Hint for OpenSSL ENGINE / PKCS#11

[opensignature]

I'm writing a new PKCS#11 engine for OpenSSL ( openssl/openssl#8200 ).
Testing with curl I saw that:
curl -E 'pkcs11:object=test' --key 'pkcs11:object=test;pin-value=secret' https://www.saela.eu/auth/index.php
works properly (this is result):

[SSL_CLIENT_VERIFY] = ... self signed certificate
[SSL_CLIENT_SERIAL] = 1EA53B35D50CF1CD1E4A42492518DA318D606A96
[SSL_CLIENT_I_DN] = CN = TEST
[SSL_CLIENT_FINGERPRINT] = 2c0c5a44fa3a9c1e0c5d49fd1a53de75d66c51b0

but with just
curl -E 'pkcs11:object=test; pin-value=secret'
I have
curl: (58) unable to set private key file: 'pkcs11:object=test;pin-value=secret' type PEM
I would like to suggest to insert at https://github.com/curl/curl/blob/master/lib/vtls/openssl.c#L842 these lines:

if (!key_type && do_file_type(cert_type) == SSL_FILETYPE_ENGINE)  {
    file_type = SSL_FILETYPE_ENGINE;
    key_file = cert_file;
}

Best regards,
Antonio

[jay]

Possibly related to #974?

/cc @dwmw2

[dwmw2]

I'd do it like this:

--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -838,15 +838,15 @@ int cert_stuff(struct connectdata *conn,
       return 0;
     }
 
-    file_type = do_file_type(key_type);
+    if(!key_file)
+      key_file = cert_file;
+    else
+      file_type = do_file_type(key_type);
 
     switch(file_type) {
     case SSL_FILETYPE_PEM:
       if(cert_done)
         break;
-      if(!key_file)
-        /* cert & key can only be in PEM case in the same file */
-        key_file = cert_file;
       /* FALLTHROUGH */
     case SSL_FILETYPE_ASN1:
       if(SSL_CTX_use_PrivateKey_file(ctx, key_file, file_type) != 1) {

That works here for both PKCS#11 and file certs.