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, 19 insertions, 51 deletions

diff --git a/epan/dissectors/packet-cdp.c b/epan/dissectors/packet-cdp.c
index fb975fa89a..b61a7097cc 100644
--- a/epan/dissectors/packet-cdp.c
+++ b/epan/dissectors/packet-cdp.c
@@ -53,8 +53,7 @@ void proto_reg_handoff_cdp(void);
 static int proto_cdp = -1;
 static int hf_cdp_version = -1;
 static int hf_cdp_checksum = -1;
-static int hf_cdp_checksum_good = -1;
-static int hf_cdp_checksum_bad = -1;
+static int hf_cdp_checksum_status = -1;
 static int hf_cdp_ttl = -1;
 static int hf_cdp_tlvtype = -1;
 static int hf_cdp_tlvlength = -1;
@@ -271,12 +270,11 @@ static const value_string type_nrgyz_vals[] = {
 static int
 dissect_cdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
 {
-    proto_item *ti, *checksum_item;
-    proto_tree *cdp_tree = NULL, *checksum_tree;
+    proto_item *ti;
+    proto_tree *cdp_tree;
     int         offset   = 0;
     guint16     type;
-    guint16     length, packet_checksum, computed_checksum, data_length;
-    gboolean    checksum_good, checksum_bad;
+    guint16     length, data_length;
     proto_item *tlvi     = NULL;
     proto_tree *tlv_tree = NULL;
     int         real_length;
@@ -289,25 +287,20 @@ dissect_cdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
     col_set_str(pinfo->cinfo, COL_PROTOCOL, "CDP");
     col_clear(pinfo->cinfo, COL_INFO);
 
-    if (tree) {
-        ti = proto_tree_add_item(tree, proto_cdp, tvb, offset, -1, ENC_NA);
-        cdp_tree = proto_item_add_subtree(ti, ett_cdp);
+    ti = proto_tree_add_item(tree, proto_cdp, tvb, offset, -1, ENC_NA);
+    cdp_tree = proto_item_add_subtree(ti, ett_cdp);
 
-        /* CDP header */
-        proto_tree_add_item(cdp_tree, hf_cdp_version, tvb, offset, 1, ENC_BIG_ENDIAN);
-        offset += 1;
+    /* CDP header */
+    proto_tree_add_item(cdp_tree, hf_cdp_version, tvb, offset, 1, ENC_BIG_ENDIAN);
+    offset += 1;
 
-        proto_tree_add_uint_format_value(cdp_tree, hf_cdp_ttl, tvb, offset, 1,
-                                         tvb_get_guint8(tvb, offset),
-                                         "%u seconds",
-                                         tvb_get_guint8(tvb, offset));
-        offset += 1;
-    } else {
-        offset += 2; /* The version/ttl fields from above */
-    }
+    proto_tree_add_uint_format_value(cdp_tree, hf_cdp_ttl, tvb, offset, 1,
+                                        tvb_get_guint8(tvb, offset),
+                                        "%u seconds",
+                                        tvb_get_guint8(tvb, offset));
+    offset += 1;
 
     /* Checksum display & verification code */
-    packet_checksum = tvb_get_ntohs(tvb, offset);
 
     data_length = tvb_reported_length(tvb);
 
@@ -343,29 +336,8 @@ dissect_cdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
         SET_CKSUM_VEC_TVB(cksum_vec[0], tvb, 0, data_length);
     }
 
-    computed_checksum = in_cksum(cksum_vec, 1);
-    checksum_good = (computed_checksum == 0);
-    checksum_bad = !checksum_good;
-    if (checksum_good) {
-        checksum_item = proto_tree_add_uint_format_value(cdp_tree,
-                                                   hf_cdp_checksum, tvb, offset, 2, packet_checksum,
-                                                   "0x%04x [correct]", packet_checksum);
-    } else {
-        checksum_item = proto_tree_add_uint_format_value(cdp_tree,
-                                                   hf_cdp_checksum, tvb, offset, 2, packet_checksum,
-                                                   "0x%04x [incorrect, should be 0x%04x]",
-                                                   packet_checksum,
-                                                   in_cksum_shouldbe(packet_checksum, computed_checksum));
-    }
-
-    checksum_tree = proto_item_add_subtree(checksum_item, ett_cdp_checksum);
-    checksum_item = proto_tree_add_boolean(checksum_tree, hf_cdp_checksum_good,
-                                           tvb, offset, 2, checksum_good);
-    PROTO_ITEM_SET_GENERATED(checksum_item);
-    checksum_item = proto_tree_add_boolean(checksum_tree, hf_cdp_checksum_bad,
-                                           tvb, offset, 2, checksum_bad);
-    PROTO_ITEM_SET_GENERATED(checksum_item);
-
+    proto_tree_add_checksum(cdp_tree, tvb, offset, hf_cdp_checksum, hf_cdp_checksum_status, NULL, pinfo, in_cksum(cksum_vec, 1),
+                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);
     offset += 2;
 
     while (tvb_reported_length_remaining(tvb, offset) != 0) {
@@ -1290,13 +1262,9 @@ proto_register_cdp(void)
         { "Checksum",           "cdp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
           NULL, HFILL }},
 
-        { &hf_cdp_checksum_good,
-          { "Good",       "cdp.checksum_good", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
-            "True: checksum matches packet content; False: doesn't match content or not checked", HFILL }},
-
-        { &hf_cdp_checksum_bad,
-          { "Bad",       "cdp.checksum_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
-            "True: checksum doesn't match packet content; False: matches content or not checked", HFILL }},
+        { &hf_cdp_checksum_status,
+          { "Checksum Status",       "cdp.checksum.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,
+            NULL, HFILL }},
 
         { &hf_cdp_tlvtype,
         { "Type",               "cdp.tlv.type", FT_UINT16, BASE_HEX, VALS(type_vals), 0x0,