sql-edition/servers/VendingMachine.py

   1 import re
   2 from CRC import do_crc
   3 from binascii import unhexlify
   4
   5 asynchronous_responses = [      '400', '401', # door open/closed
   6                                 '610',        # switches changed
   7                          ]
   8
   9 class VendingMachine:
  10         def __init__(self, rfh, wfh):
  11                 self.secret = 'AAAAAAAAAAAAAAAA'
  12                 self.rfh = rfh
  13                 self.wfh = wfh
  14                 self.challenge = None
  15                 # Initialise ourselves into a known state
  16                 self.wfh.write('\n')
  17                 self.await_prompt()
  18                 self.wfh.write('echo off\n')
  19                 self.await_prompt()
  20                 self.wfh.write('PING\n')
  21                 code = ''
  22                 while code != '000':
  23                         (code, _) = self.get_response()
  24
  25         def await_prompt(self):
  26                 self.wfh.flush()
  27                 state = 1
  28                 prefix = ''
  29                 s = ''
  30                 while True:
  31                         s = self.rfh.read(1)
  32                         if s == '': raise Exception
  33                         if s == '\n' or s == '\r':
  34                                 state = 1
  35                                 prefix = ''
  36                         if (s == '#' or s == '%') and state == 1: state = 2
  37                         if s == ' ' and state == 2:
  38                                 if prefix == '':
  39                                         self.challenge = None
  40                                         return
  41                                 if re.search('^[0-9a-fA-F]{4}$', prefix):
  42                                         self.challenge = unhexlify(prefix)
  43                                         return
  44
  45         def get_response(self):
  46                 self.wfh.flush()
  47                 while True:
  48                         s = ''
  49                         while s == '':
  50                                 s = self.rfh.readline()
  51                                 if s == '': return None
  52                                 s = s.strip('\r\n')
  53                         code = s[0:3]
  54                         text = s[4:]
  55                         if code in asynchronous_responses:
  56                                 self.handle_event(code, text)
  57                         else:
  58                                 self.await_prompt()
  59                                 return (code, text)
  60
  61         def handle_event(self, code, text):
  62                 pass
  63
  64         def authed_message(self, message):
  65                 if self.challenge == None:
  66                         return message
  67                 crc = do_crc('%c%c'%(self.challenge >> 8, self.challenge & 0xff))
  68                 crc = do_crc(self.secret, crc)
  69                 crc = do_crc(message, crc)
  70                 return message+'|'+('%04x'%crc)
  71
  72         def ping(self):
  73                 self.wfh.write('PING\n')
  74                 (code, string) = self.get_response()
  75                 return (code == '000', code, string)
  76
  77         def vend(self, item):
  78                 if not re.search('^[0-9][0-9]$', item):
  79                         return (False, 'Invalid item requested (%s)'%item)
  80                 self.wfh.write(self.authed_message(('V%s\n'%item)+'\n'))
  81                 (code, string) = self.get_response()
  82                 return (code, string)
  83
  84         def beep(self, duration = None, synchronous = True):
  85                 msg = 'B'
  86                 if synchronous: msg += 'S'
  87                 if duration != None:
  88                         if duration > 255: duration = 255
  89                         if duration < 1: duration = 1
  90                         msg += '%02x'%duration
  91                 self.wfh.write(msg+'\n')
  92                 (code, string) = self.get_response()
  93                 return (code == '500', code, string)
  94
  95         def silence(self, duration = None, synchronous = True):
  96                 msg = 'C'
  97                 if synchronous: msg += 'S'
  98                 if duration != None:
  99                         if duration > 255: duration = 255
 100                         if duration < 1: duration = 1
 101                         msg += '%02x'%duration
 102                 self.wfh.write(msg+'\n')
 103                 (code, string) = self.get_response()
 104                 # FIXME: workaround a bug in rom W. should be just: return (code == '500', code, string)
 105                 return (code == '500' or code == '501', code, string)
 106
 107         def display(self, string):
 108                 if len(string) > 10:
 109                         string = string[0:10]
 110                 self.wfh.write('D'+string+'\n')
 111                 (code, string) = self.get_response()
 112                 return (code == '300', code, string)
 113