Websocket Server for Arduino 1.0

This is a simple library that implements a Websocket server running on an Arduino 1.0 or higher. The Websocket specification is still kind of a moving target. This implementation is based on the proposed standard published December 2011. This version has support by the current version (June 2012) of Firefox, Chrome, and Safari 6.0 beta (not older Safari, unfortunately) and thus is quite usable.

The implementation in this library has restrictions as the Arduino platform resources are very limited:

• The server only handles TXT frames.
• The server only handles single byte chars. The Arduino just can't handle UTF-8 to it's full.
• The server only accepts final frames with maximum payload length of 64 bytes. No fragmented data, in other words.
• The server silently ignores all frames except TXT and CLOSE. This will most likely not be a problem for an Arduino based app.

_ Required headers (example):_

GET /whatever HTTP/1.1
Host: server.example.com
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
Origin: http://example.com
Sec-WebSocket-Version: 13

The server checks that all of these headers are present, but only cares that the version is 13.

Response example:

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=

The last line is the Base64 encoded SHA-1 hash of the key with a concatenated GUID, as specified by the standard.

Getting started

Install the library to "libraries" folder in your Arduino sketchbook folder. For example, on a mac that's ~/Documents/Arduino/libraries.

Try the supplied echo example together with the the web based test client to ensure that things work.

Start playing with your own code and enjoy!

Oh by the way, quoting myself:

Don't forget to place a big fat disclaimer in the README. There is most certainly bugs in the code and I may well have misunderstood some things in the specification which I have only skimmed through and not slept with. So please do not use this code in appliancies where people or pets could get hurt, like space shuttles, dog tread mills and Large Hadron Colliders.