oap: implement initial OAP API.

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

Sponsored-by: On-Waves ehf

3 files changed, 150 insertions, 1 deletions

diff --git a/openbsc/include/openbsc/Makefile.am b/openbsc/include/openbsc/Makefile.am
index 828f5bd2d..8a074c244 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 000000000..2370cbe07
--- /dev/null
+++ b/openbsc/include/openbsc/oap.h
@@ -0,0 +1,78 @@
+/* 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,	/* enabled, config is 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.)
+ * About the name: the idea is do_something(oap_encoded(my_struct)) */
+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 000000000..a7a254c2e
--- /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);
+