400多行Python代码实现了一个FTP服务器

Python版本
实现了比之前的xxftp更多更完善的功能
1、继续支持多用户
2、继续支持虚拟目录
3、增加支持用户根目录以及映射虚拟目录的权限设置
4、增加支持限制用户根目录或者虚拟目录的空间大小

xxftp的特点
1、开源、跨平台
2、简单、易用
3、不需要数据库
4、可扩展性超强
5、你可以免费使用xxftp假设自己的私人FTP服务器

测试地址
ftp://xiaoxia.org
匿名帐号可以使用！
匿名根目录只读，映射了一个虚拟目录，可以上传文件但不允许更改！

使用方法
跟之前用C语言写的xxftp使用方法一样：

1. Create a root directory to hold the user directories.
Configure it in config.xml.
2. 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
code of the password.
3. If you want to specify the welcome and goodbye message, write it in
xxftp.welcome and xxftp.goodbye under the root directory.
4. Configure config.xml.

The structure of your FTP server root may be like:

-/root
-xxftp.welcome
-xxftp.goodbye

-user1
-.xxftp
-password
-...
-user2
-.xxftp
-password
-...
-anonymous源代码

代码如下:

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 + "\r\n"
else:
info = "d%s%s------- %04u %8s %8s %8lu %s %s\r\n" % (
"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 + "\r\n"
else:
st = os.stat(path)
info = "%s%s%s------- %04u %8s %8s %8lu %s %s\r\n" % (
"-" 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:\r\nSITES\r\nEPRT\r\nEPSV\r\nMDTM\r\nPASV\r\n"\
"REST STREAM\r\nSIZE\r\nUTF8\r\n211 End\r\n"
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:] != "\r\n": 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) + "-") + ("\r\n" + str(code) + "-").join(ss[:-1])
r += "\r\n" + str(code) + " " + ss[-1] + "\r\n"
else:
r = str(code) + " " + ss[0] + "\r\n"
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()