BGP: Remove redundant text in Path Attributes.

Also added display of lower-order four bits of the Attribute Flags ("unused").

 Current implementation of displaying path attribute flags shows flag description twice if the flag was set.

 For example, with Optional and Length set, the attribute flags were displayed as follows:

             Flags: 0x90, Optional, Length: Optional, Non-transitive, Complete, Extended Length
                 1... .... = Optional: Optional
                 .0.. .... = Transitive: Non-transitive
                 ..0. .... = Partial: Complete
                 ...1 .... = Length: Extended length

 Now they are displayed as follows:

            Flags: 0x90, Optional, Extended-Length, Non-transitive, Complete
                1... .... = Optional: Set
                .0.. .... = Transitive: Not set
                ..0. .... = Partial: Not set
                ...1 .... = Extended-Length: Set
                .... 0000 = Unused: 0x0

Change-Id: Iec3c92ac2383dd3f736598b089a74f0f3c165bae
Reviewed-on: https://code.wireshark.org/review/20732
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 17 insertions, 10 deletions

diff --git a/epan/dissectors/packet-bgp.c b/epan/dissectors/packet-bgp.c
index 81343720e6..c4dfe902d4 100644
--- a/epan/dissectors/packet-bgp.c
+++ b/epan/dissectors/packet-bgp.c
@@ -117,6 +117,7 @@ static dissector_handle_t bgp_handle;
 #define BGP_ATTR_FLAG_TRANSITIVE      0x40
 #define BGP_ATTR_FLAG_PARTIAL         0x20
 #define BGP_ATTR_FLAG_EXTENDED_LENGTH 0x10
+#define BGP_ATTR_FLAG_UNUSED          0x0F
 
 
 /* SSA flags */
@@ -1497,6 +1498,7 @@ static int hf_bgp_update_path_attribute_flags_optional = -1;
 static int hf_bgp_update_path_attribute_flags_transitive = -1;
 static int hf_bgp_update_path_attribute_flags_partial = -1;
 static int hf_bgp_update_path_attribute_flags_extended_length = -1;
+static int hf_bgp_update_path_attribute_flags_unused = -1;
 static int hf_bgp_update_path_attribute_type_code = -1;
 static int hf_bgp_update_path_attribute_length = -1;
 static int hf_bgp_update_path_attribute_next_hop = -1;
@@ -6788,6 +6790,7 @@ dissect_bgp_path_attr(proto_tree *subtree, tvbuff_t *tvb, guint16 path_attr_len,
             &hf_bgp_update_path_attribute_flags_transitive,
             &hf_bgp_update_path_attribute_flags_partial,
             &hf_bgp_update_path_attribute_flags_extended_length,
+            &hf_bgp_update_path_attribute_flags_unused,
             NULL
         };
 
@@ -6811,11 +6814,12 @@ dissect_bgp_path_attr(proto_tree *subtree, tvbuff_t *tvb, guint16 path_attr_len,
 
         ti_flags = proto_tree_add_bitmask(subtree2, tvb, o + i, hf_bgp_update_path_attribute_flags, ett_bgp_attr_flags, path_flags, ENC_NA);
 
-        proto_item_append_text(ti_flags,"%s%s%s%s",
-                 ((bgpa_flags & BGP_ATTR_FLAG_OPTIONAL) == 0) ? ": Well-known" : ": Optional",
-                 ((bgpa_flags & BGP_ATTR_FLAG_TRANSITIVE) == 0) ? ", Non-transitive" : ", Transitive",
-                 ((bgpa_flags & BGP_ATTR_FLAG_PARTIAL) == 0) ? ", Complete" : ", Partial",
-                 ((bgpa_flags & BGP_ATTR_FLAG_EXTENDED_LENGTH) == 0) ? "" : ", Extended Length");
+        if ((bgpa_flags & BGP_ATTR_FLAG_OPTIONAL) == 0)
+            proto_item_append_text(ti_flags, "%s", ", Well-known");
+        if ((bgpa_flags & BGP_ATTR_FLAG_TRANSITIVE) == 0)
+            proto_item_append_text(ti_flags, "%s", ", Non-transitive");
+        if ((bgpa_flags & BGP_ATTR_FLAG_PARTIAL) == 0)
+            proto_item_append_text(ti_flags, "%s", ", Complete");
 
         proto_tree_add_item(subtree2, hf_bgp_update_path_attribute_type_code, tvb, o + i + 1, 1, ENC_BIG_ENDIAN);
 
@@ -8387,16 +8391,19 @@ proto_register_bgp(void)
           NULL, 0x0, NULL, HFILL}},
       { &hf_bgp_update_path_attribute_flags_optional,
         { "Optional", "bgp.update.path_attribute.flags.optional", FT_BOOLEAN, 8,
-          TFS(&tfs_optional_wellknown), BGP_ATTR_FLAG_OPTIONAL, NULL, HFILL}},
+          TFS(&tfs_set_notset), BGP_ATTR_FLAG_OPTIONAL, NULL, HFILL}},
       { &hf_bgp_update_path_attribute_flags_transitive,
         { "Transitive", "bgp.update.path_attribute.flags.transitive", FT_BOOLEAN, 8,
-          TFS(&tfs_transitive_non_transitive), BGP_ATTR_FLAG_TRANSITIVE, NULL, HFILL}},
+          TFS(&tfs_set_notset), BGP_ATTR_FLAG_TRANSITIVE, NULL, HFILL}},
       { &hf_bgp_update_path_attribute_flags_partial,
         { "Partial", "bgp.update.path_attribute.flags.partial", FT_BOOLEAN, 8,
-          TFS(&tfs_partial_complete), BGP_ATTR_FLAG_PARTIAL, NULL, HFILL}},
+          TFS(&tfs_set_notset), BGP_ATTR_FLAG_PARTIAL, NULL, HFILL}},
       { &hf_bgp_update_path_attribute_flags_extended_length,
-        { "Length", "bgp.update.path_attribute.flags.extended_length", FT_BOOLEAN, 8,
-          TFS(&tfs_extended_regular_length), BGP_ATTR_FLAG_EXTENDED_LENGTH, NULL, HFILL}},
+        { "Extended-Length", "bgp.update.path_attribute.flags.extended_length", FT_BOOLEAN, 8,
+          TFS(&tfs_set_notset), BGP_ATTR_FLAG_EXTENDED_LENGTH, NULL, HFILL}},
+      { &hf_bgp_update_path_attribute_flags_unused,
+        { "Unused", "bgp.update.path_attribute.flags.unused", FT_UINT8, BASE_HEX,
+          NULL, BGP_ATTR_FLAG_UNUSED, NULL, HFILL}},
       { &hf_bgp_update_path_attribute_type_code,
         { "Type Code", "bgp.update.path_attribute.type_code", FT_UINT8, BASE_DEC,
           VALS(bgpattr_type), 0x0, NULL, HFILL}},