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, 38 deletions

diff --git a/epan/dissectors/packet-ositp.c b/epan/dissectors/packet-ositp.c
index 53d7328b75..08c671211d 100644
--- a/epan/dissectors/packet-ositp.c
+++ b/epan/dissectors/packet-ositp.c
@@ -68,7 +68,8 @@ static int hf_cotp_eot_extended = -1;
 static int hf_cotp_parameter_code = -1;
 static int hf_cotp_parameter_length = -1;
 static int hf_cotp_parameter_value = -1;
-static int hf_cotp_atn_extended_checksum = -1;
+static int hf_cotp_atn_extended_checksum16 = -1;
+static int hf_cotp_atn_extended_checksum32 = -1;
 static int hf_cotp_ack_time = -1;
 static int hf_cotp_res_error_rate_target_value = -1;
 static int hf_cotp_res_error_rate_min_accept = -1;
@@ -440,10 +441,8 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset, int vp_length,
   gint32          i                       = 0;
   guint8          tmp_code                = 0;
   guint           tmp_len                 = 0;
-  cksum_status_t  cksum_status;
-  gboolean        checksum_ok             = FALSE;
   guint32         pref_max_tpdu_size;
-  proto_item     *ti, *hidden_item;
+  proto_item     *hidden_item;
 
   while (vp_length != 0) {
     code = tvb_get_guint8(tvb, offset);
@@ -462,6 +461,7 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset, int vp_length,
 
     case VP_ATN_EC_16 : /* ATN */
       if (cotp_decode_atn) {
+        guint16 sum;
         /* if an alternate OSI checksum is present in the currently unprocessed
          * VP section to the checksum algorithm has to know.
          * this may be the case for backward compatible CR TPDU */
@@ -477,12 +477,11 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset, int vp_length,
             i += tmp_len;
           }
         }
-        checksum_ok = check_atn_ec_16(tvb, tpdu_len , offset,
+        sum = check_atn_ec_16(tvb, tpdu_len , offset,
                                       offset_iso8073_checksum,
                                       pinfo->dst.len, (const guint8 *)pinfo->dst.data,
                                       pinfo->src.len, (const guint8 *)pinfo->src.data);
-        ti = proto_tree_add_item(tree, hf_cotp_atn_extended_checksum, tvb, offset, 2, ENC_BIG_ENDIAN);
-        proto_item_append_text(ti, checksum_ok ? " (correct)" : " (incorrect)");
+        proto_tree_add_checksum(tree, tvb, offset, hf_cotp_atn_extended_checksum16, -1, NULL, pinfo, sum, ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_ZERO);
       } else {
         proto_tree_add_bytes_format_value(tree, hf_cotp_parameter_value, tvb, offset, length, NULL, "<not shown>");
       }
@@ -492,6 +491,7 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset, int vp_length,
 
     case VP_ATN_EC_32 : /* ATN */
       if (cotp_decode_atn) {
+        guint32 sum;
         /* if an alternate OSI checksum is present in the currently unprocessed
          * VP section the checksum algorithm has to know.
          * this may be the case for backward compatible CR TPDU */
@@ -507,12 +507,11 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset, int vp_length,
             i += tmp_len;
           }
         }
-        checksum_ok = check_atn_ec_32(tvb, tpdu_len , offset,
+        sum = check_atn_ec_32(tvb, tpdu_len , offset,
                                       offset_iso8073_checksum,
                                       pinfo->dst.len, (const guint8 *)pinfo->dst.data,
                                       pinfo->src.len, (const guint8 *)pinfo->src.data);
-        ti = proto_tree_add_item(tree, hf_cotp_atn_extended_checksum, tvb, offset, 4, ENC_BIG_ENDIAN);
-        proto_item_append_text(ti, checksum_ok ? " (correct)" : " (incorrect)");
+        proto_tree_add_checksum(tree, tvb, offset, hf_cotp_atn_extended_checksum32, -1, NULL, pinfo, sum, ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_ZERO);
       } else {
         proto_tree_add_bytes_format_value(tree, hf_cotp_parameter_value, tvb, offset, length, NULL, "<not shown>");
       }
@@ -691,36 +690,21 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset, int vp_length,
 
     case VP_CHECKSUM:
       offset_iso8073_checksum = offset; /* save ISO 8073 checksum offset for ATN extended checksum calculation */
-      cksum_status = calc_checksum(tvb, 0, tpdu_len,
-                                   tvb_get_ntohs(tvb, offset));
-      switch (cksum_status) {
 
-      default:
-        /*
-         * No checksum present, or not enough of the packet present to
-         * checksum it.
-         */
-        proto_tree_add_item(tree, hf_cotp_checksum, tvb, offset, 2, ENC_BIG_ENDIAN);
-        break;
-
-      case CKSUM_OK:
-        /*
-         * Checksum is correct.
-         */
-        s = tvb_get_ntohs(tvb, offset);
-        proto_tree_add_uint_format_value(tree, hf_cotp_checksum, tvb, offset, 2,
-                            s, "0x%04x (correct)", s);
-        break;
+      if (tvb_get_ntohs(tvb, offset) == 0) {
+        /* No checksum present */
+        proto_tree_add_checksum(tree, tvb, offset, hf_cotp_checksum, -1, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NOT_PRESENT);
+      } else {
+        guint32 calc_c0 = 0, calc_c1 = 0;
 
-      case CKSUM_NOT_OK:
-        /*
-         * Checksum is not correct.
-         */
-        s = tvb_get_ntohs(tvb, offset);
-        proto_tree_add_uint_format_value(tree, hf_cotp_checksum, tvb, offset, 2,
-                            s, "0x%04x (incorrect)", s);
-        break;
+        if (osi_calc_checksum(tvb, 0, length, &calc_c0, &calc_c1)) {
+            /* Successfully processed checksum, verify it */
+            proto_tree_add_checksum(tree, tvb, offset, hf_cotp_checksum, -1, NULL, pinfo, calc_c0 | calc_c1, ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_ZERO);
+        } else {
+            proto_tree_add_checksum(tree, tvb, offset, hf_cotp_checksum, -1, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
+        }
       }
+
       offset += length;
       vp_length -= length;
       break;
@@ -2338,7 +2322,8 @@ void proto_register_cotp(void)
       { &hf_cotp_parameter_code, { "Parameter code", "cotp.parameter_code", FT_UINT8, BASE_HEX, VALS(tp_vpart_type_vals), 0x0, NULL, HFILL }},
       { &hf_cotp_parameter_length, { "Parameter length", "cotp.parameter_length", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
       { &hf_cotp_parameter_value, { "Parameter value", "cotp.parameter_value", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},
-      { &hf_cotp_atn_extended_checksum, { "ATN extended checksum", "cotp.atn_extended_checksum", FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL }},
+      { &hf_cotp_atn_extended_checksum16, { "ATN extended checksum", "cotp.atn_extended_checksum", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL }},
+      { &hf_cotp_atn_extended_checksum32, { "ATN extended checksum", "cotp.atn_extended_checksum", FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL }},
       { &hf_cotp_ack_time, { "Ack time (ms)", "cotp.ack_time", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},
       { &hf_cotp_res_error_rate_target_value, { "Residual error rate, target value", "cotp.res_error_rate.target_value", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
       { &hf_cotp_res_error_rate_min_accept, { "Residual error rate, minimum acceptable", "cotp.res_error_rate.min_accept", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},