sgsn: Do not die in _bssgp_tx_dl_ud on TLLI mismatch (TODO)

Currently an OSMO_ASSERT fails, if the message's and the mmctx's
TLLIs do not match.

This commit turns the assertion into an ERROR log message and uses
the default values for IMSI, DRX, and RA CAP instead of the MM
context values in this case.

TODO:
  - find the real source for the problem
  - add test cases derived from what is being described in the ticket

Ticket: OW#1322
Sponsored-by: On-Waves ehf

1 files changed, 20 insertions, 9 deletions

diff --git a/openbsc/src/gprs/gprs_llc.c b/openbsc/src/gprs/gprs_llc.c
index 936354a09..6259eb58e 100644
--- a/openbsc/src/gprs/gprs_llc.c
+++ b/openbsc/src/gprs/gprs_llc.c
@@ -65,16 +65,27 @@ static int _bssgp_tx_dl_ud(struct msgb *msg, struct sgsn_mm_ctx *mmctx)
 	 * not yet have a MMC context (e.g. XID negotiation of primarly
 	 * LLC connection fro GMM sapi). */
 	if (mmctx) {
-		dup.imsi = mmctx->imsi;
-		dup.drx_parms = mmctx->drx_parms;
-		dup.ms_ra_cap.len = mmctx->ms_radio_access_capa.len;
-		dup.ms_ra_cap.v = mmctx->ms_radio_access_capa.buf;
-
 		/* make sure we only send it to the right llme */
-		OSMO_ASSERT(msgb_tlli(msg) == mmctx->llme->tlli
-				|| msgb_tlli(msg) == mmctx->llme->old_tlli
-				|| tlli_foreign2local(msgb_tlli(msg)) == mmctx->llme->tlli
-				|| tlli_foreign2local(msgb_tlli(msg)) == mmctx->llme->old_tlli);
+		if (msgb_tlli(msg) != mmctx->llme->tlli &&
+		    msgb_tlli(msg) != mmctx->llme->old_tlli &&
+		    tlli_foreign2local(msgb_tlli(msg)) != mmctx->llme->tlli &&
+		    tlli_foreign2local(msgb_tlli(msg)) != mmctx->llme->old_tlli)
+		{
+			LOGP(DLLC, LOGL_ERROR,
+			     "MM context TLLI mismatch when sending DL unitdata, "
+			     "msg TLLI = %08x, ctx TLLI = %08x, "
+			     "ctx old TLLI = %08x. "
+			     "Using default values for IMSI, DRX, RA CAP\n",
+			     msgb_tlli(msg),
+			     mmctx->llme->tlli,
+			     mmctx->llme->old_tlli);
+			osmo_log_backtrace(DLLC, LOGL_INFO);
+		} else {
+			dup.imsi = mmctx->imsi;
+			dup.drx_parms = mmctx->drx_parms;
+			dup.ms_ra_cap.len = mmctx->ms_radio_access_capa.len;
+			dup.ms_ra_cap.v = mmctx->ms_radio_access_capa.buf;
+		}
 	}
 	memcpy(&dup.qos_profile, qos_profile_default,
 		sizeof(qos_profile_default));