Re: disabling checksums flag

[Guy Harris <gharris () sonic net>]

On Fri, Jul 18, 2003 at 12:55:50PM -0500, alex medvedev wrote:
> i would like to add a disable checksum flag to tcpdump.
>
> i assume this will affect ip, tcp, udp, icmp, icmp6, isoclns, igmp, vrrp,
> mobile printers, and tcpdump.c file (is it all?)
>
> proposed change:
> add a global int cksumflag=1 in tcpdump.c :)
> add a command line flag: k (?),
> which when specified disables the checksum calculation (cksumflag=0);
> check cksumflag before calculating checksums in printers.

Is there any interest in having "-k" be able to disable specific
checksums, rather than all of them?  (I don't know whether that'd be
worthwhile or not.)

> diff -urN tcpdump.orig/print-icmp.c tcpdump/print-icmp.c
> --- tcpdump.orig/print-icmp.c Fri Jul 18 12:39:24 2003
> +++ tcpdump/print-icmp.c      Fri Jul 18 12:39:34 2003
> @@ -41,6 +41,8 @@
>  #include "udp.h"
>  #include "ipproto.h"
>  
> +extern int cksumflag;
> +

You might want to put the declaration of "cksumflag" in "interface.h".
-
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