mirror of https://gerrit.osmocom.org/libosmocore
193 lines
5.5 KiB
C
193 lines
5.5 KiB
C
/*
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* (C) 2015-2016 by sysmocom - s.f.m.c. GmbH
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* Author: Neels Hofmeyr
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* All Rights Reserved
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*
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* SPDX-License-Identifier: GPL-2.0+
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include <osmocom/core/utils.h>
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#include <osmocom/core/logging.h>
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#include <osmocom/core/msgb.h>
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#include <osmocom/gsm/tlv.h>
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#include <osmocom/gsm/oap.h>
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#include <stdint.h>
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/*! \addtogroup oap
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* @{
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* \file oap.c
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* Osmocom Authentication Protocol
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*/
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/*! Decode OAP message data.
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* \param[out] oap_msg Parsed data is written to this instance.
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* \param[in] data Pointer to the data buffer containing the OAP message.
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* \param[in] data_len Length of the OAP message data.
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* \returns 0 on success, a negative cause value on failure.
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*/
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int osmo_oap_decode(struct osmo_oap_message *oap_msg,
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const uint8_t *const_data, size_t data_len)
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{
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int rc;
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uint8_t tag;
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/* the shift/match functions expect non-const pointers, but we'll
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* either copy the data or cast pointers back to const before returning
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* them
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*/
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uint8_t *data = (uint8_t *)const_data;
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uint8_t *value;
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size_t value_len;
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memset(oap_msg, 0, sizeof(*oap_msg));
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/* message type */
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rc = osmo_shift_v_fixed(&data, &data_len, 1, &value);
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if (rc < 0)
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return -GMM_CAUSE_INV_MAND_INFO;
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oap_msg->message_type = osmo_decode_big_endian(value, 1);
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/* specific parts */
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while (data_len > 0) {
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enum osmo_oap_iei iei;
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rc = osmo_shift_tlv(&data, &data_len, &tag, &value, &value_len);
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if (rc < 0)
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return -GMM_CAUSE_PROTO_ERR_UNSPEC;
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iei = tag;
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switch (iei) {
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case OAP_CLIENT_ID_IE:
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if (value_len != 2) {
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LOGP(DLOAP, LOGL_NOTICE,
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"OAP IE type client ID (%d) should be 2 octets, but has %d\n",
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(int)iei, (int)value_len);
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return -GMM_CAUSE_PROTO_ERR_UNSPEC;
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}
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oap_msg->client_id = osmo_decode_big_endian(value, value_len);
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if (oap_msg->client_id == 0) {
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LOGP(DLOAP, LOGL_NOTICE,
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"OAP IE type client ID (%d): client ID must be nonzero.\n",
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(int)iei);
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return -GMM_CAUSE_PROTO_ERR_UNSPEC;
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}
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break;
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case OAP_AUTN_IE:
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if (value_len != sizeof(oap_msg->autn)) {
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LOGP(DLOAP, LOGL_NOTICE,
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"OAP IE type AUTN (%d) should be %d octets, but has %d\n",
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(int)iei, (int)sizeof(oap_msg->autn), (int)value_len);
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return -GMM_CAUSE_PROTO_ERR_UNSPEC;
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}
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memcpy(oap_msg->autn, value, value_len);
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oap_msg->autn_present = value_len ? 1 : 0;
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break;
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case OAP_RAND_IE:
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if (value_len != sizeof(oap_msg->rand)) {
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LOGP(DLOAP, LOGL_NOTICE,
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"OAP IE type RAND (%d) should be %d octets, but has %d\n",
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(int)iei, (int)sizeof(oap_msg->rand), (int)value_len);
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return -GMM_CAUSE_PROTO_ERR_UNSPEC;
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}
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memcpy(oap_msg->rand, value, value_len);
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oap_msg->rand_present = value_len ? 1 : 0;
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break;
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case OAP_XRES_IE:
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if (value_len != sizeof(oap_msg->xres)) {
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LOGP(DLOAP, LOGL_NOTICE,
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"OAP IE type XRES (%d) should be %d octets, but has %d\n",
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(int)iei, (int)sizeof(oap_msg->xres), (int)value_len);
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return -GMM_CAUSE_PROTO_ERR_UNSPEC;
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}
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memcpy(oap_msg->xres, value, value_len);
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oap_msg->xres_present = value_len ? 1 : 0;
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break;
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case OAP_AUTS_IE:
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if (value_len != sizeof(oap_msg->auts)) {
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LOGP(DLOAP, LOGL_NOTICE,
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"OAP IE type AUTS (%d) should be %d octets, but has %d\n",
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(int)iei, (int)sizeof(oap_msg->auts), (int)value_len);
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return -GMM_CAUSE_PROTO_ERR_UNSPEC;
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}
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memcpy(oap_msg->auts, value, value_len);
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oap_msg->auts_present = value_len ? 1 : 0;
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break;
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case OAP_CAUSE_IE:
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if (value_len > 1) {
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LOGP(DLOAP, LOGL_ERROR,
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"OAP cause may not exceed one octet, is %d", (int)value_len);
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return -GMM_CAUSE_PROTO_ERR_UNSPEC;
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}
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oap_msg->cause = *value;
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break;
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default:
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LOGP(DLOAP, LOGL_NOTICE,
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"OAP IE type %d unknown\n", iei);
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continue;
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}
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}
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return 0;
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}
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/*! Compose OAP message data.
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* \param[out] msg OAP message data is appended to this message buffer.
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* \param[in] oap_msg Elements to encode in the message data.
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*/
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void osmo_oap_encode(struct msgb *msg, const struct osmo_oap_message *oap_msg)
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{
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uint8_t u8;
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/* generic part */
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OSMO_ASSERT(oap_msg->message_type);
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msgb_v_put(msg, (uint8_t)oap_msg->message_type);
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/* specific parts */
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if ((u8 = oap_msg->cause))
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msgb_tlv_put(msg, OAP_CAUSE_IE, sizeof(u8), &u8);
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if (oap_msg->client_id > 0)
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msgb_tlv_put(msg, OAP_CLIENT_ID_IE, sizeof(oap_msg->client_id),
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osmo_encode_big_endian(oap_msg->client_id,
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sizeof(oap_msg->client_id)));
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if (oap_msg->rand_present)
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msgb_tlv_put(msg, OAP_RAND_IE, sizeof(oap_msg->rand), oap_msg->rand);
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if (oap_msg->autn_present)
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msgb_tlv_put(msg, OAP_AUTN_IE, sizeof(oap_msg->autn), oap_msg->autn);
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if (oap_msg->auts_present)
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msgb_tlv_put(msg, OAP_AUTS_IE, sizeof(oap_msg->auts), oap_msg->auts);
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if (oap_msg->xres_present)
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msgb_tlv_put(msg, OAP_XRES_IE, sizeof(oap_msg->xres), oap_msg->xres);
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msg->l2h = msg->data;
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}
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/*! @} */
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