path: root/epan/dissectors/asn1/pres/packet-pres-template.c

/* packet-pres.c
 * Routine to dissect ISO 8823 OSI Presentation Protocol packets
 * Based on the dissector by
 * Yuriy Sidelnikov <YSidelnikov@hotmail.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/exceptions.h>
#include <epan/prefs.h>
#include <epan/conversation.h>
#include <epan/expert.h>
#include <epan/uat.h>
#include <wsutil/array.h>

#include <epan/asn1.h>
#include <epan/oids.h>
#include "packet-ber.h"
#include "packet-ses.h"
#include "packet-pres.h"
#include "packet-rtse.h"


#define PNAME  "ISO 8823 OSI Presentation Protocol"
#define PSNAME "PRES"
#define PFNAME "pres"

#define CLPNAME  "ISO 9576-1 OSI Connectionless Presentation Protocol"
#define CLPSNAME "CLPRES"
#define CLPFNAME "clpres"

void proto_register_pres(void);
void proto_reg_handoff_pres(void);

/* Initialize the protocol and registered fields */
static int proto_pres;

/* Initialize the connectionless protocol */
static int proto_clpres;

/*      pointers for acse dissector  */
proto_tree *global_tree;
packet_info *global_pinfo;

static const char *abstract_syntax_name_oid;
static uint32_t presentation_context_identifier;

/* to keep track of presentation context identifiers and protocol-oids */
typedef struct _pres_ctx_oid_t {
	uint32_t ctx_id;
	char *oid;
	uint32_t idx;
} pres_ctx_oid_t;
static wmem_map_t *pres_ctx_oid_table;

typedef struct _pres_user_t {
   unsigned ctx_id;
   char *oid;
} pres_user_t;

static pres_user_t *pres_users;
static unsigned num_pres_users;

static int hf_pres_CP_type;
static int hf_pres_CPA_PPDU;
static int hf_pres_Abort_type;
static int hf_pres_CPR_PPDU;
static int hf_pres_Typed_data_type;

#include "packet-pres-hf.c"

/* Initialize the subtree pointers */
static int ett_pres;

#include "packet-pres-ett.c"

static expert_field ei_pres_dissector_not_available;
static expert_field ei_pres_wrong_spdu_type;
static expert_field ei_pres_invalid_offset;

UAT_DEC_CB_DEF(pres_users, ctx_id, pres_user_t)
UAT_CSTRING_CB_DEF(pres_users, oid, pres_user_t)

static unsigned
pres_ctx_oid_hash(const void *k)
{
	const pres_ctx_oid_t *pco=(const pres_ctx_oid_t *)k;
	return pco->ctx_id;
}

static int
pres_ctx_oid_equal(const void *k1, const void *k2)
{
	const pres_ctx_oid_t *pco1=(const pres_ctx_oid_t *)k1;
	const pres_ctx_oid_t *pco2=(const pres_ctx_oid_t *)k2;
	return (pco1->ctx_id==pco2->ctx_id && pco1->idx==pco2->idx);
}

static void
register_ctx_id_and_oid(packet_info *pinfo _U_, uint32_t idx, const char *oid)
{
	pres_ctx_oid_t *pco, *tmppco;
	conversation_t *conversation;

	if (!oid) {
		/* we did not get any oid name, malformed packet? */
		return;
	}

	pco=wmem_new(wmem_file_scope(), pres_ctx_oid_t);
	pco->ctx_id=idx;
	pco->oid=wmem_strdup(wmem_file_scope(), oid);
	conversation=find_conversation_pinfo(pinfo, 0);
	if (conversation) {
		pco->idx = conversation->conv_index;
	} else {
		pco->idx = 0;
	}

	/* if this ctx already exists, remove the old one first */
	tmppco=(pres_ctx_oid_t *)wmem_map_lookup(pres_ctx_oid_table, pco);
	if (tmppco) {
		wmem_map_remove(pres_ctx_oid_table, tmppco);
	}
	wmem_map_insert(pres_ctx_oid_table, pco, pco);
}

static char *
find_oid_in_users_table(packet_info *pinfo, uint32_t ctx_id)
{
	unsigned i;

	for (i = 0; i < num_pres_users; i++) {
		pres_user_t *u = &(pres_users[i]);

		if (u->ctx_id == ctx_id) {
			/* Register oid so other dissectors can find this connection */
			register_ctx_id_and_oid(pinfo, u->ctx_id, u->oid);
			return u->oid;
		}
	}

	return NULL;
}

char *
find_oid_by_pres_ctx_id(packet_info *pinfo, uint32_t idx)
{
	pres_ctx_oid_t pco, *tmppco;
	conversation_t *conversation;

	pco.ctx_id=idx;
	conversation=find_conversation_pinfo(pinfo, 0);
	if (conversation) {
		pco.idx = conversation->conv_index;
	} else {
		pco.idx = 0;
	}

	tmppco=(pres_ctx_oid_t *)wmem_map_lookup(pres_ctx_oid_table, &pco);
	if (tmppco) {
		return tmppco->oid;
	}

	return find_oid_in_users_table(pinfo, idx);
}

static void *
pres_copy_cb(void *dest, const void *orig, size_t len _U_)
{
	pres_user_t *u = (pres_user_t *)dest;
	const pres_user_t *o = (const pres_user_t *)orig;

	u->ctx_id = o->ctx_id;
	u->oid = g_strdup(o->oid);

	return dest;
}

static void
pres_free_cb(void *r)
{
	pres_user_t *u = (pres_user_t *)r;

	g_free(u->oid);
}


#include "packet-pres-fn.c"


/*
 * Dissect an PPDU.
 */
static int
dissect_ppdu(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree, struct SESSION_DATA_STRUCTURE* local_session)
{
	proto_item *ti;
	proto_tree *pres_tree;
	struct SESSION_DATA_STRUCTURE* session;
	asn1_ctx_t asn1_ctx;
	asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, true, pinfo);

	/* do we have spdu type from the session dissector?  */
	if (local_session == NULL) {
		proto_tree_add_expert(tree, pinfo, &ei_pres_wrong_spdu_type, tvb, offset, -1);
		return 0;
	}

	session = local_session;
	if (session->spdu_type == 0) {
		proto_tree_add_expert_format(tree, pinfo, &ei_pres_wrong_spdu_type, tvb, offset, -1,
			"Internal error:wrong spdu type %x from session dissector.",session->spdu_type);
		return 0;
	}

	/*  set up type of PPDU */
	col_add_str(pinfo->cinfo, COL_INFO,
		    val_to_str_ext(session->spdu_type, &ses_vals_ext, "Unknown PPDU type (0x%02x)"));

	asn1_ctx.private_data = session;

	ti = proto_tree_add_item(tree, proto_pres, tvb, offset, -1, ENC_NA);
	pres_tree = proto_item_add_subtree(ti, ett_pres);

	switch (session->spdu_type) {
		case SES_CONNECTION_REQUEST:
			offset = dissect_pres_CP_type(false, tvb, offset, &asn1_ctx, pres_tree, hf_pres_CP_type);
			break;
		case SES_CONNECTION_ACCEPT:
			offset = dissect_pres_CPA_PPDU(false, tvb, offset, &asn1_ctx, pres_tree, hf_pres_CPA_PPDU);
			break;
		case SES_ABORT:
		case SES_ABORT_ACCEPT:
			offset = dissect_pres_Abort_type(false, tvb, offset, &asn1_ctx, pres_tree, hf_pres_Abort_type);
			break;
		case SES_DATA_TRANSFER:
			offset = dissect_pres_CPC_type(false, tvb, offset, &asn1_ctx, pres_tree, hf_pres_user_data);
			break;
		case SES_TYPED_DATA:
			offset = dissect_pres_Typed_data_type(false, tvb, offset, &asn1_ctx, pres_tree, hf_pres_Typed_data_type);
			break;
		case SES_RESYNCHRONIZE:
			offset = dissect_pres_RS_PPDU(false, tvb, offset, &asn1_ctx, pres_tree, -1);
			break;
		case SES_RESYNCHRONIZE_ACK:
			offset = dissect_pres_RSA_PPDU(false, tvb, offset, &asn1_ctx, pres_tree, -1);
			break;
		case SES_REFUSE:
			offset = dissect_pres_CPR_PPDU(false, tvb, offset, &asn1_ctx, pres_tree, hf_pres_CPR_PPDU);
			break;
		default:
			offset = dissect_pres_CPC_type(false, tvb, offset, &asn1_ctx, pres_tree, hf_pres_user_data);
			break;
	}

	return offset;
}

static int
dissect_pres(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data)
{
	int offset = 0, old_offset;
	struct SESSION_DATA_STRUCTURE* session;

	session = ((struct SESSION_DATA_STRUCTURE*)data);

	/* first, try to check length   */
	/* do we have at least 4 bytes  */
	if (!tvb_bytes_exist(tvb, 0, 4)) {
		if (session && session->spdu_type != SES_MAJOR_SYNC_POINT) {
			proto_tree_add_item(parent_tree, hf_pres_user_data, tvb, offset,
					    tvb_reported_length_remaining(tvb,offset), ENC_NA);
			return 0;  /* no, it isn't a presentation PDU */
		}
	}

	/* save pointers for calling the acse dissector  */
	global_tree = parent_tree;
	global_pinfo = pinfo;

	/* if the session unit-data packet then we process it */
	/* as a connectionless presentation protocol unit data */
	if (session && session->spdu_type == CLSES_UNIT_DATA) {
		proto_tree * clpres_tree = NULL;
		proto_item *ti;

		col_set_str(pinfo->cinfo, COL_PROTOCOL, "CL-PRES");
  		col_clear(pinfo->cinfo, COL_INFO);

		if (parent_tree) {
			ti = proto_tree_add_item(parent_tree, proto_clpres, tvb, offset, -1, ENC_NA);
			clpres_tree = proto_item_add_subtree(ti, ett_pres);
		}

		/* dissect the packet */
		dissect_UD_type_PDU(tvb, pinfo, clpres_tree, NULL);
		return tvb_captured_length(tvb);
	}

	/*  we can't make any additional checking here   */
	/*  postpone it before dissector will have more information */

	col_set_str(pinfo->cinfo, COL_PROTOCOL, "PRES");
  	col_clear(pinfo->cinfo, COL_INFO);

	if (session && session->spdu_type == SES_MAJOR_SYNC_POINT) {
		/* This is a reassembly initiated in packet-ses */
		char *oid = find_oid_by_pres_ctx_id (pinfo, session->pres_ctx_id);
		if (oid) {
			call_ber_oid_callback (oid, tvb, offset, pinfo, parent_tree, session);
		} else {
			proto_tree_add_item(parent_tree, hf_pres_user_data, tvb, offset,
					    tvb_reported_length_remaining(tvb,offset), ENC_NA);
		}
		return tvb_captured_length(tvb);
	}

	while (tvb_reported_length_remaining(tvb, offset) > 0) {
		old_offset = offset;
		offset = dissect_ppdu(tvb, offset, pinfo, parent_tree, session);
		if (offset <= old_offset) {
			proto_tree_add_expert(parent_tree, pinfo, &ei_pres_invalid_offset, tvb, offset, -1);
			break;
		}
	}

	return tvb_captured_length(tvb);
}


/*--- proto_register_pres -------------------------------------------*/
void proto_register_pres(void) {

  /* List of fields */
  static hf_register_info hf[] = {
    { &hf_pres_CP_type,
      { "CP-type", "pres.cptype",
        FT_NONE, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_pres_CPA_PPDU,
      { "CPA-PPDU", "pres.cpapdu",
        FT_NONE, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_pres_Abort_type,
      { "Abort type", "pres.aborttype",
        FT_UINT32, BASE_DEC, VALS(pres_Abort_type_vals), 0,
        NULL, HFILL }},
    { &hf_pres_CPR_PPDU,
      { "CPR-PPDU", "pres.cprtype",
        FT_UINT32, BASE_DEC, VALS(pres_CPR_PPDU_vals), 0,
        NULL, HFILL }},
    { &hf_pres_Typed_data_type,
      { "Typed data type", "pres.Typed_data_type",
        FT_UINT32, BASE_DEC, VALS(pres_Typed_data_type_vals), 0,
        NULL, HFILL }},

#include "packet-pres-hfarr.c"
  };

  /* List of subtrees */
  static int *ett[] = {
		&ett_pres,
#include "packet-pres-ettarr.c"
  };

  static ei_register_info ei[] = {
     { &ei_pres_dissector_not_available, { "pres.dissector_not_available", PI_UNDECODED, PI_WARN, "Dissector is not available", EXPFILL }},
     { &ei_pres_wrong_spdu_type, { "pres.wrong_spdu_type", PI_PROTOCOL, PI_WARN, "Internal error:can't get spdu type from session dissector", EXPFILL }},
     { &ei_pres_invalid_offset, { "pres.invalid_offset", PI_MALFORMED, PI_ERROR, "Internal error:can't get spdu type from session dissector", EXPFILL }},
  };

  static uat_field_t users_flds[] = {
    UAT_FLD_DEC(pres_users,ctx_id,"Context Id","Presentation Context Identifier"),
    UAT_FLD_CSTRING(pres_users,oid,"Syntax Name OID","Abstract Syntax Name (Object Identifier)"),
    UAT_END_FIELDS
  };

  uat_t* users_uat = uat_new("PRES Users Context List",
                             sizeof(pres_user_t),
                             "pres_context_list",
                             true,
                             &pres_users,
                             &num_pres_users,
                             UAT_AFFECTS_DISSECTION, /* affects dissection of packets, but not set of named fields */
                             "ChPresContextList",
                             pres_copy_cb,
                             NULL,
                             pres_free_cb,
                             NULL,
                             NULL,
                             users_flds);

  expert_module_t* expert_pres;
  module_t *pres_module;

  /* Register protocol */
  proto_pres = proto_register_protocol(PNAME, PSNAME, PFNAME);
  register_dissector("pres", dissect_pres, proto_pres);

  /* Register connectionless protocol (just for the description) */
  proto_clpres = proto_register_protocol(CLPNAME, CLPSNAME, CLPFNAME);

  /* Register fields and subtrees */
  proto_register_field_array(proto_pres, hf, array_length(hf));
  proto_register_subtree_array(ett, array_length(ett));
  expert_pres = expert_register_protocol(proto_pres);
  expert_register_field_array(expert_pres, ei, array_length(ei));
  pres_ctx_oid_table = wmem_map_new_autoreset(wmem_epan_scope(), wmem_file_scope(), pres_ctx_oid_hash, pres_ctx_oid_equal);

  pres_module = prefs_register_protocol(proto_pres, NULL);

  prefs_register_uat_preference(pres_module, "users_table", "Users Context List",
                                "A table that enumerates user protocols to be used against"
                                " specific presentation context identifiers",
                                users_uat);
}


/*--- proto_reg_handoff_pres ---------------------------------------*/
void proto_reg_handoff_pres(void) {

/*	register_ber_oid_dissector("0.4.0.0.1.1.1.1", dissect_pres, proto_pres,
	  "itu-t(0) identified-organization(4) etsi(0) mobileDomain(0) gsm-Network(1) abstractSyntax(1) pres(1) version1(1)"); */

}