Create new 'gprs-sgsn' branch on top of 'gprs-conf'
This branch contains the partial SGSN/GGSN implementation that
was originally developed as part of the gprs branch.
diff --git a/openbsc/src/gprs_ns.c b/openbsc/src/gprs_ns.c
new file mode 100644
index 0000000..a686a22
--- /dev/null
+++ b/openbsc/src/gprs_ns.c
@@ -0,0 +1,348 @@
+/* GPRS Networks Service (NS) messages on the Gb interface
+ * 3GPP TS 08.16 version 8.0.1 Release 1999 / ETSI TS 101 299 V8.0.1 (2002-05) */
+
+/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+/* Some introduction into NS: NS is used typically on top of frame relay,
+ * but in the ip.access world it is encapsulated in UDP packets. It serves
+ * as an intermediate shim betwen BSSGP and the underlying medium. It doesn't
+ * do much, apart from providing congestion notification and status indication.
+ *
+ * Terms:
+ * NS Network Service
+ * NSVC NS Virtual Connection
+ * NSEI NS Entity Identifier
+ * NSVL NS Virtual Link
+ * NSVLI NS Virtual Link Identifier
+ * BVC BSSGP Virtual Connection
+ * BVCI BSSGP Virtual Connection Identifier
+ * NSVCG NS Virtual Connection Goup
+ * Blocked NS-VC cannot be used for user traffic
+ * Alive Ability of a NS-VC to provide communication
+ *
+ * There can be multiple BSSGP virtual connections over one (group of) NSVC's. BSSGP will
+ * therefore identify the BSSGP virtual connection by a BVCI passed down to NS.
+ * NS then has to firgure out which NSVC's are responsible for this BVCI.
+ * Those mappings are administratively configured.
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+
+#include <arpa/inet.h>
+
+#include <openbsc/gsm_data.h>
+#include <osmocore/msgb.h>
+#include <osmocore/tlv.h>
+#include <osmocore/talloc.h>
+#include <openbsc/debug.h>
+#include <openbsc/gprs_ns.h>
+#include <openbsc/gprs_bssgp.h>
+
+#define NS_ALLOC_SIZE 1024
+
+static const struct tlv_definition ns_att_tlvdef = {
+ .def = {
+ [NS_IE_CAUSE] = { TLV_TYPE_TvLV, 0 },
+ [NS_IE_VCI] = { TLV_TYPE_TvLV, 0 },
+ [NS_IE_PDU] = { TLV_TYPE_TvLV, 0 },
+ [NS_IE_BVCI] = { TLV_TYPE_TvLV, 0 },
+ [NS_IE_NSEI] = { TLV_TYPE_TvLV, 0 },
+ },
+};
+
+#define NSE_S_BLOCKED 0x0001
+#define NSE_S_ALIVE 0x0002
+
+struct gprs_nsvc {
+ struct llist_head list;
+
+ u_int16_t nsei; /* end-to-end significance */
+ u_int16_t nsvci; /* uniquely identifies NS-VC at SGSN */
+
+ u_int32_t state;
+
+ struct timer_list alive_timer;
+ int timer_is_tns_alive;
+ int alive_retries;
+};
+
+/* FIXME: dynamically search for the matching NSVC */
+static struct gprs_nsvc dummy_nsvc = { .state = NSE_S_BLOCKED | NSE_S_ALIVE };
+
+/* Section 10.3.2, Table 13 */
+static const char *ns_cause_str[] = {
+ [NS_CAUSE_TRANSIT_FAIL] = "Transit network failure",
+ [NS_CAUSE_OM_INTERVENTION] = "O&M intervention",
+ [NS_CAUSE_EQUIP_FAIL] = "Equipment failure",
+ [NS_CAUSE_NSVC_BLOCKED] = "NS-VC blocked",
+ [NS_CAUSE_NSVC_UNKNOWN] = "NS-VC unknown",
+ [NS_CAUSE_BVCI_UNKNOWN] = "BVCI unknown",
+ [NS_CAUSE_SEM_INCORR_PDU] = "Semantically incorrect PDU",
+ [NS_CAUSE_PDU_INCOMP_PSTATE] = "PDU not compatible with protocol state",
+ [NS_CAUSE_PROTO_ERR_UNSPEC] = "Protocol error, unspecified",
+ [NS_CAUSE_INVAL_ESSENT_IE] = "Invalid essential IE",
+ [NS_CAUSE_MISSING_ESSENT_IE] = "Missing essential IE",
+};
+
+static const char *gprs_ns_cause_str(enum ns_cause cause)
+{
+ if (cause >= ARRAY_SIZE(ns_cause_str))
+ return "undefined";
+
+ if (ns_cause_str[cause])
+ return ns_cause_str[cause];
+
+ return "undefined";
+}
+
+static int gprs_ns_tx(struct msgb *msg)
+{
+ return ipac_gprs_send(msg);
+}
+
+static int gprs_ns_tx_simple(struct gprs_ns_link *link, u_int8_t pdu_type)
+{
+ struct msgb *msg = msgb_alloc(NS_ALLOC_SIZE, "GPRS/NS");
+ struct gprs_ns_hdr *nsh;
+
+ if (!msg)
+ return -ENOMEM;
+
+ nsh = (struct gprs_ns_hdr *) msgb_put(msg, sizeof(*nsh));
+
+ nsh->pdu_type = pdu_type;
+
+ return gprs_ns_tx(msg);
+}
+
+#define NS_TIMER_ALIVE 3, 0 /* after 3 seconds without response, we retry */
+#define NS_TIMER_TEST 30, 0 /* every 10 seconds we check if the BTS is still alive */
+#define NS_ALIVE_RETRIES 10 /* after 3 failed retransmit we declare BTS as dead */
+
+static void gprs_ns_alive_cb(void *data)
+{
+ struct gprs_nsvc *nsvc = data;
+
+ if (nsvc->timer_is_tns_alive) {
+ /* Tns-alive case: we expired without response ! */
+ nsvc->alive_retries++;
+ if (nsvc->alive_retries > NS_ALIVE_RETRIES) {
+ /* mark as dead and blocked */
+ nsvc->state = NSE_S_BLOCKED;
+ DEBUGP(DGPRS, "Tns-alive more then %u retries, "
+ " blocking NS-VC\n", NS_ALIVE_RETRIES);
+ /* FIXME: inform higher layers */
+ return;
+ }
+ } else {
+ /* Tns-test case: send NS-ALIVE PDU */
+ gprs_ns_tx_simple(NULL, NS_PDUT_ALIVE);
+ /* start Tns-alive timer */
+ nsvc->timer_is_tns_alive = 1;
+ }
+ bsc_schedule_timer(&nsvc->alive_timer, NS_TIMER_ALIVE);
+}
+
+/* Section 9.2.6 */
+static int gprs_ns_tx_reset_ack(u_int16_t nsvci, u_int16_t nsei)
+{
+ struct msgb *msg = msgb_alloc(NS_ALLOC_SIZE, "GPRS/NS");
+ struct gprs_ns_hdr *nsh;
+
+ if (!msg)
+ return -ENOMEM;
+
+ nsvci = htons(nsvci);
+ nsei = htons(nsei);
+
+ nsh = (struct gprs_ns_hdr *) msgb_put(msg, sizeof(*nsh));
+
+ nsh->pdu_type = NS_PDUT_RESET_ACK;
+
+ msgb_tvlv_put(msg, NS_IE_VCI, 2, (u_int8_t *)&nsvci);
+ msgb_tvlv_put(msg, NS_IE_NSEI, 2, (u_int8_t *)&nsei);
+
+ return gprs_ns_tx(msg);
+}
+
+/* Section 9.2.10: transmit side */
+int gprs_ns_sendmsg(struct gprs_ns_link *link, u_int16_t bvci,
+ struct msgb *msg)
+{
+ struct gprs_ns_hdr *nsh;
+
+ nsh = (struct gprs_ns_hdr *) msgb_push(msg, sizeof(*nsh) + 3);
+ if (!nsh) {
+ DEBUGP(DGPRS, "Not enough headroom for NS header\n");
+ return -EIO;
+ }
+
+ nsh->pdu_type = NS_PDUT_UNITDATA;
+ /* spare octet in data[0] */
+ nsh->data[1] = bvci >> 8;
+ nsh->data[2] = bvci & 0xff;
+
+ return gprs_ns_tx(msg);
+}
+
+/* Section 9.2.10: receive side */
+static int gprs_ns_rx_unitdata(struct msgb *msg)
+{
+ struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *)msg->l2h;
+ u_int16_t bvci;
+
+ /* spare octet in data[0] */
+ bvci = nsh->data[1] << 8 | nsh->data[2];
+ msg->l3h = &nsh->data[3];
+
+ /* call upper layer (BSSGP) */
+ return gprs_bssgp_rcvmsg(msg, bvci);
+}
+
+/* Section 9.2.7 */
+static int gprs_ns_rx_status(struct msgb *msg)
+{
+ struct gprs_ns_hdr *nsh = msg->l2h;
+ struct tlv_parsed tp;
+ u_int8_t cause;
+ int rc;
+
+ DEBUGP(DGPRS, "NS STATUS ");
+
+ rc = tlv_parse(&tp, &ns_att_tlvdef, nsh->data, msgb_l2len(msg), 0, 0);
+
+ if (!TLVP_PRESENT(&tp, NS_IE_CAUSE)) {
+ DEBUGPC(DGPRS, "missing cause IE\n");
+ return -EINVAL;
+ }
+
+ cause = *TLVP_VAL(&tp, NS_IE_CAUSE);
+ DEBUGPC(DGPRS, "cause=%s\n", gprs_ns_cause_str(cause));
+
+ return 0;
+}
+
+/* Section 7.3 */
+static int gprs_ns_rx_reset(struct msgb *msg)
+{
+ struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
+ struct gprs_nsvc *nsvc = &dummy_nsvc;
+ struct tlv_parsed tp;
+ u_int8_t *cause;
+ u_int16_t *nsvci, *nsei;
+ int rc;
+
+ DEBUGP(DGPRS, "NS RESET ");
+
+ rc = tlv_parse(&tp, &ns_att_tlvdef, nsh->data, msgb_l2len(msg), 0, 0);
+
+ if (!TLVP_PRESENT(&tp, NS_IE_CAUSE) ||
+ !TLVP_PRESENT(&tp, NS_IE_VCI) ||
+ !TLVP_PRESENT(&tp, NS_IE_NSEI)) {
+ /* FIXME: respond with NS_CAUSE_MISSING_ESSENT_IE */
+ DEBUGPC(DGPRS, "Missing mandatory IE\n");
+ return -EINVAL;
+ }
+
+ cause = (u_int8_t *) TLVP_VAL(&tp, NS_IE_CAUSE);
+ nsvci = (u_int16_t *) TLVP_VAL(&tp, NS_IE_VCI);
+ nsei = (u_int16_t *) TLVP_VAL(&tp, NS_IE_NSEI);
+
+ *nsvci = ntohs(*nsvci);
+ *nsei = ntohs(*nsei);
+
+ DEBUGPC(DGPRS, "cause=%s, NSVCI=%u, NSEI=%u\n",
+ gprs_ns_cause_str(*cause), *nsvci, *nsei);
+
+ /* mark the NS-VC as blocked and alive */
+ nsvc->state = NSE_S_BLOCKED | NSE_S_ALIVE;
+ nsvc->nsei = *nsei;
+ nsvc->nsvci = *nsvci;
+
+ /* start the test procedure */
+ nsvc->alive_timer.cb = gprs_ns_alive_cb;
+ nsvc->alive_timer.data = nsvc;
+ bsc_schedule_timer(&nsvc->alive_timer, NS_TIMER_ALIVE);
+
+ return gprs_ns_tx_reset_ack(*nsvci, *nsei);
+}
+
+/* main entry point, here incoming NS frames enter */
+int gprs_ns_rcvmsg(struct msgb *msg)
+{
+ struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
+ struct gprs_nsvc *nsvc = &dummy_nsvc;
+ int rc = 0;
+
+ switch (nsh->pdu_type) {
+ case NS_PDUT_ALIVE:
+ /* remote end inquires whether we're still alive,
+ * we need to respond with ALIVE_ACK */
+ rc = gprs_ns_tx_simple(NULL, NS_PDUT_ALIVE_ACK);
+ break;
+ case NS_PDUT_ALIVE_ACK:
+ /* stop Tns-alive */
+ bsc_del_timer(&nsvc->alive_timer);
+ /* start Tns-test */
+ nsvc->timer_is_tns_alive = 0;
+ bsc_schedule_timer(&nsvc->alive_timer, NS_TIMER_TEST);
+ break;
+ case NS_PDUT_UNITDATA:
+ /* actual user data */
+ rc = gprs_ns_rx_unitdata(msg);
+ break;
+ case NS_PDUT_STATUS:
+ rc = gprs_ns_rx_status(msg);
+ break;
+ case NS_PDUT_RESET:
+ rc = gprs_ns_rx_reset(msg);
+ break;
+ case NS_PDUT_RESET_ACK:
+ /* FIXME: mark remote NS-VC as blocked + active */
+ break;
+ case NS_PDUT_UNBLOCK:
+ /* Section 7.2: unblocking procedure */
+ DEBUGP(DGPRS, "NS UNBLOCK\n");
+ nsvc->state &= ~NSE_S_BLOCKED;
+ rc = gprs_ns_tx_simple(NULL, NS_PDUT_UNBLOCK_ACK);
+ break;
+ case NS_PDUT_UNBLOCK_ACK:
+ /* FIXME: mark remote NS-VC as unblocked + active */
+ break;
+ case NS_PDUT_BLOCK:
+ DEBUGP(DGPRS, "NS BLOCK\n");
+ nsvc->state |= NSE_S_BLOCKED;
+ rc = gprs_ns_tx_simple(NULL, NS_PDUT_UNBLOCK_ACK);
+ break;
+ case NS_PDUT_BLOCK_ACK:
+ /* FIXME: mark remote NS-VC as blocked + active */
+ break;
+ default:
+ DEBUGP(DGPRS, "Unknown NS PDU type 0x%02x\n", nsh->pdu_type);
+ rc = -EINVAL;
+ break;
+ }
+ return rc;
+}
+