From 68b4f037e0e2286fd2fe1f314d9bd2dc66fb646b Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@gnumonks.org>
Date: Wed, 9 Jun 2010 16:22:28 +0200
Subject: [GPRS] BSSGP/SGSN: Implement Gb-Interface Paging

We now have a function that generates BSSGP PS and CS paging request.

It is called from the libgtp code when we receive a GTP packet from
the GGSN for a MM context that is in SUSPEND state.  We then issue
a PS paging request to the Cell with the BVCI where the last RA update
was being performed.

TODO: We still don't enqueue the GTP packet (and transmit it on paging
complete), and we don't rate-limit the paging requests, i.e. every GTP packet
will trigger another paging request.

We probably also need some kind of logic that marks the phone as UNREGISTERED
if it doesn't respond to paging requests for some time.
---
 openbsc/src/gprs/gprs_bssgp.c | 63 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

(limited to 'openbsc/src')

diff --git a/openbsc/src/gprs/gprs_bssgp.c b/openbsc/src/gprs/gprs_bssgp.c
index c7c49d4b..f27e3a7e 100644
--- a/openbsc/src/gprs/gprs_bssgp.c
+++ b/openbsc/src/gprs/gprs_bssgp.c
@@ -787,3 +787,66 @@ int gprs_bssgp_tx_dl_ud(struct msgb *msg, struct sgsn_mm_ctx *mmctx)
 
 	return gprs_ns_sendmsg(bssgp_nsi, msg);
 }
+
+/* Send a single GMM-PAGING.req to a given NSEI/NS-BVCI */
+int gprs_bssgp_tx_paging(uint16_t nsei, uint16_t ns_bvci,
+			 struct bssgp_paging_info *pinfo)
+{
+	struct msgb *msg = bssgp_msgb_alloc();
+	struct bssgp_normal_hdr *bgph =
+			(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
+	uint16_t drx_params = htons(pinfo->drx_params);
+	uint8_t mi[10];
+	int imsi_len = gsm48_generate_mid_from_imsi(mi, pinfo->imsi);
+	uint8_t ra[6];
+
+	if (imsi_len < 2)
+		return -EINVAL;
+
+	msgb_nsei(msg) = nsei;
+	msgb_bvci(msg) = ns_bvci;
+
+	if (pinfo->mode == BSSGP_PAGING_PS)
+		bgph->pdu_type = BSSGP_PDUT_PAGING_PS;
+	else
+		bgph->pdu_type = BSSGP_PDUT_PAGING_CS;
+	/* IMSI */
+	msgb_tvlv_put(msg, BSSGP_IE_IMSI, imsi_len-2, mi+2);
+	/* DRX Parameters */
+	msgb_tvlv_put(msg, BSSGP_IE_DRX_PARAMS, 2,
+			(uint8_t *) &drx_params);
+	/* Scope */
+	switch (pinfo->scope) {
+	case BSSGP_PAGING_BSS_AREA:
+		{
+			uint8_t null = 0;
+			msgb_tvlv_put(msg, BSSGP_IE_BSS_AREA_ID, 1, &null);
+		}
+		break;
+	case BSSGP_PAGING_LOCATION_AREA:
+		gsm48_construct_ra(ra, &pinfo->raid);
+		msgb_tvlv_put(msg, BSSGP_IE_LOCATION_AREA, 4, ra);
+		break;
+	case BSSGP_PAGING_ROUTEING_AREA:
+		gsm48_construct_ra(ra, &pinfo->raid);
+		msgb_tvlv_put(msg, BSSGP_IE_ROUTEING_AREA, 6, ra);
+		break;
+	case BSSGP_PAGING_BVCI:
+		{
+			uint16_t bvci = htons(pinfo->bvci);
+			msgb_tvlv_put(msg, BSSGP_IE_BVCI, 2, (uint8_t *)&bvci);
+		}
+		break;
+	}
+	/* QoS profile mandatory for PS */
+	if (pinfo->mode == BSSGP_PAGING_PS)
+		msgb_tvlv_put(msg, BSSGP_IE_QOS_PROFILE, 3, pinfo->qos);
+
+	/* Optional (P-)TMSI */
+	if (pinfo->ptmsi) {
+		uint32_t ptmsi = htonl(*pinfo->ptmsi);
+		msgb_tvlv_put(msg, BSSGP_IE_TMSI, 4, (uint8_t *) &ptmsi);
+	}
+
+	return gprs_ns_sendmsg(bssgp_nsi, msg);
+}
-- 
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