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