ensure valid primary_pc in osmo_ss7_instance

Initialize osmo_ss7_instance.cfg.primary_pc = OSMO_SS7_PC_INVALID.
Adjust all code paths using primary_pc to ensure it is indeed valid.

Rationale:

It looks like we are going to use the primary point-code of an SS7 instance to
derive a local SCCP address, e.g. for osmo-bsc and osmo-hnbgw.

 cs7-instance 1
  point-code 1.2.3   ! sets osmo_ss7_instance.primary_pc = 1.2.3
  sccp-address msc
   point-code 0.0.1
   routing-indicator PC

 hnb
  iucs
   remote-addr msc   ! derives cs7 instance 1 and local pc 1.2.3

If 'point-code 1.2.3' is omitted, this becomes '0.0.0' without the user
noticing, and this happens for each client that omits it. I would like to barf
when no local PC is set.

Change-Id: I7f0f0c89b7335d9da24161bfac8234be214ca00c

src/osmo_ss7.c

@@ -354,6 +354,8 @@ osmo_ss7_instance_find_or_create(void *ctx, uint32_t id)
 	if (!inst)
 		return NULL;
 
+	inst->cfg.primary_pc = OSMO_SS7_PC_INVALID;
+
 	inst->cfg.id = id;
 	LOGSS7(inst, LOGL_INFO, "Creating SS7 Instance\n");
 
@@ -1825,7 +1827,7 @@ void osmo_ss7_xua_server_destroy(struct osmo_xua_server *xs)
 bool osmo_ss7_pc_is_local(struct osmo_ss7_instance *inst, uint32_t pc)
 {
 	OSMO_ASSERT(ss7_initialized);
-	if (pc == inst->cfg.primary_pc)
+	if (osmo_ss7_pc_is_valid(inst->cfg.primary_pc) && pc == inst->cfg.primary_pc)
 		return true;
 	/* FIXME: Secondary and Capability Point Codes */
 	return false;

src/osmo_ss7_vty.c

@@ -166,7 +166,7 @@ DEFUN(cs7_point_code, cs7_point_code_cmd,
 {
 	struct osmo_ss7_instance *inst = vty->index;
 	int pc = osmo_ss7_pointcode_parse(inst, argv[0]);
-	if (pc < 0) {
+	if (pc < 0 || !osmo_ss7_pc_is_valid((uint32_t)pc)) {
 		vty_out(vty, "Invalid point code (%s)%s", argv[0], VTY_NEWLINE);
 		return CMD_WARNING;
 	}
@@ -1536,7 +1536,7 @@ static void write_one_cs7(struct vty *vty, struct osmo_ss7_instance *inst)
 	if (inst->cfg.pc_fmt.delimiter != '.')
 		vty_out(vty, " point-code delimiter dash%s", VTY_NEWLINE);
 
-	if (inst->cfg.primary_pc)
+	if (osmo_ss7_pc_is_valid(inst->cfg.primary_pc))
 		vty_out(vty, " point-code %s%s",
 			osmo_ss7_pointcode_print(inst, inst->cfg.primary_pc),
 			VTY_NEWLINE);

src/sccp_scoc.c

@@ -1670,11 +1670,11 @@ static void vty_show_connection(struct vty *vty, struct sccp_connection *conn)
 {
 	struct osmo_ss7_instance *s7i = conn->inst->ss7;
 	struct osmo_sccp_addr *remote_addr;
-	uint32_t local_pc;
+	uint32_t local_pc = OSMO_SS7_PC_INVALID;
 
 	if (conn->user->pc_valid)
 		local_pc = conn->user->pc;
-	else
+	else if (osmo_ss7_pc_is_valid(s7i->cfg.primary_pc))
 		local_pc = s7i->cfg.primary_pc;
 
 	if (conn->incoming)

src/sccp_scrc.c

@@ -91,8 +91,14 @@ static int sua2sccp_tx_m3ua(struct osmo_sccp_instance *inst,
 	param = &omp->u.transfer;
 	if (sua->mtp.opc)
 		param->opc = sua->mtp.opc;
-	else
+	else {
+		if (!osmo_ss7_pc_is_valid(s7i->cfg.primary_pc)) {
+			LOGP(DLSCCP, LOGL_ERROR, "SS7 instance %u: no primary point-code set\n",
+			     s7i->cfg.id);
+			return -1;
+		}
 		param->opc = s7i->cfg.primary_pc;
+	}
 	param->dpc = remote_pc;
 	param->sls = sua->mtp.sls;
 	param->sio = MTP_SIO(MTP_SI_SCCP, s7i->cfg.network_indicator);

src/sccp_user.c

@@ -366,6 +366,11 @@ osmo_sccp_simple_client_on_ss7_id(void *ctx, uint32_t ss7_id, const char *name,
 			goto out_ss7;
 		as_created = true;
 
+		if (!osmo_ss7_pc_is_valid(ss7->cfg.primary_pc)) {
+			LOGP(DLSCCP, LOGL_ERROR, "SS7 instance %u: no primary point-code set\n",
+			     ss7->cfg.id);
+			goto out_ss7;
+		}
 		as->cfg.routing_key.pc = ss7->cfg.primary_pc;
 
 		/* install default route */