Currently sending SUSPEND/RESUME messages to this function (like it
is done in the osmo-sgsn) results in STATUS messages complaining
about an unknown BVCI. The reason is, that these messages rely on a
TLLI/RAI pair to identify the context and do not contain an explicit
BVCI.

This patch modifies bssgp_rcvmsg() to only complain about and unknown
BVCI if one is given but a matching context is not found (except for
RESET messages). The ctx argument is removed from the functions
handling SUSPEND and RESUME since it will always be NULL then.

TODO:
  - test cases
  - end-to-end test

Sponsored-by: On-Waves ehf
---
 src/gb/gprs_bssgp.c | 43 +++++++++++++++++++++++++------------------
 1 file changed, 25 insertions(+), 18 deletions(-)

diff --git a/src/gb/gprs_bssgp.c b/src/gb/gprs_bssgp.c
index 0e9fd38..eee638c 100644
--- a/src/gb/gprs_bssgp.c
+++ b/src/gb/gprs_bssgp.c
@@ -398,32 +398,32 @@ static int bssgp_rx_ul_ud(struct msgb *msg, struct 
tlv_parsed *tp,
        return bssgp_prim_cb(&gbp.oph, NULL);
 }
 
-static int bssgp_rx_suspend(struct msgb *msg, struct tlv_parsed *tp,
-                           struct bssgp_bvc_ctx *ctx)
+static int bssgp_rx_suspend(struct msgb *msg, struct tlv_parsed *tp)
 {
        struct osmo_bssgp_prim gbp;
        struct gprs_ra_id raid;
        uint32_t tlli;
+       uint16_t ns_bvci = msgb_bvci(msg);
        int rc;
 
        if (!TLVP_PRESENT(tp, BSSGP_IE_TLLI) ||
            !TLVP_PRESENT(tp, BSSGP_IE_ROUTEING_AREA)) {
                LOGP(DBSSGP, LOGL_ERROR, "BSSGP BVCI=%u Rx SUSPEND "
-                       "missing mandatory IE\n", ctx->bvci);
+                       "missing mandatory IE\n", ns_bvci);
                return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
        }
 
        tlli = ntohl(*(uint32_t *)TLVP_VAL(tp, BSSGP_IE_TLLI));
 
        DEBUGP(DBSSGP, "BSSGP BVCI=%u TLLI=0x%08x Rx SUSPEND\n",
-               ctx->bvci, tlli);
+               ns_bvci, tlli);
 
        gsm48_parse_ra(&raid, TLVP_VAL(tp, BSSGP_IE_ROUTEING_AREA));
 
        /* Inform GMM about the SUSPEND request */
        memset(&gbp, 0, sizeof(gbp));
        gbp.nsei = msgb_nsei(msg);
-       gbp.bvci = ctx->bvci;
+       gbp.bvci = ns_bvci;
        gbp.tlli = tlli;
        gbp.ra_id = &raid;
        osmo_prim_init(&gbp.oph, SAP_BSSGP_GMM, PRIM_BSSGP_GMM_SUSPEND,
@@ -438,34 +438,34 @@ static int bssgp_rx_suspend(struct msgb *msg, struct 
tlv_parsed *tp,
        return 0;
 }
 
-static int bssgp_rx_resume(struct msgb *msg, struct tlv_parsed *tp,
-                          struct bssgp_bvc_ctx *ctx)
+static int bssgp_rx_resume(struct msgb *msg, struct tlv_parsed *tp)
 {
        struct osmo_bssgp_prim gbp;
        struct gprs_ra_id raid;
        uint32_t tlli;
        uint8_t suspend_ref;
+       uint16_t ns_bvci = msgb_bvci(msg);
        int rc;
 
        if (!TLVP_PRESENT(tp, BSSGP_IE_TLLI) ||
            !TLVP_PRESENT(tp, BSSGP_IE_ROUTEING_AREA) ||
            !TLVP_PRESENT(tp, BSSGP_IE_SUSPEND_REF_NR)) {
                LOGP(DBSSGP, LOGL_ERROR, "BSSGP BVCI=%u Rx RESUME "
-                       "missing mandatory IE\n", ctx->bvci);
+                       "missing mandatory IE\n", ns_bvci);
                return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
        }
 
        tlli = ntohl(*(uint32_t *)TLVP_VAL(tp, BSSGP_IE_TLLI));
        suspend_ref = *TLVP_VAL(tp, BSSGP_IE_SUSPEND_REF_NR);
 
-       DEBUGP(DBSSGP, "BSSGP BVCI=%u TLLI=0x%08x Rx RESUME\n", ctx->bvci, 
tlli);
+       DEBUGP(DBSSGP, "BSSGP BVCI=%u TLLI=0x%08x Rx RESUME\n", ns_bvci, tlli);
 
        gsm48_parse_ra(&raid, TLVP_VAL(tp, BSSGP_IE_ROUTEING_AREA));
 
        /* Inform GMM about the RESUME request */
        memset(&gbp, 0, sizeof(gbp));
        gbp.nsei = msgb_nsei(msg);
-       gbp.bvci = ctx->bvci;
+       gbp.bvci = ns_bvci;
        gbp.tlli = tlli;
        gbp.ra_id = &raid;
        gbp.u.resume.suspend_ref = suspend_ref;
@@ -885,23 +885,26 @@ static int bssgp_rx_sign(struct msgb *msg, struct 
tlv_parsed *tp,
        uint8_t pdu_type = bgph->pdu_type;
        int rc = 0;
        uint16_t ns_bvci = msgb_bvci(msg);
+       uint16_t bvci = bctx ? bctx->bvci : ns_bvci;
 
        switch (bgph->pdu_type) {
        case BSSGP_PDUT_SUSPEND:
                /* MS wants to suspend */
-               rc = bssgp_rx_suspend(msg, tp, bctx);
+               rc = bssgp_rx_suspend(msg, tp);
                break;
        case BSSGP_PDUT_RESUME:
                /* MS wants to resume */
-               rc = bssgp_rx_resume(msg, tp, bctx);
+               rc = bssgp_rx_resume(msg, tp);
                break;
        case BSSGP_PDUT_FLUSH_LL_ACK:
                /* BSS informs us it has performed LL FLUSH */
-               DEBUGP(DBSSGP, "BSSGP Rx BVCI=%u FLUSH LL ACK\n", bctx->bvci);
+               DEBUGP(DBSSGP, "BSSGP Rx BVCI=%u FLUSH LL ACK\n", bvci);
                /* FIXME: send NM_FLUSH_LL.res to NM */
                break;
        case BSSGP_PDUT_LLC_DISCARD:
                /* BSS informs that some LLC PDU's have been discarded */
+               if (!bctx)
+                       goto err_no_bvci;
                rc = bssgp_rx_llc_disc(msg, tp, bctx);
                break;
        case BSSGP_PDUT_BVC_BLOCK:
@@ -935,7 +938,7 @@ static int bssgp_rx_sign(struct msgb *msg, struct 
tlv_parsed *tp,
                break;
        case BSSGP_PDUT_STATUS:
                /* Some exception has occurred */
-               DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx BVC STATUS\n", bctx->bvci);
+               DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx BVC STATUS\n", bvci);
                /* FIXME: send NM_STATUS.ind to NM */
                break;
        /* those only exist in the SGSN -> BSS direction */
@@ -950,18 +953,20 @@ static int bssgp_rx_sign(struct msgb *msg, struct 
tlv_parsed *tp,
        case BSSGP_PDUT_BVC_UNBLOCK_ACK:
        case BSSGP_PDUT_SGSN_INVOKE_TRACE:
                DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx PDU type 0x%02x only exists "
-                       "in DL\n", bctx->bvci, pdu_type);
+                       "in DL\n", bvci, pdu_type);
                bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, msg);
                rc = -EINVAL;
                break;
        default:
                DEBUGP(DBSSGP, "BSSGP BVCI=%u Rx PDU type 0x%02x unknown\n",
-                       bctx->bvci, pdu_type);
+                       bvci, pdu_type);
                rc = bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, msg);
                break;
        }
 
        return rc;
+err_no_bvci:
+       LOGP(DBSSGP, LOGL_ERROR, "BSSGP missing mandatory BVCI\n");
 err_mand_ie:
        return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
 }
@@ -997,8 +1002,10 @@ int bssgp_rcvmsg(struct msgb *msg)
 
        /* look-up or create the BTS context for this BVC */
        bctx = btsctx_by_bvci_nsei(bvci, msgb_nsei(msg));
-       /* Only a RESET PDU can create a new BVC context */
-       if (!bctx && pdu_type != BSSGP_PDUT_BVC_RESET) {
+       /* Only a RESET PDU can create a new BVC context,
+        * otherwise it must be registered if a BVCI is given */
+       if (!bctx && bvci != BVCI_SIGNALLING &&
+           pdu_type != BSSGP_PDUT_BVC_RESET) {
                LOGP(DBSSGP, LOGL_NOTICE, "NSEI=%u/BVCI=%u Rejecting PDU "
                        "type %u for unknown BVCI\n", msgb_nsei(msg), bvci,
                        pdu_type);
-- 
1.9.1


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