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

6 files changed, 162 insertions, 89 deletions

diff --git a/epan/Makefile.am b/epan/Makefile.am
index e76001aba4..42a8bc553f 100644
--- a/epan/Makefile.am
+++ b/epan/Makefile.am
@@ -2,7 +2,7 @@
 # Automake file for the EPAN library
 # (Ethereal Protocol ANalyzer Library)
 #
-# $Id: Makefile.am,v 1.37 2004/03/04 08:26:20 jmayer Exp $
+# $Id: Makefile.am,v 1.38 2004/03/06 03:25:10 guy Exp $
 #
 # Ethereal - Network traffic analyzer
 # By Gerald Combs <gerald@ethereal.com>
@@ -36,6 +36,8 @@ include Makefile.common
 INCLUDES = -I$(srcdir)/..
 
 libethereal_a_SOURCES = \
+	addr_and_mask.c		\
+	addr_and_mask.h		\
 	atalk-utils.c		\
 	atalk-utils.h		\
 	bitswap.c		\
diff --git a/epan/Makefile.nmake b/epan/Makefile.nmake
index 8ed9981cff..9fe26533b2 100644
--- a/epan/Makefile.nmake
+++ b/epan/Makefile.nmake
@@ -1,7 +1,7 @@
 ## Makefile for building ethereal.exe with Microsoft C and nmake
 ## Use: $(MAKE) /$(MAKEFLAGS) -f makefile.nmake
 #
-# $Id: Makefile.nmake,v 1.35 2004/03/02 18:55:30 ulfl Exp $
+# $Id: Makefile.nmake,v 1.36 2004/03/06 03:25:10 guy Exp $
 
 include ..\config.nmake
 
@@ -35,7 +35,8 @@ DISSECTOR_SUPPORT_OBJECTS = $(DISSECTOR_SUPPORT_OBJECTS:../=)
 	$(CC) $(CVARSDLL) $(CFLAGS) -Fd.\ -c $(DISSECTOR_SUPPORT_SRC)
  	$(CC) $(CVARSDLL) $(CFLAGS) -Fd.\ -c $<
 
-OBJECTS=atalk-utils.obj	\
+OBJECTS=addr_and_mask.obj \
+	atalk-utils.obj	\
 	bitswap.obj	\
 	circuit.obj     \
 	column-utils.obj \
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;
+}
diff --git a/epan/addr_and_mask.h b/epan/addr_and_mask.h
new file mode 100644
index 0000000000..c05f335370
--- /dev/null
+++ b/epan/addr_and_mask.h
@@ -0,0 +1,45 @@
+/* addr_and_mask.h
+ * Declarations of 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.h,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.
+ */
+
+#ifndef __ADDR_AND_MASK_H__
+#define __ADDR_AND_MASK_H__
+
+/*
+ * These routines return PREFIX_LEN_OK on success, PREFIX_LEN_TOO_LONG if
+ * the prefix length is too long, and PREFIX_LEN_ZERO if the prefix length
+ * is 0.
+ */
+
+#define PREFIX_LEN_OK		0
+#define PREFIX_LEN_TOO_LONG	1
+#define PREFIX_LEN_ZERO		2
+
+extern int ipv4_addr_and_mask(tvbuff_t *tvb, int offset, guint8 *addr,
+    guint32 prefix_len);
+
+extern int ipv6_addr_and_mask(tvbuff_t *tvb, int offset,
+    struct e_in6_addr *addr, guint32 prefix_len);
+
+#endif /* __ADDR_AND_MASK_H__  */
diff --git a/packet-bgp.c b/packet-bgp.c
index cafc8c4d74..bbda8b599c 100644
--- a/packet-bgp.c
+++ b/packet-bgp.c
@@ -2,7 +2,7 @@
  * Routines for BGP packet dissection.
  * Copyright 1999, Jun-ichiro itojun Hagino <itojun@itojun.org>
  *
- * $Id: packet-bgp.c,v 1.86 2004/03/06 02:26:31 guy Exp $
+ * $Id: packet-bgp.c,v 1.87 2004/03/06 03:25:09 guy Exp $
  *
  * Supports:
  * RFC1771 A Border Gateway Protocol 4 (BGP-4)
@@ -56,6 +56,7 @@
 #endif
 
 #include <epan/packet.h>
+#include <epan/addr_and_mask.h>
 #include "packet-bgp.h"
 #include "packet-ipv6.h"
 #include "packet-frame.h"
@@ -368,20 +369,14 @@ decode_prefix4(proto_tree *tree, int hf_addr, tvbuff_t *tvb, gint offset,
     guint8 plen;      /* prefix length                      */
     int    length;    /* number of octets needed for prefix */
 
-    /* snarf length */
+    /* snarf length and prefix */
     plen = tvb_get_guint8(tvb, offset);
-    if (plen > 32 || plen == 0) {
-	proto_tree_add_text(tree, tvb, offset, 1, "%s length %u invalid",
+    length = ipv4_addr_and_mask(tvb, offset + 1, ip_addr.addr_bytes, plen);
+    if (length < 0) {
+	proto_tree_add_text(tree, tvb, offset, 1, "%s length %u invalid (> 32)",
 	    tag, plen);
 	return -1;
     }
-    length = (plen + 7) / 8;
-
-    /* snarf prefix */
-    memset((void *)&ip_addr, 0, sizeof(ip_addr));
-    tvb_memcpy(tvb, ip_addr.addr_bytes, offset + 1, length);
-    if (plen % 8)
-	ip_addr.addr_bytes[length - 1] &= ((0xff00 >> (plen % 8)) & 0xff);
 
     /* put prefix into protocol tree */
     ti = proto_tree_add_text(tree, tvb, offset,
@@ -413,20 +408,14 @@ decode_prefix6(proto_tree *tree, int hf_addr, tvbuff_t *tvb, gint offset,
     int               plen;     /* prefix length                      */
     int               length;   /* number of octets needed for prefix */
 
-    /* snarf length */
+    /* snarf length and prefix */
     plen = tvb_get_guint8(tvb, offset);
-    if (plen > 128 || plen == 0) {
+    length = ipv6_addr_and_mask(tvb, offset + 1, &addr, plen);
+    if (length < 0) {
 	proto_tree_add_text(tree, tvb, offset, 1, "%s length %u invalid",
 	    tag, plen);
 	return -1;
     }
-    length = (plen + 7) / 8;
-
-    /* snarf prefix */
-    memset(&addr, 0, sizeof(addr));
-    tvb_memcpy(tvb, (guint8 *)&addr, offset + 1, length);
-    if (plen % 8)
-	addr.s6_addr[length - 1] &= ((0xff00 >> (plen % 8)) & 0xff);
 
     /* put prefix into protocol tree */
     ti = proto_tree_add_text(tree, tvb, offset,
@@ -663,19 +652,14 @@ decode_prefix_MP(proto_tree *tree, int hf_addr4, int hf_addr6,
                 return -1;
             }
             plen -= (labnum * 3*8);
-            if (plen > 32 || plen == 0) {
+            length = ipv4_addr_and_mask(tvb, offset, ip4addr.addr_bytes, plen);
+            if (length < 0) {
                 proto_tree_add_text(tree, tvb, start_offset, 1,
                         "%s IPv4 prefix length %u invalid",
                         tag, plen + (labnum * 3*8));
                 return -1;
             }
 
-            length = (plen + 7) / 8;
-            memset((void *)&ip4addr, 0, sizeof(ip4addr));
-            tvb_memcpy(tvb, (void *)ip4addr.addr_bytes, offset, length);
-            if (plen % 8)
-                ip4addr.addr_bytes[length - 1] &= ((0xff00 >> (plen % 8)) & 0xff);
-
             ti = proto_tree_add_text(tree, tvb, start_offset,
                     (offset + 1 + length) - start_offset,
                     "Label Stack=%s IP=%s/%u",
@@ -718,19 +702,14 @@ decode_prefix_MP(proto_tree *tree, int hf_addr4, int hf_addr6,
             switch (rd_type) {
 
             case FORMAT_AS2_LOC: /* Code borrowed from the decode_prefix4 function */
-                if (plen > 32 || plen == 0) {
+                length = ipv4_addr_and_mask(tvb, offset + 8, ip4addr.addr_bytes, plen);
+                if (length < 0) {
                     proto_tree_add_text(tree, tvb, start_offset, 1,
                             "%s IPv4 prefix length %u invalid",
                             tag, plen + (labnum * 3*8) + 8*8);
                     return -1;
                 }
 
-                length = (plen + 7) / 8;
-                memset(ip4addr.addr_bytes, 0, 4);
-                tvb_memcpy(tvb, ip4addr.addr_bytes, offset + 8, length);
-                if (plen % 8)
-                    ip4addr.addr_bytes[length - 1] &= ((0xff00 >> (plen % 8)) & 0xff);
-
                 ti = proto_tree_add_text(tree, tvb, start_offset,
                         (offset + 8 + length) - start_offset,
                         "Label Stack=%s RD=%u:%u, IP=%s/%u",
@@ -753,19 +732,14 @@ decode_prefix_MP(proto_tree *tree, int hf_addr4, int hf_addr6,
             case FORMAT_IP_LOC: /* Code borrowed from the decode_prefix4 function */
                 tvb_memcpy(tvb, ip4addr.addr_bytes, offset + 2, 4);
 
-                if (plen > 32 || plen == 0) {
+                length = ipv4_addr_and_mask(tvb, offset + 8, ip4addr2.addr_bytes, plen);
+                if (length < 0) {
                         proto_tree_add_text(tree, tvb, start_offset, 1,
                                 "%s IPv4 prefix length %u invalid",
                                 tag, plen + (labnum * 3*8) + 8*8);
                         return -1;
                 }
 
-                length = (plen + 7) / 8;
-                memset((void *)&ip4addr2, 0, sizeof(ip4addr2));
-                tvb_memcpy(tvb, ip4addr2.addr_bytes, offset + 8, length);
-                if (plen % 8)
-                    ip4addr2.addr_bytes[length - 1] &= ((0xff00 >> (plen % 8)) & 0xff);
-
                 ti = proto_tree_add_text(tree, tvb, start_offset,
                         (offset + 8 + length) - start_offset,
                         "Label Stack=%s RD=%s:%u, IP=%s/%u",
@@ -815,18 +789,13 @@ decode_prefix_MP(proto_tree *tree, int hf_addr4, int hf_addr6,
             }
             plen -= (labnum * 3*8);
 
-            if (plen > 128 || plen == 0) {
+            length = ipv6_addr_and_mask(tvb, offset, &ip6addr, plen);
+            if (length < 0) {
                 proto_tree_add_text(tree, tvb, start_offset, 1,
                         "%s IPv6 prefix length %u invalid", tag, plen);
                 return -1;
             }
 
-	    length = (plen + 7) / 8;
-	    memset(ip6addr.u6_addr.u6_addr8, 0, 16);
-	    tvb_memcpy(tvb, ip6addr.u6_addr.u6_addr8, offset, length);
-	    if (plen % 8)
-		ip6addr.u6_addr.u6_addr8[length - 1] &= ((0xff00 >> (plen % 8)) & 0xff);
-
 	    ti = proto_tree_add_text(tree, tvb, start_offset,
 		 (offset + length) - start_offset,
                  "Label Stack=%s, IP=%s/%u",
@@ -861,19 +830,14 @@ decode_prefix_MP(proto_tree *tree, int hf_addr4, int hf_addr6,
             switch (rd_type) {
 
             case FORMAT_AS2_LOC:
-                if (plen > 128 || plen == 0) {
+                length = ipv6_addr_and_mask(tvb, offset + 8, &ip6addr, plen);
+                if (length < 0) {
                     proto_tree_add_text(tree, tvb, start_offset, 1,
                             "%s IPv6 prefix length %u invalid",
                             tag, plen + (labnum * 3*8) + 8*8);
                     return -1;
                 }
 
-                length = (plen + 7) / 8;
-                memset(ip6addr.u6_addr.u6_addr8, 0, 16);
-                tvb_memcpy(tvb, ip6addr.u6_addr.u6_addr8, offset + 8, length);
-                if (plen % 8)
-                    ip6addr.u6_addr.u6_addr8[length - 1] &= ((0xff00 >> (plen % 8)) & 0xff);
-
                 ti = proto_tree_add_text(tree, tvb, start_offset,
                         (offset + 8 + length) - start_offset,
                         "Label Stack=%s RD=%u:%u, IP=%s/%u",
@@ -887,17 +851,13 @@ decode_prefix_MP(proto_tree *tree, int hf_addr4, int hf_addr6,
             case FORMAT_IP_LOC: 
                 tvb_memcpy(tvb, ip4addr.addr_bytes, offset + 2, 4);
 
-                if (plen > 128 || plen == 0) {
+                length = ipv6_addr_and_mask(tvb, offset + 8, &ip6addr, plen);
+                if (length < 0) {
                     proto_tree_add_text(tree, tvb, start_offset, 1,
                             "%s IPv6 prefix length %u invalid",
                             tag, plen + (labnum * 3*8) + 8*8);
                     return -1;
                 }
-                length = (plen + 7) / 8;
-                memset(ip6addr.u6_addr.u6_addr8, 0, 16);
-                tvb_memcpy(tvb, ip6addr.u6_addr.u6_addr8, offset + 8, length);
-                if (plen % 8)
-                    ip6addr.u6_addr.u6_addr8[length - 1] &= ((0xff00 >> (plen % 8)) & 0xff);
 
                 ti = proto_tree_add_text(tree, tvb, start_offset,
                         (offset + 8 + length) - start_offset,
diff --git a/packet-eigrp.c b/packet-eigrp.c
index efcf4a1c52..a76d021607 100644
--- a/packet-eigrp.c
+++ b/packet-eigrp.c
@@ -2,7 +2,7 @@
  * Routines for EIGRP dissection
  * Copyright 2000, Paul Ionescu <paul@acorp.ro>
  *
- * $Id: packet-eigrp.c,v 1.26 2004/03/06 02:20:55 guy Exp $
+ * $Id: packet-eigrp.c,v 1.27 2004/03/06 03:25:09 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -32,6 +32,7 @@
 #include <epan/resolv.h>
 
 #include <epan/atalk-utils.h>
+#include <epan/addr_and_mask.h>
 #include "ipproto.h"
 #include "packet-ipx.h"
 
@@ -307,7 +308,8 @@ static void dissect_eigrp_nms (tvbuff_t *tvb, proto_tree *tree, proto_item *ti)
 
 static void dissect_eigrp_ip_int (tvbuff_t *tvb, proto_tree *tree, proto_item *ti)
 {
-	guint8 ip_addr[4],length,addr_len;
+	guint8 ip_addr[4],length;
+	int addr_len;
 
 	tvb_memcpy(tvb,ip_addr,0,4);
 	proto_tree_add_text (tree,tvb,0,4, "Next Hop    = %s",ip_to_str(ip_addr));
@@ -319,21 +321,14 @@ static void dissect_eigrp_ip_int (tvbuff_t *tvb, proto_tree *tree, proto_item *t
 	proto_tree_add_text (tree,tvb,17,1,"Load        = %u",tvb_get_guint8(tvb,17));
 	proto_tree_add_text (tree,tvb,18,2,"Reserved ");
 	length=tvb_get_guint8(tvb,20);
-	if (length > 32) {
+	/* XXX - the EIGRP page whose URL appears at the top says this
+	   field is 24 bits; what if the prefix length is > 24? */
+	addr_len=ipv4_addr_and_mask (tvb,21,ip_addr,length);
+	if (addr_len < 0) {
 	    proto_tree_add_text (tree,tvb,20,1,"Prefix length = %u (invalid, must be <= 32)",length);
 	    proto_item_append_text (ti,"  [Invalid prefix length %u > 32]",length);
-	} else if (length == 0) {
-	    proto_tree_add_text (tree,tvb,20,1,"Prefix length = %u (invalid, must be > 0)",length);
-	    proto_item_append_text (ti,"  [Invalid prefix length %u]",length);
 	} else {
 	    proto_tree_add_text (tree,tvb,20,1,"Prefix Length = %u",length);
-	    addr_len=(length+7)/8;
-	    ip_addr[0]=ip_addr[1]=ip_addr[2]=ip_addr[3]=0;
-	    /* XXX - the EIGRP page whose URL appears at the top says this
-	       field is 24 bits; what if the prefix length is > 24? */
-	    tvb_memcpy(tvb,ip_addr,21,addr_len);
-	    if (length%8)
-		ip_addr[addr_len - 1] &= ((0xff00 >> (length % 8)) & 0xff);
 	    proto_tree_add_text (tree,tvb,21,addr_len,"Destination = %s",ip_to_str(ip_addr));
 	    proto_item_append_text (ti,"  =   %s/%u%s",ip_to_str(ip_addr),length,((tvb_get_ntohl(tvb,4)==0xffffffff)?" - Destination unreachable":""));
 	}
@@ -341,7 +336,8 @@ static void dissect_eigrp_ip_int (tvbuff_t *tvb, proto_tree *tree, proto_item *t
 
 static void dissect_eigrp_ip_ext (tvbuff_t *tvb, proto_tree *tree, proto_item *ti)
 {
-	guint8 ip_addr[4],length,addr_len;
+	guint8 ip_addr[4],length;
+	int addr_len;
 
 	tvb_memcpy(tvb,ip_addr,0,4);
 	proto_tree_add_text (tree,tvb,0,4,"Next Hop = %s",ip_to_str(ip_addr));
@@ -362,21 +358,14 @@ static void dissect_eigrp_ip_ext (tvbuff_t *tvb, proto_tree *tree, proto_item *t
 	proto_tree_add_text (tree,tvb,37,1,"Load = %u",tvb_get_guint8(tvb,37));
 	proto_tree_add_text (tree,tvb,38,2,"Reserved ");
 	length=tvb_get_guint8(tvb,40);
-	if (length > 32) {
+	/* XXX - the EIGRP page whose URL appears at the top says this
+	   field is 24 bits; what if the prefix length is > 24? */
+	addr_len=ipv4_addr_and_mask (tvb,41,ip_addr,length);
+	if (addr_len < 0) {
 	    proto_tree_add_text (tree,tvb,40,1,"Prefix length = %u (invalid, must be <= 32)",length);
 	    proto_item_append_text (ti,"  [Invalid prefix length %u > 32]",length);
-	} else if (length == 0) {
-	    proto_tree_add_text (tree,tvb,40,1,"Prefix length = %u (invalid, must be > 0)",length);
-	    proto_item_append_text (ti,"  [Invalid prefix length %u]",length);
 	} else {
 	    proto_tree_add_text (tree,tvb,40,1,"Prefix Length = %u",length);
-	    addr_len=(length+7)/8;
-	    ip_addr[0]=ip_addr[1]=ip_addr[2]=ip_addr[3]=0;
-	    /* XXX - the EIGRP page whose URL appears at the top says this
-	       field is 24 bits; what if the prefix length is > 24? */
-	    tvb_memcpy(tvb,ip_addr,41,addr_len);
-	    if (length%8)
-		ip_addr[addr_len - 1] &= ((0xff00 >> (length % 8)) & 0xff);
 	    proto_tree_add_text (tree,tvb,41,addr_len,"Destination = %s",ip_to_str(ip_addr));
 	    proto_item_append_text (ti,"  =   %s/%u%s",ip_to_str(ip_addr),length,((tvb_get_ntohl(tvb,4)==0xffffffff)?" - Destination unreachable":""));
 	}