divert sock api q

Christian Kuhtz christian at kuhtz.com
Tue Jun 7 15:27:41 GMT 2005


Hello,

I'm using the DIVERT socket API for a proof of concept lab setup here, 
and I could use some help..

Two boxes are involved, packets traverse both in series.  The first one, 
lets call her A, is taking the UDP packet off the wire, inserts a few 
bytes after the UDP header, and sticks it back on the wire.  The second 
machine, lets call her B, grabs the packet as it comes in, strips the 
bytes we inserted, and sticks it back on the wire.

Or so goes the theory.

What I'm running into is the following.. When I sendto() the modified 
frame on A, the size is correctly reported as what the frame was 
modified to be.  When the frame arrives on B, I only recvfrom() as many 
bytes as the virgin packet used to be when it entered A prior to the 
modification.

Anyone have any idea what's going on here and how to fix this length 
mismatch?  I thought the API updates the length when the frame is sent, 
and sendto() does report the correct length..

I apologize for being so exceptionally dense, this is driving me 
completely up the walls..

Regards,
Christian



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