pespin has uploaded this change for review. ( 
https://gerrit.osmocom.org/c/osmo-msc/+/40630?usp=email )


Change subject: msc: Initial implementation of N-PCSTATE.ind
......................................................................

msc: Initial implementation of N-PCSTATE.ind

Change-Id: Ice1b2c163b1b0d134fcaa1c8bf543038a35fabdf
---
M include/osmocom/msc/ran_peer.h
M src/libmsc/ran_peer.c
M src/libmsc/sccp_ran.c
3 files changed, 127 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-msc refs/changes/30/40630/1

diff --git a/include/osmocom/msc/ran_peer.h b/include/osmocom/msc/ran_peer.h
index c936d5c..211dd44 100644
--- a/include/osmocom/msc/ran_peer.h
+++ b/include/osmocom/msc/ran_peer.h
@@ -91,7 +91,7 @@
 };

 struct ran_peer *ran_peer_find_or_create(struct sccp_ran_inst *sri, const 
struct osmo_sccp_addr *peer_addr);
-struct ran_peer *ran_peer_find_by_addr(struct sccp_ran_inst *sri, const struct 
osmo_sccp_addr *peer_addr);
+struct ran_peer *ran_peer_find_by_addr(const struct sccp_ran_inst *sri, const 
struct osmo_sccp_addr *peer_addr);

 void ran_peer_cells_seen_add(struct ran_peer *ran_peer, const struct 
gsm0808_cell_id *id);

@@ -104,5 +104,8 @@
 int ran_peer_down_paging(struct ran_peer *rp, const struct gsm0808_cell_id 
*page_id, struct vlr_subscr *vsub,
                         enum paging_cause cause);

+void ran_peer_reset(struct ran_peer *rp);
+void ran_peer_becomes_unreachable(struct ran_peer *rp);
+
 struct ran_peer *ran_peer_find_by_cell_id(struct sccp_ran_inst *sri, const 
struct gsm0808_cell_id *cid,
                                          bool expecting_single_match);
diff --git a/src/libmsc/ran_peer.c b/src/libmsc/ran_peer.c
index 09e57eb..bef753a 100644
--- a/src/libmsc/ran_peer.c
+++ b/src/libmsc/ran_peer.c
@@ -87,7 +87,7 @@
        return ran_peer_alloc(sri, peer_addr);
 }

-struct ran_peer *ran_peer_find_by_addr(struct sccp_ran_inst *sri, const struct 
osmo_sccp_addr *peer_addr)
+struct ran_peer *ran_peer_find_by_addr(const struct sccp_ran_inst *sri, const 
struct osmo_sccp_addr *peer_addr)
 {
        struct ran_peer *rp;
        llist_for_each_entry(rp, &sri->ran_peers, entry) {
@@ -128,6 +128,13 @@
        }
 }

+/* N-PCSTATE.ind informs us the peer went down and is no longer reachable: */
+void ran_peer_becomes_unreachable(struct ran_peer *rp)
+{
+       ran_peer_discard_all_conns(rp);
+       ran_peer_state_chg(rp, RAN_PEER_ST_WAIT_RX_RESET);
+}
+
 static void ran_peer_update_osmux_support(struct ran_peer *rp, int 
supports_osmux)
 {
        bool old_value = rp->remote_supports_osmux;
diff --git a/src/libmsc/sccp_ran.c b/src/libmsc/sccp_ran.c
index 9907f20..3a1bfd5 100644
--- a/src/libmsc/sccp_ran.c
+++ b/src/libmsc/sccp_ran.c
@@ -29,6 +29,7 @@
 #include <osmocom/msc/debug.h>
 #include <osmocom/msc/sccp_ran.h>
 #include <osmocom/msc/ran_infra.h>
+#include <osmocom/msc/ran_peer.h>

 struct osmo_tdef g_sccp_tdefs[] = {
        {}
@@ -59,6 +60,107 @@
        return sri;
 }

+/* Find an ran_peer (BSC/RNC) by its remote SCCP address */
+static struct ran_peer *get_ran_peer_by_pc(const struct sccp_ran_inst *sri, 
uint32_t pc)
+{
+       struct ran_peer *rp;
+       struct osmo_ss7_instance *cs7 = osmo_sccp_get_ss7(sri->sccp);
+       struct osmo_sccp_addr rem_addr;
+
+       osmo_sccp_make_addr_pc_ssn(&rem_addr, pc, sri->ran->ssn);
+       rp = ran_peer_find_by_addr(sri, &rem_addr);
+       if (rp)
+               return rp;
+       LOGP(DMSC, LOGL_DEBUG, "Nofind ran_peer found under remote address: 
%s\n", osmo_sccp_addr_name(cs7, &rem_addr));
+       return NULL;
+}
+
+static void handle_pcstate_ind(struct sccp_ran_inst *sri, const struct 
osmo_scu_pcstate_param *pcst)
+{
+       struct ran_peer *rp;
+       bool connected;
+       bool disconnected;
+
+       LOGP(DMSC, LOGL_DEBUG, "N-PCSTATE ind: affected_pc=%u sp_status=%s 
remote_sccp_status=%s\n",
+            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. */
+       rp = get_ran_peer_by_pc(sri, pcst->affected_pc);
+       if (!rp)
+               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 && rp->fi && rp->fi->state == RAN_PEER_ST_READY) {
+               LOG_RAN_PEER(rp, LOGL_NOTICE,
+                            "now unreachable: N-PCSTATE ind: pc=%u 
sp_status=%s remote_sccp_status=%s\n",
+                            pcst->affected_pc,
+                            osmo_sccp_sp_status_name(pcst->sp_status),
+                            
osmo_sccp_rem_sccp_status_name(pcst->remote_sccp_status));
+               ran_peer_becomes_unreachable(rp);
+               /* TODO: need to change state?! */
+       } else if (connected && rp->fi && rp->fi->state != RAN_PEER_ST_READY) {
+               LOG_RAN_PEER(rp, LOGL_NOTICE,
+                            "now available: N-PCSTATE ind: pc=%u sp_status=%s 
remote_sccp_status=%s\n",
+                            pcst->affected_pc,
+                            osmo_sccp_sp_status_name(pcst->sp_status),
+                            
osmo_sccp_rem_sccp_status_name(pcst->remote_sccp_status));
+               ran_peer_reset(rp);
+       }
+}
+
 static int sccp_ran_sap_up(struct osmo_prim_hdr *oph, void *_scu)
 {
        struct osmo_sccp_user *scu = _scu;
@@ -141,6 +243,19 @@
                rc = sri->ran->sccp_ran_ops.up_l2(sri, peer_addr, false, 0, 
oph->msg);
                break;

+       case OSMO_PRIM(OSMO_SCU_PRIM_N_PCSTATE, PRIM_OP_INDICATION):
+               handle_pcstate_ind(sri, &prim->u.pcstate);
+               rc = 0;
+               break;
+
+       case OSMO_PRIM(OSMO_SCU_PRIM_N_STATE, PRIM_OP_INDICATION):
+               LOG_SCCP_RAN_CL(sri, NULL, 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_RAN_CL(sri, NULL, LOGL_DEBUG, "%s(%s)\n", __func__, 
osmo_scu_prim_name(oph));
                rc = -1;

--
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Gerrit-MessageType: newchange
Gerrit-Project: osmo-msc
Gerrit-Branch: master
Gerrit-Change-Id: Ice1b2c163b1b0d134fcaa1c8bf543038a35fabdf
Gerrit-Change-Number: 40630
Gerrit-PatchSet: 1
Gerrit-Owner: pespin <[email protected]>

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