tlv: add TLV_GET() and TLV_GET_MINLEN()
Rationale: so far we use code like
if (TLVP_PRESENT(&tp, VERY_LONG_ENUM_VALUE_NAME_THAT_NEVER_ENDS)) {
val = TLVP_VAL(&tp, VERY_LONG_ENUM_VALUE_NAME_THAT_NEVER_ENDS);
len = TLVP_LEN(&tp, VERY_L0NG_ENUM_VALUE_NAME_TH4T_NEVER_EMDS);
}
This is a) very long and b) prone to picking the wrong name one of the three
times, which would use the wrong length or val without necessarily being
noticed. A safer and shorter, more readable pattern is:
struct tlv_p_entry *e = TVLP_GET(&tp, VERY_LONG_ENUM_VALUE_NAME_THAT_NEVER_ENDS);
if (!e)
return -ENOENT;
hexdump(e->val, e->len);
Change-Id: I445de17fc2daa3ab051f5708dd0cc185b23dc048
diff --git a/include/osmocom/gsm/tlv.h b/include/osmocom/gsm/tlv.h
index 996f6aa..a130dc8 100644
--- a/include/osmocom/gsm/tlv.h
+++ b/include/osmocom/gsm/tlv.h
@@ -446,6 +446,27 @@
#define TLVP_PRES_LEN(tp, tag, min_len) \
(TLVP_PRESENT(tp, tag) && TLVP_LEN(tp, tag) >= min_len)
+/*! Return pointer to a TLV element if it is present.
+ * Usage:
+ * struct tlv_p_entry *e = TVLP_GET(&tp, TAG);
+ * if (!e)
+ * return -ENOENT;
+ * hexdump(e->val, e->len);
+ * \param[in] _tp pointer to \ref tlv_parsed.
+ * \param[in] tag IE tag to return.
+ * \returns struct tlv_p_entry pointer, or NULL if not present.
+ */
+#define TLVP_GET(_tp, tag) (TLVP_PRESENT(_tp, tag)? &(_tp)->lv[tag] : NULL)
+
+/*! Like TLVP_GET(), but enforcing a minimum val length.
+ * \param[in] _tp pointer to \ref tlv_parsed.
+ * \param[in] tag IE tag to return.
+ * \param[in] min_len Minimum value length in bytes.
+ * \returns struct tlv_p_entry pointer, or NULL if not present or too short.
+ */
+#define TLVP_GET_MINLEN(_tp, tag, min_len) \
+ (TLVP_PRES_LEN(_tp, tag, min_len)? &(_tp)->lv[tag] : NULL)
+
/*! Align given TLV element with 16 bit value to an even address
* \param[in] tp pointer to \ref tlv_parsed
* \param[in] pos element to return