return -EINVAL;
}
-unsigned in_addr_netmask_to_prefixlen(const struct in_addr *addr) {
+unsigned char in_addr_netmask_to_prefixlen(const struct in_addr *addr) {
assert(addr);
return 32 - u32ctz(be32toh(addr->s_addr));
}
+
+struct in_addr* in_addr_prefixlen_to_netmask(struct in_addr *addr, unsigned char prefixlen) {
+ assert(addr);
+ assert(prefixlen <= 32);
+
+ /* Shifting beyond 32 is not defined, handle this specially. */
+ if (prefixlen == 0)
+ addr->s_addr = 0;
+ else
+ addr->s_addr = htobe32((0xffffffff << (32 - prefixlen)) & 0xffffffff);
+
+ return addr;
+}
+
+int in_addr_default_prefixlen(const struct in_addr *addr, unsigned char *prefixlen) {
+ uint8_t msb_octet = *(uint8_t*) addr;
+
+ /* addr may not be aligned, so make sure we only access it byte-wise */
+
+ assert(addr);
+ assert(prefixlen);
+
+ if (msb_octet < 128)
+ /* class A, leading bits: 0 */
+ *prefixlen = 8;
+ else if (msb_octet < 192)
+ /* class B, leading bits 10 */
+ *prefixlen = 16;
+ else if (msb_octet < 224)
+ /* class C, leading bits 110 */
+ *prefixlen = 24;
+ else
+ /* class D or E, no default prefixlen */
+ return -ERANGE;
+
+ return 0;
+}
+
+int in_addr_default_subnet_mask(const struct in_addr *addr, struct in_addr *mask) {
+ unsigned char prefixlen;
+ int r;
+
+ assert(addr);
+ assert(mask);
+
+ r = in_addr_default_prefixlen(addr, &prefixlen);
+ if (r < 0)
+ return r;
+
+ in_addr_prefixlen_to_netmask(mask, prefixlen);
+ return 0;
+}
+
+int in_addr_mask(int family, union in_addr_union *addr, unsigned char prefixlen) {
+ assert(addr);
+
+ if (family == AF_INET) {
+ struct in_addr mask;
+
+ if (!in_addr_prefixlen_to_netmask(&mask, prefixlen))
+ return -EINVAL;
+
+ addr->in.s_addr &= mask.s_addr;
+ return 0;
+ }
+
+ if (family == AF_INET6) {
+ unsigned i;
+
+ for (i = 0; i < 16; i++) {
+ uint8_t mask;
+
+ if (prefixlen >= 8) {
+ mask = 0xFF;
+ prefixlen -= 8;
+ } else {
+ mask = 0xFF << (8 - prefixlen);
+ prefixlen = 0;
+ }
+
+ addr->in6.s6_addr[i] &= mask;
+ }
+
+ return 0;
+ }
+
+ return -EAFNOSUPPORT;
+}