/* Osmocom Authentication Protocol message encoder/decoder */ /* (C) 2015-2016 by sysmocom s.f.m.c. GmbH * All Rights Reserved * * Author: Neels Hofmeyr * * 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. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . * */ #include #include #include #include #include #include /*! \brief Decode OAP message data. * \param[out] oap_msg Parsed data is written to this instance. * \param[in] data Pointer to the data buffer containing the OAP message. * \param[in] data_len Length of the OAP message data. * \returns 0 on success, a negative cause value on failure. */ int osmo_oap_decode(struct osmo_oap_message *oap_msg, const uint8_t *const_data, size_t data_len) { 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; memset(oap_msg, 0, sizeof(*oap_msg)); /* message type */ rc = osmo_shift_v_fixed(&data, &data_len, 1, &value); if (rc < 0) return -GMM_CAUSE_INV_MAND_INFO; oap_msg->message_type = osmo_decode_big_endian(value, 1); /* specific parts */ while (data_len > 0) { enum osmo_oap_iei iei; rc = osmo_shift_tlv(&data, &data_len, &tag, &value, &value_len); if (rc < 0) return -GMM_CAUSE_PROTO_ERR_UNSPEC; iei = tag; switch (iei) { case OAP_CLIENT_ID_IE: if (value_len != 2) { LOGP(DLOAP, LOGL_NOTICE, "OAP IE type client ID (%d) should be 2 octets, but has %d\n", (int)iei, (int)value_len); return -GMM_CAUSE_PROTO_ERR_UNSPEC; } oap_msg->client_id = osmo_decode_big_endian(value, value_len); if (oap_msg->client_id == 0) { LOGP(DLOAP, LOGL_NOTICE, "OAP IE type client ID (%d): client ID must be nonzero.\n", (int)iei); return -GMM_CAUSE_PROTO_ERR_UNSPEC; } break; case OAP_AUTN_IE: if (value_len != sizeof(oap_msg->autn)) { LOGP(DLOAP, LOGL_NOTICE, "OAP IE type AUTN (%d) should be %d octets, but has %d\n", (int)iei, (int)sizeof(oap_msg->autn), (int)value_len); return -GMM_CAUSE_PROTO_ERR_UNSPEC; } memcpy(oap_msg->autn, value, value_len); oap_msg->autn_present = value_len; break; case OAP_RAND_IE: if (value_len != sizeof(oap_msg->rand)) { LOGP(DLOAP, LOGL_NOTICE, "OAP IE type RAND (%d) should be %d octets, but has %d\n", (int)iei, (int)sizeof(oap_msg->rand), (int)value_len); return -GMM_CAUSE_PROTO_ERR_UNSPEC; } memcpy(oap_msg->rand, value, value_len); oap_msg->rand_present = value_len; break; case OAP_XRES_IE: if (value_len != sizeof(oap_msg->xres)) { LOGP(DLOAP, LOGL_NOTICE, "OAP IE type XRES (%d) should be %d octets, but has %d\n", (int)iei, (int)sizeof(oap_msg->xres), (int)value_len); return -GMM_CAUSE_PROTO_ERR_UNSPEC; } memcpy(oap_msg->xres, value, value_len); oap_msg->xres_present = value_len; break; case OAP_AUTS_IE: if (value_len != sizeof(oap_msg->auts)) { LOGP(DLOAP, LOGL_NOTICE, "OAP IE type AUTS (%d) should be %d octets, but has %d\n", (int)iei, (int)sizeof(oap_msg->auts), (int)value_len); return -GMM_CAUSE_PROTO_ERR_UNSPEC; } memcpy(oap_msg->auts, value, value_len); oap_msg->auts_present = value_len; break; case OAP_CAUSE_IE: if (value_len > 1) { LOGP(DLOAP, LOGL_ERROR, "OAP cause may not exceed one octet, is %d", (int)value_len); return -GMM_CAUSE_PROTO_ERR_UNSPEC; } oap_msg->cause = *value; break; default: LOGP(DLOAP, LOGL_NOTICE, "OAP IE type %d unknown\n", iei); continue; } } return 0; } /*! \brief Compose OAP message data. * \param[out] msg OAP message data is appended to this message buffer. * \param[in] oap_msg Elements to encode in the message data. */ void osmo_oap_encode(struct msgb *msg, const struct osmo_oap_message *oap_msg) { uint8_t u8; /* generic part */ OSMO_ASSERT(oap_msg->message_type); msgb_v_put(msg, (uint8_t)oap_msg->message_type); /* specific parts */ if ((u8 = oap_msg->cause)) msgb_tlv_put(msg, OAP_CAUSE_IE, sizeof(u8), &u8); if (oap_msg->client_id > 0) msgb_tlv_put(msg, OAP_CLIENT_ID_IE, sizeof(oap_msg->client_id), osmo_encode_big_endian(oap_msg->client_id, sizeof(oap_msg->client_id))); if (oap_msg->rand_present) msgb_tlv_put(msg, OAP_RAND_IE, sizeof(oap_msg->rand), oap_msg->rand); if (oap_msg->autn_present) msgb_tlv_put(msg, OAP_AUTN_IE, sizeof(oap_msg->autn), oap_msg->autn); if (oap_msg->auts_present) msgb_tlv_put(msg, OAP_AUTS_IE, sizeof(oap_msg->auts), oap_msg->auts); if (oap_msg->xres_present) msgb_tlv_put(msg, OAP_XRES_IE, sizeof(oap_msg->xres), oap_msg->xres); msg->l2h = msg->data; }