vlevigneron / zonemaster-ldns

A Perl interface module for Zonemaster to NLnet Labs' ldns library

Zonemaster LDNS

Table of contents

• Introduction
• Dependencies and Compatibility
• Installation and verification
  • Recommended installation
  • Installation from source
  • Post-installation sanity check
  • Testing
• Optional features
  • Ed25519
  • IDN
  • Internal ldns
  • Randomized capitalization

Introduction

This module provides a Perl interface to the ldns library from NLnet Labs. This module includes the necessary C code from ldns, so the library does not need to be globally installed. It does, however, rely on a sufficiently recent version of OpenSSL being present.

This module is written as part of the Zonemaster project, and therefore primarily exposes the functionality needed for that. Since Zonemaster is a diagnostic tool, that means the functions most used are those for looking things up and inspecting them.

If you want a module that specifically aims to be a complete and transparent interface to ldns, DNS::LDNS is a better fit than this module.

Initially this module was named Net::LDNS.

Dependencies and compatibility

Run-time dependencies:

• openssl (openssl >= 1.1.1 unless Ed25519 is disabled)
• libidn (if IDN is enabled)
• libldns (if Internal ldns is disabled; libldns >= 1.7.0, or libldns >= 1.7.1 if Ed25519 is enabled)

Compile-time dependencies (only when installing from source):

• make
• Devel::CheckLib
• Module::Install
• Module::Install::XSUtil
• Test::More >= 1.302015
• git (if Internal ldns is enabled)
• libtool (if Internal ldns is enabled)
• autoconf (if Internal ldns is enabled)
• automake (if Internal ldns is enabled)

Test-time dependencies:

• Test::Fatal

There is a small part in the code that may not be compatible with non-Unix operating systems, in that it assumes that the file /dev/null exists.

Installation and verification

Recommended installation

The recommended way to install Zonemaster::LDNS is to install it from CPAN as a dependency to Zonemaster::Engine. If you follow the installation instructions for Zonemaster::Engine you will get all the prerequisites and dependencies for Zonemaster::LDNS before installing it from CPAN.

Installation from source

Override the default set of features by appending --FEATURE and/or --no-FEATURE options to the perl Makefile.PL command.

git clone https://github.com/zonemaster/zonemaster-ldns
cd zonemaster-ldns
perl Makefile.PL
make
make test
make install

Note: The source ZIP files downloaded from Github are broken with respect to this instruction.

Post-installation sanity check

perl -MZonemaster::LDNS -E 'say Zonemaster::LDNS->new("8.8.8.8")->query("zonemaster.net")->string'

The above command should print some dig-like output.

Testing

Some of the unit tests depend on data on Internet, which may change. To avoid false fails, those unit tests are only run if the environment variable TEST_WITH_NETWORK is true. By default that variable is unset (those tests are not run). To run all tests, execute

TEST_WITH_NETWORK=1 make test

Optional features

When installing from source, you can choose to enable or disable a number of optional features using command line options to the perl Makefile.PL commands.

Ed25519

Enabled by default. Disabled with --no-ed25519

Requires support for Ed25519 in both openssl and ldns.

Note: Zonemaster Engine relies on this feature for its analysis when Ed25519 (algorithm 15) is being used in DNS records.

IDN

Enabled by default. Disable with --no-idn.

If the IDN feature is enabled, the GNU libidn library will be used to add a simple function that converts strings from Perl's internal encoding to IDNA domain name format. In order to convert strings from whatever encoding you have to Perl's internal format, use L. If you need any kind of control or options, use LNet::LibIDN. The included function here is only meant to assist in the most basic case, although that should cover a lot of real-world use cases.

Note: The Zonemaster Engine test suite assumes this feature is enabled.

Internal ldns

Enabled by default. Disable with --no-internal-ldns.

When enabled, an included version of ldns is statically linked into Zonemaster::LDNS. When disabled, libldns is dynamically linked just like other dependencies.

Randomized capitalization

Disabled by default. Enable with --randomize.

Note: This feature is experimental.

Randomizes the capitalization of returned domain names.

Custom OpenSSL

Disabled by default. Enabled with --prefix-openssl=/path/to/openssl.

Enabling this makes the build tools look for OpenSSL in a non-standard place.

Technically this does two things:

• Libcrypto is sought in the lib directory under the given directory.
• The include directory under the given directory is added to the include path.

Note: The lib directory under the given path must be known to the dynamic linker or feature checks will fail.