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