diff options
Diffstat (limited to 'openbsc/src/gprs_ns.c')
-rw-r--r-- | openbsc/src/gprs_ns.c | 348 |
1 files changed, 348 insertions, 0 deletions
diff --git a/openbsc/src/gprs_ns.c b/openbsc/src/gprs_ns.c new file mode 100644 index 00000000..a686a22a --- /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; +} + |