From b3eb4091579e59e4bf311713a3bef0f85137b1b0 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Thu, 16 Jul 2020 10:11:13 -0400
Subject: [PATCH] Define const variants for our channel_tls_t* casts.

---
 src/core/or/channeltls.c | 19 +++++++++++++++++++
 src/core/or/channeltls.h |  4 ++++
 2 files changed, 23 insertions(+)

diff --git a/src/core/or/channeltls.c b/src/core/or/channeltls.c
index 082a035c3c..4a421462cc 100644
--- a/src/core/or/channeltls.c
+++ b/src/core/or/channeltls.c
@@ -389,6 +389,25 @@ channel_tls_from_base(channel_t *chan)
   return (channel_tls_t *)(chan);
 }
 
+/**
+ * Cast a const channel_tls_t to a const channel_t.
+ */
+const channel_t *
+channel_tls_to_base_const(const channel_tls_t *tlschan)
+{
+  return channel_tls_to_base((channel_tls_t*) tlschan);
+}
+
+/**
+ * Cast a const channel_t to a const channel_tls_t, with appropriate
+ * type-checking asserts.
+ */
+const channel_tls_t *
+channel_tls_from_base_const(const channel_t *chan)
+{
+  return channel_tls_from_base((channel_t *)chan);
+}
+
 /********************************************
  * Method implementations for channel_tls_t *
  *******************************************/
diff --git a/src/core/or/channeltls.h b/src/core/or/channeltls.h
index f04ce0fa9c..e7010a51fc 100644
--- a/src/core/or/channeltls.h
+++ b/src/core/or/channeltls.h
@@ -19,6 +19,8 @@ struct curve25519_public_key_t;
 
 #define BASE_CHAN_TO_TLS(c) (channel_tls_from_base((c)))
 #define TLS_CHAN_TO_BASE(c) (channel_tls_to_base((c)))
+#define CONST_BASE_CHAN_TO_TLS(c) (channel_tls_from_base_const((c)))
+#define CONST_TLS_CHAN_TO_BASE(c) (channel_tls_to_base_const((c)))
 
 #define TLS_CHAN_MAGIC 0x8a192427U
 
@@ -44,6 +46,8 @@ channel_t * channel_tls_handle_incoming(or_connection_t *orconn);
 
 channel_t * channel_tls_to_base(channel_tls_t *tlschan);
 channel_tls_t * channel_tls_from_base(channel_t *chan);
+const channel_t * channel_tls_to_base_const(const channel_tls_t *tlschan);
+const channel_tls_t * channel_tls_from_base_const(const channel_t *chan);
 
 /* Things for connection_or.c to call back into */
 void channel_tls_handle_cell(cell_t *cell, or_connection_t *conn);