Socket函数编程
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粘包问题
1.修改数据长度：
client端
1 import socket 2 3 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) 4 #拨通电话 5 ip_port = (\'127.0.0.1\',8081) 6 phone.connect(ip_port) 7 8 while True: 9 #发消息 10 cmd = input(\'>>: \').strip() 11 if not cmd:continue 12 phone.send(bytes(cmd,encoding=\'utf-8\')) 13 #收消息 14 data = phone.recv(1024) #8192 15 print(data.decode(\'gbk\')) 16 phone.close()
#输出 长于1024字节的不行
server端
import socket import subprocess phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) #SOCK_STREAM tcp # ip_port=(\'127.0.0.1\',808) phone.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1) ip_port=(\'127.0.0.1\',8081) phone.bind(ip_port) phone.listen(5) #开机 while True: conn,client_addr=phone.accept() while True: try: cmd = conn.recv(1024) if not cmd:break res = subprocess.Popen(cmd.decode(\'utf-8\'), shell=True, stderr=subprocess.PIPE, stdout=subprocess.PIPE ) # err=res.stderr.read() # if err: # cmd_res=err # else: # cmd_res=res.stdout.read() conn.send(res.stdout.read()) conn.send(res.stderr.read()) except Exception: break conn.close() phone.close()
client端
1 import socket 2 import subprocess 3 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) 4 #拨通电话 5 ip_port = (\'127.0.0.1\',8080) 6 phone.connect(ip_port) 7 8 phone.send(\'helloworld\'.encode(\'utf-8\')) 9 phone.send(\'SB\'.encode(\'utf-8\'))
#输出
第一个包 b\'helloworldSB\'
第二个包 b\'\'
服务器端
1 import socket 2 import subprocess 3 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) #SOCK_STREAM tcp 4 ip_port=(\'127.0.0.1\',8080) 5 phone.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1) 6 7 phone.bind(ip_port) 8 phone.listen(5) #开机 9 conn,client_addr=phone.accept() 10 11 data1=conn.recv(1024) 12 data2=conn.recv(1024) 13 14 print(\'第一个包\',data1) 15 print(\'第二个包\',data2)
改进
2.修改时间长度
client端
1 import socket,time 2 import subprocess 3 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) 4 #拨通电话 5 ip_port = (\'127.0.0.1\',8080) 6 phone.connect(ip_port) 7 8 phone.send(\'helloworld\'.encode(\'utf-8\')) #客户端都是发到自己的缓存里了 9 time.sleep(3) #网络延迟没有三秒长 10 phone.send(\'SB\'.encode(\'utf-8\'))
server端
1 import socket 2 import subprocess,time 3 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) #SOCK_STREAM tcp 4 ip_port=(\'127.0.0.1\',8080) 5 phone.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1) 6 7 phone.bind(ip_port) 8 phone.listen(5) #开机 9 conn,client_addr=phone.accept() 10 11 data1=conn.recv(1) #conn.recv(1024) 12 time.sleep(5) 13 data2=conn.recv(1024) 14 15 print(\'第一个包\',data1) 16 print(\'第二个包\',data2)
TCP流式协议，
所谓粘包问题主要还是因为接收方不知道消息之间的界限，不知道一次性提取多少字节的数据所造成的。（TCP是流式协议）
此外，发送方引起的粘包是由TCP协议本身造成的，TCP为提高传输效率，发送方往往要收集到足够多的数据后才发送一个TCP段。若连续几次需要send的数据都很少，通常TCP会根据优化算法把这些数据合成一个TCP段后一次发送出去，这样接收方就收到了粘包数据。
- TCP（transport control protocol，传输控制协议）是面向连接的，面向流的，提供高可靠性服务。收发两端（客户端和服务器端）都要有一一成对的socket，因此，发送端为了将多个发往接收端的包，更有效的发到对方，使用了优化方法（Nagle算法），将多次间隔较小且数据量小的数据，合并成一个大的数据块，然后进行封包。这样，接收端，就难于分辨出来了，必须提供科学的拆包机制。 即面向流的通信是无消息保护边界的。
- UDP（user datagram protocol，用户数据报协议）是无连接的，面向消息的，提供高效率服务。不会使用块的合并优化算法，, 由于UDP支持的是一对多的模式，所以接收端的skbuff(套接字缓冲区）采用了链式结构来记录每一个到达的UDP包，在每个UDP包中就有了消息头（消息来源地址，端口等信息），这样，对于接收端来说，就容易进行区分处理了。 即面向消息的通信是有消息保护边界的。
- tcp是基于数据流的，于是收发的消息不能为空，这就需要在客户端和服务端都添加空消息的处理机制，防止程序卡住，而udp是基于数据报的，即便是你输入的是空内容（直接回车），那也不是空消息，udp协议会帮你封装上消息头，实验略
tcp的协议数据不会丢，没有收完包，下次接收，会继续上次继续接收，己端总是在收到ack时才会清除缓冲区内容。数据是可靠的，但是会粘包。
所以，发包时一定要给包定义一个头部。
3.stuct模块解决粘包
为字节流加上自定义固定长度报头，报头中包含字节流长度，然后一次send到对端，对端在接收时，先从缓存中取出定长的报头，然后再取真实数据
报头： 1.固定长度 2.包含对发送数据的描述信息
自定义报头（普通）
client端
1 import socket 2 import struct 3 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) 4 #拨通电话 5 ip_port = (\'192.168.16.134\',8080) 6 phone.connect(ip_port) 7 #通信循环 8 while True: 9 #发消息 10 cmd = input(\'>>: \').strip() 11 if not cmd:continue 12 phone.send(bytes(cmd,encoding=\'utf-8\')) 13 #收报头 14 baotou = phone.recv(4) #8192 15 data_size=struct.unpack(\'i\',baotou)[0] 16 17 #收数据 18 recv_size=0 19 recv_data=b\'\' 20 while recv_size < data_size: 21 data=phone.recv(1024) 22 recv_size+=len(data) 23 recv_data+=data 24 print(recv_data.decode(\'utf-8\')) 25 phone.close()
server端
1 #/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 import socket 4 import struct 5 import subprocess 6 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) 7 ip_port=(\'192.168.16.134\',8080) 8 9 phone.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1) 10 phone.bind(ip_port) 11 12 phone.listen(5) 13 while True: 14 conn,client_addr=phone.accept() 15 16 while True: 17 try: 18 cmd = conn.recv(1024) 19 if not cmd:break 20 res = subprocess.Popen(cmd.decode(\'utf-8\'), 21 shell=True, 22 stderr=subprocess.PIPE, 23 stdout=subprocess.PIPE 24 ) 25 out_res=res.stdout.read() 26 err_res=res.stderr.read() 27 data_size=str(len(out_res)+len(err_res)).encode(\'utf-8\') 28 #发送报头 29 conn.send(struct.pack(\'i\',data_size)) 30 #发送数据部分 31 conn.send(out_res) 32 conn.send(err_res) 33 except Exception: 34 break 35 36 conn.close() 37 phone.close()
struct.error: \'i\' format requires -2147483648 <= number <= 2147483647 #这个是范围
自定义报头(jason)
server端
1 #/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 import socket 4 import struct 5 import subprocess 6 import json 7 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) 8 ip_port=(\'192.168.16.134\',8080) 9 10 phone.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1) 11 phone.bind(ip_port) 12 13 phone.listen(5) 14 while True: 15 conn,client_addr=phone.accept() 16 17 while True: 18 try: 19 cmd = conn.recv(1024) 20 if not cmd:break 21 res = subprocess.Popen(cmd.decode(\'utf-8\'), 22 shell=True, 23 stderr=subprocess.PIPE, 24 stdout=subprocess.PIPE 25 ) 26 out_res=res.stdout.read() 27 err_res=res.stderr.read() 28 data_size=len(out_res)+len(err_res) 29 head_dic={\'data_size\':data_size} 30 head_json=json.dumps(head_dic) 31 head_bytes=head_json.encode(\'utf-8\') 32 #part1:先发报头的长度 33 head_len=len(head_bytes) 34 conn.send(struct.pack(\'i\',head_len)) 35 #part2:再发送报头 36 conn.send(head_bytes) 37 #part3:最后发送数据部分 38 conn.send(out_res) 39 conn.send(err_res) 40 except Exception: 41 break 42 43 conn.close() 44 phone.close()
client端
1 import socket 2 import struct 3 import json 4 phone=socket.socket(socket.AF_INET,socket.SOCK_STREAM) 5 #拨通电话 6 ip_port = (\'192.168.16.134\',8080) 7 phone.connect(ip_port) 8 #通信循环 9 while True: 10 #发消息 11 cmd = input(\'>>: \').strip() 12 if not cmd:continue 13 phone.send(bytes(cmd,encoding=\'utf-8\')) 14 15 #part1:先收报头的长度 16 head_struct=phone.recv(4) 17 print(struct.unpack(\'i\',head_struct)) 18 head_len=struct.unpack(\'i\',head_struct)[0] 19 20 #part2:再收报头 21 head_bytes=phone.recv(head_len) 22 head_json=head_bytes.decode(\'utf-8\') 23 24 head_dic=json.loads(head_json) 25 print(head_dic) 26 data_size=head_dic[\'data_size\'] 27 28 #part3收数据 29 recv_size=0 30 recv_data=b\'\' 31 while recv_size < data_size: 32 data=phone.recv(1024) 33 recv_size+=len(data) 34 recv_data+=data 35 print(recv_data.decode(\'utf-8\')) 36 phone.close()
报头类似于字典，先做字典，字典转成json格式，保证发过去还有结构的。把json字符串转成bytes格式，有了它可以发送报头的。
发送时：服务器端struct模块把报头长度打成bytes,先发报头长度，在发报头，再发真实数据。
接收时：客户端通过struct模块拿到报头长度，再recv收到报头长度，解码，反序列化得到字典，再从字典里拿到真实数据
FTP上传下载
服务端
import socket import struct import json import subprocess import os class MYTCPServer: address_family = socket.AF_INET socket_type = socket.SOCK_STREAM allow_reuse_address = False max_packet_size = 8192 coding=\'utf-8\' request_queue_size = 5 server_dir=\'file_upload\' def __init__(self, server_address, bind_and_activate=True): """Constructor. May be extended, do not override.""" self.server_address=server_address self.socket = socket.socket(self.address_family, self.socket_type) if bind_and_activate: try: self.server_bind() self.server_activate() except: self.server_close() raise def server_bind(self): """Called by constructor to bind the socket. """ if self.allow_reuse_address: self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self.socket.bind(self.server_address) self.server_address = self.socket.getsockname() def server_activate(self): """Called by constructor to activate the server. """ self.socket.listen(self.request_queue_size) def server_close(self): """Called to clean-up the server. """ self.socket.close() def get_request(self): """Get the request and client address from the socket. """ return self.socket.accept() def close_request(self, request): """Called to clean up an individual request.""" request.close() def run(self): while True: self.conn,self.client_addr=self.get_request() print(\'from client \',self.client_addr) while True: try: head_struct = self.conn.recv(4) if not head_struct:break head_len = struct.unpack(\'i\', head_struct)[0] head_json = self.conn.recv(head_len).decode(self.coding) head_dic = json.loads(head_json) print(head_dic) #head_dic={\'cmd\':\'put\',\'filename\':\'a.txt\',\'filesize\':123123} cmd=head_dic[\'cmd\'] if hasattr(self,cmd): func=getattr(self,cmd) func(head_dic) except Exception: break def put(self,args): file_path=os.path.normpath(os.path.join( self.server_dir, args[\'filename\'] )) filesize=args[\'filesize\'] recv_size=0 print(\'----->\',file_path) with open(file_path,\'wb\') as f: while recv_size < filesize: recv_data=self.conn.recv(self.max_packet_size) f.write(recv_data) recv_size+=len(recv_data) print(\'recvsize:%s filesize:%s\' %(recv_size,filesize)) tcpserver1=MYTCPServer((\'127.0.0.1\',8080)) tcpserver1.run() #下列代码与本题无关 class MYUDPServer: """UDP server class.""" address_family = socket.AF_INET socket_type = socket.SOCK_DGRAM allow_reuse_address = False max_packet_size = 8192 coding=\'utf-8\' def get_request(self): data, client_addr = self.socket.recvfrom(self.max_packet_size) return (data, self.socket), client_addr def server_activate(self): # No need to call listen() for UDP. pass def shutdown_request(self, request): # No need to shutdown anything. self.close_request(request) def close_request(self, request): # No need to close anything. pass 服务端
import socket import struct import json import os class MYTCPClient: address_family = socket.AF_INET socket_type = socket.SOCK_STREAM allow_reuse_address = False max_packet_size = 8192 coding=\'utf-8\' request_queue_size = 5 def __init__(self, server_address, connect=True): self.server_address=server_address self.socket = socket.socket(self.address_family, self.socket_type) if connect: try: self.client_connect() except: self.client_close() raise def client_connect(self): self.socket.connect(self.server_address) def client_close(self): self.socket.close() def run(self): while True: inp=input(">>: ").strip() if not inp:continue l=inp.split() cmd=l[0] if hasattr(self,cmd): func=getattr(self,cmd) func(l) def put(self,args): cmd=args[0] filename=args[1] if not os.path.isfile(filename): print(\'file:%s is not exists\' %filename) return else: filesize=os.path.getsize(filename) head_dic={\'cmd\':cmd,\'filename\':os.path.basename(filename),\'filesize\':filesize} print(head_dic) head_json=json.dumps(head_dic) head_json_bytes=bytes(head_json,encoding=self.coding) head_struct=struct.pack(\'i\',len(head_json_bytes)) self.socket.send(head_struct) self.socket.send(head_json_bytes) send_size=0 with open(filename,\'rb\') as f: for line in f: self.socket.send(line) send_size+=len(line) print(send_size) else: print(\'upload successful\') client=MYTCPClient((\'192.168.16.134\',8080)) client.run()
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