Demo/sockets/gopher.py

   1 #! /usr/bin/env python
   2
   3 # A simple gopher client.
   4 #
   5 # Usage: gopher [ [selector] host [port] ]
   6
   7 import sys
   8 import os
   9 import socket
  10
  11 # Default selector, host and port
  12 DEF_SELECTOR = ''
  13 DEF_HOST     = 'gopher.micro.umn.edu'
  14 DEF_PORT     = 70
  15
  16 # Recognized file types
  17 T_TEXTFILE  = '0'
  18 T_MENU      = '1'
  19 T_CSO       = '2'
  20 T_ERROR     = '3'
  21 T_BINHEX    = '4'
  22 T_DOS       = '5'
  23 T_UUENCODE  = '6'
  24 T_SEARCH    = '7'
  25 T_TELNET    = '8'
  26 T_BINARY    = '9'
  27 T_REDUNDANT = '+'
  28 T_SOUND     = 's'
  29
  30 # Dictionary mapping types to strings
  31 typename = {'0': '<TEXT>', '1': '<DIR>', '2': '<CSO>', '3': '<ERROR>', \
  32         '4': '<BINHEX>', '5': '<DOS>', '6': '<UUENCODE>', '7': '<SEARCH>', \
  33         '8': '<TELNET>', '9': '<BINARY>', '+': '<REDUNDANT>', 's': '<SOUND>'}
  34
  35 # Oft-used characters and strings
  36 CRLF = '\r\n'
  37 TAB = '\t'
  38
  39 # Open a TCP connection to a given host and port
  40 def open_socket(host, port):
  41     if not port:
  42         port = DEF_PORT
  43     elif type(port) == type(''):
  44         port = int(port)
  45     s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  46     s.connect((host, port))
  47     return s
  48
  49 # Send a selector to a given host and port, return a file with the reply
  50 def send_request(selector, host, port):
  51     s = open_socket(host, port)
  52     s.send(selector + CRLF)
  53     s.shutdown(1)
  54     return s.makefile('r')
  55
  56 # Get a menu in the form of a list of entries
  57 def get_menu(selector, host, port):
  58     f = send_request(selector, host, port)
  59     list = []
  60     while 1:
  61         line = f.readline()
  62         if not line:
  63             print('(Unexpected EOF from server)')
  64             break
  65         if line[-2:] == CRLF:
  66             line = line[:-2]
  67         elif line[-1:] in CRLF:
  68             line = line[:-1]
  69         if line == '.':
  70             break
  71         if not line:
  72             print('(Empty line from server)')
  73             continue
  74         typechar = line[0]
  75         parts = line[1:].split(TAB)
  76         if len(parts) < 4:
  77             print('(Bad line from server: %r)' % (line,))
  78             continue
  79         if len(parts) > 4:
  80             print('(Extra info from server: %r)' % (parts[4:],))
  81         parts.insert(0, typechar)
  82         list.append(parts)
  83     f.close()
  84     return list
  85
  86 # Get a text file as a list of lines, with trailing CRLF stripped
  87 def get_textfile(selector, host, port):
  88     list = []
  89     get_alt_textfile(selector, host, port, list.append)
  90     return list
  91
  92 # Get a text file and pass each line to a function, with trailing CRLF stripped
  93 def get_alt_textfile(selector, host, port, func):
  94     f = send_request(selector, host, port)
  95     while 1:
  96         line = f.readline()
  97         if not line:
  98             print('(Unexpected EOF from server)')
  99             break
 100         if line[-2:] == CRLF:
 101             line = line[:-2]
 102         elif line[-1:] in CRLF:
 103             line = line[:-1]
 104         if line == '.':
 105             break
 106         if line[:2] == '..':
 107             line = line[1:]
 108         func(line)
 109     f.close()
 110
 111 # Get a binary file as one solid data block
 112 def get_binary(selector, host, port):
 113     f = send_request(selector, host, port)
 114     data = f.read()
 115     f.close()
 116     return data
 117
 118 # Get a binary file and pass each block to a function
 119 def get_alt_binary(selector, host, port, func, blocksize):
 120     f = send_request(selector, host, port)
 121     while 1:
 122         data = f.read(blocksize)
 123         if not data:
 124             break
 125         func(data)
 126
 127 # A *very* simple interactive browser
 128
 129 # Browser main command, has default arguments
 130 def browser(*args):
 131     selector = DEF_SELECTOR
 132     host = DEF_HOST
 133     port = DEF_PORT
 134     n = len(args)
 135     if n > 0 and args[0]:
 136         selector = args[0]
 137     if n > 1 and args[1]:
 138         host = args[1]
 139     if n > 2 and args[2]:
 140         port = args[2]
 141     if n > 3:
 142         raise RuntimeError('too many args')
 143     try:
 144         browse_menu(selector, host, port)
 145     except socket.error as msg:
 146         print('Socket error:', msg)
 147         sys.exit(1)
 148     except KeyboardInterrupt:
 149         print('\n[Goodbye]')
 150
 151 # Browse a menu
 152 def browse_menu(selector, host, port):
 153     list = get_menu(selector, host, port)
 154     while 1:
 155         print('----- MENU -----')
 156         print('Selector:', repr(selector))
 157         print('Host:', host, ' Port:', port)
 158         print()
 159         for i in range(len(list)):
 160             item = list[i]
 161             typechar, description = item[0], item[1]
 162             print(repr(i+1).rjust(3) + ':', description, end=' ')
 163             if typechar in typename:
 164                 print(typename[typechar])
 165             else:
 166                 print('<TYPE=' + repr(typechar) + '>')
 167         print()
 168         while 1:
 169             try:
 170                 str = input('Choice [CR == up a level]: ')
 171             except EOFError:
 172                 print()
 173                 return
 174             if not str:
 175                 return
 176             try:
 177                 choice = int(str)
 178             except ValueError:
 179                 print('Choice must be a number; try again:')
 180                 continue
 181             if not 0 < choice <= len(list):
 182                 print('Choice out of range; try again:')
 183                 continue
 184             break
 185         item = list[choice-1]
 186         typechar = item[0]
 187         [i_selector, i_host, i_port] = item[2:5]
 188         if typechar in typebrowser:
 189             browserfunc = typebrowser[typechar]
 190             try:
 191                 browserfunc(i_selector, i_host, i_port)
 192             except (IOError, socket.error):
 193                 t, v, tb = sys.exc_info()
 194                 print('***', t, ':', v)
 195         else:
 196             print('Unsupported object type')
 197
 198 # Browse a text file
 199 def browse_textfile(selector, host, port):
 200     x = None
 201     try:
 202         p = os.popen('${PAGER-more}', 'w')
 203         x = SaveLines(p)
 204         get_alt_textfile(selector, host, port, x.writeln)
 205     except IOError as msg:
 206         print('IOError:', msg)
 207     if x:
 208         x.close()
 209     f = open_savefile()
 210     if not f:
 211         return
 212     x = SaveLines(f)
 213     try:
 214         get_alt_textfile(selector, host, port, x.writeln)
 215         print('Done.')
 216     except IOError as msg:
 217         print('IOError:', msg)
 218     x.close()
 219
 220 def raw_input(prompt):
 221     sys.stdout.write(prompt)
 222     sys.stdout.flush()
 223     return sys.stdin.readline()
 224
 225 # Browse a search index
 226 def browse_search(selector, host, port):
 227     while 1:
 228         print('----- SEARCH -----')
 229         print('Selector:', repr(selector))
 230         print('Host:', host, ' Port:', port)
 231         print()
 232         try:
 233             query = input('Query [CR == up a level]: ')
 234         except EOFError:
 235             print()
 236             break
 237         query = query.strip()
 238         if not query:
 239             break
 240         if '\t' in query:
 241             print('Sorry, queries cannot contain tabs')
 242             continue
 243         browse_menu(selector + TAB + query, host, port)
 244
 245 # "Browse" telnet-based information, i.e. open a telnet session
 246 def browse_telnet(selector, host, port):
 247     if selector:
 248         print('Log in as', repr(selector))
 249     if type(port) != type(''):
 250         port = repr(port)
 251     sts = os.system('set -x; exec telnet ' + host + ' ' + port)
 252     if sts:
 253         print('Exit status:', sts)
 254
 255 # "Browse" a binary file, i.e. save it to a file
 256 def browse_binary(selector, host, port):
 257     f = open_savefile()
 258     if not f:
 259         return
 260     x = SaveWithProgress(f)
 261     get_alt_binary(selector, host, port, x.write, 8*1024)
 262     x.close()
 263
 264 # "Browse" a sound file, i.e. play it or save it
 265 def browse_sound(selector, host, port):
 266     browse_binary(selector, host, port)
 267
 268 # Dictionary mapping types to browser functions
 269 typebrowser = {'0': browse_textfile, '1': browse_menu, \
 270         '4': browse_binary, '5': browse_binary, '6': browse_textfile, \
 271         '7': browse_search, \
 272         '8': browse_telnet, '9': browse_binary, 's': browse_sound}
 273
 274 # Class used to save lines, appending a newline to each line
 275 class SaveLines:
 276     def __init__(self, f):
 277         self.f = f
 278     def writeln(self, line):
 279         self.f.write(line + '\n')
 280     def close(self):
 281         sts = self.f.close()
 282         if sts:
 283             print('Exit status:', sts)
 284
 285 # Class used to save data while showing progress
 286 class SaveWithProgress:
 287     def __init__(self, f):
 288         self.f = f
 289     def write(self, data):
 290         sys.stdout.write('#')
 291         sys.stdout.flush()
 292         self.f.write(data)
 293     def close(self):
 294         print()
 295         sts = self.f.close()
 296         if sts:
 297             print('Exit status:', sts)
 298
 299 # Ask for and open a save file, or return None if not to save
 300 def open_savefile():
 301     try:
 302         savefile = input( \
 303     'Save as file [CR == don\'t save; |pipeline or ~user/... OK]: ')
 304     except EOFError:
 305         print()
 306         return None
 307     savefile = savefile.strip()
 308     if not savefile:
 309         return None
 310     if savefile[0] == '|':
 311         cmd = savefile[1:].strip()
 312         try:
 313             p = os.popen(cmd, 'w')
 314         except IOError as msg:
 315             print(repr(cmd), ':', msg)
 316             return None
 317         print('Piping through', repr(cmd), '...')
 318         return p
 319     if savefile[0] == '~':
 320         savefile = os.path.expanduser(savefile)
 321     try:
 322         f = open(savefile, 'w')
 323     except IOError as msg:
 324         print(repr(savefile), ':', msg)
 325         return None
 326     print('Saving to', repr(savefile), '...')
 327     return f
 328
 329 # Test program
 330 def test():
 331     if sys.argv[4:]:
 332         print('usage: gopher [ [selector] host [port] ]')
 333         sys.exit(2)
 334     elif sys.argv[3:]:
 335         browser(sys.argv[1], sys.argv[2], sys.argv[3])
 336     elif sys.argv[2:]:
 337         try:
 338             port = int(sys.argv[2])
 339             selector = ''
 340             host = sys.argv[1]
 341         except ValueError:
 342             selector = sys.argv[1]
 343             host = sys.argv[2]
 344             port = ''
 345         browser(selector, host, port)
 346     elif sys.argv[1:]:
 347         browser('', sys.argv[1])
 348     else:
 349         browser()
 350
 351 # Call the test program as a main program
 352 test()