Overview

tinysvcmdns

tinysvcmdns is a tiny MDNS responder implementation for publishing services.

This implementation is only concerned with publishing services, without a system-wide daemon like Bonjour or Avahi. Its other goal is to be extremely small, embeddable, and have no external dependencies.

It only answers queries related to its own hostname (the A record), the service PTRs, and the "_services.dns-sd._udp.local" name, which advertises all services on a particular host.

Services consist of a single SRV and TXT record.

Decoding of MDNS packets is only done to retrieve the questions and answer RRs. The purpose for decoding answer RRs is to make sure the service PTR is not sent out if it is already included in the answer RRs.

It also only utilizes multicast packets, so no "QU" queries are accepted.

There is no name collision detection, so this means no queries are generated before publishing the services. However compliant responders will avoid using our names, since the implementation will respond to queries that match our name.

TODO

  • better, more stable & complete API
  • name collision detection

FILES

  • mdns.c - provides data structures, parsing & encoding of MDNS packets
  • mdnsd.c - implements the server socket, communication and thread
  • testmdnsd.c - an example that creates an instance until terminated

LICENSE

tinysvcmdns is licensed under the 3-clause ("modified") BSD License.

Copyright (C) 2011 Darell Tan

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  3. The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.