gsup_client: Add new APIs to avoid users accessing struct fields

This is a first step towards changing gsup_client implementation to use
an osmo_stream_cli instead of libosmo-abis' ipa_client_conn.
The libosmo-abis' ipa_client_conn will eventually be deprecated together
with all IPA related code in libosmo-abis.

In order to be able to make the implementation change, we first need to
make sure no users are using the struct fields of gsup_client (this
patch); 2nd step will be making the struct private by moving it to a
private header; 3rd step will be changing the implementation to use
osmo_stream.

Related: OS#5896
Change-Id: I401af83232022f1c141eef1f428cbe206a8aaaa2

TODO-RELEASE

@@ -7,3 +7,6 @@
 # If any interfaces have been added since the last public release: c:r:a + 1.
 # If any interfaces have been removed or changed since the last public release: c:r:0.
 #library	what			description / commit summary line
+libosmo-gsup-client new API osmo_gsup_client_{get,set}_data(),
+                            osmo_gsup_client_get_rem_addr(), osmo_gsup_client_get_rem_port(),
+                            osmo_gsup_client_is_connected(), osmo_gsup_client_get_ipaccess_unit()

include/osmocom/gsupclient/gsup_client.h

@@ -20,6 +20,9 @@
  */
 #pragma once
 
+#include <stdint.h>
+#include <stdbool.h>
+
 #include <osmocom/core/timer.h>
 #include <osmocom/gsm/oap_client.h>
 #include <osmocom/gsm/ipa.h>
@@ -40,6 +43,7 @@ typedef int (*osmo_gsup_client_read_cb_t)(struct osmo_gsup_client *gsupc, struct
 
 typedef bool (*osmo_gsup_client_up_down_cb_t)(struct osmo_gsup_client *gsupc, bool up);
 
+/* NOTE: THIS STRUCT IS CONSIDERED PRIVATE, AVOID ACCESSING ITS FIELDS! */
 struct osmo_gsup_client {
 	const char *unit_name; /* same as ipa_dev->unit_name, for backwards compat */
 
@@ -99,3 +103,12 @@ int osmo_gsup_client_enc_send(struct osmo_gsup_client *gsupc,
 			      const struct osmo_gsup_message *gsup_msg);
 struct msgb *osmo_gsup_client_msgb_alloc(void);
 
+void *osmo_gsup_client_get_data(const struct osmo_gsup_client *gsupc);
+void osmo_gsup_client_set_data(struct osmo_gsup_client *gsupc, void *data);
+
+const char *osmo_gsup_client_get_rem_addr(const struct osmo_gsup_client *gsupc);
+uint16_t osmo_gsup_client_get_rem_port(const struct osmo_gsup_client *gsupc);
+
+bool osmo_gsup_client_is_connected(const struct osmo_gsup_client *gsupc);
+const struct ipaccess_unit *osmo_gsup_client_get_ipaccess_unit(const struct osmo_gsup_client *gsupc);
+

src/gsupclient/gsup_client.c

@@ -450,3 +450,36 @@ struct msgb *osmo_gsup_client_msgb_alloc(void)
 {
 	return msgb_alloc_headroom(4000, 64, __func__);
 }
+
+void *osmo_gsup_client_get_data(const struct osmo_gsup_client *gsupc)
+{
+	return gsupc->data;
+}
+
+void osmo_gsup_client_set_data(struct osmo_gsup_client *gsupc, void *data)
+{
+	gsupc->data = data;
+}
+
+const char *osmo_gsup_client_get_rem_addr(const struct osmo_gsup_client *gsupc)
+{
+	if (!gsupc->link)
+		return NULL;
+	return gsupc->link->addr;
+}
+uint16_t osmo_gsup_client_get_rem_port(const struct osmo_gsup_client *gsupc)
+{
+	if (!gsupc->link)
+		return 0;
+	return gsupc->link->port;
+}
+
+bool osmo_gsup_client_is_connected(const struct osmo_gsup_client *gsupc)
+{
+	return gsupc->is_connected;
+}
+
+const struct ipaccess_unit *osmo_gsup_client_get_ipaccess_unit(const struct osmo_gsup_client *gsupc)
+{
+	return gsupc->ipa_dev;
+}

src/gsupclient/gsup_client_mux.c

@@ -58,7 +58,7 @@ static enum osmo_gsup_message_class gsup_client_mux_classify(struct gsup_client_
 /* Non-static for unit tests */
 int gsup_client_mux_rx(struct osmo_gsup_client *gsup_client, struct msgb *msg)
 {
-	struct gsup_client_mux *gcm = gsup_client->data;
+	struct gsup_client_mux *gcm = osmo_gsup_client_get_data(gsup_client);
 	struct osmo_gsup_message gsup;
 	enum osmo_gsup_message_class message_class;
 	int rc;
@@ -115,7 +115,7 @@ int gsup_client_mux_start(struct gsup_client_mux *gcm, const char *gsup_server_a
 						    &gsup_client_mux_rx, NULL);
 	if (!gcm->gsup_client)
 		return -ENOMEM;
-	gcm->gsup_client->data = gcm;
+	osmo_gsup_client_set_data(gcm->gsup_client, gcm);
 	return 0;
 }
 
@@ -144,14 +144,16 @@ void gsup_client_mux_tx_set_source(const struct gsup_client_mux *gcm,
 				   struct osmo_gsup_message *gsup_msg)
 {
 	const char *local_msc_name;
+	const struct ipaccess_unit *ipa_dev;
 
 	if (!gcm)
 		return;
 	if (!gcm->gsup_client)
 		return;
-	if (!gcm->gsup_client->ipa_dev)
+	ipa_dev = osmo_gsup_client_get_ipaccess_unit(gcm->gsup_client);
+	if (!ipa_dev)
 		return;
-	local_msc_name = gcm->gsup_client->ipa_dev->serno;
+	local_msc_name = ipa_dev->serno;
 	if (!local_msc_name)
 		return;
 	gsup_msg->source_name = (const uint8_t *) local_msc_name;

src/remote_hlr.c

@@ -66,7 +66,7 @@ static void remote_hlr_err_reply(struct remote_hlr *rh, const struct osmo_gsup_m
  * The local MSC shall be indicated by gsup.destination_name. */
 static int remote_hlr_rx(struct osmo_gsup_client *gsupc, struct msgb *msg)
 {
-	struct remote_hlr *rh = gsupc->data;
+	struct remote_hlr *rh = osmo_gsup_client_get_data(gsupc);
 	struct proxy_subscr proxy_subscr;
 	struct osmo_gsup_message gsup;
 	int rc;
@@ -108,7 +108,7 @@ struct remote_hlr_pending_up {
 
 static bool remote_hlr_up_down(struct osmo_gsup_client *gsupc, bool up)
 {
-	struct remote_hlr *remote_hlr = gsupc->data;
+	struct remote_hlr *remote_hlr = osmo_gsup_client_get_data(gsupc);
 	struct remote_hlr_pending_up *p, *n;
 	if (!up) {
 		LOG_REMOTE_HLR(remote_hlr, LOGL_NOTICE, "link to remote HLR is down, removing GSUP client\n");
@@ -127,7 +127,7 @@ static bool remote_hlr_up_down(struct osmo_gsup_client *gsupc, bool up)
 
 bool remote_hlr_is_up(struct remote_hlr *remote_hlr)
 {
-	return remote_hlr && remote_hlr->gsupc && remote_hlr->gsupc->is_connected;
+	return remote_hlr && remote_hlr->gsupc && osmo_gsup_client_is_connected(remote_hlr->gsupc);
 }
 
 struct remote_hlr *remote_hlr_get_or_connect(const struct osmo_sockaddr_str *addr, bool connect,
@@ -180,7 +180,7 @@ struct remote_hlr *remote_hlr_get_or_connect(const struct osmo_sockaddr_str *add
 		return NULL;
 	}
 
-	rh->gsupc->data = rh;
+	osmo_gsup_client_set_data(rh->gsupc, rh);
 	llist_add(&rh->entry, &remote_hlrs);
 
 add_result_cb: