1 files changed, 25 insertions, 0 deletions
diff --git a/src/libip/classmask.c b/src/libip/classmask.c
new file mode 100644
index 00000000..5932f878
--- /dev/null
+++ b/src/libip/classmask.c
@@ -0,0 +1,25 @@
+#include <u.h>
+#include <libc.h>
+#include <ip.h>
+
+uchar classmask[4][16] = {
+	0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0xff,  0xff,0x00,0x00,0x00,
+	0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0xff,  0xff,0x00,0x00,0x00,
+	0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0xff,  0xff,0xff,0x00,0x00,
+	0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0xff,  0xff,0xff,0xff,0x00,
+};
+
+uchar*
+defmask(uchar *ip)
+{
+	return classmask[ip[IPv4off]>>6];
+}
+
+void
+maskip(uchar *from, uchar *mask, uchar *to)
+{
+	int i;
+
+	for(i = 0; i < IPaddrlen; i++)
+		to[i] = from[i] & mask[i];
+}