simutil: add validate_utf8_tlv

Add helper to validate if TLV value is a valid UTF8 string.
Note that both null-terminated and non null-terminated UTF8
strings are considered valid.

src/simutil.c

@@ -765,6 +765,20 @@ unsigned char *comprehension_tlv_builder_get_data(
 	return tlv + tag_size + len_size;
 }
 
+gboolean validate_utf8_tlv(const unsigned char *tlv)
+{
+	int len = tlv[1];
+
+	if (len == 0)
+		return FALSE;
+
+	/* support both null-terminated and non null-terminated TLV value */
+	if (tlv[len + 1] == '\0')
+		len -= 1;
+
+	return g_utf8_validate_len((const char *)tlv + 2, len, NULL);
+}
+
 static char *sim_network_name_parse(const unsigned char *buffer, int length,
 					gboolean *add_ci)
 {

src/simutil.h

@@ -403,6 +403,7 @@ gboolean comprehension_tlv_builder_set_length(
 				unsigned int len);
 unsigned char *comprehension_tlv_builder_get_data(
 				struct comprehension_tlv_builder *builder);
+gboolean validate_utf8_tlv(const unsigned char *data);
 
 void ber_tlv_iter_init(struct ber_tlv_iter *iter, const unsigned char *pdu,
 			unsigned int len);