mirror of
https://github.com/python/cpython.git
synced 2025-11-04 07:31:38 +00:00
146 lines
3.5 KiB
Python
Executable file
146 lines
3.5 KiB
Python
Executable file
# A simple FTP client.
|
|
#
|
|
# The information to write this program was gathered from RFC 959,
|
|
# but this is not a complete implementation! Yet it shows how a simple
|
|
# FTP client can be built, and you are welcome to extend it to suit
|
|
# it to your needs...
|
|
#
|
|
# How it works (assuming you've read the RFC):
|
|
#
|
|
# User commands are passed uninterpreted to the server. However, the
|
|
# user never needs to send a PORT command. Rather, the client opens a
|
|
# port right away and sends the appropriate PORT command to the server.
|
|
# When a response code 150 is received, this port is used to receive
|
|
# the data (which is written to stdout in this version), and when the
|
|
# data is exhausted, a new port is opened and a corresponding PORT
|
|
# command sent. In order to avoid errors when reusing ports quickly
|
|
# (and because there is no s.getsockname() method in Python yet) we
|
|
# cycle through a number of ports in the 50000 range.
|
|
|
|
|
|
import sys, posix, string
|
|
from socket import *
|
|
|
|
|
|
BUFSIZE = 1024
|
|
|
|
# Default port numbers used by the FTP protocol.
|
|
#
|
|
FTP_PORT = 21
|
|
FTP_DATA_PORT = FTP_PORT - 1
|
|
|
|
# Change the data port to something not needing root permissions.
|
|
#
|
|
FTP_DATA_PORT = FTP_DATA_PORT + 50000
|
|
|
|
|
|
# Main program (called at the end of this file).
|
|
#
|
|
def main():
|
|
hostname = sys.argv[1]
|
|
control(hostname)
|
|
|
|
|
|
# Control process (user interface and user protocol interpreter).
|
|
#
|
|
def control(hostname):
|
|
#
|
|
# Create control connection
|
|
#
|
|
s = socket(AF_INET, SOCK_STREAM)
|
|
s.connect(hostname, FTP_PORT)
|
|
f = s.makefile('r') # Reading the replies is easier from a file...
|
|
#
|
|
# Control loop
|
|
#
|
|
r = None
|
|
while 1:
|
|
code = getreply(f)
|
|
if code in ('221', 'EOF'): break
|
|
if code == '150':
|
|
getdata(r)
|
|
code = getreply(f)
|
|
r = None
|
|
if not r:
|
|
r = newdataport(s, f)
|
|
cmd = getcommand()
|
|
if not cmd: break
|
|
s.send(cmd + '\r\n')
|
|
|
|
|
|
# Create a new data port and send a PORT command to the server for it.
|
|
# (Cycle through a number of ports to avoid problems with reusing
|
|
# a port within a short time.)
|
|
#
|
|
nextport = 0
|
|
#
|
|
def newdataport(s, f):
|
|
global nextport
|
|
port = nextport + FTP_DATA_PORT
|
|
nextport = (nextport+1) % 16
|
|
r = socket(AF_INET, SOCK_STREAM)
|
|
r.bind(gethostbyname(gethostname()), port)
|
|
r.listen(1)
|
|
sendportcmd(s, f, port)
|
|
return r
|
|
|
|
|
|
# Send an appropriate port command.
|
|
#
|
|
def sendportcmd(s, f, port):
|
|
hostname = gethostname()
|
|
hostaddr = gethostbyname(hostname)
|
|
hbytes = string.splitfields(hostaddr, '.')
|
|
pbytes = [`port/256`, `port%256`]
|
|
bytes = hbytes + pbytes
|
|
cmd = 'PORT ' + string.joinfields(bytes, ',')
|
|
s.send(cmd + '\r\n')
|
|
code = getreply(f)
|
|
|
|
|
|
# Process an ftp reply and return the 3-digit reply code (as a string).
|
|
# The reply should be a line of text starting with a 3-digit number.
|
|
# If the 4th char is '-', it is a multi-line reply and is
|
|
# terminate by a line starting with the same 3-digit number.
|
|
# Any text while receiving the reply is echoed to the file.
|
|
#
|
|
def getreply(f):
|
|
line = f.readline()
|
|
if not line: return 'EOF'
|
|
print line,
|
|
code = line[:3]
|
|
if line[3:4] == '-':
|
|
while 1:
|
|
line = f.readline()
|
|
if not line: break # Really an error
|
|
print line,
|
|
if line[:3] == code and line[3:4] != '-': break
|
|
return code
|
|
|
|
|
|
# Get the data from the data connection.
|
|
#
|
|
def getdata(r):
|
|
print '(accepting data connection)'
|
|
conn, host = r.accept()
|
|
print '(data connection accepted)'
|
|
while 1:
|
|
data = conn.recv(BUFSIZE)
|
|
if not data: break
|
|
sys.stdout.write(data)
|
|
print '(end of data connection)'
|
|
|
|
# Get a command from the user.
|
|
#
|
|
def getcommand():
|
|
try:
|
|
while 1:
|
|
line = raw_input('ftp.py> ')
|
|
if line: return line
|
|
except EOFError:
|
|
return ''
|
|
|
|
|
|
# Call the main program.
|
|
#
|
|
main()
|