#!/bin/sh
# travelmate, a wlan connection manager for travel router
# written by Dirk Brenken (dev@brenken.org)

# This is free software, licensed under the GNU General Public License v3.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

# set initial defaults
#
LC_ALL=C
PATH="/usr/sbin:/usr/bin:/sbin:/bin"
trm_ver="1.3.1"
trm_sysver="unknown"
trm_enabled=0
trm_debug=0
trm_captive=1
trm_proactive=1
trm_captiveurl="http://captive.apple.com"
trm_minquality=35
trm_maxretry=3
trm_maxwait=30
trm_timeout=60
trm_radio=""
trm_connection=""
trm_rtfile="/tmp/trm_runtime.json"
trm_fetch="$(command -v uclient-fetch)"
trm_iwinfo="$(command -v iwinfo)"
trm_wpa="$(command -v wpa_supplicant)"
trm_action="${1:-"start"}"
trm_pidfile="/var/run/travelmate.pid"

# trim leading and trailing whitespace characters
#
f_trim()
{
	local trim="$1"

	trim="${trim#"${trim%%[![:space:]]*}"}"
	trim="${trim%"${trim##*[![:space:]]}"}"
	printf '%s' "${trim}"
}

# load travelmate environment
#
f_envload()
{
	local sys_call sys_desc sys_model sys_ver

	# get system information
	#
	sys_call="$(ubus -S call system board 2>/dev/null)"
	if [ -n "${sys_call}" ]
	then
		sys_desc="$(printf '%s' "${sys_call}" | jsonfilter -e '@.release.description')"
		sys_model="$(printf '%s' "${sys_call}" | jsonfilter -e '@.model')"
		trm_sysver="${sys_model}, ${sys_desc}"
	fi

	# (re-)initialize global list variables
	#
	unset trm_devlist trm_stalist trm_radiolist trm_active_sta

	# load config and check 'enabled' option
	#
	option_cb()
	{
		local option="${1}"
		local value="${2}"
		eval "${option}=\"${value}\""
	}
	config_load travelmate

	if [ ${trm_enabled} -ne 1 ]
	then
		f_log "info" "travelmate is currently disabled, please set 'trm_enabled' to '1' to use this service"
		exit 0
	fi

	# validate input ranges
	#
	if [ ${trm_minquality} -lt 20 ] || [ ${trm_minquality} -gt 80 ]
	then
		trm_minquality=35
	fi
	if [ ${trm_maxretry} -lt 1 ] || [ ${trm_maxretry} -gt 10 ]
	then
		trm_maxretry=3
	fi
	if [ ${trm_maxwait} -lt 20 ] || [ ${trm_maxwait} -gt 40 ] || [ ${trm_maxwait} -ge ${trm_timeout} ]
	then
		trm_maxwait=30
	fi
	if [ ${trm_timeout} -lt 30 ] || [ ${trm_timeout} -gt 300 ] || [ ${trm_timeout} -le ${trm_maxwait} ]
	then
		trm_timeout=60
	fi
}

# gather radio information & bring down all STA interfaces
#
f_prep()
{
	local eap_rc=0 config="${1}" proactive="${2}"
	local mode="$(uci_get wireless "${config}" mode)"
	local network="$(uci_get wireless "${config}" network)"
	local radio="$(uci_get wireless "${config}" device)"
	local disabled="$(uci_get wireless "${config}" disabled)"
	local eaptype="$(uci_get wireless "${config}" eap_type)"

	if [ -z "${trm_radio}" ] && [ -z "$(printf "%s" "${trm_radiolist}" | grep -Fo " ${radio}")" ]
	then
		trm_radiolist="$(f_trim "${trm_radiolist} ${radio}")"
	elif [ -n "${trm_radio}" ] && [ -z "${trm_radiolist}" ]
	then
		trm_radiolist="$(f_trim "$(printf "%s" "${trm_radio}" | \
			awk '{while(match(tolower($0),/radio[0-9]/)){ORS=" ";print substr(tolower($0),RSTART,RLENGTH);$0=substr($0,RSTART+RLENGTH)}}')")"
	fi
	if [ "${mode}" = "sta" ] && [ "${network}" = "${trm_iface}" ]
	then
		if ([ -z "${disabled}" ] || [ "${disabled}" = "0" ]) && ([ ${proactive} -eq 0 ] || [ "${trm_ifstatus}" != "true" ])
		then
			uci_set wireless "${config}" disabled 1
		elif [ "${disabled}" = "0" ] && [ "${trm_ifstatus}" = "true" ] && [ -z "${trm_active_sta}" ] && [ ${proactive} -eq 1 ]
		then
			trm_active_sta="${config}"
		fi
		if [ -n "${eaptype}" ]
		then
			eap_rc="$("${trm_wpa}" -veap >/dev/null 2>&1; printf "%u" ${?})"
		fi
		if [ -z "${eaptype}" ] || [ ${eap_rc} -eq 0 ]
		then
			trm_stalist="$(f_trim "${trm_stalist} ${config}_${radio}")"
		fi
	fi
	f_log "debug" "f_prep ::: config: ${config}, mode: ${mode}, network: ${network}, eap_rc: ${eap_rc}, radio: ${radio}, trm_radio: ${trm_radio:-"-"}, trm_active_sta: ${trm_active_sta:-"-"}, proactive: ${proactive}, disabled: ${disabled}"
}

# check interface status
#
f_check()
{
	local IFS ifname radio dev_status config sta_essid sta_bssid result wait=1 mode="${1}" status="${2:-"false"}"

	trm_ifquality=0
	if [ "${mode}" = "initial" ]
	then
		trm_ifstatus="false"
	else
		ubus call network reload
	fi
	while [ ${wait} -le ${trm_maxwait} ]
	do
		dev_status="$(ubus -S call network.wireless status 2>/dev/null)"
		if [ -n "${dev_status}" ]
		then
			if [ "${mode}" = "dev" ]
			then
				if [ "${trm_ifstatus}" != "${status}" ]
				then
					trm_ifstatus="${status}"
					f_jsnup
				fi
				for radio in ${trm_radiolist}
				do
					result="$(printf "%s" "${dev_status}" | jsonfilter -l1 -e "@.${radio}.up")"
					if [ "${result}" = "true" ] && [ -z "$(printf "%s" "${trm_devlist}" | grep -Fo " ${radio}")" ]
					then
						trm_devlist="$(f_trim "${trm_devlist} ${radio}")"
					fi
				done
				if [ "${trm_devlist}" = "${trm_radiolist}" ] || [ ${wait} -eq ${trm_maxwait} ]
				then
					ifname="${trm_devlist}"
					break
				else
					unset trm_devlist
				fi
			elif [ "${mode}" = "rev" ]
			then
				wait=$(( ${trm_maxwait} / 3 ))
				sleep ${wait}
				break
			else
				ifname="$(printf "%s" "${dev_status}" | jsonfilter -l1 -e '@.*.interfaces[@.config.mode="sta"].ifname')"
				if [ -n "${ifname}" ]
				then
					trm_ifquality="$(${trm_iwinfo} ${ifname} info 2>/dev/null | awk -F "[\/| ]" '/Link Quality:/{printf "%i\n", (100 / $NF * $(NF-1)) }')"
					if [ ${trm_ifquality} -ge ${trm_minquality} ]
					then
						trm_ifstatus="$(ubus -S call network.interface dump 2>/dev/null | jsonfilter -l1 -e "@.interface[@.device=\"${ifname}\"].up")"
					elif [ "${mode}" = "initial" ] && [ ${trm_ifquality} -lt ${trm_minquality} ]
					then
						trm_ifstatus="${status}"
						sta_essid="$(printf "%s" "${dev_status}" | jsonfilter -l1 -e '@.*.interfaces[@.config.mode="sta"].*.ssid')"
						sta_bssid="$(printf "%s" "${dev_status}" | jsonfilter -l1 -e '@.*.interfaces[@.config.mode="sta"].*.bssid')"
						f_log "info" "uplink '${sta_essid:-"-"}/${sta_bssid:-"-"}' is out of range (${trm_ifquality}/${trm_minquality}), uplink disconnected (${trm_sysver})"
					fi
				fi
			fi
			if [ "${mode}" = "initial" ] || [ "${trm_ifstatus}" = "true" ]
			then
				if ([ "${trm_ifstatus}" != "true" ] && [ "${trm_ifstatus}" != "${status}" ]) || \
					([ "${trm_ifstatus}" = "true" ] && [ "${mode}" = "sta" ] && [ -n "${trm_active_sta}" ]) || \
					[ ${trm_ifquality} -lt ${trm_minquality} ]
				then
					f_jsnup
				fi
				if [ "${mode}" = "initial" ] && [ ${trm_captive} -eq 1 ] && [ "${trm_ifstatus}" = "true" ]
				then
					result="$(${trm_fetch} --timeout=$(( ${trm_maxwait} / 3 )) "${trm_captiveurl}" -O /dev/null 2>&1 | \
						awk '/^Redirected/{printf "%s" "net cp \047"$NF"\047";exit}/^Download completed/{printf "%s" "net ok";exit}/^Failed|^Connection error/{printf "%s" "net nok";exit}')"
					if [ -n "${result}" ] && ([ -z "${trm_connection}" ] || [ "${result}" != "${trm_connection%/*}" ])
					then
						trm_connection="${result}/${trm_ifquality}"
						f_jsnup
					fi
				fi
				break
			fi
		fi
		wait=$(( wait + 1 ))
		sleep 1
	done
	f_log "debug" "f_check::: mode: ${mode}, name: ${ifname:-"-"}, status: ${trm_ifstatus}, quality: ${trm_ifquality}, result: ${result:-"-"}, connection: ${trm_connection:-"-"}, wait: ${wait}, max_wait: ${trm_maxwait}, min_quality: ${trm_minquality}, captive: ${trm_captive}"
}

# update runtime information
#
f_jsnup()
{
	local config sta_iface sta_radio sta_essid sta_bssid dev_status status="${trm_ifstatus}" faulty_list faulty_station="${1}"

	if [ "${status}" = "true" ]
	then
		status="connected (${trm_connection:-"-"})"
	else
		unset trm_connection
		status="running / not connected"
	fi

	dev_status="$(ubus -S call network.wireless status 2>/dev/null)"
	if [ -n "${dev_status}" ]
	then
		config="$(printf "%s" "${dev_status}" | jsonfilter -l1 -e '@.*.interfaces[@.config.mode="sta"].section')"
		if [ -n "${config}" ]
		then
			sta_iface="$(uci_get wireless "${config}" network)"
			sta_radio="$(uci_get wireless "${config}" device)"
			sta_essid="$(uci_get wireless "${config}" ssid)"
			sta_bssid="$(uci_get wireless "${config}" bssid)"
		fi
	fi

	json_get_var faulty_list "faulty_stations"
	if [ -n "${faulty_station}" ]
	then
		if [ -z "$(printf "%s" "${faulty_list}" | grep -Fo "${faulty_station}")" ]
		then
			faulty_list="$(f_trim "${faulty_list} ${faulty_station}")"
		fi
	fi
	json_add_string "travelmate_status" "${status}"
	json_add_string "travelmate_version" "${trm_ver}"
	json_add_string "station_id" "${sta_radio:-"-"}/${sta_essid:-"-"}/${sta_bssid:-"-"}"
	json_add_string "station_interface" "${sta_iface:-"-"}"
	json_add_string "faulty_stations" "${faulty_list}"
	json_add_string "last_rundate" "$(/bin/date "+%d.%m.%Y %H:%M:%S")"
	json_add_string "system" "${trm_sysver}"
	json_dump > "${trm_rtfile}"
	f_log "debug" "f_jsnup::: config: ${config:-"-"}, status: ${status:-"-"}, sta_iface: ${sta_iface:-"-"}, sta_radio: ${sta_radio:-"-"}, sta_essid: ${sta_essid:-"-"}, sta_bssid: ${sta_bssid:-"-"}, faulty_list: ${faulty_list:-"-"}"
}

# write to syslog
#
f_log()
{
	local class="${1}"
	local log_msg="${2}"

	if [ -n "${log_msg}" ] && ([ "${class}" != "debug" ] || [ ${trm_debug} -eq 1 ])
	then
		logger -p "${class}" -t "travelmate-${trm_ver}[${$}]" "${log_msg}"
		if [ "${class}" = "err" ]
		then
			trm_ifstatus="error"
			f_jsnup
			logger -p "${class}" -t "travelmate-${trm_ver}[${$}]" "Please check 'https://github.com/openwrt/packages/blob/master/net/travelmate/files/README.md' (${trm_sysver})"
			exit 1
		fi
	fi
}

# main function for connection handling
#
f_main()
{
	local IFS cnt dev config scan scan_list scan_essid scan_bssid scan_quality faulty_list
	local sta sta_essid sta_bssid sta_radio sta_iface active_essid active_bssid active_radio active_prio

	f_check "initial"
	if [ "${trm_ifstatus}" != "true" ] || [ ${trm_proactive} -eq 1 ]
	then
		config_load wireless
		config_foreach f_prep wifi-iface ${trm_proactive}
		if [ "${trm_ifstatus}" = "true" ] && [ ${trm_proactive} -eq 1 ]
		then
			json_get_var station_id "station_id"
			active_radio="${station_id%%/*}"
			active_essid="${station_id%/*}"
			active_essid="${active_essid#*/}"
			active_bssid="${station_id##*/}"
			f_check "dev" "true"
		else
			uci_commit wireless
			f_check "dev"
		fi
		json_get_var faulty_list "faulty_stations"
		f_log "debug" "f_main ::: iwinfo: ${trm_iwinfo:-"-"}, dev_list: ${trm_devlist:-"-"}, sta_list: ${trm_stalist:0:800}, faulty_list: ${faulty_list:-"-"}"
		for dev in ${trm_devlist}
		do
			f_log "debug" "f_main ::: dev: ${dev}"
			if [ -z "$(printf "%s" "${trm_stalist}" | grep -Fo "_${dev}")" ]
			then
				f_log "debug" "f_main ::: no station on '${dev}' - continue"
				continue
			fi
			cnt=1
			while [ ${cnt} -le ${trm_maxretry} ]
			do
				f_log "debug" "f_main ::: cnt: ${cnt}, max_cnt: ${trm_maxretry}"
				for sta in ${trm_stalist}
				do
					config="${sta%%_*}"
					sta_radio="${sta##*_}"
					sta_essid="$(uci_get wireless "${config}" ssid)"
					sta_bssid="$(uci_get wireless "${config}" bssid)"
					sta_iface="$(uci_get wireless "${config}" network)"
					json_get_var faulty_list "faulty_stations"
					if [ -n "$(printf "%s" "${faulty_list}" | grep -Fo "${sta_radio}/${sta_essid}/${sta_bssid}")" ]
					then
						f_log "debug" "f_main ::: faulty station '${sta_radio}/${sta_essid}/${sta_bssid:-"-"}' - continue"
						continue
					fi
					if ([ "${dev}" = "${active_radio}" ] && [ "${sta_essid}" = "${active_essid}" ] && [ "${sta_bssid:-"-"}" = "${active_bssid}" ]) || \
						([ "${dev}" != "${active_radio}" ] && [ "${active_prio}" = "true" ])
					then
						active_prio="true"
						f_log "debug" "f_main ::: active station prioritized '${active_radio}/${active_essid}/${active_bssid:-"-"}' - break"
						break
					fi
					if [ -z "${scan_list}" ]
					then
						scan_list="$(f_trim "$(${trm_iwinfo} "${dev}" scan 2>/dev/null | \
							awk 'BEGIN{FS="[/ ]"}/Address:/{var1=$NF}/ESSID:/{var2="";for(i=12;i<=NF;i++) \
							if(var2==""){var2=$i}else{var2=var2" "$i}}/Quality:/{printf "%i,%s,%s\n",(100/$NF*$(NF-1)),var1,var2}' | \
							sort -rn | awk '{ORS=",";print $0}')")"
						f_log "debug" "f_main ::: scan_list: ${scan_list:0:800}"
					fi
					IFS=","
					for scan in ${scan_list}
					do
						if [ -z "${scan_quality}" ]
						then
							scan_quality="${scan}"
						elif [ -z "${scan_bssid}" ]
						then
							scan_bssid="${scan}"
						elif [ -z "${scan_essid}" ]
						then
							scan_essid="${scan}"
						fi
						if [ -n "${scan_quality}" ] && [ -n "${scan_bssid}" ] && [ -n "${scan_essid}" ]
						then
							if [ ${scan_quality} -ge ${trm_minquality} ]
							then
								if (([ "${scan_essid}" = "\"${sta_essid}\"" ] && ([ -z "${sta_bssid}" ] || [ "${scan_bssid}" = "${sta_bssid}" ])) || \
									([ "${scan_bssid}" = "${sta_bssid}" ] && [ "${scan_essid}" = "unknown" ])) && [ "${dev}" = "${sta_radio}" ]
								then
									f_log "debug" "f_main ::: scan_quality: ${scan_quality}, sta_bssid: ${sta_bssid}, scan_bssid: ${scan_bssid}, sta_essid: \"${sta_essid}\", scan_essid: ${scan_essid}"
									if [ "${dev}" = "${active_radio}" ] && [ -n "${trm_active_sta}" ]
									then
										uci_set wireless "${trm_active_sta}" disabled 1
										unset trm_connection
									fi
									uci_set wireless "${config}" disabled 0
									f_check "sta"
									if [ "${trm_ifstatus}" = "true" ]
									then
										uci_commit wireless
										f_check "initial"
										f_log "info" "connected to uplink '${sta_radio}/${sta_essid}/${sta_bssid:-"-"}' (${trm_sysver})"
										return 0
									elif [ ${cnt} -eq ${trm_maxretry} ]
									then
										uci -q revert wireless
										f_check "rev"
										if [ "${dev}" = "${active_radio}" ] && [ -n "${trm_active_sta}" ]
										then
											f_check "initial"
										fi
										faulty_station="${sta_radio}/${sta_essid}/${sta_bssid:-"-"}"
										f_jsnup "${faulty_station}"
										f_log "info" "uplink disabled '${sta_radio}/${sta_essid}/${sta_bssid:-"-"}' (${trm_sysver})"
										break
									else
										uci -q revert wireless
										f_check "rev"
										f_jsnup
										f_log "info" "can't connect to uplink '${sta_radio}/${sta_essid}/${sta_bssid:-"-"}' (${trm_sysver})"
										unset scan_list
										break
									fi
								fi
							fi
							unset scan_quality scan_bssid scan_essid
						fi
					done
					unset IFS scan_quality scan_bssid scan_essid
				done
				cnt=$(( cnt + 1 ))
				sleep $(( ${trm_maxwait} / 6 ))
			done
			unset scan_list
		done
	fi
}

# source required system libraries
#
if [ -r "/lib/functions.sh" ] && [ -r "/usr/share/libubox/jshn.sh" ]
then
	. "/lib/functions.sh"
	. "/usr/share/libubox/jshn.sh"
else
	f_log "err" "system libraries not found"
fi

# initialize json runtime file
#
json_load_file "${trm_rtfile}" >/dev/null 2>&1
json_select data >/dev/null 2>&1
if [ ${?} -ne 0 ]
then
	> "${trm_rtfile}"
	json_init
	json_add_object "data"
fi

# control travelmate actions
#
while true
do
	if [ -z "${trm_action}" ]
	then
		sleep ${trm_timeout}
	elif [ "${trm_action}" = "stop" ]
	then
		> "${trm_rtfile}"
		f_log "info" "travelmate instance stopped ::: action: ${trm_action}, pid: $(cat ${trm_pidfile} 2>/dev/null)"
		exit 0
	else
		f_log "info" "travelmate instance started ::: action: ${trm_action}, pid: ${$}"
		unset trm_action
	fi
	f_envload
	f_main
done