support disallowing power requestsv2.1

1 files changed, 32 insertions, 5 deletions

diff --git a/src/app.py b/src/app.py
index b83666e..7533df7 100755
--- a/src/app.py
+++ b/src/app.py
@@ -40,12 +40,10 @@
 # no more.
 
 import abc
-import cgi
 from collections import namedtuple
 from concurrent.futures import ThreadPoolExecutor
 from enum import Enum
 from http import HTTPStatus
-import http.server
 import json
 import os
 import pwd
@@ -53,6 +51,8 @@ import shlex
 import socket
 import subprocess
 from subprocess import DEVNULL, PIPE, STDOUT
+import traceback
+import urllib.parse
 
 
 def split_by(xs, sep):
@@ -510,6 +510,17 @@ def systemd_users():
     return show_users(list_users())
 
 
+def cgi_one_value(params, name, default=None):
+    values = params.get(name, [])
+    if not values:
+        if default is None:
+            raise ValueError(f'must have at least one value: {name}')
+        return default
+    if len(values) > 1:
+        raise ValueError(f'multiple values are not supported: {name}')
+    return values[0]
+
+
 class Request(Enum):
     STATUS = 'status'
     TOP = 'top'
@@ -525,22 +536,38 @@ class Request(Enum):
             raise ValueError('HTTP path must start with a forward slash /')
         return Request(path[1:])
 
+    @staticmethod
+    def from_query_string(qs):
+        params = urllib.parse.parse_qs(qs, strict_parsing=True)
+        request = cgi_one_value(params, 'what')
+        request = Request(request)
+        request.disable_power = int(cgi_one_value(params, 'disable_power', '0'))
+        return request
+
     def process(self):
         if self is Request.STATUS:
             return Status().complete()
         if self is Request.TOP:
             return Top().complete()
+
+        if self in [Request.REBOOT, Request.POWEROFF] and self.disable_power:
+            return Response(None, HTTPStatus.FORBIDDEN)
         if self is Request.REBOOT:
             return Reboot().complete()
         if self is Request.POWEROFF:
             return Poweroff().complete()
+
         raise NotImplementedError(f'unknown request: {self}')
 
 
 def process_cgi_request():
-    params = cgi.FieldStorage()
-    what = params['what'].value
-    Request(what).process().write_as_cgi_script()
+    try:
+        request = Request.from_query_string(os.environ['QUERY_STRING'])
+        request.process().write_as_cgi_script()
+    except:
+        status = HTTPStatus.INTERNAL_SERVER_ERROR
+        response = Response(traceback.format_exc(), status)
+        response.write_as_cgi_script()
 
 
 def main():