--- /dev/null
+/* $OpenBSD: asn1_string_to_utf8.c,v 1.1 2022/05/16 20:53:20 tb Exp $ */
+/*
+ * Copyright (c) 2022 Theo Buehler <tb@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <err.h>
+#include <string.h>
+
+#include <openssl/asn1.h>
+
+struct asn1_string_to_utf8_test_case {
+ const char *description;
+ const ASN1_ITEM *item;
+ const uint8_t der[32];
+ size_t der_len;
+ const uint8_t want[32];
+ int want_len;
+};
+
+static const struct asn1_string_to_utf8_test_case tests[] = {
+ {
+ .description = "hello",
+ .item = &ASN1_PRINTABLESTRING_it,
+ .der = {
+ 0x13, 0x05, 0x68, 0x65, 0x6c, 0x6c, 0x6f,
+ },
+ .der_len = 7,
+ .want = {
+ 0x68, 0x65, 0x6c, 0x6c, 0x6f,
+ },
+ .want_len = 5,
+ },
+ {
+ .description = "face with tears of joy",
+ .item = &ASN1_UTF8STRING_it,
+ .der = {
+ 0x0c, 0x04, 0xF0, 0x9F, 0x98, 0x82,
+ },
+ .der_len = 6,
+ .want = {
+ 0xF0, 0x9F, 0x98, 0x82,
+ },
+ .want_len = 4,
+ },
+ {
+ .description = "hi",
+ .item = &ASN1_IA5STRING_it,
+ .der = {
+ 0x16, 0x02, 0x68, 0x69,
+ },
+ .der_len = 4,
+ .want = {
+ 0x68, 0x69,
+ },
+ .want_len = 2,
+ },
+};
+
+const size_t N_TESTS = sizeof(tests) / sizeof(tests[0]);
+
+static int
+asn1_string_to_utf8_test(const struct asn1_string_to_utf8_test_case *test)
+{
+ ASN1_STRING *str = NULL;
+ const unsigned char *der;
+ unsigned char *out = NULL;
+ int ret;
+ int failed = 1;
+
+ der = test->der;
+ if ((str = (ASN1_STRING *)ASN1_item_d2i(NULL, &der, test->der_len,
+ test->item)) == NULL) {
+ warnx("ASN1_item_d2i failed");
+ goto err;
+ }
+
+ if ((ret = ASN1_STRING_to_UTF8(&out, str)) != test->want_len) {
+ warnx("ASN1_STRING_to_UTF8 failed: got %d, want %d", ret,
+ test->want_len);
+ goto err;
+ }
+
+ if (memcmp(out, test->want, test->want_len) != 0) {
+ warnx("memcmp failed");
+ goto err;
+ }
+
+ failed = 0;
+ err:
+ ASN1_STRING_free(str);
+ free(out);
+
+ return failed;
+}
+
+static int
+asn1_string_to_utf8_tests(void)
+{
+ size_t i;
+ int failed = 0;
+
+ for (i = 0; i < N_TESTS; i++)
+ failed |= asn1_string_to_utf8_test(&tests[i]);
+
+ return failed;
+}
+
+int
+main(void)
+{
+ int failed = 0;
+
+ failed |= asn1_string_to_utf8_tests();
+
+ return failed;
+}