Add websocket webfs patch and notes

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+# Creating websocket connections via 9front's webfs
+
+With the following patch (note: work in progress, contains bugs), 9front's webfs can be used
+to create websocket connections. The patch is available [here](/_files/websocket-webfs.patch).
+
+## The idea
+
+Creating a websocket connection is done just like creating a http request is, except the
+url must use scheme `wss://` or `ws://`, and the `body` file must be opened read-write to
+allow both sending and receiving.
+
+The very first message to be read from `body` is always "websocket ready", meaning the connection has been
+established. After that the actual communication begins.
+
+Webfs itself takes care of the control messages, so only the data messages gets delivered to the user, in a textual
+format that is easy to parse. Each message read and writen to `body` consists of a 22 byte header in the following format
+
+	b nnnnnnnnnnnnnnnnnnnn
+
+or
+
+	t nnnnnnnnnnnnnnnnnnnn
+
+for binary and text messages respectively. The 20 last bytes are a 0-padded ascii number in base 10, telling the size of the message body,
+which follows directly after the header.
+
+## Example program
+
+To demonstrate, the following rc script connects to `wss://echo.websocket.org` which is a service that echos everything
+back to the user.
+
+	#!/bin/rc
+	
+	rfork en
+	
+	webfs
+	
+	fn sendtextmsg{
+		awk 'BEGIN{printf "t %0.20d%s", length(ARGV[1]), ARGV[1]}' $1 >[1=0]
+	}
+	
+	fn readheader{
+		header=`{read -c 22}
+		length=`{echo $header(2) p | dc}
+		echo $header(1) $length
+	}
+	
+	fn handlemsg{
+		echo Handling message:
+		echo '	TYPE  :' $1
+		echo '	LENGTH:' $2
+		echo '	BODY  :' $3
+	}
+	
+	<>/mnt/web/clone {
+		d=/mnt/web/^`{sed 1q}
+	
+		echo url wss://echo.websocket.org >[1=0]
+	
+		<>$d/body {
+			read -n 1 # Read the ready message
+	
+			sendtextmsg 'First message sent'
+			while(header=`{readheader}){
+				echo Header: $header
+				body=`''{read -c $header(2)}
+				handlemsg $header(1) $header(2) $body
+				sleep 2
+				sendtextmsg 'Echo test'
+			}
+		}
+	}
+
+## Bugs
+
+Yes. The code doesn't really handle errors or connection shutdowns yet. Also, I need to add proper cleanup code
+around in different places.
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