Add entries for traceroute requests and responses to the value_string

table for IGMP packet types (we treat requests as "Query or Request", as
the type doesn't say which it is).

Base the query vs. request decision on the reported length of the
packet, not the captured length.

Checksum the packet only if it's not fragmented and the captured length
is greater than or equal to the amount to be checksummed, and, for
requests where we don't wire in the length to be checksummed, base it on
the reported length of the packet, not the captured length.

svn path=/trunk/; revision=3683

1 files changed, 44 insertions, 24 deletions

diff --git a/packet-igmp.c b/packet-igmp.c
index 8e60d21263..f093b4a7db 100644
--- a/packet-igmp.c
+++ b/packet-igmp.c
@@ -1,7 +1,7 @@
 /* packet-igmp.c   2001 Ronnie Sahlberg <rsahlber@bigpond.net.au>
  * Routines for IGMP packet disassembly
  *
- * $Id: packet-igmp.c,v 1.10 2001/07/11 04:02:51 guy Exp $
+ * $Id: packet-igmp.c,v 1.11 2001/07/11 04:24:34 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -175,9 +175,7 @@ static int ett_mtrace_block = -1;
 #define IGMP_V1_PIM_ROUTING_MESSAGE	0x14
 #define IGMP_V2_MEMBERSHIP_REPORT	0x16
 #define IGMP_V2_LEAVE_GROUP		0x17
-#define IGMP_V1_TRACEROUTE_RESPONSE	0x1e
 #define IGMP_TRACEROUTE_RESPONSE        0x1e
-#define IGMP_V1_TRACEROUTE_MESSAGE	0x1f
 #define IGMP_TRACEROUTE_QUERY_REQ       0x1f
 #define IGMP_V3_MEMBERSHIP_REPORT	0x22
 #define IGMP_TYPE_0x23			0x23
@@ -203,6 +201,8 @@ static const value_string commands[] = {
 	{IGMP_V1_PIM_ROUTING_MESSAGE,	"PIM Routing Message"		},
 	{IGMP_V2_MEMBERSHIP_REPORT,	"Membership Report"		},
 	{IGMP_V2_LEAVE_GROUP,		"Leave Group"			},
+	{IGMP_TRACEROUTE_RESPONSE,	"Traceroute Response"		},
+	{IGMP_TRACEROUTE_QUERY_REQ,	"Traceroute Query or Request"	},
 	{IGMP_V3_MEMBERSHIP_REPORT,	"Membership Report"		},
 	{0,		NULL}
 };
@@ -305,23 +305,43 @@ static const value_string mtrace_fwd_code_vals[] = {
 	proto_tree_add_uint(tree, hf_type, tvb, offset, 1, type);	\
 	offset += 1;
 
-static void igmp_checksum(proto_tree *tree,tvbuff_t *tvb, int len)
+static void igmp_checksum(proto_tree *tree, tvbuff_t *tvb, packet_info *pinfo,
+    guint len)
 {
-	guint16 cksum,hdrcksum;
+	guint16 cksum, hdrcksum;
 	vec_t cksum_vec[1];
 
-	cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, len);
-	cksum_vec[0].len = len;
-
-	hdrcksum = tvb_get_ntohs(tvb, 2);
-	cksum = in_cksum(&cksum_vec[0],1);
-
-	if (cksum==0) {
-		proto_tree_add_uint_format(tree, hf_checksum, tvb, 2, 2, hdrcksum, "Header checksum: 0x%04x (correct)", hdrcksum);
-	} else {
-		proto_tree_add_item_hidden(tree, hf_checksum_bad, tvb, 2, 2, TRUE);
-		proto_tree_add_uint_format(tree, hf_checksum, tvb, 2, 2, hdrcksum, "Header checksum: 0x%04x (incorrect, should be 0x%04x)", hdrcksum,in_cksum_shouldbe(hdrcksum,cksum));
+	if (len == 0) {
+		/*
+		 * Checksum the entire IGMP packet.
+		 */
+		len = tvb_reported_length(tvb);
 	}
+	
+	hdrcksum = tvb_get_ntohs(tvb, 2);
+	if (!pinfo->fragmented && tvb_length(tvb) >= len) {
+		/*
+		 * The packet isn't part of a fragmented datagram and isn't
+		 * truncated, so we can checksum it.
+		 */
+		cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, len);
+		cksum_vec[0].len = len;
+
+		cksum = in_cksum(&cksum_vec[0],1);
+
+		if (cksum == 0) {
+			proto_tree_add_uint_format(tree, hf_checksum,
+			    tvb, 2, 2, hdrcksum,
+			    "Header checksum: 0x%04x (correct)", hdrcksum);
+		} else {
+			proto_tree_add_item_hidden(tree, hf_checksum_bad,
+			    tvb, 2, 2, TRUE);
+			proto_tree_add_uint_format(tree, hf_checksum,
+			    tvb, 2, 2, hdrcksum,
+			    "Header checksum: 0x%04x (incorrect, should be 0x%04x)", hdrcksum,in_cksum_shouldbe(hdrcksum,cksum));
+		}
+	} else
+		proto_tree_add_uint(tree, hf_checksum, tvb, 2, 2, hdrcksum);
 
 	return;
 }
@@ -476,7 +496,7 @@ dissect_igmp_v3_response(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, in
 	offset += 1;
 
 	/* checksum */
-	igmp_checksum(tree, tvb, pinfo->iplen-pinfo->iphdrlen*4);
+	igmp_checksum(tree, tvb, pinfo, 0);
 	offset +=2;
 
 	/* skip reserved field */
@@ -506,7 +526,7 @@ dissect_igmp_v3_query(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int t
 	offset = dissect_v3_max_resp(tvb, pinfo, tree, offset);
 
 	/* checksum */
-	igmp_checksum(tree, tvb, pinfo->iplen-pinfo->iphdrlen*4);
+	igmp_checksum(tree, tvb, pinfo, 0);
 	offset += 2;
 
 	/* group address */
@@ -547,7 +567,7 @@ dissect_igmp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, i
 	offset += 1;
 
 	/* checksum */
-	igmp_checksum(tree, tvb, 8);
+	igmp_checksum(tree, tvb, pinfo, 8);
 	offset += 2;
 
 	/* group address */
@@ -567,7 +587,7 @@ dissect_igmp_v1(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, i
 	offset += 1;
 
 	/* checksum */
-	igmp_checksum(tree, tvb, 8);
+	igmp_checksum(tree, tvb, pinfo, 8);
 	offset += 2;
 
 	/* group address */
@@ -599,7 +619,7 @@ dissect_igmp_v0(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, i
 	offset += 1;
 
 	/* checksum */
-	igmp_checksum(tree, tvb, 20);
+	igmp_checksum(tree, tvb, pinfo, 20);
 	offset += 2;
 
 	/* identifier */
@@ -637,7 +657,7 @@ dissect_igmp_mtrace(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int typ
 		snprintf(buf, sizeof buf, ", %d block%s", i, plurality(i, "", "s"));
 		typestr = "Traceroute Response";
 		blocks = buf;
-	} else if (tvb_length_remaining(tvb, offset) == IGMP_TRACEROUTE_HDR_LEN)
+	} else if (tvb_reported_length_remaining(tvb, offset) == IGMP_TRACEROUTE_HDR_LEN)
 		typestr = "Traceroute Query";
 	else
 		typestr = "Traceroute Request";
@@ -655,8 +675,8 @@ dissect_igmp_mtrace(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int typ
 	proto_tree_add_item(tree, hf_mtrace_max_hops, tvb, offset, 1, FALSE);
 	offset += 1;
 
-	/* - 2 since the checksum covers the whole IGMP packet (the entire IP payload) */
-	igmp_checksum(tree, tvb, tvb_length_remaining(tvb, offset - 2));
+	/* checksum */
+	igmp_checksum(tree, tvb, pinfo, 0);
 	offset += 2;
 
 	/* group address to be traced */