Re: [lwip-users] PPP

[Sylvain Rochet]

Hi Nick,

On Sat, Jun 23, 2012 at 07:40:58PM +0300, N.Karakotas wrote:
> 
> sent [proto=0x237d] c0 21 7d 21 7d 21 7d 20 7d 34 7d 22 7d 26 7d 20
> 7d 20 7d 20 7d 20 7d 25 7d 26 7d 5e dc fb 9a 7d ...

The issue is there, 0xc021, the protocol ID for PPP LCP seem to suffer 
from 2 a byte offset.

However, the packet seem corrupted, if 0xc021 is the LCP header, then 
the 2 previous bytes should be the PPP header, which are always 0xff 
0x03 (more or less from the HDLC protocol).

Next bytes are for sure "HDLC" framing control flag sequence... 7d 21 7d 
21 7d 20 7d 34 7d 22 7d 26 7d 20 7d 20 7d 20 7d 20 7d 25 7d 26 7d 5e dc 
fb 9a 7d.

I guess you are overlaping a buffer somewhere that goes to corrupt the 
lwIP memory.

By the way, the sio_read() + USART IRQ should be implemented in a 
great-circular buffer or a loosely double-buffering with lock support.

Sylvain

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