Date: Tue, 17 Oct 2000 14:39:00 -0700 (PDT) From: vanepp@sfu.ca To: freebsd-gnats-submit@FreeBSD.org Subject: kern/22063: bpf when used with the select system call with timeout doesn't forward packets on timeout Message-ID: <20001017213900.265D137B4CF@hub.freebsd.org>
next in thread | raw e-mail | index | archive | help
>Number: 22063
>Category: kern
>Synopsis: bpf when used with the select system call with timeout doesn't forward packets on timeout
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Oct 17 14:40:00 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator: Peter Van Epp
>Release: 4.1-RELEASE
>Organization:
Simon Fraser University
>Environment:
FreeBSD demob.ucs.sfu.ca 4.1-RELEASE FreeBSD 4.1-RELEASE #19: Tue Oct 17 12:37:56 PDT 2000 vanepp@demob.ucs.sfu.ca:/usr/src/sys/compile/GENERIC i386
>Description:
When bpf is accessed via libpcap with the select system call with a timeout set if a less than full buffer of packets received on the interface (and passed to bpf.c) they will never be returned to libpcap even on a timeout. OpenBSD has a partial fix for this (it gets the first packet of 9 up and leaves the other 8) which I have corrected,
reported to OpenBSD and ported to FreeBSD.
As a side note one of the OpenBSD people is working on a better bpf implementation and would be interested in help by someone knowledgable in the FreeBSD VM system to assist porting his code when finished to FreeBSD.
>How-To-Repeat:
To reproduce:
1) Install argus-1.8.1.tar.gz and argus-1.8.1.patches from
ftp.andrew.cmu.edu/pub/argus
2) Install the test.dif patch below to report Total packets received from
libpcap to show the problem.
3) start argus_bpf as below and supply it a less than buffer full of packets
(I used tcpreplay from www.anzen.com/research/nidsbench on another machine
playing back a tcpdump file: tcpreplay -ixl0 -r1 ip.small.tcpdump).
4) Examine output as below (unpatched then patched).
Unpatched bpf.c (all 9 packets still in bpf.c buffer, none get to libpcap):
demob# bin/argus_bpf -i xl0 -P0 -w argus.log
^C
9 packets recv'd by filter
0 packets dropped by kernel
demob# bin/ra -r argus.log -n
Tue 10/17 12:34:19 man 1.168.192.0 255.255.255.0 INT
Tue 10/17 12:34:33 man pkts 9 drops 0 flows 0 CLO
bpf.c and bpfdesc.h patched as below and kernel recompiled and installed:
demob# bin/argus_bpf -ixl0 -P0 -w argus.log
Total packets: 1
Total packets: 2
Total packets: 3
Total packets: 4
Total packets: 5
Total packets: 6
Total packets: 7
Total packets: 8
Total packets: 9
^C
9 packets recv'd by filter
0 packets dropped by kernel
demob# bin/ra -r argus.log -n
Tue 10/17 09:50:50 man 1.168.192.0 255.255.255.0 INT
Tue 10/17 09:51:16 M tcp 130.71.240.184.2197 |> 142.58.12.12.80 RST
Tue 10/17 09:51:23 man pkts 9 drops 0 flows 1 CLO
demob#
Apply in argus-1.8.1/ directory.
*** server/cons_ether.c.orig Tue Oct 17 01:45:10 2000
--- server/cons_ether.c Tue Oct 17 01:45:59 2000
***************
*** 95,100 ****
--- 95,101 ----
if (p && caplen) {
totalPktsRcv++;
+ printf("Total packets: %d\n", totalPktsRcv);
globaltvp.tv_sec = h->ts.tv_sec;
globaltvp.tv_usec = h->ts.tv_usec;
>Fix:
begin 600 patch.dif
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:8F5R(&]F('!A8VME=',@9')O<'!E9" J+PH)
end
>Release-Note:
>Audit-Trail:
>Unformatted:
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20001017213900.265D137B4CF>