gbproxy: Parse Detach Request messages
GSM 24.008 also allows a P-TMSI field in Detach request messages.
This patch adds gbprox_parse_gmm_detach_req() to parse Detach Request
messages which sets the ptmsi field if the IE is present.
In addition, when power_off is set to 1 (MO only), the
invalidate_tlli field is set, since Detach Request message is
expected in this case.
The second detach test (see 'RA update') is modified to use
power_off instead of relying on a Detach Accept from the network.
To make this work, the PTMSI of the RA Update Accept is fixed to
match the TLLI of the Detach Request.
Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 64fb55b..dd7dead 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -959,6 +959,43 @@
return 1;
}
+static int gbprox_parse_gmm_detach_req(uint8_t *data, size_t data_len,
+ struct gbproxy_parse_context *parse_ctx)
+{
+ uint8_t *value;
+ size_t value_len;
+ int detach_type;
+ int power_off;
+
+ parse_ctx->llc_msg_name = "DETACH_REQ";
+
+ /* Skip spare half octet */
+ /* Get Detach type */
+ if (v_fixed_shift(&data, &data_len, 1, &value) <= 0)
+ /* invalid */
+ return 0;
+
+ detach_type = *value & 0x07;
+ power_off = *value & 0x08 ? 1 : 0;
+
+ if (!parse_ctx->to_bss) {
+ /* Mobile originated */
+
+ if (power_off)
+ parse_ctx->invalidate_tlli = 1;
+
+ /* Get P-TMSI (Mobile identity), see GSM 24.008, 9.4.5.2 */
+ if (tlv_match(&data, &data_len,
+ GSM48_IE_GMM_ALLOC_PTMSI, &value, &value_len) > 0)
+ {
+ if (is_mi_tmsi(value, value_len))
+ parse_ctx->ptmsi_enc = value;
+ }
+ }
+
+ return 1;
+}
+
static int gbprox_parse_gmm_ra_upd_req(uint8_t *data, size_t data_len,
struct gbproxy_parse_context *parse_ctx)
{
@@ -1157,12 +1194,9 @@
case GSM48_MT_GMM_ID_RESP:
return gbprox_parse_gmm_id_resp(data, data_len, parse_ctx);
- break;
case GSM48_MT_GMM_DETACH_REQ:
- /* TODO: Check power off if !to_bss, if yes invalidate */
- parse_ctx->llc_msg_name = "DETACH_REQ";
- break;
+ return gbprox_parse_gmm_detach_req(data, data_len, parse_ctx);
case GSM48_MT_GMM_DETACH_ACK:
parse_ctx->llc_msg_name = "DETACH_ACK";
@@ -1331,6 +1365,11 @@
sep, mi_buf);
sep = ",";
}
+ if (parse_ctx->invalidate_tlli) {
+ LOGP(DGPRS, LOGL_DEBUG, "%s invalidate", sep);
+ sep = ",";
+ }
+
LOGP(DGPRS, LOGL_DEBUG, "\n");
}