[PATCH] Maintain outgoing TCP meta buffer

[Scott Lamb]

On Jan 14, 2006, at 7:33 AM, Guus Sliepen wrote:
> Adding a buffer and testing for writablity will certainly prevent the
> problems that make BlockingTCP necessary. But, how large do we  
> allow the
> buffers to grow? What do we do when it reaches a limit?

You're right: a limit definitely needs to be set. I've got enough  
memory to throw at things, but I just tried simulating the worst  
case: I took my Ethernet interface down and ran "ping -fs 65507  
172.16.0.2". I thought it would realize the connection went down  
before growing to be unreasonably large, but apparently not. In the  
two and a half minutes before it pulled the plug, the buffer grew to  
284 megs.

I'm tempted to address this by time rather than buffer size. Maybe if  
it's had unflushed data for five seconds (which would be  
configurable), it will terminate the connection as your code did  
before. This would limit the buffer growth, and it'd make tinc notice  
problems even if you stop filling the buffer.

Regards,
Scott