tftp在遠程登錄中有什么用，python實現簡單tftp(基于udp)

• tftp是基于udp的協議
• 實現簡單的tftp，首先要有tftp的協議圖。
• tftp默認接收端口為69，但每次有連接過來后，tftp會隨機分配一個端口來專門為這個連接來服務。
• 操作碼：1.上傳 2.下載 3.傳數據 4.接收確認 5.錯誤碼?

tftp服務器簡單實現：

from threading import Thread
from socket import *
import structdef upload(filename,user_ip,user_port):num = 0f = open(filename,'ab') s_up = socket(AF_INET,SOCK_DGRAM)send_data_1 = struct.pack("!HH",4,num)s_up.sendto(send_data_1,(user_ip,user_port))  #第一次用隨機端口發送while True:recv_data,user_info = s_up.recvfrom(1024)  #第二次客戶連接我隨機端口caozuohao_up,ack_num = struct.unpack('!HH',recv_data[:4])print(caozuohao_up,ack_num,num)if int(caozuohao_up) == 3 and ack_num == num :f.write(recv_data[4:])send_data = struct.pack("!HH",4,num)s_up.sendto(send_data,(user_ip,user_port)) #第二次我用隨機端口發num = num + 1if len(recv_data) < 516:print(user_ip+'上傳文件'+filename+':完成')f.close()exit()def download(filename,user_ip,user_port):s_down = socket(AF_INET, SOCK_DGRAM)num = 0try:f = open(filename,'rb')except:error_data = struct.pack('!HHHb',5,5,5,num)s_down.sendto(error_data, (user_ip,user_port))  #文件不存在時發送exit()  #只會退出此線程while True:read_data = f.read(512)send_data = struct.pack('!HH',3,num) + read_datas_down.sendto(send_data, (user_ip,user_port))  #數據第一次發送if len(read_data) < 512:print('傳輸完成, 對方下載成功')exit()        recv_ack =  s_down.recv(1024)  #第二次接收caozuoma,ack_num = struct.unpack("!HH", recv_ack)
#        print(caozuoma,ack_num,len(read_data))num += 1if int(caozuoma) != 4 or int(ack_num) != num-1 :exit()f.close()s = socket(AF_INET,SOCK_DGRAM)
s.bind(('',69))def main():while 1:recv_data,(user_ip,user_port) = s.recvfrom(1024)  #第一次客戶連接69端口print(recv_data, user_ip, user_port)if struct.unpack('!b5sb',recv_data[-7:]) == (0, b'octet', 0):caozuoma = struct.unpack('!H',recv_data[:2])filename = recv_data[2:-7].decode('gb2312')if caozuoma[0] == 1:print('對方想下載數據',filename)t = Thread(target = download, args = (filename,user_ip,user_port)) t.start()           elif caozuoma[0] == 2:print('對方想上傳數據',filename)t = Thread(target = upload, args = (filename,user_ip,user_port)) t.start()           if __name__ == '__main__':main()

上傳數據簡單實現：

#!/usr/bin/env python3
#coding=utf-8import struct
from socket import *server_ip = '192.168.119.157'
send_data_1 = struct.pack('!H8sb5sb',2,'王輝.jpg'.encode('gb2312'),0,b'octet',0)
s = socket(AF_INET,SOCK_DGRAM)
s.sendto(send_data_1,(server_ip,69)) #第一次發給服務器69端口

f = open('王輝.jpg','rb')recv_data = s.recvfrom(1024) #第一次接收數據
rand_port = recv_data[1][1]
print()
ack_num = struct.unpack("!HH",recv_data[0][:4])
num = 0
while True:read_data = f.read(512)send_data = struct.pack('!HH',3,num) + read_datas.sendto(send_data,(server_ip,rand_port)) #第二次發給服務器的隨機端口recv_data_2,userinfo = s.recvfrom(1024)print(recv_data_2)ack_num = struct.unpack('!H',recv_data_2[2:4])print(len(read_data),num,ack_num[0],rand_port)if len(read_data) < 512 or ack_num[0] != num :breaknum = num + 1

下載數據簡單實現：

#!/usr/bin/env python3
#coding=utf-8import struct
from socket import *filename = 'test.jpg'
server_ip = '192.168.1.113'send_data = struct.pack('!H%dsb5sb'%len(filename),1,filename.encode('gb2312'),0,'octet'.encode('gb2312'),0)
s = socket(AF_INET,SOCK_DGRAM)
s.sendto(send_data,(server_ip,69)) #第一次發送, 連接服務器69端口

f = open(filename,'ab')while 1:recv_data = s.recvfrom(1024) #接收數據caozuoma,ack_num = struct.unpack('!HH',recv_data[0][:4]) #獲取數據塊編號rand_port = recv_data[1][1]  #獲取服務器的隨機端口if int(caozuoma) == 5:print('服務器返回: 文件不存在...')breakprint(caozuoma,ack_num,rand_port,len(recv_data[0]))f.write(recv_data[0][4:])if len(recv_data[0]) < 516:breakack_data = struct.pack("!HH",4,ack_num)s.sendto(ack_data,(server_ip,rand_port))  #回復ACK確認包

?