Add proto_tree_add_checksum.

This is an attempt to standardize display/handling of checksum fields for all dissectors.
The main target is for dissectors that do validation, but dissectors that just report the
checksum were also included just to make them easier to find in the future.

Bug: 10620
Bug: 12058
Ping-Bug: 8859
Change-Id: Ia8abd86e42eaf8ed50de6b173409e914b17993bf
Reviewed-on: https://code.wireshark.org/review/16380
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Jeff Morriss <jeff.morriss.ws@gmail.com>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 23 insertions, 67 deletions

diff --git a/epan/dissectors/packet-ip.c b/epan/dissectors/packet-ip.c
index aac46b2cd1..c72b0dbee6 100644
--- a/epan/dissectors/packet-ip.c
+++ b/epan/dissectors/packet-ip.c
@@ -124,8 +124,7 @@ static int hf_ip_ttl = -1;
 static int hf_ip_proto = -1;
 static int hf_ip_checksum = -1;
 static int hf_ip_checksum_calculated = -1;
-static int hf_ip_checksum_good = -1;
-static int hf_ip_checksum_bad = -1;
+static int hf_ip_checksum_status = -1;
 
 /* IP option fields */
 static int hf_ip_opt_type = -1;
@@ -243,7 +242,6 @@ static gint ett_ip_option_qs = -1;
 static gint ett_ip_option_other = -1;
 static gint ett_ip_fragments = -1;
 static gint ett_ip_fragment  = -1;
-static gint ett_ip_checksum = -1;
 static gint ett_ip_opt_type = -1;
 static gint ett_ip_opt_sec_prot_auth_flags = -1;
 static gint ett_unknown_ip_tcp_opt = -1;
@@ -1999,7 +1997,6 @@ dissect_ip_v4(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void*
   guint      hlen, optlen;
   guint16    flags;
   guint16    ipsum;
-  guint16    expected_cksum;
   fragment_head *ipfd_head = NULL;
   tvbuff_t   *next_tvb;
   gboolean   update_col_info = TRUE;
@@ -2008,7 +2005,6 @@ dissect_ip_v4(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void*
   guint32    src32, dst32;
   proto_tree *tree;
   proto_item *item = NULL, *ttl_item;
-  proto_tree *checksum_tree;
   guint16 ttl;
   int bit_offset;
   tree = parent_tree;
@@ -2207,55 +2203,25 @@ dissect_ip_v4(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void*
    */
   if (ip_check_checksum && tvb_bytes_exist(tvb, offset, hlen)&&(!pinfo->flags.in_error_pkt)) {
     ipsum = ip_checksum_tvb(tvb, offset, hlen);
-    if (tree) {
-      if (ipsum == 0) {
-        item = proto_tree_add_uint_format_value(ip_tree, hf_ip_checksum, tvb,
-                                          offset + 10, 2, iph->ip_sum,
-                                          "0x%04x [correct]",
-                                          iph->ip_sum);
-        checksum_tree = proto_item_add_subtree(item, ett_ip_checksum);
-        item = proto_tree_add_uint(checksum_tree, hf_ip_checksum_calculated, tvb,
-                                      offset + 10, 2, iph->ip_sum);
-        PROTO_ITEM_SET_GENERATED(item);
-        item = proto_tree_add_boolean(checksum_tree, hf_ip_checksum_good, tvb,
-                                      offset + 10, 2, TRUE);
-        PROTO_ITEM_SET_GENERATED(item);
-        item = proto_tree_add_boolean(checksum_tree, hf_ip_checksum_bad, tvb,
-                                      offset + 10, 2, FALSE);
-        PROTO_ITEM_SET_GENERATED(item);
-      } else {
-        expected_cksum = in_cksum_shouldbe(iph->ip_sum, ipsum);
-
-        item = proto_tree_add_uint_format_value(ip_tree, hf_ip_checksum, tvb,
-                                          offset + 10, 2, iph->ip_sum,
-                                          "0x%04x "
-                                          "[incorrect, should be 0x%04x "
-                                          "(may be caused by \"IP checksum "
-                                          "offload\"?)]", iph->ip_sum,
-                                          expected_cksum);
-        checksum_tree = proto_item_add_subtree(item, ett_ip_checksum);
-        item = proto_tree_add_uint(checksum_tree, hf_ip_checksum_calculated, tvb,
-                                      offset + 10, 2, expected_cksum);
-        PROTO_ITEM_SET_GENERATED(item);
-        item = proto_tree_add_boolean(checksum_tree, hf_ip_checksum_good, tvb,
-                                      offset + 10, 2, FALSE);
-        PROTO_ITEM_SET_GENERATED(item);
-        item = proto_tree_add_boolean(checksum_tree, hf_ip_checksum_bad, tvb,
-                                      offset + 10, 2, TRUE);
-        PROTO_ITEM_SET_GENERATED(item);
-      }
-    }
-    if (ipsum != 0) {
-      /* Add expert item always (so tap gets called if present);
-         if (tree == NULL) then item will be NULL
-         else item should be from the
-         add_boolean(..., hf_ip_checksum_bad, ...) above */
-      expert_add_info(pinfo, item, &ei_ip_checksum_bad);
+    item = proto_tree_add_checksum(ip_tree, tvb, offset + 10, hf_ip_checksum, hf_ip_checksum_status, &ei_ip_checksum_bad, pinfo, ipsum,
+                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);
+    if (ipsum == 0) {
+      /* XXX - Keeping hf_ip_checksum_calculated field for now.  Doesn't fit into the
+        proto_tree_add_checksum design, but IP is a popular enough dissector that somebody
+        may have a legitimate reason for wanting it filtered */
+      item = proto_tree_add_uint(ip_tree, hf_ip_checksum_calculated, tvb,
+                                    offset + 10, 2, iph->ip_sum);
+      PROTO_ITEM_SET_GENERATED(item);
+    } else {
+      proto_item_append_text(item, "(may be caused by \"IP checksum offload\"?)");
+
+      item = proto_tree_add_uint(ip_tree, hf_ip_checksum_calculated, tvb,
+                                      offset + 10, 2, in_cksum_shouldbe(iph->ip_sum, ipsum));
+      PROTO_ITEM_SET_GENERATED(item);
     }
   } else {
     ipsum = 0;
-    if (tree) {
-      item = proto_tree_add_uint_format_value(ip_tree, hf_ip_checksum, tvb,
+    proto_tree_add_uint_format_value(ip_tree, hf_ip_checksum, tvb,
                                         offset + 10, 2, iph->ip_sum,
                                         "0x%04x [%s]",
                                         iph->ip_sum,
@@ -2264,14 +2230,9 @@ dissect_ip_v4(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void*
                                              "in ICMP error packet" :
                                              "not all data available") :
                                             "validation disabled");
-      checksum_tree = proto_item_add_subtree(item, ett_ip_checksum);
-      item = proto_tree_add_boolean(checksum_tree, hf_ip_checksum_good, tvb,
-                                    offset + 10, 2, FALSE);
-      PROTO_ITEM_SET_GENERATED(item);
-      item = proto_tree_add_boolean(checksum_tree, hf_ip_checksum_bad, tvb,
-                                    offset + 10, 2, FALSE);
-      PROTO_ITEM_SET_GENERATED(item);
-    }
+    item = proto_tree_add_uint(ip_tree, hf_ip_checksum_status, tvb,
+                                    offset + 10, 0, PROTO_CHECKSUM_E_UNVERIFIED);
+    PROTO_ITEM_SET_GENERATED(item);
   }
   src32 = tvb_get_ntohl(tvb, offset + IPH_SRC);
   set_address_tvb(&pinfo->net_src, AT_IPv4, 4, tvb, offset + IPH_SRC);
@@ -2801,13 +2762,9 @@ proto_register_ip(void)
     { "Calculated Checksum", "ip.checksum_calculated", FT_UINT16, BASE_HEX, NULL, 0x0,
         "The expected IP checksum field as calculated from the IP datagram", HFILL }},
 
-    { &hf_ip_checksum_good,
-      { "Good", "ip.checksum_good", FT_BOOLEAN, BASE_NONE,  NULL, 0x0,
-        "True: checksum matches packet content; False: doesn't match content or not checked", HFILL }},
-
-    { &hf_ip_checksum_bad,
-      { "Bad", "ip.checksum_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
-        "True: checksum doesn't match packet content; False: matches content or not checked", HFILL }},
+    { &hf_ip_checksum_status,
+      { "Header checksum status", "ip.checksum.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,
+        NULL, HFILL }},
 
     /* IP options related fields */
     { &hf_ip_opt_type,
@@ -3080,7 +3037,6 @@ proto_register_ip(void)
     &ett_ip_option_other,
     &ett_ip_fragments,
     &ett_ip_fragment,
-    &ett_ip_checksum,
     &ett_ip_opt_type,
     &ett_ip_opt_sec_prot_auth_flags,
     &ett_unknown_ip_tcp_opt,