libosmogsm: (re)introduce gsm48_push_l3hdr()

There was gsm0480_l3hdr_push() declared in a header file, but
not exposed in 'libosmogsm.map'. Furthermore, for some reason
it was a part of GSM 04.80 API, what is not actually correct.

Let's rename this symbol, and properly expose it as a part of
the GSM 04.08 API. Also, let's introduce an auxiliary wrapper
for messages, where the transaction identifier is required
(see GSM 04.07, section 11.2.3.1.2).

Change-Id: I8a045efe8335d83fcbe8d43eb180972e3b1d9dda

4 files changed, 38 insertions, 21 deletions

diff --git a/src/gsm/gsm0411_utils.c b/src/gsm/gsm0411_utils.c
index 53d37a43..ccefe546 100644
--- a/src/gsm/gsm0411_utils.c
+++ b/src/gsm/gsm0411_utils.c
@@ -35,7 +35,6 @@
 #include <osmocom/core/logging.h>
 
 #include <osmocom/gsm/gsm48.h>
-#include <osmocom/gsm/gsm0480.h>
 #include <osmocom/gsm/gsm_utils.h>
 #include <osmocom/gsm/protocol/gsm_03_40.h>
 #include <osmocom/gsm/protocol/gsm_04_11.h>
@@ -354,7 +353,7 @@ int gsm411_push_cp_header(struct msgb *msg, uint8_t proto, uint8_t trans,
 			     uint8_t msg_type)
 {
 	/* Outgoing proto_discr needs the highest bit set */
-	gsm0480_l3hdr_push(msg, proto | (trans << 4), msg_type);
+	gsm48_push_l3hdr_tid(msg, proto, trans, msg_type);
 	return 0;
 }
 
diff --git a/src/gsm/gsm0480.c b/src/gsm/gsm0480.c
index df640b8e..7756ecba 100644
--- a/src/gsm/gsm0480.c
+++ b/src/gsm/gsm0480.c
@@ -25,6 +25,7 @@
  *
  */
 
+#include <osmocom/gsm/gsm48.h>
 #include <osmocom/gsm/gsm0480.h>
 #include <osmocom/gsm/gsm_utils.h>
 
@@ -863,10 +864,11 @@ struct msgb *gsm0480_create_ussd_resp(uint8_t invoke_id, uint8_t trans_id, const
 	msgb_wrap_with_TL(msg, GSM0480_IE_FACILITY);
 
 	/* And finally pre-pend the L3 header */
-	gsm0480_l3hdr_push(msg,
-			   GSM48_PDISC_NC_SS | trans_id
-			   | (1<<7) /* TI direction = 1 */,
-			   GSM0480_MTYPE_RELEASE_COMPLETE);
+	gsm48_push_l3hdr_tid(msg, GSM48_PDISC_NC_SS,
+			     /* FIXME: TI direction is always 1 ?!? */
+			     trans_id | (1 << 7),
+			     GSM0480_MTYPE_RELEASE_COMPLETE);
+
 	return msg;
 }
 
@@ -932,17 +934,6 @@ struct msgb *gsm0480_gen_reject(int invoke_id, uint8_t problem_tag, uint8_t prob
 	return msg;
 }
 
-
-struct gsm48_hdr *gsm0480_l3hdr_push(struct msgb *msg, uint8_t proto_discr,
-				     uint8_t msg_type)
-{
-	struct gsm48_hdr *gh;
-	gh = (struct gsm48_hdr *) msgb_push(msg, sizeof(*gh));
-	gh->proto_discr = proto_discr;
-	gh->msg_type = msg_type;
-	return gh;
-}
-
 struct msgb *gsm0480_create_ussd_notify(int level, const char *text)
 {
 	struct msgb *msg;
@@ -954,7 +945,11 @@ struct msgb *gsm0480_create_ussd_notify(int level, const char *text)
 	gsm0480_wrap_invoke(msg, GSM0480_OP_CODE_USS_NOTIFY, 0);
 	gsm0480_wrap_facility(msg);
 
-	gsm0480_l3hdr_push(msg, GSM48_PDISC_NC_SS, GSM0480_MTYPE_REGISTER);
+	/* And finally pre-pend the L3 header */
+	gsm48_push_l3hdr(msg, GSM48_PDISC_NC_SS,
+			 /* FIXME: no transactionID?!? */
+			 GSM0480_MTYPE_REGISTER);
+
 	return msg;
 }
 
@@ -966,8 +961,10 @@ struct msgb *gsm0480_create_ussd_release_complete(void)
 	if (!msg)
 		return NULL;
 
-	/* FIXME: should this set trans_id and TI direction flag? */
-	gsm0480_l3hdr_push(msg, GSM48_PDISC_NC_SS,
-			   GSM0480_MTYPE_RELEASE_COMPLETE);
+	/* And finally pre-pend the L3 header */
+	gsm48_push_l3hdr(msg, GSM48_PDISC_NC_SS,
+			 /* FIXME: no transactionID?!? */
+			 GSM0480_MTYPE_RELEASE_COMPLETE);
+
 	return msg;
 }
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index b4892dea..136b9375 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -1024,4 +1024,24 @@ const struct value_string gsm48_reject_value_names[] = {
 	 { 0, NULL }
 };
 
+/*! Wrap a given \ref msg with \ref gsm48_hdr structure
+ * \param[out] msg      A message to be wrapped
+ * \param[in]  pdisc    GSM TS 04.07 protocol discriminator 1/2,
+ *                      sub-pdisc, trans_id or skip_ind 1/2,
+ *                      see section 11.2.3.1 for details
+ * \param[in]  msg_type GSM TS 04.08 message type
+ * @return              pointer to pushed header within \ref msg
+ */
+struct gsm48_hdr *gsm48_push_l3hdr(struct msgb *msg,
+				   uint8_t pdisc, uint8_t msg_type)
+{
+	struct gsm48_hdr *gh;
+
+	gh = (struct gsm48_hdr *) msgb_push(msg, sizeof(*gh));
+	gh->proto_discr = pdisc;
+	gh->msg_type = msg_type;
+
+	return gh;
+}
+
 /*! @} */
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 2bb9d97c..1da398c1 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -241,6 +241,7 @@ gsm411_rp_state_names;
 
 gsm414_msgt_names;
 
+gsm48_push_l3hdr;
 gsm48_att_tlvdef;
 gsm48_cc_msg_name;
 gsm48_rr_msg_name;