openssl: fix pubkey/signature algorithm detection in certinfo

Certinfo gives the same result for all OpenSSL versions.
Also made printing RSA pubkeys consistent with older versions.

Reported-by: Michael Wallner
Fixes curl#3706
Closes curl#4030

lib/vtls/openssl.c

@@ -3085,18 +3085,25 @@ static CURLcode get_cert_chain(struct connectdata *conn,
 
 #if defined(HAVE_X509_GET0_SIGNATURE) && defined(HAVE_X509_GET0_EXTENSIONS)
     {
-      const X509_ALGOR *palg = NULL;
-      ASN1_STRING *a = ASN1_STRING_new();
-      if(a) {
-        X509_get0_signature(&psig, &palg, x);
-        X509_signature_print(mem, ARG2_X509_signature_print palg, a);
-        ASN1_STRING_free(a);
-
-        if(palg) {
-          i2a_ASN1_OBJECT(mem, palg->algorithm);
+      const X509_ALGOR *sigalg = NULL;
+      X509_PUBKEY *xpubkey = NULL;
+      ASN1_OBJECT *pubkeyoid = NULL;
+
+      X509_get0_signature(&psig, &sigalg, x);
+      if(sigalg) {
+        i2a_ASN1_OBJECT(mem, sigalg->algorithm);
+        push_certinfo("Signature Algorithm", i);
+      }
+
+      xpubkey = X509_get_X509_PUBKEY(x);
+      if(xpubkey) {
+        X509_PUBKEY_get0_param(&pubkeyoid, NULL, NULL, NULL, xpubkey);
+        if(pubkeyoid) {
+          i2a_ASN1_OBJECT(mem, pubkeyoid);
           push_certinfo("Public Key Algorithm", i);
         }
       }
+
       X509V3_ext(data, i, X509_get0_extensions(x));
     }
 #else
@@ -3148,7 +3155,7 @@ static CURLcode get_cert_chain(struct connectdata *conn,
           const BIGNUM *e;
 
           RSA_get0_key(rsa, &n, &e, NULL);
-          BN_print(mem, n);
+          BIO_printf(mem, "%d", BN_num_bits(n));
           push_certinfo("RSA Public Key", i);
           print_pubkey_BN(rsa, n, i);
           print_pubkey_BN(rsa, e, i);