packet-brcm-tag: Add Broadcom tag dissection

Add support for dissecting the old-style Broadcom tag with Ethertype 0x8874,
this was supported by switches like Broadcom BCM5325. Newer switches use a
different tag format (with no Ethertype) which will be supported later.

Change-Id: Iec26f8d13058399a35fb258ccadc48f7f5ac8474
Reviewed-on: https://code.wireshark.org/review/23592
Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Reviewed-by: Michael Mann <mmann78@netscape.net>

5 files changed, 209 insertions, 0 deletions

diff --git a/epan/dissectors/CMakeLists.txt b/epan/dissectors/CMakeLists.txt
index ce06e363d6..cca5b48c1a 100644
--- a/epan/dissectors/CMakeLists.txt
+++ b/epan/dissectors/CMakeLists.txt
@@ -679,6 +679,7 @@ set(DISSECTOR_SRC
 	packet-bootparams.c
 	packet-bpdu.c
 	packet-bpq.c
+	packet-brcm-tag.c
 	packet-brdwlk.c
 	packet-brp.c
 	packet-bssap.c
diff --git a/epan/dissectors/Makefile.am b/epan/dissectors/Makefile.am
index 868711aa2d..0b3e7a9be3 100644
--- a/epan/dissectors/Makefile.am
+++ b/epan/dissectors/Makefile.am
@@ -334,6 +334,7 @@ DISSECTOR_SRC = \
 	packet-bootparams.c	\
 	packet-bpdu.c		\
 	packet-bpq.c		\
+	packet-brcm-tag.c	\
 	packet-brdwlk.c		\
 	packet-brp.c		\
 	packet-bssap.c		\
diff --git a/epan/dissectors/packet-brcm-tag.c b/epan/dissectors/packet-brcm-tag.c
new file mode 100644
index 0000000000..cfef3ab2fa
--- /dev/null
+++ b/epan/dissectors/packet-brcm-tag.c
@@ -0,0 +1,202 @@
+/* packet-brcm-tag.c
+ * Routines for Broadcom tag dissection
+ *
+ * Copyright 2017, Florian Fainelli <f.fainelli[AT]gmail.com>
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald[AT]wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+
+#include <epan/packet.h>
+#include <epan/etypes.h>
+#include <epan/ptvcursor.h>
+
+void proto_register_brcm_tag(void);
+void proto_reg_handoff_brcm_tag(void);
+
+#define BRCM_TAG_LEN                    4
+#define BRCM_TAG_OPCODE_MASK            0x7
+#define BRCM_TAG_DEV_ID_MASK            0x3
+#define BRCM_TAG_SRC_DEV_ID_SHIFT       4
+#define BRCM_TAG_PORT_ID_MASK           0xF
+
+#define BRCM_TAG_OPCODE_UNICAST         0x0
+#define BRCM_TAG_OPCODE_MULTICAST       0x1
+#define BRCM_TAG_OPCODE_EG_DIRECT       0x2
+#define BRCM_TAG_OPCODE_IG_DIRECT       0x3
+#define BRCM_TAG_OPCODE_SHIFT           5
+
+#define BRCM_TAG_MR_SHIFT               4
+#define BRCM_TAG_MO_SHIFT               3
+
+static int proto_brcm_tag               = -1;
+
+static int hf_brcm_tag_opcode           = -1;
+static int hf_brcm_tag_frame_octet_cnt  = -1;
+static int hf_brcm_tag_mr               = -1;
+static int hf_brcm_tag_mo               = -1;
+static int hf_brcm_tag_reserved         = -1;
+static int hf_brcm_tag_dest_dev_id      = -1;
+static int hf_brcm_tag_dest_port_id     = -1;
+static int hf_brcm_tag_src_dev_id       = -1;
+static int hf_brcm_tag_src_port_id      = -1;
+
+static gint ett_brcm_tag                = -1;
+
+#define TVB_LEN_GREATEST  1
+#define TVB_LEN_UNDEF     0
+#define TVB_LEN_SHORTEST -1
+
+static int check_tvb_length(ptvcursor_t *cursor, const gint length)
+{
+   if (!cursor)
+      return TVB_LEN_UNDEF;
+
+   if (tvb_reported_length_remaining(ptvcursor_tvbuff(cursor),
+            ptvcursor_current_offset(cursor)) < length)
+      return TVB_LEN_SHORTEST;
+
+   return TVB_LEN_GREATEST;
+}
+
+static const value_string brcm_tag_opcode_vals[] = {
+   { BRCM_TAG_OPCODE_UNICAST, "Unicast" },
+   { BRCM_TAG_OPCODE_MULTICAST, "Multicast" },
+   { BRCM_TAG_OPCODE_EG_DIRECT, "Egress directed" },
+   { BRCM_TAG_OPCODE_IG_DIRECT, "Ingress directed" },
+   { 0, NULL }
+};
+
+static int
+dissect_brcm_tag(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
+{
+   proto_item  *ti;
+   proto_tree  *brcm_tag_tree;
+   ptvcursor_t *cursor;
+   guint8 opcode_mr_mo;
+   guint8 opcode;
+
+   col_set_str(pinfo->cinfo, COL_PROTOCOL, "Broadcom tag");
+   col_set_str(pinfo->cinfo, COL_INFO, "MAC Management");
+
+   ti = proto_tree_add_item(tree, proto_brcm_tag, tvb, 0, -1, ENC_NA);
+   brcm_tag_tree = proto_item_add_subtree(ti, ett_brcm_tag);
+
+   cursor = ptvcursor_new(brcm_tag_tree, tvb, 0);
+
+   /* Check if we have enough data to process the header */
+   if (check_tvb_length(cursor, BRCM_TAG_LEN) != TVB_LEN_SHORTEST) {
+      opcode_mr_mo = tvb_get_guint8(ptvcursor_tvbuff(cursor), ptvcursor_current_offset(cursor));
+      opcode = (opcode_mr_mo >> BRCM_TAG_OPCODE_SHIFT) & BRCM_TAG_OPCODE_MASK;
+
+      ptvcursor_add_no_advance(cursor, hf_brcm_tag_opcode, 1, ENC_NA);
+      ptvcursor_add_no_advance(cursor, hf_brcm_tag_mr, 1, ENC_NA);
+      ptvcursor_add(cursor, hf_brcm_tag_mo, 1, ENC_NA);
+      ptvcursor_add(cursor, hf_brcm_tag_frame_octet_cnt, 2, ENC_BIG_ENDIAN);
+
+      if (opcode == BRCM_TAG_OPCODE_UNICAST || opcode == BRCM_TAG_OPCODE_EG_DIRECT)
+         ptvcursor_add(cursor, hf_brcm_tag_dest_dev_id, 1, ENC_NA);
+      else
+         ptvcursor_add(cursor, hf_brcm_tag_reserved, 1, ENC_NA);
+      ptvcursor_add_no_advance(cursor, hf_brcm_tag_src_dev_id, 1, ENC_NA);
+      if (opcode == BRCM_TAG_OPCODE_EG_DIRECT)
+         ptvcursor_add_no_advance(cursor, hf_brcm_tag_dest_port_id, 1, ENC_NA);
+      else
+         ptvcursor_add_no_advance(cursor, hf_brcm_tag_src_port_id, 1, ENC_NA);
+   }
+
+   ptvcursor_free(cursor);
+   return tvb_captured_length(tvb);
+}
+
+void
+proto_register_brcm_tag(void)
+{
+   static hf_register_info hf[] = {
+      { &hf_brcm_tag_opcode,
+         { "Opcode", "brcm_tag.opcode",
+            FT_UINT8, BASE_HEX, VALS(brcm_tag_opcode_vals),
+            BRCM_TAG_OPCODE_MASK << BRCM_TAG_OPCODE_SHIFT, NULL, HFILL }
+      },
+      { &hf_brcm_tag_mr,
+         { "Mirror bit", "brcm_tag.mr",
+            FT_UINT8, BASE_HEX, NULL, 1 << BRCM_TAG_MR_SHIFT, NULL, HFILL }
+      },
+      { &hf_brcm_tag_mo,
+         { "Mirror only", "brcm_tag.mo",
+            FT_UINT8, BASE_HEX, NULL, 1 << BRCM_TAG_MO_SHIFT, NULL, HFILL }
+      },
+      { &hf_brcm_tag_reserved,
+         { "Reserved", "brcm_tag.reserved",
+            FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }
+      },
+      { &hf_brcm_tag_frame_octet_cnt,
+         { "Frame octet count", "brcm_tag.frame_octet_cnt",
+            FT_UINT16, BASE_DEC, NULL, 0xFFF, NULL, HFILL }
+      },
+      { &hf_brcm_tag_dest_dev_id,
+         { "Destination device ID", "brcm_tag.dest_dev_id",
+            FT_UINT8, BASE_DEC, NULL, BRCM_TAG_DEV_ID_MASK, NULL, HFILL }
+      },
+      { &hf_brcm_tag_dest_port_id,
+         { "Destination port ID", "brcm_tag.dest_port_id",
+            FT_UINT8, BASE_DEC, NULL, BRCM_TAG_PORT_ID_MASK, NULL, HFILL }
+      },
+      { &hf_brcm_tag_src_dev_id,
+         { "Source device ID", "brcm_tag.src_dev_id",
+            FT_UINT8, BASE_DEC, NULL, BRCM_TAG_DEV_ID_MASK << BRCM_TAG_SRC_DEV_ID_SHIFT, NULL, HFILL }
+      },
+      { &hf_brcm_tag_src_port_id,
+         { "Source port ID", "brcm_tag.src_port_id",
+            FT_UINT8, BASE_DEC, NULL, BRCM_TAG_PORT_ID_MASK, NULL, HFILL }
+      },
+   };
+
+   static gint *ett[] = {
+      &ett_brcm_tag,
+   };
+   proto_brcm_tag = proto_register_protocol("Broadcom tag protocol", "Broadcom tag", "brcm-tag");
+
+   proto_register_field_array(proto_brcm_tag, hf, array_length(hf));
+
+   proto_register_subtree_array(ett, array_length(ett));
+}
+
+void
+proto_reg_handoff_brcm_tag(void)
+{
+   dissector_handle_t brcm_tag_handle;
+
+   brcm_tag_handle = create_dissector_handle(dissect_brcm_tag, proto_brcm_tag);
+   dissector_add_uint("ethertype", ETHERTYPE_BRCM_TYPE, brcm_tag_handle);
+}
+
+/*
+ * Editor modelines
+ *
+ * Local Variables:
+ * c-basic-offset: 3
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * ex: set shiftwidth=3 tabstop=8 expandtab:
+ * :indentSize=3:tabSize=8:noTabs=true:
+ */
diff --git a/epan/dissectors/packet-ethertype.c b/epan/dissectors/packet-ethertype.c
index feb42b4e5b..8769af55ca 100644
--- a/epan/dissectors/packet-ethertype.c
+++ b/epan/dissectors/packet-ethertype.c
@@ -82,6 +82,7 @@ const value_string etype_vals[] = {
 	{ ETHERTYPE_INTEL_ANS,            "Intel ANS probe" },
 	{ ETHERTYPE_MS_NLB_HEARTBEAT,     "MS NLB heartbeat" },
 	{ ETHERTYPE_JUMBO_LLC,            "Jumbo LLC" },
+	{ ETHERTYPE_BRCM_TYPE,            "Broadcom tag" },
 	{ ETHERTYPE_HOMEPLUG,             "Homeplug" },
 	{ ETHERTYPE_HOMEPLUG_AV,          "Homeplug AV" },
 	{ ETHERTYPE_MRP,                  "MRP" },
diff --git a/epan/etypes.h b/epan/etypes.h
index bbe32aef23..4ec6736d9a 100644
--- a/epan/etypes.h
+++ b/epan/etypes.h
@@ -324,6 +324,10 @@ extern "C" {
 #define ETHERTYPE_JUMBO_LLC		0x8870	/* 802.2 jumbo frames http://tools.ietf.org/html/draft-ietf-isis-ext-eth */
 #endif
 
+#ifndef ETHERTYPE_BRCM_TYPE
+#define ETHERTYPE_BRCM_TYPE		0x8874	/* Broadcom Ethernet switches management tag */
+#endif
+
 #ifndef ETHERTYPE_HOMEPLUG
 #define ETHERTYPE_HOMEPLUG		0x887B	/* IEEE assigned Ethertype */
 #endif