Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 1 | /* GPRS Subscriber Update Protocol message encoder/decoder */ |
| 2 | |
| 3 | /* |
| 4 | * (C) 2014 by Sysmocom s.f.m.c. GmbH |
| 5 | * All Rights Reserved |
| 6 | * |
| 7 | * Author: Jacob Erlbeck |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU Affero General Public License as published by |
| 11 | * the Free Software Foundation; either version 3 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This program is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | * GNU Affero General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Affero General Public License |
| 20 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 21 | * |
| 22 | */ |
| 23 | |
| 24 | #include <openbsc/gprs_gsup_messages.h> |
| 25 | |
| 26 | #include <openbsc/debug.h> |
| 27 | #include <openbsc/gprs_utils.h> |
| 28 | |
| 29 | #include <osmocom/gsm/tlv.h> |
| 30 | #include <osmocom/core/msgb.h> |
| 31 | |
| 32 | #include <stdint.h> |
| 33 | |
| 34 | |
| 35 | static uint64_t decode_big_endian(const uint8_t *data, size_t data_len) |
| 36 | { |
| 37 | uint64_t value = 0; |
| 38 | |
| 39 | while (data_len > 0) { |
| 40 | value = (value << 8) + *data; |
| 41 | data += 1; |
| 42 | data_len -= 1; |
| 43 | } |
| 44 | |
| 45 | return value; |
| 46 | } |
| 47 | |
| 48 | static uint8_t *encode_big_endian(uint64_t value, size_t data_len) |
| 49 | { |
| 50 | static uint8_t buf[sizeof(uint64_t)]; |
| 51 | int idx; |
| 52 | |
| 53 | OSMO_ASSERT(data_len <= ARRAY_SIZE(buf)); |
| 54 | |
| 55 | for (idx = data_len - 1; idx >= 0; idx--) { |
| 56 | buf[idx] = (uint8_t)value; |
| 57 | value = value >> 8; |
| 58 | } |
| 59 | |
| 60 | return buf; |
| 61 | } |
| 62 | |
| 63 | static int decode_pdp_info(uint8_t *data, size_t data_len, |
| 64 | struct gprs_gsup_pdp_info *pdp_info) |
| 65 | { |
| 66 | int rc; |
| 67 | uint8_t tag; |
| 68 | uint8_t *value; |
| 69 | size_t value_len; |
| 70 | |
| 71 | /* specific parts */ |
| 72 | while (data_len > 0) { |
| 73 | enum gprs_gsup_iei iei; |
| 74 | |
| 75 | rc = gprs_shift_tlv(&data, &data_len, &tag, &value, &value_len); |
| 76 | if (rc < 0) |
Jacob Erlbeck | bce2061 | 2015-01-05 18:57:32 +0100 | [diff] [blame] | 77 | return -GMM_CAUSE_PROTO_ERR_UNSPEC; |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 78 | |
| 79 | iei = tag; |
| 80 | |
| 81 | switch (iei) { |
| 82 | case GPRS_GSUP_PDP_CONTEXT_ID_IE: |
| 83 | pdp_info->context_id = decode_big_endian(value, value_len); |
| 84 | break; |
| 85 | |
| 86 | case GPRS_GSUP_PDP_TYPE_IE: |
| 87 | pdp_info->pdp_type = |
| 88 | decode_big_endian(value, value_len) & 0x0fff; |
| 89 | break; |
| 90 | |
| 91 | case GPRS_GSUP_ACCESS_POINT_NAME_IE: |
| 92 | pdp_info->apn_enc = value; |
| 93 | pdp_info->apn_enc_len = value_len; |
| 94 | break; |
| 95 | |
| 96 | default: |
| 97 | LOGP(DGPRS, LOGL_ERROR, |
| 98 | "GSUP IE type %d not expected in PDP info\n", iei); |
| 99 | continue; |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | return 0; |
| 104 | } |
| 105 | |
| 106 | static int decode_auth_info(uint8_t *data, size_t data_len, |
| 107 | struct gsm_auth_tuple *auth_tuple) |
| 108 | { |
| 109 | int rc; |
| 110 | uint8_t tag; |
| 111 | uint8_t *value; |
| 112 | size_t value_len; |
| 113 | enum gprs_gsup_iei iei; |
| 114 | |
| 115 | /* specific parts */ |
| 116 | while (data_len > 0) { |
| 117 | rc = gprs_shift_tlv(&data, &data_len, &tag, &value, &value_len); |
| 118 | if (rc < 0) |
Jacob Erlbeck | bce2061 | 2015-01-05 18:57:32 +0100 | [diff] [blame] | 119 | return -GMM_CAUSE_PROTO_ERR_UNSPEC; |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 120 | |
| 121 | iei = tag; |
| 122 | |
| 123 | switch (iei) { |
| 124 | case GPRS_GSUP_RAND_IE: |
| 125 | if (value_len != sizeof(auth_tuple->rand)) |
| 126 | goto parse_error; |
| 127 | |
| 128 | memcpy(auth_tuple->rand, value, value_len); |
| 129 | break; |
| 130 | |
| 131 | case GPRS_GSUP_SRES_IE: |
| 132 | if (value_len != sizeof(auth_tuple->sres)) |
| 133 | goto parse_error; |
| 134 | |
| 135 | memcpy(auth_tuple->sres, value, value_len); |
| 136 | break; |
| 137 | |
| 138 | case GPRS_GSUP_KC_IE: |
| 139 | if (value_len != sizeof(auth_tuple->kc)) |
| 140 | goto parse_error; |
| 141 | |
| 142 | memcpy(auth_tuple->kc, value, value_len); |
| 143 | break; |
| 144 | |
| 145 | default: |
| 146 | LOGP(DGPRS, LOGL_ERROR, |
| 147 | "GSUP IE type %d not expected in PDP info\n", iei); |
| 148 | continue; |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | return 0; |
| 153 | |
| 154 | parse_error: |
| 155 | LOGP(DGPRS, LOGL_ERROR, |
| 156 | "GSUP IE type %d, length %d invalid in PDP info\n", iei, value_len); |
| 157 | |
| 158 | return -1; |
| 159 | } |
| 160 | |
| 161 | int gprs_gsup_decode(const uint8_t *const_data, size_t data_len, |
| 162 | struct gprs_gsup_message *gsup_msg) |
| 163 | { |
| 164 | int rc; |
| 165 | uint8_t tag; |
| 166 | /* the shift/match functions expect non-const pointers, but we'll |
| 167 | * either copy the data or cast pointers back to const before returning |
| 168 | * them |
| 169 | */ |
| 170 | uint8_t *data = (uint8_t *)const_data; |
| 171 | uint8_t *value; |
| 172 | size_t value_len; |
| 173 | static const struct gprs_gsup_pdp_info empty_pdp_info = {0}; |
| 174 | static const struct gsm_auth_tuple empty_auth_info = {0}; |
Jacob Erlbeck | 1610626 | 2015-01-12 13:54:39 +0100 | [diff] [blame] | 175 | static const struct gprs_gsup_message empty_gsup_message = {0}; |
| 176 | |
| 177 | *gsup_msg = empty_gsup_message; |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 178 | |
| 179 | /* generic part */ |
Jacob Erlbeck | 424ffa4 | 2015-01-12 13:23:05 +0100 | [diff] [blame] | 180 | rc = gprs_shift_v_fixed(&data, &data_len, 1, &value); |
| 181 | if (rc < 0) |
| 182 | return -GMM_CAUSE_INV_MAND_INFO; |
| 183 | |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 184 | gsup_msg->message_type = decode_big_endian(value, 1); |
| 185 | |
| 186 | rc = gprs_match_tlv(&data, &data_len, GPRS_GSUP_IMSI_IE, |
| 187 | &value, &value_len); |
| 188 | |
| 189 | if (rc <= 0) |
| 190 | return -GMM_CAUSE_INV_MAND_INFO; |
| 191 | |
| 192 | if (value_len * 2 + 1 > sizeof(gsup_msg->imsi)) |
| 193 | return -GMM_CAUSE_INV_MAND_INFO; |
| 194 | |
| 195 | /* Note that gsm48_decode_bcd_number expects the number of encoded IMSI |
| 196 | * octets in the first octet. By coincidence (the TLV encoding) the byte |
| 197 | * before the value part already contains this length so we can use it |
| 198 | * here. |
| 199 | */ |
| 200 | OSMO_ASSERT(value[-1] == value_len); |
| 201 | gsm48_decode_bcd_number(gsup_msg->imsi, sizeof(gsup_msg->imsi), |
| 202 | value - 1, 0); |
| 203 | |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 204 | /* specific parts */ |
| 205 | while (data_len > 0) { |
| 206 | enum gprs_gsup_iei iei; |
| 207 | struct gprs_gsup_pdp_info pdp_info; |
| 208 | struct gsm_auth_tuple auth_info; |
| 209 | |
| 210 | rc = gprs_shift_tlv(&data, &data_len, &tag, &value, &value_len); |
| 211 | if (rc < 0) |
| 212 | return -GMM_CAUSE_PROTO_ERR_UNSPEC; |
| 213 | |
| 214 | iei = tag; |
| 215 | |
| 216 | switch (iei) { |
| 217 | case GPRS_GSUP_IMSI_IE: |
| 218 | case GPRS_GSUP_PDP_TYPE_IE: |
| 219 | case GPRS_GSUP_ACCESS_POINT_NAME_IE: |
| 220 | case GPRS_GSUP_RAND_IE: |
| 221 | case GPRS_GSUP_SRES_IE: |
| 222 | case GPRS_GSUP_KC_IE: |
| 223 | LOGP(DGPRS, LOGL_NOTICE, |
| 224 | "GSUP IE type %d not expected (ignored)\n", iei); |
| 225 | continue; |
| 226 | |
| 227 | case GPRS_GSUP_CAUSE_IE: |
| 228 | gsup_msg->cause = decode_big_endian(value, value_len); |
| 229 | break; |
| 230 | |
| 231 | case GPRS_GSUP_CANCEL_TYPE_IE: |
| 232 | gsup_msg->cancel_type = |
| 233 | decode_big_endian(value, value_len) + 1; |
| 234 | break; |
| 235 | |
| 236 | case GPRS_GSUP_PDP_INFO_COMPL_IE: |
| 237 | gsup_msg->pdp_info_compl = 1; |
| 238 | break; |
| 239 | |
Jacob Erlbeck | 69d2713 | 2015-01-15 11:50:08 +0100 | [diff] [blame] | 240 | case GPRS_GSUP_FREEZE_PTMSI_IE: |
| 241 | gsup_msg->freeze_ptmsi = 1; |
| 242 | break; |
| 243 | |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 244 | case GPRS_GSUP_PDP_CONTEXT_ID_IE: |
| 245 | /* When these IE appear in the top-level part of the |
| 246 | * message, they are used by Delete Subscr Info to delete |
| 247 | * single entries. We don't have an extra list for |
| 248 | * these but use the PDP info list instead */ |
| 249 | |
| 250 | /* fall through */ |
| 251 | |
| 252 | case GPRS_GSUP_PDP_INFO_IE: |
| 253 | if (gsup_msg->num_pdp_infos >= GPRS_GSUP_MAX_NUM_PDP_INFO) { |
| 254 | LOGP(DGPRS, LOGL_ERROR, |
| 255 | "GSUP IE type %d (PDP_INFO) max exceeded\n", |
| 256 | iei); |
| 257 | return -GMM_CAUSE_COND_IE_ERR; |
| 258 | } |
| 259 | |
Jacob Erlbeck | 1610626 | 2015-01-12 13:54:39 +0100 | [diff] [blame] | 260 | pdp_info = empty_pdp_info; |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 261 | |
| 262 | if (iei == GPRS_GSUP_PDP_INFO_IE) { |
| 263 | rc = decode_pdp_info(value, value_len, &pdp_info); |
| 264 | if (rc < 0) |
| 265 | return rc; |
| 266 | pdp_info.have_info = 1; |
| 267 | } else { |
| 268 | pdp_info.context_id = |
| 269 | decode_big_endian(value, value_len); |
| 270 | } |
| 271 | |
| 272 | gsup_msg->pdp_infos[gsup_msg->num_pdp_infos++] = |
| 273 | pdp_info; |
| 274 | break; |
| 275 | |
| 276 | case GPRS_GSUP_AUTH_TUPLE_IE: |
| 277 | if (gsup_msg->num_auth_tuples >= GPRS_GSUP_MAX_NUM_AUTH_INFO) { |
| 278 | LOGP(DGPRS, LOGL_ERROR, |
| 279 | "GSUP IE type %d (AUTH_INFO) max exceeded\n", |
| 280 | iei); |
| 281 | return -GMM_CAUSE_INV_MAND_INFO; |
| 282 | } |
| 283 | |
Jacob Erlbeck | 1610626 | 2015-01-12 13:54:39 +0100 | [diff] [blame] | 284 | auth_info = empty_auth_info; |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 285 | auth_info.key_seq = gsup_msg->num_auth_tuples; |
| 286 | |
| 287 | rc = decode_auth_info(value, value_len, &auth_info); |
| 288 | if (rc < 0) |
| 289 | return rc; |
| 290 | |
| 291 | gsup_msg->auth_tuples[gsup_msg->num_auth_tuples++] = |
| 292 | auth_info; |
| 293 | break; |
| 294 | default: |
| 295 | LOGP(DGPRS, LOGL_NOTICE, |
| 296 | "GSUP IE type %d unknown\n", iei); |
| 297 | continue; |
| 298 | } |
| 299 | } |
| 300 | |
| 301 | return 0; |
| 302 | } |
| 303 | |
| 304 | static void encode_pdp_info(struct msgb *msg, enum gprs_gsup_iei iei, |
| 305 | const struct gprs_gsup_pdp_info *pdp_info) |
| 306 | { |
| 307 | uint8_t *len_field; |
| 308 | size_t old_len; |
| 309 | uint8_t u8; |
| 310 | |
| 311 | len_field = msgb_tlv_put(msg, iei, 0, NULL) - 1; |
| 312 | old_len = msgb_length(msg); |
| 313 | |
| 314 | u8 = pdp_info->context_id; |
| 315 | msgb_tlv_put(msg, GPRS_GSUP_PDP_CONTEXT_ID_IE, sizeof(u8), &u8); |
| 316 | |
| 317 | if (pdp_info->pdp_type) { |
| 318 | msgb_tlv_put(msg, GPRS_GSUP_PDP_TYPE_IE, |
| 319 | GPRS_GSUP_PDP_TYPE_SIZE, |
| 320 | encode_big_endian(pdp_info->pdp_type | 0xf000, |
| 321 | GPRS_GSUP_PDP_TYPE_SIZE)); |
| 322 | } |
| 323 | |
| 324 | if (pdp_info->apn_enc) { |
| 325 | msgb_tlv_put(msg, GPRS_GSUP_ACCESS_POINT_NAME_IE, |
| 326 | pdp_info->apn_enc_len, pdp_info->apn_enc); |
| 327 | } |
| 328 | |
| 329 | /* Update length field */ |
| 330 | *len_field = msgb_length(msg) - old_len; |
| 331 | } |
| 332 | |
| 333 | static void encode_auth_info(struct msgb *msg, enum gprs_gsup_iei iei, |
| 334 | const struct gsm_auth_tuple *auth_tuple) |
| 335 | { |
| 336 | uint8_t *len_field; |
| 337 | size_t old_len; |
| 338 | |
| 339 | len_field = msgb_tlv_put(msg, iei, 0, NULL) - 1; |
| 340 | old_len = msgb_length(msg); |
| 341 | |
| 342 | msgb_tlv_put(msg, GPRS_GSUP_RAND_IE, |
| 343 | sizeof(auth_tuple->rand), auth_tuple->rand); |
| 344 | |
| 345 | msgb_tlv_put(msg, GPRS_GSUP_SRES_IE, |
| 346 | sizeof(auth_tuple->sres), auth_tuple->sres); |
| 347 | |
| 348 | msgb_tlv_put(msg, GPRS_GSUP_KC_IE, |
| 349 | sizeof(auth_tuple->kc), auth_tuple->kc); |
| 350 | |
| 351 | /* Update length field */ |
| 352 | *len_field = msgb_length(msg) - old_len; |
| 353 | } |
| 354 | |
| 355 | void gprs_gsup_encode(struct msgb *msg, const struct gprs_gsup_message *gsup_msg) |
| 356 | { |
| 357 | uint8_t u8; |
| 358 | int idx; |
| 359 | uint8_t bcd_buf[GSM48_MI_SIZE] = {0}; |
| 360 | size_t bcd_len; |
| 361 | |
| 362 | /* generic part */ |
| 363 | OSMO_ASSERT(gsup_msg->message_type); |
| 364 | msgb_v_put(msg, gsup_msg->message_type); |
| 365 | |
| 366 | bcd_len = gsm48_encode_bcd_number(bcd_buf, sizeof(bcd_buf), 0, |
| 367 | gsup_msg->imsi); |
| 368 | |
| 369 | OSMO_ASSERT(bcd_len > 1); |
| 370 | |
| 371 | /* Note that gsm48_encode_bcd_number puts the length into the first |
| 372 | * octet. Since msgb_tlv_put will add this length byte, we'll have to |
| 373 | * skip it */ |
| 374 | msgb_tlv_put(msg, GPRS_GSUP_IMSI_IE, bcd_len - 1, &bcd_buf[1]); |
| 375 | |
| 376 | /* specific parts */ |
| 377 | if ((u8 = gsup_msg->cause)) |
| 378 | msgb_tlv_put(msg, GPRS_GSUP_CAUSE_IE, sizeof(u8), &u8); |
| 379 | |
| 380 | if ((u8 = gsup_msg->cancel_type)) { |
| 381 | u8 -= 1; |
| 382 | msgb_tlv_put(msg, GPRS_GSUP_CANCEL_TYPE_IE, sizeof(u8), &u8); |
| 383 | } |
| 384 | |
| 385 | if (gsup_msg->pdp_info_compl) |
| 386 | msgb_tlv_put(msg, GPRS_GSUP_PDP_INFO_COMPL_IE, 0, &u8); |
| 387 | |
Jacob Erlbeck | 69d2713 | 2015-01-15 11:50:08 +0100 | [diff] [blame] | 388 | if (gsup_msg->freeze_ptmsi) |
| 389 | msgb_tlv_put(msg, GPRS_GSUP_FREEZE_PTMSI_IE, 0, &u8); |
| 390 | |
Jacob Erlbeck | f3a271f | 2014-12-11 16:54:14 +0100 | [diff] [blame] | 391 | for (idx = 0; idx < gsup_msg->num_pdp_infos; idx++) { |
| 392 | const struct gprs_gsup_pdp_info *pdp_info; |
| 393 | |
| 394 | pdp_info = &gsup_msg->pdp_infos[idx]; |
| 395 | |
| 396 | if (pdp_info->context_id == 0) |
| 397 | continue; |
| 398 | |
| 399 | if (pdp_info->have_info) { |
| 400 | encode_pdp_info(msg, GPRS_GSUP_PDP_INFO_IE, pdp_info); |
| 401 | } else { |
| 402 | u8 = pdp_info->context_id; |
| 403 | msgb_tlv_put(msg, GPRS_GSUP_PDP_CONTEXT_ID_IE, |
| 404 | sizeof(u8), &u8); |
| 405 | } |
| 406 | } |
| 407 | |
| 408 | for (idx = 0; idx < gsup_msg->num_auth_tuples; idx++) { |
| 409 | const struct gsm_auth_tuple *auth_info; |
| 410 | |
| 411 | auth_info = &gsup_msg->auth_tuples[idx]; |
| 412 | |
| 413 | if (auth_info->key_seq == GSM_KEY_SEQ_INVAL) |
| 414 | continue; |
| 415 | |
| 416 | encode_auth_info(msg, GPRS_GSUP_AUTH_TUPLE_IE, auth_info); |
| 417 | } |
| 418 | } |