FreeBSD bpf patch

[Carter Bullard]

Hey Peter,
   I'm going to reword your introductory statements,
as it appears that you are saying that in order for
argus to run properly on FreeBSD, you have to modify
the kernel.  It has nothing to do with argus, but
rather a general bug with bpf on FreeBSD.

   Is that OK?

Carter

Carter Bullard
QoSient, LLC
300 E. 56th Street, Suite 18K
New York, New York  10022

carter at qosient.com
Phone +1 212 588-9133
Fax   +1 212 588-9134

> -----Original Message-----
> From: owner-argus at lists.andrew.cmu.edu
> [mailto:owner-argus at lists.andrew.cmu.edu]On Behalf Of Peter Van Epp
> Sent: Friday, February 16, 2001 10:59 AM
> To: argus
> Subject: FreeBSD bpf patch
> 
> 
> 	As promised here is the FreeBSD bpf patch. I expect you 
> want to point
> to this from the INSTALL readme for those folks running on 
> FreeBSD. I need
> to check OpenBSD and netBSD but I expect (from communication 
> with the OpenBSD
> folks) that it is fixed in OpenBSD 2.8 (but not in 2.7).
> 
> Peter Van Epp / Operations and Technical Support 
> Simon Fraser University, Burnaby, B.C. Canada
> 
> 
> 
> 	For running argus (1.8 or 2.0) on FreeBSD at least up 
> to 4.2-RELEASE
> and until FreeBSD PR kern/22063 gets applied, you need to 
> apply the following
> patch to /sys/net/bpf.c and /sys/net/bpfdesc.h and rebuild 
> the kernel to 
> make bpf function correctly with argus. As bpf currently 
> stands partly filled
> buffers won't get forwarded to argus when a select timeout 
> occurs and argus will
> lose packets. To demonstrate the bug start argus on Freebsd 
> and send a small
> number of packets (10 or so) which won't fill the bpf buffer. 
> You will discover
> when you hup argus that ra will report no data received with 
> an unpatched
> FreeBSD kernel. When you apply the patch the packets will 
> show up correctly
> (because they get forwarded when the select system call from 
> argus times out).
> 
> *** /sys/net/bpf.c.orig	Sat Oct 14 19:00:59 2000
> --- /sys/net/bpf.c	Mon Oct 16 09:30:24 2000
> ***************
> *** 1054,1061 ****
>   	if (events & (POLLIN | POLLRDNORM)) {
>   		if (d->bd_hlen != 0 || (d->bd_immediate && 
> d->bd_slen != 0))
>   			revents |= events & (POLLIN | POLLRDNORM);
> ! 		else
> ! 			selrecord(p, &d->bd_sel);
>   	}
>   	splx(s);
>   	return (revents);
> --- 1054,1076 ----
>   	if (events & (POLLIN | POLLRDNORM)) {
>   		if (d->bd_hlen != 0 || (d->bd_immediate && 
> d->bd_slen != 0))
>   			revents |= events & (POLLIN | POLLRDNORM);
> ! 		else {
> !         		/*
> !          		 * If there is a timeout and no data in 
> the hold buffer
> !        			 * see if there has been data 
> in the capture buffer
> ! 			 * for more than a timeout interval. If 
> so rotate the
> ! 			 * buffer to push the packets to the user.
> !         		 */
> ! 			if ((d->bd_slen != 0) && (d->bd_hlen == 0)) {
> ! 				if ((d->bd_rtout != -1) && 
> ! 				    (d->bd_rdstart + 
> d->bd_rtout) > ticks) {
> ! 					ROTATE_BUFFERS(d);
> ! 					revents |= events & 
> (POLLIN | POLLRDNORM);
> ! 				}
> ! 			} else 
> ! 				selrecord(p, &d->bd_sel);
> ! 				
> ! 		}
>   	}
>   	splx(s);
>   	return (revents);
> ***************
> *** 1219,1224 ****
> --- 1234,1245 ----
>   	 */
>   	(*cpfn)(pkt, (u_char *)hp + hdrlen, (hp->bh_caplen = 
> totlen - hdrlen));
>   	d->bd_slen = curlen + totlen;
> + 
> + 	/*
> + 	 * Mark the time the last packet was seen for poll 
> timeout processing.
> + 	 */
> + 
> + 	d->bd_rdstart = ticks;
>   }
>   
>   /*
> *** /sys/net/bpfdesc.h.orig	Sat Oct 14 19:16:07 2000
> --- /sys/net/bpfdesc.h	Sat Oct 14 19:21:54 2000
> ***************
> *** 69,74 ****
> --- 69,75 ----
>   
>   	struct bpf_if *	bd_bif;		/* interface descriptor */
>   	u_long		bd_rtout;	/* Read timeout in 'ticks' */
> +         u_long          bd_rdstart;     /* when the read started */
>   	struct bpf_insn *bd_filter; 	/* filter code */
>   	u_long		bd_rcount;	/* number of packets received */
>   	u_long		bd_dcount;	/* number of packets dropped */
> 
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