[PATCH] Re: changing the ToS in IP Header

[Terry Lambert]

Ashish Kulkarni wrote:
> as I mentioned earlier, I want to do it for all outgoing packets on an
> interface, not on per socket basis. I actually was hoping that somene
> would provide me pointers to where I should look in the source (me being a
> newcomer to BSD as such) to implement a sysctl that will allow me to
> change the tos, eg. "net.inet.ip.tos". I'd have prefered to use a packet
> mangling firewall, but afaik there are none which do that so I'll have to
> do it the hard way ;-)

The attached patch adds a new sysctl oid for support of a
"net.inet.ip.default_tos" (default: 0).

I sent it as a context diff, in case the kernel has changed
more than a little since the last time I updated.

Note: I only compile-tested this.

-- Terry
-------------- next part --------------
Index: in_pcb.c
===================================================================
RCS file: /cvs/src/sys/netinet/in_pcb.c,v
retrieving revision 1.120
diff -c -r1.120 in_pcb.c
*** in_pcb.c	21 Feb 2003 05:28:27 -0000	1.120
--- in_pcb.c	26 May 2003 20:56:30 -0000
***************
*** 31,37 ****
   * SUCH DAMAGE.
   *
   *	@(#)in_pcb.c	8.4 (Berkeley) 5/24/95
!  * $FreeBSD: src/sys/netinet/in_pcb.c,v 1.120 2003/02/21 05:28:27 cjc Exp $
   */
  
  #include "opt_ipsec.h"
--- 31,37 ----
   * SUCH DAMAGE.
   *
   *	@(#)in_pcb.c	8.4 (Berkeley) 5/24/95
!  * $FreeBSD$
   */
  
  #include "opt_ipsec.h"
***************
*** 104,109 ****
--- 104,114 ----
  int	ipport_reservedhigh = IPPORT_RESERVED - 1;	/* 1023 */
  int	ipport_reservedlow = 0;
  
+ /*
+  * Default type of service for all IP packets.
+  */
+ int	ip_default_tos = 0;
+ 
  #define RANGECHK(var, min, max) \
  	if ((var) < (min)) { (var) = (min); } \
  	else if ((var) > (max)) { (var) = (max); }
***************
*** 124,129 ****
--- 129,145 ----
  	return error;
  }
  
+ static int
+ sysctl_net_iptos_check(SYSCTL_HANDLER_ARGS)
+ {
+ 	int error = sysctl_handle_int(oidp,
+ 		oidp->oid_arg1, oidp->oid_arg2, req);
+ 	if (!error) {
+ 		RANGECHK(ip_default_tos, 0, 255);
+ 	}
+ 	return error;
+ }
+ 
  #undef RANGECHK
  
  SYSCTL_NODE(_net_inet_ip, IPPROTO_IP, portrange, CTLFLAG_RW, 0, "IP Ports");
***************
*** 144,149 ****
--- 160,167 ----
  	   CTLFLAG_RW|CTLFLAG_SECURE, &ipport_reservedhigh, 0, "");
  SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, reservedlow,
  	   CTLFLAG_RW|CTLFLAG_SECURE, &ipport_reservedlow, 0, "");
+ SYSCTL_PROC(_net_inet_ip, OID_AUTO, default_tos, CTLTYPE_INT|CTLFLAG_RW,
+ 	   &ip_default_tos, 0, &sysctl_net_iptos_check, "I", "");
  
  /*
   * in_pcb.c: manage the Protocol Control Blocks.
***************
*** 174,179 ****
--- 192,198 ----
  	inp->inp_gencnt = ++pcbinfo->ipi_gencnt;
  	inp->inp_pcbinfo = pcbinfo;
  	inp->inp_socket = so;
+ 	inp->inp_ip_tos = (u_char)ip_default_tos;
  #ifdef IPSEC
  	error = ipsec_init_policy(so, &inp->inp_sp);
  	if (error != 0) {