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         }
  31
  32         def __init__(self, sm):
  33                 self._sm = sm
  34                 # create socket
  35                 self._sock = socket.socket (socket.AF_UNIX, socket.SOCK_STREAM)
  36                 # delete old socket file and don't bitch around if it's not there
  37                 forcerm(socketname)
  38                 # bind socket to file name
  39                 self._sock.bind (socketname)
  40                 # allow only users in the tuergroup to write to the socket
  41                 os.chown (socketname, 0, tuergroupid)
  42                 os.chmod (socketname, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IWGRP)
  43                 # listen to the people, but not too many at once
  44                 self._sock.listen(1)
  45
  46         def _answer(self, conn):
  47                 def answer(msg):
  48                         # this is called in another thread, so it should be quick and not touch the TySocket
  49                         waynesend(conn, msg)
  50                         conn.close()
  51                 return answer
  52
  53         def accept(self):
  54                 '''Handles incoming connections and keyboard events'''
  55                 self._sock.settimeout(None)
  56                 while True:
  57                         # accept connections
  58                         conn, addr = self._sock.accept()
  59                         conn.settimeout(0.1)
  60                         try:
  61                                 # get peer information
  62                                 (pid, uid, gid) = struct.unpack('3i', conn.getsockopt(socket.SOL_SOCKET, SO_PEERCRED, struct.calcsize('3i')))
  63                                 # get some data from the client (enough to hold any valid command)
  64                                 data = conn.recv (32)
  65                                 # log the command
  66                                 logger.info("TySocket: Received command from %s (uid %d): %s" % (pwd.getpwuid(uid).pw_name, uid, str(data)))
  67                                 # lookup the command, send it to state machine
  68                                 if data in self.CMDs:
  69                                         self._sm.callback(self.CMDs[data], self._answer(conn))
  70                                         # _answer will be called, and it will close the connection
  71                                 else:
  72                                         waynesend(conn, 'Command not found')
  73                                         conn.close()
  74                         except KeyboardInterrupt:
  75                                 raise # forward Ctrl-C to the outside
  76                         except Exception as e:
  77                                 logger.critical("TySocket: Something went wrong: %s" % str(e))