hotspot.sh

#!/bin/bash
# DeskClock hotspot manager — runs as root via sudo
# Usage: hotspot.sh start  <iface> <ssid> <password>
#        hotspot.sh stop   <iface>
#        hotspot.sh status <iface>
#        hotspot.sh clients <iface>
#        hotspot.sh check
#        hotspot.sh list

AP_IP="192.168.4.1"
HOSTAPD_CONF="/tmp/deskclock_hostapd.conf"
DNSMASQ_CONF="/tmp/deskclock_dnsmasq.conf"

_pid_file()  { echo "/tmp/deskclock_hostapd_${1}.pid"; }
_dpid_file() { echo "/tmp/deskclock_dnsmasq_${1}.pid"; }

case "$1" in

  start)
    IFACE="$2"; SSID="$3"; PASS="$4"
    if [ -z "$IFACE" ] || [ -z "$SSID" ] || [ -z "$PASS" ]; then
      echo "ERROR: usage: start <iface> <ssid> <password>" >&2; exit 1
    fi
    HOSTAPD_PID=$(_pid_file "$IFACE")
    DNSMASQ_PID=$(_dpid_file "$IFACE")

    # Write hostapd config
    cat > "$HOSTAPD_CONF" <<HEOF
interface=$IFACE
driver=nl80211
ssid=$SSID
hw_mode=g
channel=6
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=$PASS
wpa_key_mgmt=WPA-PSK
rsn_pairwise=CCMP
HEOF

    # Write dnsmasq config
    cat > "$DNSMASQ_CONF" <<DEOF
interface=$IFACE
bind-interfaces
dhcp-range=192.168.4.2,192.168.4.20,12h
dhcp-option=3,$AP_IP
dhcp-option=6,8.8.8.8,8.8.4.4
DEOF

    # If using primary interface, stop wpa_supplicant client on it
    if [ "$IFACE" = "wlan0" ]; then
      wpa_cli -i "$IFACE" terminate 2>/dev/null || true
      sleep 1
    fi

    # Configure static IP
    ip addr flush dev "$IFACE" 2>/dev/null || true
    ip addr add "${AP_IP}/24" dev "$IFACE"
    ip link set "$IFACE" up

    # Start hostapd
    hostapd -B -P "$HOSTAPD_PID" "$HOSTAPD_CONF" 2>/tmp/hostapd_err.txt
    if [ $? -ne 0 ]; then
      echo "ERROR: hostapd failed — $(cat /tmp/hostapd_err.txt)" >&2; exit 1
    fi

    # Start dnsmasq (kill stale instance first)
    pkill -f "dnsmasq.*deskclock" 2>/dev/null || true
    sleep 0.3
    dnsmasq --conf-file="$DNSMASQ_CONF" --pid-file="$DNSMASQ_PID"

    echo "OK $AP_IP"
    ;;

  stop)
    IFACE="$2"
    if [ -z "$IFACE" ]; then echo "ERROR: iface required" >&2; exit 1; fi
    HOSTAPD_PID=$(_pid_file "$IFACE")
    DNSMASQ_PID=$(_dpid_file "$IFACE")

    # Kill hostapd
    if [ -f "$HOSTAPD_PID" ]; then
      kill "$(cat "$HOSTAPD_PID")" 2>/dev/null || true
      rm -f "$HOSTAPD_PID"
    fi
    pkill -f "hostapd.*deskclock" 2>/dev/null || true

    # Kill dnsmasq
    if [ -f "$DNSMASQ_PID" ]; then
      kill "$(cat "$DNSMASQ_PID")" 2>/dev/null || true
      rm -f "$DNSMASQ_PID"
    fi
    pkill -f "dnsmasq.*deskclock" 2>/dev/null || true

    sleep 0.5
    ip addr flush dev "$IFACE" 2>/dev/null || true

    # Resume WiFi client only if we took over the primary interface
    if [ "$IFACE" = "wlan0" ]; then
      systemctl restart wpa_supplicant 2>/dev/null || true
      sleep 2
      wpa_cli -i "$IFACE" reconfigure 2>/dev/null || true
    fi

    echo "OK stopped"
    ;;

  status)
    IFACE="$2"
    if [ -z "$IFACE" ]; then echo "inactive"; exit 0; fi
    HOSTAPD_PID=$(_pid_file "$IFACE")
    if [ -f "$HOSTAPD_PID" ] && kill -0 "$(cat "$HOSTAPD_PID")" 2>/dev/null; then
      echo "active $AP_IP"
    else
      echo "inactive"
    fi
    ;;

  clients)
    IFACE="$2"
    if [ -z "$IFACE" ]; then exit 0; fi
    iw dev "$IFACE" station dump 2>/dev/null \
      | awk '/^Station/{mac=$2} /signal:/{sig=$2} mac && sig{printf "%s %s dBm\n",mac,sig; mac=""; sig=""}'
    ;;

  check)
    MISSING=""
    command -v hostapd >/dev/null 2>&1 || MISSING="$MISSING hostapd"
    command -v dnsmasq >/dev/null 2>&1 || MISSING="$MISSING dnsmasq"
    if [ -n "$MISSING" ]; then echo "missing:$MISSING"; exit 1; fi
    echo "ok"
    ;;

  list)
    # Print available wlan interfaces and whether they are USB-attached
    for sysdir in /sys/class/net/wlan*; do
      [ -e "$sysdir" ] || continue
      iface=$(basename "$sysdir")
      subsys=$(readlink -f "$sysdir/device/subsystem" 2>/dev/null || echo "")
      if echo "$subsys" | grep -qi "usb"; then
        echo "$iface usb"
      else
        echo "$iface builtin"
      fi
    done
    ;;

  *)
    echo "Usage: $0 start <iface> <ssid> <pass> | stop <iface> | status <iface> | clients <iface> | check | list"
    exit 1
    ;;
esac