#!/bin/bash
################################################################################
# kiosk-wifi-helper-socket - socket front end for kiosk-wifi-helper.
#
# Run by systemd (kiosk-wifi-helper@.service, one instance per connection to
# /run/kiosk-wifi-helper.sock) as root, with the connection as stdin AND
# stdout. The kiosk app connects, sends
#
#     <action>\n<JSON request body>
#
# and half-closes; the reply is the helper's one JSON line.
#
# Why a socket and not `sudo`: the kiosk app can end up running with the
# Linux "no new privileges" flag, and sudo then refuses to run as root
# ("The 'no new privileges' flag is set"). A root service reached through a
# socket isn't affected by that flag. Who may connect is decided by the
# socket's owner/group/mode (root:kiosk 0660) - the same people who could
# run the helper through the old sudoers rule, no more.
#
# Only the fixed actions below are passed on; anything else is refused.
################################################################################
set -uo pipefail

HELPER="${KIOSK_WIFI_HELPER:-/usr/local/bin/kiosk-wifi-helper}"

# First line only; bash's read doesn't consume past the newline on a
# socket, so the JSON body stays on stdin for the helper.
IFS= read -r -t 10 -n 32 action || action=""

case "$action" in
    ifaces|status|scan|connect|region-status|region-set)
        exec "$HELPER" "$action"
        ;;
    *)
        echo '{"ok":false,"error":"unknown action"}'
        exit 1
        ;;
esac