Check the checksum on ICMPv6 packets, if possible.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@2759 f5534014-38df-0310-8fa8-9805f1628bb7

diff --git a/packet-icmpv6.c b/packet-icmpv6.c
index 0cc8c9857f96079e2af24f17b066cbf95efadc60..0f390a2f1d36554ede80a6cc495fe5aa76bcd984 100644 (file)
--- a/packet-icmpv6.c
+++ b/packet-icmpv6.c
@@ -1,7 +1,7 @@
 /* packet-icmpv6.c
  * Routines for ICMPv6 packet disassembly
  *
- * $Id: packet-icmpv6.c,v 1.31 2000/11/19 08:53:57 guy Exp $
+ * $Id: packet-icmpv6.c,v 1.32 2000/12/14 21:45:12 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@zing.org>
@@ -54,6 +54,7 @@
 #include "packet-ipv6.h"
 #include "packet-ip.h"
 #include "packet-dns.h"
+#include "in_cksum.h"
 #include "resolv.h"
 
 #ifndef offsetof
@@ -720,12 +721,16 @@ static void
 dissect_icmpv6(const u_char *pd, int offset, frame_data *fd, proto_tree *tree)
 {
     proto_tree *icmp6_tree, *field_tree;
-       proto_item *ti, *tf = NULL;
+    proto_item *ti, *tf = NULL;
     struct icmp6_hdr *dp;
     struct icmp6_nodeinfo *ni = NULL;
     char *codename, *typename;
     char *colcodename, *coltypename;
     int len;
+    guint length, reported_length;
+    vec_t cksum_vec[4];
+    guint32 phdr[2];
+    guint16 cksum, computed_cksum;
 
     OLD_CHECK_DISPLAY_AS_DATA(proto_icmpv6, pd, offset, fd, tree);
 
@@ -923,9 +928,44 @@ dissect_icmpv6(const u_char *pd, int offset, frame_data *fd, proto_tree *tree)
                dp->icmp6_code,
                "Code: 0x%02x", dp->icmp6_code);
        }
-       proto_tree_add_uint(icmp6_tree, hf_icmpv6_checksum, NullTVB,
-           offset + offsetof(struct icmp6_hdr, icmp6_cksum), 2,
-           (guint16)htons(dp->icmp6_cksum));
+       cksum = (guint16)htons(dp->icmp6_cksum);
+       length = pi.captured_len - offset;
+       reported_length = pi.len - offset;
+       if (!pi.fragmented && length >= reported_length) {
+           /* The packet isn't part of a fragmented datagram and isn't
+              truncated, so we can checksum it. */
+
+           /* Set up the fields of the pseudo-header. */
+           cksum_vec[0].ptr = pi.src.data;
+           cksum_vec[0].len = pi.src.len;
+           cksum_vec[1].ptr = pi.dst.data;
+           cksum_vec[1].len = pi.dst.len;
+           cksum_vec[2].ptr = (const guint8 *)&phdr;
+           phdr[0] = htonl(reported_length);
+           phdr[1] = htonl(IP_PROTO_ICMPV6);
+           cksum_vec[2].len = 8;
+           cksum_vec[3].ptr = &pd[offset];
+           cksum_vec[3].len = reported_length;
+           computed_cksum = in_cksum(cksum_vec, 4);
+           if (computed_cksum == 0) {
+               proto_tree_add_uint_format(icmp6_tree, hf_icmpv6_checksum,
+                       NullTVB,
+                       offset + offsetof(struct icmp6_hdr, icmp6_cksum), 2,
+                       cksum,
+                       "Checksum: 0x%04x (correct)", cksum);
+           } else {
+               proto_tree_add_uint_format(icmp6_tree, hf_icmpv6_checksum,
+                       NullTVB,
+                       offset + offsetof(struct icmp6_hdr, icmp6_cksum), 2,
+                       cksum,
+                       "Checksum: 0x%04x (incorrect, should be 0x%04x)",
+                       cksum, in_cksum_shouldbe(cksum, computed_cksum));
+           }
+       } else {
+           proto_tree_add_uint(icmp6_tree, hf_icmpv6_checksum, NullTVB,
+               offset + offsetof(struct icmp6_hdr, icmp6_cksum), 2,
+               cksum);
+       }
 
        /* decode... */
        switch (dp->icmp6_type) {