quicdoq

Quicdoq is a simple implementation of DNS over Quic, as specified in RFC 9250. It is written in C, based on Picoquic. Like Picoquic itself, it has a dependency on the Picotls implementation of TLS 1.3, and on the Crytographic Libraries of OpenSSL.

Quicdoq components

The Quicdoq distribution has three main components:

1. A library that implements the DNS over QUIC specification. The library defines a call back API that can be used to implement DoQ client or a DoQ server.

2. A simple UDP backend that exercises the callback API and provides an interface between Quicdoq and an UDP based DNS service.

3. A command line application that can be used either as simple client or to instantiate the UDP backed server.

Partners can use the library to enable DNS over QUIC in existing DNS clients or DNS servers.

The sample application can be used to quickly prototype DNS over Quic with an existing server, using a local UDP connection to submit queries from Quicdoq to the local server.

The sample client implementation is not meant for production use. It is mainly a demonstration tool. It can be used to quickly enter a few queries, and see the responses coming back from the selected server.

Building Quicdoq

Quicdoq is developed in C, and can be built under Windows or Linux. Building the project requires first managing the dependencies, Picoquic and Picotls and OpenSSL.

Alternatively, the directory docker contains a Dockerfile to build a container for quicdoq - See Docker README for instructions.

Quicdoq on Windows

To build Picoquic on Windows, you need to:

• Install and build Openssl on your machine

• Document the location of the Openssl install in the environment variable OPENSSLDIR (OPENSSL64DIR for the x64 builds)

• Clone and compile Picotls, using the Picotls for Windows options

• Clone and compile Picoquic, using the Visual Studio 2017 solution picoquic.sln.

• Clone and compile Quicdoq, using the Visual Studio 2017 solution quicdoq.sln.

• You can use the unit tests included in the Visual Studio solution to verify the port.

Quicdoq on Linux

To build Quicdoq on Linux, you need to:

• Install libssl-dev or build Openssl on your machine

• Clone and compile Picotls, using cmake as explained in the Picotls documentation.

• Clone and compile Picotls, using cmake as explained in the Picoquic documentation.

• Clone and compile Quicdoq:

   cmake .
   make

• Run the test program quidoq_t to verify the port.

Quicdoq on MacOSX

Same build steps as Linux.

Picoquic on FreeBSD

Same build steps as Linux.

Running the demo application

This distribution includes a demo application, which is meant to illustrate the usage of the API.

    +------------+      +-------------------+
    | Client CLI |      | Relay server      |
    +------------+      +---------+---------+      +-----------+
    | Quicdoq    |      | Quicdoq | Stub    |      | Recursive |
    +------------+      +---------+ DNS     |      | DNS 
    | Quic       |      | Quic    | resolver|      | Resolver  |
    +------------+      +---------+---------+      +-----------+     
    | UDP        |<---->| UDP     | UDP     |<---->| UDP       |
    +------------+      +---------+---------+      +-----------+ 

The demo client has a simple command line interface:

quicdoq_app <options> [server_name [port [scenario]]]

The scenario consists of a set of dns queries, e.g.:

www.example:A www.example.example:AAAA example.net:NS

The client will set up a DNS over QUIC connection to the specified server, send the queries, wait for responses and display these responses.

The server receives the DNS queries from the DNS over QUIC stack, and passes them to a "relay server" which simply forwards them to a designated recursive resolver. The responses will be relayed back to the client using DNS over QUIC.

The server also has a simple command line interface:

quicdoq_app <options> -p port -d dns-server

The DNS server is designated by its IP address, such as 8.8.8.8. The options for client and server can be displayed with the command

quicdoq_app -h