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

1 files changed, 32 insertions, 0 deletions

diff --git a/openbsc/src/libmsc/msc_ifaces.c b/openbsc/src/libmsc/msc_ifaces.c
index 160c90b95..500c99c2e 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);
+}