1 files changed, 26 insertions, 6 deletions

diff --git a/src/core/or/crypt_path_st.h b/src/core/or/crypt_path_st.h
index 429480f8ab..2b69728a6d 100644
--- a/src/core/or/crypt_path_st.h
+++ b/src/core/or/crypt_path_st.h
@@ -1,9 +1,14 @@
 /* Copyright (c) 2001 Matej Pfajfar.
  * Copyright (c) 2001-2004, Roger Dingledine.
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+/**
+ * @file crypt_path_st.h
+ * @brief Path structures for origin circuits.
+ **/
+
 #ifndef CRYPT_PATH_ST_H
 #define CRYPT_PATH_ST_H
 
@@ -24,15 +29,24 @@ struct onion_handshake_state_t {
   } u;
 };
 
+/** Macro to encapsulate private members of a struct.
+ *
+ *  Renames 'x' to 'x_crypt_path_private_field'.
+ */
+#define CRYPT_PATH_PRIV_FIELD(x) x ## _crypt_path_private_field
+
+#ifdef CRYPT_PATH_PRIVATE
+
+/* Helper macro to access private members of a struct. */
+#define pvt_crypto CRYPT_PATH_PRIV_FIELD(crypto)
+
+#endif /* defined(CRYPT_PATH_PRIVATE) */
+
 /** Holds accounting information for a single step in the layered encryption
  * performed by a circuit.  Used only at the client edge of a circuit. */
 struct crypt_path_t {
   uint32_t magic;
 
-  /** Cryptographic state used for encrypting and authenticating relay
-   * cells to and from this hop. */
-  relay_crypto_t crypto;
-
   /** Current state of the handshake as performed with the OR at this
    * step. */
   onion_handshake_state_t handshake_state;
@@ -65,6 +79,12 @@ struct crypt_path_t {
                        * at this step? */
   int deliver_window; /**< How many cells are we willing to deliver originating
                        * at this step? */
+
+  /*********************** Private members ****************************/
+
+  /** Private member: Cryptographic state used for encrypting and
+   * authenticating relay cells to and from this hop. */
+  relay_crypto_t CRYPT_PATH_PRIV_FIELD(crypto);
 };
 
-#endif
+#endif /* !defined(CRYPT_PATH_ST_H) */