fff-babel: Make implementation runtime switchable

Some users might want to prefer one babel implementation over another
for various reasons. Having to compile the firmware from scratch can be
quite tedious in that case.

Instead, make the babel implementation switchable at runtime.

Currently, the implementation has to be switched manually in
/lib/functions/fff/babel, which is not upgrade-safe. Also, the previous
implementation is currently not restored after test-mode, so switching
implementations should not be done with test-mode.

Signed-off-by: Fabian Bläse <fabian@blaese.de>

src/packages/fff/fff-babel-bird2/Makefile

@@ -12,7 +12,6 @@ define Package/fff-babel-bird2
 	URL:=https://www.freifunk-franken.de
 	DEPENDS:=+bird2 +bird2c
 	PROVIDES:=fff-babel-implementation
-	CONFLICTS:=fff-babeld
 endef
 
 define Package/fff-babel-bird2/description

src/packages/fff/fff-babel-bird2/files/etc/uci-defaults/30-disable-bird2

@@ -0,0 +1,3 @@
+/etc/init.d/bird disable
+
+exit 0

src/packages/fff/fff-babel-bird2/files/lib/functions/fff/babeldaemon/bird2

@@ -44,7 +44,7 @@ babel_apply() {
 	return 0
 }
 
-babel_reload() {
+babel_reload_implementation() {
 	# Change include file path, so bird uses the correct configuration, depending on the configuration state:
 	#  - If test mode is active (and /tmp/bird-babel exists), switch to the temporary (/tmp) configuration to be tested.
 	#  - If new settings are applied or the old settings are restored after an unsuccessful test (and /tmp/bird-babel does not exist),

src/packages/fff/fff-babel/files/lib/functions/fff/babel

@@ -1,4 +1,6 @@
-. /lib/functions/fff/babeldaemon
+
+implementation=babeld
+. /lib/functions/fff/babeldaemon/$implementation
 
 babel_add_iifrules() {
 	[ "$#" -ne "1" ] && return 1
@@ -62,3 +64,26 @@ babel_add_peer6addr() {
 
 	return 0
 }
+
+babel_reload() {
+	# switch implementation
+	case $implementation in
+		bird2)
+			/etc/init.d/babeld stop 2>/dev/null
+			/etc/init.d/babeld disable
+			/etc/init.d/bird enable
+			/etc/init.d/bird start
+			;;
+		babeld)
+			/etc/init.d/bird stop 2>/dev/null
+			/etc/init.d/bird disable
+			/etc/init.d/babeld enable
+			/etc/init.d/babeld start
+			;;
+	esac
+
+	# call implementation-specific reload commands
+	babel_reload_implementation
+
+	return 0
+}

src/packages/fff/fff-babeld/files/etc/uci-defaults/30-disable-babeld

@@ -0,0 +1,3 @@
+/etc/init.d/babeld disable
+
+exit 0

src/packages/fff/fff-babeld/files/lib/functions/fff/babeldaemon/babeld

@@ -63,7 +63,7 @@ babel_apply() {
 	uci commit babeld
 }
 
-babel_reload() {
+babel_reload_implementation() {
 	return 0
 }
 

src/packages/fff/fff-layer3/Makefile

@@ -13,6 +13,7 @@ define Package/fff-layer3
 	DEPENDS:=+fff-alfred-monitoring-proxy \
 	         +fff-babel \
 	         +fff-babeld \
+	         +fff-babel-bird2 \
 	         +fff-boardname \
 	         +fff-dhcp \
 	         +fff-layer3-config \