[M] Change in osmo-smlc[master]: smlc: Initial implementation of N-PCSTATE.ind

15 Jul 2025

pespin has submitted this change. ( https://gerrit.osmocom.org/c/osmo-smlc/+/40665?usp=email )
(
4 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the submitted one.
 )Change subject: smlc: Initial implementation of N-PCSTATE.ind
......................................................................
smlc: Initial implementation of N-PCSTATE.ind
Related: OS#5917
Change-Id: Id034a0c4d8bff0647a64658480dfa9b4cea563de
---
M include/osmocom/smlc/lb_peer.h
M src/osmo-smlc/lb_peer.c
M src/osmo-smlc/sccp_lb_inst.c
3 files changed, 155 insertions(+), 2 deletions(-)
Approvals:
  laforge: Looks good to me, but someone else must approve
  fixeria: Looks good to me, approved
  Jenkins Builder: Verified

diff --git a/include/osmocom/smlc/lb_peer.h b/include/osmocom/smlc/lb_peer.h
index 5851a95..dc65b24 100644
--- a/include/osmocom/smlc/lb_peer.h
+++ b/include/osmocom/smlc/lb_peer.h
@@ -1,5 +1,7 @@
 #pragma once
+#include <stdint.h>
+
 #include <osmocom/core/linuxlist.h>
 #include <osmocom/gsm/gsm0808.h>
 #include <osmocom/sigtran/sccp_sap.h>
@@ -49,6 +51,8 @@
    LB_PEER_EV_MSG_DOWN_CO,
    LB_PEER_EV_RX_RESET,
    LB_PEER_EV_RX_RESET_ACK,
+	LB_PEER_EV_AVAILABLE,
+	LB_PEER_EV_UNAVAILABLE,
 };
struct lb_peer_ev_ctx {
@@ -59,6 +63,7 @@
struct lb_peer *lb_peer_find_or_create(struct sccp_lb_inst *sli, const struct osmo_sccp_addr *peer_addr);
 struct lb_peer *lb_peer_find(const struct sccp_lb_inst *sli, const struct osmo_sccp_addr *peer_addr);
+struct lb_peer *lb_peer_find_by_pc(const struct sccp_lb_inst *sli, uint32_t pc);
int lb_peer_up_l2(struct sccp_lb_inst *sli, const struct osmo_sccp_addr *calling_addr, bool co, uint32_t conn_id,
    	  struct msgb *l2);
diff --git a/src/osmo-smlc/lb_peer.c b/src/osmo-smlc/lb_peer.c
index 54e0ad2..fa2bc17 100644
--- a/src/osmo-smlc/lb_peer.c
+++ b/src/osmo-smlc/lb_peer.c
@@ -1,5 +1,5 @@
 /*
- * (C) 2019 by sysmocom - s.f.m.c. GmbH info@sysmocom.de
+ * (C) 2019-2025 by sysmocom - s.f.m.c. GmbH info@sysmocom.de
  * All Rights Reserved
  *
  * SPDX-License-Identifier: AGPL-3.0+
@@ -80,6 +80,15 @@
    return NULL;
 }
+/* Find an lb_peer by its remote SCCP address */
+struct lb_peer *lb_peer_find_by_pc(const struct sccp_lb_inst *sli, uint32_t pc)
+{
+	struct osmo_sccp_addr rem_addr;
+
+	osmo_sccp_make_addr_pc_ssn(&rem_addr, pc, OSMO_SCCP_SSN_BSC_BSSAP_LE);
+	return lb_peer_find(sli, &rem_addr);
+}
+
 static const struct osmo_tdef_state_timeout lb_peer_fsm_timeouts[32] = {
    [LB_PEER_ST_WAIT_RX_RESET_ACK] = { .T = -13 },
    [LB_PEER_ST_DISCARDING] = { .T = -14 },
@@ -235,6 +244,15 @@
    	lb_peer_rx_reset(lbp, msg);
    	return;
+	case LB_PEER_EV_AVAILABLE:
+		/* Send a RESET to the peer. */
+		lb_peer_reset(lbp);
+		return;
+
+	case LB_PEER_EV_UNAVAILABLE:
+		/* Do nothing, wait for peer to come up again. */
+		return;
+
    default:
    	LOG_LB_PEER(lbp, LOGL_ERROR, "Unhandled event: %s\n", osmo_fsm_event_name(&lb_peer_fsm, event));
    	return;
@@ -270,6 +288,15 @@
    	lb_peer_rx_reset(lbp, msg);
    	return;
+	case LB_PEER_EV_AVAILABLE:
+		/* Send a RESET to the peer. */
+		lb_peer_reset(lbp);
+		return;
+
+	case LB_PEER_EV_UNAVAILABLE:
+		lb_peer_state_chg(lbp, LB_PEER_ST_WAIT_RX_RESET);
+		return;
+
    default:
    	LOG_LB_PEER(lbp, LOGL_ERROR, "Unhandled event: %s\n", osmo_fsm_event_name(&lb_peer_fsm, event));
    	return;
@@ -334,6 +361,16 @@
    	lb_peer_rx_reset(lbp, msg);
    	return;
+	case LB_PEER_EV_AVAILABLE:
+		/* Send a RESET to the peer. */
+		lb_peer_reset(lbp);
+		return;
+
+	case LB_PEER_EV_UNAVAILABLE:
+		lb_peer_discard_all_conns(lbp);
+		lb_peer_state_chg(lbp, LB_PEER_ST_WAIT_RX_RESET);
+		return;
+
    default:
    	LOG_LB_PEER(lbp, LOGL_ERROR, "Unhandled event: %s\n", osmo_fsm_event_name(&lb_peer_fsm, event));
    	return;
@@ -363,6 +400,8 @@
    OSMO_VALUE_STRING(LB_PEER_EV_MSG_DOWN_CO),
    OSMO_VALUE_STRING(LB_PEER_EV_RX_RESET),
    OSMO_VALUE_STRING(LB_PEER_EV_RX_RESET_ACK),
+	OSMO_VALUE_STRING(LB_PEER_EV_AVAILABLE),
+	OSMO_VALUE_STRING(LB_PEER_EV_UNAVAILABLE),
    {}
 };
@@ -376,6 +415,8 @@
    		| S(LB_PEER_EV_RX_RESET)
    		| S(LB_PEER_EV_MSG_UP_CO_INITIAL)
    		| S(LB_PEER_EV_MSG_UP_CO)
+			| S(LB_PEER_EV_AVAILABLE)
+			| S(LB_PEER_EV_UNAVAILABLE)
    		,
    	.out_state_mask = 0
    		| S(LB_PEER_ST_WAIT_RX_RESET)
@@ -392,6 +433,8 @@
    		| S(LB_PEER_EV_RX_RESET_ACK)
    		| S(LB_PEER_EV_MSG_UP_CO_INITIAL)
    		| S(LB_PEER_EV_MSG_UP_CO)
+			| S(LB_PEER_EV_AVAILABLE)
+			| S(LB_PEER_EV_UNAVAILABLE)
    		,
    	.out_state_mask = 0
    		| S(LB_PEER_ST_WAIT_RX_RESET)
@@ -410,6 +453,8 @@
    		| S(LB_PEER_EV_MSG_DOWN_CO_INITIAL)
    		| S(LB_PEER_EV_MSG_DOWN_CO)
    		| S(LB_PEER_EV_MSG_DOWN_CL)
+			| S(LB_PEER_EV_AVAILABLE)
+			| S(LB_PEER_EV_UNAVAILABLE)
    		,
    	.out_state_mask = 0
    		| S(LB_PEER_ST_WAIT_RX_RESET)
diff --git a/src/osmo-smlc/sccp_lb_inst.c b/src/osmo-smlc/sccp_lb_inst.c
index e10effe..bfe8a0e 100644
--- a/src/osmo-smlc/sccp_lb_inst.c
+++ b/src/osmo-smlc/sccp_lb_inst.c
@@ -1,5 +1,5 @@
 /*
- * (C) 2020 by sysmocom - s.f.m.c. GmbH info@sysmocom.de
+ * (C) 2020-2025 by sysmocom - s.f.m.c. GmbH info@sysmocom.de
  * All Rights Reserved
  *
  * SPDX-License-Identifier: AGPL-3.0+
@@ -85,6 +85,96 @@
    return sli;
 }
+static void handle_pcstate_ind(struct sccp_lb_inst *sli, const struct osmo_scu_pcstate_param *pcst)
+{
+	struct osmo_ss7_instance *cs7 = osmo_sccp_get_ss7(sli->sccp);
+	struct lb_peer *lbp;
+	bool connected;
+	bool disconnected;
+
+	LOG_SCCP_LB(sli, LOGL_DEBUG, "N-PCSTATE ind: affected_pc=%u=%s sp_status=%s remote_sccp_status=%s\n",
+		    pcst->affected_pc, osmo_ss7_pointcode_print(cs7, pcst->affected_pc),
+		    osmo_sccp_sp_status_name(pcst->sp_status),
+		    osmo_sccp_rem_sccp_status_name(pcst->remote_sccp_status));
+
+	/* If we don't care about that point-code, ignore PCSTATE. */
+	lbp = lb_peer_find_by_pc(sli, pcst->affected_pc);
+	if (!lbp) {
+		LOG_SCCP_LB(sli, LOGL_DEBUG, "No lb_peer found under pc=%u=%s\n",
+			    pcst->affected_pc, osmo_ss7_pointcode_print(cs7, pcst->affected_pc));
+		return;
+	}
+
+	/* See if this marks the point code to have become available, or to have been lost.
+	 *
+	 * I want to detect two events:
+	 * - connection event (both indicators say PC is reachable).
+	 * - disconnection event (at least one indicator says the PC is not reachable).
+	 *
+	 * There are two separate incoming indicators with various possible values -- the incoming events can be:
+	 *
+	 * - neither connection nor disconnection indicated -- just indicating congestion
+	 *   connected == false, disconnected == false --> do nothing.
+	 * - both incoming values indicate that we are connected
+	 *   --> trigger connected
+	 * - both indicate we are disconnected
+	 *   --> trigger disconnected
+	 * - one value indicates 'connected', the other indicates 'disconnected'
+	 *   --> trigger disconnected
+	 *
+	 * Congestion could imply that we're connected, but it does not indicate that a PC's reachability changed, so no need to
+	 * trigger on that.
+	 */
+	connected = false;
+	disconnected = false;
+
+	switch (pcst->sp_status) {
+	case OSMO_SCCP_SP_S_ACCESSIBLE:
+		connected = true;
+		break;
+	case OSMO_SCCP_SP_S_INACCESSIBLE:
+		disconnected = true;
+		break;
+	default:
+	case OSMO_SCCP_SP_S_CONGESTED:
+		/* Neither connecting nor disconnecting */
+		break;
+	}
+
+	switch (pcst->remote_sccp_status) {
+	case OSMO_SCCP_REM_SCCP_S_AVAILABLE:
+		if (!disconnected)
+			connected = true;
+		break;
+	case OSMO_SCCP_REM_SCCP_S_UNAVAILABLE_UNKNOWN:
+	case OSMO_SCCP_REM_SCCP_S_UNEQUIPPED:
+	case OSMO_SCCP_REM_SCCP_S_INACCESSIBLE:
+		disconnected = true;
+		connected = false;
+		break;
+	default:
+	case OSMO_SCCP_REM_SCCP_S_CONGESTED:
+		/* Neither connecting nor disconnecting */
+		break;
+	}
+
+	if (disconnected) {
+		LOG_SCCP_LB(sli, LOGL_NOTICE,
+			    "now unreachable: N-PCSTATE ind: pc=%u=%s sp_status=%s remote_sccp_status=%s\n",
+			    pcst->affected_pc, osmo_ss7_pointcode_print(cs7, pcst->affected_pc),
+			    osmo_sccp_sp_status_name(pcst->sp_status),
+			    osmo_sccp_rem_sccp_status_name(pcst->remote_sccp_status));
+		osmo_fsm_inst_dispatch(lbp->fi, LB_PEER_EV_UNAVAILABLE, NULL);
+	} else if (connected) {
+		LOG_SCCP_LB(sli, LOGL_NOTICE,
+			    "now available: N-PCSTATE ind: pc=%u=%s sp_status=%s remote_sccp_status=%s\n",
+			    pcst->affected_pc, osmo_ss7_pointcode_print(cs7, pcst->affected_pc),
+			    osmo_sccp_sp_status_name(pcst->sp_status),
+			    osmo_sccp_rem_sccp_status_name(pcst->remote_sccp_status));
+		osmo_fsm_inst_dispatch(lbp->fi, LB_PEER_EV_AVAILABLE, NULL);
+	}
+}
+
 static int sccp_lb_sap_up(struct osmo_prim_hdr *oph, void *_scu)
 {
    struct osmo_sccp_user *scu = _scu;
@@ -163,6 +253,19 @@
    	rc = lb_peer_up_l2(sli, peer_addr, false, 0, oph->msg);
    	break;
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_PCSTATE, PRIM_OP_INDICATION):
+		handle_pcstate_ind(sli, &prim->u.pcstate);
+		rc = 0;
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_STATE, PRIM_OP_INDICATION):
+		LOG_SCCP_LB(sli, LOGL_INFO,
+			    "SCCP-User-SAP: Ignoring %s.%s\n",
+			    osmo_scu_prim_type_name(oph->primitive),
+			    get_value_string(osmo_prim_op_names, oph->operation));
+		rc = 0;
+		break;
+
    default:
    	LOG_SCCP_LB_CL(sli, NULL, LOGL_ERROR, "%s(%s) unsupported\n", __func__, osmo_scu_prim_name(oph));
    	rc = -1;
-- 
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Gerrit-MessageType: merged
Gerrit-Project: osmo-smlc
Gerrit-Branch: master
Gerrit-Change-Id: Id034a0c4d8bff0647a64658480dfa9b4cea563de
Gerrit-Change-Number: 40665
Gerrit-PatchSet: 5
Gerrit-Owner: pespin pespin@sysmocom.de
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria vyanitskiy@sysmocom.de
Gerrit-Reviewer: laforge laforge@osmocom.org
Gerrit-Reviewer: pespin pespin@sysmocom.de



    

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[M] Change in osmo-smlc[master]: smlc: Initial implementation of N-PCSTATE.ind