refactor: move RESET Osmux TLV parsing to ran_msg_a.c

ran_peer.c is not the proper place to parse messages, because it should be RAN
agnostic. All parsing and encoding belongs in ran_msg_a.c and ran_msg_iu.c.

Move the Osmux TLV parsing into the is_reset_msg op: add supports_osmux
out-parameter (and add a logging fi pointer). To be able to modify msg->l3h,
also make the msgb arg non-const.

In ranap_is_reset_msg(), always return non-support for Osmux.

In bssmap_is_reset_msg(), return 0 if no TLVs were parsed, 1/-1 if an Osmux TLV
was present/not present.

Update the osmux support flag directly where the ConnectionLess message is
received, so that there is only one place responsible for that.

Related: OS#4595
Change-Id: I1ad4a3f9356216dd4bf8c48fba29fd23438810a7

3 files changed, 9 insertions, 4 deletions

diff --git a/include/osmocom/msc/ran_msg_a.h b/include/osmocom/msc/ran_msg_a.h
index 3ba081de2..2d045b96e 100644
--- a/include/osmocom/msc/ran_msg_a.h
+++ b/include/osmocom/msc/ran_msg_a.h
@@ -35,7 +35,8 @@ struct gsm_mncc_bearer_cap;
 int ran_a_decode_l2(struct ran_dec *ran_a, struct msgb *bssap);
 struct msgb *ran_a_encode(struct osmo_fsm_inst *caller_fi, const struct ran_msg *ran_enc_msg);
 
-enum reset_msg_type bssmap_is_reset_msg(const struct sccp_ran_inst *sri, const struct msgb *l2);
+enum reset_msg_type bssmap_is_reset_msg(const struct sccp_ran_inst *sri, struct osmo_fsm_inst *log_fi,
+					struct msgb *l2, int *supports_osmux);
 struct msgb *bssmap_make_reset_msg(const struct sccp_ran_inst *sri, enum reset_msg_type type);
 struct msgb *bssmap_make_paging_msg(const struct sccp_ran_inst *sri, const struct gsm0808_cell_id *page_cell_id,
 				    const char *imsi, uint32_t tmsi, enum paging_cause cause);
diff --git a/include/osmocom/msc/ran_msg_iu.h b/include/osmocom/msc/ran_msg_iu.h
index 316a91cdb..3f3d61e4a 100644
--- a/include/osmocom/msc/ran_msg_iu.h
+++ b/include/osmocom/msc/ran_msg_iu.h
@@ -28,7 +28,8 @@
 int ran_iu_decode_l2(struct ran_dec *ran_dec_iu, struct msgb *ranap);
 struct msgb *ran_iu_encode(struct osmo_fsm_inst *caller_fi, const struct ran_msg *ran_enc_msg);
 
-enum reset_msg_type ranap_is_reset_msg(const struct sccp_ran_inst *sri, const struct msgb *l2);
+enum reset_msg_type ranap_is_reset_msg(const struct sccp_ran_inst *sri, struct osmo_fsm_inst *log_fi,
+				       struct msgb *l2, int *supports_osmux);
 struct msgb *ranap_make_reset_msg(const struct sccp_ran_inst *sri, enum reset_msg_type type);
 struct msgb *ranap_make_paging_msg(const struct sccp_ran_inst *sri, const struct gsm0808_cell_id *page_cell_id,
 				   const char *imsi, uint32_t tmsi, enum paging_cause cause);
diff --git a/include/osmocom/msc/sccp_ran.h b/include/osmocom/msc/sccp_ran.h
index f84bf614e..a4bd4ca61 100644
--- a/include/osmocom/msc/sccp_ran.h
+++ b/include/osmocom/msc/sccp_ran.h
@@ -233,8 +233,11 @@ struct sccp_ran_ops {
 
 	/* Return whether the given l2_cl message is a RESET, RESET ACKNOWLEDGE, or RESET-unrelated message.
 	 * This callback is stored in struct sccp_ran_inst to provide RESET handling to the caller (ran_peer),
-	 * it is not used in sccp_ran.c. */
-	enum reset_msg_type (* is_reset_msg )(const struct sccp_ran_inst *sri, const struct msgb *l2_cl);
+	 * it is not used in sccp_ran.c.
+	 * In supports_osmux, return 0 for no information, 1 for support detected, -1 for non-support detected.
+	 */
+	enum reset_msg_type (* is_reset_msg )(const struct sccp_ran_inst *sri, struct osmo_fsm_inst *log_fi,
+					      struct msgb *l2_cl, int *supports_osmux);
 
 	/* Return a RESET or RESET ACK message for this RAN type.
 	 * This callback is stored in struct sccp_ran_inst to provide RESET handling to the caller (ran_peer),