Neels Hofmeyr | c6848f4 | 2020-09-18 18:00:50 +0200 | [diff] [blame] | 1 | /* 3GPP TS 48.071 BSSLAP protocol definitions */ |
| 2 | /* |
| 3 | * (C) 2020 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de> |
| 4 | * All Rights Reserved |
| 5 | * |
| 6 | * Author: Neels Hofmeyr <neels@hofmeyr.de> |
| 7 | * |
| 8 | * SPDX-License-Identifier: GPL-2.0+ |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify |
| 11 | * it under the terms of the GNU General Public License as published by |
| 12 | * the Free Software Foundation; either version 2 of the License, or |
| 13 | * (at your option) any later version. |
| 14 | * |
| 15 | * This program is distributed in the hope that it will be useful, |
| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | * GNU General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU General Public License along |
| 21 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 22 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 23 | * |
| 24 | */ |
| 25 | |
| 26 | #include <errno.h> |
| 27 | |
| 28 | #include <osmocom/core/msgb.h> |
| 29 | #include <osmocom/gsm/bsslap.h> |
| 30 | #include <osmocom/gsm/tlv.h> |
| 31 | |
| 32 | #include <osmocom/core/logging.h> |
| 33 | |
| 34 | /*! \addtogroup bsslap |
| 35 | * @{ |
| 36 | * \file bsslap.c |
| 37 | * Message encoding and decoding for 3GPP TS 48.071 BSSLAP protocol. |
| 38 | */ |
| 39 | |
| 40 | static const struct tlv_definition osmo_bsslap_tlvdef = { |
| 41 | .def = { |
| 42 | [BSSLAP_IEI_TA] = { TLV_TYPE_TV }, |
| 43 | [BSSLAP_IEI_CELL_ID] = { TLV_TYPE_FIXED, 2 }, |
| 44 | [BSSLAP_IEI_CHAN_DESC] = { TLV_TYPE_FIXED, 3 }, |
| 45 | [BSSLAP_IEI_MEAS_REP] = { TLV_TYPE_TLV }, |
| 46 | [BSSLAP_IEI_CAUSE] = { TLV_TYPE_TV }, |
| 47 | [BSSLAP_IEI_RRLP_FLAG] = { TLV_TYPE_TV }, |
| 48 | [BSSLAP_IEI_RRLP] = { TLV_TYPE_TLV }, |
| 49 | [BSSLAP_IEI_CELL_ID_LIST] = { TLV_TYPE_TLV }, |
| 50 | [BSSLAP_IEI_ENH_MEAS_REP] = { TLV_TYPE_TLV }, |
| 51 | [BSSLAP_IEI_LAC] = { TLV_TYPE_TLV }, |
| 52 | [BSSLAP_IEI_FREQ_LIST] = { TLV_TYPE_TLV }, |
| 53 | [BSSLAP_IEI_MS_POWER] = { TLV_TYPE_TV }, |
| 54 | [BSSLAP_IEI_DELTA_TIMER] = { TLV_TYPE_TV }, |
| 55 | [BSSLAP_IEI_SERVING_CELL_ID] = { TLV_TYPE_TLV }, |
| 56 | [BSSLAP_IEI_ENCR_KEY] = { TLV_TYPE_FIXED, 8 }, |
| 57 | [BSSLAP_IEI_CIPH_MODE_SET] = { TLV_TYPE_TV }, |
| 58 | [BSSLAP_IEI_CHAN_MODE] = { TLV_TYPE_TV, 2 }, |
| 59 | [BSSLAP_IEI_MR_CONFIG] = { TLV_TYPE_TLV }, |
| 60 | [BSSLAP_IEI_POLLING_REPETITION] = { TLV_TYPE_TV }, |
| 61 | [BSSLAP_IEI_PACKET_CHAN_DESC] = { TLV_TYPE_FIXED, 4 }, |
| 62 | [BSSLAP_IEI_TLLI] = { TLV_TYPE_FIXED, 4 }, |
| 63 | [BSSLAP_IEI_TFI] = { TLV_TYPE_TLV }, |
| 64 | [BSSLAP_IEI_TBF_START_TIME] = { TLV_TYPE_FIXED, 2 }, |
| 65 | [BSSLAP_IEI_PWRUP_START_TIME] = { TLV_TYPE_TLV }, |
| 66 | [BSSLAP_IEI_LONG_ENCR_KEY] = { TLV_TYPE_FIXED, 16 }, |
| 67 | [BSSLAP_IEI_CONCUR_POS_PROC_F] = { TLV_TYPE_TV }, |
| 68 | }, |
| 69 | }; |
| 70 | |
| 71 | #define DEC_ERR(RC, MSG_TYPE, IEI, CAUSE, fmt, args...) do { \ |
| 72 | if (err && !*err) { \ |
| 73 | *err = talloc_zero(err_ctx, struct osmo_bsslap_err); \ |
| 74 | **err = (struct osmo_bsslap_err){ \ |
| 75 | .rc = (RC), \ |
| 76 | .msg_type = (MSG_TYPE), \ |
| 77 | .iei = (IEI), \ |
| 78 | .cause = (CAUSE), \ |
| 79 | .logmsg = talloc_asprintf(*err, "Error decoding BSSLAP%s%s%s%s%s: " fmt, \ |
| 80 | (MSG_TYPE) >= 0 ? " " : "", \ |
| 81 | (MSG_TYPE) >= 0 ? osmo_bsslap_msgt_name(MSG_TYPE) : "", \ |
| 82 | (IEI) >= 0 ? ": " : "", \ |
| 83 | (IEI) >= 0 ? osmo_bsslap_iei_name(IEI) : "", \ |
| 84 | (IEI) >= 0 ? " IE" : "", \ |
| 85 | ##args), \ |
| 86 | }; \ |
| 87 | } \ |
| 88 | return RC; \ |
| 89 | } while(0) |
| 90 | |
| 91 | static void osmo_bsslap_ie_enc_cell_id(struct msgb *msg, uint16_t cell_id) |
| 92 | { |
| 93 | msgb_put_u8(msg, BSSLAP_IEI_CELL_ID); |
| 94 | msgb_put_u16(msg, cell_id); |
| 95 | } |
| 96 | |
| 97 | static int osmo_bsslap_ie_dec_cell_id(uint16_t *cell_id, |
| 98 | enum bsslap_msgt msgt, enum bsslap_iei iei, |
| 99 | struct osmo_bsslap_err **err, void *err_ctx, |
| 100 | const uint8_t *data, size_t len) |
| 101 | { |
| 102 | if (len != 2) |
| 103 | DEC_ERR(-EINVAL, msgt, iei, LCS_CAUSE_UNSPECIFIED, "Expected 2 bytes, got %zu", len); |
| 104 | *cell_id = osmo_load16be(data); |
| 105 | return 0; |
| 106 | } |
| 107 | |
| 108 | static void osmo_bsslap_ie_enc_ta(struct msgb *msg, uint8_t ta) |
| 109 | { |
| 110 | msgb_put_u8(msg, BSSLAP_IEI_TA); |
| 111 | msgb_put_u8(msg, ta); |
| 112 | } |
| 113 | |
| 114 | static int osmo_bsslap_ie_dec_ta(uint8_t *ta, |
| 115 | enum bsslap_msgt msgt, enum bsslap_iei iei, |
| 116 | struct osmo_bsslap_err **err, void *err_ctx, |
| 117 | const uint8_t *data, size_t len) |
| 118 | { |
| 119 | if (len != 1) |
| 120 | DEC_ERR(-EINVAL, msgt, iei, LCS_CAUSE_UNSPECIFIED, "Expected 1 byte, got %zu", len); |
| 121 | *ta = data[0]; |
| 122 | return 0; |
| 123 | } |
| 124 | |
| 125 | static void osmo_bsslap_ie_enc_cause(struct msgb *msg, enum bsslap_cause cause) |
| 126 | { |
| 127 | msgb_put_u8(msg, BSSLAP_IEI_CAUSE); |
| 128 | msgb_put_u8(msg, cause); |
| 129 | } |
| 130 | |
| 131 | static int osmo_bsslap_ie_dec_cause(enum bsslap_cause *cause, |
| 132 | enum bsslap_msgt msgt, enum bsslap_iei iei, |
| 133 | struct osmo_bsslap_err **err, void *err_ctx, |
| 134 | const uint8_t *data, size_t len) |
| 135 | { |
| 136 | if (len != 1) |
| 137 | DEC_ERR(-EINVAL, msgt, iei, LCS_CAUSE_UNSPECIFIED, "Expected 1 byte, got %zu", len); |
| 138 | *cause = data[0]; |
| 139 | return 0; |
| 140 | } |
| 141 | |
| 142 | static void osmo_bsslap_ie_enc_chan_desc(struct msgb *msg, const struct gsm48_chan_desc *chan_desc) |
| 143 | { |
| 144 | struct gsm48_chan_desc *put_chan_desc; |
| 145 | msgb_put_u8(msg, BSSLAP_IEI_CHAN_DESC); |
| 146 | put_chan_desc = (void*)msgb_put(msg, sizeof(*chan_desc)); |
| 147 | *put_chan_desc = *chan_desc; |
| 148 | } |
| 149 | |
| 150 | static int osmo_bsslap_ie_dec_chan_desc(struct gsm48_chan_desc *chan_desc, |
| 151 | enum bsslap_msgt msgt, enum bsslap_iei iei, |
| 152 | struct osmo_bsslap_err **err, void *err_ctx, |
| 153 | const uint8_t *data, size_t len) |
| 154 | { |
| 155 | if (len != sizeof(*chan_desc)) |
| 156 | DEC_ERR(-EINVAL, msgt, iei, LCS_CAUSE_UNSPECIFIED, "Expected %zu bytes, got %zu", |
| 157 | sizeof(*chan_desc), len); |
| 158 | *chan_desc = *(struct gsm48_chan_desc*)data; |
| 159 | return 0; |
| 160 | } |
| 161 | |
| 162 | /*! Encode BSSLAP PDU and append to msgb (3GPP TS 48.071). |
| 163 | * \param[out] msg msgb to append to. |
| 164 | * \param[in] pdu PDU data to encode. |
| 165 | * \return number of bytes written, negative on error. |
| 166 | */ |
| 167 | int osmo_bsslap_enc(struct msgb *msg, const struct bsslap_pdu *pdu) |
| 168 | { |
| 169 | uint8_t *old_tail = msg->tail; |
| 170 | |
| 171 | msgb_put_u8(msg, pdu->msg_type); |
| 172 | |
| 173 | switch (pdu->msg_type) { |
| 174 | case BSSLAP_MSGT_TA_REQUEST: |
| 175 | /* The TA Request message contains only the message type. */ |
| 176 | break; |
| 177 | |
| 178 | case BSSLAP_MSGT_TA_RESPONSE: |
| 179 | osmo_bsslap_ie_enc_cell_id(msg, pdu->ta_response.cell_id); |
| 180 | osmo_bsslap_ie_enc_ta(msg, pdu->ta_response.ta); |
| 181 | break; |
| 182 | |
| 183 | case BSSLAP_MSGT_REJECT: |
| 184 | osmo_bsslap_ie_enc_cause(msg, pdu->reject); |
| 185 | break; |
| 186 | |
| 187 | case BSSLAP_MSGT_RESET: |
| 188 | osmo_bsslap_ie_enc_cell_id(msg, pdu->reset.cell_id); |
| 189 | osmo_bsslap_ie_enc_ta(msg, pdu->reset.ta); |
| 190 | osmo_bsslap_ie_enc_chan_desc(msg, &pdu->reset.chan_desc); |
| 191 | osmo_bsslap_ie_enc_cause(msg, pdu->reset.cause); |
| 192 | break; |
| 193 | |
| 194 | case BSSLAP_MSGT_ABORT: |
| 195 | osmo_bsslap_ie_enc_cause(msg, pdu->abort); |
| 196 | break; |
| 197 | |
| 198 | case BSSLAP_MSGT_TA_LAYER3: |
| 199 | osmo_bsslap_ie_enc_ta(msg, pdu->ta_layer3.ta); |
| 200 | break; |
| 201 | |
| 202 | default: |
| 203 | return -ENOTSUP; |
| 204 | } |
| 205 | return (msg->tail - old_tail); |
| 206 | } |
| 207 | |
| 208 | /*! Decode BSSLAP PDU (3GPP TS 48.071). |
| 209 | * \param[out] pdu Write decoded values here. |
| 210 | * \param[out] err Returned pointer to error info, dynamically allocated; NULL to not return any. |
| 211 | * \param[in] err_ctx Talloc context to allocate err from, if required. |
| 212 | * \param[in] data Pointer to BSSLAP PDU raw data. |
| 213 | * \param[in] len Data length to decode. |
| 214 | * \return 0 on success, negative on error. |
| 215 | */ |
| 216 | int osmo_bsslap_dec(struct bsslap_pdu *pdu, |
| 217 | struct osmo_bsslap_err **err, void *err_ctx, |
| 218 | const uint8_t *data, size_t len) |
| 219 | { |
| 220 | const uint8_t *ies_start; |
| 221 | int ies_len; |
| 222 | struct tlv_parsed tp; |
| 223 | |
| 224 | *pdu = (struct bsslap_pdu){}; |
| 225 | if (err) |
| 226 | *err = NULL; |
| 227 | |
| 228 | #define DEC_IE_MANDATORY(IEI, DEC_FUN, DEC_FUN_ARG) do { \ |
| 229 | const struct tlv_p_entry *e; \ |
| 230 | int rc; \ |
| 231 | if (!(e = TLVP_GET(&tp, IEI))) \ |
| 232 | DEC_ERR(-EINVAL, pdu->msg_type, IEI, LCS_CAUSE_DATA_MISSING_IN_REQ, "missing mandatory IE"); \ |
| 233 | rc = DEC_FUN(DEC_FUN_ARG, pdu->msg_type, IEI, err, err_ctx, e->val, e->len); \ |
| 234 | if (rc) \ |
| 235 | DEC_ERR(rc, pdu->msg_type, IEI, LCS_CAUSE_UNSPECIFIED, "cannot parse IE"); \ |
| 236 | } while (0) |
| 237 | |
| 238 | if (len < 1) |
| 239 | DEC_ERR(-EINVAL, -1, -1, LCS_CAUSE_UNSPECIFIED, "PDU too short: %zu b", len); |
| 240 | |
| 241 | pdu->msg_type = data[0]; |
| 242 | |
| 243 | if (pdu->msg_type == BSSLAP_MSGT_TA_REQUEST) { |
| 244 | /* The TA Request message contains only the message type. */ |
| 245 | return 0; |
| 246 | } |
| 247 | |
| 248 | ies_start = &data[1]; |
| 249 | ies_len = len - 1; |
| 250 | |
| 251 | if (tlv_parse2(&tp, 1, &osmo_bsslap_tlvdef, ies_start, ies_len, 0, 0) <= 0) |
| 252 | DEC_ERR(-EINVAL, pdu->msg_type, -1, LCS_CAUSE_UNSPECIFIED, "failed to parse TLV structure"); |
| 253 | |
| 254 | switch (pdu->msg_type) { |
| 255 | |
| 256 | case BSSLAP_MSGT_TA_RESPONSE: |
| 257 | DEC_IE_MANDATORY(BSSLAP_IEI_CELL_ID, osmo_bsslap_ie_dec_cell_id, &pdu->ta_response.cell_id); |
| 258 | DEC_IE_MANDATORY(BSSLAP_IEI_TA, osmo_bsslap_ie_dec_ta, &pdu->ta_response.ta); |
| 259 | return 0; |
| 260 | |
| 261 | case BSSLAP_MSGT_REJECT: |
| 262 | DEC_IE_MANDATORY(BSSLAP_IEI_CAUSE, osmo_bsslap_ie_dec_cause, &pdu->reject); |
| 263 | return 0; |
| 264 | |
| 265 | case BSSLAP_MSGT_RESET: |
| 266 | DEC_IE_MANDATORY(BSSLAP_IEI_CELL_ID, osmo_bsslap_ie_dec_cell_id, &pdu->reset.cell_id); |
| 267 | DEC_IE_MANDATORY(BSSLAP_IEI_TA, osmo_bsslap_ie_dec_ta, &pdu->reset.ta); |
| 268 | DEC_IE_MANDATORY(BSSLAP_IEI_CHAN_DESC, osmo_bsslap_ie_dec_chan_desc, &pdu->reset.chan_desc); |
| 269 | DEC_IE_MANDATORY(BSSLAP_IEI_CAUSE, osmo_bsslap_ie_dec_cause, &pdu->reset.cause); |
| 270 | return 0; |
| 271 | |
| 272 | case BSSLAP_MSGT_ABORT: |
| 273 | DEC_IE_MANDATORY(BSSLAP_IEI_CAUSE, osmo_bsslap_ie_dec_cause, &pdu->abort); |
| 274 | return 0; |
| 275 | |
| 276 | case BSSLAP_MSGT_TA_LAYER3: |
| 277 | DEC_IE_MANDATORY(BSSLAP_IEI_TA, osmo_bsslap_ie_dec_ta, &pdu->ta_layer3.ta); |
| 278 | return 0; |
| 279 | |
| 280 | default: |
| 281 | DEC_ERR(-EINVAL, pdu->msg_type, -1, LCS_CAUSE_UNSPECIFIED, "Unsupported message type"); |
| 282 | } |
| 283 | } |
| 284 | |
| 285 | const struct value_string osmo_bsslap_msgt_names[] = { |
| 286 | { BSSLAP_MSGT_TA_REQUEST, "TA Request" }, |
| 287 | { BSSLAP_MSGT_TA_RESPONSE, "TA Response" }, |
| 288 | { BSSLAP_MSGT_REJECT, "Reject" }, |
| 289 | { BSSLAP_MSGT_RESET, "Reset" }, |
| 290 | { BSSLAP_MSGT_ABORT, "Abort" }, |
| 291 | { BSSLAP_MSGT_TA_LAYER3, "TA Layer3" }, |
| 292 | { BSSLAP_MSGT_MS_POS_CMD, "MS Position Command" }, |
| 293 | { BSSLAP_MSGT_MS_POS_RESP, "MS Position Response" }, |
| 294 | { BSSLAP_MSGT_UTDOA_REQ, "U-TDOA Request" }, |
| 295 | { BSSLAP_MSGT_UTDOA_RESP, "U-TDOA Response" }, |
| 296 | {} |
| 297 | }; |
| 298 | |
| 299 | const struct value_string osmo_bsslap_iei_names[] = { |
| 300 | { BSSLAP_IEI_TA, "Timing Advance" }, |
| 301 | { BSSLAP_IEI_CELL_ID, "Cell Identity" }, |
| 302 | { BSSLAP_IEI_CHAN_DESC, "Channel Description" }, |
| 303 | { BSSLAP_IEI_MEAS_REP, "Measurement Report" }, |
| 304 | { BSSLAP_IEI_CAUSE, "Cause" }, |
| 305 | { BSSLAP_IEI_RRLP_FLAG, "RRLP Flag" }, |
| 306 | { BSSLAP_IEI_RRLP, "RRLP" }, |
| 307 | { BSSLAP_IEI_CELL_ID_LIST, "Cell Identity List" }, |
| 308 | { BSSLAP_IEI_ENH_MEAS_REP, "Enhanced Measurement Report" }, |
| 309 | { BSSLAP_IEI_LAC, "Location Area Code" }, |
| 310 | { BSSLAP_IEI_FREQ_LIST, "Frequency List" }, |
| 311 | { BSSLAP_IEI_MS_POWER, "MS Power" }, |
| 312 | { BSSLAP_IEI_DELTA_TIMER, "Delta Timer" }, |
| 313 | { BSSLAP_IEI_SERVING_CELL_ID, "Serving Cell Identifier" }, |
| 314 | { BSSLAP_IEI_ENCR_KEY, "Encryption Key" }, |
| 315 | { BSSLAP_IEI_CIPH_MODE_SET, "Cipher Mode Setting" }, |
| 316 | { BSSLAP_IEI_CHAN_MODE, "Channel Mode" }, |
| 317 | { BSSLAP_IEI_MR_CONFIG, "MultiRate Configuration" }, |
| 318 | { BSSLAP_IEI_POLLING_REPETITION, "Polling Repetition" }, |
| 319 | { BSSLAP_IEI_PACKET_CHAN_DESC, "Packet Channel Description" }, |
| 320 | { BSSLAP_IEI_TLLI, "TLLI" }, |
| 321 | { BSSLAP_IEI_TFI, "TFI" }, |
| 322 | { BSSLAP_IEI_TBF_START_TIME, "TBF Starting Time" }, |
| 323 | { BSSLAP_IEI_PWRUP_START_TIME, "Powerup Starting Time" }, |
| 324 | { BSSLAP_IEI_LONG_ENCR_KEY, "Long Encryption Key" }, |
| 325 | { BSSLAP_IEI_CONCUR_POS_PROC_F, "Concurrent Positioning Flag" }, |
| 326 | {} |
| 327 | }; |
| 328 | |
| 329 | /*! @} */ |