Initial revision

Demo/sockets/gopher.py

+#! /usr/local/bin/python
+
+# A simple gopher client.
+#
+# Usage: gopher [ [selector] host [port] ]
+
+import string
+import sys
+import os
+import socket
+
+# Default selector, host and port
+DEF_SELECTOR = ''
+DEF_HOST     = 'gopher.micro.umn.edu'
+DEF_PORT     = 70
+
+# Recognized file types
+T_TEXTFILE  = '0'
+T_MENU      = '1'
+T_CSO       = '2'
+T_ERROR     = '3'
+T_BINHEX    = '4'
+T_DOS       = '5'
+T_UUENCODE  = '6'
+T_SEARCH    = '7'
+T_TELNET    = '8'
+T_BINARY    = '9'
+T_REDUNDANT = '+'
+T_SOUND     = 's'
+
+# Dictionary mapping types to strings
+typename = {'0': '<TEXT>', '1': '<DIR>', '2': '<CSO>', '3': '<ERROR>', \
+	'4': '<BINHEX>', '5': '<DOS>', '6': '<UUENCODE>', '7': '<SEARCH>', \
+	'8': '<TELNET>', '9': '<BINARY>', '+': '<REDUNDANT>', 's': '<SOUND>'}
+
+# Oft-used characters and strings
+CRLF = '\r\n'
+TAB = '\t'
+
+# Open a TCP connection to a given host and port
+def open_socket(host, port):
+	if type(port) == type(''):
+		port = string.atoi(port)
+	s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+	s.connect((host, port))
+	return s
+
+# Send a selector to a given host and port, return a file with the reply
+def send_request(selector, host, port):
+	s = open_socket(host, port)
+	s.send(selector + CRLF)
+	s.shutdown(1)
+	return s.makefile('r')
+
+# Get a menu in the form of a list of entries
+def get_menu(selector, host, port):
+	f = send_request(selector, host, port)
+	list = []
+	while 1:
+		line = f.readline()
+		if not line:
+			print '(Unexpected EOF from server)'
+			break
+		if line[-2:] == CRLF:
+			line = line[:-2]
+		elif line[-1:] in CRLF:
+			line = line[:-1]
+		if line == '.':
+			break
+		if not line:
+			print '(Empty line from server)'
+			continue
+		typechar = line[0]
+		parts = string.splitfields(line[1:], TAB)
+		if len(parts) < 4:
+			print '(Bad line from server:', `line`, ')'
+			continue
+		if len(parts) > 4:
+			print '(Extra info from server:', parts[4:], ')'
+		parts.insert(0, typechar)
+		list.append(parts)
+	f.close()
+	return list
+
+# Get a text file as a list of lines, with trailing CRLF stripped
+def get_textfile(selector, host, port):
+	list = []
+	get_alt_textfile(selector, host, port, list.append)
+	return list
+
+# Get a text file and pass each line to a function, with trailing CRLF stripped
+def get_alt_textfile(selector, host, port, func):
+	f = send_request(selector, host, port)
+	while 1:
+		line = f.readline()
+		if not line:
+			print '(Unexpected EOF from server)'
+			break
+		if line[-2:] == CRLF:
+			line = line[:-2]
+		elif line[-1:] in CRLF:
+			line = line[:-1]
+		if line == '.':
+			break
+		if line[:2] == '..':
+			line = line[1:]
+		func(line)
+	f.close()
+
+# Get a binary file as one solid data block
+def get_binary(selector, host, port):
+	f = send_request(selector, host, port)
+	data = f.read()
+	f.close()
+	return data
+
+# Get a binary file and pass each block to a function
+def get_alt_binary(selector, host, port, func, blocksize):
+	f = send_request(selector, host, port)
+	while 1:
+		data = f.read(blocksize)
+		if not data:
+			break
+		func(data)
+
+# A *very* simple interactive browser
+
+# Browser main command, has default arguments
+def browser(*args):
+	selector = DEF_SELECTOR
+	host = DEF_HOST
+	port = DEF_PORT
+	n = len(args)
+	if n > 0 and args[0]:
+		selector = args[0]
+	if n > 1 and args[1]:
+		host = args[1]
+	if n > 2 and args[2]:
+		port = args[2]
+	if n > 3:
+		raise RuntimeError, 'too many args'
+	try:
+		browse_menu(selector, host, port)
+	except socket.error, msg:
+		print 'Socket error:', msg
+		sys.exit(1)
+	except KeyboardInterrupt:
+		print '\n[Goodbye]'
+
+# Browse a menu
+def browse_menu(selector, host, port):
+	list = get_menu(selector, host, port)
+	while 1:
+		print '----- MENU -----'
+		print 'Selector:', `selector`
+		print 'Host:', host, ' Port:', port
+		print
+		for i in range(len(list)):
+			item = list[i]
+			typechar, description = item[0], item[1]
+			print string.rjust(`i+1`, 3) + ':', description,
+			if typename.has_key(typechar):
+				print typename[typechar]
+			else:
+				print '<TYPE=' + `typechar` + '>'
+		print
+		while 1:
+			try:
+				str = raw_input('Choice [CR == up a level]: ')
+			except EOFError:
+				print
+				return
+			if not str:
+				return
+			try:
+				choice = string.atoi(str)
+			except string.atoi_error:
+				print 'Choice must be a number; try again:'
+				continue
+			if not 0 < choice <= len(list):
+				print 'Choice out of range; try again:'
+				continue
+			break
+		item = list[choice-1]
+		typechar = item[0]
+		[i_selector, i_host, i_port] = item[2:5]
+		if typebrowser.has_key(typechar):
+			browserfunc = typebrowser[typechar]
+			try:
+				browserfunc(i_selector, i_host, i_port)
+			except (IOError, socket.error):
+				print '***', sys.exc_type, ':', sys.exc_value
+		else:
+			print 'Unsupported object type'
+
+# Browse a text file
+def browse_textfile(selector, host, port):
+	x = None
+	try:
+		p = os.popen('${PAGER-more}', 'w')
+		x = SaveLines().init(p)
+		get_alt_textfile(selector, host, port, x.writeln)
+	except IOError, msg:
+		print 'IOError:', msg
+	if x:
+		x.close()
+	f = open_savefile()
+	if not f:
+		return
+	x = SaveLines().init(f)
+	try:
+		get_alt_textfile(selector, host, port, x.writeln)
+		print 'Done.'
+	except IOError, msg:
+		print 'IOError:', msg
+	x.close()
+
+# Browse a search index
+def browse_search(selector, host, port):
+	while 1:
+		print '----- SEARCH -----'
+		print 'Selector:', `selector`
+		print 'Host:', host, ' Port:', port
+		print
+		try:
+			query = raw_input('Query [CR == up a level]: ')
+		except EOFError:
+			print
+			break
+		query = string.strip(query)
+		if not query:
+			break
+		if '\t' in query:
+			print 'Sorry, queries cannot contain tabs'
+			continue
+		browse_menu(selector + TAB + query, host, port)
+
+# "Browse" telnet-based information, i.e. open a telnet session
+def browse_telnet(selector, host, port):
+	if selector:
+		print 'Log in as', `selector`
+	if type(port) <> type(''):
+		port = `port`
+	sts = os.system('set -x; exec telnet ' + host + ' ' + port)
+	if sts:
+		print 'Exit status:', sts
+
+# "Browse" a binary file, i.e. save it to a file
+def browse_binary(selector, host, port):
+	f = open_savefile()
+	if not f:
+		return
+	x = SaveWithProgress().init(f)
+	get_alt_binary(selector, host, port, x.write, 8*1024)
+	x.close()
+
+# "Browse" a sound file, i.e. play it or save it
+def browse_sound(selector, host, port):
+	browse_binary(selector, host, port)
+
+# Dictionary mapping types to browser functions
+typebrowser = {'0': browse_textfile, '1': browse_menu, \
+	'4': browse_binary, '5': browse_binary, '6': browse_textfile, \
+	'7': browse_search, \
+	'8': browse_telnet, '9': browse_binary, 's': browse_sound}
+
+# Class used to save lines, appending a newline to each line
+class SaveLines:
+	def init(self, f):
+		self.f = f
+		return self
+	def writeln(self, line):
+		self.f.write(line + '\n')
+	def close(self):
+		sts = self.f.close()
+		if sts:
+			print 'Exit status:', sts
+
+# Class used to save data while showing progress
+class SaveWithProgress:
+	def init(self, f):
+		self.f = f
+		return self
+	def write(self, data):
+		sys.stdout.write('#')
+		sys.stdout.flush()
+		self.f.write(data)
+	def close(self):
+		print
+		sts = self.f.close()
+		if sts:
+			print 'Exit status:', sts
+
+# Ask for and open a save file, or return None if not to save
+def open_savefile():
+	try:
+		savefile = raw_input( \
+	    'Save as file [CR == don\'t save; |pipeline or ~user/... OK]: ')
+	except EOFError:
+		print
+		return None
+	savefile = string.strip(savefile)
+	if not savefile:
+		return None
+	if savefile[0] == '|':
+		cmd = string.strip(savefile[1:])
+		try:
+			p = os.popen(cmd, 'w')
+		except IOError, msg:
+			print `cmd`, ':', msg
+			return None
+		print 'Piping through', `cmd`, '...'
+		return p
+	if savefile[0] == '~':
+		savefile = os.path.expanduser(savefile)
+	try:
+		f = open(savefile, 'w')
+	except IOError, msg:
+		print `savefile`, ':', msg
+		return None
+	print 'Saving to', `savefile`, '...'
+	return f
+
+# Test program
+def test():
+	if sys.argv[4:]:
+		print 'usage: gopher [ [selector] host [port] ]'
+		sys.exit(2)
+	elif sys.argv[3:]:
+		browser(sys.argv[1], sys.argv[2], sys.argv[3])
+	elif sys.argv[2:]:
+		try:
+			port = string.atoi(sys.argv[2])
+			selector = ''
+			host = sys.argv[1]
+		except string.atoi_error:
+			selector = sys.argv[1]
+			host = sys.argv[2]
+			port = ''
+		browser(selector, host, port)
+	elif sys.argv[1:]:
+		browser('', sys.argv[1])
+	else:
+		browser()
+
+# Call the test program as a main program
+test()