fixeria has submitted this change. (
https://gerrit.osmocom.org/c/osmo-hlr/+/33528 )
Change subject: USSD: fix handling of ussd-DataCodingScheme != 0x0f
......................................................................
USSD: fix handling of ussd-DataCodingScheme != 0x0f
The usual Data Coding Scheme value in the mobile-originated USSD
request (processUnstructuredSS-Request) is 0x0f, which means:
0000 .... = Coding Group: Coding Group 0 (Language using the GSM 7 bit
default alphabet)
.... 1111 = Language: unspecified
However some modems are known to use a different default value, if
not specified explicitly (AT+CUSD has optional DCS parameter):
0000 .... = Coding Group: Coding Group 0 (Language using the GSM 7 bit
default alphabet)
.... 0000 = Language: German (0)
In function rx_proc_ss_req(), we should not be using req.ussd_text,
because this field has been deprecated and may contain unexpected
data. For example, in the abovementioned case it would contain the
7 bit encoded ussd-String 'aa510c061b01'O and osmo-hlr would indeed
fail to find a matching route for a non-ASCII string.
Instead of relaying on gsm0480_parse_facility_ie(), let's check the
Data Coding Scheme value and decode the request string ourselves.
Expect the Coding Group 0, but be more tolerant to the indicated
language: print a warning and treat it as '1111'B (unspecified).
Change-Id: Ib7bac660b1a7942adcfbe7b14f162c95061a25db
Related: OS#6075
---
M src/hlr_ussd.c
1 file changed, 66 insertions(+), 2 deletions(-)
Approvals:
laforge: Looks good to me, approved
neels: Looks good to me, but someone else must approve
osmith: Looks good to me, but someone else must approve
Jenkins Builder: Verified
diff --git a/src/hlr_ussd.c b/src/hlr_ussd.c
index 8d5237f..1c0107b 100644
--- a/src/hlr_ussd.c
+++ b/src/hlr_ussd.c
@@ -122,9 +122,40 @@
talloc_free(rt);
}
-static struct hlr_ussd_route *ussd_route_lookup_7bit(struct hlr *hlr, const
char *ussd_code)
+static struct hlr_ussd_route *ussd_route_lookup_for_req(struct hlr *hlr, const
struct ss_request *req)
{
+ const uint8_t cgroup = req->ussd_data_dcs >> 4;
+ const uint8_t lang = req->ussd_data_dcs & 0x0f;
+ char ussd_code[GSM0480_USSD_7BIT_STRING_LEN];
struct hlr_ussd_route *rt;
+
+ ussd_code[0] = '\0';
+
+ /* We support only the Coding Group 0 (GSM 7-bit default alphabeet).
In fact,
+ * the USSD request is usually limited to [*#0-9], so we don't really
need to
+ * support other coding groups and languages. */
+ switch (cgroup) {
+ case 0:
+ /* The Language is usually set to '1111'B (unspecified), but
some UEs
+ * are known to indicate '0000'B (German). */
+ if (lang != 0x0f) {
+ LOGP(DSS, LOGL_NOTICE, "USSD DataCodingScheme (0x%02x):
"
+ "the Language is usually set to 15 (unspecified), "
+ "but the request indicates %u - ignoring this\n",
+ req->ussd_data_dcs, lang);
+ /* do not abort, attempt to decode as if it was '1111'B
*/
+ }
+
+ gsm_7bit_decode_n_ussd(&ussd_code[0], sizeof(ussd_code),
+ req->ussd_data, (req->ussd_data_len * 8)
/ 7);
+ break;
+ default:
+ LOGP(DSS, LOGL_ERROR, "USSD DataCodingScheme (0x%02x): "
+ "Coding Group %u is not supported, expecting Coding Group
0\n",
+ req->ussd_data_dcs, cgroup);
+ return NULL;
+ }
+
llist_for_each_entry(rt, &hlr->ussd_routes, list) {
if (!strncmp(ussd_code, rt->prefix, strlen(rt->prefix))) {
LOGP(DSS, LOGL_DEBUG, "Found %s '%s' (prefix '%s') for
USSD "
@@ -603,7 +634,7 @@
} else {
/* VLR->EUSE: MO USSD. VLR is known ('conn'),
EUSE is to be resolved */
struct hlr_ussd_route *rt;
- rt = ussd_route_lookup_7bit(hlr, (const char *)
req.ussd_text);
+ rt = ussd_route_lookup_for_req(hlr, &req);
if (rt) {
if (rt->is_external) {
ss->is_external = true;
--
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Gerrit-Project: osmo-hlr
Gerrit-Branch: master
Gerrit-Change-Id: Ib7bac660b1a7942adcfbe7b14f162c95061a25db
Gerrit-Change-Number: 33528
Gerrit-PatchSet: 3
Gerrit-Owner: fixeria <[email protected]>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria <[email protected]>
Gerrit-Reviewer: laforge <[email protected]>
Gerrit-Reviewer: neels <[email protected]>
Gerrit-Reviewer: osmith <[email protected]>
Gerrit-Reviewer: pespin <[email protected]>
Gerrit-MessageType: merged
