Add oap.[hc] and oap_messages.[hc].

Sponsored-by: On-Waves ehf
---
 openbsc/include/openbsc/Makefile.am    |   3 +-
 openbsc/include/openbsc/oap.h          |  77 ++++++++++
 openbsc/include/openbsc/oap_messages.h |  70 +++++++++
 openbsc/src/gprs/Makefile.am           |   3 +-
 openbsc/src/gprs/oap.c                 | 254 +++++++++++++++++++++++++++++++++
 openbsc/src/gprs/oap_messages.c        | 178 +++++++++++++++++++++++
 6 files changed, 583 insertions(+), 2 deletions(-)
 create mode 100644 openbsc/include/openbsc/oap.h
 create mode 100644 openbsc/include/openbsc/oap_messages.h
 create mode 100644 openbsc/src/gprs/oap.c
 create mode 100644 openbsc/src/gprs/oap_messages.c

diff --git a/openbsc/include/openbsc/Makefile.am 
b/openbsc/include/openbsc/Makefile.am
index 828f5bd..8a074c2 100644
--- a/openbsc/include/openbsc/Makefile.am
+++ b/openbsc/include/openbsc/Makefile.am
@@ -16,7 +16,8 @@ noinst_HEADERS = abis_nm.h abis_rsl.h db.h gsm_04_08.h 
gsm_data.h \
                arfcn_range_encode.h nat_rewrite_trie.h bsc_nat_callstats.h \
                osmux.h mgcp_transcode.h gprs_utils.h utils.h \
                 gprs_gb_parse.h smpp.h meas_feed.h gprs_gsup_messages.h \
-                gprs_gsup_client.h bsc_msg_filter.h
+                gprs_gsup_client.h bsc_msg_filter.h \
+                oap.h oap_messages.h

 openbsc_HEADERS = gsm_04_08.h meas_rep.h bsc_api.h
 openbscdir = $(includedir)/openbsc
diff --git a/openbsc/include/openbsc/oap.h b/openbsc/include/openbsc/oap.h
new file mode 100644
index 0000000..d106118
--- /dev/null
+++ b/openbsc/include/openbsc/oap.h
@@ -0,0 +1,77 @@
+/* Osmocom Authentication Protocol API */
+
+/* (C) 2015 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 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 <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+struct msgb;
+struct oap_message;
+
+/* This is the config part for vty. It is essentially copied in oap_state,
+ * where values are copied over once the config is considered valid. */
+struct oap_config {
+       uint16_t client_id;
+       int secret_k_present;
+       uint8_t secret_k[16];
+       int secret_opc_present;
+       uint8_t secret_opc[16];
+};
+
+/* The runtime state of the OAP client. client_id and the secrets are in fact
+ * duplicated from oap_config, so that a separate validation of the config data
+ * is possible, and so that only a struct oap_state* is passed around. */
+struct oap_state {
+       enum {
+               OAP_UNINITIALIZED = 0,  // just allocated.
+               OAP_DISABLED,           // disabled by config.
+               OAP_INITIALIZED,        // shared_secret valid.
+               OAP_REQUESTED_CHALLENGE,
+               OAP_SENT_CHALLENGE_RESULT,
+               OAP_REGISTERED
+       } state;
+       uint16_t client_id;
+       uint8_t secret_k[16];
+       uint8_t secret_opc[16];
+       int registration_failures;
+};
+
+/* From config, initialize state. Return 0 on success. */
+int oap_init(struct oap_config *config, struct oap_state *state);
+
+/* Construct an OAP registration message and return in *msg_tx. Use
+ * state->client_id and update state->state.
+ * Return 0 on success, or a negative value on error.
+ * If an error is returned, *msg_tx is guaranteed to be NULL. */
+int oap_register(struct oap_state *state, struct msgb **msg_tx);
+
+/* Decode and act on a received OAP message msg_rx. Update state->state.  If a
+ * non-NULL pointer is returned in *msg_tx, that msgb should be sent to the OAP
+ * server (and freed) by the caller. The received msg_rx is not freed.
+ * Return 0 on success, or a negative value on error.
+ * If an error is returned, *msg_tx is guaranteed to be NULL. */
+int oap_handle(struct oap_state *state, const struct msgb *msg_rx, struct msgb 
**msg_tx);
+
+/* Allocate a msgb and in it, return the encoded oap_msg. Return NULL on
+ * error. (Like oap_encode(), but also allocates a msgb.) */
+struct msgb *oap_encoded(const struct oap_message *oap_msg);
+
diff --git a/openbsc/include/openbsc/oap_messages.h 
b/openbsc/include/openbsc/oap_messages.h
new file mode 100644
index 0000000..a7a254c
--- /dev/null
+++ b/openbsc/include/openbsc/oap_messages.h
@@ -0,0 +1,70 @@
+/* Osmocom Authentication Protocol message encoder/decoder */
+
+/* (C) 2015 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 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 <http://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
+
+#include <stdint.h>
+#include <openbsc/gsm_04_08_gprs.h>
+#include <openbsc/gsm_data.h>
+
+/* Some numbers are out of sequence because (so far) they match gprs_gsup_iei.
+ */
+enum oap_iei {
+       OAP_CAUSE_IE                    = 0x02,
+       OAP_RAND_IE                     = 0x20,
+       OAP_AUTN_IE                     = 0x23,
+       OAP_XRES_IE                     = 0x24,
+       OAP_AUTS_IE                     = 0x25,
+       OAP_CLIENT_ID_IE                = 0x30,
+};
+
+enum oap_message_type {
+       OAP_MSGT_REGISTER_REQUEST       = 0b00000100,
+       OAP_MSGT_REGISTER_ERROR         = 0b00000101,
+       OAP_MSGT_REGISTER_RESULT        = 0b00000110,
+
+       OAP_MSGT_CHALLENGE_REQUEST      = 0b00001000,
+       OAP_MSGT_CHALLENGE_ERROR        = 0b00001001,
+       OAP_MSGT_CHALLENGE_RESULT       = 0b00001010,
+
+       OAP_MSGT_SYNC_REQUEST           = 0b00001100,
+       OAP_MSGT_SYNC_ERROR             = 0b00001101,
+       OAP_MSGT_SYNC_RESULT            = 0b00001110,
+};
+
+struct oap_message {
+       enum oap_message_type   message_type;
+       enum gsm48_gmm_cause    cause;
+       uint16_t                client_id;
+       int                     rand_present;
+       uint8_t                 rand[16];
+       int                     autn_present;
+       uint8_t                 autn[16];
+       int                     xres_present;
+       uint8_t                 xres[8];
+       int                     auts_present;
+       uint8_t                 auts[16];
+};
+
+int oap_decode(const uint8_t *data, size_t data_len,
+              struct oap_message *oap_msg);
+void oap_encode(struct msgb *msg, const struct oap_message *oap_msg);
+
diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index f46a402..0952d41 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -27,7 +27,8 @@ osmo_sgsn_SOURCES =   gprs_gmm.c gprs_sgsn.c gprs_sndcp.c 
gprs_sndcp_vty.c \
                        gprs_llc.c gprs_llc_parse.c gprs_llc_vty.c crc24.c \
                        sgsn_ctrl.c sgsn_auth.c gprs_subscriber.c \
                        gprs_gsup_messages.c gprs_utils.c gprs_gsup_client.c \
-                       gsm_04_08_gprs.c sgsn_cdr.c sgsn_ares.c
+                       gsm_04_08_gprs.c sgsn_cdr.c sgsn_ares.c \
+                       oap.c oap_messages.c
 osmo_sgsn_LDADD =      \
                        $(top_builddir)/src/libcommon/libcommon.a \
                        -lgtp $(OSMO_LIBS) $(LIBOSMOABIS_LIBS) $(LIBCARES_LIBS) 
-lrt
diff --git a/openbsc/src/gprs/oap.c b/openbsc/src/gprs/oap.c
new file mode 100644
index 0000000..2c17d04
--- /dev/null
+++ b/openbsc/src/gprs/oap.c
@@ -0,0 +1,254 @@
+/* Osmocom Authentication Protocol API */
+
+/* (C) 2015 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 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 <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/crypt/auth.h>
+
+#include <openbsc/oap.h>
+#include <openbsc/utils.h>
+#include <openbsc/debug.h>
+#include <openbsc/oap_messages.h>
+
+int oap_init(struct oap_config *config, struct oap_state *state)
+{
+       OSMO_ASSERT(state->state == OAP_UNINITIALIZED);
+
+       if (config->client_id == 0)
+               goto disable;
+
+       if (config->secret_k_present == 0) {
+               LOGP(DGPRS, LOGL_NOTICE, "OAP: client ID set, but secret K 
missing.\n");
+               goto disable;
+       }
+
+       if (config->secret_opc_present == 0) {
+               LOGP(DGPRS, LOGL_NOTICE, "OAP: client ID set, but secret OPC 
missing.\n");
+               goto disable;
+       }
+
+       state->client_id = config->client_id;
+       memcpy(state->secret_k, config->secret_k, sizeof(state->secret_k));
+       memcpy(state->secret_opc, config->secret_opc, 
sizeof(state->secret_opc));
+       state->state = OAP_INITIALIZED;
+       return 0;
+
+disable:
+       state->state = OAP_DISABLED;
+       return 0;
+}
+
+/* From the given state and received RAND and AUTN octets, validate the
+ * server's authenticity and formulate the matching milenage reply octets in
+ * *tx_xres. The state is not modified.
+ * On success, and if tx_res is not NULL, exactly 8 octets will be written to
+ * *tx_res. If not NULL, tx_res must point at allocated memory of at least 8
+ * octets. The caller will want to send XRES back to the server in a challenge
+ * response message and update the state.
+ * Return 0 on success; -1 if OAP is disabled; -2 if rx_random and rx_autn fail
+ * the authentication check; -3 for any other errors. */
+static int oap_evaluate_challenge(const struct oap_state *state,
+                                 const uint8_t *rx_random,
+                                 const uint8_t *rx_autn,
+                                 uint8_t *tx_xres)
+{
+       switch(state->state) {
+       case OAP_UNINITIALIZED:
+       case OAP_DISABLED:
+               return -1;
+       default:
+               break;
+       }
+
+       struct osmo_auth_vector vec;
+
+       struct osmo_sub_auth_data auth = {
+               .type           = OSMO_AUTH_TYPE_UMTS,
+               .algo           = OSMO_AUTH_ALG_MILENAGE,
+       };
+
+       OSMO_ASSERT(sizeof(auth.u.umts.k) == sizeof(state->secret_k));
+       OSMO_ASSERT(sizeof(auth.u.umts.opc) == sizeof(state->secret_opc));
+
+       memcpy(auth.u.umts.k, state->secret_k, sizeof(auth.u.umts.k));
+       memcpy(auth.u.umts.opc, state->secret_opc, sizeof(auth.u.umts.opc));
+       memset(auth.u.umts.amf, 0, 2);
+       auth.u.umts.sqn = 42; /* TODO */
+
+       memset(&vec, 0, sizeof(vec));
+       osmo_auth_gen_vec(&vec, &auth, rx_random);
+
+       if (vec.res_len != 8) {
+               LOGP(DGPRS, LOGL_ERROR, "OAP: Expected XRES to be 8 octets, got 
%d\n",
+                    vec.res_len);
+               return -3;
+       }
+
+       if (constant_time_cmp(vec.autn, rx_autn, sizeof(vec.autn)) != 0) {
+               LOGP(DGPRS, LOGL_ERROR, "OAP: AUTN mismatch!\n");
+               LOGP(DGPRS, LOGL_INFO, "OAP: AUTN from server: %s\n",
+                    osmo_hexdump_nospc(rx_autn, sizeof(vec.autn)));
+               LOGP(DGPRS, LOGL_INFO, "OAP: AUTN expected:    %s\n",
+                    osmo_hexdump_nospc(vec.autn, sizeof(vec.autn)));
+               return -2;
+       }
+
+       if (tx_xres != NULL)
+               memcpy(tx_xres, vec.res, 8);
+       return 0;
+}
+
+struct msgb *oap_encoded(const struct oap_message *oap_msg)
+{
+       struct msgb *msg = msgb_alloc_headroom(1000, 64, __func__);
+       OSMO_ASSERT(msg);
+       oap_encode(msg, oap_msg);
+       return msg;
+}
+
+/* Create a new msgb containing an OAP registration message.
+ * On error, return NULL. */
+static struct msgb* oap_msg_register(uint16_t client_id)
+{
+       if (client_id < 1) {
+               LOGP(DGPRS, LOGL_ERROR, "OAP: Invalid client ID: %d\n", 
client_id);
+               return NULL;
+       }
+
+       struct oap_message oap_msg = {0};
+       oap_msg.message_type = OAP_MSGT_REGISTER_REQUEST;
+       oap_msg.client_id = client_id;
+       return oap_encoded(&oap_msg);
+}
+
+int oap_register(struct oap_state *state, struct msgb **msg_tx)
+{
+       *msg_tx = oap_msg_register(state->client_id);
+       if (!(*msg_tx))
+               return -1;
+
+       state->state = OAP_REQUESTED_CHALLENGE;
+       return 0;
+}
+
+/* Create a new msgb containing an OAP challenge response message.
+ * xres must point at 8 octets to return as challenge response.
+ * On error, return NULL. */
+static struct msgb* oap_msg_challenge_response(uint8_t *xres)
+{
+       struct oap_message oap_reply = {0};
+
+       oap_reply.message_type = OAP_MSGT_CHALLENGE_RESULT;
+       memcpy(oap_reply.xres, xres, sizeof(oap_reply.xres));
+       oap_reply.xres_present = 1;
+       return oap_encoded(&oap_reply);
+}
+
+static int handle_challenge(struct oap_state *state,
+                           struct oap_message *oap_rx,
+                           struct msgb **msg_tx)
+{
+       int rc;
+       if (!(oap_rx->rand_present && oap_rx->autn_present)) {
+               LOGP(DGPRS, LOGL_ERROR,
+                    "OAP challenge incomplete (rand_present: %d, autn_present: 
%d)\n",
+                    oap_rx->rand_present, oap_rx->autn_present);
+               rc = -2;
+               goto failure;
+       }
+
+       uint8_t xres[8];
+       rc = oap_evaluate_challenge(state,
+                                   oap_rx->rand,
+                                   oap_rx->autn,
+                                   xres);
+       if (rc < 0)
+               goto failure;
+
+       *msg_tx = oap_msg_challenge_response(xres);
+       if ((*msg_tx) == NULL) {
+               rc = -1;
+               goto failure;
+       }
+
+       state->state = OAP_SENT_CHALLENGE_RESULT;
+       return 0;
+
+failure:
+       OSMO_ASSERT(rc < 0);
+       state->state = OAP_INITIALIZED;
+       return rc;
+}
+
+int oap_handle(struct oap_state *state, const struct msgb *msg_rx, struct msgb 
**msg_tx)
+{
+       *msg_tx = NULL;
+
+       uint8_t *data = msgb_l2(msg_rx);
+       size_t data_len = msgb_l2len(msg_rx);
+       int rc = 0;
+
+       struct oap_message oap_msg = {0};
+
+       OSMO_ASSERT(data);
+
+       rc = oap_decode(data, data_len, &oap_msg);
+       if (rc < 0) {
+               LOGP(DGPRS, LOGL_ERROR,
+                    "Decoding OAP message failed with error '%s' (%d)\n",
+                    get_value_string(gsm48_gmm_cause_names, -rc), -rc);
+               return -10;
+       }
+
+       switch (oap_msg.message_type) {
+       case OAP_MSGT_CHALLENGE_REQUEST:
+               return handle_challenge(state, &oap_msg, msg_tx);
+
+       case OAP_MSGT_REGISTER_RESULT:
+               // successfully registered!
+               state->state = OAP_REGISTERED;
+               break;
+
+       case OAP_MSGT_REGISTER_ERROR:
+               LOGP(DGPRS, LOGL_ERROR,
+                    "OAP registration failed\n");
+               state->state = OAP_INITIALIZED;
+               if (state->registration_failures < 3) {
+                       state->registration_failures ++;
+                       return oap_register(state, msg_tx);
+               }
+               return -11;
+
+       case OAP_MSGT_REGISTER_REQUEST:
+       case OAP_MSGT_CHALLENGE_RESULT:
+               LOGP(DGPRS, LOGL_ERROR,
+                    "Received invalid OAP message type for OAP client side: 
%d\n",
+                    (int)oap_msg.message_type);
+               return -12;
+
+       default:
+               LOGP(DGPRS, LOGL_ERROR,
+                    "Unknown OAP message type: %d\n",
+                    (int)oap_msg.message_type);
+               return -13;
+       }
+
+       return 0;
+}
diff --git a/openbsc/src/gprs/oap_messages.c b/openbsc/src/gprs/oap_messages.c
new file mode 100644
index 0000000..eb52053
--- /dev/null
+++ b/openbsc/src/gprs/oap_messages.c
@@ -0,0 +1,178 @@
+/* Osmocom Authentication Protocol message encoder/decoder */
+
+/* (C) 2015 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 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 <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <openbsc/oap_messages.h>
+
+#include <openbsc/debug.h>
+#include <openbsc/gprs_utils.h>
+#include <openbsc/utils.h>
+
+#include <osmocom/gsm/tlv.h>
+#include <osmocom/core/msgb.h>
+
+#include <stdint.h>
+
+
+int oap_decode(const uint8_t *const_data, size_t data_len,
+              struct oap_message *oap_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;
+
+       memset(oap_msg, 0, sizeof(*oap_msg));
+
+       /* message type */
+       rc = gprs_shift_v_fixed(&data, &data_len, 1, &value);
+       if (rc < 0)
+               return -GMM_CAUSE_INV_MAND_INFO;
+       oap_msg->message_type = decode_big_endian(value, 1);
+
+       /* specific parts */
+       while (data_len > 0) {
+               enum oap_iei iei;
+
+               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 OAP_CLIENT_ID_IE:
+                       if (value_len != 2) {
+                               LOGP(DGPRS, 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 = decode_big_endian(value, 
value_len);
+
+                       if (oap_msg->client_id == 0) {
+                               LOGP(DGPRS, 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(DGPRS, 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(DGPRS, 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(DGPRS, 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(DGPRS, 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(DGPRS, 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(DGPRS, LOGL_NOTICE,
+                            "OAP IE type %d unknown\n", iei);
+                       continue;
+               }
+       }
+
+       return 0;
+}
+
+void oap_encode(struct msgb *msg, const struct 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),
+                            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;
+}
+
-- 
2.1.4

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