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USSD: fix routing to multiple MSC 

hlr_ussd.c so far hardcoded osmo-msc's default IPA-name and hence was
only able to negotiate USSD sessions to
- a single osmo-msc
- that has no custom IPA-name set.
Fix: correctly route USSD to any number of MSC with any custom IPA
names.

Resolve the right MSC's IPA name from the USSD session's IMSI, using
hlr_subscriber->vlr_number to determine the right GSUP peer. Cache it in
ss_session->vlr_number to have at most one db hit for routing per
session.

Related: OS#3710
Change-Id: I18067bfadd33a6bc59a9ee336b6937313826fce3
This commit is contained in:
Neels Hofmeyr 2019-04-02 04:26:55 +02:00 committed by Oliver Smith
parent f7d3251d9a
commit f1fe94c8ca
1 changed files with 33 additions and 4 deletions
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37
src/hlr_ussd.c
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@ -34,6 +34,7 @@
#include "gsup_server.h"
#include "gsup_router.h"
#include "logging.h"
#include "db.h"
/***********************************************************************
* core data structures expressing config from VTY
@ -166,6 +167,9 @@ struct ss_session {
const struct hlr_iuse *iuse;
} u;
/* subscriber's vlr_number, will be looked up once per session and cached here */
char vlr_number[32];
/* we don't keep a pointer to the osmo_gsup_{route,conn} towards the MSC/VLR here,
* as this might change during inter-VLR hand-over, and we simply look-up the serving MSC/VLR
* every time we receive an USSD component from the EUSE */
@ -222,6 +226,33 @@ struct ss_session *ss_session_alloc(struct hlr *hlr, const char *imsi, uint32_t
* handling functions for encoding SS messages + wrapping them in GSUP
***********************************************************************/
/* Resolve the target MSC by ss->imsi and send GSUP message. */
static int ss_gsup_send(struct ss_session *ss, struct osmo_gsup_server *gs, struct msgb *msg)
{
struct hlr_subscriber subscr = {};
int rc;
/* Use vlr_number as looked up by the caller, or look up now. */
if (!ss->vlr_number[0]) {
rc = db_subscr_get_by_imsi(g_hlr->dbc, ss->imsi, &subscr);
if (rc < 0) {
LOGPSS(ss, LOGL_ERROR, "Cannot find subscriber, cannot route GSUP message\n");
msgb_free(msg);
return -EINVAL;
}
osmo_strlcpy(ss->vlr_number, subscr.vlr_number, sizeof(ss->vlr_number));
}
if (!ss->vlr_number[0]) {
LOGPSS(ss, LOGL_ERROR, "Cannot send GSUP message, no VLR number stored for subscriber\n");
msgb_free(msg);
return -EINVAL;
}
LOGPSS(ss, LOGL_DEBUG, "Tx SS/USSD to VLR '%s'\n", ss->vlr_number);
return osmo_gsup_addr_send(gs, (uint8_t *)ss->vlr_number, strlen(ss->vlr_number) + 1, msg);
}
static int ss_tx_to_ms(struct ss_session *ss, enum osmo_gsup_message_type gsup_msg_type,
bool final, struct msgb *ss_msg)
@ -246,8 +277,7 @@ static int ss_tx_to_ms(struct ss_session *ss, enum osmo_gsup_message_type gsup_m
osmo_gsup_encode(resp_msg, &resp);
msgb_free(ss_msg);
/* FIXME: resolve this based on the database vlr_addr */
return osmo_gsup_addr_send(g_hlr->gs, (uint8_t *)"MSC-00-00-00-00-00-00", 22, resp_msg);
return ss_gsup_send(ss, g_hlr->gs, resp_msg);
}
#if 0
@ -433,8 +463,7 @@ static int handle_ussd(struct osmo_gsup_conn *conn, struct ss_session *ss,
OSMO_ASSERT(msg_out);
/* Received from EUSE, Forward to VLR */
osmo_gsup_encode(msg_out, gsup);
/* FIXME: resolve this based on the database vlr_addr */
osmo_gsup_addr_send(conn->server, (uint8_t *)"MSC-00-00-00-00-00-00", 22, msg_out);
ss_gsup_send(ss, conn->server, msg_out);
} else {
/* Received from VLR (MS) */
if (ss->is_external) {