nft-qos: add new package

This is the nftables implementation for qos on OpenWrt,
Currently, it has below features:

* Static QoS : setting limit rate for devices or global network.

* Dynamic/Auto QoS : setting limit rate according to the network
  bandwidth and adjust itself automatically (hotplug event).

* Traffic Priority : this feature is like traffic shaping under tc,
  it uses ingress hook to handle to packets here.

Signed-off-by: Rosy Song <rosysong@rosinson.com>

net/nft-qos/files/lib/dynamic.sh

@@ -0,0 +1,89 @@
+#!/bin/sh
+#
+# Copyright (C) 2018 rosysong@rosinson.com
+#
+
+. /lib/nft-qos/core.sh
+
+# return average rate for dhcp leases
+qosdef_dynamic_rate() { # <bandwidth>
+	local c=0 c6=0
+
+	[ ! -e /tmp/dhcp.leases -a \
+	  ! -e /var/dhcp6.leases ] && return
+
+	[ -e /tmp/dhcp.leases ] && \
+	  c=$(wc -l < /tmp/dhcp.leases 2>/dev/null)
+	[ -e /var/dhcp6.leases ] && \
+	  c6=$(wc -l < /var/dhcp6.leases 2>/dev/null)
+	[ $c -eq 0 -a $c6 -eq 0 ] && \
+	  { echo 12500; return; }
+
+	echo $(($1 / ($c + $c6)))
+}
+
+qosdef_append_chain_dym() { # <hook> <name> <bandwidth>
+	local cidr cidr6
+	local operator rate
+	local hook=$1 name=$2 bandwidth=$3
+
+	config_get cidr default 'dynamic_cidr'
+	config_get cidr6 default 'dynamic_cidr6'
+
+	[ -z "$cidr" -a -z "$cidr6" ] && return
+
+	case "$2" in
+		download) operator=daddr;;
+		upload) operator=saddr;;
+	esac
+
+	rate=$(qosdef_dynamic_rate $bandwidth)
+
+	qosdef_appendx "\tchain $name {\n"
+	qosdef_append_chain_def filter $hook 0 accept
+	qosdef_append_rule_limit_whitelist $name
+	[ -n "$cidr" ] && \
+		qosdef_append_rule_ip_limit $cidr $operator kbytes $rate
+	[ -n "$cidr6" ] && \
+		qosdef_append_rule_ip_limit $cidr6 $operator kbytes $rate
+	qosdef_appendx "\t}\n"
+}
+
+qosdef_flush_dynamic() {
+	qosdef_flush_table "$NFT_QOS_INET_FAMILY" nft-qos-dynamic
+}
+
+# init dynamic qos
+qosdef_init_dynamic() {
+	local dynamic_bw_up dynamic_bw_down limit_enable limit_type
+	local hook_ul="input" hook_dl="postrouting"
+
+	uci_validate_section nft-qos default default \
+		'limit_enable:bool:0' \
+		'limit_type:maxlength(8)' \
+		'dynamic_bw_up:uinteger:100' \
+		'dynamic_bw_down:uinteger:100'
+
+	[ $? -ne 0 ] && {
+		logger -t nft-qos-dynamic "validation failed"
+		return 1
+	}
+
+	[ $limit_enable -eq 0 -o \
+		"$limit_type" = "static" ] && return 1
+
+	# Transfer mbits/s to mbytes/s
+	# e.g. 100,000 kbits == 12,500 kbytes
+	dynamic_bw_up=$(($dynamic_bw_up * 1000 / 8))
+	dynamic_bw_down=$(($dynamic_bw_down * 1000 / 8))
+
+	[ -z "$NFT_QOS_HAS_BRIDGE" ] && {
+		hook_ul="postrouting"
+		hook_dl="input"
+	}
+
+	qosdef_appendx "table $NFT_QOS_INET_FAMILY nft-qos-dynamic {\n"
+	qosdef_append_chain_dym $hook_ul upload $dynamic_bw_up
+	qosdef_append_chain_dym $hook_dl download $dynamic_bw_down
+	qosdef_appendx "}\n"
+}