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[wifi] capture: fix invoke_tcpdump() 

When the number of packets captured was >0, set -e stopped the program
as invoke_tcpdump() returned a non-zero value. This is fixed by using
echo instead of return.

Some messages improved, too.
This commit is contained in:
Matteo Cypriani 2011-08-08 10:56:50 +02:00
parent a1f0a747a8
commit a9cfd31217
1 changed files with 13 additions and 9 deletions
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22
wifi/capture.sh
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@ -49,10 +49,10 @@ CHANNEL=1
## Functions ##
# Displays the message in argument and exits
# Displays the message in argument on the error output and exits
error()
{
echo "$1"
echo "$1" >&2
clean
exit 1
}
@ -141,17 +141,21 @@ iface_up()
|| error "Cannot turn the interface up!"
}
# Invokes tcpdump and returns the number of packets captured
# Invokes tcpdump and displays the number of packets captured
invoke_tcpdump()
{
return $(tcpdump -i $IFACE -c $NB_PKT -w "$FILE" 2>&1 \
| sed -n 's/ packets captured$//p')
NCAP=$(tcpdump -i $IFACE -c $NB_PKT -w "$FILE" 2>&1 \
| sed -nr 's/([[:digit:]]+) packets captured$/\1/p')
[ "$NCAP" = "" ] \
&& error "Error parsing the tcpdump messages! (NCAP=\"$NCAP\")"
echo $NCAP
}
# Waits for a number of seconds, then kills any tcpdump process
wait_tcpdump()
{
sleep $1
echo "$1 seconds passed, killing all tcpdump processes..."
pkill tcpdump
}
@ -228,16 +232,16 @@ while [ $CAPTURED -eq 0 -a $CHANNEL -le 14 ] ; do
echo
iface_set_channel $CHANNEL
wait_tcpdump $TIMEOUT &
invoke_tcpdump
CAPTURED=$?
CAPTURED=$(invoke_tcpdump)
[ $CAPTURED -eq 0 ] \
&& echo "No packet captured on channel $CHANNEL."
&& echo "No packet captured on channel $CHANNEL." \
|| echo "$CAPTURED packets captured on channel $CHANNEL."
CHANNEL=`expr $CHANNEL + 1`
done
echo
[ $CAPTURED -gt 0 ] \
&& echo "Capture file \"$FILE\" created with $CAPTURED packets." \
&& echo "Capture file \"$FILE\" created." \
|| error "Failed to capture any packet!"
gather_system_information