ipnext

FREESWAN VPN源代码包

# ipnext: increment a dotted quad IP address

set -u

for i
do

	INC=/bin/true

	n="$i"

	while $INC
	do

	    # check that we have a dotted quad

	    if expr match "X$n" 'X[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*$' >/dev/null
	    then
		    :
	    else
		    echo "\"$n\" isn't a dotted quad" >&2
		    exit 1
	    fi

	    # break out fields of dotted quad
	    q1=`expr match "X$n" 'X\([0-9][0-9]*\)\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*$'`
	    q2=`expr match "X$n" 'X[0-9][0-9]*\.\([0-9][0-9]*\)\.[0-9][0-9]*\.[0-9][0-9]*$'`
	    q3=`expr match "X$n" 'X[0-9][0-9]*\.[0-9][0-9]*\.\([0-9][0-9]*\)\.[0-9][0-9]*$'`
	    q4=`expr match "X$n" 'X[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.\([0-9][0-9]*\)$'`

	    # increment by 7.123.59.229 (arbitrary)
	    q1=`expr $q1 + 7`
	    q2=`expr $q2 + 123`
	    q3=`expr $q3 + 59`
	    q4=`expr $q4 + 229`

	    # perform carry
	    q1=`expr '(' $q1 + $q2 / 256 ')' % 256`
	    q2=`expr '(' $q2 + $q3 / 256 ')' % 256`
	    q3=`expr '(' $q3 + $q4 / 256 ')' % 256`
	    q4=`expr $q4 % 256`

	    # around again if unroutable address
	    n="$q1.$q2.$q3.$q4"
	    case "$n" in
	    10.*|192.168.*|172.16.[0-9].*|172.16.1[0-5].*|127.*)
		;;
	    *)	INC=/bin/false
	    esac
	done

	echo "$n"
done