[S] Change in osmo-sgsn[master]: Modified to dynamically adjust the returned QoS length to ensure comp...

[pespin]

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pespin has posted comments on this change by canghaiwuhen. ( 
https://gerrit.osmocom.org/c/osmo-sgsn/+/41948?usp=email )

Change subject: Modified to dynamically adjust the returned QoS length to 
ensure compatibility with older modules.
......................................................................


Patch Set 6:

(1 comment)

File src/sgsn/gprs_sm.c:

https://gerrit.osmocom.org/c/osmo-sgsn/+/41948/comment/e827c978_201c8e07?usp=email
 :
PS6, Line 339:  pdp->req_qos_len = TLVP_LEN(tp, OSMO_IE_GSM_REQ_QOS);
I just noticed that all the tp copying is done in sgsn_create_pdp_ctx() being 
called above, so this line should be moved there.

Actually, the QoS is being copied there, also the length, so afaict there's no 
need to store the length yet again in another variable?

See this code from that function:

        /* QoS options from GMM or remote */
        if (TLVP_LEN(tp, OSMO_IE_GSM_SUB_QOS) > 0) {
                qos_len = TLVP_LEN(tp, OSMO_IE_GSM_SUB_QOS);
                qos = TLVP_VAL(tp, OSMO_IE_GSM_SUB_QOS);
        } else {
                qos_len = TLVP_LEN(tp, OSMO_IE_GSM_REQ_QOS);
                qos = TLVP_VAL(tp, OSMO_IE_GSM_REQ_QOS);
        }
        pdp->qos_req.l = qos_len + 1;
        if (pdp->qos_req.l > sizeof(pdp->qos_req.v))
                pdp->qos_req.l = sizeof(pdp->qos_req.v);
        pdp->qos_req.v[0] = 0; /* Allocation/Retention policy */
        memcpy(&pdp->qos_req.v[1], qos, pdp->qos_req.l - 1);

So you probably need to use "pdp->qos_req.l - 1" (because the GTP QoS has an 
extra byte prepended for allocation/retention policy).



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