GPRS/GMM: Correctly look up MM Context in RA Update
If a MS changes RA, the RA will arrive in the new cell using the old
TLLI (masked as foreign TLLI). So we need to look-up the TLLI
in a special way, using the old RA as indicated in the 04.08 GMM
message.
There is still another bug remaining: As we somehow create a new LLC,
the sequence numbers of our responses start from 0 again, which is not
what the MS expects. This needs to be fixed in a follow-up patch.
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index 817092e..82a4ca8 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -899,6 +899,7 @@
}
/* Look-up the MM context based on old RA-ID and TLLI */
+ mmctx = sgsn_mm_ctx_by_tlli(msgb_tlli(msg), &old_ra_id);
if (!mmctx || mmctx->mm_state == GMM_DEREGISTERED) {
/* The MS has to perform GPRS attach */
DEBUGPC(DMM, " REJECT\n");