tysock.py

   1 import socket, os, stat, struct, pwd, errno
   2 from statemachine import StateMachine
   3 from libtuer import logger
   4 SO_PEERCRED = 17 # DO - NOT - TOUCH
   5
   6 tuergroupid = 1005
   7 socketname = "/run/tuer.sock"
   8
   9 # send to client for information but don't care if it arrives
  10 def waynesend (conn, what):
  11         try:
  12                 conn.send(what.encode())
  13         except:
  14                 pass # we do not care
  15
  16 # delete a file, don't care if it did not exist in the first place
  17 def forcerm(name):
  18         try:
  19                 os.unlink (name)
  20         except OSError as e:
  21                 # only ignore error if it was "file didn't exist"
  22                 if e.errno != errno.ENOENT:
  23                         raise
  24
  25 # the class doing the actual work
  26 class TySocket():
  27         CMDs = {
  28                 b'buzz': StateMachine.CMD_BUZZ,
  29                 b'unlock': StateMachine.CMD_UNLOCK,
  30                 b'lock': StateMachine.CMD_LOCK,
  31                 b'fallback_mode_on': StateMachine.CMD_FALLBACK_ON,
  32                 b'fallback_mode_off': StateMachine.CMD_FALLBACK_OFF,
  33         }
  34
  35         def __init__(self, sm):
  36                 self._sm = sm
  37                 # create socket
  38                 self._sock = socket.socket (socket.AF_UNIX, socket.SOCK_STREAM)
  39                 # delete old socket file and don't bitch around if it's not there
  40                 forcerm(socketname)
  41                 # bind socket to file name
  42                 self._sock.bind (socketname)
  43                 # allow only users in the tuergroup to write to the socket
  44                 os.chown (socketname, 0, tuergroupid)
  45                 os.chmod (socketname, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IWGRP)
  46                 # listen to the people, but not too many at once
  47                 self._sock.listen(1)
  48
  49         def _answer(self, conn):
  50                 def answer(msg, lastMsg = True):
  51                         # this is called in another thread, so it should be quick and not touch the TySocket
  52                         waynesend(conn, msg)
  53                         if lastMsg:
  54                                 conn.close()
  55                 return answer
  56
  57         def accept(self):
  58                 '''Handles incoming connections and keyboard events'''
  59                 self._sock.settimeout(None)
  60                 while True:
  61                         # accept connections
  62                         conn, addr = self._sock.accept()
  63                         conn.settimeout(0.1)
  64                         try:
  65                                 # get peer information
  66                                 (pid, uid, gid) = struct.unpack('3i', conn.getsockopt(socket.SOL_SOCKET, SO_PEERCRED, struct.calcsize('3i')))
  67                                 # get some data from the client (enough to hold any valid command)
  68                                 data = conn.recv (32)
  69                                 # log the command
  70                                 logger.info("TySocket: Received command from %s (uid %d): %s" % (pwd.getpwuid(uid).pw_name, uid, str(data)))
  71                                 # lookup the command, send it to state machine
  72                                 if data in self.CMDs:
  73                                         self._sm.callback(self.CMDs[data], self._answer(conn))
  74                                         # _answer will be called, and it will close the connection
  75                                 else:
  76                                         waynesend(conn, 'Command not found')
  77                         except KeyboardInterrupt:
  78                                 raise # forward Ctrl-C to the outside
  79                         except socket.timeout:
  80                                 # it's okay
  81                                 logger.info("TySocket: Connection timed out")
  82                         except Exception as e:
  83                                 logger.critical("TySocket: Something went wrong: %s" % str(e))
  84                         conn.close()