diff options
authorJacob Erlbeck <>2016-01-04 18:43:36 +0100
committerHolger Hans Peter Freyther <>2016-02-22 10:52:08 +0100
commitd35957a7d976e49dc3ff7eda0280f4fadbb69c0b (patch)
parentd58c033305a644b5c44a836ce8bc7a552499014d (diff)
sgsn: Change handling of missing mmctx in gsm48_rx_gmm_ra_upd_req
Currently the MM context is just overwritten by a call to sgsn_mm_ctx_by_tlli(msgb_tlli(msg), &old_ra_id) even if it has already been found by using the BSSGP info. With the changes made to sgsn_mm_ctx_by_tlli this will never find a MM context if the routing area has changed. If the routing area has not changed, the mmctx has already been found if it exists. This commit splits searching for an MM context (if it hasn't been found already) from checking, whether a found one can really be used. The actual search is removed, so that the MS will be forced to restart the attach procedure, which is less efficient but safe. Sponsored-by: On-Waves ehf
1 files changed, 15 insertions, 3 deletions
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index 7d3e3de75..5aea76f88 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -1164,9 +1164,21 @@ static int gsm48_rx_gmm_ra_upd_req(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
- /* 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) {
+ if (!mmctx) {
+ /* BSSGP doesn't give us an mmctx */
+ /* TODO: Check if there is an MM CTX with old_ra_id and
+ * the P-TMSI (if given, reguired for UMTS) or as last resort
+ * if the TLLI matches foreign_tlli (P-TMSI). Note that this
+ * is an optimization to avoid the RA reject (impl detached)
+ * below, which will cause a new attach cycle. */
+ }
+ if (!mmctx || !gprs_ra_id_equals(&mmctx->ra, &old_ra_id) ||
+ mmctx->mm_state == GMM_DEREGISTERED)
+ {
+ /* We cannot use the mmctx */
/* send a XID reset to re-set all LLC sequence numbers
* in the MS */