Hi, 

I noticed that in the GTP dissector, when the GTP message is a TPDU (GTPv1), 
and the "Next Extension Header" bit (and/or the S and/or PN bit) is set, the 
offset is set to 11, which points to the "Next Extension Header Type" field. If 
this field has a value of 0, then the offset is increased by one, and we move 
on to check if the next layer is IPv4, IPv6 or PPP. 

My understanding is that if the "Next Extension Header Type" field value is 0, 
then either the S or PN bit is set to 1, so increasing the offset by 1 allows 
us to move past the "Next Extension Header Type" field to the next IP/PPP 
header, since there are no extension headers.

What happens if the "Next Extension Header Type" field value is not 0? The 
offset is still at 11, which still points to the "Next Extension Header Type" 
field. There doesn't seem to be any mechanism to deal with these extension 
headers.

Thank you.

Regards,
Rayne


      
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