fuzzers: print and convert it back

Reviewed-by: Rich Salz <rsalz@openssl.org>
GH: #1323

1 files changed, 23 insertions, 1 deletions

diff --git a/fuzz/asn1.c b/fuzz/asn1.c
index 5d871cd2dd..4d5a726029 100644
--- a/fuzz/asn1.c
+++ b/fuzz/asn1.c
@@ -69,11 +69,33 @@ int FuzzerInitialize(int *argc, char ***argv) {
 int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     int n;
 
+    ASN1_PCTX *pctx = ASN1_PCTX_new();
+
+    ASN1_PCTX_set_flags(pctx, ASN1_PCTX_FLAGS_SHOW_ABSENT |
+        ASN1_PCTX_FLAGS_SHOW_SEQUENCE | ASN1_PCTX_FLAGS_SHOW_SSOF |
+        ASN1_PCTX_FLAGS_SHOW_TYPE | ASN1_PCTX_FLAGS_SHOW_FIELD_STRUCT_NAME);
+    ASN1_PCTX_set_str_flags(pctx, ASN1_STRFLGS_UTF8_CONVERT |
+        ASN1_STRFLGS_SHOW_TYPE | ASN1_STRFLGS_DUMP_ALL);
+
     for (n = 0; item_type[n] != NULL; ++n) {
         const uint8_t *b = buf;
+        unsigned char *der = NULL;
         const ASN1_ITEM *i = ASN1_ITEM_ptr(item_type[n]);
         ASN1_VALUE *o = ASN1_item_d2i(NULL, &b, len, i);
-        ASN1_item_free(o, i);
+
+        if (o != NULL) {
+            BIO *bio = BIO_new(BIO_s_null());
+            ASN1_item_print(bio, o, 4, i, pctx);
+            BIO_free(bio);
+
+            ASN1_item_i2d(o, &der, i);
+            OPENSSL_free(der);
+
+            ASN1_item_free(o, i);
+        }
     }
+
+    ASN1_PCTX_free(pctx);
+
     return 0;
 }