diff --git a/src/core/include.am b/src/core/include.am
index 5e6e95da13..abbf89f69d 100644
--- a/src/core/include.am
+++ b/src/core/include.am
@@ -138,6 +138,7 @@ LIBTOR_APP_TESTING_A_SOURCES = $(LIBTOR_APP_A_SOURCES)
 
 # The Directory Authority module.
 MODULE_DIRAUTH_SOURCES = 					\
+	src/feature/dirauth/authmode.c				\
 	src/feature/dirauth/dircollate.c			\
 	src/feature/dirauth/dirvote.c				\
 	src/feature/dirauth/shared_random.c			\
diff --git a/src/core/mainloop/connection.c b/src/core/mainloop/connection.c
index 4231bec014..b858b94cd2 100644
--- a/src/core/mainloop/connection.c
+++ b/src/core/mainloop/connection.c
@@ -77,6 +77,7 @@
 #include "core/or/connection_or.h"
 #include "feature/control/control.h"
 #include "lib/crypt_ops/crypto_util.h"
+#include "feature/dirauth/authmode.h"
 #include "feature/dircommon/directory.h"
 #include "feature/dircache/dirserv.h"
 #include "feature/relay/dns.h"
diff --git a/src/core/mainloop/mainloop.c b/src/core/mainloop/mainloop.c
index 105638ffae..6d60b779b8 100644
--- a/src/core/mainloop/mainloop.c
+++ b/src/core/mainloop/mainloop.c
@@ -70,6 +70,7 @@
 #include "lib/crypt_ops/crypto_rand.h"
 #include "feature/dircommon/directory.h"
 #include "feature/dircache/dirserv.h"
+#include "feature/dirauth/authmode.h"
 #include "feature/dirauth/reachability.h"
 #include "feature/relay/dns.h"
 #include "feature/client/dnsserv.h"
diff --git a/src/core/or/circuitstats.c b/src/core/or/circuitstats.c
index 2f37cdfa1a..0429f2c86e 100644
--- a/src/core/or/circuitstats.c
+++ b/src/core/or/circuitstats.c
@@ -43,6 +43,7 @@
 #include "lib/math/fp.h"
 #include "lib/time/tvdiff.h"
 #include "lib/encoding/confline.h"
+#include "feature/dirauth/authmode.h"
 
 #include "core/or/crypt_path_st.h"
 #include "core/or/origin_circuit_st.h"
diff --git a/src/core/or/connection_or.c b/src/core/or/connection_or.c
index ca69fa00d4..7902b6c59d 100644
--- a/src/core/or/connection_or.c
+++ b/src/core/or/connection_or.c
@@ -62,6 +62,7 @@
 #include "core/or/scheduler.h"
 #include "feature/nodelist/torcert.h"
 #include "core/or/channelpadding.h"
+#include "feature/dirauth/authmode.h"
 
 #include "core/or/cell_st.h"
 #include "core/or/cell_queue_st.h"
diff --git a/src/feature/control/fmt_serverstatus.c b/src/feature/control/fmt_serverstatus.c
index f150832ce3..ed9f14ab38 100644
--- a/src/feature/control/fmt_serverstatus.c
+++ b/src/feature/control/fmt_serverstatus.c
@@ -7,6 +7,7 @@
 #include "feature/control/fmt_serverstatus.h"
 
 #include "app/config/config.h"
+#include "feature/dirauth/authmode.h"
 #include "feature/dirauth/voteflags.h"// XXXX remove
 #include "feature/nodelist/nodelist.h"
 #include "feature/relay/router.h"
diff --git a/src/feature/dirauth/authmode.c b/src/feature/dirauth/authmode.c
new file mode 100644
index 0000000000..7c900ea7bf
--- /dev/null
+++ b/src/feature/dirauth/authmode.c
@@ -0,0 +1,70 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file authmode.c
+ * \brief What kind of directory authority are we?
+ *
+ * If we're not an authority, these functions are all replaced with 0 in
+ * authmode.h.
+ **/
+
+#include "core/or/or.h"
+#include "app/config/config.h"
+#include "feature/dirauth/authmode.h"
+
+#include "feature/nodelist/routerinfo_st.h"
+
+/** Return true iff we believe ourselves to be an authoritative
+ * directory server.
+ */
+int
+authdir_mode(const or_options_t *options)
+{
+  return options->AuthoritativeDir != 0;
+}
+/** Return true iff we are an authoritative directory server that is
+ * authoritative about receiving and serving descriptors of type
+ * <b>purpose</b> on its dirport.
+ */
+int
+authdir_mode_handles_descs(const or_options_t *options, int purpose)
+{
+  if (BUG(purpose < 0)) /* Deprecated. */
+    return authdir_mode(options);
+  else if (purpose == ROUTER_PURPOSE_GENERAL)
+    return authdir_mode_v3(options);
+  else if (purpose == ROUTER_PURPOSE_BRIDGE)
+    return authdir_mode_bridge(options);
+  else
+    return 0;
+}
+/** Return true iff we are an authoritative directory server that
+ * publishes its own network statuses.
+ */
+int
+authdir_mode_publishes_statuses(const or_options_t *options)
+{
+  if (authdir_mode_bridge(options))
+    return 0;
+  return authdir_mode(options);
+}
+/** Return true iff we are an authoritative directory server that
+ * tests reachability of the descriptors it learns about.
+ */
+int
+authdir_mode_tests_reachability(const or_options_t *options)
+{
+  return authdir_mode(options);
+}
+/** Return true iff we believe ourselves to be a bridge authoritative
+ * directory server.
+ */
+int
+authdir_mode_bridge(const or_options_t *options)
+{
+  return authdir_mode(options) && options->BridgeAuthoritativeDir != 0;
+}
diff --git a/src/feature/dirauth/authmode.h b/src/feature/dirauth/authmode.h
index 8bb961dffb..3ca127b829 100644
--- a/src/feature/dirauth/authmode.h
+++ b/src/feature/dirauth/authmode.h
@@ -2,16 +2,22 @@
 /* See LICENSE for licensing information */
 
 /**
- * \file mode.h
- * \brief Standalone header file for directory authority mode.
+ * \file authmode.h
+ * \brief Header file for directory authority mode.
  **/
 
 #ifndef TOR_DIRAUTH_MODE_H
 #define TOR_DIRAUTH_MODE_H
 
+#include "feature/relay/router.h"
+
 #ifdef HAVE_MODULE_DIRAUTH
 
-#include "feature/relay/router.h"
+int authdir_mode(const or_options_t *options);
+int authdir_mode_handles_descs(const or_options_t *options, int purpose);
+int authdir_mode_publishes_statuses(const or_options_t *options);
+int authdir_mode_tests_reachability(const or_options_t *options);
+int authdir_mode_bridge(const or_options_t *options);
 
 /* Return true iff we believe ourselves to be a v3 authoritative directory
  * server. */
@@ -23,16 +29,14 @@ authdir_mode_v3(const or_options_t *options)
 
 #else /* HAVE_MODULE_DIRAUTH */
 
-/* Without the dirauth module, we can't be a v3 directory authority, ever. */
-
-static inline int
-authdir_mode_v3(const or_options_t *options)
-{
-  (void) options;
-  return 0;
-}
+#define authdir_mode(options) (((void)(options)),0)
+#define authdir_mode_handles_descs(options,purpose) \
+  (((void)(options)),((void)(purpose)),0)
+#define authdir_mode_publishes_statuses(options) (((void)(options)),0)
+#define authdir_mode_tests_reachability(options) (((void)(options)),0)
+#define authdir_mode_bridge(options) (((void)(options)),0)
+#define authdir_mode_v3(options) (((void)(options)),0)
 
 #endif /* HAVE_MODULE_DIRAUTH */
 
 #endif /* TOR_MODE_H */
-
diff --git a/src/feature/dirauth/reachability.c b/src/feature/dirauth/reachability.c
index abc7249b65..79c98d3ee9 100644
--- a/src/feature/dirauth/reachability.c
+++ b/src/feature/dirauth/reachability.c
@@ -16,6 +16,7 @@
 #include "core/or/channel.h"
 #include "core/or/channeltls.h"
 #include "core/or/command.h"
+#include "feature/dirauth/authmode.h"
 #include "feature/nodelist/nodelist.h"
 #include "feature/nodelist/routerlist.h"
 #include "feature/nodelist/torcert.h"
diff --git a/src/feature/nodelist/authcert.c b/src/feature/nodelist/authcert.c
index e070cb1424..665105e606 100644
--- a/src/feature/nodelist/authcert.c
+++ b/src/feature/nodelist/authcert.c
@@ -23,6 +23,7 @@
 #include "core/mainloop/mainloop.h"
 #include "core/or/policies.h"
 #include "feature/client/bridges.h"
+#include "feature/dirauth/authmode.h"
 #include "feature/dircommon/directory.h"
 #include "feature/dirclient/dirclient.h"
 #include "feature/dirclient/dlstatus.h"
diff --git a/src/feature/nodelist/dirlist.c b/src/feature/nodelist/dirlist.c
index 0935145d88..c14d7df0f0 100644
--- a/src/feature/nodelist/dirlist.c
+++ b/src/feature/nodelist/dirlist.c
@@ -29,6 +29,7 @@
 #include "app/config/config.h"
 #include "core/or/policies.h"
 #include "feature/control/control.h"
+#include "feature/dirauth/authmode.h"
 #include "feature/dircommon/directory.h"
 #include "feature/nodelist/dirlist.h"
 #include "feature/nodelist/networkstatus.h"
diff --git a/src/feature/relay/router.c b/src/feature/relay/router.c
index 3e19c7b619..cc5c424fec 100644
--- a/src/feature/relay/router.c
+++ b/src/feature/relay/router.c
@@ -1348,57 +1348,6 @@ net_is_completely_disabled(void)
   return get_options()->DisableNetwork || we_are_fully_hibernating();
 }
 
-/** Return true iff we believe ourselves to be an authoritative
- * directory server.
- */
-int
-authdir_mode(const or_options_t *options)
-{
-  return options->AuthoritativeDir != 0;
-}
-/** Return true iff we are an authoritative directory server that is
- * authoritative about receiving and serving descriptors of type
- * <b>purpose</b> on its dirport.
- */
-int
-authdir_mode_handles_descs(const or_options_t *options, int purpose)
-{
-  if (BUG(purpose < 0)) /* Deprecated. */
-    return authdir_mode(options);
-  else if (purpose == ROUTER_PURPOSE_GENERAL)
-    return authdir_mode_v3(options);
-  else if (purpose == ROUTER_PURPOSE_BRIDGE)
-    return authdir_mode_bridge(options);
-  else
-    return 0;
-}
-/** Return true iff we are an authoritative directory server that
- * publishes its own network statuses.
- */
-int
-authdir_mode_publishes_statuses(const or_options_t *options)
-{
-  if (authdir_mode_bridge(options))
-    return 0;
-  return authdir_mode(options);
-}
-/** Return true iff we are an authoritative directory server that
- * tests reachability of the descriptors it learns about.
- */
-int
-authdir_mode_tests_reachability(const or_options_t *options)
-{
-  return authdir_mode(options);
-}
-/** Return true iff we believe ourselves to be a bridge authoritative
- * directory server.
- */
-int
-authdir_mode_bridge(const or_options_t *options)
-{
-  return authdir_mode(options) && options->BridgeAuthoritativeDir != 0;
-}
-
 /** Return true iff we are trying to be a server.
  */
 MOCK_IMPL(int,
diff --git a/src/feature/relay/router.h b/src/feature/relay/router.h
index 52c4ac0bd6..7b33069aac 100644
--- a/src/feature/relay/router.h
+++ b/src/feature/relay/router.h
@@ -61,12 +61,6 @@ int dir_server_mode(const or_options_t *options);
 int net_is_disabled(void);
 int net_is_completely_disabled(void);
 
-int authdir_mode(const or_options_t *options);
-int authdir_mode_handles_descs(const or_options_t *options, int purpose);
-int authdir_mode_publishes_statuses(const or_options_t *options);
-int authdir_mode_tests_reachability(const or_options_t *options);
-int authdir_mode_bridge(const or_options_t *options);
-
 uint16_t router_get_active_listener_port_by_type_af(int listener_type,
                                                     sa_family_t family);
 uint16_t router_get_advertised_or_port(const or_options_t *options);
diff --git a/src/feature/stats/rephist.c b/src/feature/stats/rephist.c
index 24c73554be..210576b9e9 100644
--- a/src/feature/stats/rephist.c
+++ b/src/feature/stats/rephist.c
@@ -90,6 +90,7 @@
 #include "core/or/channelpadding.h"
 #include "core/or/connection_or.h"
 #include "app/config/statefile.h"
+#include "feature/dirauth/authmode.h"
 
 #include "feature/nodelist/networkstatus_st.h"
 #include "core/or/or_circuit_st.h"