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gsm/gsm0480: refactor and expose gsm0480_parse_facility_ie() 

This function can be used when there is only a part of GSM 04.80
message available - Facility IE, e.g. when a message is carried
over GSUP/MAP. Let's expose it.

Refactoring includes the following:

  - adding the 'gsm0480_' prefix;
  - correcting inverted return value;
  - cosmetic code style changes.

Change-Id: I623c39ffbe6cdee65eade8435a2faa04d0da193e
This commit is contained in:
Vadim Yanitskiy 2018-06-11 04:58:53 +07:00
parent 52e44121db
commit 5a09f75c1e
5 changed files with 81 additions and 16 deletions
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2
include/osmocom/gsm/gsm0480.h
View File

@ -93,6 +93,8 @@ struct ss_request {
int gsm0480_extract_ie_by_tag(const struct gsm48_hdr *hdr, uint16_t msg_len,
uint8_t **ie, uint16_t *ie_len, uint8_t ie_tag);
int gsm0480_parse_facility_ie(const uint8_t *facility_ie, uint16_t length,
struct ss_request *req);
int gsm0480_decode_ss_request(const struct gsm48_hdr *hdr, uint16_t len,
struct ss_request *request);

46
src/gsm/gsm0480.c
View File

@ -201,8 +201,6 @@ static int parse_ss_facility(const uint8_t *ss_facility, uint16_t len,
struct ss_request *req);
static int parse_ss_info_elements(const uint8_t *ss_ie, uint16_t len,
struct ss_request *req);
static int parse_facility_ie(const uint8_t *facility_ie, uint16_t length,
struct ss_request *req);
static int parse_ss_invoke(const uint8_t *invoke_data, uint16_t length,
struct ss_request *req);
static int parse_ss_return_result(const uint8_t *rr_data, uint16_t length,
@ -419,7 +417,7 @@ static int parse_ss_facility(const uint8_t *ss_facility, uint16_t len,
if (len - 1 < facility_length)
return 0;
return parse_facility_ie(ss_facility + 1, facility_length, req);
return !gsm0480_parse_facility_ie(ss_facility + 1, facility_length, req);
}
static int parse_ss_info_elements(const uint8_t *ss_ie, uint16_t len,
@ -445,7 +443,7 @@ static int parse_ss_info_elements(const uint8_t *ss_ie, uint16_t len,
case GSM48_IE_CAUSE:
break;
case GSM0480_IE_FACILITY:
rc = parse_facility_ie(ss_ie + 2, iei_length, req);
rc = !gsm0480_parse_facility_ie(ss_ie + 2, iei_length, req);
break;
case GSM0480_IE_SS_VERSION:
break;
@ -464,31 +462,40 @@ static int parse_ss_info_elements(const uint8_t *ss_ie, uint16_t len,
return rc;
}
static int parse_facility_ie(const uint8_t *facility_ie, uint16_t length,
struct ss_request *req)
/*! Parse the components of a given Facility IE
* \param[in] facility_ie The Facility IE
* \param[in] length The length of Facility IE
* \param[out] req Abstract representation of SS message
* \return 0 in case of success, otherwise -ERRNO
*/
int gsm0480_parse_facility_ie(const uint8_t *facility_ie, uint16_t length,
struct ss_request *req)
{
int rc = 1;
uint8_t component_length;
uint8_t component_type;
uint8_t offset = 0;
int rc = 1;
/* Iterate over components within IE */
while (offset + 2 <= length) {
/* Component Type tag - table 3.7 */
uint8_t component_type = facility_ie[offset];
uint8_t component_length = facility_ie[offset+1];
component_type = facility_ie[offset];
component_length = facility_ie[offset + 1];
/* size check */
/* Make sure that there is no overflow */
if (offset + 2 + component_length > length) {
LOGP(0, LOGL_ERROR, "Component does not fit.\n");
return 0;
return -EINVAL;
}
switch (component_type) {
case GSM0480_CTYPE_INVOKE:
rc &= parse_ss_invoke(facility_ie+2,
rc &= parse_ss_invoke(facility_ie + 2,
component_length,
req);
break;
case GSM0480_CTYPE_RETURN_RESULT:
rc &= parse_ss_return_result(facility_ie+2,
rc &= parse_ss_return_result(facility_ie + 2,
component_length,
req);
break;
@ -502,10 +509,17 @@ static int parse_facility_ie(const uint8_t *facility_ie, uint16_t length,
rc = 0;
break;
}
offset += (component_length+2);
};
return rc;
offset += (component_length + 2);
}
/**
* The internal functions are using inverted return
* codes, where '0' means error/failure. While a
* common approach is to return negative errno in
* case of any failure, and '0' if all is ok.
*/
return (rc == 0) ? -EINVAL : 0;
}
/* Parse an Invoke component - see table 3.3 */

1
src/gsm/libosmogsm.map
View File

@ -90,6 +90,7 @@ gsm0480_create_ussd_resp;
gsm0480_create_ussd_notify;
gsm0480_create_ussd_release_complete;
gsm0480_extract_ie_by_tag;
gsm0480_parse_facility_ie;
gsm0480_decode_ussd_request;
gsm0480_decode_ss_request;
gsm0480_wrap_facility;

40
tests/ussd/ussd_test.c
View File

@ -188,6 +188,43 @@ static void test_extract_ie_by_tag(void)
printf("\n");
}
static void test_parse_facility_ie(void)
{
struct ss_request req;
uint16_t ie_len;
uint8_t *ie;
int rc;
printf("[i] Testing gsm0480_parse_facility_ie()\n");
/* Extract Facility IE from FACILITY message */
rc = gsm0480_extract_ie_by_tag((struct gsm48_hdr *) ussd_facility,
sizeof(ussd_facility), &ie, &ie_len, GSM0480_IE_FACILITY);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(ie != NULL && ie_len > 0);
printf("[?] FACILITY message with Facility IE "
"(len=%u): %s\n", ie_len, osmo_hexdump(ie, ie_len));
/* Attempt to decode */
memset(&req, 0x00, sizeof(req));
rc = gsm0480_parse_facility_ie(ie, ie_len, &req);
OSMO_ASSERT(rc == 0);
/* Verify expected vs decoded data */
printf("[?] InvokeID: expected 0x%02x, decoded 0x%02x\n",
0x01, req.invoke_id);
printf("[?] Operation code: expected 0x%02x, decoded 0x%02x\n",
0x3c, req.opcode);
printf("[?] Data Coding Scheme: expected 0x%02x, decoded 0x%02x\n",
0x0f, req.ussd_data_dcs);
printf("[?] Data length: expected 0x%02x, decoded 0x%02x\n",
0x01, req.ussd_data_len);
printf("[?] Data: expected %s, decoded %s\n", "32",
osmo_hexdump_nospc(req.ussd_data, req.ussd_data_len));
printf("\n");
}
int main(int argc, char **argv)
{
struct ss_request req;
@ -201,6 +238,9 @@ int main(int argc, char **argv)
/* Test gsm0480_extract_ie_by_tag() */
test_extract_ie_by_tag();
/* Test gsm0480_parse_facility_ie() */
test_parse_facility_ie();
memset(&req, 0, sizeof(req));
gsm0480_decode_ss_request((struct gsm48_hdr *) ussd_request,
sizeof(ussd_request), &req);

8
tests/ussd/ussd_test.ok
View File

@ -4,6 +4,14 @@
[?] FACILITY message with Facility IE (len=18): a2 10 02 01 01 30 0b 02 01 3c 30 06 04 01 0f 04 01 32
[?] RELEASE COMPLETE message with Facility IE (len=8): a3 06 02 01 05 02 01 24
[i] Testing gsm0480_parse_facility_ie()
[?] FACILITY message with Facility IE (len=18): a2 10 02 01 01 30 0b 02 01 3c 30 06 04 01 0f 04 01 32
[?] InvokeID: expected 0x01, decoded 0x01
[?] Operation code: expected 0x3c, decoded 0x3c
[?] Data Coding Scheme: expected 0x0f, decoded 0x0f
[?] Data length: expected 0x01, decoded 0x01
[?] Data: expected 32, decoded 32
Tested if it still works. Text was: **321#
interrogateSS CFU text..'' code 33
Testing parsing a USSD request and truncated versions