ISIS (LSP): Fix Malformed packet

Coming from fetch too longer bytes...

Rework the display for add some missing field (SubTLV indicator, prefix len) and for prefix IPv4 use the same code like BGP

Issue reported by Garri Djavadyan

Bug:12617
Change-Id: Ib40f1badf8e03fadacfbb0aff1ebd3eab8ca342b
Reviewed-on: https://code.wireshark.org/review/16436
Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 24 insertions, 6 deletions

diff --git a/epan/dissectors/packet-isis-lsp.c b/epan/dissectors/packet-isis-lsp.c
index 8f7198127c..827c6c8b16 100644
--- a/epan/dissectors/packet-isis-lsp.c
+++ b/epan/dissectors/packet-isis-lsp.c
@@ -309,6 +309,8 @@ static int hf_isis_lsp_ext_is_reachability_len = -1;
 static int hf_isis_lsp_ext_is_reachability_value = -1;
 static int hf_isis_lsp_default_metric = -1;
 static int hf_isis_lsp_ext_ip_reachability_distribution = -1;
+static int hf_isis_lsp_ext_ip_reachability_subtlv = -1;
+static int hf_isis_lsp_ext_ip_reachability_prefix_length = -1;
 static int hf_isis_lsp_ext_ip_reachability_subclvs_len = -1;
 static int hf_isis_lsp_ext_ip_reachability_code = -1;
 static int hf_isis_lsp_ext_ip_reachability_len = -1;
@@ -808,7 +810,10 @@ dissect_lsp_ext_ip_reachability_clv(tvbuff_t *tvb, packet_info* pinfo, proto_tre
     guint8     ctrl_info;
     guint      bit_length;
     int        byte_length;
-    guint8     prefix [4];
+    union {
+       guint8 addr_bytes[4];
+       guint32 addr;
+    } prefix;
     address    prefix_addr;
     guint      len,i;
     guint      subclvs_len;
@@ -817,7 +822,7 @@ dissect_lsp_ext_ip_reachability_clv(tvbuff_t *tvb, packet_info* pinfo, proto_tre
     while (length > 0) {
         ctrl_info = tvb_get_guint8(tvb, offset+4);
         bit_length = ctrl_info & 0x3f;
-        byte_length = tvb_get_ipv4_addr_with_prefix_len(tvb, offset+5, prefix, bit_length);
+        byte_length = tvb_get_ipv4_addr_with_prefix_len(tvb, offset+5, prefix.addr_bytes, bit_length);
         if (byte_length == -1) {
             proto_tree_add_expert_format(tree, pinfo, &ei_isis_lsp_short_packet, tvb, offset, -1,
                  "IPv4 prefix has an invalid length: %d bits", bit_length );
@@ -831,11 +836,14 @@ dissect_lsp_ext_ip_reachability_clv(tvbuff_t *tvb, packet_info* pinfo, proto_tre
         subtree = proto_tree_add_subtree(tree, tvb, offset, 5+byte_length+subclvs_len,
                             ett_isis_lsp_part_of_clv_ext_ip_reachability, NULL, "Ext. IP Reachability");
 
-        set_address(&prefix_addr, AT_IPv4, 4, prefix);
-        proto_tree_add_ipv4_format_value(subtree, hf_isis_lsp_ext_ip_reachability_ipv4_prefix, tvb, offset+5, byte_length,
-                             tvb_get_ntohl(tvb, offset+5), "%s/%u", address_to_str(wmem_packet_scope(), &prefix_addr), bit_length);
+        set_address(&prefix_addr, AT_IPv4, 4, prefix.addr_bytes);
+
         proto_tree_add_item(subtree, hf_isis_lsp_ext_ip_reachability_metric, tvb, offset, 4, ENC_BIG_ENDIAN);
         proto_tree_add_item(subtree, hf_isis_lsp_ext_ip_reachability_distribution, tvb, offset+4, 1, ENC_NA);
+        proto_tree_add_item(subtree, hf_isis_lsp_ext_ip_reachability_subtlv, tvb, offset+4, 1, ENC_NA);
+        proto_tree_add_item(subtree, hf_isis_lsp_ext_ip_reachability_prefix_length, tvb, offset+4, 1, ENC_NA);
+
+        proto_tree_add_ipv4(subtree, hf_isis_lsp_ext_ip_reachability_ipv4_prefix, tvb, offset + 5, byte_length, prefix.addr);
 
         len = 5 + byte_length;
         if ((ctrl_info & 0x40) != 0) {
@@ -863,7 +871,7 @@ dissect_lsp_ext_ip_reachability_clv(tvbuff_t *tvb, packet_info* pinfo, proto_tre
             }
             len += 1 + subclvs_len;
         } else {
-            proto_tree_add_uint_format(subtree, hf_isis_lsp_ext_ip_reachability_subclvs_len, tvb, offset, len, 0, "no sub-TLVs present");
+            proto_tree_add_uint_format(subtree, hf_isis_lsp_ext_ip_reachability_subclvs_len, tvb, offset+len, 0, 0, "no sub-TLVs present");
         }
 
         offset += len;
@@ -4154,6 +4162,16 @@ proto_register_isis_lsp(void)
               FT_BOOLEAN, 8, TFS(&tfs_up_down), 0x80,
               NULL, HFILL }
         },
+        { &hf_isis_lsp_ext_ip_reachability_subtlv,
+            { "Sub-TLV", "isis.lsp.ext_ip_reachability.subtlv",
+              FT_BOOLEAN, 8, TFS(&tfs_yes_no), 0x40,
+              NULL, HFILL }
+        },
+        { &hf_isis_lsp_ext_ip_reachability_prefix_length,
+            { "Prefix Length", "isis.lsp.ext_ip_reachability.prefix_length",
+              FT_UINT8, BASE_DEC, NULL, 0x3F,
+              NULL, HFILL }
+        },
         { &hf_isis_lsp_grp_macaddr_length,
             { "Length", "isis.lsp.grp_macaddr.length",
               FT_UINT8, BASE_DEC, NULL, 0x0,