enable-wifi-ap

#!/bin/bash
#
# Enable TinyPilot WiFi access point.

# Exit on first failure.
set -e

# Echo commands before executing them, by default to stderr.
set -x

# Exit on unset variable.
set -u

if (( "${EUID}" != 0 )); then
  >&2 echo 'This script requires root privileges.'
  >&2 echo 'Please re-run with sudo:'
  >&2 echo "  sudo $0 $*"
  >&2 exit 1
fi

NETWORK_NAME='TinyPilotWiFi'
NETWORK_COUNTRY='US'

print_help() {
  cat <<EOF
Usage: ${0##*/} [--help] [--password NETWORK_PASSWORD] [--ssid NETWORK_NAME] [--country NETWORK_COUNTRY]
Enable TinyPilot WiFi access point.
  --help                      Display this help and exit.
  --password NETWORK_PASSWORD The network password. Must be 8–63 characters in
                              length. If not specified, you will be prompted for
                              a password.
  --ssid NETWORK_NAME         Optional. The network name. Defaults to: ${NETWORK_NAME}
  --country NETWORK_COUNTRY   Optional. The network country in ISO 3166-1 alpha-2 format.
                              See https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
                              Defaults to: ${NETWORK_COUNTRY}

Note: Running this script will clear any potentially existing custom static IP
      configuration and also any potentially existing WiFi settings that might
      have been set up previously.

EOF
}

# Parse command-line arguments.
NETWORK_PASSWORD=''
while (( "$#" > 0 )); do
  case "$1" in
    --help)
      print_help
      exit
      ;;
    --password)
      if (( "$#" < 2 )); then
        shift;
        break;
      fi
      NETWORK_PASSWORD="$2"
      shift # For flag name.
      shift # For flag value.
      ;;
    --ssid)
      if (( "$#" < 2 )); then
        shift;
        break;
      fi
      NETWORK_NAME="$2"
      shift # For flag name.
      shift # For flag value.
      ;;
    --country)
      if (( "$#" < 2 )); then
        shift;
        break;
      fi
      NETWORK_COUNTRY="$2"
      shift # For flag name.
      shift # For flag value.
      ;;
    *)
      >&2 echo "Unknown agrument: $1"
      >&2 print_help
      exit 1
      ;;
  esac
done
readonly NETWORK_NAME
readonly NETWORK_COUNTRY

# Validate command-line arguments.
if [[ -z "${NETWORK_PASSWORD}" ]]; then
  read -r -s -p 'Set a WiFi password: ' NETWORK_PASSWORD
fi
readonly NETWORK_PASSWORD

if [[ -z "${NETWORK_PASSWORD}" ]] || \
  (( "${#NETWORK_PASSWORD}" < 8 )) || \
  (( "${#NETWORK_PASSWORD}" > 63 )); then
  >&2 echo 'The WiFi password must be 8–63 characters in length'
  >&2 print_help
  exit 1
fi

if [[ -z "${NETWORK_NAME}" ]]; then
  >&2 echo "The network name can't be empty"
  >&2 print_help
  exit 1
fi

if (( "${#NETWORK_COUNTRY}" != 2 )); then
  >&2 echo "Invalid network country: ${NETWORK_COUNTRY}"
  >&2 echo 'The country must be a 2 character country code (e.g., US)'
  >&2 print_help
  exit 1
fi

readonly NETWORK_AP_IP_ADDRESS='192.168.50.1'
readonly NETWORK_AP_CLIENT_IP_RANGE_START='192.168.50.2'
readonly NETWORK_AP_CLIENT_IP_RANGE_END='192.168.50.100'

apt install hostapd dnsmasq --yes

SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
readonly SCRIPT_DIR
# shellcheck source=lib/markers.sh
. "${SCRIPT_DIR}/lib/markers.sh"

# Clear existing TinyPilot network configurations.
"${SCRIPT_DIR}/strip-marker-sections" /etc/dhcpcd.conf

# Enable wireless network interface.
cat <<EOF | tee --append /etc/dhcpcd.conf
${MARKER_START}
interface wlan0
static ip_address=${NETWORK_AP_IP_ADDRESS}/24
nohook wpa_supplicant
${MARKER_END}
EOF

# Configure wireless access point.
cat <<EOF | tee /etc/hostapd/hostapd.conf
country_code=${NETWORK_COUNTRY}
interface=wlan0
ssid=${NETWORK_NAME}
hw_mode=g
channel=7
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=${NETWORK_PASSWORD}
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
EOF

# Configure DHCP server for wireless access point.
cat <<EOF | tee /etc/dnsmasq.conf
interface=wlan0
dhcp-range=${NETWORK_AP_CLIENT_IP_RANGE_START},${NETWORK_AP_CLIENT_IP_RANGE_END},255.255.255.0,24h
domain=wlan
address=/gw.wlan/${NETWORK_AP_IP_ADDRESS}
EOF

# Backup WPA configurations.
cp \
  --no-clobber \
  /etc/wpa_supplicant/wpa_supplicant.conf \
  /etc/wpa_supplicant/wpa_supplicant.conf.bak

if ! rfkill list wlan | grep -q 'yes'; then
  touch /etc/wpa_supplicant/wlan_enabled
fi

# Clear WPA configurations.
cat <<'EOF' | tee /etc/wpa_supplicant/wpa_supplicant.conf
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
EOF

# Start wireless access point.
rfkill unblock wlan
systemctl unmask hostapd dnsmasq
systemctl enable hostapd dnsmasq
systemctl restart hostapd dnsmasq

cat <<EOF
TinyPilot is now running a WiFi access point with the following details:
SSID: ${NETWORK_NAME}
Country: ${NETWORK_COUNTRY}
IP Address: ${NETWORK_AP_IP_ADDRESS}
IP Range: ${NETWORK_AP_CLIENT_IP_RANGE_START} - ${NETWORK_AP_CLIENT_IP_RANGE_END}
EOF