Test accessors to config DN hints for cert request

Signed-off-by: Glenn Strauss <gstrauss@gluelogic.com>
diff --git a/library/ssl_tls12_client.c b/library/ssl_tls12_client.c
index f516efa..35f11ea 100644
--- a/library/ssl_tls12_client.c
+++ b/library/ssl_tls12_client.c
@@ -2534,6 +2534,7 @@
     size_t sig_alg_len;
 #if defined(MBEDTLS_DEBUG_C)
         unsigned char *sig_alg;
+        unsigned char *dn;
 #endif
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate request" ) );
@@ -2681,6 +2682,43 @@
         return( MBEDTLS_ERR_SSL_DECODE_ERROR );
     }
 
+#if defined(MBEDTLS_DEBUG_C)
+    dn = buf + mbedtls_ssl_hs_hdr_len( ssl ) + 3 + n - dn_len;
+    for( size_t i = 0, dni_len = 0; i < dn_len; i += 2 + dni_len )
+    {
+        unsigned char *p = dn + i + 2;
+        mbedtls_x509_name name;
+        mbedtls_x509_name *name_cur, *name_prv;
+        size_t asn1_len;
+        char s[MBEDTLS_X509_MAX_DN_NAME_SIZE];
+        memset( &name, 0, sizeof( name ) );
+        dni_len = MBEDTLS_GET_UINT16_BE( dn + i, 0 );
+        if( dni_len > dn_len - i - 2 ||
+            mbedtls_asn1_get_tag( &p, p + dni_len, &asn1_len,
+              MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) != 0 ||
+            mbedtls_x509_get_name( &p, p + asn1_len, &name ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
+            mbedtls_ssl_send_alert_message(
+                ssl,
+                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+        }
+        MBEDTLS_SSL_DEBUG_MSG( 3,
+            ( "DN hint: %.*s",
+              mbedtls_x509_dn_gets( s, sizeof(s), &name ), s ) );
+        name_cur = name.next;
+        while( name_cur != NULL )
+        {
+            name_prv = name_cur;
+            name_cur = name_cur->next;
+            mbedtls_platform_zeroize( name_prv, sizeof( mbedtls_x509_name ) );
+            mbedtls_free( name_prv );
+        }
+    }
+#endif
+
 exit:
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate request" ) );