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wireshark/epan/dissectors/packet-sscop.c

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/* packet-sscop.c
* Routines for SSCOP (Q.2110, Q.SAAL) frame disassembly
* Guy Harris <guy@alum.mit.edu>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998
*
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/prefs.h>
#include <epan/proto_data.h>
#include <wiretap/wtap.h>
#include "packet-sscop.h"
void proto_register_sscop(void);
void proto_reg_handoff_sscop(void);
int proto_sscop = -1;
static int hf_sscop_type = -1;
static int hf_sscop_sq = -1;
static int hf_sscop_mr = -1;
static int hf_sscop_s = -1;
static int hf_sscop_ps = -1;
static int hf_sscop_r = -1;
static int hf_sscop_stat_s = -1;
static int hf_sscop_pad_length = -1;
static int hf_sscop_source = -1;
/* static int hf_sscop_stat_count = -1; */
static gint ett_sscop = -1;
static gint ett_stat = -1;
static dissector_handle_t q2931_handle;
static dissector_handle_t data_handle;
static dissector_handle_t sscf_nni_handle;
static dissector_handle_t alcap_handle;
static dissector_handle_t nbap_handle;
static dissector_handle_t sscop_handle;
static const enum_val_t sscop_payload_dissector_options[] = {
{ "data", "Data (no further dissection)", DATA_DISSECTOR },
{ "Q.2931", "Q.2931", Q2931_DISSECTOR },
{ "SSCF-NNI", "SSCF-NNI (MTP3-b)", SSCF_NNI_DISSECTOR },
{ "ALCAP", "ALCAP", ALCAP_DISSECTOR },
{ "NBAP", "NBAP", NBAP_DISSECTOR },
{ NULL, NULL, 0 }
};
static guint sscop_payload_dissector = Q2931_DISSECTOR;
static dissector_handle_t default_handle;
static sscop_info_t sscop_info;
/*
* See
*
* http://web.archive.org/web/20150408122122/http://www.protocols.com/pbook/atmsig.htm
*
* for some information on SSCOP, although, alas, not the actual PDU
* type values - those I got from the FreeBSD 3.2 ATM code.
*/
/*
* SSCOP PDU types.
*/
#define SSCOP_TYPE_MASK 0x0f
#define SSCOP_BGN 0x01 /* Begin */
#define SSCOP_BGAK 0x02 /* Begin Acknowledge */
#define SSCOP_END 0x03 /* End */
#define SSCOP_ENDAK 0x04 /* End Acknowledge */
#define SSCOP_RS 0x05 /* Resynchronization */
#define SSCOP_RSAK 0x06 /* Resynchronization Acknowledge */
#define SSCOP_BGREJ 0x07 /* Begin Reject */
#define SSCOP_SD 0x08 /* Sequenced Data */
#if 0
#define SSCOP_SDP 0x09 /* Sequenced Data with Poll */
#endif
#define SSCOP_ER 0x09 /* Error Recovery */
#define SSCOP_POLL 0x0a /* Status Request */
#define SSCOP_STAT 0x0b /* Solicited Status Response */
#define SSCOP_USTAT 0x0c /* Unsolicited Status Response */
#define SSCOP_UD 0x0d /* Unnumbered Data */
#define SSCOP_MD 0x0e /* Management Data */
#define SSCOP_ERAK 0x0f /* Error Acknowledge */
#define SSCOP_S 0x10 /* Source bit in End PDU */
/*
* XXX - how to distinguish SDP from ER?
*/
static const value_string sscop_type_vals[] = {
{ SSCOP_BGN, "Begin" },
{ SSCOP_BGAK, "Begin Acknowledge" },
{ SSCOP_END, "End" },
{ SSCOP_ENDAK, "End Acknowledge" },
{ SSCOP_RS, "Resynchronization" },
{ SSCOP_RSAK, "Resynchronization Acknowledge" },
{ SSCOP_BGREJ, "Begin Reject" },
{ SSCOP_SD, "Sequenced Data" },
#if 0
{ SSCOP_SDP, "Sequenced Data with Poll" },
#endif
{ SSCOP_ER, "Error Recovery" },
{ SSCOP_POLL, "Status Request" },
{ SSCOP_STAT, "Solicited Status Response" },
{ SSCOP_USTAT, "Unsolicited Status Response" },
{ SSCOP_UD, "Unnumbered Data" },
{ SSCOP_MD, "Management Data" },
{ SSCOP_ERAK, "Error Acknowledge" },
{ 0, NULL }
};
static value_string_ext sscop_type_vals_ext = VALUE_STRING_EXT_INIT(sscop_type_vals);
/*
* The SSCOP "header" is a trailer, so the "offsets" are computed based
* on the length of the packet.
*/
/*
* PDU type.
*/
#define SSCOP_PDU_TYPE (reported_length - 4) /* single byte */
/*
* Begin PDU, Begin Acknowledge PDU (no N(SQ) in it), Resynchronization
* PDU, Resynchronization Acknowledge PDU (no N(SQ) in it in Q.SAAL),
* Error Recovery PDU, Error Recovery Acknoledge PDU (no N(SQ) in it).
*/
#define SSCOP_N_SQ (reported_length - 5) /* One byte */
#define SSCOP_N_MR (reported_length - 4) /* lower 3 bytes thereof */
/*
* Sequenced Data PDU (no N(PS) in it), Sequenced Data with Poll PDU,
* Poll PDU.
*/
#define SSCOP_N_PS (reported_length - 8) /* lower 3 bytes thereof */
#define SSCOP_N_S (reported_length - 4) /* lower 3 bytes thereof */
/*
* Solicited Status PDU, Unsolicited Status PDU (no N(PS) in it).
*/
#define SSCOP_SS_N_PS (reported_length - 12) /* lower 3 bytes thereof */
#define SSCOP_SS_N_MR (reported_length - 8) /* lower 3 bytes thereof */
#define SSCOP_SS_N_R (reported_length - 4) /* lower 3 bytes thereof */
static void dissect_stat_list(proto_tree *tree, tvbuff_t *tvb,guint h) {
gint n,i;
if ((n = (tvb_reported_length(tvb))/4 - h)) {
tree = proto_tree_add_subtree(tree,tvb,0,n*4,ett_stat,NULL,"SD List");
for (i = 0; i < n; i++) {
proto_tree_add_item(tree, hf_sscop_stat_s, tvb, i*4 + 1,3,ENC_BIG_ENDIAN);
}
}
}
extern void
dissect_sscop_and_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, dissector_handle_t payload_handle)
{
guint reported_length;
proto_item *ti;
proto_tree *sscop_tree = NULL;
guint8 sscop_pdu_type;
int pdu_len;
int pad_len;
tvbuff_t *next_tvb;
reported_length = tvb_reported_length(tvb); /* frame length */
sscop_pdu_type = tvb_get_guint8(tvb, SSCOP_PDU_TYPE);
sscop_info.type = sscop_pdu_type & SSCOP_TYPE_MASK;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "SSCOP");
col_add_str(pinfo->cinfo, COL_INFO, val_to_str_ext(sscop_info.type, &sscop_type_vals_ext,
"Unknown PDU type (0x%02x)"));
/*
* Find the length of the PDU and, if there's any payload and
* padding, the length of the padding.
*/
switch (sscop_info.type) {
case SSCOP_SD:
pad_len = (sscop_pdu_type >> 6) & 0x03;
pdu_len = 4;
break;
case SSCOP_BGN:
case SSCOP_BGAK:
case SSCOP_BGREJ:
case SSCOP_END:
case SSCOP_RS:
#if 0
case SSCOP_SDP:
#endif
pad_len = (sscop_pdu_type >> 6) & 0x03;
sscop_info.payload_len = pdu_len = 8;
break;
case SSCOP_UD:
pad_len = (sscop_pdu_type >> 6) & 0x03;
sscop_info.payload_len = pdu_len = 4;
break;
default:
pad_len = 0;
pdu_len = reported_length; /* No payload, just SSCOP */
sscop_info.payload_len = 0;
break;
}
if (tree) {
ti = proto_tree_add_protocol_format(tree, proto_sscop, tvb,
reported_length - pdu_len,
pdu_len, "SSCOP");
sscop_tree = proto_item_add_subtree(ti, ett_sscop);
proto_tree_add_item(sscop_tree, hf_sscop_type, tvb, SSCOP_PDU_TYPE, 1,ENC_BIG_ENDIAN);
switch (sscop_info.type) {
case SSCOP_BGN:
case SSCOP_RS:
case SSCOP_ER:
proto_tree_add_item(sscop_tree, hf_sscop_sq, tvb, SSCOP_N_SQ, 1,ENC_BIG_ENDIAN);
proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, ENC_BIG_ENDIAN);
break;
case SSCOP_END:
proto_tree_add_string(sscop_tree, hf_sscop_source, tvb, SSCOP_PDU_TYPE, 1,
(sscop_pdu_type & SSCOP_S) ? "SSCOP" : "User");
break;
case SSCOP_BGAK:
case SSCOP_RSAK:
proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, ENC_BIG_ENDIAN);
break;
case SSCOP_ERAK:
proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, ENC_BIG_ENDIAN);
break;
case SSCOP_SD:
proto_tree_add_item(sscop_tree, hf_sscop_s, tvb, SSCOP_N_S + 1, 3, ENC_BIG_ENDIAN);
break;
#if 0
case SSCOP_SDP:
#endif
case SSCOP_POLL:
proto_tree_add_item(sscop_tree, hf_sscop_ps, tvb, SSCOP_N_PS + 1, 3,ENC_BIG_ENDIAN);
proto_tree_add_item(sscop_tree, hf_sscop_s, tvb, SSCOP_N_S + 1, 3,ENC_BIG_ENDIAN);
break;
case SSCOP_STAT:
proto_tree_add_item(sscop_tree, hf_sscop_ps, tvb, SSCOP_SS_N_PS + 1, 3,ENC_BIG_ENDIAN);
proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_SS_N_MR + 1, 3, ENC_BIG_ENDIAN);
proto_tree_add_item(sscop_tree, hf_sscop_r, tvb, SSCOP_SS_N_R + 1, 3,ENC_BIG_ENDIAN);
dissect_stat_list(sscop_tree,tvb,3);
break;
case SSCOP_USTAT:
proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_SS_N_MR + 1, 3, ENC_BIG_ENDIAN);
proto_tree_add_item(sscop_tree, hf_sscop_r, tvb, SSCOP_SS_N_R + 1, 3,ENC_BIG_ENDIAN);
dissect_stat_list(sscop_tree,tvb,2);
break;
}
}
/*
* Dissect the payload, if any.
*
* XXX - what about a Management Data PDU?
*/
switch (sscop_info.type) {
case SSCOP_SD:
case SSCOP_UD:
case SSCOP_BGN:
case SSCOP_BGAK:
case SSCOP_BGREJ:
case SSCOP_END:
case SSCOP_RS:
#if 0
case SSCOP_SDP:
#endif
if (tree) {
proto_tree_add_uint(sscop_tree, hf_sscop_pad_length, tvb, SSCOP_PDU_TYPE, 1, pad_len);
}
/*
* Compute length of data in PDU - subtract the trailer length
* and the pad length from the reported length.
*/
reported_length -= (pdu_len + pad_len);
if (reported_length != 0) {
/*
* We know that we have all of the payload, because we know we have
* at least 4 bytes of data after the payload, i.e. the SSCOP trailer.
* Therefore, we know that the captured length of the payload is
* equal to the length of the payload.
*/
next_tvb = tvb_new_subset_length(tvb, 0, reported_length);
if (sscop_info.type == SSCOP_SD)
{
call_dissector(payload_handle, next_tvb, pinfo, tree);
}
break;
}
}
}
static int dissect_sscop(tvbuff_t* tvb, packet_info* pinfo,proto_tree* tree, void* data _U_)
{
struct _sscop_payload_info *p_sscop_info;
dissector_handle_t subdissector;
/* Look for packet info for subdissector information */
p_sscop_info = (struct _sscop_payload_info *)p_get_proto_data(wmem_file_scope(), pinfo, proto_sscop, 0);
if ( p_sscop_info
&& ( subdissector = p_sscop_info->subdissector )
&& ( subdissector == data_handle
|| subdissector == q2931_handle
|| subdissector == sscf_nni_handle
|| subdissector == alcap_handle
|| subdissector == nbap_handle) )
dissect_sscop_and_payload(tvb,pinfo,tree,subdissector);
else
dissect_sscop_and_payload(tvb,pinfo,tree,default_handle);
return tvb_captured_length(tvb);
}
/* Make sure handles for various protocols are initialized */
static void initialize_handles_once(void) {
static gboolean initialized = FALSE;
if (!initialized) {
q2931_handle = find_dissector("q2931");
data_handle = find_dissector("data");
sscf_nni_handle = find_dissector("sscf-nni");
alcap_handle = find_dissector("alcap");
nbap_handle = find_dissector("nbap");
initialized = TRUE;
}
}
gboolean sscop_allowed_subdissector(dissector_handle_t handle)
{
initialize_handles_once();
if (handle == q2931_handle || handle == data_handle
|| handle == sscf_nni_handle || handle == alcap_handle
|| handle == nbap_handle)
return TRUE;
return FALSE;
}
void
proto_reg_handoff_sscop(void)
{
static gboolean prefs_initialized = FALSE;
if (!prefs_initialized) {
initialize_handles_once();
dissector_add_uint_range_with_preference("udp.port", "", sscop_handle);
prefs_initialized = TRUE;
}
dissector_add_uint("atm.aal5.type", TRAF_SSCOP, sscop_handle);
switch(sscop_payload_dissector) {
case DATA_DISSECTOR: default_handle = data_handle; break;
case Q2931_DISSECTOR: default_handle = q2931_handle; break;
case SSCF_NNI_DISSECTOR: default_handle = sscf_nni_handle; break;
case ALCAP_DISSECTOR: default_handle = alcap_handle; break;
case NBAP_DISSECTOR: default_handle = nbap_handle; break;
}
}
void
proto_register_sscop(void)
{
static hf_register_info hf[] = {
{ &hf_sscop_type, { "PDU Type", "sscop.type", FT_UINT8, BASE_HEX|BASE_EXT_STRING, &sscop_type_vals_ext, SSCOP_TYPE_MASK, NULL, HFILL }},
{ &hf_sscop_sq, { "N(SQ)", "sscop.sq", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_sscop_mr, { "N(MR)", "sscop.mr", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_sscop_s, { "N(S)", "sscop.s", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_sscop_ps, { "N(PS)", "sscop.ps", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_sscop_r, { "N(R)", "sscop.r", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_sscop_stat_s, { "N(S)", "sscop.stat.s", FT_UINT24, BASE_DEC, NULL, 0x0,NULL, HFILL }},
{ &hf_sscop_pad_length, { "Pad length", "sscop.pad_length", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_sscop_source, { "Source", "sscop.source", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL }},
#if 0
{ &hf_sscop_stat_count, { "Number of NACKed pdus", "sscop.stat.count", FT_UINT32, BASE_DEC, NULL, 0x0,NULL, HFILL }}
#endif
};
static gint *ett[] = {
&ett_sscop,
&ett_stat
};
module_t *sscop_module;
proto_sscop = proto_register_protocol("SSCOP", "SSCOP", "sscop");
proto_register_field_array(proto_sscop, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
sscop_handle = register_dissector("sscop", dissect_sscop, proto_sscop);
sscop_module = prefs_register_protocol(proto_sscop, proto_reg_handoff_sscop);
prefs_register_enum_preference(sscop_module, "payload",
"SSCOP payload protocol",
"SSCOP payload (dissector to call on SSCOP payload)",
(gint *)&sscop_payload_dissector,
sscop_payload_dissector_options, FALSE);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local Variables:
* c-basic-offset: 2
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=2 tabstop=8 expandtab:
* :indentSize=2:tabSize=8:noTabs=true:
*/
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