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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
This commit is contained in:
Jacob Erlbeck 2014-09-22 15:41:21 +02:00 committed by Holger Hans Peter Freyther
parent d211d1d999
commit 657502812b
4 changed files with 33 additions and 25 deletions
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5
openbsc/include/openbsc/gb_proxy.h
View File

@ -10,6 +10,8 @@
#include <sys/types.h>
#include <regex.h>
#define GBPROXY_INIT_VU_GEN_TX 256
struct rate_ctr_group;
struct gprs_gb_parse_context;
struct tlv_parsed;
@ -148,11 +150,12 @@ struct gbproxy_link_info {
int imsi_acq_pending;
struct llist_head stored_msgs;
int imsi_acq_retries;
unsigned vu_gen_tx_bss;
int is_deregistered;
int imsi_matches;
};

45
openbsc/src/gprs/gb_proxy.c
View File

@ -286,10 +286,8 @@ static int gbproxy_restart_imsi_acquisition(struct gbproxy_link_info* link_info)
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 int gbproxy_restart_imsi_acquisition(struct gbproxy_link_info* link_info)
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 void gbproxy_flush_stored_messages(struct gbproxy_peer *peer,
}
}
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 @@ static void gbproxy_acquire_imsi(struct gbproxy_peer *peer,
/* 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 @@ static void gbproxy_tx_detach_acc(struct gbproxy_peer *peer,
/* 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 */

2
openbsc/src/gprs/gb_proxy_tlli.c
View File

@ -238,6 +238,8 @@ struct gbproxy_link_info *gbproxy_link_info_alloc( struct gbproxy_peer *peer)
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;

6
openbsc/tests/gbproxy/gbproxy_test.ok
View File

@ -3516,7 +3516,7 @@ CALLBACK, event 0, msg length 44, bvci 0x1002
NS UNITDATA MESSAGE to BSS, BVCI 0x1002, msg length 24 (gprs_ns_sendmsg)
MESSAGE to BSS at 0x01020304:1111, msg length 28
00 00 10 02 00 80 00 de ad 00 50 20 16 82 02 58 0e 00 09 41 c4 05 08 06 00 29 4a 68
00 00 10 02 00 80 00 de ad 00 50 20 16 82 02 58 0e 00 09 41 c4 09 08 06 00 da 80 ca
result (DETACH REQ) = 0
@ -3582,7 +3582,7 @@ CALLBACK, event 0, msg length 44, bvci 0x1002
NS UNITDATA MESSAGE to BSS, BVCI 0x1002, msg length 24 (gprs_ns_sendmsg)
MESSAGE to BSS at 0x01020304:1111, msg length 28
00 00 10 02 00 80 00 de ad 00 50 20 16 82 02 58 0e 00 09 41 c4 05 08 06 00 29 4a 68
00 00 10 02 00 80 00 de ad 00 50 20 16 82 02 58 0e 00 09 41 c4 09 08 06 00 da 80 ca
result (DETACH REQ) = 0
@ -5515,7 +5515,7 @@ CALLBACK, event 0, msg length 44, bvci 0x1002
NS UNITDATA MESSAGE to BSS, BVCI 0x1002, msg length 24 (gprs_ns_sendmsg)
MESSAGE to BSS at 0x01020304:1111, msg length 28
00 00 10 02 00 af e2 b7 00 00 50 20 16 82 02 58 0e 00 09 41 c4 01 08 06 00 11 f5 c0
00 00 10 02 00 af e2 b7 00 00 50 20 16 82 02 58 0e 00 09 41 c4 05 08 06 00 29 4a 68
result (DETACH REQ (MO)) = 0