winhttp: Use sk_ functions rather than accessing an OpenSSL stack type directly.

dlls/winhttp/net.c

@@ -124,6 +124,8 @@ MAKE_FUNCPTR( ERR_get_error );
 MAKE_FUNCPTR( ERR_error_string );
 MAKE_FUNCPTR( X509_STORE_CTX_get_ex_data );
 MAKE_FUNCPTR( i2d_X509 );
+MAKE_FUNCPTR( sk_value );
+MAKE_FUNCPTR( sk_num );
 #undef MAKE_FUNCPTR
 
 static CRITICAL_SECTION *ssl_locks;
@@ -339,11 +341,11 @@ static int netconn_secure_verify( int preverify_ok, X509_STORE_CTX *ctx )
             PCCERT_CONTEXT endCert = NULL;
 
             ret = TRUE;
-            for (i = 0; ret && i < ctx->chain->num; i++)
+            for (i = 0; ret && i < psk_num((struct stack_st *)ctx->chain); i++)
             {
                 PCCERT_CONTEXT context;
 
-                cert = (X509 *)ctx->chain->data[i];
+                cert = (X509 *)psk_value((struct stack_st *)ctx->chain, i);
                 if ((context = X509_to_cert_context( cert )))
                 {
                     if (i == 0)
@@ -441,6 +443,8 @@ BOOL netconn_init( netconn_t *conn, BOOL secure )
     LOAD_FUNCPTR( ERR_error_string );
     LOAD_FUNCPTR( X509_STORE_CTX_get_ex_data );
     LOAD_FUNCPTR( i2d_X509 );
+    LOAD_FUNCPTR( sk_value );
+    LOAD_FUNCPTR( sk_num );
 #undef LOAD_FUNCPTR
 
     pSSL_library_init();