libmsc: duplicate gsm0808 / gsm48 functions (towards BSC)

In osmo-nitb, libmsc would directly call the functions on the BSC level, not
always via the bsc_api. When separating libmsc from libbsc, some functions are
missing from the linkage.

Hence duplicate these functions to libmsc, add an msc_ prefix for clarity, also
add a _tx to gsm0808_cipher_mode():

* add msc_gsm0808_tx_cipher_mode() (dummy/stub)
* add msc_gsm48_tx_mm_serv_ack()
* add msc_gsm48_tx_mm_serv_rej()

Call these from libmsc instead of

* gsm0808_cipher_mode()
* gsm48_tx_mm_serv_ack()
* gsm48_tx_mm_serv_rej()

Also add a comment relatd to msc_gsm0808_tx_cipher_mode() in two places.

Change-Id: I5b276853d3af71f5e3f0a031fd17b4fff0580020

4 files changed, 68 insertions, 13 deletions

diff --git a/openbsc/include/openbsc/msc_ifaces.h b/openbsc/include/openbsc/msc_ifaces.h
index cd0039c6f..83aad92a4 100644
--- a/openbsc/include/openbsc/msc_ifaces.h
+++ b/openbsc/include/openbsc/msc_ifaces.h
@@ -37,3 +37,11 @@ extern int a_tx(struct msgb *msg);
 
 int msc_tx_dtap(struct gsm_subscriber_connection *conn,
 		struct msgb *msg);
+
+int msc_gsm48_tx_mm_serv_ack(struct gsm_subscriber_connection *conn);
+int msc_gsm48_tx_mm_serv_rej(struct gsm_subscriber_connection *conn,
+			     enum gsm48_reject_value value);
+
+/* TODO: specific to A interface, move this away */
+int msc_gsm0808_tx_cipher_mode(struct gsm_subscriber_connection *conn, int cipher,
+			       const uint8_t *key, int len, int include_imeisv);
diff --git a/openbsc/src/libmsc/a_iface.c b/openbsc/src/libmsc/a_iface.c
index 0eaeef188..1f471f97b 100644
--- a/openbsc/src/libmsc/a_iface.c
+++ b/openbsc/src/libmsc/a_iface.c
@@ -22,6 +22,9 @@
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/logging.h>
 
+#include <openbsc/debug.h>
+
+#include <openbsc/gsm_data.h>
 #include <openbsc/msc_ifaces.h>
 #include <openbsc/debug.h>
 
@@ -31,3 +34,12 @@ int a_tx(struct msgb *msg)
 	     " not implemented.\n%s\n", osmo_hexdump(msg->data, msg->len));
 	return -1;
 }
+
+int msc_gsm0808_tx_cipher_mode(struct gsm_subscriber_connection *conn, int cipher,
+			       const uint8_t *key, int len, int include_imeisv)
+{
+	/* TODO generalize for A- and Iu interfaces, don't name after 08.08 */
+	LOGP(DMSC, LOGL_ERROR, "gsm0808_cipher_mode(): message to be sent to"
+	     " BSC, but A interface not yet implemented.\n");
+	return -1;
+}
diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c
index a6559a846..62b18da84 100644
--- a/openbsc/src/libmsc/gsm_04_08.c
+++ b/openbsc/src/libmsc/gsm_04_08.c
@@ -58,6 +58,7 @@
 #include <openbsc/mncc_int.h>
 #include <osmocom/abis/e1_input.h>
 #include <osmocom/core/bitvec.h>
+#include <openbsc/msc_ifaces.h>
 
 #include <osmocom/gsm/gsm48.h>
 #include <osmocom/gsm/gsm0480.h>
@@ -228,8 +229,9 @@ int gsm48_secure_channel(struct gsm_subscriber_connection *conn, int key_seq,
 					    op->atuple.key_seq);
 	} else if (rc == AUTH_DO_CIPH) {
 		/* Start ciphering directly */
-		return gsm0808_cipher_mode(conn, net->a5_encryption,
-		                           op->atuple.vec.kc, 8, 0);
+		/* TODO: specific to A interface, move this away */
+		return msc_gsm0808_tx_cipher_mode(conn, net->a5_encryption,
+						  op->atuple.vec.kc, 8, 0);
 	}
 
 	return -EINVAL; /* not reached */
@@ -926,7 +928,7 @@ static int _gsm48_rx_mm_serv_req_sec_cb(
 
 		case GSM_SECURITY_NOAVAIL:
 		case GSM_SECURITY_ALREADY:
-			rc = gsm48_tx_mm_serv_ack(conn);
+			rc = msc_gsm48_tx_mm_serv_ack(conn);
 			implit_attach(conn);
 			break;
 
@@ -971,14 +973,14 @@ static int gsm48_rx_mm_serv_req(struct gsm_subscriber_connection *conn, struct m
 	DEBUGP(DMM, "<- CM SERVICE REQUEST ");
 	if (msg->data_len < sizeof(struct gsm48_service_request*)) {
 		DEBUGPC(DMM, "wrong sized message\n");
-		return gsm48_tx_mm_serv_rej(conn,
-					    GSM48_REJECT_INCORRECT_MESSAGE);
+		return msc_gsm48_tx_mm_serv_rej(conn,
+						GSM48_REJECT_INCORRECT_MESSAGE);
 	}
 
 	if (msg->data_len < req->mi_len + 6) {
 		DEBUGPC(DMM, "does not fit in packet\n");
-		return gsm48_tx_mm_serv_rej(conn,
-					    GSM48_REJECT_INCORRECT_MESSAGE);
+		return msc_gsm48_tx_mm_serv_rej(conn,
+						GSM48_REJECT_INCORRECT_MESSAGE);
 	}
 
 	gsm48_mi_to_string(mi_string, sizeof(mi_string), mi, mi_len);
@@ -998,8 +1000,8 @@ static int gsm48_rx_mm_serv_req(struct gsm_subscriber_connection *conn, struct m
 				tmsi_from_string(mi_string));
 	} else {
 		DEBUGPC(DMM, "mi_type is not expected: %d\n", mi_type);
-		return gsm48_tx_mm_serv_rej(conn,
-					    GSM48_REJECT_INCORRECT_MESSAGE);
+		return msc_gsm48_tx_mm_serv_rej(conn,
+						GSM48_REJECT_INCORRECT_MESSAGE);
 	}
 
 	osmo_signal_dispatch(SS_SUBSCR, S_SUBSCR_IDENTITY, (classmark2 + classmark2_len));
@@ -1013,8 +1015,8 @@ static int gsm48_rx_mm_serv_req(struct gsm_subscriber_connection *conn, struct m
 
 	/* FIXME: if we don't know the TMSI, inquire abit IMSI and allocate new TMSI */
 	if (!subscr)
-		return gsm48_tx_mm_serv_rej(conn,
-					    GSM48_REJECT_IMSI_UNKNOWN_IN_VLR);
+		return msc_gsm48_tx_mm_serv_rej(conn,
+						GSM48_REJECT_IMSI_UNKNOWN_IN_VLR);
 
 	if (!conn->subscr)
 		conn->subscr = subscr;
@@ -1248,8 +1250,9 @@ static int gsm48_rx_mm_auth_resp(struct gsm_subscriber_connection *conn, struct
 	DEBUGPC(DMM, "OK\n");
 
 	/* Start ciphering */
-	return gsm0808_cipher_mode(conn, net->a5_encryption,
-	                           conn->sec_operation->atuple.vec.kc, 8, 0);
+	return msc_gsm0808_tx_cipher_mode(conn, net->a5_encryption,
+					  conn->sec_operation->atuple.vec.kc,
+					  8, 0);
 }
 
 static int gsm48_rx_mm_auth_fail(struct gsm_subscriber_connection *conn, struct msgb *msg)
diff --git a/openbsc/src/libmsc/msc_ifaces.c b/openbsc/src/libmsc/msc_ifaces.c
index 234ffd2ab..bc8533b5a 100644
--- a/openbsc/src/libmsc/msc_ifaces.c
+++ b/openbsc/src/libmsc/msc_ifaces.c
@@ -49,3 +49,35 @@ int msc_tx_dtap(struct gsm_subscriber_connection *conn,
 {
 	return msc_tx(conn, msg);
 }
+
+
+/* 9.2.5 CM service accept */
+int msc_gsm48_tx_mm_serv_ack(struct gsm_subscriber_connection *conn)
+{
+	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 SERV ACC");
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
+
+	gh->proto_discr = GSM48_PDISC_MM;
+	gh->msg_type = GSM48_MT_MM_CM_SERV_ACC;
+
+	DEBUGP(DMM, "-> CM SERVICE ACCEPT\n");
+
+	return msc_tx_dtap(conn, msg);
+}
+
+/* 9.2.6 CM service reject */
+int msc_gsm48_tx_mm_serv_rej(struct gsm_subscriber_connection *conn,
+			     enum gsm48_reject_value value)
+{
+	struct msgb *msg;
+
+	msg = gsm48_create_mm_serv_rej(value);
+	if (!msg) {
+		LOGP(DMM, LOGL_ERROR, "Failed to allocate CM Service Reject.\n");
+		return -1;
+	}
+
+	DEBUGP(DMM, "-> CM SERVICE Reject cause: %d\n", value);
+
+	return msc_tx_dtap(conn, msg);
+}