Hi,
I want to chane tcp header of outgoing packets.
Is it necessary to clone the NET_BUFFER_LIST and then modify the data or is it OK to create a new MDL for the TCP header and use the original NET_BUFFER and NET_BUFFER_LIST ? I am not changing the size of the packet.
If I need to clone the NET_BUFFER_LIST , is it necessary to clear the flag NDIS_CLONE_FLAGS_USE_ORIGINAL_MDLS
?
I am thinking of using WFP but I need “link status” (media connected / disconnected) information. Is it possible to get the notifications for link status in WFP model ?
> I am thinking of using WFP but I need “link status” (media connected /
disconnected) information.
There are two possible states: Connected, Not Connected.
If you consider that when you ‘send’ and the link is disconnected, well, you
cannot really send.
In the WFP if a packet has arrived from a link, clearly the link is
connected.
In the WFP if a packet is being sent on a link, clearly TCPIP thinks the
link is connected and if the link somehow becomes disconnected before ARP
has a go of making it right (assuming it is an ARP type link) then the
packet will be discarded.
Are you sure you need Link Status to do whatever it is you are going to do
to the *TCP Header*? Sure, you might need Link Status in a LWF for other
things…
Good Luck,
Dave Cattley
This question is related to WFP.
It is not necessary the data is sent on the socket when “link” goes down.
There may be no data flow.
I do not think I can see ARP packets from callout driver at Transport level.
From: xxxxx@msn.com
To: xxxxx@lists.osr.com
Subject: RE: [ntdev] LWF and modify tcp header
Date: Fri, 4 Feb 2011 18:21:05 -0500
> I am thinking of using WFP but I need “link status” (media connected /
disconnected) information.
There are two possible states: Connected, Not Connected.
If you consider that when you ‘send’ and the link is disconnected, well, you
cannot really send.
In the WFP if a packet has arrived from a link, clearly the link is
connected.
In the WFP if a packet is being sent on a link, clearly TCPIP thinks the
link is connected and if the link somehow becomes disconnected before ARP
has a go of making it right (assuming it is an ARP type link) then the
packet will be discarded.
Are you sure you need Link Status to do whatever it is you are going to do
to the *TCP Header*? Sure, you might need Link Status in a LWF for other
things…
Good Luck,
Dave Cattley
NTDEV is sponsored by OSR
For our schedule of WDF, WDM, debugging and other seminars visit:
http://www.osr.com/seminars
To unsubscribe, visit the List Server section of OSR Online at http://www.osronline.com/page.cfm?name=ListServer