/**
* Test to check whether the IPs given overlap or not at all
*
* @param flowIntersect - the current potential intersection
* @param maskShift - the shift value (ie. either for a src_ip or a dst_ip).
* @param masklenX - the netmask for the first ip.
* @param masklenY - the netmask for the second ip.
* @param x - the first ip
* @param y - the second ip.
* @return the smallest intersection of this ip space.
*/
private int testIP(
FlowIntersect flowIntersect, int maskShift, int masklenX, int masklenY, int x, int y) {
int min = Math.min(masklenX, masklenY); // get the less specific address
int max = Math.max(masklenX, masklenY); // get the more specific address
int min_encoded = 32 - min; // because OpenFlow does it backwards... grr
int max_encoded = 32 - max; // because OpenFlow does it backwards... grr
if (max_encoded >= 32) // set all the bits if this is in fact fully
max_encoded = 63; // wildcarded; if only for wireshark's sake
int mask;
if (min == 0) mask = 0; // nasty work around for stupid signed ints
else mask = ~((1 << min_encoded) - 1); // min < 32, so no signed issues
// int mask = (1 << min) - 1;
if ((x & mask) != (y & mask)) // if these are not in the same CIDR block
flowIntersect.setMatchType(MatchType.NONE);
// else there is some overlap
OFMatch interMatch = flowIntersect.getMatch();
int wildCards = interMatch.getWildcards();
// turn off all bits for this match and then turn on the used ones
// use MAX not MIN, because we want the most specific intersection
// split into two ops, so we can see intermediate step in debugger
// assumes SRC mask == DST mask
// turn off all bits for this match (making it an exact match)
wildCards = wildCards & ~(((1 << OFMatch.OFPFW_NW_SRC_BITS) - 1) << maskShift);
// turn on the bits for the intersection
wildCards = wildCards | max_encoded << maskShift;
interMatch.setWildcards(wildCards);
if (masklenX < masklenY) {
flowIntersect.maybeSubset = false;
return y;
} else if (masklenX > masklenY) {
flowIntersect.maybeSuperset = false;
return x;
}
// note that b/c of how CIDR addressing works, there is no overlap that
// is not a SUB or SUPERSET
return x; // x == y; doesn't matter
}
