path: root/epan/dissectors/packet-amr.c

/* packet-amr.c
 * Routines for AMR dissection
 * Copyright 2005-2008, Anders Broman <anders.broman[at]ericsson.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * References:
 * RFC 3267  https://tools.ietf.org/html/rfc3267
 * RFC 4867  https://tools.ietf.org/html/rfc4867
 * 3GPP TS 26.101 for AMR-NB, 3GPP TS 26.201 for AMR-WB
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/oids.h>
#include <epan/asn1.h>
#include <epan/tfs.h>

#include "packet-rtp.h"

void proto_register_amr(void);
void proto_reg_handoff_amr(void);

#define AMR_NB_SID 8
#define AMR_WB_SID 9
#define AMR_NO_TRANS 15

#define AMR_NB 0
#define AMR_WB 1

#define AMR_OA 0
#define AMR_BE 1
#define AMR_IF1 2
#define AMR_IF2 3

static dissector_handle_t amr_handle;
static dissector_handle_t amr_wb_handle;

/* Initialize the protocol and registered fields */
static int proto_amr;
static int proto_amr_wb;
static int hf_amr_nb_cmr;
static int hf_amr_wb_cmr;
static int hf_amr_payload_decoded_as;
static int hf_amr_reserved;
static int hf_amr_toc_f;
static int hf_amr_nb_toc_ft;
static int hf_amr_wb_toc_ft;
static int hf_amr_toc_q;

static int hf_amr_speech_data;
static int hf_amr_frame_data;
static int hf_amr_nb_if1_ft;
static int hf_amr_wb_if1_ft;
static int hf_amr_if1_fqi;
static int hf_amr_nb_if1_mode_req;
static int hf_amr_wb_if1_mode_req;
static int hf_amr_if1_sti;
static int hf_amr_nb_if1_mode_ind;
static int hf_amr_wb_if1_mode_ind;
static int hf_amr_nb_if1_sti_mode_ind;
static int hf_amr_wb_if1_sti_mode_ind;
static int hf_amr_if2_sti;
static int hf_amr_nb_if2_sti_mode_ind;
static int hf_amr_wb_if2_sti_mode_ind;

static int hf_amr_nb_if2_ft;
static int hf_amr_wb_if2_ft;


/* Initialize the subtree pointers */
static int ett_amr;
static int ett_amr_toc;

static expert_field ei_amr_spare_bit_not0;
static expert_field ei_amr_not_enough_data_for_frames;
static expert_field ei_amr_superfluous_data;
static expert_field ei_amr_padding_bits_not0;
static expert_field ei_amr_padding_bits_correct;
static expert_field ei_amr_reserved;

static int   amr_encoding_type         = AMR_OA;
static int   pref_amr_mode             = AMR_NB;


/* Currently only octet aligned works */
/* static bool octet_aligned = true; */

static const value_string amr_encoding_type_value[] = {
    {AMR_OA, "RFC 3267"},
    {AMR_BE, "RFC 3267 bandwidth-efficient mode"},
    {AMR_IF1, "AMR IF 1"},
    {AMR_IF2, "AMR IF 2"},
    { 0,    NULL }
};


/* Table 1a of 3GPP TS 26.201*/
static const value_string amr_nb_codec_mode_vals[] = {
    {0,            "AMR 4,75 kbit/s"},
    {1,            "AMR 5,15 kbit/s"},
    {2,            "AMR 5,90 kbit/s"},
    {3,            "AMR 6,70 kbit/s (PDC-EFR)"},
    {4,            "AMR 7,40 kbit/s (TDMA-EFR)"},
    {5,            "AMR 7,95 kbit/s"},
    {6,            "AMR 10,2 kbit/s"},
    {7,            "AMR 12,2 kbit/s (GSM-EFR)"},
    {AMR_NB_SID,   "AMR SID (Comfort Noise Frame)"},
    {9,            "GSM-EFR SID"},
    {10,           "TDMA-EFR SID "},
    {11,           "PDC-EFR SID"},
    {12,           "Illegal Frametype - for future use"},
    {13,           "Illegal Frametype - for future use"},
    {14,           "Illegal Frametype - for future use"},
    {AMR_NO_TRANS, "No Data (No transmission/No reception)"},
    { 0,    NULL }
};
static value_string_ext amr_nb_codec_mode_vals_ext = VALUE_STRING_EXT_INIT(amr_nb_codec_mode_vals);

static const value_string amr_wb_codec_mode_vals[] = {
    {0,            "AMR-WB 6.60 kbit/s"},
    {1,            "AMR-WB 8.85 kbit/s"},
    {2,            "AMR-WB 12.65 kbit/s"},
    {3,            "AMR-WB 14.25 kbit/s"},
    {4,            "AMR-WB 15.85 kbit/s"},
    {5,            "AMR-WB 18.25 kbit/s"},
    {6,            "AMR-WB 19.85 kbit/s"},
    {7,            "AMR-WB 23.05 kbit/s"},
    {8,            "AMR-WB 23.85 kbit/s"},
    {AMR_WB_SID,   "AMR-WB SID (Comfort Noise Frame)"},
    {10,           "Illegal Frametype"},
    {11,           "Illegal Frametype"},
    {12,           "Illegal Frametype"},
    {13,           "Illegal Frametype"},
    {14,           "Speech lost"},
    {AMR_NO_TRANS, "No Data (No transmission/No reception)"},
    { 0,    NULL }
};

static value_string_ext amr_wb_codec_mode_vals_ext = VALUE_STRING_EXT_INIT(amr_wb_codec_mode_vals);

/* Ref 3GPP TS 26.101 table 1a for AMR-NB*/

/* From RFC3267 chapter 4.3.1
CMR (4 bits): Indicates a codec mode request sent to the speech
      encoder at the site of the receiver of this payload.  The value of
      the CMR field is set to the frame type index of the corresponding
      speech mode being requested.  The frame type index may be 0-7 for
      AMR, as defined in Table 1a in [2], or 0-8 for AMR-WB, as defined
      in Table 1a in [3GPP TS 26.201].  CMR value 15 indicates that no
      mode request is present, and other values are for future use.
*/
static const value_string amr_nb_codec_mode_request_vals[] = {
    {0,  "AMR 4,75 kbit/s"},
    {1,  "AMR 5,15 kbit/s"},
    {2,  "AMR 5,90 kbit/s"},
    {3,  "AMR 6,70 kbit/s (PDC-EFR)"},
    {4,  "AMR 7,40 kbit/s (TDMA-EFR)"},
    {5,  "AMR 7,95 kbit/s"},
    {6,  "AMR 10,2 kbit/s"},
    {7,  "AMR 12,2 kbit/s (GSM-EFR)"},
    {8,  "Illegal Frametype - For future use"},
    {9,  "Illegal Frametype - For future use"},
    {10, "Illegal Frametype - For future use"},
    {11, "Illegal Frametype - For future use"},
    {12, "Illegal Frametype - For future use"},
    {13, "Illegal Frametype - For future use"},
    {14, "Illegal Frametype - For future use"},
    {15, "No mode request"},
    { 0,    NULL }
};
static value_string_ext amr_nb_codec_mode_request_vals_ext = VALUE_STRING_EXT_INIT(amr_nb_codec_mode_request_vals);

/* Ref 3GPP TS 26.201 table 1a for AMR-WB*/
static const value_string amr_wb_codec_mode_request_vals[] = {
    {0,  "AMR-WB 6.60 kbit/s"},
    {1,  "AMR-WB 8.85 kbit/s"},
    {2,  "AMR-WB 12.65 kbit/s"},
    {3,  "AMR-WB 14.25 kbit/s"},
    {4,  "AMR-WB 15.85 kbit/s"},
    {5,  "AMR-WB 18.25 kbit/s"},
    {6,  "AMR-WB 19.85 kbit/s"},
    {7,  "AMR-WB 23.05 kbit/s"},
    {8,  "AMR-WB 23.85 kbit/s"},
    {9,  "Illegal Frametype - For future use"},
    {10, "Illegal Frametype - For future use"},
    {11, "Illegal Frametype - For future use"},
    {12, "Illegal Frametype - For future use"},
    {13, "Illegal Frametype - For future use"},
    {14, "Illegal Frametype - For future use"},
    {15, "No mode request"},
    { 0,    NULL }
};
static value_string_ext amr_wb_codec_mode_request_vals_ext = VALUE_STRING_EXT_INIT(amr_wb_codec_mode_request_vals);

static const true_false_string toc_f_bit_vals = {
    "Followed by another speech frame",
    "Last frame in this payload"
};

static const true_false_string toc_q_bit_vals = {
    "Ok",
    "Severely damaged frame"
};

static const true_false_string amr_sti_vals = {
    "SID_UPDATE",
    "SID_FIRST"
};

static wmem_map_t *amr_default_fmtp;

static void
amr_apply_prefs(void) {
    wmem_map_insert(amr_default_fmtp, "octet-align", (amr_encoding_type == AMR_OA) ? "1" : "0");
}

/* See 3GPP TS 26.101 chapter 4 for AMR-NB IF1 */
static int
dissect_amr_nb_if1(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) {
    int         offset = 0;
    uint8_t     octet;
    proto_item *ti;

    proto_tree_add_item(tree, hf_amr_nb_if1_ft, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_amr_if1_fqi,   tvb, offset, 1, ENC_BIG_ENDIAN);
    octet = (tvb_get_uint8(tvb,offset) & 0xf0) >> 4;
    if (octet == AMR_NB_SID) {
        ti = proto_tree_add_item(tree, hf_amr_nb_if1_mode_req, tvb, offset+1, 1, ENC_BIG_ENDIAN);
        if (tvb_get_uint8(tvb,offset+1) & 0x1f)
            expert_add_info(pinfo, ti, &ei_amr_spare_bit_not0);
        proto_tree_add_item(tree, hf_amr_speech_data, tvb, offset+2, 5, ENC_NA);
        proto_tree_add_item(tree, hf_amr_if1_sti, tvb, offset+7, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_amr_nb_if1_sti_mode_ind, tvb, offset+7, 1, ENC_BIG_ENDIAN);
        return offset+8;
    }

    proto_tree_add_item(tree, hf_amr_nb_if1_mode_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    ti = proto_tree_add_item(tree, hf_amr_nb_if1_mode_req, tvb, offset, 1, ENC_BIG_ENDIAN);
    if (tvb_get_uint8(tvb,offset) & 0x1f)
        expert_add_info(pinfo, ti, &ei_amr_spare_bit_not0);
    offset += 1;
    proto_tree_add_item(tree, hf_amr_speech_data, tvb, offset, -1, ENC_NA);
    return tvb_captured_length(tvb);
}

/* See 3GPP TS 26.201 for AMR-WB */
static int
dissect_amr_wb_if1(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) {
    int         offset = 0;
    uint8_t     octet;
    proto_item *ti;

    proto_tree_add_item(tree, hf_amr_wb_if1_ft, tvb, offset, 1, ENC_BIG_ENDIAN);
    ti = proto_tree_add_item(tree, hf_amr_if1_fqi, tvb, offset, 1, ENC_BIG_ENDIAN);
    if (tvb_get_uint8(tvb,offset) & 0x03)
        expert_add_info(pinfo, ti, &ei_amr_spare_bit_not0);
    octet = (tvb_get_uint8(tvb,offset) & 0xf0) >> 4;
    if (octet == AMR_WB_SID) {
        proto_tree_add_item(tree, hf_amr_wb_if1_mode_req, tvb, offset+1, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_amr_speech_data, tvb, offset+2, 4, ENC_NA);
        proto_tree_add_item(tree, hf_amr_if1_sti, tvb, offset+7, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_amr_wb_if1_sti_mode_ind, tvb, offset+7, 1, ENC_BIG_ENDIAN);
        return offset+8;
    }

    offset += 1;
    proto_tree_add_item(tree, hf_amr_wb_if1_mode_ind, tvb, offset, 1, ENC_BIG_ENDIAN);
    proto_tree_add_item(tree, hf_amr_wb_if1_mode_req, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset += 1;
    proto_tree_add_item(tree, hf_amr_speech_data, tvb, offset, -1, ENC_NA);
    return tvb_captured_length(tvb);
}

static int
dissect_amr_nb_if2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) {
    int    offset = 0;
    uint8_t octet;

    proto_tree_add_item(tree, hf_amr_nb_if2_ft, tvb, offset, 1, ENC_BIG_ENDIAN);
    octet = tvb_get_uint8(tvb,offset) & 0x0f;

    if (octet == AMR_NB_SID) {
        proto_tree_add_item(tree, hf_amr_speech_data, tvb, offset+1, 3, ENC_NA);
        proto_tree_add_item(tree, hf_amr_if2_sti, tvb, offset+4, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_amr_nb_if2_sti_mode_ind, tvb, offset+5, 1, ENC_BIG_ENDIAN);
        return offset+6;
    }
    if (octet == AMR_NO_TRANS)
        return 1;
    proto_tree_add_item(tree, hf_amr_speech_data, tvb, offset+1, -1, ENC_NA);

    col_append_fstr(pinfo->cinfo, COL_INFO, "%s ",
            val_to_str_ext(octet, &amr_nb_codec_mode_request_vals_ext, "Unknown (%d)" ));
    return tvb_captured_length(tvb);
}

static int
dissect_amr_wb_if2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) {
    int    offset = 0;
    uint8_t octet;

    proto_tree_add_item(tree, hf_amr_wb_if2_ft, tvb, offset, 1, ENC_BIG_ENDIAN);
    octet = (tvb_get_uint8(tvb,offset) & 0xf0) >> 4;

    if (octet == AMR_WB_SID) {
        proto_tree_add_item(tree, hf_amr_speech_data, tvb, offset+1, 4, ENC_NA);
        proto_tree_add_item(tree, hf_amr_if2_sti, tvb, offset+5, 1, ENC_BIG_ENDIAN);
        proto_tree_add_item(tree, hf_amr_wb_if2_sti_mode_ind, tvb, offset+5, 1, ENC_BIG_ENDIAN);
        return offset+6;
    }
    if (octet == AMR_NO_TRANS)
        return 1;
    proto_tree_add_item(tree, hf_amr_speech_data, tvb, offset+1, -1, ENC_NA);

    col_append_fstr(pinfo->cinfo, COL_INFO, "%s ",
            val_to_str_ext(octet, &amr_wb_codec_mode_request_vals_ext, "Unknown (%d)" ));
    return tvb_captured_length(tvb);
}

static void
dissect_amr_be(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int amr_mode) {
    proto_item *item;
    int         ft;
    int         bit_offset = 0;
    int         bitcount;       /*bitcounter, MSB = bit 0, over bytes*/
    int         bits_used_for_frames = 0;
    int         bytes_needed_for_frames;
    uint8_t     f_bit, q_bit;

    /* Number of bits per frame for AMR-NB, see Table 1 RFC3267*/
    /* Values taken for GSM-EFR SID, TDMA-EFR SID and PDC-EFR SID from 3GPP 26.101 Table A.1b */

    /*               Frame type     0   1   2   3   4   5   6   7  8  9  10 11 12 13 14 15 */
    unsigned char Framebits_NB[] = {95,103,118,134,148,159,204,244,39,43,38,37, 0, 0, 0, 0};

    /* Number of bits per frame for AMR-WB, see 3GPP TS 26.201 Table 2*/
    /*               Frame type     0   1   2   3   4   5   6   7   8   9  10 11 12 13 14 15 */
    unsigned int Framebits_WB[] = {132,177,253,285,317,365,397,461,477, 40, 0, 0, 0, 0, 0, 0,};


    /* Chapter 4.3 */

    bitcount = 3;
    if (amr_mode == AMR_NB)
        proto_tree_add_bits_item(tree, hf_amr_nb_cmr, tvb, bit_offset, 4, ENC_BIG_ENDIAN);
    else
        proto_tree_add_bits_item(tree, hf_amr_wb_cmr, tvb, bit_offset, 4, ENC_BIG_ENDIAN);

    bit_offset += 4;
    /* In bandwidth-efficient mode, a ToC entry takes the following format:
     *
     *    0 1 2 3 4 5
     *   +-+-+-+-+-+-+
     *   |F|  FT   |Q|
     *   +-+-+-+-+-+-+
     *
     *   F (1 bit): If set to 1, indicates that this frame is followed by
     *      another speech frame in this payload; if set to 0, indicates that
     *      this frame is the last frame in this payload.
     *
     *   FT (4 bits): Frame type index, indicating either the AMR or AMR-WB
     *      speech coding mode or comfort noise (SID) mode of the
     *      corresponding frame carried in this payload.
     */
    do {
        /* Check F bit */
        bitcount += 1;
        f_bit = tvb_get_bits8(tvb, bit_offset, 1);
        proto_tree_add_bits_item(tree, hf_amr_toc_f, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
        bit_offset += 1;
        ft = tvb_get_bits8(tvb, bit_offset, 4);
        if (amr_mode == AMR_NB)
            item = proto_tree_add_bits_item(tree, hf_amr_nb_toc_ft, tvb, bit_offset, 4, ENC_BIG_ENDIAN);
        else
            item = proto_tree_add_bits_item(tree, hf_amr_wb_toc_ft, tvb, bit_offset, 4, ENC_BIG_ENDIAN);

        bit_offset += 4;
        bitcount   += 4;
        if (amr_mode == AMR_NB)
            bits_used_for_frames += Framebits_NB[ft];
        else
            bits_used_for_frames += Framebits_WB[ft];
        /* Check Q bit */
        q_bit = tvb_get_bits8(tvb, bit_offset, 1);
        proto_tree_add_bits_item(tree, hf_amr_toc_q, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
        bit_offset += 1;
        bitcount   += 1;
        if (q_bit == 1)
            proto_item_append_text(item, " / Frame OK");
        else
            proto_item_append_text(item, " / Frame damaged");
    } while ((f_bit == 1) && (tvb_reported_length_remaining(tvb, bitcount/8) > 2));

    if (bits_used_for_frames > 0)
        bytes_needed_for_frames = 1 + (bitcount+bits_used_for_frames)/8-bitcount/8;
    else
        bytes_needed_for_frames = 0;

    /* Check if we have enough data available for our frames */
    if (tvb_reported_length_remaining(tvb, bitcount/8) < bytes_needed_for_frames) {
        proto_tree_add_expert_format(tree, pinfo, &ei_amr_not_enough_data_for_frames,
                tvb, bitcount/8, bytes_needed_for_frames,
                "Error: %d Bytes available, %d would be needed!",
                       tvb_reported_length_remaining(tvb, bitcount/8),
                       bytes_needed_for_frames);
    }
    else {
        proto_tree_add_item(tree, hf_amr_frame_data, tvb, bitcount/8, bytes_needed_for_frames, ENC_NA);
    }

    bitcount += bits_used_for_frames;

    if (tvb_reported_length_remaining(tvb, (bitcount+8)/8) > 0) {
        proto_tree_add_expert_format(tree, pinfo, &ei_amr_superfluous_data, tvb, bitcount/8, tvb_reported_length_remaining(tvb, bitcount/8),
            "Error: %d Bytes remaining - should be 0!",tvb_reported_length_remaining(tvb, (bitcount+8)/8));

        /* Now check the paddings */
        if (bitcount%8 != 0) {
            if ( (1 << (8 -(bitcount%8)-1)) & tvb_get_uint8(tvb,bitcount/8) )
                proto_tree_add_expert(tree, pinfo, &ei_amr_padding_bits_correct, tvb, bitcount/8, 1);
            else {
                proto_tree_add_expert(tree, pinfo, &ei_amr_padding_bits_not0, tvb,
                                        bitcount/8, 1);
            }
        }
    }
}

/* Code to actually dissect the packets */
static void
dissect_amr_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int amr_mode, unsigned encoding)
{
    int         offset     = 0;
    int         bit_offset = 0;
    uint8_t     octet;
    proto_item *item;
    bool        first_time;

/* Set up structures needed to add the protocol subtree and manage it */
    proto_item *ti;
    proto_tree *amr_tree, *toc_tree;

    ti = proto_tree_add_item(tree, proto_amr, tvb, 0, -1, ENC_NA);
    amr_tree = proto_item_add_subtree(ti, ett_amr);

    item = proto_tree_add_uint(amr_tree, hf_amr_payload_decoded_as, tvb, offset, 4, encoding);
    proto_item_set_len(item, tvb_reported_length(tvb));
    proto_item_set_generated(item);

    switch (encoding) {
    case AMR_OA: /* RFC 3267 Octet aligned */
        break;
    case AMR_BE: /* RFC 3267 Bandwidth-efficient */
        dissect_amr_be(tvb, pinfo, amr_tree, amr_mode);
        return;
    case AMR_IF1:
        if (amr_mode == AMR_NB)
            dissect_amr_nb_if1(tvb, pinfo, amr_tree, NULL);
        else
            dissect_amr_wb_if1(tvb, pinfo, amr_tree, NULL);
        return;
    case AMR_IF2:
        if (amr_mode == AMR_NB)
            dissect_amr_nb_if2(tvb, pinfo, amr_tree, NULL);
        else
            dissect_amr_wb_if2(tvb, pinfo, amr_tree, NULL);
        return;
    default:
        break;
    }

    octet = tvb_get_uint8(tvb,offset) & 0x0f;
    if ( octet != 0  ) {
        item = proto_tree_add_item(amr_tree, hf_amr_reserved, tvb, offset, 1, ENC_BIG_ENDIAN);
        expert_add_info(pinfo, item, &ei_amr_reserved);
        proto_item_set_generated(item);
        dissect_amr_be(tvb, pinfo, amr_tree, amr_mode);
        return;
    }

    if (amr_mode == AMR_NB)
        proto_tree_add_bits_item(amr_tree, hf_amr_nb_cmr, tvb, bit_offset, 4, ENC_BIG_ENDIAN);
    else
        proto_tree_add_bits_item(amr_tree, hf_amr_wb_cmr, tvb, bit_offset, 4, ENC_BIG_ENDIAN);

    bit_offset += 4;
    proto_tree_add_item(amr_tree, hf_amr_reserved, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset     += 1;
    bit_offset += 4;
    /*
     *  A ToC entry takes the following format in octet-aligned mode:
     *
     *    0 1 2 3 4 5 6 7
     *   +-+-+-+-+-+-+-+-+
     *   |F|  FT   |Q|P|P|
     *   +-+-+-+-+-+-+-+-+
     *
     *   F (1 bit): see definition in Section 4.3.2.
     *
     *   FT (4 bits unsigned integer): see definition in Section 4.3.2.
     *
     *   Q (1 bit): see definition in Section 4.3.2.
     *
     *   P bits: padding bits, MUST be set to zero.
     */
    octet = tvb_get_uint8(tvb,offset);
    toc_tree = proto_tree_add_subtree(amr_tree, tvb, offset, -1, ett_amr_toc, NULL, "Payload Table of Contents");

    first_time = true;
    while ((( octet& 0x80 ) == 0x80) || (first_time == true)) {
        first_time = false;
        octet = tvb_get_uint8(tvb,offset);

        proto_tree_add_bits_item(toc_tree, hf_amr_toc_f, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
        bit_offset += 1;
        if (amr_mode == AMR_NB)
            proto_tree_add_bits_item(toc_tree, hf_amr_nb_toc_ft, tvb, bit_offset, 4, ENC_BIG_ENDIAN);
        else
            proto_tree_add_bits_item(toc_tree, hf_amr_wb_toc_ft, tvb, bit_offset, 4, ENC_BIG_ENDIAN);
        bit_offset += 4;
        proto_tree_add_bits_item(toc_tree, hf_amr_toc_q, tvb, bit_offset, 1, ENC_BIG_ENDIAN);
        bit_offset += 1;
        /* 2 padding bits */
        bit_offset += 2;
        offset     += 1;
    }

}

/* Code to actually dissect the packets */
static int
dissect_amr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
{
    struct _rtp_info *rtp_info = NULL;
    unsigned encoding = amr_encoding_type;

    if (data) {
        rtp_info = (struct _rtp_info*)data;
        if (rtp_info->info_payload_fmtp_map) {
            /* If the map is non-NULL, then the RTP conversation was set up by
             * a SDP (even if the fmtp attribute was not present, in which case
             * the map is empty.) According to RFC 4867, if octet-align is
             * "0 or if not present, bandwidth-efficient operation is employed."
             */
            char *octet_aligned = wmem_map_lookup(rtp_info->info_payload_fmtp_map, "octet-align");
            if (g_strcmp0(octet_aligned, "1") == 0) {
                encoding = AMR_OA;
            } else {
                encoding = AMR_BE;
            }
        } else {
            /* If the map is NULL, then we were called by RTP, but the RTP
             * conversation was set by Decode As or similar, and we should
             * use the preference settings.
             */
            rtp_info->info_payload_fmtp_map = amr_default_fmtp;
        }
    }

/* Make entries in Protocol column and Info column on summary display */
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "AMR");

    dissect_amr_common(tvb, pinfo, tree, pref_amr_mode, encoding);
    return tvb_captured_length(tvb);
}

static int
dissect_amr_wb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    struct _rtp_info *rtp_info = NULL;
    unsigned encoding = amr_encoding_type;

    if (data) {
        rtp_info = (struct _rtp_info*)data;
        if (rtp_info->info_payload_fmtp_map) {
            /* If the map is non-NULL, then the RTP conversation was set up by
             * a SDP (even if the fmtp attribute was not present, in which case
             * the map is empty.) According to RFC 4867, if octet-align is
             * "0 or if not present, bandwidth-efficient operation is employed."
             */
            char *octet_aligned = wmem_map_lookup(rtp_info->info_payload_fmtp_map, "octet-align");
            if (g_strcmp0(octet_aligned, "1") == 0) {
                encoding = AMR_OA;
            } else {
                encoding = AMR_BE;
            }
        } else {
            /* If the map is NULL, then we were called by RTP, but the RTP
             * conversation was set by Decode As or similar, and we should
             * use the preference settings.
             */
            rtp_info->info_payload_fmtp_map = amr_default_fmtp;
        }
    }

/* Make entries in Protocol column and Info column on summary display */
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "AMR-WB");

    dissect_amr_common(tvb, pinfo, tree, AMR_WB, encoding);
    return tvb_captured_length(tvb);
}


typedef struct _amr_capability_t {
    const char      *id;
    const char      *name;
    dissector_t  content_pdu;
} amr_capability_t;

static amr_capability_t amr_capability_tab[] = {
    /* ITU-T H.241 (05/2006), 8.3 H.264 capabilities */
    { "GenericCapability/0.0.8.245.1.1.1",              "H.245 - GSM AMR Capability Identifier", NULL },
    { "GenericCapability/0.0.8.245.1.1.1/collapsing/0", "maxAl-sduAudioFrames",                  NULL },
    { "GenericCapability/0.0.8.245.1.1.1/collapsing/1", "bitRate",                               NULL },
    { "GenericCapability/0.0.8.245.1.1.1/collapsing/2", "gsmAmrComfortNoise",                    NULL },
    { "GenericCapability/0.0.8.245.1.1.1/collapsing/3", "gsmEfrComfortNoise",                    NULL },
    { "GenericCapability/0.0.8.245.1.1.1/collapsing/4", "is-641ComfortNoise",                    NULL },
    { "GenericCapability/0.0.8.245.1.1.1/collapsing/5", "pdcEFRComfortNoise",                    NULL },
    /* ITU-T Rec. G.722.2/Annex F (11/2002) */
    { "GenericCapability/0.0.7.7222.1.0/collapsing/0",  "maxAl-sduFrames",                       NULL },
    { "GenericCapability/0.0.7.7222.1.0/collapsing/1",  "bitRate",                               NULL },
    { "GenericCapability/0.0.7.7222.1.0/collapsing/2",  "octetAlign",                            NULL },
    { "GenericCapability/0.0.7.7222.1.0/collapsing/3",  "modeSet",                               NULL },
    { "GenericCapability/0.0.7.7222.1.0/collapsing/4",  "modeChangePeriod",                      NULL },
    { "GenericCapability/0.0.7.7222.1.0/collapsing/5",  "modeChangeNeighbour",                   NULL },
    { "GenericCapability/0.0.7.7222.1.0/collapsing/6",  "crc",                                   NULL },
    { "GenericCapability/0.0.7.7222.1.0/collapsing/7",  "robustSorting",                         NULL },
    { "GenericCapability/0.0.7.7222.1.0/collapsing/8",  "interleaving",                          NULL },
    { NULL, NULL, NULL },
};

static amr_capability_t *find_cap(const char *id) {
    amr_capability_t *ftr = NULL;
    amr_capability_t *f;

    for (f=amr_capability_tab; f->id; f++) {
        if (!strcmp(id, f->id)) {
            ftr = f;
            break;
        }
    }
    return ftr;
}

static int
dissect_amr_name(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
{
    asn1_ctx_t *actx;

    /* Reject the packet if data is NULL */
    if (data == NULL)
        return 0;
    actx = get_asn1_ctx(data);
    DISSECTOR_ASSERT(actx != NULL);

    if (tree && (actx != NULL)) {
        amr_capability_t *ftr;
        ftr = find_cap(pinfo->match_string);
        if (ftr) {
            proto_item_append_text(actx->created_item, " - %s", ftr->name);
            proto_item_append_text(proto_item_get_parent(proto_tree_get_parent(tree)), ": %s", ftr->name);
        } else {
            proto_item_append_text(actx->created_item, " - unknown(%s)", pinfo->match_string);
        }
    }

    return tvb_reported_length(tvb);
}

void
proto_register_amr(void)
{
    module_t *amr_module;
    expert_module_t* expert_amr;

    static hf_register_info hf[] = {
        { &hf_amr_nb_cmr,
            { "CMR",           "amr.nb.cmr",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_nb_codec_mode_request_vals_ext, 0x0,
            "codec mode request", HFILL }
        },
        { &hf_amr_wb_cmr,
            { "CMR",           "amr.wb.cmr",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_wb_codec_mode_request_vals_ext, 0x0,
            "codec mode request", HFILL }
        },
        { &hf_amr_reserved,
            { "Reserved",           "amr.reserved",
            FT_UINT8, BASE_DEC, NULL, 0x0f,
            "Reserved bits", HFILL }
        },
        { &hf_amr_payload_decoded_as,
            { "Payload decoded as",           "amr.payload_decoded_as",
            FT_UINT32, BASE_DEC, VALS(amr_encoding_type_value), 0x0,
            "Value of decoding preference", HFILL }
        },
        { &hf_amr_toc_f,
            { "F bit",           "amr.toc.f",
            FT_BOOLEAN, BASE_NONE, TFS(&toc_f_bit_vals), 0x0,
            NULL, HFILL }
        },
        { &hf_amr_nb_toc_ft,
            { "FT bits",           "amr.nb.toc.ft",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_nb_codec_mode_vals_ext, 0x0,
            "Frame type index", HFILL }
        },
        { &hf_amr_wb_toc_ft,
            { "FT bits",           "amr.wb.toc.ft",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_wb_codec_mode_vals_ext, 0x0,
            "Frame type index", HFILL }
        },
        { &hf_amr_toc_q,
            { "Q bit",           "amr.toc.q",
            FT_BOOLEAN, BASE_NONE, TFS(&toc_q_bit_vals), 0x0,
            "Frame quality indicator bit", HFILL }
        },
        { &hf_amr_speech_data,
            { "Speech data",           "amr.speech_data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_amr_frame_data,
            { "Frame Data",           "amr.frame_data",
            FT_BYTES, BASE_NONE, NULL, 0x0,
            NULL, HFILL }
        },
        { &hf_amr_nb_if1_ft,
            { "Frame Type",           "amr.nb.if1.ft",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_nb_codec_mode_vals_ext, 0xf0,
            NULL, HFILL }
        },
        { &hf_amr_wb_if1_ft,
            { "Frame Type",           "amr.wb.if1.ft",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_wb_codec_mode_vals_ext, 0xf0,
            NULL, HFILL }
        },
        { &hf_amr_nb_if1_mode_req,
            { "Mode Type request",           "amr.nb.if1.modereq",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_nb_codec_mode_request_vals_ext, 0xe0,
            NULL, HFILL }
        },
        { &hf_amr_wb_if1_mode_req,
            { "Mode Type request",           "amr.wb.if1.modereq",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_wb_codec_mode_request_vals_ext, 0x0f,
            NULL, HFILL }
        },
        { &hf_amr_if1_sti,
            { "SID Type Indicator",           "amr.if1.sti",
            FT_BOOLEAN, 8, TFS(&amr_sti_vals), 0x10,
            NULL, HFILL }
        },
        { &hf_amr_nb_if1_sti_mode_ind,
            { "Mode Type indication",           "amr.nb.if1.stimodeind",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_nb_codec_mode_vals_ext, 0x0e,
            NULL, HFILL }
        },
        { &hf_amr_wb_if1_sti_mode_ind,
            { "Mode Type indication",           "amr.wb.if1.stimodeind",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_wb_codec_mode_vals_ext, 0x0f,
            NULL, HFILL }
        },
        { &hf_amr_nb_if1_mode_ind,
            { "Mode Type indication",           "amr.nb.if1.modeind",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_nb_codec_mode_vals_ext, 0x07,
            NULL, HFILL }
        },
        { &hf_amr_wb_if1_mode_ind,
            { "Mode Type indication",           "amr.wb.if1.modeind",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_wb_codec_mode_vals_ext, 0xf0,
            NULL, HFILL }
        },
        { &hf_amr_nb_if2_ft,
            { "Frame Type",           "amr.nb.if2.ft",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_nb_codec_mode_vals_ext, 0x0f,
            NULL, HFILL }
        },
        { &hf_amr_wb_if2_ft,
            { "Frame Type",           "amr.wb.if2.ft",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_wb_codec_mode_vals_ext, 0xf0,
            NULL, HFILL }
        },
        { &hf_amr_if2_sti,
            { "SID Type Indicator",           "amr.if2.sti",
            FT_BOOLEAN, 8, TFS(&amr_sti_vals), 0x80,
            NULL, HFILL }
        },
        { &hf_amr_nb_if2_sti_mode_ind,
            { "Mode Type indication",           "amr.nb.if2.stimodeind",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_nb_codec_mode_vals_ext, 0x07,
            NULL, HFILL }
        },
        { &hf_amr_wb_if2_sti_mode_ind,
            { "Mode Type indication",           "amr.wb.if2.stimodeind",
            FT_UINT8, BASE_DEC|BASE_EXT_STRING, &amr_wb_codec_mode_vals_ext, 0x78,
            NULL, HFILL }
        },
        { &hf_amr_if1_fqi,
            { "FQI",           "amr.fqi",
            FT_BOOLEAN, 8, TFS(&toc_q_bit_vals), 0x08,
            "Frame quality indicator bit", HFILL }
        },
    };

/* Setup protocol subtree array */
    static int *ett[] = {
        &ett_amr,
        &ett_amr_toc,
    };

    static ei_register_info ei[] = {
        { &ei_amr_spare_bit_not0, { "amr.spare_bit_not0", PI_PROTOCOL, PI_WARN, "Error:Spare bits not 0", EXPFILL }},
        { &ei_amr_not_enough_data_for_frames, { "amr.not_enough_data_for_frames", PI_MALFORMED, PI_ERROR, "Not enough data for the frames according to TOC", EXPFILL }},
        { &ei_amr_superfluous_data, { "amr.superfluous_data", PI_MALFORMED, PI_ERROR, "Superfluous data remaining", EXPFILL }},
        { &ei_amr_padding_bits_not0, { "amr.padding_bits_not0", PI_MALFORMED, PI_ERROR, "Padding bits error - MUST be 0", EXPFILL }},
        { &ei_amr_padding_bits_correct, { "amr.padding_bits_correct", PI_PROTOCOL, PI_NOTE, "Padding bits correct", EXPFILL }},
        { &ei_amr_reserved, { "amr.reserved.not_zero", PI_PROTOCOL, PI_WARN, "Reserved != 0, wrongly encoded or not octet aligned. Decoding as bandwidth-efficient mode", EXPFILL }},
    };

    static const enum_val_t encoding_types[] = {
        {"RFC 3267 Byte aligned", "RFC 3267 octet aligned", AMR_OA},
        {"RFC 3267 Bandwidth-efficient", "RFC 3267 BW-efficient", AMR_BE},
        {"AMR IF1", "AMR IF1", AMR_IF1},
        {"AMR IF2", "AMR IF2", AMR_IF2},
        {NULL, NULL, -1}
    };

    static const enum_val_t modes[] = {
        {"AMR-NB", "Narrowband AMR", AMR_NB},
        {"AMR-WB", "Wideband AMR", AMR_WB},
        {NULL, NULL, -1}
    };

/* Register the protocol name and description */
    proto_amr = proto_register_protocol("Adaptive Multi-Rate","AMR", "amr");
    proto_amr_wb = proto_register_protocol_in_name_only("Adaptive Multi-Rate WB","AMR WB", "amr_wb", proto_amr, FT_PROTOCOL);

/* Required function calls to register the header fields and subtrees used */
    proto_register_field_array(proto_amr, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    expert_amr = expert_register_protocol(proto_amr);
    expert_register_field_array(expert_amr, ei, array_length(ei));
    /* Register a configuration option for port */

    amr_module = prefs_register_protocol(proto_amr, amr_apply_prefs);

    prefs_register_obsolete_preference(amr_module, "dynamic.payload.type");
    prefs_register_obsolete_preference(amr_module, "wb.dynamic.payload.type");

    prefs_register_enum_preference(amr_module, "encoding.version",
                       "Type of AMR encoding of the payload",
                       "Type of AMR encoding of the payload, if not specified "
                       "via SDP",
                       &amr_encoding_type, encoding_types, false);

    prefs_register_enum_preference(amr_module, "mode",
                       "The AMR mode",
                       "The AMR mode",
                       &pref_amr_mode, modes, AMR_NB);

    amr_handle = register_dissector("amr", dissect_amr, proto_amr);
    amr_wb_handle = register_dissector("amr-wb", dissect_amr_wb, proto_amr_wb);
    register_dissector("amr_if1_nb", dissect_amr_nb_if1, proto_amr);
    register_dissector("amr_if1_wb", dissect_amr_wb_if1, proto_amr);
    register_dissector("amr_if2_nb", dissect_amr_nb_if2, proto_amr);
    register_dissector("amr_if2_wb", dissect_amr_wb_if2, proto_amr);

    oid_add_from_string("G.722.2 (AMR-WB) audio capability","0.0.7.7222.1.0");

    amr_default_fmtp = wmem_map_new(wmem_epan_scope(), wmem_str_hash, g_str_equal);
}

/* Register the protocol with Wireshark */
void
proto_reg_handoff_amr(void)
{
    dissector_handle_t  amr_name_handle;
    amr_capability_t   *ftr;

    dissector_add_string("rtp_dyn_payload_type","AMR", amr_handle);
    dissector_add_string("rtp_dyn_payload_type","AMR-WB", amr_wb_handle);

    dissector_add_uint_range_with_preference("rtp.pt", "", amr_handle);
    dissector_add_uint_range_with_preference("rtp.pt", "", amr_wb_handle);

    /*
     * Register H.245 Generic parameter name(s)
     */
    amr_name_handle = create_dissector_handle(dissect_amr_name, proto_amr);
    for (ftr=amr_capability_tab; ftr->id; ftr++) {
        if (ftr->name)
            dissector_add_string("h245.gef.name", ftr->id, amr_name_handle);
        if (ftr->content_pdu)
            dissector_add_string("h245.gef.content", ftr->id,
                         create_dissector_handle(ftr->content_pdu, proto_amr));
    }
    /*  Activate the next line for testing with the randpkt tool
        dissector_add_uint_with_preference("udp.port", 55555, amr_handle);
    */
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */