From f3a271fa73ea58a628a51aa310e1da20a5526f31 Mon Sep 17 00:00:00 2001 From: Jacob Erlbeck Date: Thu, 11 Dec 2014 16:54:14 +0100 Subject: gprs: Add encoder/decoder for the Subscriber Update Protocol This patch adds functions to encode and decode GSUP messages. This does not include the layer 1 framing (IPA). The messages so far supported are: send_auth_info_*, update_location_*, location_cancellation_*. Sponsored-by: On-Waves ehf --- openbsc/src/gprs/gprs_gsup_messages.c | 405 ++++++++++++++++++++++++++++++++++ 1 file changed, 405 insertions(+) create mode 100644 openbsc/src/gprs/gprs_gsup_messages.c (limited to 'openbsc/src/gprs/gprs_gsup_messages.c') diff --git a/openbsc/src/gprs/gprs_gsup_messages.c b/openbsc/src/gprs/gprs_gsup_messages.c new file mode 100644 index 000000000..c3d187db6 --- /dev/null +++ b/openbsc/src/gprs/gprs_gsup_messages.c @@ -0,0 +1,405 @@ +/* GPRS Subscriber Update Protocol message encoder/decoder */ + +/* + * (C) 2014 by Sysmocom s.f.m.c. GmbH + * All Rights Reserved + * + * Author: Jacob Erlbeck + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License as published by + * the Free Software Foundation; either version 3 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 Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see . + * + */ + +#include + +#include +#include + +#include +#include + +#include + + +static uint64_t decode_big_endian(const uint8_t *data, size_t data_len) +{ + uint64_t value = 0; + + while (data_len > 0) { + value = (value << 8) + *data; + data += 1; + data_len -= 1; + } + + return value; +} + +static uint8_t *encode_big_endian(uint64_t value, size_t data_len) +{ + static uint8_t buf[sizeof(uint64_t)]; + int idx; + + OSMO_ASSERT(data_len <= ARRAY_SIZE(buf)); + + for (idx = data_len - 1; idx >= 0; idx--) { + buf[idx] = (uint8_t)value; + value = value >> 8; + } + + return buf; +} + +static int decode_pdp_info(uint8_t *data, size_t data_len, + struct gprs_gsup_pdp_info *pdp_info) +{ + int rc; + uint8_t tag; + uint8_t *value; + size_t value_len; + + /* specific parts */ + while (data_len > 0) { + enum gprs_gsup_iei iei; + + rc = gprs_shift_tlv(&data, &data_len, &tag, &value, &value_len); + if (rc < 0) + return rc; + + iei = tag; + + switch (iei) { + case GPRS_GSUP_PDP_CONTEXT_ID_IE: + pdp_info->context_id = decode_big_endian(value, value_len); + break; + + case GPRS_GSUP_PDP_TYPE_IE: + pdp_info->pdp_type = + decode_big_endian(value, value_len) & 0x0fff; + break; + + case GPRS_GSUP_ACCESS_POINT_NAME_IE: + pdp_info->apn_enc = value; + pdp_info->apn_enc_len = value_len; + break; + + default: + LOGP(DGPRS, LOGL_ERROR, + "GSUP IE type %d not expected in PDP info\n", iei); + continue; + } + } + + return 0; +} + +static int decode_auth_info(uint8_t *data, size_t data_len, + struct gsm_auth_tuple *auth_tuple) +{ + int rc; + uint8_t tag; + uint8_t *value; + size_t value_len; + enum gprs_gsup_iei iei; + + /* specific parts */ + while (data_len > 0) { + rc = gprs_shift_tlv(&data, &data_len, &tag, &value, &value_len); + if (rc < 0) + return rc; + + iei = tag; + + switch (iei) { + case GPRS_GSUP_RAND_IE: + if (value_len != sizeof(auth_tuple->rand)) + goto parse_error; + + memcpy(auth_tuple->rand, value, value_len); + break; + + case GPRS_GSUP_SRES_IE: + if (value_len != sizeof(auth_tuple->sres)) + goto parse_error; + + memcpy(auth_tuple->sres, value, value_len); + break; + + case GPRS_GSUP_KC_IE: + if (value_len != sizeof(auth_tuple->kc)) + goto parse_error; + + memcpy(auth_tuple->kc, value, value_len); + break; + + default: + LOGP(DGPRS, LOGL_ERROR, + "GSUP IE type %d not expected in PDP info\n", iei); + continue; + } + } + + return 0; + +parse_error: + LOGP(DGPRS, LOGL_ERROR, + "GSUP IE type %d, length %d invalid in PDP info\n", iei, value_len); + + return -1; +} + +int gprs_gsup_decode(const uint8_t *const_data, size_t data_len, + struct gprs_gsup_message *gsup_msg) +{ + int rc; + uint8_t tag; + /* the shift/match functions expect non-const pointers, but we'll + * either copy the data or cast pointers back to const before returning + * them + */ + uint8_t *data = (uint8_t *)const_data; + uint8_t *value; + size_t value_len; + static const struct gprs_gsup_pdp_info empty_pdp_info = {0}; + static const struct gsm_auth_tuple empty_auth_info = {0}; + + /* generic part */ + gprs_shift_v_fixed(&data, &data_len, 1, &value); + gsup_msg->message_type = decode_big_endian(value, 1); + + rc = gprs_match_tlv(&data, &data_len, GPRS_GSUP_IMSI_IE, + &value, &value_len); + + if (rc <= 0) + return -GMM_CAUSE_INV_MAND_INFO; + + if (value_len * 2 + 1 > sizeof(gsup_msg->imsi)) + return -GMM_CAUSE_INV_MAND_INFO; + + /* Note that gsm48_decode_bcd_number expects the number of encoded IMSI + * octets in the first octet. By coincidence (the TLV encoding) the byte + * before the value part already contains this length so we can use it + * here. + */ + OSMO_ASSERT(value[-1] == value_len); + gsm48_decode_bcd_number(gsup_msg->imsi, sizeof(gsup_msg->imsi), + value - 1, 0); + + /* specific parts */ + while (data_len > 0) { + enum gprs_gsup_iei iei; + struct gprs_gsup_pdp_info pdp_info; + struct gsm_auth_tuple auth_info; + + rc = gprs_shift_tlv(&data, &data_len, &tag, &value, &value_len); + if (rc < 0) + return -GMM_CAUSE_PROTO_ERR_UNSPEC; + + iei = tag; + + switch (iei) { + case GPRS_GSUP_IMSI_IE: + case GPRS_GSUP_PDP_TYPE_IE: + case GPRS_GSUP_ACCESS_POINT_NAME_IE: + case GPRS_GSUP_RAND_IE: + case GPRS_GSUP_SRES_IE: + case GPRS_GSUP_KC_IE: + LOGP(DGPRS, LOGL_NOTICE, + "GSUP IE type %d not expected (ignored)\n", iei); + continue; + + case GPRS_GSUP_CAUSE_IE: + gsup_msg->cause = decode_big_endian(value, value_len); + break; + + case GPRS_GSUP_CANCEL_TYPE_IE: + gsup_msg->cancel_type = + decode_big_endian(value, value_len) + 1; + break; + + case GPRS_GSUP_PDP_INFO_COMPL_IE: + gsup_msg->pdp_info_compl = 1; + break; + + case GPRS_GSUP_PDP_CONTEXT_ID_IE: + /* When these IE appear in the top-level part of the + * message, they are used by Delete Subscr Info to delete + * single entries. We don't have an extra list for + * these but use the PDP info list instead */ + + /* fall through */ + + case GPRS_GSUP_PDP_INFO_IE: + if (gsup_msg->num_pdp_infos >= GPRS_GSUP_MAX_NUM_PDP_INFO) { + LOGP(DGPRS, LOGL_ERROR, + "GSUP IE type %d (PDP_INFO) max exceeded\n", + iei); + return -GMM_CAUSE_COND_IE_ERR; + } + + memcpy(&pdp_info, &empty_pdp_info, sizeof(pdp_info)); + + if (iei == GPRS_GSUP_PDP_INFO_IE) { + rc = decode_pdp_info(value, value_len, &pdp_info); + if (rc < 0) + return rc; + pdp_info.have_info = 1; + } else { + pdp_info.context_id = + decode_big_endian(value, value_len); + } + + gsup_msg->pdp_infos[gsup_msg->num_pdp_infos++] = + pdp_info; + break; + + case GPRS_GSUP_AUTH_TUPLE_IE: + if (gsup_msg->num_auth_tuples >= GPRS_GSUP_MAX_NUM_AUTH_INFO) { + LOGP(DGPRS, LOGL_ERROR, + "GSUP IE type %d (AUTH_INFO) max exceeded\n", + iei); + return -GMM_CAUSE_INV_MAND_INFO; + } + + memcpy(&auth_info, &empty_auth_info, sizeof(auth_info)); + auth_info.key_seq = gsup_msg->num_auth_tuples; + + rc = decode_auth_info(value, value_len, &auth_info); + if (rc < 0) + return rc; + + gsup_msg->auth_tuples[gsup_msg->num_auth_tuples++] = + auth_info; + break; + default: + LOGP(DGPRS, LOGL_NOTICE, + "GSUP IE type %d unknown\n", iei); + continue; + } + } + + return 0; +} + +static void encode_pdp_info(struct msgb *msg, enum gprs_gsup_iei iei, + const struct gprs_gsup_pdp_info *pdp_info) +{ + uint8_t *len_field; + size_t old_len; + uint8_t u8; + + len_field = msgb_tlv_put(msg, iei, 0, NULL) - 1; + old_len = msgb_length(msg); + + u8 = pdp_info->context_id; + msgb_tlv_put(msg, GPRS_GSUP_PDP_CONTEXT_ID_IE, sizeof(u8), &u8); + + if (pdp_info->pdp_type) { + msgb_tlv_put(msg, GPRS_GSUP_PDP_TYPE_IE, + GPRS_GSUP_PDP_TYPE_SIZE, + encode_big_endian(pdp_info->pdp_type | 0xf000, + GPRS_GSUP_PDP_TYPE_SIZE)); + } + + if (pdp_info->apn_enc) { + msgb_tlv_put(msg, GPRS_GSUP_ACCESS_POINT_NAME_IE, + pdp_info->apn_enc_len, pdp_info->apn_enc); + } + + /* Update length field */ + *len_field = msgb_length(msg) - old_len; +} + +static void encode_auth_info(struct msgb *msg, enum gprs_gsup_iei iei, + const struct gsm_auth_tuple *auth_tuple) +{ + uint8_t *len_field; + size_t old_len; + + len_field = msgb_tlv_put(msg, iei, 0, NULL) - 1; + old_len = msgb_length(msg); + + msgb_tlv_put(msg, GPRS_GSUP_RAND_IE, + sizeof(auth_tuple->rand), auth_tuple->rand); + + msgb_tlv_put(msg, GPRS_GSUP_SRES_IE, + sizeof(auth_tuple->sres), auth_tuple->sres); + + msgb_tlv_put(msg, GPRS_GSUP_KC_IE, + sizeof(auth_tuple->kc), auth_tuple->kc); + + /* Update length field */ + *len_field = msgb_length(msg) - old_len; +} + +void gprs_gsup_encode(struct msgb *msg, const struct gprs_gsup_message *gsup_msg) +{ + uint8_t u8; + int idx; + uint8_t bcd_buf[GSM48_MI_SIZE] = {0}; + size_t bcd_len; + + /* generic part */ + OSMO_ASSERT(gsup_msg->message_type); + msgb_v_put(msg, gsup_msg->message_type); + + bcd_len = gsm48_encode_bcd_number(bcd_buf, sizeof(bcd_buf), 0, + gsup_msg->imsi); + + OSMO_ASSERT(bcd_len > 1); + + /* Note that gsm48_encode_bcd_number puts the length into the first + * octet. Since msgb_tlv_put will add this length byte, we'll have to + * skip it */ + msgb_tlv_put(msg, GPRS_GSUP_IMSI_IE, bcd_len - 1, &bcd_buf[1]); + + /* specific parts */ + if ((u8 = gsup_msg->cause)) + msgb_tlv_put(msg, GPRS_GSUP_CAUSE_IE, sizeof(u8), &u8); + + if ((u8 = gsup_msg->cancel_type)) { + u8 -= 1; + msgb_tlv_put(msg, GPRS_GSUP_CANCEL_TYPE_IE, sizeof(u8), &u8); + } + + if (gsup_msg->pdp_info_compl) + msgb_tlv_put(msg, GPRS_GSUP_PDP_INFO_COMPL_IE, 0, &u8); + + for (idx = 0; idx < gsup_msg->num_pdp_infos; idx++) { + const struct gprs_gsup_pdp_info *pdp_info; + + pdp_info = &gsup_msg->pdp_infos[idx]; + + if (pdp_info->context_id == 0) + continue; + + if (pdp_info->have_info) { + encode_pdp_info(msg, GPRS_GSUP_PDP_INFO_IE, pdp_info); + } else { + u8 = pdp_info->context_id; + msgb_tlv_put(msg, GPRS_GSUP_PDP_CONTEXT_ID_IE, + sizeof(u8), &u8); + } + } + + for (idx = 0; idx < gsup_msg->num_auth_tuples; idx++) { + const struct gsm_auth_tuple *auth_info; + + auth_info = &gsup_msg->auth_tuples[idx]; + + if (auth_info->key_seq == GSM_KEY_SEQ_INVAL) + continue; + + encode_auth_info(msg, GPRS_GSUP_AUTH_TUPLE_IE, auth_info); + } +} -- cgit v1.2.3