools installed. None of the following tools are necessary if you build Libidn2 in the usual way (i.e., ./configure && make).
- Automake
- Autoconf
- Libtool
- Gettext
- Texinfo
- Gperf
- Gengetopt
- Tar
- Gzip
- Texlive & epsf (for PDF manual)
- GTK-DOC (for API manual)
- Git
- Perl
- Valgrind (optional) (No HTTPS at all)
- abi-compliance-checker
- ronn
The software is typically distributed with your operating system, and the instructions for installing them differ. Here are some hints.
gNewSense/Debian/Ubuntu:
apt-get install git autoconf automake libtool texinfo gperf git2cl
apt-get install libunistring-dev gtk-doc-tools valgrind gengetopt
apt-get install abi-compliance-checker ruby-ronn
See the contributing document.
Dependencies:
- lcov (for code coverage)
To test the code coverage of the test suite use the following:
$ ./configure --enable-code-coverage
$ make && make check && make code-coverage-capture
The current coverage report can be found here.
Libidn2 is being continuously fuzzed by OSS-Fuzz.
Of course you can do local fuzzing on your own, see fuzz/README.md for instructions.
The code coverage of our fuzzers can be found here.
It is possible to cross-compile libidn2. It is expected your cross
compiler toolchain to have a specific prefix to the target host. For
example compiling for Windows with mingw64 (with prefix
i686-w64-mingw32) can be done the following way:
./configure --host=i686-w64-mingw32 && make
After ./bootstraping you find the INSTALL file in the main project
directory including generic instructions about cross-compilation.