Define new CONST_TO_*_CONN() functions for const-to-const casts

These names are analogous to the CONST_TO_*_CIRC() functions we have
for circuits.

Part of #40046.

2 files changed, 13 insertions, 0 deletions

diff --git a/src/feature/dircommon/directory.c b/src/feature/dircommon/directory.c
index bb9264eaf9..e92e6480af 100644
--- a/src/feature/dircommon/directory.c
+++ b/src/feature/dircommon/directory.c
@@ -92,6 +92,18 @@ TO_DIR_CONN(connection_t *c)
   return DOWNCAST(dir_connection_t, c);
 }
 
+/**
+ * Cast a `const connection_t *` to a `const dir_connection_t *`.
+ *
+ * Exit with an assertion failure if the input is not a
+ * `dir_connection_t`.
+ **/
+const dir_connection_t *
+CONST_TO_DIR_CONN(const connection_t *c)
+{
+  return TO_DIR_CONN((connection_t *)c);
+}
+
 /** Return false if the directory purpose <b>dir_purpose</b>
  * does not require an anonymous (three-hop) connection.
  *
diff --git a/src/feature/dircommon/directory.h b/src/feature/dircommon/directory.h
index 0f26cdeff9..0aa2ff53ef 100644
--- a/src/feature/dircommon/directory.h
+++ b/src/feature/dircommon/directory.h
@@ -13,6 +13,7 @@
 #define TOR_DIRECTORY_H
 
 dir_connection_t *TO_DIR_CONN(connection_t *c);
+const dir_connection_t *CONST_TO_DIR_CONN(const connection_t *c);
 
 #define DIR_CONN_STATE_MIN_ 1
 /** State for connection to directory server: waiting for connect(). */