zeroconf/README.markdown
df 964c2dd28d Document current version
Add description of HummyNew version and de-emphasise DT's health warning, now mostly obsolete.
2020-07-27 01:03:59 +00:00

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NOTICE FROM THE ORIGINAL AUTHOR
-------------------------------
This project is un-maintained, and has been since 2013.
There are known vulnerabilities that have been disclosed, and quite possibly
others that have yet to be disclosed. Refer to the issue tracker.
You are advised to NOT use this library for any new projects / products.
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.
Unicast queries are accepted but only legacy queries (non-mDNS source port) get a unicast response (think `dig`).
FILES
------
* mdns.c - provides data structures, parsing & encoding of MDNS packets
* mdns.h - interface to the above
* mdnsd.c - implements the server socket, communication and thread
* mdnsd.h - interface to the above
* testmdnsd.c - an example that creates an instance until terminated
HISTORY
-------
Darell Tan is the original author. His version, to which the Notice above refers, can be found at https://bitbucket.org/geekman/tinysvcmdns, and in a branch of this repository. Several forked versions can be found across the Internet. The version at https://github.com/philippe44/TinySVCmDNS is adapted for more platforms and addresses some of the issues in the original version. Meanwhile, the code was adopted as part of Samsung's TizenRT [IOT](https://www.briansolis.com/tag/internet-of-shit/) framework, but without maintaining the change history between that version and the original. The TizenRT version implemented most of the RFC 6762/6763 features missing from the original version, and also fixed the known vulnerabilities mentioned in the Notice.
In 2012 the original version was [adapted as a package](https://hummy.tv/forum/threads/announcing-dns-name-on-upnp-for-webif.1640/) for the [Custom Firmware](https://hummy.tv/forum/forums/hd-hdr-fox-t2-customised-firmware.28/) on the Humax HD/R-Fox T2 TV set-top boxes. This fork (let's call it HummyPkg) differed mostly in the `testmdnsd.c` program which was specialised for the package. However it did not track the changes in the original version. The branch named HummyPkg does so.
The HummyPkg version enabled other LAN devices to find the tinysvcmdns host, but only if they were able to resolve names by querying the mDNS service; this excluded other Humax CF boxes as they rely on a `hosts` file for name resolution. It also had to be restarted if the LAN IP address of the tinysvcmdns host changed, as would happen at startup using a WiFi dongle.
By reabsorbing the changes from the TizenRT version into the HummyPkg version and making some further enhancements, it has been possible to create a version named HummyNew that addresses those issues. This comprises a highly modified `testmdnsd.c` that can parse and write `hosts` files together with an almost fully featured mDNS implementation.
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.