generated from ztimson/template
Zakary Timson
8b7702e90c
All checks were successful
Code review / review (pull_request) Successful in 35s
581 lines
12 KiB
Bash
581 lines
12 KiB
Bash
#!/bin/bash
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set -e
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# Configuration =======================================================================================================
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#
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# Connection settings (SSID, passphrase, subnet, DHCP range, interface) can
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# be supplied three ways, highest priority first:
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# 1. Environment variables (FALLBACK_AP_*) - used for headless installs.
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# 2. The persisted config file below, written by `install`.
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# 3. The hard-coded defaults in this block.
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#
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# Everything else (timers, paths) is not meant to be reconfigured per-install
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# and stays as plain constants.
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CONFIG_FILE="/etc/fallback-ap.conf"
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if [ -f "$CONFIG_FILE" ]; then source "$CONFIG_FILE"; fi
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WLAN0_IFACE="${FALLBACK_AP_IFACE:-${SAVED_IFACE:-wlan0}}"
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AP_NAME="${FALLBACK_AP_SSID:-${SAVED_SSID:-$HOSTNAME}}"
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AP_PASSWORD="${FALLBACK_AP_PASSWORD:-${SAVED_PASSWORD:-guesswhatitis}}"
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AP_ENCRYPTION="${FALLBACK_AP_ENCRYPTION:-${SAVED_ENCRYPTION:-wpa-psk}}" # none | wpa-psk | sae
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FALLBACK_AP_CIDR="${FALLBACK_AP_CIDR:-${SAVED_CIDR:-10.10.10.1/24}}"
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FALLBACK_AP_DHCP_START_OCTET="${FALLBACK_AP_DHCP_START_OCTET:-${SAVED_DHCP_START_OCTET:-100}}"
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FALLBACK_AP_DHCP_END_OCTET="${FALLBACK_AP_DHCP_END_OCTET:-${SAVED_DHCP_END_OCTET:-250}}"
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AP_CIDR="$FALLBACK_AP_CIDR"
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AP_NETWORK_BASE="${AP_CIDR%%/*}" # e.g. "10.10.10.1" out of "10.10.10.1/24"
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AP_NETWORK_BASE="${AP_NETWORK_BASE%.*}" # e.g. "10.10.10"
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DHCP_START="${AP_NETWORK_BASE}.${FALLBACK_AP_DHCP_START_OCTET}"
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DHCP_END="${AP_NETWORK_BASE}.${FALLBACK_AP_DHCP_END_OCTET}"
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# How often, while the AP has no clients, to stop the AP and give
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# NetworkManager a chance to reconnect to a known Wi-Fi network.
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RECOVERY_CHECK_INTERVAL=60
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# How long to leave the AP down during a recovery attempt before giving
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# up and bringing the AP back.
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RECOVERY_WINDOW=20
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# Small delay after changing wlan0 state, to let things settle before
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# we query it again.
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STATE_SETTLE_DELAY=1
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CONNECTION_NAME="Fallback AP"
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SERVICE_NAME="fallback-ap"
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SERVICE_FILE="/etc/systemd/system/$SERVICE_NAME.service"
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STATE_DIR="/var/lib/fallback-ap"
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LAST_WIFI_FILE="$STATE_DIR/last-wifi"
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LOCK_FILE="$STATE_DIR/lock"
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STATE_FILE="$STATE_DIR/state"
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# End of Configuration ================================================================================================
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# Resolve the actual location of this script.
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SCRIPT_PATH="$(readlink -f "$0")"
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if [ -z "$SCRIPT_PATH" ] || [ ! -f "$SCRIPT_PATH" ]; then
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echo "Unable to determine script path."
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exit 1
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fi
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log() {
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echo "[$(date '+%H:%M:%S')] $*"
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}
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set_state() {
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printf '%s\n' "$1" > "$STATE_FILE"
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}
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get_state() {
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cat "$STATE_FILE" 2>/dev/null || echo "unknown"
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}
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is_ap_on() {
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nmcli -t -f NAME connection show --active 2>/dev/null |
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grep -Fxq "$CONNECTION_NAME"
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}
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is_wifi_connected() {
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nmcli -t -f DEVICE,TYPE,STATE,CONNECTION device status 2>/dev/null |
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awk -F: -v iface="$WLAN0_IFACE" -v ap="$CONNECTION_NAME" \
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'$1 == iface && $2 == "wifi" && $3 == "connected" && $4 != ap {found=1} END {exit !found}'
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}
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get_wifi_connection() {
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nmcli -t -f DEVICE,TYPE,STATE,CONNECTION device status 2>/dev/null |
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awk -F: -v iface="$WLAN0_IFACE" \
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'$1 == iface && $2 == "wifi" && $3 == "connected" {print $4; exit}'
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}
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remember_wifi() {
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local connection
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connection="$(get_wifi_connection)"
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[ -z "$connection" ] && return
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[ "$connection" = "$CONNECTION_NAME" ] && return
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mkdir -p "$STATE_DIR"
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if [ "$(cat "$LAST_WIFI_FILE" 2>/dev/null || true)" != "$connection" ]; then
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log "Remembering Wi-Fi connection: $connection"
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printf '%s\n' "$connection" > "$LAST_WIFI_FILE"
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fi
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}
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get_last_wifi() {
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[ -f "$LAST_WIFI_FILE" ] && cat "$LAST_WIFI_FILE"
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}
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get_client_count() {
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iw dev "$WLAN0_IFACE" station dump 2>/dev/null |
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grep -c '^Station ' || true
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}
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wait_for_ap_state() {
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local wanted="$1"
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local timeout="${2:-5}"
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for ((i=0; i<timeout*10; i++)); do
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if [ "$wanted" = "on" ] && is_ap_on; then
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return 0
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fi
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if [ "$wanted" = "off" ] && ! is_ap_on; then
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return 0
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fi
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sleep 0.1
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done
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return 1
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}
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wait_for_wifi() {
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local timeout="$1"
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for ((i=0; i<timeout*10; i++)); do
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if is_wifi_connected; then
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return 0
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fi
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sleep 0.1
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done
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return 1
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}
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start_ap() {
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if is_ap_on; then
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return 0
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fi
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log "Enabling AP: $AP_NAME"
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nmcli connection up "$CONNECTION_NAME" ifname "$WLAN0_IFACE" >/dev/null 2>&1 || {
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log "Failed to start AP"
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return 1
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}
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if ! wait_for_ap_state on 5; then
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log "AP failed to become active"
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return 1
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fi
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sleep "$STATE_SETTLE_DELAY"
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log "AP enabled"
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return 0
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}
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stop_ap() {
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if ! is_ap_on; then
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return 0
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fi
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log "Disabling AP"
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nmcli connection down "$CONNECTION_NAME" >/dev/null 2>&1 || true
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if ! wait_for_ap_state off 5; then
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log "AP failed to stop cleanly"
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return 1
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fi
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sleep "$STATE_SETTLE_DELAY"
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return 0
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}
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tick() {
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local now="$1"
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if is_wifi_connected; then
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remember_wifi
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if is_ap_on; then
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stop_ap
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fi
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set_state "wifi"
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last_attempt="$now"
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return
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fi
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if ! is_ap_on; then
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start_ap
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set_state "fallback"
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last_attempt="$now"
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return
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fi
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set_state "fallback"
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local clients
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clients="$(get_client_count)"
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if [ "$clients" -gt 0 ]; then
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last_attempt="$now"
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return
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fi
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if (( now - last_attempt >= RECOVERY_CHECK_INTERVAL )); then
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last_attempt="$now"
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attempt_recovery
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fi
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}
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attempt_recovery() {
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log "No AP clients, checking for known Wi-Fi (AP down for up to ${RECOVERY_WINDOW}s)"
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set_state "checking"
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stop_ap || true
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if is_ap_on; then
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log "AP did not go down, aborting recovery attempt"
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start_ap
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set_state "fallback"
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return 1
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fi
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if wait_for_wifi "$RECOVERY_WINDOW"; then
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sleep "$STATE_SETTLE_DELAY"
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if is_wifi_connected; then
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log "Wi-Fi reconnected"
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remember_wifi
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set_state "wifi"
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return 0
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fi
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fi
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log "No Wi-Fi available, restoring AP"
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start_ap
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set_state "fallback"
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return 1
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}
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save_config() {
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mkdir -p "$(dirname "$CONFIG_FILE")"
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cat > "$CONFIG_FILE" <<EOF
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SAVED_IFACE="$WLAN0_IFACE"
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SAVED_SSID="$AP_NAME"
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SAVED_PASSWORD="$AP_PASSWORD"
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SAVED_ENCRYPTION="$AP_ENCRYPTION"
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SAVED_CIDR="$FALLBACK_AP_CIDR"
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SAVED_DHCP_START_OCTET="$FALLBACK_AP_DHCP_START_OCTET"
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SAVED_DHCP_END_OCTET="$FALLBACK_AP_DHCP_END_OCTET"
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EOF
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chmod 600 "$CONFIG_FILE"
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}
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install() {
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if [ "$EUID" -ne 0 ]; then
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echo "Run this script as root."
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exit 1
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fi
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log "Installing NetworkManager fallback AP"
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apt-get update
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apt-get install -y network-manager iw
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systemctl enable NetworkManager
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systemctl start NetworkManager
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mkdir -p "$STATE_DIR"
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if is_wifi_connected; then
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remember_wifi
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fi
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create_connection
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save_config
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log "Creating recovery service"
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cat > "$SERVICE_FILE" <<EOF
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[Unit]
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Description=NetworkManager Fallback AP
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After=NetworkManager.service
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Wants=NetworkManager.service
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[Service]
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Type=simple
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ExecStart=$SCRIPT_PATH run
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Restart=always
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RestartSec=2
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[Install]
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WantedBy=multi-user.target
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EOF
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chmod 644 "$SERVICE_FILE"
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systemctl daemon-reload
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systemctl enable "$SERVICE_NAME"
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systemctl restart "$SERVICE_NAME"
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log "Installation complete"
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log "Script: $SCRIPT_PATH"
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log "Config file: $CONFIG_FILE"
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log "SSID: $AP_NAME"
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log "Interface: $WLAN0_IFACE"
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log "Network: $AP_CIDR"
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log "DHCP: $DHCP_START - $DHCP_END"
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log "Encryption: $AP_ENCRYPTION"
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log "Recovery check interval: ${RECOVERY_CHECK_INTERVAL}s"
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log "Recovery window: ${RECOVERY_WINDOW}s"
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log "Last Wi-Fi: $(get_last_wifi || echo none)"
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echo
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nmcli device status
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}
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create_connection() {
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log "Creating NetworkManager AP connection..."
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nmcli connection delete "$CONNECTION_NAME" >/dev/null 2>&1 || true
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nmcli connection add \
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type wifi \
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ifname "$WLAN0_IFACE" \
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con-name "$CONNECTION_NAME" \
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autoconnect no \
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ssid "$AP_NAME"
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nmcli connection modify "$CONNECTION_NAME" \
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connection.autoconnect no \
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connection.autoconnect-priority -999 \
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connection.autoconnect-retries 0 \
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802-11-wireless.mode ap \
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802-11-wireless.powersave 2 \
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ipv4.method shared \
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ipv4.addresses "$AP_CIDR" \
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ipv4.shared-dhcp-range "$DHCP_START,$DHCP_END" \
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ipv6.method disabled
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case "$AP_ENCRYPTION" in
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none)
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nmcli connection modify "$CONNECTION_NAME" \
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wifi-sec.key-mgmt none
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;;
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wpa-psk)
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if [ "${#AP_PASSWORD}" -lt 8 ] || [ "${#AP_PASSWORD}" -gt 63 ]; then
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echo "WPA-PSK password must be between 8 and 63 characters."
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exit 1
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fi
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nmcli connection modify "$CONNECTION_NAME" \
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wifi-sec.key-mgmt wpa-psk \
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wifi-sec.psk "$AP_PASSWORD"
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;;
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sae)
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if [ "${#AP_PASSWORD}" -lt 8 ]; then
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echo "WPA3-SAE password must be at least 8 characters."
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exit 1
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fi
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nmcli connection modify "$CONNECTION_NAME" \
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wifi-sec.key-mgmt sae \
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wifi-sec.psk "$AP_PASSWORD"
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;;
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*)
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echo "Unsupported encryption: $AP_ENCRYPTION"
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exit 1
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;;
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esac
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}
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uninstall() {
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if [ "$EUID" -ne 0 ]; then
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echo "Run this script as root."
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exit 1
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fi
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log "Uninstalling fallback AP"
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systemctl disable --now "$SERVICE_NAME" >/dev/null 2>&1 || true
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nmcli connection down "$CONNECTION_NAME" >/dev/null 2>&1 || true
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nmcli connection delete "$CONNECTION_NAME" >/dev/null 2>&1 || true
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rm -f "$SERVICE_FILE"
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rm -f "$CONFIG_FILE"
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rm -rf "$STATE_DIR"
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systemctl daemon-reload
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log "Fallback AP removed"
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}
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start() {
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mkdir -p "$STATE_DIR"
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(
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flock -n 9 || exit 1
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start_ap
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) 9>"$LOCK_FILE"
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}
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stop() {
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mkdir -p "$STATE_DIR"
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(
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flock -n 9 || exit 1
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stop_ap
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) 9>"$LOCK_FILE"
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}
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status() {
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echo
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echo "=== Service ==="
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systemctl status "$SERVICE_NAME" --no-pager || true
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echo
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echo "=== Devices ==="
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nmcli device status
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echo
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echo "=== Active Connections ==="
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nmcli connection show --active
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echo
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echo "=== Saved Wi-Fi Profiles ==="
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nmcli -f NAME,TYPE,AUTOCONNECT,AUTOCONNECT-PRIORITY connection show
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echo
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echo "=== Fallback AP ==="
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nmcli connection show "$CONNECTION_NAME" 2>/dev/null || echo "Not installed"
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echo
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echo "=== Config ($CONFIG_FILE) ==="
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echo "SSID: $AP_NAME"
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echo "Interface: $WLAN0_IFACE"
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echo "Network: $AP_CIDR"
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echo "DHCP: $DHCP_START - $DHCP_END"
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echo
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echo "=== Last Known Wi-Fi ==="
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get_last_wifi || echo "None"
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echo
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echo "=== State ==="
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get_state
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echo
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echo "=== AP Clients ==="
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get_client_count
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echo
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echo "=== Script ==="
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echo "$SCRIPT_PATH"
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}
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run() {
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local last_attempt=0
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local now
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mkdir -p "$STATE_DIR"
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log "Fallback AP service started"
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log "Script: $SCRIPT_PATH"
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exec 9>"$LOCK_FILE"
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flock 9
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if is_wifi_connected; then
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remember_wifi
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set_state "wifi"
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log "Wi-Fi already connected"
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else
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log "No Wi-Fi connection, starting fallback AP"
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start_ap
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set_state "fallback"
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fi
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flock -u 9
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while true; do
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now="$(date +%s)"
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|
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if flock -n 9; then
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tick "$now"
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flock -u 9
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fi
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sleep 1
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done
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}
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|
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if [ "$EUID" -ne 0 ]; then
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echo "Run this script as root."
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exit 1
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fi
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case "${1:-}" in
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install)
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install
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;;
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uninstall)
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uninstall
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;;
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start)
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start
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;;
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stop)
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stop
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;;
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status)
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status
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;;
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run)
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run
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;;
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*)
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echo "Usage: $SCRIPT_PATH {install|uninstall|start|stop|status|run}"
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exit 1
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;;
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esac |