Add routines to process IPv{4,6}-address-and-prefix-length pairs,

masking out the appropriate bits in the address.

Use them in the BGP and EIGRP dissectors.

svn path=/trunk/; revision=10327

1 files changed, 76 insertions, 0 deletions

diff --git a/epan/addr_and_mask.c b/epan/addr_and_mask.c
new file mode 100644
index 0000000000..73cd0b015b
--- /dev/null
+++ b/epan/addr_and_mask.c
@@ -0,0 +1,76 @@
+/* addr_and_mask.c
+ * Routines to fetch IPv4 and IPv6 addresses from a tvbuff and then mask
+ * out bits other than those covered by a prefix length
+ *
+ * $Id: addr_and_mask.c,v 1.1 2004/03/06 03:25:10 guy Exp $
+ *
+ * Ethereal - Network traffic analyzer
+ * By Gerald Combs <gerald@ethereal.com>
+ * Copyright 1998 Gerald Combs
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "tvbuff.h"
+#include "ipv6-utils.h"
+#include "addr_and_mask.h"
+
+/*
+ * These routines return the length of the address in bytes on success
+ * and -1 if the prefix length is too long.
+ */
+
+int
+ipv4_addr_and_mask(tvbuff_t *tvb, int offset, guint8 *addr, guint32 prefix_len)
+{
+	guint32 addr_len;
+
+	if (prefix_len > 32)
+		return -1;
+
+	addr_len = (prefix_len + 7) / 8;
+	memset(addr, 0, 4);
+	tvb_memcpy(tvb, addr, offset, addr_len);
+	if (prefix_len % 8)
+		addr[addr_len - 1] &= ((0xff00 >> (prefix_len % 8)) & 0xff);
+	return addr_len;
+}
+
+int
+ipv6_addr_and_mask(tvbuff_t *tvb, int offset, struct e_in6_addr *addr,
+    guint32 prefix_len)
+{
+	guint32 addr_len;
+
+	if (prefix_len > 128)
+		return -1;
+
+	addr_len = (prefix_len + 7) / 8;
+	memset(addr->u6_addr.u6_addr8, 0, 16);
+	tvb_memcpy(tvb, addr->u6_addr.u6_addr8, offset, addr_len);
+	if (prefix_len % 8) {
+		addr->u6_addr.u6_addr8[addr_len - 1] &=
+		    ((0xff00 >> (prefix_len % 8)) & 0xff);
+	}
+
+	return addr_len;
+}