From 7dd553874268845ada55ac7f17d92bbefbc3a981 Mon Sep 17 00:00:00 2001 From: keramida Date: Fri, 30 Jan 2009 19:33:04 +0000 Subject: Sometimes, depending on the bpf filter rules used in $PATTERN, the example script of the manpage feeds awk(1) with values larger than UINT32_MAX. Then awk prints a negative value, and this messes up $BPFPROG. Trying to load the resulting bpf byte codes with ngctl then fails. For example, the output for PATTERN="udp and dst net 255.255.0.0/16" should be (all in one line): bpf_prog_len=10 bpf_prog=[ { code=40 jt=0 jf=0 k=12 } { code=21 jt=7 jf=0 k=34525 } { code=21 jt=0 jf=6 k=2048 } { code=48 jt=0 jf=0 k=23 } { code=21 jt=0 jf=4 k=17 } { code=32 jt=0 jf=0 k=30 } { code=84 jt=0 jf=0 k=4294901760 } { code=21 jt=0 jf=1 k=4294901760 } { code=6 jt=0 jf=0 k=8192 } { code=6 jt=0 jf=0 k=0 } ] The two k=4294901760 values are displayed as k=-2147483648 by awk. Replace the awk script of the manpage example with a slower but safer version, that doesn't really attempt to convert the byte code printed by tcpdump from string to number and back. PR: docs/123255 Submitted by: Eugenio Maffione, eugenio.maffione at telecomitalia.it MFC after: 3 days --- share/man/man4/ng_bpf.4 | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-) diff --git a/share/man/man4/ng_bpf.4 b/share/man/man4/ng_bpf.4 index 9e6f3d5..4f89729 100644 --- a/share/man/man4/ng_bpf.4 +++ b/share/man/man4/ng_bpf.4 @@ -156,21 +156,14 @@ INHOOK="hook1" MATCHHOOK="hook2" NOTMATCHHOOK="hook3" -cat > /tmp/bpf.awk << xxENDxx -{ - if (!init) { - printf "bpf_prog_len=%d bpf_prog=[", \\$1; - init=1; - } else { - printf " { code=%d jt=%d jf=%d k=%d }", \\$1, \\$2, \\$3, \\$4; - } -} -END { - print " ]" -} -xxENDxx - -BPFPROG=`tcpdump -s 8192 -ddd ${PATTERN} | awk -f /tmp/bpf.awk` +BPFPROG=$( tcpdump -s 8192 -ddd ${PATTERN} | \\ + ( read len ; \\ + echo -n "bpf_prog_len=$len" ; \\ + echo -n "bpf_prog=[" ; \\ + while read code jt jf k ; do \\ + echo -n " { code=$code jt=$jt jf=$jf k=$k }" ; \\ + done ; \\ + echo " ]" ) ) ngctl msg ${NODEPATH} setprogram { thisHook=\\"${INHOOK}\\" \\ ifMatch=\\"${MATCHHOOK}\\" \\ -- cgit v1.1