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
diff --git a/src/gsm/gsm0480.c b/src/gsm/gsm0480.c
index dfd9877..300c0ed 100644
--- a/src/gsm/gsm0480.c
+++ b/src/gsm/gsm0480.c
@@ -201,8 +201,6 @@
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 @@
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 @@
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 @@
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 @@
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 */