build: allow configuring default for wifi.backend setting

Distributions may want to change the default wifi.backend, if for
example they are building without wpa_supplicant support.

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/869

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1040

Makefile.am

@@ -202,7 +202,8 @@ data_edit = sed \
 	-e 's|@NM_CONFIG_DEFAULT_LOGGING_BACKEND_TEXT[@]|$(NM_CONFIG_DEFAULT_LOGGING_BACKEND_TEXT)|g' \
 	-e 's|@NM_CONFIG_DEFAULT_LOGGING_AUDIT_TEXT[@]|$(NM_CONFIG_DEFAULT_LOGGING_AUDIT_TEXT)|g' \
 	-e 's|@NM_CONFIG_DEFAULT_MAIN_RC_MANAGER[@]|$(NM_CONFIG_DEFAULT_MAIN_RC_MANAGER)|g' \
-	-e 's|@NM_CONFIG_DEFAULT_MAIN_DHCP[@]|$(NM_CONFIG_DEFAULT_MAIN_DHCP)|g'
+	-e 's|@NM_CONFIG_DEFAULT_MAIN_DHCP[@]|$(NM_CONFIG_DEFAULT_MAIN_DHCP)|g' \
+	-e 's|@NM_CONFIG_DEFAULT_WIFI_BACKEND_TEXT[@]|$(NM_CONFIG_DEFAULT_WIFI_BACKEND_TEXT)|g'
 
 ###############################################################################
 

config.h.meson

@@ -100,6 +100,9 @@
 /* Default value for main.rc-manager setting */
 #mesondefine NM_CONFIG_DEFAULT_MAIN_RC_MANAGER
 
+/* Default configuration option for wifi.backend */
+#mesondefine NM_CONFIG_DEFAULT_WIFI_BACKEND
+
 /* Define the distribution version string */
 #mesondefine NM_DIST_VERSION
 

configure.ac

@@ -404,6 +404,25 @@ AC_DEFINE_UNQUOTED(NM_CONFIG_DEFAULT_LOGGING_BACKEND, "$nm_config_logging_backen
 NM_CONFIG_DEFAULT_LOGGING_BACKEND_TEXT="$nm_config_logging_backend_default"
 AC_SUBST(NM_CONFIG_DEFAULT_LOGGING_BACKEND_TEXT)
 
+AC_ARG_WITH(config-wifi-backend-default,
+            AS_HELP_STRING([--with-config-wifi-backend-default=backend],
+                           [Default value for wifi.backend]),
+            nm_config_wifi_backend_default="$withval",
+            nm_config_wifi_backend_default="wpa_supplicant")
+
+if test "$nm_config_wifi_backend_default" != 'iwd' \
+     -a "$nm_config_wifi_backend_default" != 'wpa_supplicant'; then
+	AC_MSG_ERROR([The default Wi-Fi backend must be either wpa_supplicant or iwd.])
+fi
+if test "$nm_config_wifi_backend_default" = "iwd"; then
+	if test "$ac_with_iwd" != "yes"; then
+		AC_MSG_ERROR([Setting the default Wi-Fi backend to iwd requires iwd support.])
+	fi
+fi
+AC_DEFINE_UNQUOTED(NM_CONFIG_DEFAULT_WIFI_BACKEND, "$nm_config_wifi_backend_default", [Default configuration option for wifi.backend])
+NM_CONFIG_DEFAULT_WIFI_BACKEND_TEXT="$nm_config_wifi_backend_default"
+AC_SUBST(NM_CONFIG_DEFAULT_WIFI_BACKEND_TEXT)
+
 # Session tracking support
 AC_ARG_WITH(systemd-logind,
             AS_HELP_STRING([--with-systemd-logind=yes|no],

contrib/fedora/rpm/build_clean.sh

@@ -198,6 +198,7 @@ if [[ $NO_DIST != 1 ]]; then
         --enable-ifcfg-rh \
         --enable-ifupdown \
         --with-config-logging-backend-default=syslog \
+        --with-config-wifi-backend-default=wpa_supplicant \
         --with-libaudit=yes-disabled-by-default \
         --enable-polkit=yes \
         --with-nm-cloud-setup=yes \

man/NetworkManager.conf.xml

@@ -1237,6 +1237,7 @@ managed=1
             <para>
               Specify the Wi-Fi backend used for the device. Currently, supported
               are <literal>wpa_supplicant</literal> and <literal>iwd</literal> (experimental).
+              If unspecified, the default is "<literal>&NM_CONFIG_DEFAULT_WIFI_BACKEND_TEXT;</literal>".
             </para>
           </listitem>
         </varlistentry>

man/common.ent.in

@@ -8,3 +8,4 @@
 <!ENTITY NM_CONFIG_DEFAULT_LOGGING_AUDIT_TEXT "@NM_CONFIG_DEFAULT_LOGGING_AUDIT_TEXT@">
 <!ENTITY NM_CONFIG_DEFAULT_MAIN_RC_MANAGER "@NM_CONFIG_DEFAULT_MAIN_RC_MANAGER@">
 <!ENTITY NM_CONFIG_DEFAULT_MAIN_DHCP "@NM_CONFIG_DEFAULT_MAIN_DHCP@">
+<!ENTITY NM_CONFIG_DEFAULT_WIFI_BACKEND_TEXT "@NM_CONFIG_DEFAULT_WIFI_BACKEND_TEXT@">

meson.build

@@ -389,6 +389,14 @@ if config_logging_backend_default == 'default'
 endif
 config_h.set_quoted('NM_CONFIG_DEFAULT_LOGGING_BACKEND', config_logging_backend_default)
 
+config_wifi_backend_default = get_option('config_wifi_backend_default')
+if config_wifi_backend_default == 'default'
+  config_wifi_backend_default = 'wpa_supplicant'
+elif config_wifi_backend_default == 'iwd'
+  assert(enable_iwd, 'Setting the default Wi-Fi backend to iwd requires iwd support.')
+endif
+config_h.set_quoted('NM_CONFIG_DEFAULT_WIFI_BACKEND', config_wifi_backend_default)
+
 session_tracking = get_option('session_tracking')
 session_trackers = []
 
@@ -890,6 +898,7 @@ data_conf.set('NM_CONFIG_DEFAULT_LOGGING_BACKEND_TEXT',  config_logging_backend_
 data_conf.set('NM_CONFIG_DEFAULT_MAIN_AUTH_POLKIT_TEXT', config_auth_polkit_default)
 data_conf.set('NM_CONFIG_DEFAULT_MAIN_DHCP',             config_dhcp_default)
 data_conf.set('NM_CONFIG_DEFAULT_MAIN_RC_MANAGER',       config_dns_rc_manager_default)
+data_conf.set('NM_CONFIG_DEFAULT_WIFI_BACKEND_TEXT',     config_wifi_backend_default)
 data_conf.set('NM_MAJOR_VERSION',                        nm_major_version)
 data_conf.set('NM_MICRO_VERSION',                        nm_micro_version)
 data_conf.set('NM_MINOR_VERSION',                        nm_minor_version)

meson_options.txt

@@ -21,6 +21,7 @@ option('polkit_agent_helper_1', type: 'string', value: '', description: 'Path na
 option('selinux', type: 'boolean', value: true, description: 'Build with SELinux')
 option('systemd_journal', type: 'boolean', value: true, description: 'Use systemd journal for logging')
 option('config_logging_backend_default', type: 'combo', choices: ['default', 'syslog', 'journal'], value: 'default', description: 'Default value for logging.backend')
+option('config_wifi_backend_default', type: 'combo', choices: ['default', 'wpa_supplicant', 'iwd'], value: 'default', description: 'Default value for wifi.backend')
 option('hostname_persist', type: 'combo', choices: ['default', 'suse', 'gentoo', 'slackware'], value: 'default', description: 'Hostname persist method')
 option('libaudit', type: 'combo', choices: ['yes', 'yes-disabled-by-default', 'no'], value: 'yes', description: 'Build with audit daemon support. yes-disabled-by-default enables support, but disables it unless explicitly configured via NetworkManager.conf')
 

src/core/devices/wifi/nm-wifi-factory.c

@@ -92,12 +92,15 @@ create_device(NMDeviceFactory      *factory,
                                                          NULL);
     backend = nm_strstrip_avoid_copy_a(300, backend, &backend_free);
 
+    if (!backend)
+        backend = "" NM_CONFIG_DEFAULT_WIFI_BACKEND;
+
     nm_log_dbg(LOGD_PLATFORM | LOGD_WIFI,
                "(%s) config: backend is %s%s%s%s",
                iface,
                NM_PRINT_FMT_QUOTE_STRING(backend),
                WITH_IWD ? " (iwd support enabled)" : "");
-    if (!backend || !g_ascii_strcasecmp(backend, "wpa_supplicant")) {
+    if (!g_ascii_strcasecmp(backend, "wpa_supplicant")) {
         NMDevice                 *device;
         _NMDeviceWifiCapabilities capabilities;
         _NM80211Mode              mode;

src/core/nm-config-data.c

@@ -711,6 +711,9 @@ static const struct {
     {NM_CONFIG_KEYFILE_GROUP_MAIN, NM_CONFIG_KEYFILE_KEY_MAIN_IWD_CONFIG_PATH, ""},
     {NM_CONFIG_KEYFILE_GROUP_LOGGING, "backend", NM_CONFIG_DEFAULT_LOGGING_BACKEND},
     {NM_CONFIG_KEYFILE_GROUP_LOGGING, "audit", NM_CONFIG_DEFAULT_LOGGING_AUDIT},
+    {NM_CONFIG_KEYFILE_GROUPPREFIX_DEVICE,
+     NM_CONFIG_KEYFILE_KEY_DEVICE_WIFI_BACKEND,
+     NM_CONFIG_DEFAULT_WIFI_BACKEND},
 };
 
 void