udp-broadcast-relay-redux: Add package

This commit is largely based on the work from Daniel Dickinson in
PR #2096 which was never merged. I tweaked it in a number of ways.
All bugs with this package are mine, not his.

Signed-off-by: Aaron Curley <accwebs@gmail.com>

net/udp-broadcast-relay-redux-openwrt/Makefile

@@ -0,0 +1,49 @@
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=udp-broadcast-relay-redux
+PKG_RELEASE:=$(AUTORELEASE)
+PKG_LICENSE:=GPL-2.0
+
+PKG_SOURCE_PROTO:=git
+PKG_SOURCE_URL:=https://github.com/udp-redux/udp-broadcast-relay-redux
+PKG_SOURCE_DATE:=2021-04-05
+PKG_SOURCE_VERSION:=671372938b55a186625a80516f86e8b9948c977a
+PKG_MIRROR_HASH:=11cf8728f2b8e966f4f57032d817a889f680ed8e61afff35b52ca9c6789a03c6
+
+include $(INCLUDE_DIR)/package.mk
+
+define Package/udp-broadcast-relay-redux
+  SECTION:=net
+  CATEGORY:=Network
+  SUBMENU:=Routing and Redirection
+  TITLE:=listens for packets on a specified UDP broadcast port and replays them
+  URL:=https://github.com/udp-redux/udp-broadcast-relay-redux
+endef
+
+define Package/udp-broadcast-relay-redux/description
+	This program listens for packets on a specified UDP broadcast port.
+	When a packet is received, it sends that packet to all specified interfaces but
+	the one it came from as though it originated from the original sender.
+	The primary purpose of this is to allow games on machines on separated
+	local networks (Ethernet, WLAN) that use udp broadcasts to find each other to do so.
+	It also works on ppp links, so you can log in from windows boxes (e.g. using pptp)
+	and play LAN-based games together. Currently, you have to care about upcoming or
+	downgoing interfaces yourself.
+endef
+
+define Package/udp-broadcast-relay-redux/conffiles
+/etc/config/udp_broadcast_relay_redux
+endef
+
+define Build/Compile
+	$(TARGET_CC) $(TARGET_CFLAGS) $(PKG_BUILD_DIR)/main.c -o $(PKG_BUILD_DIR)/$(PKG_NAME)
+endef
+
+define Package/udp-broadcast-relay-redux/install
+	$(INSTALL_DIR) $(1)/usr/sbin $(1)/etc/config $(1)/etc/init.d
+	$(CP) $(PKG_BUILD_DIR)/$(PKG_NAME) $(1)/usr/sbin/
+	$(INSTALL_CONF) ./files/udp_broadcast_relay_redux.config $(1)/etc/config/udp_broadcast_relay_redux
+	$(INSTALL_BIN) ./files/udp-broadcast-relay-redux.init $(1)/etc/init.d/udp-broadcast-relay-redux
+endef
+
+$(eval $(call BuildPackage,udp-broadcast-relay-redux))

net/udp-broadcast-relay-redux-openwrt/files/udp-broadcast-relay-redux.init

@@ -0,0 +1,76 @@
+#!/bin/sh /etc/rc.common
+
+START=90
+STOP=10
+
+USE_PROCD=1
+PROG=/usr/sbin/udp-broadcast-relay-redux
+NAME=udp-broadcast-relay-redux
+PIDCOUNT=0
+
+validate_section_udp_broadcast_relay_redux()
+{
+    uci_validate_section udp_broadcast_relay_redux udp_broadcast_relay_redux "${1}" \
+	'id:uinteger' \
+	'port:port' \
+	'network:list(string)' \
+	'src_override:ip4addr' \
+	'dest_override:ip4addr'
+
+    [ -z "$id" ] && return 1
+
+    [ -z "$network" ] && return 1
+
+    [ -z "$port" ] && return 1
+
+    return 0
+}
+
+udp_broadcast_relay_redux_instance() {
+    local net network ifname id port src_override dest_override
+
+    validate_section_udp_broadcast_relay_redux "${1}" || {
+	echo "Validation failed"
+	return 1
+    }
+
+    PIDCOUNT="$((PIDCOUNT + 1))"
+
+    procd_open_instance
+    procd_set_param command "$PROG" "--id" "${id}" "--port" "${port}"
+
+    for net in $network; do
+	network_get_device ifname "$net"
+	if [ -z "$ifname" ]; then
+	    network_get_physdev ifname "$net"
+	fi
+	if [ -n "$ifname" ]; then
+	    procd_append_param command "--dev" "$ifname"
+	    procd_append_param netdev "$ifname"
+	fi
+    done
+
+    if [ -n "$src_override" ] ; then
+        procd_append_param command "-s" "$src_override"
+    fi
+
+    if [ -n "$dest_override" ] ; then
+        procd_append_param command "-t" "$dest_override"
+    fi
+
+    procd_add_jail ubr-${PIDCOUNT}
+    procd_close_instance
+}
+
+start_service() {
+    . /lib/functions.sh
+    . /lib/functions/network.sh
+
+    config_load udp_broadcast_relay_redux
+    config_foreach udp_broadcast_relay_redux_instance udp_broadcast_relay_redux
+}
+
+service_triggers() {
+    procd_add_reload_trigger "udp_broadcast_relay_redux"
+    procd_add_validation validate_section_udp_broadcast_relay_redux
+}

net/udp-broadcast-relay-redux-openwrt/files/udp_broadcast_relay_redux.config

@@ -0,0 +1,6 @@
+#config udp_broadcast_relay_redux
+#       option id 1
+#       option port 47624
+#       list network lan
+#       list network vpnsrv
+#       option dest_override 10.66.2.13