400多行Python代码实现了一个FTP服务器

 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() 

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