我的FTP Server——ftp.py
在上文中，我们简要地学习了下FTP协议，链接 /ftp-protocol.html。
有兴趣的同学们可以去围观下。
因为最近偶看了下FTP协议，所以决定写个FTP Server玩玩。毕竟一直写的都是应用程序，于是乎想写下服务器端的程序。
结果就有了ftp.py，名字灵感来源于web.py。
ftp.py
ftp.py由Python 2.x实现。目前有部署到我的服务器上。支持Windows、Unix和类Unix系统。支持多线程模式和多进程模式，不过在Windows上仅支持多线程模式。支持虚拟用户。
其中多进程模式支持以其他用户身份运行，加强了安全性。
usage: ftp.py [-d] [-h] [-p port] [-o] [-t]
-d become a daemon
-h help
-p listen port
-o output log to stdout, by default, it outputs to a log file.
-t thread mode, fork model by default其中用户设置写在ftp.py.config中，如果文件不存在则默认使用anonymous账户。
用户设置文件ftp.py.config格式如下：
account_info = { ‘et’:{‘pass’:‘123456789’, ‘home_dir’:‘/root/’}, ‘lst’:{‘pass’:‘987654321’, ‘home_dir’:‘/tmp/’} }
也就是账户名+密码+家目录路径。
ftp.py.config
我们还可以在ftp.py的同级目录中通过ftp.py.config设置我们的FTP Server。
最大用户连接数 limit_connection_number
“超时时间（单位：秒）timeout
“默认家目录：default_home_dir
日志文件：logfile
运行的用户身份：runas_user
默认值为：
limit_connection_number = 5 # max client number
timeout = 60 * 3 # timeout in second
default_home_dir = os.path.normpath(os.path.abspath(os.curdir)).replace('\\', '/')
logfile = '/var/log/ftp.py.log' if os.name == 'posix' else default_home_dir + 'ftp.py.log'
runas_user = 'www-data'源码如下：
最新的源码请见Git: https://github.com/cedricporter/ftp.py
#!/usr/bin/env python
# author: Hua Liang [ Stupid ET ]
# email: et@everet.org
# website:
#
import socket, os, stat, threading, time, struct, getopt
import sys, re, signal, select, logging, logging.handlers
host = '0.0.0.0'
port = 21
limit_connection_number = 5 # max client number
timeout = 60 * 3 # timeout in second
default_home_dir = os.path.normpath(os.path.abspath(os.curdir)).replace('\\', '/')
logfile = '/var/log/ftp.py.log' if os.name == 'posix' else default_home_dir + 'ftp.py.log'
runas_user = 'www-data'
global_options = {'run_mode':'fork'}
# current working directory
account_info = {
'anonymous':{'pass':'', 'home_dir':default_home_dir, 'runas_user':runas_user},
}
def runas(username):
if os.name != 'posix': return
uid = get_uid(username)
os.setgid(uid)
os.setuid(uid)
class FTPConnection:
'''You can add handle func by startswith handle_ prefix.
When the connection receives CWD command, it'll use handle_CWD to handle it.
'''
def __init__(self, fd, remote_ip):
self.fd = fd
self.data_fd = 0
self.options = {'pasv': False, 'utf8': False}
self.data_host = ''
self.data_port = 0
self.localhost = fd.getsockname()[0]
self.home_dir = default_home_dir
self.curr_dir = '/'
self.running = True
self.handler = dict(
[(method[7:], getattr(self, method)) \
for method in dir(self) \
if method.startswith("handle_") and callable(getattr(self, method))])
def start(self):
try:
self.say_welcome()
while self.running:
success, command, arg = self.recv()
command = command.upper()
if self.options['utf8']:
arg = unicode(arg, 'utf8').encode(sys.getfilesystemencoding())
logger.info('[ ' + command + ' ] ' + arg)
if not success:
self.send_msg(500, "Failed")
continue
if not self.handler.has_key(command):
self.send_msg(500, "Command Not Found")
continue
try:
self.handler[command](arg)
except OSError, e:
logger.error(e)
logger.error("in start")
self.send_msg(500, 'Permission denied')
self.say_bye()
except Exception, e:
self.running = False
logger.error(e)
logger.error("in start")
finally:
self.fd.close()
logger.info("FTP connnection done.")
return True
def send_msg(self, code, msg):
if self.options['utf8']:
msg = unicode(msg, sys.getfilesystemencoding()).encode('utf8')
message = str(code) + ' ' + msg + '\r\n'
self.fd.send(message)
def recv(self):
'''returns 3 tuples, success, command, arg'''
try:
success, buf, command, arg = True, '', '', ''
while True:
data = self.fd.recv(4096)
if not data or data <= 0:
self.running = False
success = False
break
buf += data
if buf[-2:] == '\r\n': break
split = buf.find(' ')
command, arg = (buf[:split], buf[split + 1:].strip()) if split != -1 else (buf.strip(), '')
except Exception, e:
logger.error(e)
logger.error("in recv")
self.running = False
success = False
return success, command, arg
def say_welcome(self):
self.send_msg(220, "Welcome to EverET.org FTP")
def say_bye(self):
self.handle_BYE('')
def data_connect(self):
'''establish data connection'''
if self.data_fd == 0:
self.send_msg(500, "no data connection")
return False
elif self.options['pasv']:
fd, addr = self.data_fd.accept()
self.data_fd.close()
self.data_fd = fd
else:
try:
self.data_fd.connect((self.data_host, self.data_port))
except:
self.send_msg(500, "failed to connect")
return False
return True
def close_data_fd(self):
self.data_fd.close()
self.data_fd = 0
def parse_path(self, path):
if path == '': path = '.'
if path[0] != '/': path = self.curr_dir + '/' + path
logger.info('parse_path ' + path)
split_path = os.path.normpath(path).replace('\\', '/').split('/')
remote = ''
local = self.home_dir
for item in split_path:
if item.startswith('..') or item == '': continue # ignore parent directory
remote += '/' + item
local += '/' + item
if remote == '': remote = '/'
logger.info(split_path)
logger.info('remote: %s local: %s' % (remote, local))
return remote, local
# Command Handlers
def handle_USER(self, arg):
if arg in account_info:
self.username = arg
if self.username == 'anonymous':
self.send_msg(230, 'OK')
else:
self.send_msg(331, "Need password")
else:
self.send_msg(500, "Invalid User")
self.running = False
def handle_PASS(self, arg):
if arg == account_info[self.username]['pass']:
self.home_dir = account_info[self.username]['home_dir']
if account_info[self.username].has_key('runas_user'):
user = account_info[self.username]['runas_user']
else:
user = 'www-data'
runas(user)
if os.path.isdir(self.home_dir):
self.send_msg(230, "OK")
return
self.send_msg(530, "Password is not corrected")
self.running = False
def handle_QUIT(self, arg):
self.handle_BYE(arg)
def handle_BYE(self, arg):
self.running = False
self.send_msg(200, "OK")
def handle_CDUP(self, arg):
self.handle_CWD('..')
def handle_XPWD(self, arg):
self.handle_PWD(arg)
def handle_PWD(self, arg):
remote, local = self.parse_path(self.curr_dir)
self.send_msg(257, '"' + remote + '"')
def handle_CWD(self, arg):
remote, local = self.parse_path(arg)
try:
os.listdir(local)
self.curr_dir = remote
self.send_msg(250, "OK")
except Exception, e:
logger.error(e)
logger.error("in cwd")
self.send_msg(500, "Change directory failed!")
def handle_SIZE(self, arg):
remote, local = self.parse_path(self.curr_dir)
self.send_msg(231, str(os.path.getsize(local)))
def handle_SYST(self, arg):
self.send_msg(215, "UNIX")
def handle_STOR(self, arg):
remote, local = self.parse_path(arg)
if not self.data_connect(): return
self.send_msg(125, "OK")
f = open(local, 'wb')
while True:
data = self.data_fd.recv(8192)
if len(data) == 0: break
f.write(data)
f.close()
self.close_data_fd()
self.send_msg(226, "OK")
def handle_RETR(self, arg):
remote, local = self.parse_path(arg)
if not self.data_connect(): return
self.send_msg(125, "OK")
f = open(local, 'rb')
while True:
data = f.read(8192)
if len(data) == 0: break
self.data_fd.send(data)
f.close()
self.close_data_fd()
self.send_msg(226, "OK")
def handle_TYPE(self, arg):
self.send_msg(220, "OK")
def handle_RNFR(self, arg):
remote, local = self.parse_path(arg)
self.rename_tmp_path = local
self.send_msg(350, 'rename from ' + remote)
def handle_RNTO(self, arg):
remote, local = self.parse_path(arg)
os.rename(self.rename_tmp_path, local)
self.send_msg(250, 'rename to ' + remote)
def handle_NLST(self, arg):
if not self.data_connect(): return
self.send_msg(125, "OK")
remote, local = self.parse_path(self.curr_dir)
for filename in os.listdir(local):
self.data_fd.send(filename + '\r\n')
self.send_msg(226, "Limit")
self.close_data_fd()
def handle_XMKD(self, arg):
self.handle_MKD(arg)
def handle_MKD(self, arg):
remote, local = self.parse_path(arg)
if os.path.exists(local):
self.send_msg(500, "Folder is already existed")
return
os.mkdir(local)
self.send_msg(257, "OK")
def handle_XRMD(self, arg):
self.handle_RMD(arg)
def handle_RMD(self, arg):
remote, local = self.parse_path(arg)
if not os.path.exists(local):
self.send_msg(500, "Folder is not existed")
return
os.rmdir(local)
self.send_msg(250, "OK")
def handle_LIST(self, arg):
if not self.data_connect(): return
self.send_msg(125, "OK")
template = "%s%s%s------- %04u %8s %8s %8lu %s %s\r\n"
remote, local = self.parse_path(self.curr_dir)
for filename in os.listdir(local):
path = local + '/' + filename
if os.path.isfile(path) or os.path.isdir(path): # ignores link or block file
status = os.stat(path)
msg = template % (
'd' if os.path.isdir(path) else '-',
'r', 'w', 1, '0', '0',
status[stat.ST_SIZE],
time.strftime("%b %d %Y", time.localtime(status[stat.ST_MTIME])),
filename)
if self.options['utf8']: msg = unicode(msg, sys.getfilesystemencoding()).encode('utf8')
self.data_fd.send(msg)
self.send_msg(226, "Limit")
self.close_data_fd()
def handle_PASV(self, arg):
self.options['pasv'] = True
try:
self.data_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.data_fd.bind((self.localhost, 0))
self.data_fd.listen(1)
ip, port = self.data_fd.getsockname()
self.send_msg(227, 'Enter Passive Mode (%s,%u,%u).' %
(','.join(ip.split('.')), (port >> 8 & 0xff), (port & 0xff)))
except Exception, e:
logger.error(e)
logger.error("in pasv")
self.send_msg(500, 'passive mode failed')
def handle_PORT(self, arg):
try:
if self.data_fd:
self.data_fd.close()
t = arg.split(',')
self.data_host = '.'.join(t[:4])
self.data_port = int(t[4]) * 256 + int(t[5])
self.data_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except:
self.send_msg(500, "PORT failed")
self.send_msg(200, "OK")
def handle_DELE(self, arg):
remote, local = self.parse_path(arg)
if not os.path.exists(local):
self.send_msg(450, "File not exist")
return
os.remove(local)
self.send_msg(250, 'File deleted')
def handle_OPTS(self, arg):
if arg.upper() == "UTF8 ON":
self.options['utf8'] = True
self.send_msg(200, "OK")
elif arg.upper() == "UTF8 OFF":
self.options['utf8'] = False
self.send_msg(200, "OK")
else:
self.send_msg(500, "Invalid argument")
class FTPThread(threading.Thread):
'''FTPConnection Thread Wrapper'''
def __init__(self, fd, remote_ip):
threading.Thread.__init__(self)
self.ftp = FTPConnection(fd, remote_ip)
def run(self):
self.ftp.start()
logger.info("Thread done")
class FTPThreadServer:
'''FTP Server which is using thread'''
def serve_forever(self):
listen_fd = socket.socket()
listen_fd.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
listen_fd.bind((host, port))
listen_fd.listen(512)
while True:
logger.info('new server')
client_fd, client_addr = listen_fd.accept()
handler = FTPThread(client_fd, client_addr)
handler.start()
class FTPForkServer:
'''FTP Fork Server, use process per user'''
def child_main(self, client_fd, client_addr, write_end):
'''never return'''
for fd in self.read_fds:
os.close(fd)
self.read_fds = []
try:
handler = FTPConnection(client_fd, client_addr)
handler.start()
except Exception, e:
logger.error(e)
logger.error("in child_main")
os.write(write_end, str(write_end))
sys.exit()
def serve_forever(self):
listen_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
listen_fd.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
listen_fd.bind((host, port))
listen_fd.listen(512)
self.read_fds = [listen_fd]
while True:
rlist, wlist, xlist = select.select(self.read_fds, [], [])
if listen_fd in rlist:
client_fd, client_addr = listen_fd.accept()
if len(self.read_fds) > limit_connection_number:
logger.error('reject client: ' + str(client_addr))
client_fd.close()
continue
try:
logger.info('new client: ' + str(client_addr))
read_end, write_end = os.pipe()
self.read_fds.append(read_end)
fork_result = os.fork()
if fork_result == 0: # child process
listen_fd.close()
self.read_fds.remove(listen_fd)
self.child_main(client_fd, client_addr, write_end) # never return
else:
os.close(write_end)
except Exception, e:
logger.error(e)
logger.error('Fork failed')
for read_fd in rlist:
if read_fd == listen_fd: continue
data = os.read(read_fd, 32)
self.read_fds.remove(read_fd)
os.close(read_fd)
def get_uid(username = 'www-data'):
'''get uid by username, I don't know whether there's a
function can get it, so I wrote this function.'''
pwd = open('/etc/passwd', 'r')
pat = re.compile(username + ':.*?:(.*?):.*?')
for line in pwd.readlines():
try:
uid = pat.search(line).group(1)
except: continue
return int(uid)
def get_logger(handler = logging.StreamHandler()):
logger = logging.getLogger()
formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
handler.setFormatter(formatter)
logger.addHandler(handler)
logger.setLevel(logging.NOTSET)
return logger
def daemonize(stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
'''becomes a daemon'''
try:
pid = os.fork()
if pid > 0: sys.exit(0)
except OSError, e:
sys.stderr.write("fork #1 failed\n")
sys.exit(1)
os.umask(0)
os.setsid()
try:
pid = os.fork()
if pid > 0: sys.exit(0)
except OSError, e:
sys.stderr.write("fork #2 failed\n")
sys.exit(1)
for f in sys.stdout, sys.stderr: f.flush()
si = file(stdin, 'r')
so = file(stdout, 'a+')
se = file(stderr, 'a+', 0)
os.dup2(si.fileno(), sys.stdin.fileno()) # 0
os.dup2(so.fileno(), sys.stdout.fileno()) # 1
os.dup2(se.fileno(), sys.stderr.fileno()) # 2
def serve_forever():
global global_options
print global_options
if global_options['run_mode'] == 'fork':
signal.signal(signal.SIGCHLD, signal.SIG_IGN)
server = FTPForkServer()
else:
server = FTPThreadServer()
server.serve_forever()
def usage():
print '''usage: %s [-d] [-h] [-p port] [-o] [-t]
-d become a daemon
-h help
-p listen port
-o output log to stdout, by default, it outputs to a log file.
-t thread mode, fork model by default
Waring:
The Thread Mode is not complete.
Author:
Hua Liang [ Stupid ET ] <et@everet.org>
''' % os.path.basename(sys.argv[0])
def param_handler(opts):
global port, logger, global_options
be_daemon = False
logger = get_logger(logging.FileHandler(logfile))
for o, a in opts:
if o == '-h':
usage()
sys.exit(0)
elif o == '-d':
if not os.name == 'posix':
print 'Only support the os with posix specifications.'
sys.exit(-1)
be_daemon = True
elif o == '-o':
logger = get_logger()
elif o == '-p':
try: port = int(a)
except Exception, e:
usage()
sys.exit(0)
elif o == '-t':
global_options['run_mode'] = 'thread'
if os.name != 'posix' and global_options['run_mode'] == 'fork':
print "You can NOT run fork mode in a non posix os,\
please use -t options to run in thread mode"
sys.exit(-1)
if be_daemon: daemonize()
if __name__ == '__main__':
try:
opts, args = getopt.getopt(sys.argv[1:], 'hdp:ot')
except getopt.GetoptError:
usage()
sys.exit(2)
param_handler(opts)
socket.setdefaulttimeout(timeout)
'''You can write your account_info in ftp.py.config'''
try: execfile('ftp.py.config')
except Exception, e: logger.error(e)
serve_forever()