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, 27 insertions, 80 deletions

diff --git a/epan/dissectors/packet-udp.c b/epan/dissectors/packet-udp.c
index 1b170f817b..ce4ad54507 100644
--- a/epan/dissectors/packet-udp.c
+++ b/epan/dissectors/packet-udp.c
@@ -93,13 +93,9 @@ static header_field_info hfi_udp_checksum_calculated UDP_HFI_INIT =
 { "Calculated Checksum", "udp.checksum_calculated", FT_UINT16, BASE_HEX, NULL, 0x0,
   "The expected UDP checksum field as calculated from the UDP packet", HFILL };
 
-static header_field_info hfi_udp_checksum_good UDP_HFI_INIT =
-{ "Good Checksum", "udp.checksum_good", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
-  "True: checksum matches packet content; False: doesn't match content or not checked", HFILL };
-
-static header_field_info hfi_udp_checksum_bad UDP_HFI_INIT =
-{ "Bad Checksum", "udp.checksum_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
-  "True: checksum doesn't match packet content; False: matches content or not checked", HFILL };
+static header_field_info hfi_udp_checksum_status UDP_HFI_INIT =
+{ "Checksum Status", "udp.checksum.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,
+  NULL, HFILL };
 
 static header_field_info hfi_udp_proc_src_uid UDP_HFI_INIT =
 { "Source process user ID", "udp.proc.srcuid", FT_UINT32, BASE_DEC, NULL, 0x0,
@@ -777,14 +773,13 @@ static void
 dissect(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32 ip_proto)
 {
   proto_tree *udp_tree = NULL;
-  proto_item *ti, *item, *hidden_item;
+  proto_item *ti, *item, *hidden_item, *calc_item;
   proto_item *src_port_item, *dst_port_item, *len_cov_item;
   guint       len;
   guint       reported_len;
   vec_t       cksum_vec[4];
   guint32     phdr[2];
   guint16     computed_cksum;
-  guint16     expected_cksum;
   int         offset = 0;
   e_udphdr   *udph;
   proto_tree *checksum_tree;
@@ -890,28 +885,17 @@ dissect(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32 ip_proto)
   if (udph->uh_sum == 0) {
     /* No checksum supplied in the packet. */
     if (((ip_proto == IP_PROTO_UDP) && (pinfo->src.type == AT_IPv4)) || pinfo->flags.in_error_pkt) {
-      item = proto_tree_add_uint_format_value(udp_tree, hfi_udp_checksum.id, tvb, offset + 6, 2, 0,
-        "0x%04x (none)", 0);
-
-      checksum_tree = proto_item_add_subtree(item, ett_udp_checksum);
-      item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_good, tvb,
-                             offset + 6, 2, FALSE);
-      PROTO_ITEM_SET_GENERATED(item);
-      item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_bad, tvb,
-                             offset + 6, 2, FALSE);
-      PROTO_ITEM_SET_GENERATED(item);
+      proto_tree_add_checksum(udp_tree, tvb, offset + 6, hfi_udp_checksum.id, hfi_udp_checksum_status.id, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NOT_PRESENT);
     } else {
-      item = proto_tree_add_uint_format_value(udp_tree, hfi_udp_checksum.id, tvb, offset + 6, 2, 0,
-        "0x%04x (Illegal)", 0);
+      item = proto_tree_add_uint_format_value(udp_tree, hfi_udp_checksum.id, tvb, offset + 6, 2, 0, "0 (Illegal)");
+      checksum_tree = proto_item_add_subtree(item, ett_udp_checksum);
+
       expert_add_info(pinfo, item, &ei_udp_checksum_zero);
       col_append_str(pinfo->cinfo, COL_INFO, " [ILLEGAL CHECKSUM (0)]");
 
-      checksum_tree = proto_item_add_subtree(item, ett_udp_checksum);
-      item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_good, tvb,
-                             offset + 6, 2, FALSE);
-      PROTO_ITEM_SET_GENERATED(item);
-      item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_bad, tvb,
-                             offset + 6, 2, TRUE);
+      /* XXX - What should this special status be? */
+      item = proto_tree_add_uint(checksum_tree, &hfi_udp_checksum_status, tvb,
+                                        offset + 6, 0, 4);
       PROTO_ITEM_SET_GENERATED(item);
     }
   } else if (!pinfo->fragmented && (len >= reported_len) &&
@@ -953,63 +937,27 @@ dissect(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32 ip_proto)
       }
       SET_CKSUM_VEC_TVB(cksum_vec[3], tvb, offset, udph->uh_sum_cov);
       computed_cksum = in_cksum(&cksum_vec[0], 4);
-      if (computed_cksum == 0) {
-        item = proto_tree_add_uint_format_value(udp_tree, hfi_udp_checksum.id, tvb,
-          offset + 6, 2, udph->uh_sum, "0x%04x [correct]", udph->uh_sum);
 
-        checksum_tree = proto_item_add_subtree(item, ett_udp_checksum);
-        item = proto_tree_add_uint(checksum_tree, &hfi_udp_checksum_calculated,
-                                   tvb, offset + 6, 2, udph->uh_sum);
-        PROTO_ITEM_SET_GENERATED(item);
-        item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_good, tvb,
-                                      offset + 6, 2, TRUE);
-        PROTO_ITEM_SET_GENERATED(item);
-        item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_bad, tvb,
-                                      offset + 6, 2, FALSE);
-        PROTO_ITEM_SET_GENERATED(item);
+      item = proto_tree_add_checksum(udp_tree, tvb, offset+6, hfi_udp_checksum.id, hfi_udp_checksum_status.id, &ei_udp_checksum_bad, pinfo, computed_cksum,
+                                      ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);
+      checksum_tree = proto_item_add_subtree(item, ett_udp_checksum);
+
+      if (computed_cksum != 0) {
+         proto_item_append_text(item, "(maybe caused by \"UDP checksum offload\"?)");
+         col_append_str(pinfo->cinfo, COL_INFO, " [UDP CHECKSUM INCORRECT]");
+         calc_item = proto_tree_add_uint(checksum_tree, &hfi_udp_checksum_calculated,
+                                   tvb, offset + 6, 2, in_cksum_shouldbe(udph->uh_sum, computed_cksum));
       } else {
-        expected_cksum = in_cksum_shouldbe(udph->uh_sum, computed_cksum);
-        item = proto_tree_add_uint_format_value(udp_tree, hfi_udp_checksum.id, tvb,
-                                          offset + 6, 2, udph->uh_sum,
-          "0x%04x [incorrect, should be 0x%04x (maybe caused by \"UDP checksum offload\"?)]", udph->uh_sum,
-          expected_cksum);
-
-        checksum_tree = proto_item_add_subtree(item, ett_udp_checksum);
-        item = proto_tree_add_uint(checksum_tree, &hfi_udp_checksum_calculated,
-                                   tvb, offset + 6, 2, expected_cksum);
-        PROTO_ITEM_SET_GENERATED(item);
-        item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_good, tvb,
-                                      offset + 6, 2, FALSE);
-        PROTO_ITEM_SET_GENERATED(item);
-        item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_bad, tvb,
-                                      offset + 6, 2, TRUE);
-        PROTO_ITEM_SET_GENERATED(item);
-        expert_add_info(pinfo, item, &ei_udp_checksum_bad);
-
-        col_append_str(pinfo->cinfo, COL_INFO, " [UDP CHECKSUM INCORRECT]");
+         calc_item = proto_tree_add_uint(checksum_tree, &hfi_udp_checksum_calculated,
+                                   tvb, offset + 6, 2, udph->uh_sum);
       }
+      PROTO_ITEM_SET_GENERATED(calc_item);
+
     } else {
-      item = proto_tree_add_uint_format_value(udp_tree, hfi_udp_checksum.id, tvb,
-        offset + 6, 2, udph->uh_sum, "0x%04x [validation disabled]", udph->uh_sum);
-      checksum_tree = proto_item_add_subtree(item, ett_udp_checksum);
-      item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_good, tvb,
-                             offset + 6, 2, FALSE);
-      PROTO_ITEM_SET_GENERATED(item);
-      item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_bad, tvb,
-                             offset + 6, 2, FALSE);
-      PROTO_ITEM_SET_GENERATED(item);
+      proto_tree_add_checksum(udp_tree, tvb, offset + 6, hfi_udp_checksum.id, hfi_udp_checksum_status.id, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
     }
   } else {
-    item = proto_tree_add_uint_format_value(udp_tree, hfi_udp_checksum.id, tvb,
-      offset + 6, 2, udph->uh_sum, "0x%04x [unchecked, not all data available]", udph->uh_sum);
-
-    checksum_tree = proto_item_add_subtree(item, ett_udp_checksum);
-    item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_good, tvb,
-                             offset + 6, 2, FALSE);
-    PROTO_ITEM_SET_GENERATED(item);
-    item = proto_tree_add_boolean(checksum_tree, &hfi_udp_checksum_bad, tvb,
-                             offset + 6, 2, FALSE);
-    PROTO_ITEM_SET_GENERATED(item);
+    proto_tree_add_checksum(udp_tree, tvb, offset + 6, hfi_udp_checksum.id, hfi_udp_checksum_status.id, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
   }
 
   /* Skip over header */
@@ -1116,8 +1064,7 @@ proto_register_udp(void)
     &hfi_udp_length,
     &hfi_udp_checksum,
     &hfi_udp_checksum_calculated,
-    &hfi_udp_checksum_good,
-    &hfi_udp_checksum_bad,
+    &hfi_udp_checksum_status,
     &hfi_udp_proc_src_uid,
     &hfi_udp_proc_src_pid,
     &hfi_udp_proc_src_uname,