From 73cd11d94370abeda8feca03852d80b55e649165 Mon Sep 17 00:00:00 2001
From: "Brian J. Tarricone" <brian@tarricone.org>
Date: Mon, 27 Jul 2020 03:41:20 -0700
Subject: [PATCH] Initial import

---
 install.sh          |   9 ++
 wan-failover        | 221 ++++++++++++++++++++++++++++++++++++++++++++
 wan-failover.config |  27 ++++++
 wan-failover.init.d |  31 +++++++
 4 files changed, 288 insertions(+)
 create mode 100755 install.sh
 create mode 100755 wan-failover
 create mode 100644 wan-failover.config
 create mode 100755 wan-failover.init.d

diff --git a/install.sh b/install.sh
new file mode 100755
index 0000000..76b7497
--- /dev/null
+++ b/install.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+mkdir -p /etc/config /etc/init.d /usr/sbin
+[ -f /etc/config/wan-failover ] || cp -a wan-failover.config /etc/config/wan-failover
+cp -a wan-failover.init.d /etc/init.d/wan-failover
+cp -a wan-failover /usr/sbin/wan-failover
+chmod +x /etc/init.d/wan-failover /usr/sbin/wan-failover
+ln -sf ../init.d/wan-failover /etc/rc.d/S99wan-failover
+ln -sf ../init.d/wan-failover /etc/rc.d/K85wan-failover
diff --git a/wan-failover b/wan-failover
new file mode 100755
index 0000000..fde9d1f
--- /dev/null
+++ b/wan-failover
@@ -0,0 +1,221 @@
+#!/bin/sh
+#
+# Copyright (c) Brian Tarricone <brian@tarricone.org>
+# Released under the terms of the BSD 3-clause license.
+# See https://opensource.org/licenses/BSD-3-Clause for details.
+
+set -e
+
+default_check_interval=5
+default_health_ips="8.8.8.8 1.1.1.1"
+default_ping_count=5
+default_health_quorum=1
+default_up_successes=5
+default_down_failures=3
+default_active_metric=10
+default_inactive_metric=20
+
+log() {
+    logger -t wan-failover -p daemon.notice "$1"
+}
+
+dlog() {
+    if [ "$debug" ]; then
+        logger -t wan-failover -p daemon.debug "$1"
+    fi
+}
+
+elog() {
+	logger -t wan-failover -p daemon.err "$1"
+}
+
+cfg() {
+    uci get "$1" 2>/dev/null
+}
+
+cfg_set() {
+    uci set "$1"="$2"
+}
+
+cfg_commit() {
+    uci commit "$1"
+}
+
+ourcfg() {
+    cfg "wan-failover.$1"
+}
+
+cfg_init() {
+    [ "$(ourcfg globals.debug || echo 'false')" = "true" ] && debug=1 || debug=
+	check_interval=$(ourcfg globals.check_interval || echo $default_check_interval)
+
+    primary_iface=$(ourcfg globals.primary || echo '')
+    primary_ifname=$(cfg network.$primary_iface.ifname || echo '')
+    fallback_iface=$(ourcfg globals.fallback || echo '')
+    fallback_ifname=$(cfg network.$fallback_iface.ifname || echo '')
+
+    primary_health_ips=$(ourcfg $primary_iface.ip || echo $default_health_ips)
+    primary_ping_count=$(ourcfg $primary_iface.count || echo $default_ping_count)
+    primary_health_quorum=$(ourcfg $primary_iface.quorum || echo $default_health_quorum)
+    primary_up_successes=$(ourcfg $primary_iface.up || echo $default_up_successes)
+    primary_down_failures=$(ourcfg $primary_iface.down || echo $default_down_failures)
+    
+    fallback_health_ips=$(ourcfg $fallback_iface.ip || echo $default_health_ips)
+    fallback_ping_count=$(ourcfg $fallback_iface.count || echo $default_ping_count)
+    fallback_health_quorum=$(ourcfg $fallback_iface.quorum || echo $default_health_quorum)
+    fallback_up_successes=$(ourcfg $fallback_iface.up || echo $default_up_successes)
+    fallback_down_failures=$(ourcfg $fallback_iface.down || echo $default_down_failures)
+
+    active_metric=$(ourcfg globals.active_metric || echo $default_active_metric)
+    inactive_metric=$(ourcfg globals.inactive_metric || echo $default_inactive_metric)
+
+    if [ -z "$primary_iface" ]; then
+    	elog "Must set wan-failover.globals.primary to the primary interface"
+    	exit 1
+	fi
+	if [ -z "$primary_ifname" ]; then
+		elog "Can't figure out interface device name for interface $primary_iface" >&2
+		exit 1
+	fi
+    if [ -z "$fallback_iface" ]; then
+    	elog "Must set wan-failover.globals.fallback to the fallback interface"
+    	exit 1
+	fi
+	if [ -z "$fallback_ifname" ]; then
+		elog "Can't figure out interface device name for interface $fallback_iface" >&2
+		exit 1
+	fi
+
+	log "initialized with primary interface $primary_iface ($primary_ifname), fallback interface $fallback_iface ($fallback_ifname); will wait $check_interval second(s) between each check"
+    log "will check primary using $primary_health_ips ($primary_health_quorum must work) with $primary_ping_count ping(s), and will require $primary_up_successes successes to be up, $primary_down_failures to be down"
+    log "will check fallback using $fallback_health_ips ($fallback_health_quorum must work) with $fallback_ping_count ping(s), and will require $fallback_up_successes successes to be up, $fallback_down_failures to be down"
+    log "active interface metric will be set to $active_metric, inactive to $inactive_metric"
+}
+
+get_active_iface() {
+    local primary=$(cfg network.$primary_iface.metric)
+    local fallback=$(cfg network.$fallback_iface.metric)
+    dlog "current primary metric is $primary, fallback metric is $fallback"
+    [ $primary -gt $fallback ] && echo $fallback_iface || echo $primary_iface
+}
+
+set_active_iface() {
+    local active=$1
+    local inactive=$2
+    dlog "setting interface $active active, $inactive inactive"
+    cfg_set network.$active.metric $active_metric
+    cfg_set network.$inactive.metric $inactive_metric
+    cfg_commit network
+    /etc/init.d/network reload
+}
+
+ping_target() {
+    local ifname=$1
+    local count=$2
+    local ip=$3
+
+    echo "$ip" | grep -q ':' && ping=ping6 || ping=ping
+
+    local successes=0
+    local failures=0
+    while [ $count -gt 0 ]; do
+        dlog "[$ifname,$ip] ping"
+        $ping -n -q -I $ifname -c 1 -w 2 $ip >/dev/null 2>&1 &&
+            successes=$(expr $successes + 1) ||
+            failures=$(expr $failures + 1)
+        dlog "[$ifname,$ip] ping successes: $successes, failures: $failures"
+        count=$(expr $count - 1 || true)
+    done
+
+    [ $successes -gt $failures ] && return 0 || return 1
+}
+
+check_health() {
+    local ifname=$1
+    shift
+    local count=$1
+    shift
+    local quorum=$1
+    shift
+    local ips="$@"
+
+    local pids=
+    local ip
+    for ip in $ips; do
+        ping_target $ifname $count $ip &
+        pids="$pids $!"
+    done
+
+    local successes=0
+    local failures=0
+    local pid
+    for pid in $pids; do
+        wait $pid && {
+        	dlog "[$pid] got success"
+            successes=$(expr $successes + 1)
+        } || {
+        	dlog "[$pid] got failure"
+            failures=$(expr $failures + 1)
+		}
+    done
+
+    [ $successes -ge $quorum ] && return 0 || return 1
+}
+
+cfg_init
+
+primary_successes=0
+primary_failures=0
+fallback_failures=0
+fallback_successes=0
+
+while true; do
+	sleep $check_interval
+
+    active=$(get_active_iface)
+    dlog "currently active: $active"
+
+    dlog "checking health"
+    check_health $primary_ifname $primary_ping_count $primary_health_quorum $primary_health_ips &
+    primary_pid=$!
+    check_health $fallback_ifname $fallback_ping_count $fallback_health_quorum $fallback_health_ips &
+    fallback_pid=$!
+
+    wait $primary_pid && {
+        primary_successes=$(expr $primary_successes + 1)
+        primary_failures=0
+    } || {
+        primary_successes=0
+        primary_failures=$(expr $primary_failures + 1)
+    }
+    dlog "[$primary_iface] health check done; successes: $primary_successes, failures: $primary_failures"
+
+    wait $fallback_pid && {
+        fallback_successes=$(expr $fallback_successes + 1)
+        fallback_failures=0
+    } || {
+        fallback_successes=0
+        fallback_failures=$(expr $fallback_failures + 1)
+    }
+    dlog "[$fallback_iface] health check done; successes: $fallback_successes, failures: $fallback_failures"
+
+    if [ "$active" = "$primary_iface" ]; then
+        if [ $primary_failures -ge $primary_down_failures ]; then
+            if [ $fallback_failures -ge $fallback_down_failures ]; then
+                elog "primary is down, but fallback is as well"
+            else
+                log "$primary_iface is down, setting $fallback_iface active"
+                set_active_iface $fallback_iface $primary_iface
+            fi
+        fi
+    else
+        if [ $primary_successes -ge $primary_up_successes ]; then
+            log "$primary_iface is back up; setting active"
+            set_active_iface $primary_iface $fallback_iface
+		elif [ $primary_successes -gt 0 ]; then
+			dlog "$primary_iface is coming back up; sticking with $fallback_iface until certain"
+        else
+            dlog "$primary_iface is still down; sticking with $fallback_iface"
+        fi
+    fi
+done
diff --git a/wan-failover.config b/wan-failover.config
new file mode 100644
index 0000000..3f4f172
--- /dev/null
+++ b/wan-failover.config
@@ -0,0 +1,27 @@
+config globals 'globals'
+	option primary 'wan'
+	option fallback 'wwan'
+	option check_interval 10
+	option debug 'false'
+
+config interface 'wan'
+	list ip '8.8.8.8'
+	list ip '1.1.1.1'
+	list ip '2001:4860:4860::8888'
+	list ip '2606:4700:4700::1112'
+	option quorum '2'
+	option count '5'
+	option timeout '2'
+	option down '3'
+	option up '5'
+
+config interface 'wwan'
+	list ip '8.8.8.8'
+	list ip '1.1.1.1'
+#	list ip '2001:4860:4860::8888'
+#	list ip '2606:4700:4700::1112'
+	option quorum '2'
+	option count '5'
+	option timeout '2'
+	option down '3'
+	option up '5'
diff --git a/wan-failover.init.d b/wan-failover.init.d
new file mode 100755
index 0000000..ce12e86
--- /dev/null
+++ b/wan-failover.init.d
@@ -0,0 +1,31 @@
+#!/bin/sh /etc/rc.common
+#
+# Copyright (c) Brian Tarricone <brian@tarricone.org>
+# Released under the terms of the BSD 3-clause license.
+# See https://opensource.org/licenses/BSD-3-Clause for details.
+
+START=99
+
+USE_PROCD=1
+PROG=/usr/sbin/wan-failover
+
+reload_service() {
+	json_init
+	json_add_array interfaces
+	for i in $(load_ifaces); do
+		json_add_string "" "$i"
+	done
+	json_close_array
+
+	ubus call umdns set_config "$(json_dump)"
+}
+
+start_service() {
+	procd_open_instance
+	procd_set_param command "$PROG"
+	procd_set_param respawn
+	procd_open_trigger
+	procd_add_config_trigger "config.change" "wan-failover" /etc/init.d/wan-failover restart
+	procd_close_trigger
+	procd_close_instance
+}