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 /* Initialize the protocol and registered fields */
  23 static int proto_g723                                   = -1;
  24 static int hf_g723_frame_size_and_codec = -1;
  25 static int hf_g723_lpc_B5_B0                    = -1;
  26
  27 /* Initialize the subtree pointers */
  28 static int ett_g723 = -1;
  29
  30
  31 /*               RFC 3551
  32         The least significant two bits of the first
  33         octet in the frame determine the frame size and codec type:
  34          bits  content                      octets/frame
  35          00    high-rate speech (6.3 kb/s)            24
  36          01    low-rate speech  (5.3 kb/s)            20
  37          10    SID frame                               4
  38          11    reserved
  39
  40  */
  41 static const value_string g723_frame_size_and_codec_type_value[] = {
  42         {0,                     "High-rate speech (6.3 kb/s)"},
  43         {1,                     "Low-rate speech  (5.3 kb/s)"}, /* Not coded */
  44         {2,                     "SID frame"},
  45         {3,                     "Reserved"},
  46         { 0,    NULL }
  47 };
  48
  49
  50 /* Dissection */
  51 static int
  52 dissect_g723(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  53 {
  54         int offset = 0;
  55         guint octet;
  56
  57         proto_item *ti;
  58         proto_tree *g723_tree;
  59
  60         col_set_str(pinfo->cinfo, COL_PROTOCOL, "G.723.1");
  61         if (tree) {
  62                 ti = proto_tree_add_item(tree, proto_g723, tvb, 0, -1, ENC_NA);
  63
  64                 g723_tree = proto_item_add_subtree(ti, ett_g723);
  65
  66                 octet = tvb_get_guint8(tvb,offset);
  67                 proto_tree_add_item(g723_tree, hf_g723_frame_size_and_codec, tvb, offset, 1, ENC_BIG_ENDIAN);
  68                 proto_tree_add_item(g723_tree, hf_g723_lpc_B5_B0, tvb, offset, 1, ENC_BIG_ENDIAN);
  69
  70                 if ((octet & 0x1) == 1 ) /* Low rate */
  71                         return tvb_captured_length(tvb);
  72         }/* if tree */
  73
  74         return tvb_captured_length(tvb);
  75 }
  76
  77 void
  78 proto_reg_handoff_g723(void)
  79 {
  80         dissector_handle_t g723_handle;
  81
  82         g723_handle = create_dissector_handle(dissect_g723, proto_g723);
  83
  84         dissector_add_uint("rtp.pt", PT_G723, g723_handle);
  85
  86 }
  87
  88 void
  89 proto_register_g723(void)
  90 {
  91
  92
  93         static hf_register_info hf[] = {
  94                 { &hf_g723_frame_size_and_codec,
  95                         { "Frame size and codec type", "g723.frame_size_and_codec",
  96                         FT_UINT8, BASE_HEX, VALS(g723_frame_size_and_codec_type_value), 0x03,
  97                         "RATEFLAG_B0", HFILL }
  98                 },
  99                 { &hf_g723_lpc_B5_B0,
 100                         { "LPC_B5...LPC_B0",           "g723.lpc.b5b0",
 101                         FT_UINT8, BASE_HEX, NULL, 0xfc,
 102                         NULL, HFILL }
 103                 },
 104
 105         };
 106
 107         static gint *ett[] = {
 108                 &ett_g723,
 109         };
 110
 111         proto_g723 = proto_register_protocol("G.723","G.723", "g723");
 112
 113         proto_register_field_array(proto_g723, hf, array_length(hf));
 114         proto_register_subtree_array(ett, array_length(ett));
 115
 116 }
 117
 118 /*
 119  * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 120  *
 121  * Local variables:
 122  * c-basic-offset: 8
 123  * tab-width: 8
 124  * indent-tabs-mode: t
 125  * End:
 126  *
 127  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 128  * :indentSize=8:tabSize=8:noTabs=false:
 129  */