bpfcountd: add initial package

bpfcountd was created to obtain packet statistics in larger networks
without stressing the cpu resources. bpfcountd will count the amount
of packages and bytes over time (for each defined rule). The rules
are defined using the tcpdump filter syntax (bpf). The collected
data is provided on a unix socket in plaintext.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>

net/bpfcountd/Makefile

@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: MIT
+# Copyright (C) 2022 Linus Lüssing <linus.luessing@c0d3.blue>
+
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=bpfcountd
+PKG_RELEASE:=1
+
+PKG_SOURCE_PROTO:=git
+PKG_SOURCE_DATE:=2021-06-26
+PKG_SOURCE_URL=https://github.com/lemoer/bpfcountd.git
+PKG_SOURCE_VERSION:=8b1aeb18d686815f93e2bfe976e536c5699d6371
+PKG_MIRROR_HASH:=e6e7adcc11c0fd33c6d3ac31423d3288812270944c2f31d9610ac8c3173a8c5f
+
+PKG_MAINTAINER:=Linus Lüssing <linus.luessing@c0d3.blue>
+PKG_LICENSE:=MIT
+PKG_LICENSE_FILES:=LICENSE
+
+include $(INCLUDE_DIR)/package.mk
+
+define Package/bpfcountd
+  SECTION:=net
+  CATEGORY:=Network
+  TITLE:=Berkeley Packet Filter Counting Daemon
+  DEPENDS:=+libpcap
+endef
+
+define Package/bpfcountd/description
+  bpfcountd was created to obtain packet statistics in larger networks
+  without stressing the cpu resources. bpfcountd will count the amount
+  of packages and bytes over time (for each defined rule). The rules
+  are defined using the tcpdump filter syntax (bpf). The collected
+  data is provided on a unix socket in plaintext.
+endef
+
+define Package/bpfcountd/install
+	$(INSTALL_DIR) $(1)/usr/sbin
+	$(INSTALL_BIN) $(PKG_BUILD_DIR)/bpfcountd $(1)/usr/sbin/
+	$(CP) ./files/* $(1)/
+endef
+
+$(eval $(call BuildPackage,bpfcountd))

net/bpfcountd/files/etc/bpfcountd.filters

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+arp;arp
+icmp6;icmp6

net/bpfcountd/files/etc/config/bpfcountd

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+config bpfcountd 'eth0_in'
+	option ifname 'eth0'
+	option prefilter 'inbound'
+	option filterfile '/etc/bpfcountd.filters'
+	option buffersize '2097152'
+	option disabled '1'
+
+config bpfcountd 'eth0_out'
+	option ifname 'eth0'
+	option prefilter 'outbound'
+	option filterfile '/etc/bpfcountd.filters'
+	option buffersize '2097152'
+	option disabled '1'

net/bpfcountd/files/etc/init.d/bpfcountd

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+#!/bin/sh /etc/rc.common
+# SPDX-License-Identifier: MIT
+# Copyright (C) 2022 Linus Lüssing <linus.luessing@c0d3.blue>
+
+USE_PROCD=1
+START=20
+STOP=90
+
+UNIXSOCKDIR=/var/run/bpfcountd
+
+bpfcountd_start() {
+	local cfg="$1"
+	local namespace="$2"
+	local disabled
+
+	local ifname
+	local prefilter
+	local filterfile
+	local buffersize
+
+	config_get_bool disabled "$cfg" disabled 0
+	[ "$disabled" -gt 0 ] && return 0
+
+	mkdir -p "$UNIXSOCKDIR"
+
+	config_get ifname "$cfg" "ifname"
+	config_get prefilter "$cfg" "prefilter"
+	config_get filterfile "$cfg" "filterfile"
+	config_get buffersize "$cfg" "buffersize"
+
+	[ -z "$ifname" ] && {
+		echo "Error: no ifname specified for $cfg" >&2
+		return 0
+	}
+	[ -z "$filterfile" ] && {
+		echo "Error: no filterfile specified for $cfg" >&2
+		return 0
+	}
+
+	[ -z "$namespace" ] && namespace="bpfcountd"
+
+	procd_open_instance "$namespace.$cfg"
+
+	procd_set_param command /usr/sbin/bpfcountd
+	procd_append_param command -i "$ifname"
+	procd_append_param command -f "$filterfile"
+	procd_append_param command -u $UNIXSOCKDIR/"$namespace.$cfg".sock
+	[ -n "$prefilter" ] && procd_append_param command -F "$prefilter"
+	[ -n "$buffersize" ] && procd_append_param command -b "$buffersize"
+
+	procd_set_param respawn ${respawn_threshold:-3600} ${respawn_timeout:-5} ${respawn_retry:-5}
+
+	procd_set_param stderr 1
+	procd_close_instance
+}
+
+start_service() {
+	local cfg="$1"
+	local namespace="$2"
+	local instance_found=0
+
+	. /lib/functions/network.sh
+
+	config_cb() {
+		local type="$1"
+		local name="$2"
+		if [ "$type" = "bpfcountd" ]; then
+			if [ -n "$cfg" -a "$cfg" = "$name" ]; then
+				instance_found=1
+			fi
+		fi
+	}
+
+	config_load bpfcountd
+
+	if [ -n "$cfg" ]; then
+		[ "$instance_found" -gt 0 ] || return
+		bpfcountd_start "$cfg" "$namespace"
+	else
+		config_foreach bpfcountd_start bpfcountd "$namespace"
+	fi
+}
+
+stop_service() {
+	local cfg="$1"
+	local namespace="$2"
+
+	[ -z "$namespace" ] && namespace="bpfcountd"
+
+	if [ -n "$cfg" ]; then
+		rm $UNIXSOCKDIR/$namespace.$cfg.sock
+	else
+		rm $UNIXSOCKDIR/$namespace.*.sock
+	fi
+}
+
+service_triggers() {
+	procd_add_reload_trigger bpfcountd
+}