More than 400 lines of Python code implement an FTP server

Python version
Implemented more than the previous XXFTP more complete functions
1. Continue to support multiple users
2. Continue to support virtual directories
3. Added permission Settings to support user root and map virtual directories
4. Increase support for limiting the size of a user's root or virtual directory

The characteristics of XXFTP
1. Open source and cross-platform
2. Simple and easy to use
3. No database is needed
4. Super scalability
5. You can use XXFTP as your own private FTP server for free

Address of the test
ftp://xiaoxia.org
Anonymous account can be used!
Anonymous root directory read-only, maps to a virtual directory, can upload files but do not allow changes!

Method of use
Same as the previous use of XXFTP written in C language:

Create a root directory to hold the user directories.
Configure it in the config. XML.
Create user directories under the root directory.
If you want to specify a password, create a directory named ".xxftp",
Under which create a text file named "password" containing the MD5
The code of the password.
If you want to specify the welcome and goodbye message, write it in
Goodbye under the root directory.
4. The Configure config. XML.

The structure of your FTP server root may be like:

- / root
- XXFTP. Welcome
- XXFTP. Goodbye

- user1
-. XXFTP
- the password
-...
- user2
-. XXFTP
- the password
-...
- anonymous source code

 

import socket, threading, os, sys, time 
import hashlib, platform, stat 

listen_ip = "localhost" 
listen_port = 21 
conn_list = [] 
root_dir = "./home" 
max_connections = 500 
conn_timeout = 120 

class FtpConnection(threading.Thread): 
def __init__(self, fd): 
threading.Thread.__init__(self) 
self.fd = fd 
self.running = True 
self.setDaemon(True) 
self.alive_time = time.time() 
self.option_utf8 = False 
self.identified = False 
self.option_pasv = True 
self.username = "" 
def process(self, cmd, arg): 
cmd = cmd.upper(); 
if self.option_utf8: 
arg = unicode(arg, "utf8").encode(sys.getfilesystemencoding()) 
print "<<", cmd, arg, self.fd 
# Ftp Command 
if cmd == "BYE" or cmd == "QUIT": 
if os.path.exists(root_dir + "/xxftp.goodbye"): 
self.message(221, open(root_dir + "/xxftp.goodbye").read()) 
else: 
self.message(221, "Bye!") 
self.running = False 
return 
elif cmd == "USER": 
# Set Anonymous User 
if arg == "": arg = "anonymous" 
for c in arg: 
if not c.isalpha() and not c.isdigit() and c!="_": 
self.message(530, "Incorrect username.") 
return 
self.username = arg 
self.home_dir = root_dir + "/" + self.username 
self.curr_dir = "/" 
self.curr_dir, self.full_path, permission, self.vdir_list,  
limit_size, is_virtual = self.parse_path("/") 
if not os.path.isdir(self.home_dir): 
self.message(530, "User " + self.username + " not exists.") 
return 
self.pass_path = self.home_dir + "/.xxftp/password" 
if os.path.isfile(self.pass_path): 
self.message(331, "Password required for " + self.username) 
else: 
self.message(230, "Identified!") 
self.identified = True 
return 
elif cmd == "PASS": 
if open(self.pass_path).read() == hashlib.md5(arg).hexdigest(): 
self.message(230, "Identified!") 
self.identified = True 
else: 
self.message(530, "Not identified!") 
self.identified = False 
return 
elif not self.identified: 
self.message(530, "Please login with USER and PASS.") 
return 

self.alive_time = time.time() 
finish = True 
if cmd == "NOOP": 
self.message(200, "ok") 
elif cmd == "TYPE": 
self.message(200, "ok") 
elif cmd == "SYST": 
self.message(200, "UNIX") 
elif cmd == "EPSV" or cmd == "PASV": 
self.option_pasv = True 
try: 
self.data_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
self.data_fd.bind((listen_ip, 0)) 
self.data_fd.listen(1) 
ip, port = self.data_fd.getsockname() 
if cmd == "EPSV": 
self.message(229, "Entering Extended Passive Mode (|||" + str(port) + "|)") 
else: 
ipnum = socket.inet_aton(ip) 
self.message(227, "Entering Passive Mode (%s,%u,%u)." % 
(",".join(ip.split(".")), (port>>8&0xff), (port&0xff))) 
except: 
self.message(500, "failed to create data socket.") 
elif cmd == "EPRT": 
self.message(500, "implement EPRT later...") 
elif cmd == "PORT": 
self.option_pasv = False 
self.data_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
s = arg.split(",") 
self.data_ip = ".".join(s[:4]) 
self.data_port = int(s[4])*256 + int(s[5]) 
self.message(200, "ok") 
elif cmd == "PWD" or cmd == "XPWD": 
if self.curr_dir == "": self.curr_dir = "/" 
self.message(257, '"' + self.curr_dir + '"') 
elif cmd == "LIST" or cmd == "NLST": 
if arg != "" and arg[0] == "-": arg = "" # omit parameters 
remote, local, perm, vdir_list, limit_size, is_virtual = self.parse_path(arg) 
if not os.path.exists(local): 
self.message(550, "failed.") 
return 
if not self.establish(): return 
self.message(150, "ok") 
for v in vdir_list: 
f = v[0] 
if self.option_utf8: 
f = unicode(f, sys.getfilesystemencoding()).encode("utf8") 
if cmd == "NLST": 
info = f + "rn" 
else: 
info = "d%s%s------- %04u %8s %8s %8lu %s %srn" % ( 
"r" if "read" in perm else "-", 
"w" if "write" in perm else "-", 
1, "0", "0", 0, 
time.strftime("%b %d %Y", time.localtime(time.time())), 
f) 
self.data_fd.send(info) 
for f in os.listdir(local): 
if f[0] == ".": continue 
path = local + "/" + f 
if self.option_utf8: 
f = unicode(f, sys.getfilesystemencoding()).encode("utf8") 
if cmd == "NLST": 
info = f + "rn" 
else: 
st = os.stat(path) 
info = "%s%s%s------- %04u %8s %8s %8lu %s %srn" % ( 
"-" if os.path.isfile(path) else "d", 
"r" if "read" in perm else "-", 
"w" if "write" in perm else "-", 
1, "0", "0", st[stat.ST_SIZE], 
time.strftime("%b %d %Y", time.localtime(st[stat.ST_MTIME])), 
f) 
self.data_fd.send(info) 
self.message(226, "Limit size: " + str(limit_size)) 
self.data_fd.close() 
self.data_fd = 0 
elif cmd == "REST": 
self.file_pos = int(arg) 
self.message(250, "ok") 
elif cmd == "FEAT": 
features = "211-Features:rnSITESrnEPRTrnEPSVrnMDTMrnPASVrn" 
"REST STREAMrnSIZErnUTF8rn211 Endrn" 
self.fd.send(features) 
elif cmd == "OPTS": 
arg = arg.upper() 
if arg == "UTF8 ON": 
self.option_utf8 = True 
self.message(200, "ok") 
elif arg == "UTF8 OFF": 
self.option_utf8 = False 
self.message(200, "ok") 
else: 
self.message(500, "unrecognized option") 
elif cmd == "CDUP": 
finish = False 
arg = ".." 
else: 
finish = False 
if finish: return 
# Parse argument ( It's a path ) 
if arg == "": 
self.message(500, "where's my argument?") 
return 
remote, local, permission, vdir_list, limit_size, is_virtual =  
self.parse_path(arg) 
# can not do anything to virtual directory 
if is_virtual: permission = "none" 
can_read, can_write, can_modify = "read" in permission, "write" in permission, "modify" in permission 
newpath = local 
try: 
if cmd == "CWD": 
if(os.path.isdir(newpath)): 
self.curr_dir = remote 
self.full_path = newpath 
self.message(250, '"' + remote + '"') 
else: 
self.message(550, "failed") 
elif cmd == "MDTM": 
if os.path.exists(newpath): 
self.message(213, time.strftime("%Y%m%d%I%M%S", time.localtime( 
os.path.getmtime(newpath)))) 
else: 
self.message(550, "failed") 
elif cmd == "SIZE": 
self.message(231, os.path.getsize(newpath)) 
elif cmd == "XMKD" or cmd == "MKD": 
if not can_modify: 
self.message(550, "permission denied.") 
return 
os.mkdir(newpath) 
self.message(250, "ok") 
elif cmd == "RNFR": 
if not can_modify: 
self.message(550, "permission denied.") 
return 
self.temp_path = newpath 
self.message(350, "rename from " + remote) 
elif cmd == "RNTO": 
os.rename(self.temp_path, newpath) 
self.message(250, "RNTO to " + remote) 
elif cmd == "XRMD" or cmd == "RMD": 
if not can_modify: 
self.message(550, "permission denied.") 
return 
os.rmdir(newpath) 
self.message(250, "ok") 
elif cmd == "DELE": 
if not can_modify: 
self.message(550, "permission denied.") 
return 
os.remove(newpath) 
self.message(250, "ok") 
elif cmd == "RETR": 
if not os.path.isfile(newpath): 
self.message(550, "failed") 
return 
if not can_read: 
self.message(550, "permission denied.") 
return 
if not self.establish(): return 
self.message(150, "ok") 
f = open(newpath, "rb") 
while self.running: 
self.alive_time = time.time() 
data = f.read(8192) 
if len(data) == 0: break 
self.data_fd.send(data) 
f.close() 
self.data_fd.close() 
self.data_fd = 0 
self.message(226, "ok") 
elif cmd == "STOR" or cmd == "APPE": 
if not can_write: 
self.message(550, "permission denied.") 
return 
if os.path.exists(newpath) and not can_modify: 
self.message(550, "permission denied.") 
return 
# Check space size remained! 
used_size = 0 
if limit_size > 0: 
used_size = self.get_dir_size(os.path.dirname(newpath)) 
if not self.establish(): return 
self.message(150, "ok") 
f = open(newpath, ("ab" if cmd == "APPE" else "wb") ) 
while self.running: 
self.alive_time = time.time() 
data = self.data_fd.recv(8192) 
if len(data) == 0: break 
if limit_size > 0: 
used_size = used_size + len(data) 
if used_size > limit_size: break 
f.write(data) 
f.close() 
self.data_fd.close() 
self.data_fd = 0 
if limit_size > 0 and used_size > limit_size: 
self.message(550, "Exceeding user space limit: " + str(limit_size) + " bytes") 
else: 
self.message(226, "ok") 
else: 
self.message(500, cmd + " not implemented") 
except: 
self.message(550, "failed.") 

def establish(self): 
if self.data_fd == 0: 
self.message(500, "no data connection") 
return False 
if self.option_pasv: 
fd = self.data_fd.accept()[0] 
self.data_fd.close() 
self.data_fd = fd 
else: 
try: 
self.data_fd.connect((self.data_ip, self.data_port)) 
except: 
self.message(500, "failed to establish data connection") 
return False 
return True 

def read_virtual(self, path): 
vdir_list = [] 
path = path + "/.xxftp/virtual" 
if os.path.isfile(path): 
for v in open(path, "r").readlines(): 
items = v.split() 
items[1] = items[1].replace("$root", root_dir) 
vdir_list.append(items) 
return vdir_list 

def get_dir_size(self, folder): 
size = 0 
for path, dirs, files in os.walk(folder): 
for f in files: 
size += os.path.getsize(os.path.join(path, f)) 
return size 

def read_size(self, path): 
size = 0 
path = path + "/.xxftp/size" 
if os.path.isfile(path): 
size = int(open(path, "r").readline()) 
return size 

def read_permission(self, path): 
permission = "read,write,modify" 
path = path + "/.xxftp/permission" 
if os.path.isfile(path): 
permission = open(path, "r").readline() 
return permission 

def parse_path(self, path): 
if path == "": path = "." 
if path[0] != "/": 
path = self.curr_dir + "/" + path 
s = os.path.normpath(path).replace("\", "/").split("/") 
local = self.home_dir 
# reset directory permission 
vdir_list = self.read_virtual(local) 
limit_size = self.read_size(local) 
permission = self.read_permission(local) 
remote = "" 
is_virtual = False 
for name in s: 
name = name.lstrip(".") 
if name == "": continue 
remote = remote + "/" + name 
is_virtual = False 
for v in vdir_list: 
if v[0] == name: 
permission = v[2] 
local = v[1] 
limit_size = self.read_size(local) 
is_virtual = True 
if not is_virtual: local = local + "/" + name 
vdir_list = self.read_virtual(local) 
return (remote, local, permission, vdir_list, limit_size, is_virtual) 

def run(self): 
''' Connection Process ''' 
try: 
if len(conn_list) > max_connections: 
self.message(500, "too many connections!") 
self.fd.close() 
self.running = False 
return 
# Welcome Message 
if os.path.exists(root_dir + "/xxftp.welcome"): 
self.message(220, open(root_dir + "/xxftp.welcome").read()) 
else: 
self.message(220, "xxftp(Python) www.xiaoxia.org") 
# Command Loop 
line = "" 
while self.running: 
data = self.fd.recv(4096) 
if len(data) == 0: break 
line += data 
if line[-2:] != "rn": continue 
line = line[:-2] 
space = line.find(" ") 
if space == -1: 
self.process(line, "") 
else: 
self.process(line[:space], line[space+1:]) 
line = "" 
except: 
print "error", sys.exc_info() 
self.running = False 
self.fd.close() 
print "connection end", self.fd, "user", self.username 

def message(self, code, s): 
''' Send Ftp Message ''' 
s = str(s).replace("r", "") 
ss = s.split("n") 
if len(ss) > 1: 
r = (str(code) + "-") + ("rn" + str(code) + "-").join(ss[:-1]) 
r += "rn" + str(code) + " " + ss[-1] + "rn" 
else: 
r = str(code) + " " + ss[0] + "rn" 
if self.option_utf8: 
r = unicode(r, sys.getfilesystemencoding()).encode("utf8") 
self.fd.send(r) 

def server_listen(): 
global conn_list 
listen_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
listen_fd.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) 
listen_fd.bind((listen_ip, listen_port)) 
listen_fd.listen(1024) 
conn_lock = threading.Lock() 
print "ftpd is listening on ", listen_ip + ":" + str(listen_port) 

while True: 
conn_fd, remote_addr = listen_fd.accept() 
print "connection from ", remote_addr, "conn_list", len(conn_list) 
conn = FtpConnection(conn_fd) 
conn.start() 

conn_lock.acquire() 
conn_list.append(conn) 
# check timeout 
try: 
curr_time = time.time() 
for conn in conn_list: 
if int(curr_time - conn.alive_time) > conn_timeout: 
if conn.running == True: 
conn.fd.shutdown(socket.SHUT_RDWR) 
conn.running = False 
conn_list = [conn for conn in conn_list if conn.running] 
except: 
print sys.exc_info() 
conn_lock.release() 

def main(): 
server_listen() 

if __name__ == "__main__": 
main()