util.c: Add the `mask62plen' utility function.

The function does the same as `mask2plen' but for IPv6.

Signed-off-by: Florian Forster <octo@leeloo.lan.home.verplant.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/util.c b/util.c
index 784b09b7..526a0611 100644
--- a/util.c
+++ b/util.c
@@ -439,6 +439,35 @@ mask2plen (u_int32_t mask)
 	return (prefix_len);
 }
 
+#ifdef INET6
+int mask62plen(const u_char *mask)
+{
+	u_char bitmasks[] =
+	{
+		0x00, 0x80, 0xc0, 0xe0,
+		0xf0, 0xf8, 0xfc, 0xfe, 0xff
+	};
+	int cidr_len = 0;
+	int byte;
+
+	for (byte = 0; byte < 16; byte++)
+	{
+		int bits;
+
+		for (bits = 0; bits < (sizeof (bitmasks) / sizeof (bitmasks[0])); bits++)
+			if (mask[byte] == bitmasks[bits])
+			{
+				cidr_len += bits;
+				break;
+			}
+
+		if (mask[byte] != 0xff)
+			break;
+	}
+	return (cidr_len);
+}
+#endif /* INET6 */
+
 /* VARARGS */
 void
 error(const char *fmt, ...)