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[gprs] introduce BSSGP concept of BTS contextx 

A BTS context represents the mapping betewen (RA-ID, Cell-ID) and
(BVCI, NSEI) as well as the per-BVC local state.
This commit is contained in:
Harald Welte 2010-05-02 09:23:16 +02:00
parent 288be16587
commit 6557cd0517
1 changed files with 110 additions and 23 deletions
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133
openbsc/src/gprs_bssgp.c
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@ -1,6 +1,6 @@
/* GPRS BSSGP protocol implementation as per 3GPP TS 08.18 */
/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
/* (C) 2009-2010 by Harald Welte <laforge@gnumonks.org>
*
* All Rights Reserved
*
@ -27,6 +27,8 @@
#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>
@ -39,6 +41,8 @@
extern struct gsm_network *bsc_gsmnet;
struct gprs_ns_inst *bssgp_nsi;
void *bssgp_tall_ctx = NULL;
/* Chapter 11.3.9 / Table 11.10: Cause coding */
static const char *bssgp_cause_strings[] = {
[BSSGP_CAUSE_PROC_OVERLOAD] = "Processor overload",
@ -74,6 +78,68 @@ static const char *bssgp_cause_str(enum gprs_bssgp_cause cause)
return "undefined";
}
#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;
}
static inline struct msgb *bssgp_msgb_alloc(void)
{
return msgb_alloc_headroom(4096, 128, "BSSGP");
@ -138,22 +204,52 @@ int bssgp_tx_status(u_int8_t cause, u_int16_t *bvci, struct msgb *orig_msg)
return gprs_ns_sendmsg(bssgp_nsi, msg);
}
static void bssgp_parse_cell_id(struct gprs_ra_id *raid, uint16_t *cid,
const uint8_t *buf)
{
/* 6 octets RAC */
gsm48_parse_ra(raid, buf);
/* 2 octets CID */
*cid = 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)
{
uint8_t bvci;
struct bssgp_bts_ctx *bctx;
uint16_t nsei = msgb_nsei(msg);
uint16_t bvci;
int rc;
bvci = ntohs(*(u_int16_t *)TLVP_VAL(tp, BSSGP_IE_BVCI));
DEBUGPC(DGPRS, "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(DGPRS, LOGL_ERROR, "BSSGP RESET BVCI=%u "
"missing mandatory IE\n", bvci);
return -EINVAL;
}
/* actually extract RAC / CID */
bssgp_parse_cell_id(&bctx->ra_id, &bctx->cell_id,
TLVP_VAL(tp, BSSGP_IE_CELL_ID));
LOGP(DGPRS, 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,
msgb_nsei(msg), bvci, ns_bvci);
nsei, bvci, ns_bvci);
return 0;
}
@ -161,13 +257,13 @@ static int bssgp_rx_bvc_reset(struct msgb *msg, struct tlv_parsed *tp,
static int bssgp_rx_ul_ud(struct msgb *msg, u_int16_t bvci)
{
struct bssgp_ud_hdr *budh = (struct bssgp_ud_hdr *) msg->l3h;
struct gsm_bts *bts;
int data_len = msgb_l3len(msg) - sizeof(*budh);
struct tlv_parsed tp;
int rc;
DEBUGP(DGPRS, "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);
@ -176,15 +272,6 @@ static int bssgp_rx_ul_ud(struct msgb *msg, u_int16_t bvci)
!TLVP_PRESENT(&tp, BSSGP_IE_LLC_PDU))
return -EIO;
#if 0 //FIXME
/* Determine the BTS based on the Cell ID */
bts = gsm48_bts_by_ra_id(bsc_gsmnet,
TLVP_VAL(&tp, BSSGP_IE_CELL_ID),
TLVP_LEN(&tp, BSSGP_IE_CELL_ID));
#endif
if (bts)
msg->trx = bts->c0;
msgb_llch(msg) = TLVP_VAL(&tp, BSSGP_IE_LLC_PDU);
return gprs_llc_rcvmsg(msg, &tp);
@ -261,6 +348,7 @@ int gprs_bssgp_rcvmsg(struct msgb *msg, u_int16_t ns_bvci)
u_int16_t bvci;
int rc = 0;
/* 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);
@ -314,6 +402,7 @@ int gprs_bssgp_rcvmsg(struct msgb *msg, u_int16_t ns_bvci)
bvci = ntohs(*(u_int16_t *)TLVP_VAL(&tp, BSSGP_IE_BVCI));
DEBUGPC(DGPRS, "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;
@ -324,6 +413,7 @@ int gprs_bssgp_rcvmsg(struct msgb *msg, u_int16_t ns_bvci)
goto err_mand_ie;
bvci = ntohs(*(u_int16_t *)TLVP_VAL(&tp, BSSGP_IE_BVCI));
DEBUGPC(DGPRS, "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;
@ -374,9 +464,11 @@ err_mand_ie:
return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
}
int gprs_bssgp_tx_dl_ud(struct msgb *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 RAC and CID */
int gprs_bssgp_tx_dl_ud(struct msgb *msg, const struct gprs_ra_id *raid, uint16_t cid)
{
struct gsm_bts *bts;
struct bssgp_bts_ctx *bctx;
struct bssgp_ud_hdr *budh;
u_int8_t llc_pdu_tlv_hdr_len = 2;
u_int8_t *llc_pdu_tlv, *qos_profile;
@ -384,12 +476,7 @@ int gprs_bssgp_tx_dl_ud(struct msgb *msg)
u_int8_t qos_profile_default[3] = { 0x00, 0x00, 0x21 };
u_int16_t msg_len = msg->len;
if (!msg->trx) {
DEBUGP(DGPRS, "Cannot transmit DL-UD without TRX assigned\n");
return -EINVAL;
}
bts = msg->trx->bts;
bctx = btsctx_by_raid_cid(raid, cid);
if (msg->len > TVLV_MAX_ONEBYTE)
llc_pdu_tlv_hdr_len += 1;
@ -417,8 +504,8 @@ int gprs_bssgp_tx_dl_ud(struct msgb *msg)
budh->tlli = htonl(msgb_tlli(msg));
budh->pdu_type = BSSGP_PDUT_DL_UNITDATA;
msgb_nsei(msg) = bts->gprs.nse.nsei;
msgb_bvci(msg) = bts->gprs.cell.bvci;
msgb_nsei(msg) = bctx->nsei;
msgb_bvci(msg) = bctx->bvci;
return gprs_ns_sendmsg(bssgp_nsi, msg);
}