M3UA/SUA: Implement handling of SCON (signaling congestion)

If we receive any M3UA/SUA SNM SCON mesasages, distribute them
to any other active ASP to make everyone aware of the congestion
situation.

This makes STP_Tests_M3UA.TC_ssnm_distribution_scon pass and hence
should turn the entire osmo-stp test suite "green"

Change-Id: Iac7aeba980fbbd8b58f8872a29ba10745eb0a730

4 files changed, 139 insertions, 0 deletions

diff --git a/src/m3ua.c b/src/m3ua.c
index 741063c..63297fe 100644
--- a/src/m3ua.c
+++ b/src/m3ua.c
@@ -864,6 +864,40 @@ void m3ua_tx_snm_available(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsig
 	xua_msg_free(xua);
 }
 
+/*! Transmit SSNM SCON message indicating congestion
+ *  \param[in] asp ASP through which to transmit message. Must be ACTIVE.
+ *  \param[in] rctx array of Routing Contexts in network byte order.
+ *  \param[in] num_rctx number of rctx
+ *  \param[in] aff_pc array of 'Affected Point Code' in network byte order.
+ *  \param[in] num_aff_pc number of aff_pc
+ *  \param[in] concerned_dpc optional concerned DPC (can be NULL)
+ *  \param[in] cong_level optional congestion level (can be NULL)
+ *  \param[in] info_string optional information string (can be NULL). */
+void m3ua_tx_snm_congestion(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
+			    const uint32_t *aff_pc, unsigned int num_aff_pc,
+			    const uint32_t *concerned_dpc, const uint8_t *cong_level,
+			    const char *info_string)
+{
+	struct xua_msg *xua = xua_msg_alloc();
+
+	xua->hdr = XUA_HDR(M3UA_MSGC_SNM, M3UA_SNM_SCON);
+	xua->hdr.version = M3UA_VERSION;
+	if (rctx)
+		xua_msg_add_data(xua, M3UA_IEI_ROUTE_CTX, num_rctx * sizeof(*rctx), (const uint8_t *)rctx);
+
+	xua_msg_add_data(xua, M3UA_IEI_AFFECTED_PC, num_aff_pc * sizeof(*aff_pc), (const uint8_t *) aff_pc);
+
+	if (concerned_dpc)
+		xua_msg_add_u32(xua, M3UA_IEI_CONC_DEST, *concerned_dpc & 0xffffff);
+	if (cong_level)
+		xua_msg_add_u32(xua, M3UA_IEI_CONG_IND, *cong_level & 0xff);
+	if (info_string)
+		xua_msg_add_data(xua, M3UA_IEI_INFO_STRING, strlen(info_string)+1, (const uint8_t *) info_string);
+
+	m3ua_tx_xua_asp(asp, xua);
+	xua_msg_free(xua);
+}
+
 /*! Transmit SSNM DUPU message indicating user unavailability.
  *  \param[in] asp ASP through which to transmit message. Must be ACTIVE.
  *  \param[in] rctx array of Routing Contexts in network byte order.
@@ -903,6 +937,8 @@ static int m3ua_rx_snm_asp(struct osmo_ss7_asp *asp, struct xua_msg *xua)
 		xua_snm_rx_dupu(asp, as, xua);
 		break;
 	case M3UA_SNM_SCON:
+		xua_snm_rx_scon(asp, as, xua);
+		break;
 	case M3UA_SNM_DRST:
 		LOGPASP(asp, DLM3UA, LOGL_NOTICE, "Received unsupported M3UA SNM message type %u\n",
 			xua->hdr.msg_type);
diff --git a/src/sua.c b/src/sua.c
index 000f064..bd51005 100644
--- a/src/sua.c
+++ b/src/sua.c
@@ -875,6 +875,35 @@ void sua_tx_snm_available(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsign
 	sua_tx_xua_asp(asp, xua);
 }
 
+
+/*! Transmit SSNM SCON message indicating congestion
+ *  \param[in] asp ASP through which to transmit message. Must be ACTIVE.
+ *  \param[in] rctx array of Routing Contexts in network byte order.
+ *  \param[in] num_rctx number of rctx
+ *  \param[in] aff_pc array of 'Affected Point Code' in network byte order.
+ *  \param[in] num_aff_pc number of aff_pc
+ *  \param[in] ssn optional SSN (can be NULL)
+ *  \param[in] cong_level optional congestion level (can be NULL)
+ *  \param[in] info_string optional information string (can be NULL). */
+void sua_tx_snm_congestion(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
+			   const uint32_t *aff_pc, unsigned int num_aff_pc, const uint32_t *ssn,
+			   const uint8_t cong_level, const char *info_string)
+{
+	struct xua_msg *xua = xua_msg_alloc();
+
+	xua->hdr = XUA_HDR(SUA_MSGC_SNM, SUA_SNM_SCON);
+	xua->hdr.version = SUA_VERSION;
+	if (rctx)
+		xua_msg_add_data(xua, SUA_IEI_ROUTE_CTX, num_rctx * sizeof(*rctx), (const uint8_t *)rctx);
+	xua_msg_add_data(xua, SUA_IEI_AFFECTED_PC, num_aff_pc * sizeof(*aff_pc), (const uint8_t *) aff_pc);
+	if (ssn)
+		xua_msg_add_u32(xua, SUA_IEI_SSN, *ssn);
+	xua_msg_add_u32(xua, SUA_IEI_CONG_LEVEL, cong_level);
+	if (info_string)
+		xua_msg_add_data(xua, SUA_IEI_INFO_STRING, strlen(info_string)+1, (const uint8_t *) info_string);
+}
+
+
 /*! Transmit SSNM DUPU message indicating user unavailability.
  *  \param[in] asp ASP through which to transmit message. Must be ACTIVE.
  *  \param[in] rctx array of Routing Contexts in network byte order.
diff --git a/src/xua_internal.h b/src/xua_internal.h
index 4c6bb29..5dd7066 100644
--- a/src/xua_internal.h
+++ b/src/xua_internal.h
@@ -21,6 +21,9 @@ int sua_tx_xua_as(struct osmo_ss7_as *as, struct xua_msg *xua);
 void sua_tx_snm_available(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
 			  const uint32_t *aff_pc, unsigned int num_aff_pc, const uint32_t *aff_ssn,
 			  const uint32_t *smi, const char *info_string, bool available);
+void sua_tx_snm_congestion(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
+			   const uint32_t *aff_pc, unsigned int num_aff_pc, const uint32_t *ssn,
+			   const uint8_t cong_level, const char *info_string);
 void sua_tx_dupu(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
 		 uint32_t dpc, uint16_t user, uint16_t cause, const char *info_str);
 
@@ -30,12 +33,18 @@ int m3ua_tx_xua_as(struct osmo_ss7_as *as, struct xua_msg *xua);
 void m3ua_tx_snm_available(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
 			   const uint32_t *aff_pc, unsigned int num_aff_pc,
 			   const char *info_string, bool available);
+void m3ua_tx_snm_congestion(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
+			    const uint32_t *aff_pc, unsigned int num_aff_pc,
+			    const uint32_t *concerned_dpc, const uint8_t *cong_level,
+			    const char *info_string);
 void m3ua_tx_dupu(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
 		  uint32_t dpc, uint16_t user, uint16_t cause, const char *info_str);
+
 void xua_snm_rx_daud(struct osmo_ss7_asp *asp, struct xua_msg *xua);
 void xua_snm_rx_duna(struct osmo_ss7_asp *asp, struct osmo_ss7_as *as, struct xua_msg *xua);
 void xua_snm_rx_dava(struct osmo_ss7_asp *asp, struct osmo_ss7_as *as, struct xua_msg *xua);
 void xua_snm_rx_dupu(struct osmo_ss7_asp *asp, struct osmo_ss7_as *as, struct xua_msg *xua);
+void xua_snm_rx_scon(struct osmo_ss7_asp *asp, struct osmo_ss7_as *as, struct xua_msg *xua);
 int m3ua_rx_msg(struct osmo_ss7_asp *asp, struct msgb *msg);
 
 struct msgb *m3ua_msgb_alloc(const char *name);
diff --git a/src/xua_snm.c b/src/xua_snm.c
index 0c14964..1212162 100644
--- a/src/xua_snm.c
+++ b/src/xua_snm.c
@@ -115,6 +115,24 @@ static void xua_tx_upu(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned
 	}
 }
 
+static void xua_tx_scon(struct osmo_ss7_asp *asp, const uint32_t *rctx, unsigned int num_rctx,
+			const uint32_t *aff_pc, unsigned int num_aff_pc,
+			const uint32_t *concerned_dpc, const uint8_t *cong_level,
+			const char *info_string)
+{
+	switch (asp->cfg.proto) {
+	case OSMO_SS7_ASP_PROT_M3UA:
+		m3ua_tx_snm_congestion(asp, rctx, num_rctx, aff_pc, num_aff_pc,
+				       concerned_dpc, cong_level, info_string);
+		break;
+	case OSMO_SS7_ASP_PROT_SUA:
+		sua_tx_snm_congestion(asp, rctx, num_rctx, aff_pc, num_aff_pc, NULL,
+				      cong_level ? *cong_level : 0, info_string);
+		break;
+	default:
+		break;
+	}
+}
 
 /* generate MTP-PAUSE / MTP-RESUME towards local SCCP users */
 static void xua_snm_pc_available_to_sccp(struct osmo_sccp_instance *sccp,
@@ -257,6 +275,36 @@ static void xua_snm_upu(struct osmo_ss7_as *as, uint32_t dpc, uint16_t user, uin
 	}
 }
 
+static void xua_snm_scon(struct osmo_ss7_as *as, const uint32_t *aff_pc, unsigned int num_aff_pc,
+			 const uint32_t *concerned_dpc, const uint8_t *cong_level, const char *info_string)
+{
+	struct osmo_ss7_instance *s7i = as->inst;
+	struct osmo_ss7_asp *asp;
+	uint32_t rctx[32];
+	unsigned int num_rctx;
+
+	/* TODO: How to translate to MTP and towards SCCP (create N-PCSTATE.ind to SCU) */
+
+	/* inform remote ASPs via SCON */
+	llist_for_each_entry(asp, &s7i->asp_list, list) {
+		/* SSNM is only permitted for ASPs in ACTIVE state */
+		if (!osmo_ss7_asp_active(asp))
+			continue;
+
+		/* only send SCON if we locally are the SG and the remote is ASP */
+		if (asp->cfg.role != OSMO_SS7_ASP_ROLE_SG)
+			continue;
+
+		num_rctx = get_all_rctx_for_asp(rctx, ARRAY_SIZE(rctx), asp, as);
+		/* this can happen if the given ASP is only in the AS that reports the change,
+		 * which shall be excluded */
+		if (num_rctx == 0)
+			continue;
+
+		xua_tx_scon(asp, rctx, num_rctx, aff_pc, num_aff_pc, concerned_dpc, cong_level, info_string);
+	}
+}
+
 /* receive DAUD from ASP; pc is 'affected PC' IE with mask in network byte order! */
 void xua_snm_rx_daud(struct osmo_ss7_asp *asp, struct xua_msg *xua)
 {
@@ -405,3 +453,20 @@ void xua_snm_rx_dupu(struct osmo_ss7_asp *asp, struct osmo_ss7_as *as, struct xu
 
 	xua_snm_upu(as, aff_pc, user, cause, info_str);
 }
+
+/* an incoming SUA/M3UA SCON was received from a remote SG */
+void xua_snm_rx_scon(struct osmo_ss7_asp *asp, struct osmo_ss7_as *as, struct xua_msg *xua)
+{
+	struct xua_msg_part *ie_aff_pc = xua_msg_find_tag(xua, M3UA_IEI_AFFECTED_PC);
+	const char *info_str = xua_msg_get_str(xua, M3UA_IEI_INFO_STRING);
+	uint32_t _concerned_dpc, _cong_level;
+	const uint32_t *concerned_dpc = xua_msg_get_u32p(xua, M3UA_IEI_CONC_DEST, &_concerned_dpc);
+	const uint32_t *cong_level = xua_msg_get_u32p(xua, M3UA_IEI_CONG_IND, &_cong_level);
+	int log_ss = osmo_ss7_asp_get_log_subsys(asp);
+
+	LOGPASP(asp, log_ss, LOGL_NOTICE, "RX SCON(%s) for %s level=%u\n", info_str ? info_str : "",
+		format_affected_pcs_c(xua, asp->inst, ie_aff_pc), cong_level ? *cong_level : 0);
+
+	xua_snm_scon(as, (const uint32_t *) ie_aff_pc->dat, ie_aff_pc->len / sizeof(uint32_t),
+		     concerned_dpc, (const uint8_t *) cong_level, info_str);
+}