gprs: Add gprs_shift_tlv function
This function is similar to gprs_match_tlv with the exception, that
the tag is not compared but returned in *tag instead.
Sponsored-by: On-Waves ehf
diff --git a/openbsc/include/openbsc/gprs_utils.h b/openbsc/include/openbsc/gprs_utils.h
index 60d0ef6..60b55a1 100644
--- a/openbsc/include/openbsc/gprs_utils.h
+++ b/openbsc/include/openbsc/gprs_utils.h
@@ -40,6 +40,8 @@
size_t len, uint8_t **value);
int gprs_match_tv_fixed(uint8_t **data, size_t *data_len,
uint8_t tag, size_t len, uint8_t **value);
+int gprs_shift_tlv(uint8_t **data, size_t *data_len,
+ uint8_t *tag, uint8_t **value, size_t *value_len);
int gprs_match_tlv(uint8_t **data, size_t *data_len,
uint8_t tag, uint8_t **value, size_t *value_len);
int gprs_shift_lv(uint8_t **data, size_t *data_len,
diff --git a/openbsc/src/gprs/gprs_utils.c b/openbsc/src/gprs/gprs_utils.c
index cec07d7..55bc629 100644
--- a/openbsc/src/gprs/gprs_utils.c
+++ b/openbsc/src/gprs/gprs_utils.c
@@ -271,7 +271,26 @@
}
int gprs_match_tlv(uint8_t **data, size_t *data_len,
- uint8_t tag, uint8_t **value, size_t *value_len)
+ uint8_t expected_tag, uint8_t **value, size_t *value_len)
+{
+ int rc;
+ uint8_t tag;
+ uint8_t *old_data = *data;
+ size_t old_data_len = *data_len;
+
+ rc = gprs_shift_tlv(data, data_len, &tag, value, value_len);
+
+ if (rc > 0 && tag != expected_tag) {
+ *data = old_data;
+ *data_len = old_data_len;
+ return 0;
+ }
+
+ return rc;
+}
+
+int gprs_shift_tlv(uint8_t **data, size_t *data_len,
+ uint8_t *tag, uint8_t **value, size_t *value_len)
{
size_t len;
size_t ie_len;
@@ -279,13 +298,12 @@
if (*data_len < 2)
goto fail;
- if ((*data)[0] != tag)
- return 0;
-
len = (*data)[1];
if (len > *data_len - 2)
goto fail;
+ if (tag)
+ *tag = (*data)[0];
if (value)
*value = *data + 2;
if (value_len)
diff --git a/openbsc/tests/gprs/gprs_test.c b/openbsc/tests/gprs/gprs_test.c
index 5bc2073..1b20db1 100644
--- a/openbsc/tests/gprs/gprs_test.c
+++ b/openbsc/tests/gprs/gprs_test.c
@@ -139,20 +139,33 @@
}
/* TODO: Move tlv testing to libosmocore */
-static void check_tlv_match(uint8_t **data, size_t *data_len,
- uint8_t tag, size_t exp_len, const uint8_t *exp_val)
+static void check_tlv_parse(uint8_t **data, size_t *data_len,
+ uint8_t exp_tag, size_t exp_len, const uint8_t *exp_val)
{
uint8_t *value;
size_t value_len;
+ uint8_t tag;
int rc;
+ uint8_t *saved_data = *data;
+ size_t saved_data_len = *data_len;
- rc = gprs_match_tlv(data, data_len, tag ^ 1, NULL, NULL);
+ rc = gprs_match_tlv(data, data_len, exp_tag ^ 1, NULL, NULL);
OSMO_ASSERT(rc == 0);
- rc = gprs_match_tlv(data, data_len, tag, &value, &value_len);
+ rc = gprs_match_tlv(data, data_len, exp_tag, &value, &value_len);
OSMO_ASSERT(rc == (int)value_len + 2);
OSMO_ASSERT(value_len == exp_len);
OSMO_ASSERT(memcmp(value, exp_val, exp_len) == 0);
+
+ /* restore data/data_len */
+ *data = saved_data;
+ *data_len = saved_data_len;
+
+ rc = gprs_shift_tlv(data, data_len, &tag, &value, &value_len);
+ OSMO_ASSERT(rc == (int)value_len + 2);
+ OSMO_ASSERT(tag == exp_tag);
+ OSMO_ASSERT(value_len == exp_len);
+ OSMO_ASSERT(memcmp(value, exp_val, exp_len) == 0);
}
static void check_tv_fixed_match(uint8_t **data, size_t *data_len,
@@ -340,7 +353,7 @@
OSMO_ASSERT(data_len <= sizeof(buf));
for (i = 0; i < iterations; i++) {
- check_tlv_match(&data, &data_len, tag, len, test_data);
+ check_tlv_parse(&data, &data_len, tag, len, test_data);
check_tv_fixed_match(&data, &data_len, tag, len, test_data);
check_v_fixed_shift(&data, &data_len, len, test_data);
check_lv_shift(&data, &data_len, len, test_data);