gbproxy: Send DETACH_ACC if the IMSI has not been acquired
If IMSI acquisition is enabled and the gbproxy receives a Detach
request from the MS, it cannot pass it to the SGSN since the
acquisition has not yet been completed.
This patch implements the generation of a Detach Accept message and
for this case and updates the TLLI state accordingly.
Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 344e164..ee80375 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -110,6 +110,17 @@
gh->data[0] = id_type;
}
+/* Transmit Chapter 9.4.6.2 Detach Accept (mobile originated detach) */
+static void gprs_put_mo_detach_acc(struct msgb *msg)
+{
+ struct gsm48_hdr *gh;
+
+ gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 1);
+ gh->proto_discr = GSM48_PDISC_MM_GPRS;
+ gh->msg_type = GSM48_MT_GMM_DETACH_ACK;
+ gh->data[0] = 0; /* no force to standby */
+}
+
static void gprs_push_llc_ui(struct msgb *msg,
int is_uplink, unsigned sapi, unsigned nu)
{
@@ -348,6 +359,21 @@
msgb_free(idreq_msg);
}
+static void gbproxy_tx_detach_acc(struct gbproxy_peer *peer,
+ struct gbproxy_tlli_info* tlli_info,
+ uint16_t bvci)
+{
+ struct msgb *detacc_msg;
+
+ /* Send DETACH ACC */
+ detacc_msg = gsm48_msgb_alloc();
+ gprs_put_mo_detach_acc(detacc_msg);
+ gprs_push_llc_ui(detacc_msg, 0, GPRS_SAPI_GMM,
+ (tlli_info->imsi_acq_retries + 256) % 512);
+ gprs_push_bssgp_dl_unitdata(detacc_msg, tlli_info->tlli.current);
+ gbprox_relay2peer(detacc_msg, peer, bvci);
+ msgb_free(detacc_msg);
+}
/* Return != 0 iff msg still needs to be processed */
static int gbproxy_imsi_acquisition(struct gbproxy_peer *peer,
@@ -365,16 +391,38 @@
if (!tlli_info->imsi_acq_pending && tlli_info->imsi_len > 0)
return 1;
- if (parse_ctx->g48_hdr &&
- parse_ctx->g48_hdr->msg_type == GSM48_MT_GMM_ATTACH_REQ)
- {
- if (gbproxy_restart_imsi_acquisition(tlli_info)) {
- LOGP(DLLC, LOGL_INFO,
- "NSEI=%d(BSS) IMSI acquisition was in progress "
- "when receiving an ATTACH_REQ.\n",
- msgb_nsei(msg));
+ if (parse_ctx->g48_hdr)
+ switch (parse_ctx->g48_hdr->msg_type)
+ {
+ case GSM48_MT_GMM_ATTACH_REQ:
+ if (gbproxy_restart_imsi_acquisition(tlli_info)) {
+ LOGP(DLLC, LOGL_INFO,
+ "NSEI=%d(BSS) IMSI acquisition was in progress "
+ "when receiving an ATTACH_REQ.\n",
+ msgb_nsei(msg));
+ }
+ break;
+ case GSM48_MT_GMM_DETACH_REQ:
+ /* Nothing has been sent to the SGSN yet */
+ if (tlli_info->imsi_acq_pending) {
+ LOGP(DLLC, LOGL_INFO,
+ "NSEI=%d(BSS) IMSI acquisition was in progress "
+ "when receiving a DETACH_REQ.\n",
+ msgb_nsei(msg));
+ }
+ if (!parse_ctx->invalidate_tlli) {
+ LOGP(DLLC, LOGL_INFO,
+ "NSEI=%d(BSS) IMSI not yet acquired, "
+ "faking a DETACH_ACC.\n",
+ msgb_nsei(msg));
+ gbproxy_tx_detach_acc(peer, tlli_info, msgb_bvci(msg));
+ parse_ctx->invalidate_tlli = 1;
+ }
+ gbproxy_reset_imsi_acquisition(tlli_info);
+ gbproxy_update_tlli_state_after(peer, tlli_info, now,
+ parse_ctx);
+ return 0;
}
- }
if (tlli_info->imsi_acq_pending && tlli_info->imsi_len > 0) {
int is_ident_resp =