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gb_proxy: add support for relaying BSSGP RIM messages 

BSSGP RIM messages are routed from a source to a destination cell by a
RIM routing information IE. Add parsing for the routing information and
support for relaying RIM messages to the destination cell/PCU. If the
destination cell/PCU is not directly connected to osmo-gbproxy route the
rim message to the first connected SGSN.

Change-Id: Idd1ea46832e044f0ade15af32250f90517d848d8
Related: SYS#5103
This commit is contained in:
Philipp Maier 2021-02-09 17:03:03 +01:00 committed by laforge
parent 3ea379395f
commit 1c5766b0ec
1 changed files with 128 additions and 5 deletions
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133
src/gb_proxy.c
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@ -46,6 +46,7 @@
#include <osmocom/gprs/gprs_bssgp2.h>
#include <osmocom/gprs/gprs_bssgp_bss.h>
#include <osmocom/gprs/bssgp_bvc_fsm.h>
#include <osmocom/gprs/protocol/gsm_08_18.h>
#include <osmocom/gsm/gsm23236.h>
#include <osmocom/gsm/gsm_utils.h>
@ -886,6 +887,79 @@ static int rx_bvc_reset_from_bss(struct gbproxy_nse *nse, struct msgb *msg, stru
return 0;
}
/* Receive an incoming RIM message from a BSS-side NS-VC */
static int gbprox_rx_rim_from_bss(struct tlv_parsed *tp, struct gbproxy_nse *nse, struct msgb *msg, char *log_pfx,
const char *pdut_name)
{
struct gbproxy_sgsn *sgsn;
struct gbproxy_cell *dest_cell;
struct gbproxy_cell *src_cell;
struct bssgp_rim_routing_info dest_ri;
struct bssgp_rim_routing_info src_ri;
int rc;
rc = bssgp_parse_rim_ri(&dest_ri, TLVP_VAL(&tp[0], BSSGP_IE_RIM_ROUTING_INFO),
TLVP_LEN(&tp[0], BSSGP_IE_RIM_ROUTING_INFO));
if (rc < 0) {
LOGP(DGPRS, LOGL_ERROR, "%s %s cannot parse destination RIM routing info\n", log_pfx, pdut_name);
return bssgp_tx_status(BSSGP_CAUSE_INV_MAND_INF, NULL, msg);
}
rc = bssgp_parse_rim_ri(&src_ri, TLVP_VAL(&tp[1], BSSGP_IE_RIM_ROUTING_INFO),
TLVP_LEN(&tp[1], BSSGP_IE_RIM_ROUTING_INFO));
if (rc < 0) {
LOGP(DGPRS, LOGL_ERROR, "%s %s cannot parse source RIM routing info\n", log_pfx, pdut_name);
return bssgp_tx_status(BSSGP_CAUSE_INV_MAND_INF, NULL, msg);
}
/* Since gbproxy is 2G only we do not expect to get RIM messages only from GERAN cells. */
if (src_ri.discr != BSSGP_RIM_ROUTING_INFO_GERAN) {
LOGP(DGPRS, LOGL_ERROR, "%s %s source RIM routing info is not GERAN (%s)\n", log_pfx, pdut_name,
bssgp_rim_ri_name(&src_ri));
return bssgp_tx_status(BSSGP_CAUSE_UNKN_RIM_AI, NULL, msg);
}
/* Lookup source cell to make sure that the source RIM routing information actually belongs
* to a valid cell that we know */
src_cell = gbproxy_cell_by_cellid(nse->cfg, &src_ri.geran.raid, src_ri.geran.cid);
if (!src_cell) {
LOGP(DGPRS, LOGL_NOTICE, "%s %s cannot find cell for source RIM routing info (%s)\n", log_pfx,
pdut_name, bssgp_rim_ri_name(&src_ri));
return bssgp_tx_status(BSSGP_CAUSE_UNKN_RIM_AI, NULL, msg);
}
/* TODO: Use bssgp_bvc_get_features_negotiated(src_cell->bss_bvc->fi) to check if the the BSS sided BVC actually
* did negotiate RIM support. If not we should respond with a BSSGP STATUS message. The cause code should be
* BSSGP_CAUSE_PDU_INCOMP_FEAT. */
/* If Destination is known by gbproxy, route directly */
if (dest_ri.discr == BSSGP_RIM_ROUTING_INFO_GERAN) {
dest_cell = gbproxy_cell_by_cellid(nse->cfg, &dest_ri.geran.raid, dest_ri.geran.cid);
if (dest_cell) {
/* TODO: Also check if dest_cell->bss_bvc is RIM-capable (see also above). If not we should
* respond with a BSSGP STATUS message as well because it also would make no sense to try
* routing the RIM message to the next RIM-capable SGSN. */
LOGP(DLBSSGP, LOGL_DEBUG, "%s %s relaying to peer (nsei=%u) RIM-PDU: src=%s, dest=%s\n", log_pfx, pdut_name,
dest_cell->bss_bvc->nse->nsei, bssgp_rim_ri_name(&src_ri), bssgp_rim_ri_name(&dest_ri));
return gbprox_relay2peer(msg, dest_cell->bss_bvc, 0);
}
}
/* Otherwise pass on to a RIM-capable SGSN */
/* TODO: We need to extend gbproxy_select_sgsn() so that it selects a RIM-capable SGSN, at the moment we just
* get any SGSN and just assume that it is RIM-capable. */
sgsn = gbproxy_select_sgsn(nse->cfg, NULL);
if (!sgsn) {
LOGP(DGPRS, LOGL_NOTICE,
"%s %s cannot route RIM message (%s to %s) since no RIM capable SGSN is found!\n", log_pfx,
pdut_name, bssgp_rim_ri_name(&src_ri), bssgp_rim_ri_name(&dest_ri));
return bssgp_tx_status(BSSGP_CAUSE_UNKN_RIM_AI, NULL, msg);
}
LOGP(DLBSSGP, LOGL_DEBUG, "%s %s relaying to SGSN(%05u/%s) RIM-PDU: src=%s, dest=%s\n", log_pfx, pdut_name,
sgsn->nse->nsei, sgsn->name, bssgp_rim_ri_name(&src_ri), bssgp_rim_ri_name(&dest_ri));
return gbprox_relay2nse(msg, sgsn->nse, 0);
}
/* Receive an incoming signalling message from a BSS-side NS-VC */
static int gbprox_rx_sig_from_bss(struct gbproxy_nse *nse, struct msgb *msg, uint16_t ns_bvci)
{
@ -984,8 +1058,7 @@ static int gbprox_rx_sig_from_bss(struct gbproxy_nse *nse, struct msgb *msg, uin
case BSSGP_PDUT_RAN_INFO_ACK:
case BSSGP_PDUT_RAN_INFO_ERROR:
case BSSGP_PDUT_RAN_INFO_APP_ERROR:
/* FIXME: route based in RIM Routing IE */
rc = bssgp_tx_status(BSSGP_CAUSE_PDU_INCOMP_FEAT, NULL, msg);
rc = gbprox_rx_rim_from_bss(tp, nse, msg, log_pfx, pdut_name);
break;
case BSSGP_PDUT_LLC_DISCARD:
case BSSGP_PDUT_FLUSH_LL_ACK:
@ -1134,6 +1207,58 @@ static int rx_bvc_reset_from_sgsn(struct gbproxy_nse *nse, struct msgb *msg, str
return 0;
}
/* Receive an incoming RIM message from the SGSN-side NS-VC */
static int gbprox_rx_rim_from_sgsn(struct tlv_parsed *tp, struct gbproxy_nse *nse, struct msgb *msg, char *log_pfx,
const char *pdut_name)
{
struct gbproxy_sgsn *sgsn;
struct gbproxy_cell *dest_cell;
struct bssgp_rim_routing_info dest_ri;
struct bssgp_rim_routing_info src_ri;
int rc;
/* TODO: Reply with STATUS if BSSGP didn't negotiate RIM feature, see also comments in
gbprox_rx_rim_from_bss() */
rc = bssgp_parse_rim_ri(&dest_ri, TLVP_VAL(&tp[0], BSSGP_IE_RIM_ROUTING_INFO),
TLVP_LEN(&tp[0], BSSGP_IE_RIM_ROUTING_INFO));
if (rc < 0) {
LOGP(DGPRS, LOGL_ERROR, "%s %s cannot parse destination RIM routing info\n", log_pfx, pdut_name);
return bssgp_tx_status(BSSGP_CAUSE_INV_MAND_INF, NULL, msg);
}
rc = bssgp_parse_rim_ri(&src_ri, TLVP_VAL(&tp[1], BSSGP_IE_RIM_ROUTING_INFO),
TLVP_LEN(&tp[1], BSSGP_IE_RIM_ROUTING_INFO));
if (rc < 0) {
LOGP(DGPRS, LOGL_ERROR, "%s %s cannot parse source RIM routing info\n", log_pfx, pdut_name);
return bssgp_tx_status(BSSGP_CAUSE_INV_MAND_INF, NULL, msg);
}
/* Since gbproxy is 2G only we do not expect to get RIM messages that target non-GERAN cells. */
if (dest_ri.discr != BSSGP_RIM_ROUTING_INFO_GERAN) {
LOGP(DGPRS, LOGL_ERROR, "%s %s destination RIM routing info is not GERAN (%s)\n", log_pfx, pdut_name,
bssgp_rim_ri_name(&dest_ri));
return bssgp_tx_status(BSSGP_CAUSE_UNKN_RIM_AI, NULL, msg);
}
/* Lookup destination cell */
dest_cell = gbproxy_cell_by_cellid(nse->cfg, &dest_ri.geran.raid, dest_ri.geran.cid);
if (!dest_cell) {
LOGP(DGPRS, LOGL_NOTICE, "%s %s cannot find cell for destination RIM routing info (%s)\n", log_pfx,
pdut_name, bssgp_rim_ri_name(&dest_ri));
return bssgp_tx_status(BSSGP_CAUSE_UNKN_RIM_AI, NULL, msg);
}
/* TODO: Check if the BVC of the destination cell actually did negotiate RIM support, see also comments
* in gbprox_rx_rim_from_bss() */
sgsn = gbproxy_sgsn_by_nsei(nse->cfg, nse->nsei);
OSMO_ASSERT(sgsn);
LOGP(DLBSSGP, LOGL_DEBUG, "%s %s relaying from SGSN(%05u/%s) RIM-PDU: src=%s, dest=%s\n", log_pfx, pdut_name,
sgsn->nse->nsei, sgsn->name, bssgp_rim_ri_name(&src_ri), bssgp_rim_ri_name(&dest_ri));
return gbprox_relay2peer(msg, dest_cell->bss_bvc, 0);
}
/* Receive an incoming signalling message from the SGSN-side NS-VC */
static int gbprox_rx_sig_from_sgsn(struct gbproxy_nse *nse, struct msgb *msg, uint16_t ns_bvci)
{
@ -1286,9 +1411,7 @@ static int gbprox_rx_sig_from_sgsn(struct gbproxy_nse *nse, struct msgb *msg, ui
case BSSGP_PDUT_RAN_INFO_ACK:
case BSSGP_PDUT_RAN_INFO_ERROR:
case BSSGP_PDUT_RAN_INFO_APP_ERROR:
/* FIXME: route based in RIM Routing IE */
rc = bssgp_tx_status(BSSGP_CAUSE_PDU_INCOMP_FEAT, NULL, msg);
break;
rc = gbprox_rx_rim_from_sgsn(tp, nse, msg, log_pfx, pdut_name);
default:
LOGPNSE(nse, LOGL_NOTICE, "Rx %s: Not supported\n", pdut_name);
rate_ctr_inc(&cfg->ctrg->ctr[GBPROX_GLOB_CTR_PROTO_ERR_SGSN]);