308 lines
7.8 KiB
C
308 lines
7.8 KiB
C
/* q931_decode.c - minimalistic Q.931 protocol decoder
|
|
*
|
|
* (C) 2022 by Harald Welte <laforge@osmocom.org>
|
|
*
|
|
* All Rights Reserved
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#include <errno.h>
|
|
|
|
#include <osmocom/gsm/tlv.h>
|
|
|
|
#include "q931.h"
|
|
#include "log.h"
|
|
|
|
/* Table 4-3/Q.931 */
|
|
const struct tlv_definition q931_tlv_def = {
|
|
.def = {
|
|
/* fixed-length */
|
|
[0x80] = { TLV_TYPE_SINGLE_TV, 0 },
|
|
[0x90] = { TLV_TYPE_SINGLE_TV, 0 },
|
|
[Q931_IEI_MORE_DATA] = { TLV_TYPE_T, 0 },
|
|
[Q931_IEI_SENDING_COMPLETE] = { TLV_TYPE_T, 0 },
|
|
[0xB0] = { TLV_TYPE_SINGLE_TV, 0 },
|
|
[0xD0] = { TLV_TYPE_SINGLE_TV, 0 },
|
|
/* variable-length */
|
|
[Q931_IEI_SEGMENTED_MSG] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_BEARER_CAP] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CAUSE] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CALL_ID] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CALL_STATE] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CHANNEL_ID] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_PROGRESS_IND] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_NETWORK_SPEC_FAC] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_NOTIFICATION_IND] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_DISPLAY] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_DATE_TIME] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_KEYPAD_FACILITY] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_SIGNAL] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_INFORMATION_RATE] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_E2E_TRANSIT_DELAY] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_TRANSIT_DELAY_SEL_AND_IND] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_PKT_LAYER_BIN_PARAMS] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_PKT_LAYER_WIN_SIZE] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_PACKET_SIZE] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CLOSED_USER_GROUP] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_REV_CHARGING_IND] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CALLING_PARTY_NUM] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CALLING_PARTY_SUBADDR]= { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CALLED_PARTY_NUM] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_CALLED_PARTY_SUBADDR] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_TRANSIT_NET_SEL] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_RESTART_IND] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_LOW_LAYER_COMPAT] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_HIGH_LAYER_COMPAT] = { TLV_TYPE_TLV, 0 },
|
|
[Q931_IEI_ESCAPE_FOR_EXT] = { TLV_TYPE_TLV, 0 },
|
|
},
|
|
};
|
|
|
|
/* parse one Q.931 message for signaling analysis */
|
|
int q931_msg_parse(struct q931_msg_parsed *out, const uint8_t *buf, size_t len)
|
|
{
|
|
uint8_t cref_len;
|
|
const uint8_t *other_ie;
|
|
size_t other_ie_len;
|
|
int rc;
|
|
|
|
memset(out, 0, sizeof(*out));
|
|
|
|
/* at least protocol discriminator + length of call-ref must be present */
|
|
if (len < 2) {
|
|
LOGP(DQ931, LOGL_ERROR, "short Q.931 message: %s\n", osmo_hexdump(buf, len));
|
|
return -EMSGSIZE;
|
|
}
|
|
|
|
/* check protocol discriminator */
|
|
if (buf[0] != 0x08) {
|
|
LOGP(DQ931, LOGL_ERROR, "unknoqn Q.931 protocol discrimnator 0x%02x: %s", buf[0],
|
|
osmo_hexdump(buf, len));
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* parse [variable length] call reference */
|
|
cref_len = buf[1] & 0x0F;
|
|
if (len < 2U + cref_len) {
|
|
LOGP(DQ931, LOGL_ERROR, "short Q.931 message: %s\n", osmo_hexdump(buf, len));
|
|
return -EMSGSIZE;
|
|
}
|
|
out->call_ref = q931_decode_callref(buf+1, 1+cref_len);
|
|
|
|
/* parse message type */
|
|
if (len < 2U + cref_len + 1U) {
|
|
LOGP(DQ931, LOGL_ERROR, "short Q.931 message: %s\n", osmo_hexdump(buf, len));
|
|
return -EMSGSIZE;
|
|
}
|
|
out->msg_type = buf[2+cref_len] & 0x7f;
|
|
|
|
/* parse 'other IEs' */
|
|
other_ie = buf + 2 + cref_len + 1;
|
|
other_ie_len = len - (2 + cref_len + 1);
|
|
if (other_ie_len) {
|
|
rc = tlv_parse(&out->ies, &q931_tlv_def, other_ie, other_ie_len, 0, 0);
|
|
if (rc < 0) {
|
|
LOGP(DQ931, LOGL_ERROR, "Can't TLV-parse Q.931 message: %s\n", osmo_hexdump(buf, len));
|
|
return rc;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Q.931 Section 4.3 */
|
|
uint32_t q931_decode_callref(const uint8_t *data, uint8_t len)
|
|
{
|
|
uint8_t len_of_callref;
|
|
uint32_t callref = 0;
|
|
bool flag = false;
|
|
|
|
if (len < 1)
|
|
goto err;
|
|
|
|
len_of_callref = data[0] & 0x0f;
|
|
if (len_of_callref == 0)
|
|
goto err;
|
|
|
|
if (len_of_callref > 4)
|
|
goto err;
|
|
|
|
if (len - 1 < len_of_callref)
|
|
goto err;
|
|
|
|
/* first octet contains flag, needs special handling */
|
|
if (data[1] & 0x80)
|
|
flag = true;
|
|
callref = data[1] & 0x7f;
|
|
|
|
/* all further octets ... */
|
|
for (unsigned i = 1; i < len_of_callref; i++)
|
|
callref = (callref << 8) | data[1+i];
|
|
|
|
if (flag)
|
|
callref |= 0x80000000;
|
|
|
|
return callref;
|
|
err:
|
|
LOGP(DQ931, LOGL_ERROR, "Unable to decode Q.931 call reference: %s\n",
|
|
osmo_hexdump(data, len));
|
|
return 0;
|
|
}
|
|
|
|
/* Decode a (subset of) Q.931 channel identification IE from binary to struct representation */
|
|
int q931_decode_channel_id(struct q931_channel_id *out, const uint8_t *data, uint8_t len)
|
|
{
|
|
const uint8_t *cur = data;
|
|
|
|
memset(out, 0, sizeof(*out));
|
|
|
|
if (len < 1)
|
|
goto err;
|
|
|
|
if (! (data[0] & 0x80))
|
|
goto err;
|
|
|
|
if (data[0] & 0x40) {
|
|
out->interface_id_present = true;
|
|
cur++;
|
|
if (len < 1 + (cur - data))
|
|
goto err;
|
|
/* we only support single-octet interface ID */
|
|
if (!(*cur & 0x80))
|
|
goto err;
|
|
out->interface_id = *cur & 0x7f;
|
|
}
|
|
|
|
if (data[0] & 0x20)
|
|
out->interface_type_pri = true;
|
|
|
|
if (data[0] & 0x08)
|
|
out->exclusive = true;
|
|
|
|
if (data[0] & 0x04) {
|
|
out->d_channel = true;
|
|
} else {
|
|
switch (data[0] & 0x03) {
|
|
case 0:
|
|
out->info_chan_type = Q931_INFO_CHAN_T_NONE;
|
|
break;
|
|
case 1:
|
|
if (out->interface_type_pri == false) {
|
|
out->b_channel = 1;
|
|
} else {
|
|
/* Octet 3.2 */
|
|
cur++;
|
|
if (len < 1 + (cur - data))
|
|
goto err;
|
|
if (!(*cur & 0x80))
|
|
goto err;
|
|
/* do we care about the coding standard? */
|
|
/* we only support single channel numbers */
|
|
if (*cur & 0x10)
|
|
goto err;
|
|
/* we only support B-channels */
|
|
if ((*cur & 0x0f) != 0x03)
|
|
goto err;
|
|
/* Octet 3.3 */
|
|
cur++;
|
|
if (len < 1 + (cur - data))
|
|
goto err;
|
|
/* we only support single channel numbers */
|
|
if (!(*cur & 0x80))
|
|
goto err;
|
|
out->b_channel = *cur & 0x7f;
|
|
}
|
|
break;
|
|
case 2:
|
|
if (out->interface_type_pri == false)
|
|
out->b_channel = 2;
|
|
else
|
|
goto err;
|
|
break;
|
|
case 3:
|
|
out->info_chan_type = Q931_INFO_CHAN_T_ANY;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
err:
|
|
LOGP(DQ931, LOGL_ERROR, "Unable to decode Q.931 channel id: %s\n",
|
|
osmo_hexdump(data, len));
|
|
return -1;
|
|
|
|
}
|
|
|
|
/* Q.931 Section 4.5.8 */
|
|
int q931_decode_called_party(struct q931_party_number *out, const uint8_t *buf, size_t len)
|
|
{
|
|
memset(out, 0, sizeof(*out));
|
|
|
|
if (len < 1)
|
|
goto err;
|
|
|
|
/* Octet 3 */
|
|
if (!(*buf & 0x80))
|
|
goto err;
|
|
out->type_of_number = (*buf >> 4) & 0x7;
|
|
out->numbering_plan_id = *buf & 0xf;
|
|
|
|
for (unsigned int i = 0; i < len - 1; i++) {
|
|
if (i >= sizeof(out->digits))
|
|
goto err;
|
|
out->digits[i] = buf[1+i] & 0x7f;
|
|
}
|
|
return 0;
|
|
err:
|
|
LOGP(DQ931, LOGL_ERROR, "Unable to decode Q.931 called party: %s\n",
|
|
osmo_hexdump(buf, len));
|
|
return -1;
|
|
}
|
|
|
|
/* Q.931 Section 4.5.10 */
|
|
int q931_decode_calling_party(struct q931_party_number *out, const uint8_t *buf, size_t len)
|
|
{
|
|
const uint8_t *cur = buf;
|
|
|
|
memset(out, 0, sizeof(*out));
|
|
|
|
if (len < 1)
|
|
goto err;
|
|
|
|
/* Octet 3 */
|
|
out->type_of_number = (*cur >> 4) & 0x7;
|
|
out->numbering_plan_id = *cur & 0xf;
|
|
if (!(*cur & 0x80)) {
|
|
/* Octet 3a */
|
|
cur++;
|
|
if (len < 2)
|
|
goto err;
|
|
if (!(*cur & 0x80))
|
|
goto err;
|
|
out->presentation_ind = (*cur >> 5) & 0x3;
|
|
out->screening_ind = *cur & 0x3;
|
|
}
|
|
cur++;
|
|
|
|
for (unsigned int i = 0; i < len - (cur - buf); i++) {
|
|
if (i >= sizeof(out->digits))
|
|
goto err;
|
|
out->digits[i] = cur[i] & 0x7f;
|
|
}
|
|
return 0;
|
|
err:
|
|
LOGP(DQ931, LOGL_ERROR, "Unable to decode Q.931 calling party: %s\n",
|
|
osmo_hexdump(buf, len));
|
|
return -1;
|
|
}
|