1 files changed, 59 insertions, 0 deletions
diff --git a/watchlink/netlink_utils.cc b/watchlink/netlink_utils.cc
new file mode 100644
index 00000000..18a4b3ff
--- /dev/null
+++ b/watchlink/netlink_utils.cc
@@ -0,0 +1,59 @@
+#include <errno.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <linux/types.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <linux/rtnetlink.h>
+#include <syslog.h>
+
+#include "netlink_utils.hh"
+
+
+/* Maskbit. */
+static u_char maskbit[] = {0x00, 0x80, 0xc0, 0xe0, 0xf0,
+			         0xf8, 0xfc, 0xfe, 0xff};
+
+/* Convert masklen into IP address's netmask. */
+void
+masklen2ip (int masklen, struct in_addr *netmask)
+{
+  u_char *pnt;
+  int bit;
+  int offset;
+
+  memset (netmask, 0, sizeof (struct in_addr));
+  pnt = (unsigned char *) netmask;
+
+  offset = masklen / 8;
+  bit = masklen % 8;
+  
+  while (offset--)
+    *pnt++ = 0xff;
+
+  if (bit)
+    *pnt = maskbit[bit];
+}
+
+
+in_addr_t
+ipv4_broadcast_addr (in_addr_t hostaddr, int masklen)
+{
+  struct in_addr mask;
+
+  masklen2ip (masklen, &mask);
+  return (masklen != 32-1) ?
+    /* normal case */
+    (hostaddr | ~mask.s_addr) :
+    /* special case for /31 */
+    (hostaddr ^ ~mask.s_addr);
+}
+
+in_addr_t
+ipv4_first_addr (in_addr_t hostaddr, int masklen)
+{
+  struct in_addr mask;
+  masklen2ip (masklen, &mask);
+  return (hostaddr & mask.s_addr);
+}
+