epan/dissectors/packet-g723.c

   1 /* packet-g723.c
   2  * Routines for G.723 dissection
   3  * Copyright 2005, Anders Broman <anders.broman[at]ericsson.com>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  *
  11  * References:
  12  */
  13
  14 #include "config.h"
  15
  16 #include <epan/packet.h>
  17 #include <epan/rtp_pt.h>
  18
  19 void proto_reg_handoff_g723(void);
  20 void proto_register_g723(void);
  21
  22 static dissector_handle_t g723_handle;
  23
  24 /* Initialize the protocol and registered fields */
  25 static int proto_g723;
  26 static int hf_g723_frame_size_and_codec;
  27 static int hf_g723_lpc_B5_B0;
  28
  29 /* Initialize the subtree pointers */
  30 static int ett_g723;
  31
  32
  33 /*               RFC 3551
  34         The least significant two bits of the first
  35         octet in the frame determine the frame size and codec type:
  36          bits  content                      octets/frame
  37          00    high-rate speech (6.3 kb/s)            24
  38          01    low-rate speech  (5.3 kb/s)            20
  39          10    SID frame                               4
  40          11    reserved
  41
  42  */
  43 static const value_string g723_frame_size_and_codec_type_value[] = {
  44         {0,                     "High-rate speech (6.3 kb/s)"},
  45         {1,                     "Low-rate speech  (5.3 kb/s)"}, /* Not coded */
  46         {2,                     "SID frame"},
  47         {3,                     "Reserved"},
  48         { 0,    NULL }
  49 };
  50
  51
  52 /* Dissection */
  53 static int
  54 dissect_g723(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  55 {
  56         int offset = 0;
  57         unsigned octet;
  58
  59         proto_item *ti;
  60         proto_tree *g723_tree;
  61
  62         col_set_str(pinfo->cinfo, COL_PROTOCOL, "G.723.1");
  63         if (tree) {
  64                 ti = proto_tree_add_item(tree, proto_g723, tvb, 0, -1, ENC_NA);
  65
  66                 g723_tree = proto_item_add_subtree(ti, ett_g723);
  67
  68                 octet = tvb_get_uint8(tvb,offset);
  69                 proto_tree_add_item(g723_tree, hf_g723_frame_size_and_codec, tvb, offset, 1, ENC_BIG_ENDIAN);
  70                 proto_tree_add_item(g723_tree, hf_g723_lpc_B5_B0, tvb, offset, 1, ENC_BIG_ENDIAN);
  71
  72                 if ((octet & 0x1) == 1 ) /* Low rate */
  73                         return tvb_captured_length(tvb);
  74         }/* if tree */
  75
  76         return tvb_captured_length(tvb);
  77 }
  78
  79 void
  80 proto_reg_handoff_g723(void)
  81 {
  82         dissector_add_uint("rtp.pt", PT_G723, g723_handle);
  83
  84 }
  85
  86 void
  87 proto_register_g723(void)
  88 {
  89
  90
  91         static hf_register_info hf[] = {
  92                 { &hf_g723_frame_size_and_codec,
  93                         { "Frame size and codec type", "g723.frame_size_and_codec",
  94                         FT_UINT8, BASE_HEX, VALS(g723_frame_size_and_codec_type_value), 0x03,
  95                         "RATEFLAG_B0", HFILL }
  96                 },
  97                 { &hf_g723_lpc_B5_B0,
  98                         { "LPC_B5...LPC_B0",           "g723.lpc.b5b0",
  99                         FT_UINT8, BASE_HEX, NULL, 0xfc,
 100                         NULL, HFILL }
 101                 },
 102
 103         };
 104
 105         static int *ett[] = {
 106                 &ett_g723,
 107         };
 108
 109         proto_g723 = proto_register_protocol("G.723","G.723", "g723");
 110
 111         proto_register_field_array(proto_g723, hf, array_length(hf));
 112         proto_register_subtree_array(ett, array_length(ett));
 113
 114         g723_handle = register_dissector("g723", dissect_g723, proto_g723);
 115 }
 116
 117 /*
 118  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 119  *
 120  * Local variables:
 121  * c-basic-offset: 8
 122  * tab-width: 8
 123  * indent-tabs-mode: t
 124  * End:
 125  *
 126  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 127  * :indentSize=8:tabSize=8:noTabs=false:
 128  */