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/* GPRS BSSGP protocol implementation as per 3GPP TS 08.18 */
/* (C) 2009-2010 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.
*
*/
#include <errno.h>
#include <stdint.h>
#include <netinet/in.h>
#include <osmocore/msgb.h>
#include <osmocore/tlv.h>
#include <osmocore/talloc.h>
#include <openbsc/debug.h>
#include <openbsc/gsm_data.h>
#include <openbsc/gsm_04_08_gprs.h>
#include <openbsc/gprs_bssgp.h>
#include <openbsc/gprs_llc.h>
#include <openbsc/gprs_ns.h>
/* global pointer to the gsm network data structure */
/* FIXME: this must go! */
extern struct gsm_network *bsc_gsmnet;
void *bssgp_tall_ctx = NULL;
/* Our actual implementation */
#define BVC_F_BLOCKED 0x0001
/* The per-BTS context that we keep on the SGSN side of the BSSGP link */
struct bssgp_bts_ctx {
struct llist_head list;
/* parsed RA ID and Cell ID of the remote BTS */
struct gprs_ra_id ra_id;
uint16_t cell_id;
/* NSEI and BVCI of underlying Gb link. Together they
* uniquely identify a link to a BTS (5.4.4) */
uint16_t bvci;
uint16_t nsei;
uint32_t bvc_state;
/* we might want to add this as a shortcut later, avoiding the NSVC
* lookup for every packet, similar to a routing cache */
//struct gprs_nsvc *nsvc;
};
LLIST_HEAD(bts_ctxts);
/* Find a BTS Context based on parsed RA ID and Cell ID */
struct bssgp_bts_ctx *btsctx_by_raid_cid(const struct gprs_ra_id *raid, uint16_t cid)
{
struct bssgp_bts_ctx *bctx;
llist_for_each_entry(bctx, &bts_ctxts, list) {
if (!memcmp(&bctx->ra_id, raid, sizeof(bctx->ra_id)) &&
bctx->cell_id == cid)
return bctx;
}
return NULL;
}
/* Find a BTS context based on BVCI+NSEI tuple */
struct bssgp_bts_ctx *btsctx_by_bvci_nsei(uint16_t bvci, uint16_t nsei)
{
struct bssgp_bts_ctx *bctx;
llist_for_each_entry(bctx, &bts_ctxts, list) {
if (bctx->nsei == nsei && bctx->bvci == bvci)
return bctx;
}
return NULL;
}
struct bssgp_btx_ctx *btsctx_alloc(uint16_t bvci, uint16_t nsei)
{
struct bssgp_bts_ctx *ctx;
ctx = talloc_zero(bssgp_tall_ctx, struct bssgp_bts_ctx);
if (!ctx)
return NULL;
ctx->bvci = bvci;
ctx->nsei = nsei;
llist_add(&ctx->list, &bts_ctxts);
return ctx;
}
/* Chapter 10.4.5: Flow Control BVC ACK */
static int bssgp_tx_fc_bvc_ack(uint16_t nsei, uint8_t tag, uint16_t ns_bvci)
{
struct msgb *msg = bssgp_msgb_alloc();
struct bssgp_normal_hdr *bgph =
(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
msgb_nsei(msg) = nsei;
msgb_bvci(msg) = ns_bvci;
bgph->pdu_type = BSSGP_PDUT_FLOW_CONTROL_BVC_ACK;
msgb_tvlv_put(msg, BSSGP_IE_TAG, 1, &tag);
return gprs_ns_sendmsg(bssgp_nsi, msg);
}
uint16_t bssgp_parse_cell_id(struct gprs_ra_id *raid, const uint8_t *buf)
{
/* 6 octets RAC */
gsm48_parse_ra(raid, buf);
/* 2 octets CID */
return ntohs(*(uint16_t *) (buf+6));
}
/* Chapter 8.4 BVC-Reset Procedure */
static int bssgp_rx_bvc_reset(struct msgb *msg, struct tlv_parsed *tp,
uint16_t ns_bvci)
{
struct bssgp_bts_ctx *bctx;
uint16_t nsei = msgb_nsei(msg);
uint16_t bvci;
int rc;
bvci = ntohs(*(uint16_t *)TLVP_VAL(tp, BSSGP_IE_BVCI));
DEBUGPC(DBSSGP, "BVCI=%u, cause=%s\n", bvci,
bssgp_cause_str(*TLVP_VAL(tp, BSSGP_IE_CAUSE)));
/* look-up or create the BTS context for this BVC */
bctx = btsctx_by_bvci_nsei(bvci, nsei);
if (!bctx)
bctx = btsctx_alloc(bvci, nsei);
/* When we receive a BVC-RESET PDU (at least of a PTP BVCI), the BSS
* informs us about its RAC + Cell ID, so we can create a mapping */
if (bvci != 0 && bvci != 1) {
if (!TLVP_PRESENT(tp, BSSGP_IE_CELL_ID)) {
LOGP(DBSSGP, LOGL_ERROR, "BSSGP RESET BVCI=%u "
"missing mandatory IE\n", bvci);
return -EINVAL;
}
/* actually extract RAC / CID */
bctx->cell_id = bssgp_parse_cell_id(&bctx->ra_id,
TLVP_VAL(tp, BSSGP_IE_CELL_ID));
LOGP(DBSSGP, LOGL_NOTICE, "Cell %u-%u-%u-%u CI %u on BVCI %u\n",
bctx->ra_id.mcc, bctx->ra_id.mnc, bctx->ra_id.lac,
bctx->ra_id.rac, bctx->cell_id, bvci);
}
/* Acknowledge the RESET to the BTS */
rc = bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_RESET_ACK,
nsei, bvci, ns_bvci);
return 0;
}
/* Uplink unit-data */
static int bssgp_rx_ul_ud(struct msgb *msg)
{
struct bssgp_ud_hdr *budh = (struct bssgp_ud_hdr *) msgb_bssgph(msg);
int data_len = msgb_bssgp_len(msg) - sizeof(*budh);
struct tlv_parsed tp;
int rc;
DEBUGP(DBSSGP, "BSSGP UL-UD\n");
/* extract TLLI and parse TLV IEs */
msgb_tlli(msg) = ntohl(budh->tlli);
rc = bssgp_tlv_parse(&tp, budh->data, data_len);
/* Cell ID and LLC_PDU are the only mandatory IE */
if (!TLVP_PRESENT(&tp, BSSGP_IE_CELL_ID) ||
!TLVP_PRESENT(&tp, BSSGP_IE_LLC_PDU))
return -EIO;
/* FIXME: lookup bssgp_bts_ctx based on BVCI + NSEI */
/* store pointer to LLC header and CELL ID in msgb->cb */
msgb_llch(msg) = TLVP_VAL(&tp, BSSGP_IE_LLC_PDU);
msgb_bcid(msg) = TLVP_VAL(&tp, BSSGP_IE_CELL_ID);
return gprs_llc_rcvmsg(msg, &tp);
}
static int bssgp_rx_suspend(struct msgb *msg)
{
struct bssgp_normal_hdr *bgph =
(struct bssgp_normal_hdr *) msgb_bssgph(msg);
int data_len = msgb_bssgp_len(msg) - sizeof(*bgph);
struct tlv_parsed tp;
int rc;
DEBUGP(DBSSGP, "BSSGP SUSPEND\n");
rc = bssgp_tlv_parse(&tp, bgph->data, data_len);
if (rc < 0)
return rc;
if (!TLVP_PRESENT(&tp, BSSGP_IE_TLLI) ||
!TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA))
return -EIO;
/* FIXME: pass the SUSPEND request to GMM */
/* SEND SUSPEND_ACK or SUSPEND_NACK */
}
static int bssgp_rx_resume(struct msgb *msg)
{
struct bssgp_normal_hdr *bgph =
(struct bssgp_normal_hdr *) msgb_bssgph(msg);
int data_len = msgb_bssgp_len(msg) - sizeof(*bgph);
struct tlv_parsed tp;
int rc;
DEBUGP(DBSSGP, "BSSGP RESUME\n");
rc = bssgp_tlv_parse(&tp, bgph->data, data_len);
if (rc < 0)
return rc;
if (!TLVP_PRESENT(&tp, BSSGP_IE_TLLI) ||
!TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA) ||
!TLVP_PRESENT(&tp, BSSGP_IE_SUSPEND_REF_NR))
return -EIO;
/* FIXME: pass the RESUME request to GMM */
/* SEND RESUME_ACK or RESUME_NACK */
}
static int bssgp_rx_fc_bvc(struct msgb *msg, struct tlv_parsed *tp)
{
DEBUGP(DBSSGP, "BSSGP FC BVC\n");
if (!TLVP_PRESENT(tp, BSSGP_IE_TAG) ||
!TLVP_PRESENT(tp, BSSGP_IE_BVC_BUCKET_SIZE) ||
!TLVP_PRESENT(tp, BSSGP_IE_BUCKET_LEAK_RATE) ||
!TLVP_PRESENT(tp, BSSGP_IE_BMAX_DEFAULT_MS) ||
!TLVP_PRESENT(tp, BSSGP_IE_R_DEFAULT_MS))
return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
/* FIXME: actually implement flow control */
/* Send FLOW_CONTROL_BVC_ACK */
return bssgp_tx_fc_bvc_ack(msgb_nsei(msg), *TLVP_VAL(tp, BSSGP_IE_TAG),
msgb_bvci(msg));
}
/* We expect msgb_bssgph() to point to the BSSGP header */
int gprs_bssgp_rcvmsg(struct msgb *msg)
{
struct bssgp_normal_hdr *bgph =
(struct bssgp_normal_hdr *) msgb_bssgph(msg);
struct tlv_parsed tp;
uint8_t pdu_type = bgph->pdu_type;
int data_len = msgb_bssgp_len(msg) - sizeof(*bgph);
uint16_t bvci; /* PTP BVCI */
uint16_t ns_bvci = msgb_bvci(msg);
int rc = 0;
/* Identifiers from DOWN: NSEI, BVCI (both in msg->cb) */
/* UNITDATA BSSGP headers have TLLI in front */
if (pdu_type != BSSGP_PDUT_UL_UNITDATA &&
pdu_type != BSSGP_PDUT_DL_UNITDATA)
rc = bssgp_tlv_parse(&tp, bgph->data, data_len);
switch (pdu_type) {
case BSSGP_PDUT_UL_UNITDATA:
/* some LLC data from the MS */
rc = bssgp_rx_ul_ud(msg);
break;
case BSSGP_PDUT_RA_CAPABILITY:
/* BSS requests RA capability or IMSI */
DEBUGP(DBSSGP, "BSSGP RA CAPABILITY UPDATE\n");
/* FIXME: send RA_CAPA_UPDATE_ACK */
break;
case BSSGP_PDUT_RADIO_STATUS:
DEBUGP(DBSSGP, "BSSGP RADIO STATUS\n");
/* BSS informs us of some exception */
/* FIXME: notify GMM */
break;
case BSSGP_PDUT_SUSPEND:
/* MS wants to suspend */
rc = bssgp_rx_suspend(msg);
break;
case BSSGP_PDUT_RESUME:
/* MS wants to resume */
rc = bssgp_rx_resume(msg);
break;
case BSSGP_PDUT_FLUSH_LL:
/* BSS informs MS has moved to one cell to other cell */
DEBUGP(DBSSGP, "BSSGP FLUSH LL\n");
/* FIXME: notify GMM */
/* Send FLUSH_LL_ACK */
break;
case BSSGP_PDUT_LLC_DISCARD:
/* BSS informs that some LLC PDU's have been discarded */
DEBUGP(DBSSGP, "BSSGP LLC DISCARDED\n");
/* FIXME: notify GMM */
break;
case BSSGP_PDUT_FLOW_CONTROL_BVC:
/* BSS informs us of available bandwidth in Gb interface */
rc = bssgp_rx_fc_bvc(msg, &tp);
break;
case BSSGP_PDUT_FLOW_CONTROL_MS:
/* BSS informs us of available bandwidth to one MS */
DEBUGP(DBSSGP, "BSSGP FC MS\n");
/* FIXME: actually implement flow control */
/* FIXME: Send FLOW_CONTROL_MS_ACK */
break;
case BSSGP_PDUT_BVC_BLOCK:
/* BSS tells us that BVC shall be blocked */
DEBUGP(DBSSGP, "BSSGP BVC BLOCK ");
if (!TLVP_PRESENT(&tp, BSSGP_IE_BVCI) ||
!TLVP_PRESENT(&tp, BSSGP_IE_CAUSE))
goto err_mand_ie;
bvci = ntohs(*(uint16_t *)TLVP_VAL(&tp, BSSGP_IE_BVCI));
DEBUGPC(DBSSGP, "BVCI=%u, cause=%s\n", bvci,
bssgp_cause_str(*TLVP_VAL(&tp, BSSGP_IE_CAUSE)));
/* We always acknowledge the BLOCKing */
rc = bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_BLOCK_ACK,
msgb_nsei(msg), bvci, ns_bvci);
break;
case BSSGP_PDUT_BVC_UNBLOCK:
/* BSS tells us that BVC shall be unblocked */
DEBUGP(DBSSGP, "BSSGP BVC UNBLOCK ");
if (!TLVP_PRESENT(&tp, BSSGP_IE_BVCI))
goto err_mand_ie;
bvci = ntohs(*(uint16_t *)TLVP_VAL(&tp, BSSGP_IE_BVCI));
DEBUGPC(DBSSGP, "BVCI=%u\n", bvci);
/* We always acknowledge the unBLOCKing */
rc = bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_UNBLOCK_ACK,
msgb_nsei(msg), bvci, ns_bvci);
break;
case BSSGP_PDUT_BVC_RESET:
/* BSS tells us that BVC init is required */
DEBUGP(DBSSGP, "BSSGP BVC RESET ");
if (!TLVP_PRESENT(&tp, BSSGP_IE_BVCI) ||
!TLVP_PRESENT(&tp, BSSGP_IE_CAUSE))
goto err_mand_ie;
rc = bssgp_rx_bvc_reset(msg, &tp, ns_bvci);
break;
case BSSGP_PDUT_STATUS:
/* Some exception has occurred */
/* FIXME: notify GMM */
case BSSGP_PDUT_DOWNLOAD_BSS_PFC:
case BSSGP_PDUT_CREATE_BSS_PFC_ACK:
case BSSGP_PDUT_CREATE_BSS_PFC_NACK:
case BSSGP_PDUT_MODIFY_BSS_PFC:
case BSSGP_PDUT_DELETE_BSS_PFC_ACK:
DEBUGP(DBSSGP, "BSSGP PDU type 0x%02x not [yet] implemented\n",
pdu_type);
break;
/* those only exist in the SGSN -> BSS direction */
case BSSGP_PDUT_DL_UNITDATA:
case BSSGP_PDUT_PAGING_PS:
case BSSGP_PDUT_PAGING_CS:
case BSSGP_PDUT_RA_CAPA_UPDATE_ACK:
case BSSGP_PDUT_SUSPEND_ACK:
case BSSGP_PDUT_SUSPEND_NACK:
case BSSGP_PDUT_RESUME_ACK:
case BSSGP_PDUT_RESUME_NACK:
case BSSGP_PDUT_FLUSH_LL_ACK:
case BSSGP_PDUT_FLOW_CONTROL_BVC_ACK:
case BSSGP_PDUT_FLOW_CONTROL_MS_ACK:
case BSSGP_PDUT_BVC_BLOCK_ACK:
case BSSGP_PDUT_BVC_UNBLOCK_ACK:
case BSSGP_PDUT_SGSN_INVOKE_TRACE:
DEBUGP(DBSSGP, "BSSGP PDU type 0x%02x only exists in DL\n",
pdu_type);
rc = -EINVAL;
break;
default:
DEBUGP(DBSSGP, "BSSGP PDU type 0x%02x unknown\n", pdu_type);
break;
}
return rc;
err_mand_ie:
return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
}
/* Entry function from upper level (LLC), asking us to transmit a BSSGP PDU
* to a remote MS (identified by TLLI) at a BTS identified by its BVCI and NSEI */
int gprs_bssgp_tx_dl_ud(struct msgb *msg)
{
struct bssgp_bts_ctx *bctx;
struct bssgp_ud_hdr *budh;
uint8_t llc_pdu_tlv_hdr_len = 2;
uint8_t *llc_pdu_tlv, *qos_profile;
uint16_t pdu_lifetime = 1000; /* centi-seconds */
uint8_t qos_profile_default[3] = { 0x00, 0x00, 0x21 };
uint16_t msg_len = msg->len;
uint16_t bvci = msgb_bvci(msg);
uint16_t nsei = msgb_nsei(msg);
/* Identifiers from UP: TLLI, BVCI, NSEI (all in msgb->cb) */
if (bvci < 2) {
LOGP(DBSSGP, LOGL_ERROR, "Cannot send DL-UD to BVCI %u\n",
bvci);
return -EINVAL;
}
bctx = btsctx_by_bvci_nsei(bvci, nsei);
if (!bctx)
bctx = btsctx_alloc(bvci, nsei);
if (msg->len > TVLV_MAX_ONEBYTE)
llc_pdu_tlv_hdr_len += 1;
/* prepend the tag and length of the LLC-PDU TLV */
llc_pdu_tlv = msgb_push(msg, llc_pdu_tlv_hdr_len);
llc_pdu_tlv[0] = BSSGP_IE_LLC_PDU;
if (llc_pdu_tlv_hdr_len > 2) {
llc_pdu_tlv[1] = msg_len >> 8;
llc_pdu_tlv[2] = msg_len & 0xff;
} else {
llc_pdu_tlv[1] = msg_len & 0x3f;
llc_pdu_tlv[1] |= 0x80;
}
/* FIXME: optional elements */
/* prepend the pdu lifetime */
pdu_lifetime = htons(pdu_lifetime);
msgb_tvlv_push(msg, BSSGP_IE_PDU_LIFETIME, 2, (uint8_t *)&pdu_lifetime);
/* prepend the QoS profile, TLLI and pdu type */
budh = (struct bssgp_ud_hdr *) msgb_push(msg, sizeof(*budh));
memcpy(budh->qos_profile, qos_profile_default, sizeof(qos_profile_default));
budh->tlli = htonl(msgb_tlli(msg));
budh->pdu_type = BSSGP_PDUT_DL_UNITDATA;
/* Identifiers down: BVCI, NSEI (in msgb->cb) */
return gprs_ns_sendmsg(bssgp_nsi, msg);
}
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