ipfw modip [DF|TOS|DSCP|TTL]

[Vadim Goncharov]

04.03.08 @ 09:23 Marcelo Araujo wrote:

> Hi all,
> I started a work to create a new function called of modip, but I've some
> doubts around this implementation.
> I created inside of ipfw2.c a case statement called of TOK_SETMODIP, I
> check if user passed one of the options(DF,TOS,DSCP,TTL), after set an
> int with the respective value.
> Now, I need  to call O_SETMODIP within ip_fw2.c going with parameter
> opmodip, and inside O_SETMODIP I can do a goto to O_SETIPTOSPRE as  
> example.

Only as example - no O_SETIPTOSPRE should be in actual patch...

> ipfw2.c:
> 4913     /* New Implementation MODIP. */
> 4914     /* [DF|TOS|DSCP|TTL]         */
> 4915     case TOK_SETMODIP: {
> 4916         int opmodip = 0;
> 4917         NEED1("need modip [DF|TOS|DSCP|TTL] arg\n");

You're checking only one argument, but there are two - e.g. "tos" and  
actual arg.

> 4918         if (_substrcmp(*av, "DF") == 0 ||
> 4919               _substrcmp(*av, "df") == 0) {
> 4920             opmodip = 1;

Operation constants for O_MODIP should be #defines in ip_fw.h rather than  
plain 1, 2, 3, etc.

> 4938         fill_cmd(cmd, O_SETMODIP, 0, modip);

Why "modip" var, not "opmodip" you've used before?

> 4939         ac--; av++;
> 4940         printf("Value %d\n", opmodip);
> 4941         break;
> 4942     }

> When I execute the ipfw with the option I've this output:
> island# ipfw add modip
> ipfw: need modip [DF|TOS|DSCP|TTL] arg
>
> and
>
> island# ipfw add modip tos
> TOS....
> ipfw: invalid flag tos
>
> I'd like to pass as follows:
> island# ipfw add modip tos flashover ip from any to any
>
> My problem I believe are in fill_cmd().
> Somebody can help me with this problem?

I think problem is in "ac--; av++" count times, not in fill_cmd() which is  
only instruction setter, not parser.

-- 
WBR, Vadim Goncharov