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10.6 Out-of-Band Data

Out-of-band data is data transmitted with a higher priority than ordinary data. This is usually used by either side of the connection to signal exceptional conditions. Due to the fact that most TCP/IP implementations are broken in this respect, only single characters can reliably be sent this way.

Function: extensions:add-oob-handler fd char handler

Sets the function passed in handler as a handler for the character char on the connection whose descriptor is fd. In case this character arrives, the function in handler is called without any argument.

Function: extensions:remove-oob-handler fd char

Removes the handler for the character char from the connection with the file descriptor fd

Function: extensions:remove-all-oob-handlers fd

After calling this function, the connection whose descriptor is fd will ignore any out-of-band character it receives.

Function: extensions:send-character-out-of-band fd char

Sends the character char through the connection fd out of band.