epan/dissectors/packet-brcm-tag.c

   1 /* packet-brcm-tag.c
   2  * Routines for Broadcom tag dissection
   3  *
   4  * Copyright 2017, Florian Fainelli <f.fainelli[AT]gmail.com>
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald[AT]wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  */
  12
  13 #include "config.h"
  14
  15 #include <epan/packet.h>
  16 #include <epan/etypes.h>
  17 #include <epan/ptvcursor.h>
  18
  19 void proto_register_brcm_tag(void);
  20 void proto_reg_handoff_brcm_tag(void);
  21
  22 static dissector_handle_t brcm_tag_handle;
  23
  24 #define BRCM_TAG_LEN                    4
  25 #define BRCM_TAG_OPCODE_MASK            0x7
  26 #define BRCM_TAG_DEV_ID_MASK            0x3
  27 #define BRCM_TAG_SRC_DEV_ID_SHIFT       4
  28 #define BRCM_TAG_PORT_ID_MASK           0xF
  29
  30 #define BRCM_TAG_OPCODE_UNICAST         0x0
  31 #define BRCM_TAG_OPCODE_MULTICAST       0x1
  32 #define BRCM_TAG_OPCODE_EG_DIRECT       0x2
  33 #define BRCM_TAG_OPCODE_IG_DIRECT       0x3
  34 #define BRCM_TAG_OPCODE_SHIFT           5
  35
  36 #define BRCM_TAG_MR_SHIFT               4
  37 #define BRCM_TAG_MO_SHIFT               3
  38
  39 static int proto_brcm_tag;
  40
  41 static int hf_brcm_tag_opcode;
  42 static int hf_brcm_tag_frame_octet_cnt;
  43 static int hf_brcm_tag_mr;
  44 static int hf_brcm_tag_mo;
  45 static int hf_brcm_tag_reserved;
  46 static int hf_brcm_tag_dest_dev_id;
  47 static int hf_brcm_tag_dest_port_id;
  48 static int hf_brcm_tag_src_dev_id;
  49 static int hf_brcm_tag_src_port_id;
  50
  51 static int ett_brcm_tag;
  52
  53 #define TVB_LEN_GREATEST  1
  54 #define TVB_LEN_UNDEF     0
  55 #define TVB_LEN_SHORTEST -1
  56
  57 static int check_tvb_length(ptvcursor_t *cursor, const int length)
  58 {
  59    if (!cursor)
  60       return TVB_LEN_UNDEF;
  61
  62    if (tvb_reported_length_remaining(ptvcursor_tvbuff(cursor),
  63             ptvcursor_current_offset(cursor)) < length)
  64       return TVB_LEN_SHORTEST;
  65
  66    return TVB_LEN_GREATEST;
  67 }
  68
  69 static const value_string brcm_tag_opcode_vals[] = {
  70    { BRCM_TAG_OPCODE_UNICAST, "Unicast" },
  71    { BRCM_TAG_OPCODE_MULTICAST, "Multicast" },
  72    { BRCM_TAG_OPCODE_EG_DIRECT, "Egress directed" },
  73    { BRCM_TAG_OPCODE_IG_DIRECT, "Ingress directed" },
  74    { 0, NULL }
  75 };
  76
  77 static int
  78 dissect_brcm_tag(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  79 {
  80    proto_item  *ti;
  81    proto_tree  *brcm_tag_tree;
  82    ptvcursor_t *cursor;
  83    uint8_t opcode_mr_mo;
  84    uint8_t opcode;
  85
  86    col_set_str(pinfo->cinfo, COL_PROTOCOL, "Broadcom tag");
  87    col_set_str(pinfo->cinfo, COL_INFO, "MAC Management");
  88
  89    ti = proto_tree_add_item(tree, proto_brcm_tag, tvb, 0, -1, ENC_NA);
  90    brcm_tag_tree = proto_item_add_subtree(ti, ett_brcm_tag);
  91
  92    cursor = ptvcursor_new(pinfo->pool, brcm_tag_tree, tvb, 0);
  93
  94    /* Check if we have enough data to process the header */
  95    if (check_tvb_length(cursor, BRCM_TAG_LEN) != TVB_LEN_SHORTEST) {
  96       opcode_mr_mo = tvb_get_uint8(ptvcursor_tvbuff(cursor), ptvcursor_current_offset(cursor));
  97       opcode = (opcode_mr_mo >> BRCM_TAG_OPCODE_SHIFT) & BRCM_TAG_OPCODE_MASK;
  98
  99       ptvcursor_add_no_advance(cursor, hf_brcm_tag_opcode, 1, ENC_NA);
 100       ptvcursor_add_no_advance(cursor, hf_brcm_tag_mr, 1, ENC_NA);
 101       ptvcursor_add(cursor, hf_brcm_tag_mo, 1, ENC_NA);
 102       ptvcursor_add(cursor, hf_brcm_tag_frame_octet_cnt, 2, ENC_BIG_ENDIAN);
 103
 104       if (opcode == BRCM_TAG_OPCODE_UNICAST || opcode == BRCM_TAG_OPCODE_EG_DIRECT)
 105          ptvcursor_add(cursor, hf_brcm_tag_dest_dev_id, 1, ENC_NA);
 106       else
 107          ptvcursor_add(cursor, hf_brcm_tag_reserved, 1, ENC_NA);
 108       ptvcursor_add_no_advance(cursor, hf_brcm_tag_src_dev_id, 1, ENC_NA);
 109       if (opcode == BRCM_TAG_OPCODE_EG_DIRECT)
 110          ptvcursor_add_no_advance(cursor, hf_brcm_tag_dest_port_id, 1, ENC_NA);
 111       else
 112          ptvcursor_add_no_advance(cursor, hf_brcm_tag_src_port_id, 1, ENC_NA);
 113    }
 114
 115    ptvcursor_free(cursor);
 116    return tvb_captured_length(tvb);
 117 }
 118
 119 void
 120 proto_register_brcm_tag(void)
 121 {
 122    static hf_register_info hf[] = {
 123       { &hf_brcm_tag_opcode,
 124          { "Opcode", "brcm_tag.opcode",
 125             FT_UINT8, BASE_HEX, VALS(brcm_tag_opcode_vals),
 126             BRCM_TAG_OPCODE_MASK << BRCM_TAG_OPCODE_SHIFT, NULL, HFILL }
 127       },
 128       { &hf_brcm_tag_mr,
 129          { "Mirror bit", "brcm_tag.mr",
 130             FT_UINT8, BASE_HEX, NULL, 1 << BRCM_TAG_MR_SHIFT, NULL, HFILL }
 131       },
 132       { &hf_brcm_tag_mo,
 133          { "Mirror only", "brcm_tag.mo",
 134             FT_UINT8, BASE_HEX, NULL, 1 << BRCM_TAG_MO_SHIFT, NULL, HFILL }
 135       },
 136       { &hf_brcm_tag_reserved,
 137          { "Reserved", "brcm_tag.reserved",
 138             FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }
 139       },
 140       { &hf_brcm_tag_frame_octet_cnt,
 141          { "Frame octet count", "brcm_tag.frame_octet_cnt",
 142             FT_UINT16, BASE_DEC, NULL, 0x0FFF, NULL, HFILL }
 143       },
 144       { &hf_brcm_tag_dest_dev_id,
 145          { "Destination device ID", "brcm_tag.dest_dev_id",
 146             FT_UINT8, BASE_DEC, NULL, BRCM_TAG_DEV_ID_MASK, NULL, HFILL }
 147       },
 148       { &hf_brcm_tag_dest_port_id,
 149          { "Destination port ID", "brcm_tag.dest_port_id",
 150             FT_UINT8, BASE_DEC, NULL, BRCM_TAG_PORT_ID_MASK, NULL, HFILL }
 151       },
 152       { &hf_brcm_tag_src_dev_id,
 153          { "Source device ID", "brcm_tag.src_dev_id",
 154             FT_UINT8, BASE_DEC, NULL, BRCM_TAG_DEV_ID_MASK << BRCM_TAG_SRC_DEV_ID_SHIFT, NULL, HFILL }
 155       },
 156       { &hf_brcm_tag_src_port_id,
 157          { "Source port ID", "brcm_tag.src_port_id",
 158             FT_UINT8, BASE_DEC, NULL, BRCM_TAG_PORT_ID_MASK, NULL, HFILL }
 159       },
 160    };
 161
 162    static int *ett[] = {
 163       &ett_brcm_tag,
 164    };
 165    proto_brcm_tag = proto_register_protocol("Broadcom tag protocol", "Broadcom tag", "brcm-tag");
 166
 167    proto_register_field_array(proto_brcm_tag, hf, array_length(hf));
 168
 169    proto_register_subtree_array(ett, array_length(ett));
 170
 171    brcm_tag_handle = register_dissector("brcm-tag", dissect_brcm_tag, proto_brcm_tag);
 172 }
 173
 174 void
 175 proto_reg_handoff_brcm_tag(void)
 176 {
 177    dissector_add_uint("ethertype", ETHERTYPE_BRCM_TYPE, brcm_tag_handle);
 178 }
 179
 180 /*
 181  * Editor modelines
 182  *
 183  * Local Variables:
 184  * c-basic-offset: 3
 185  * tab-width: 8
 186  * indent-tabs-mode: nil
 187  * End:
 188  *
 189  * ex: set shiftwidth=3 tabstop=8 expandtab:
 190  * :indentSize=3:tabSize=8:noTabs=true:
 191  */