C-DNS Library

Library that converts DNS transmission to C-DNS, the compacted DNS Packet Capture format.

Dependencies

This project has the following dependencies:

• [CMake >= 3.5] (https://cmake.org/)
• [Boost] (https://www.boost.org/)
• [zlib] (https://www.zlib.net/)
• [XZ Utils] (https://tukaani.org/xz/)

Optional:

• [GoogleTest] (https://github.com/google/googletest)
• [pybind11] (https://github.com/pybind/pybind11)

Build

Basic build instructions using CMake.

mkdir build
cd build
cmake -DBUILD_PYTHON_BINDINGS=ON -DBUILD_TESTS=ON ..
make
make install

If you don't want to build the Python bindings, you can omit -DBUILD_PYTHON_BINDINGS option. If you don't want to build the test suite with the library, you can omit -DBUILD_TESTS option. You can disable building of CLI tools with -DBUILD_CLI_TOOLS=OFF option.

To generate Doxygen documentation run make doc. Doxygen documentation for current release can be found here.

Installation from packages

Packages for Debian 11, 10, 9; Ubuntu 22.04, 20.04, 18.04, 16.04; Fedora 36, 35, 34, Rawhide; EPEL 8 and Arch are available from OBS (openSUSE Build Service).

Python bindings are, for the moment, available only when building the library from sources. Linux packages for Python bindings will be available soon.

Debian/Ubuntu

sudo apt-get update
sudo apt-get install -y lsb-release curl gpg

DISTRO=$(lsb_release -i -s)
RELEASE=$(lsb_release -r -s)
if [[ $DISTRO == "Ubuntu" ]]; then DISTRO="xUbuntu"; fi
if [[ $DISTRO == "Debian" && "$RELEASE" =~ ^9\..*$ ]]; then RELEASE="9.0"; fi

echo "deb http://download.opensuse.org/repositories/home:/CZ-NIC:/dns-probe/${DISTRO}_${RELEASE}/ /" | sudo tee /etc/apt/sources.list.d/dns-probe.list
curl -fsSL https://download.opensuse.org/repositories/home:CZ-NIC:/dns-probe/${DISTRO}_${RELEASE}/Release.key | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/dns-probe.gpg > /dev/null
sudo apt-get update
sudo apt-get install libcdns1 libcdns-dev

Fedora

sudo dnf config-manager --add-repo https://download.opensuse.org/repositories/home:/CZ-NIC:/dns-probe/Fedora_$(cut -d: -f5 /etc/system-release-cpe | cut -d. -f1)/home:CZ-NIC:dns-probe.repo
sudo dnf install libcdns libcdns-devel

Fedora Rawhide

sudo dnf config-manager --add-repo https://download.opensuse.org/repositories/home:/CZ-NIC:/dns-probe/Fedora_Rawhide/home:CZ-NIC:dns-probe.repo
sudo dnf install libcdns libcdns-devel

EPEL 8

cd /etc/yum.repos.d/
sudo wget https://download.opensuse.org/repositories/home:/CZ-NIC:/dns-probe/Fedora_EPEL_8_CentOS/home:CZ-NIC:dns-probe.repo
sudo yum install libcdns libcdns-devel

Arch

echo "[home_CZ-NIC_dns-probe_Arch]" | sudo tee -a /etc/pacman.conf
echo "Server = https://download.opensuse.org/repositories/home:/CZ-NIC:/dns-probe/Arch/$(uname -m)" | sudo tee -a /etc/pacman.conf

key=$(curl -fsSL https://download.opensuse.org/repositories/home:/CZ-NIC:/dns-probe/Arch/$(uname -m)/home_CZ-NIC_dns-probe_Arch.key)
fingerprint=$(gpg --quiet --with-colons --import-options show-only --import --fingerprint <<< "${key}" | awk -F: '$1 == "fpr" { print $10 }')

sudo pacman-key --init
sudo pacman-key --add - <<< "${key}"
sudo pacman-key --lsign-key "${fingerprint}"

sudo pacman -Sy home_CZ-NIC_dns-probe_Arch/c-dns

Basic Usage

To use the C-DNS library you only have to include the <cdns/cdns.h> header file.

#include <cdns/cdns.h>
...
// Create C-DNS file
CDNS::FilePreamble fp;
CDNS::CdnsExporter* exporter = new CDNS::CdnsExporter(fp, "output.out", CDNS::CborOutputCompression::NO_COMPRESSION);
CDNS::GenericQueryResponse qr;

qr.client_port = 1234;
exporter->buffer_qr(qr);
exporter->write_block();
delete exporter;

// Read C-DNS file
std::ifstream ifs("output.out", std::ifstream::binary);
CDNS::CdnsReader reader = new CDNS::CdnsReader(ifs);

bool end = false;
while (true) {
    CDNS::CdnsBlockRead block = reader->read_block(end);
    if (end)
        break;

    while (true) {
        CDNS::GenericQueryResponse gqr = block.read_generic_qr(end);
        if (end)
            break;
        ...
    }
}
delete reader;

CLI tools

The C-DNS library comes with a set of CLI tools for easy inspection and merging of C-DNS files.

cdns-blocks - Prints summary information about individual Blocks in C-DNS file.

cdns-itemcount - Prints the counts of Query/Response, Address Event Count and Malformed Message items in a C-DNS file.

cdns-items - Prints full contents of individual Query/Response, Address Event Count and Malformed Message items in a C-DNS file.

cdns-merge - Merges multiple C-DNS files into one. Can only merge files with compatible major.minor.private version.

cdns-preamble - Prints human readable contents of C-DNS file preamble.