1 files changed, 281 insertions, 0 deletions
diff --git a/include/osmocom/msc/ran_msg.h b/include/osmocom/msc/ran_msg.h
new file mode 100644
index 000000000..4d0485d43
--- /dev/null
+++ b/include/osmocom/msc/ran_msg.h
@@ -0,0 +1,281 @@
+/* API to forward upcoming NAS events, e.g. from BSSAP and RANAP, to be handled by MSC-A or MSC-I. */
+/*
+ * (C) 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * Author: Neels Hofmeyr <neels@hofmeyr.de>
+ *
+ * All Rights Reserved
+ *
+ * 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 <osmocom/core/utils.h>
+#include <osmocom/core/fsm.h>
+#include <osmocom/core/sockaddr_str.h>
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/mgcp_client/mgcp_client.h>
+
+#include <osmocom/msc/msc_common.h>
+
+struct msgb;
+struct osmo_fsm_inst;
+
+#define LOG_RAN_DEC(NAS_DEC, subsys, level, fmt, args...) \
+	LOGPFSMSL((NAS_DEC)? (NAS_DEC)->caller_fi : NULL, subsys, level, "RAN decode: " fmt, ## args)
+
+#define LOG_RAN_ENC(FI, subsys, level, fmt, args...) \
+	LOGPFSMSL(FI, subsys, level, "RAN encode: " fmt, ## args)
+
+/* These message types are named after the BSSAP procedures in nas_a.h; most are also used for RANAP procedures of
+ * similar meaning in nas_iu.h. */
+enum ran_msg_type {
+	RAN_MSG_NONE = 0,
+	RAN_MSG_COMPL_L3,
+	RAN_MSG_DTAP,
+	RAN_MSG_CLEAR_COMMAND,
+	RAN_MSG_CLEAR_REQUEST,
+	RAN_MSG_CLEAR_COMPLETE,
+	RAN_MSG_CLASSMARK_REQUEST,
+	RAN_MSG_CLASSMARK_UPDATE,
+	RAN_MSG_CIPHER_MODE_COMMAND,
+	RAN_MSG_CIPHER_MODE_COMPLETE,
+	RAN_MSG_CIPHER_MODE_REJECT,
+	RAN_MSG_COMMON_ID,
+	RAN_MSG_ASSIGNMENT_COMMAND,
+	RAN_MSG_ASSIGNMENT_COMPLETE,
+	RAN_MSG_ASSIGNMENT_FAILURE,
+	RAN_MSG_SAPI_N_REJECT,
+	RAN_MSG_LCLS_STATUS,
+	RAN_MSG_LCLS_BREAK_REQ,
+	RAN_MSG_HANDOVER_COMMAND,
+	RAN_MSG_HANDOVER_PERFORMED,
+	RAN_MSG_HANDOVER_REQUIRED,
+	RAN_MSG_HANDOVER_REQUIRED_REJECT,
+	RAN_MSG_HANDOVER_REQUEST,
+	RAN_MSG_HANDOVER_REQUEST_ACK,
+	RAN_MSG_HANDOVER_DETECT,
+	RAN_MSG_HANDOVER_SUCCEEDED,
+	RAN_MSG_HANDOVER_COMPLETE,
+	RAN_MSG_HANDOVER_FAILURE,
+};
+
+extern const struct value_string ran_msg_type_names[];
+static inline const char *ran_msg_type_name(enum ran_msg_type val)
+{ return get_value_string(ran_msg_type_names, val); }
+
+struct ran_clear_command {
+	enum gsm0808_cause gsm0808_cause;
+	bool csfb_ind;
+};
+
+struct ran_assignment_command {
+	const struct osmo_sockaddr_str *cn_rtp;
+	const struct gsm0808_channel_type *channel_type;
+	enum nsap_addr_enc rab_assign_addr_enc;
+};
+
+struct ran_cipher_mode_command {
+	const struct osmo_auth_vector *vec;
+	const struct osmo_gsm48_classmark *classmark;
+	struct {
+		bool umts_aka;
+		bool retrieve_imeisv;
+		uint8_t a5_encryption_mask;
+
+		/* out-argument to return the key to the caller, pass NULL if not needed. */
+		struct geran_encr *chosen_key;
+	} geran;
+};
+
+struct ran_handover_request {
+	const char *imsi;
+	const struct osmo_gsm48_classmark *classmark;
+	/* A Handover Request on GERAN-A sends separate IEs for
+	 * - permitted algorithms, here composed from the a5_encryption_mask,
+	 * - the key, here taken from chosen_encryption->key iff chosen_encryption is present,
+	 * - the actually chosen algorithm ("Serving"), here taken from chosen_encryption->alg_id.
+	 */
+	struct {
+		struct gsm0808_channel_type *channel_type;
+		uint8_t a5_encryption_mask;
+		/*! chosen_encryption->alg_id is in encoded format:
+		 * alg_id == 1 means A5/0 i.e. no encryption, alg_id == 4 means A5/3.
+		 * alg_id == 0 means no such IE was present. */
+		struct geran_encr *chosen_encryption;
+	} geran;
+	struct gsm0808_cell_id cell_id_serving;
+	struct gsm0808_cell_id cell_id_target;
+
+	enum gsm0808_cause bssap_cause;
+
+	bool current_channel_type_1_present;
+	uint8_t current_channel_type_1;
+
+	enum gsm0808_permitted_speech speech_version_used;
+
+	const uint8_t *old_bss_to_new_bss_info_raw;
+	uint8_t old_bss_to_new_bss_info_raw_len;
+
+	struct osmo_sockaddr_str *rtp_ran_local;
+
+	struct gsm0808_speech_codec_list *codec_list_msc_preferred;
+
+	bool call_id_present;
+	uint32_t call_id;
+
+	const uint8_t *global_call_reference;
+	uint8_t global_call_reference_len;
+};
+
+struct ran_handover_request_ack {
+	const uint8_t *rr_ho_command;
+	uint8_t rr_ho_command_len;
+	bool chosen_channel_present;
+	uint8_t chosen_channel;
+	/*! chosen_encr_alg is in encoded format:
+	 * chosen_encr_alg == 1 means A5/0 i.e. no encryption, chosen_encr_alg == 4 means A5/3.
+	 * chosen_encr_alg == 0 means no such IE was present. */
+	uint8_t chosen_encr_alg;
+
+	/* chosen_speech_version == 0 means "not present" */
+	enum gsm0808_permitted_speech chosen_speech_version;
+
+	struct osmo_sockaddr_str remote_rtp;
+	bool codec_present;
+	enum mgcp_codecs codec;
+};
+
+struct ran_handover_command {
+	const uint8_t *rr_ho_command;
+	uint8_t rr_ho_command_len;
+
+	const uint8_t *new_bss_to_old_bss_info_raw;
+	uint8_t new_bss_to_old_bss_info_raw_len;
+};
+
+struct ran_handover_required {
+	uint16_t cause;
+	struct gsm0808_cell_id_list2 cil;
+
+	bool current_channel_type_1_present;
+	/*! See gsm0808_chosen_channel() */
+	uint8_t current_channel_type_1;
+
+	enum gsm0808_permitted_speech speech_version_used;
+
+	uint8_t *old_bss_to_new_bss_info_raw;
+	size_t old_bss_to_new_bss_info_raw_len;
+};
+
+struct ran_msg {
+	enum ran_msg_type msg_type;
+
+	/* Since different RAN implementations feed these messages, they should place here an implementation specific
+	 * string constant to name the actual message (e.g. "BSSMAP Assignment Complete" vs. "RANAP RAB Assignment
+	 * Response") */
+	const char *msg_name;
+
+	union {
+		struct {
+			const struct gsm0808_cell_id *cell_id;
+			struct msgb *msg;
+		} compl_l3;
+		struct msgb *dtap;
+		struct {
+			enum gsm0808_cause bssap_cause;
+#define RAN_MSG_BSSAP_CAUSE_UNSET 0xffff
+		} clear_request;
+		struct ran_clear_command clear_command;
+		struct {
+			const struct osmo_gsm48_classmark *classmark;
+		} classmark_update;
+		struct ran_cipher_mode_command cipher_mode_command;
+		struct {
+			/*! alg_id is in encoded format:
+			 * alg_id == 1 means A5/0 i.e. no encryption, alg_id == 4 means A5/3.
+			 * alg_id == 0 means no such IE was present. */
+			uint8_t alg_id;
+			const char *imeisv;
+		} cipher_mode_complete;
+		struct {
+			enum gsm0808_cause bssap_cause;
+		} cipher_mode_reject;
+		struct {
+			const char *imsi;
+		} common_id;
+		struct {
+			enum gsm48_reject_value cause;
+		} cm_service_reject;
+		struct ran_assignment_command assignment_command;
+		struct {
+			struct osmo_sockaddr_str remote_rtp;
+			bool codec_present;
+			enum mgcp_codecs codec;
+		} assignment_complete;
+		struct {
+			enum gsm0808_cause bssap_cause;
+			uint8_t rr_cause;
+			const struct gsm0808_speech_codec_list *scl_bss_supported;
+		} assignment_failure;
+		struct {
+			enum gsm0808_cause bssap_cause;
+			uint8_t dlci;
+		} sapi_n_reject;
+		struct {
+			enum gsm0808_lcls_status status;
+		} lcls_status;
+		struct {
+			int todo;
+		} lcls_break_req;
+		struct ran_handover_required handover_required;
+		struct gsm0808_handover_required_reject handover_required_reject;
+		struct ran_handover_command handover_command;
+		struct {
+			enum gsm0808_cause cause;
+		} handover_failure;
+		struct ran_handover_request handover_request;
+		struct ran_handover_request_ack handover_request_ack;
+	};
+};
+
+/* MSC-A/I/T roles implement this to receive decoded NAS messages, upon feeding an L2 msgb to a ran_dec_l2_t matching the
+ * RAN type implementation. */
+typedef int (* ran_decode_cb_t )(struct osmo_fsm_inst *caller_fi, void *caller_data, const struct ran_msg *msg);
+
+struct ran_dec {
+	/* caller provided osmo_fsm_inst, used both for logging from within decoding of NAS events, as well as caller's
+	 * context in decode_cb(). */
+	struct osmo_fsm_inst *caller_fi;
+	void *caller_data;
+
+	/* Callback receives the decoded NAS messages */
+	ran_decode_cb_t decode_cb;
+};
+
+/* NAS decoders (BSSAP/RANAP) implement this to turn a msgb into a struct ran_msg.
+ * An implementation typically calls ran_decoded() when done decoding.
+ * NAS decoding is modeled with a callback instead of a plain decoding, because some L2 messages by design contain more
+ * than one NAS event, e.g. Ciphering Mode Complete may include another L3 message for Identity Response, and LCLS
+ * Information messages can contain Status and Break Req events. */
+typedef int (* ran_dec_l2_t )(struct ran_dec *ran_dec, struct msgb *l2);
+
+int ran_decoded(struct ran_dec *ran_dec, struct ran_msg *msg);
+
+/* An MSC-A/I/T role that receives NAS events containing DTAP buffers may use this to detect DTAP duplicates as in TS
+ * 24.007 11.2.3.2 Message Type Octet / Duplicate Detection */
+bool ran_dec_dtap_undup_is_duplicate(struct osmo_fsm_inst *log_fi, uint8_t *n_sd_next, bool is_r99, struct msgb *l3);
+
+/* Implemented by individual RAN implementations, see ran_a_encode() and ran_iu_encode(). */
+typedef struct msgb *(* ran_encode_t )(struct osmo_fsm_inst *caller_fi, const struct ran_msg *ran_enc_msg);