gbproxy: Refactor local message generation
This patch adds und uses the function gbproxy_gsm48_to_peer() which
takes a GSM 04.08 message, encapsulates it in BSSGP and LLC, and
sends it to the BSS peer. This function increments vu_gen_tx_bss
which is now used instead of imsi_acq_retries to set the N(U) of the
outgoing message.
Since imsi_acq_retries isn't currently incremented before a Detach
Accept is generated, this patch also fixes the N(U) of such messages.
Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 867364d..3257f74 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -286,10 +286,8 @@
if (!link_info)
return 0;
- if (link_info->imsi_acq_pending) {
+ if (link_info->imsi_acq_pending)
in_progress = 1;
- link_info->imsi_acq_retries += 1;
- }
gbproxy_link_info_discard_messages(link_info);
link_info->imsi_acq_pending = 0;
@@ -300,7 +298,7 @@
static void gbproxy_reset_imsi_acquisition(struct gbproxy_link_info* link_info)
{
gbproxy_restart_imsi_acquisition(link_info);
- link_info->imsi_acq_retries = 0;
+ link_info->vu_gen_tx_bss = GBPROXY_INIT_VU_GEN_TX;
}
static void gbproxy_flush_stored_messages(struct gbproxy_peer *peer,
@@ -351,6 +349,26 @@
}
}
+static int gbproxy_gsm48_to_peer(struct gbproxy_peer *peer,
+ struct gbproxy_link_info* link_info,
+ uint16_t bvci,
+ struct msgb *msg /* Takes msg ownership */)
+{
+ int rc;
+
+ /* Workaround to avoid N(U) collisions and to enable a restart
+ * of the IMSI acquisition procedure. This will work unless the
+ * SGSN has an initial V(UT) within [256-32, 256+n_retries]
+ * (see GSM 04.64, 8.4.2). */
+ gprs_push_llc_ui(msg, 0, GPRS_SAPI_GMM, link_info->vu_gen_tx_bss);
+ link_info->vu_gen_tx_bss = (link_info->vu_gen_tx_bss + 1) % 512;
+
+ gprs_push_bssgp_dl_unitdata(msg, link_info->tlli.current);
+ rc = gbprox_relay2peer(msg, peer, bvci);
+ msgb_free(msg);
+ return rc;
+}
+
static void gbproxy_acquire_imsi(struct gbproxy_peer *peer,
struct gbproxy_link_info* link_info,
uint16_t bvci)
@@ -360,18 +378,7 @@
/* Send IDENT REQ */
idreq_msg = gsm48_msgb_alloc();
gprs_put_identity_req(idreq_msg, GSM_MI_TYPE_IMSI);
- /* Workaround to avoid N(U) collisions and to enable a restart
- * of the IMSI acquisition procedure. This will work unless the
- * SGSN has an initial V(UT) within [256-32, 256+n_retries]
- * (see GSM 04.64, 8.4.2).
- * TODO: Check whether it is sensible to rely on this, it might
- * be an issue when P-TMSI patching is _not_ enabled and the SGSN
- * doesn't reset V(UT) after a detach. */
- gprs_push_llc_ui(idreq_msg, 0, GPRS_SAPI_GMM,
- (link_info->imsi_acq_retries + 256) % 512);
- gprs_push_bssgp_dl_unitdata(idreq_msg, link_info->tlli.current);
- gbprox_relay2peer(idreq_msg, peer, bvci);
- msgb_free(idreq_msg);
+ gbproxy_gsm48_to_peer(peer, link_info, bvci, idreq_msg);
}
static void gbproxy_tx_detach_acc(struct gbproxy_peer *peer,
@@ -383,11 +390,7 @@
/* 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,
- (link_info->imsi_acq_retries + 256) % 512);
- gprs_push_bssgp_dl_unitdata(detacc_msg, link_info->tlli.current);
- gbprox_relay2peer(detacc_msg, peer, bvci);
- msgb_free(detacc_msg);
+ gbproxy_gsm48_to_peer(peer, link_info, bvci, detacc_msg);
}
/* Return != 0 iff msg still needs to be processed */
diff --git a/openbsc/src/gprs/gb_proxy_tlli.c b/openbsc/src/gprs/gb_proxy_tlli.c
index fae05ed..093d2b3 100644
--- a/openbsc/src/gprs/gb_proxy_tlli.c
+++ b/openbsc/src/gprs/gb_proxy_tlli.c
@@ -238,6 +238,8 @@
link_info->tlli.ptmsi = GSM_RESERVED_TMSI;
link_info->sgsn_tlli.ptmsi = GSM_RESERVED_TMSI;
+ link_info->vu_gen_tx_bss = GBPROXY_INIT_VU_GEN_TX;
+
INIT_LLIST_HEAD(&link_info->stored_msgs);
return link_info;