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/* Common bits for RAN message handling */
/*
* (C) 2019 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
* All Rights Reserved
*
* Author: Neels Hofmeyr
*
* SPDX-License-Identifier: GPL-2.0+
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <osmocom/core/utils.h>
#include <osmocom/msc/ran_msg.h>
const struct value_string ran_msg_type_names[] = {
{ RAN_MSG_NONE, "NONE" },
{ RAN_MSG_COMPL_L3, "COMPL_L3" },
{ RAN_MSG_DTAP, "DTAP" },
{ RAN_MSG_CLEAR_COMMAND, "CLEAR_COMMAND" },
{ RAN_MSG_CLEAR_REQUEST, "CLEAR_REQUEST" },
{ RAN_MSG_CLEAR_COMPLETE, "CLEAR_COMPLETE" },
{ RAN_MSG_CLASSMARK_REQUEST, "CLASSMARK_REQUEST" },
{ RAN_MSG_CLASSMARK_UPDATE, "CLASSMARK_UPDATE" },
{ RAN_MSG_CIPHER_MODE_COMMAND, "CIPHER_MODE_COMMAND" },
{ RAN_MSG_CIPHER_MODE_COMPLETE, "CIPHER_MODE_COMPLETE" },
{ RAN_MSG_CIPHER_MODE_REJECT, "CIPHER_MODE_REJECT" },
{ RAN_MSG_COMMON_ID, "COMMON_ID" },
{ RAN_MSG_ASSIGNMENT_COMMAND, "ASSIGNMENT_COMMAND" },
{ RAN_MSG_ASSIGNMENT_COMPLETE, "ASSIGNMENT_COMPLETE" },
{ RAN_MSG_ASSIGNMENT_FAILURE, "ASSIGNMENT_FAILURE" },
{ RAN_MSG_SAPI_N_REJECT, "SAPI_N_REJECT" },
{ RAN_MSG_LCLS_STATUS, "LCLS_STATUS" },
{ RAN_MSG_LCLS_BREAK_REQ, "LCLS_BREAK_REQ" },
{ RAN_MSG_HANDOVER_COMMAND, "HANDOVER_COMMAND" },
{ RAN_MSG_HANDOVER_SUCCEEDED, "HANDOVER_SUCCEEDED" },
{ RAN_MSG_HANDOVER_PERFORMED, "HANDOVER_PERFORMED" },
{ RAN_MSG_HANDOVER_REQUIRED, "HANDOVER_REQUIRED" },
{ RAN_MSG_HANDOVER_REQUIRED_REJECT, "HANDOVER_REQUIRED_REJECT" },
{ RAN_MSG_HANDOVER_REQUEST, "HANDOVER_REQUEST" },
{ RAN_MSG_HANDOVER_REQUEST_ACK, "HANDOVER_REQUEST_ACK" },
{ RAN_MSG_HANDOVER_DETECT, "HANDOVER_DETECT" },
{ RAN_MSG_HANDOVER_COMPLETE, "HANDOVER_COMPLETE" },
{ RAN_MSG_HANDOVER_FAILURE, "HANDOVER_FAILURE" },
{}
};
/* extract the N(SD) and return the modulo value for a R99 message */
static uint8_t ran_dec_dtap_undup_determine_nsd_ret_modulo_r99(uint8_t pdisc, uint8_t msg_type, uint8_t *n_sd)
{
switch (pdisc) {
case GSM48_PDISC_MM:
case GSM48_PDISC_CC:
case GSM48_PDISC_NC_SS:
*n_sd = (msg_type >> 6) & 0x3;
return 4;
case GSM48_PDISC_GROUP_CC:
case GSM48_PDISC_BCAST_CC:
case GSM48_PDISC_LOC:
*n_sd = (msg_type >> 6) & 0x1;
return 2;
default:
/* no sequence number, we cannot detect dups */
return 0;
}
}
/* extract the N(SD) and return the modulo value for a R98 message */
static uint8_t gsm0407_determine_nsd_ret_modulo_r98(uint8_t pdisc, uint8_t msg_type, uint8_t *n_sd)
{
switch (pdisc) {
case GSM48_PDISC_MM:
case GSM48_PDISC_CC:
case GSM48_PDISC_NC_SS:
case GSM48_PDISC_GROUP_CC:
case GSM48_PDISC_BCAST_CC:
case GSM48_PDISC_LOC:
*n_sd = (msg_type >> 6) & 0x1;
return 2;
default:
/* no sequence number, we cannot detect dups */
return 0;
}
}
/* TS 24.007 11.2.3.2.3 Message Type Octet / Duplicate Detection.
* (Not static for unit testing). */
int ran_dec_dtap_undup_pdisc_ctr_bin(uint8_t pdisc)
{
switch (pdisc) {
case GSM48_PDISC_MM:
case GSM48_PDISC_CC:
case GSM48_PDISC_NC_SS:
return 0;
case GSM48_PDISC_GROUP_CC:
return 1;
case GSM48_PDISC_BCAST_CC:
return 2;
case GSM48_PDISC_LOC:
return 3;
default:
return -1;
}
}
/* TS 24.007 11.2.3.2 Message Type Octet / Duplicate Detection */
bool ran_dec_dtap_undup_is_duplicate(struct osmo_fsm_inst *log_fi, uint8_t *n_sd_next, bool is_r99, struct msgb *l3)
{
struct gsm48_hdr *gh;
uint8_t pdisc;
uint8_t n_sd, modulo;
int bin;
gh = msgb_l3(l3);
pdisc = gsm48_hdr_pdisc(gh);
if (is_r99) {
modulo = ran_dec_dtap_undup_determine_nsd_ret_modulo_r99(pdisc, gh->msg_type, &n_sd);
} else { /* pre R99 */
modulo = gsm0407_determine_nsd_ret_modulo_r98(pdisc, gh->msg_type, &n_sd);
}
if (modulo == 0)
return false;
bin = ran_dec_dtap_undup_pdisc_ctr_bin(pdisc);
if (bin < 0)
return false;
OSMO_ASSERT(bin >= 0 && bin < 4);
if (n_sd != n_sd_next[bin]) {
/* not what we expected: duplicate */
LOGPFSML(log_fi, LOGL_NOTICE, "Duplicate DTAP: bin=%d, expected n_sd == %u, got %u\n",
bin, n_sd_next[bin], n_sd);
return true;
} else {
/* as expected: no dup; update expected counter for next message */
n_sd_next[bin] = (n_sd + 1) % modulo;
return false;
}
}
/* convenience: RAN decode implementations can call this to dispatch the decode_cb with a decoded ran_msg. */
int ran_decoded(struct ran_dec *ran_dec, struct ran_msg *ran_msg)
{
if (!ran_dec->decode_cb)
return -1;
return ran_dec->decode_cb(ran_dec->caller_fi, ran_dec->caller_data, ran_msg);
}
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