tunneldigger-broker: add broker for tunneldigger

In mesh communities, tunneldigger is widely used to create L2TPv3 tunnels
and mesh via them. Since the broker is typically installed on other
distributions, the openwrt broker package has not received any
maintenance in recent years [0]. I  take now care of the further maintaince
of this package. Furthermore, I consulted with the maintainers to ensure
that they were comfortable with the change [1].

This PR is just a refactoring of the already existing opkg package from
wlanslovenija. It fixes config parsing and in general the config, adapts
to the new python syntax and fixes dependency handling.

- [0] https://github.com/wlanslovenija/firmware-packages-opkg/tree/master/net/tunneldigger-broker
- [1] https://github.com/wlanslovenija/firmware-packages-opkg/issues/24

Signed-off-by: Nick Hainke <vincent@systemli.org>

net/tunneldigger-broker/Makefile

@@ -0,0 +1,72 @@
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=tunneldigger-broker
+PKG_RELEASE:=1
+
+PKG_SOURCE_URL:=https://github.com/wlanslovenija/tunneldigger.git
+PKG_SOURCE_PROTO:=git
+PKG_SOURCE_VERSION:=4f72b30578ac3dbc5482f4a54054bf870355bdf5
+PKG_MIRROR_HASH:=e93b986b60475c16b0022ba4f5da981929cc3d6992c632f41264804912825473
+
+PKG_MAINTAINER:=Nick Hainke <vincent@systemli.org>
+PKG_LICENSE:=AGPL-3.0
+PKG_LICENSE_FILES:=COPYING
+
+PKG_BUILD_DEPENDS:=python-cffi/host
+
+include ../../lang/python/pypi.mk
+include $(INCLUDE_DIR)/package.mk
+include ../../lang/python/python3-package.mk
+
+define Package/tunneldigger-broker
+  SECTION:=net
+  CATEGORY:=Network
+  DEPENDS:= \
+	+ip-full \
+	+kmod-l2tp \
+	+kmod-l2tp-ip \
+	+kmod-l2tp-eth \
+	+kmod-sched \
+	+libnetfilter-conntrack \
+	+libnfnetlink \
+	+libnl-tiny \
+	+libpthread \
+	+librt \
+	+python3-cffi \
+	+python3-ctypes \
+	+python3-light \
+	+python3-logging \
+	+python3-six \
+	+tc-full
+  TITLE:=Broker for L2TPv3 tunnels using tunneldigger
+  URL:=https://github.com/wlanslovenija/tunneldigger
+endef
+
+define Package/tunneldigger-broker/description
+Tunneldigger is a simple VPN tunneling solution based on the Linux kernel
+support for L2TPv3 tunnels over UDP. This package contains the broker.
+endef
+
+PYTHON3_PKG_SETUP_DIR:=broker
+PYTHON3_PKG_WHEEL_VERSION:=0.4.0.dev1
+
+define Py3Package/tunneldigger-broker/install
+	$(INSTALL_DIR) $(1)/lib/functions
+	$(INSTALL_DATA) ./files/tunneldigger.sh $(1)/lib/functions/tunneldigger.sh
+	$(INSTALL_DIR) $(1)/usr/lib/tunneldigger-broker/hooks
+	$(INSTALL_BIN) ./files/hook-setup $(1)/usr/lib/tunneldigger-broker/hooks/setup
+	$(INSTALL_BIN) ./files/hook-teardown $(1)/usr/lib/tunneldigger-broker/hooks/teardown
+	$(INSTALL_BIN) ./files/hook-mtu-changed $(1)/usr/lib/tunneldigger-broker/hooks/mtu-changed
+	$(INSTALL_DIR) $(1)/etc/init.d
+	$(INSTALL_BIN) ./files/tunneldigger-broker.init $(1)/etc/init.d/tunneldigger-broker
+	$(INSTALL_DIR) $(1)/etc/config
+	$(INSTALL_DATA) ./files/config.default $(1)/etc/config/tunneldigger-broker
+endef
+
+define Package/tunneldigger-broker/conffiles
+/etc/config/tunneldigger-broker
+endef
+
+$(eval $(call Py3Package,tunneldigger-broker))
+$(eval $(call BuildPackage,tunneldigger-broker))
+$(eval $(call BuildPackage,tunneldigger-broker-src))

net/tunneldigger-broker/files/config.default

@@ -0,0 +1,18 @@
+config broker
+	list port '53'
+	list port '123'
+	list port '8942'
+	option interface 'loopback'
+	option max_cookies '1024'
+	option max_tunnels '1024'
+	option port_base '20000'
+	option tunnel_id_base '100'
+	option tunnel_timeout '60'
+	option pmtu '0'
+	option namespace 'production'
+	option connection_rate_limit '0.2'
+
+config log
+	option filename '/dev/null'
+	option verbosity 'INFO'
+	option log_ip_addresses '0'

net/tunneldigger-broker/files/hook-mtu-changed

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+. /lib/functions/tunneldigger.sh
+
+TUNNEL_ID="$1"
+INTERFACE="$3"
+OLD_MTU="$4"
+NEW_MTU="$5"
+
+# Get the bridge interface name for the old and new MTUs.
+tunneldigger_get_bridge old_bridge "${OLD_MTU}"
+tunneldigger_get_bridge new_bridge "${NEW_MTU}"
+
+if [ -z "$old_bridge" ]; then
+  echo "Unable to determine which bridge to use for MTU ${OLD_MTU}."
+  exit 1
+fi
+
+if [ -z "$new_bridge" ]; then
+  echo "Unable to determine which bridge to use for MTU ${NEW_MTU}."
+  exit 1
+fi
+
+# Remove interface from old bridge.
+ip link set dev ${INTERFACE} nomaster
+ip link set dev ${old_bridge} mtu ${OLD_MTU}
+
+# Change interface bridge and MTU.
+ip link set dev ${INTERFACE} master ${new_bridge} mtu ${NEW_MTU}
+ip link set dev ${new_bridge} mtu ${NEW_MTU}

net/tunneldigger-broker/files/hook-setup

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+. /lib/functions/tunneldigger.sh
+
+TUNNEL_ID="$1"
+INTERFACE="$3"
+MTU="$4"
+
+# Get the bridge interface name for this MTU.
+tunneldigger_get_bridge bridge "${MTU}"
+if [ -z "$bridge" ]; then
+  echo "Unable to determine which bridge to use for MTU ${MTU}."
+  exit 1
+fi
+
+# Disable IPv6 on this interface as it will be bridged.
+echo 1 > /proc/sys/net/ipv6/conf/${INTERFACE}/disable_ipv6
+# Add the interface to the proper bridge and bring it up.
+ip link set dev ${INTERFACE} master ${bridge} mtu ${MTU} up
+# Ensure bridge MTU.
+ip link set dev ${bridge} mtu ${MTU}

net/tunneldigger-broker/files/hook-teardown

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+TUNNEL_ID="$1"
+INTERFACE="$3"
+MTU="$4"
+
+# Remove interface from the bridge.
+ip link set dev ${INTERFACE} nomaster

net/tunneldigger-broker/files/tunneldigger-broker.init

@@ -0,0 +1,104 @@
+#!/bin/sh /etc/rc.common
+
+. $IPKG_INSTROOT/lib/functions/network.sh
+
+START=90
+USE_PROCD=1
+NAME=tunneldigger-broker
+
+PIDPATH=/var/run
+CONFIGFILE=/var/etc/tunneldigger-broker.cfg
+HOOKPATH=/usr/lib/tunneldigger-broker/hooks
+
+missing() {
+	echo "Not starting tunneldigger-broker - missing $1" >&2
+	exit 1
+}
+
+cfg_append() {
+	local value="$1"
+	echo "$value" >> $CONFIGFILE
+}
+
+cfg_append_section() {
+	local name="$1"
+	cfg_append "[${name}]"
+}
+
+cfg_append_kv() {
+	local key="$1"
+	local value="$2"
+	cfg_append "${key}=${value}"
+}
+
+cfg_append_option() {
+	local cfg="$1"
+	local option="$2"
+	local key="$3"
+	config_get value "$cfg" "${option}"
+	[ -z "${value}" ] && missing ${option}
+	cfg_append_kv "${key}" "${value}"
+}
+
+parse_broker() {
+	local section="$1"
+	cfg_append_section broker		
+	config_get interface "$section" interface
+
+	[ ! -z "${interface}" ] && {
+		# Resolve logical interface name.
+		unset _interface address
+		network_get_device _interface "${interface}" || _interface="${interface}"
+		cfg_append_kv interface "${_interface}"
+		network_get_ipaddr address "${interface}"
+		cfg_append_kv address "${address}"
+	}
+
+	OPTIONS="max_cookies max_tunnels port_base tunnel_id_base tunnel_timeout namespace connection_rate_limit pmtu"
+	for option in ${OPTIONS}; do
+		cfg_append_option "$section" "${option}" "${option}"
+	done
+
+	config_get port "$section" port
+	cfg_append_kv "port" "${port// /,}"
+
+	cfg_append_section hooks
+	cfg_append_kv "session.up" "${HOOKPATH}/setup"
+	cfg_append_kv "session.pre-down" "${HOOKPATH}/teardown"
+	cfg_append_kv "session.mtu-changed" "${HOOKPATH}/mtu-changed"
+}
+
+parse_log() {
+	local section="$1"
+	cfg_append_section log
+	
+	OPTIONS="filename verbosity"
+	for option in ${OPTIONS}; do
+		cfg_append_option "$section" "${option}" "${option}"
+	done
+
+	config_get_bool log_ip_addresses "$section" log_ip_addresses 1
+	if [ "${log_ip_addresses}" -eq 1 ]; then
+		cfg_append_kv "log_ip_addresses" "true"
+	else
+		cfg_append_kv "log_ip_addresses" "false"
+	fi
+}
+
+start_service() {
+	# Prepare the configuration file from UCI settings.
+	rm -f ${CONFIGFILE}
+	config_load tunneldigger-broker
+	config_foreach parse_broker broker
+	config_foreach parse_log log
+	
+	# Start the service using procd.
+	procd_open_instance
+	procd_set_param command "/usr/bin/python"
+	procd_append_param command -m tunneldigger_broker.main
+	procd_append_param command "${CONFIGFILE}"
+	procd_set_param respawn
+	procd_set_param stdout 1
+	procd_set_param stderr 1
+	procd_close_instance
+}

net/tunneldigger-broker/files/tunneldigger.sh

@@ -0,0 +1,39 @@
+. /lib/functions.sh
+. /lib/functions/network.sh
+
+tunneldigger_get_bridge() {
+	local variable="$1"
+	local mtu="$2"
+
+	# Overwrite the destination variable.
+	unset $variable
+	
+	# Discover the configured bridge.
+	unset _td_bridge
+	_td_bridge=""
+	config_cb() {
+		local cfg="$CONFIG_SECTION"
+		config_get configname "$cfg" TYPE
+		if [ "$configname" != "bridge" ]; then
+			return
+		fi
+
+		config_get cfg_mtu "$cfg" mtu
+		config_get interface "$cfg" interface
+		
+		if [ "$cfg_mtu" != "$mtu" ]; then
+			return
+		fi
+
+		_td_bridge="$interface"
+	}
+
+	config_load tunneldigger-broker
+	reset_cb
+	if [ -z "$_td_bridge" ]; then
+		return
+	fi
+
+	eval $variable=$_td_bridge
+	# network_get_device $variable $_td_bridge
+}