- static u_int16_t port;
- __be16 *portptr;
- unsigned int range_size, min, i;
-
- if (maniptype == IP_NAT_MANIP_SRC)
- portptr = &tuple->src.u.tcp.port;
- else
- portptr = &tuple->dst.u.tcp.port;
-
- /* If no range specified... */
- if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) {
- /* If it's dst rewrite, can't change port */
- if (maniptype == IP_NAT_MANIP_DST)
- return 0;
-
- /* Map privileged onto privileged. */
- if (ntohs(*portptr) < 1024) {
- /* Loose convention: >> 512 is credential passing */
- if (ntohs(*portptr)<512) {
- min = 1;
- range_size = 511 - min + 1;
- } else {
- min = 600;
- range_size = 1023 - min + 1;
- }
- } else {
- min = 1024;
- range_size = 65535 - 1024 + 1;
- }
- } else {
- min = ntohs(range->min.tcp.port);
- range_size = ntohs(range->max.tcp.port) - min + 1;
- }
-
- if (range->flags & IP_NAT_RANGE_PROTO_RANDOM)
- port = net_random();
-
- for (i = 0; i < range_size; i++, port++) {
- *portptr = htons(min + port % range_size);
- if (!nf_nat_used_tuple(tuple, ct))
- return 1;
- }
- return 0;