day30——socket套接字（完全版）

day30

基于TCP协议的socket循环通信

server

import socket
phone = socket.socket()
phone.bind(("127.0.0.1", 8080))
phone.listen()
conn, addr = phone.accept()

from_client_data = conn.recv(1024)
print(f"来自客户端的消息：{from_client_data.decode('utf-8')}")

conn.close()
phone.close()

client

import socket
phone = socket.socket()
phone.connect(("127.0.0.1", 8080))
data = input("请输入>>>")
phone.send(data.encode("utf-8"))
phone.close()

基于TCP协议的socket 链接+循环 通信

代码功能：服务器不会断开，客户端可以断开（且不能输入空字符串）

server

import socket
phone = socket.socket()
phone.bind(("127.0.0.1", 8080))
phone.listen(3)
while 1:
    conn, addr = phone.accept()
    print(f"{addr}客户端连接了")
    while 1:
        try:
            from_client_data = conn.recv(1024)
            if from_client_data.decode("utf-8").upper() == "Q":
                print(f"{addr}客户端通信关闭！")
                break
            else:
                print(f"来自客户端的消息：{from_client_data.decode('utf-8')}")
            while True:
                data = input("请输入>>>")
                if not data:
                    print("输入内容不为空！")
                    continue
                else:
                    break
            conn.send(data.encode("utf-8").upper())
        except Exception:
            print(f"{addr}客户端通信关闭！")
            break
    conn.close()
phone.close()

clicent

import socket
phone = socket.socket()
phone.connect(("127.0.0.1", 8080))
while 1:
    try:
        data = input("请输入>>>")
        if not data:
            print("输入内容不为空！")
            continue
        phone.send(data.encode("utf-8"))
        if data.upper() == "Q":
            print("通信关闭！")
            break

        from_server_data = phone.recv(1024)
        if from_server_data.decode("utf-8").upper() == "Q":
            print("通信关闭！")
            break
        else:
            print(f"来自服务器的消息：{from_server_data.decode('utf-8')}")
    except Exception:
        print("通信关闭！")
        break
phone.close()

基于TCP协议的socket通信：实例：远程执行命令

bates：网络传输，文件存储时

server

import socket
phone = socket.socket()
phone.bind(("127.0.0.1", 8080))
phone.listen(3)
while 1:
    conn, addr = phone.accept()
    print(f"{addr}客户端连接了")
    while 1:
        try:
            from_client_data = conn.recv(1024)
            import subprocess
            obj = subprocess.Popen(from_client_data.decode('utf-8'),
                                   shell=True,
                                   stdout=subprocess.PIPE,
                                   stderr=subprocess.PIPE,
                                   )
            conn.send((obj.stdout.read() + obj.stderr.read()).upper())
        except Exception:
            print(f"{addr}客户端通信关闭！")
            break
    conn.close()
phone.close()

client

import socket
phone = socket.socket()
phone.connect(("127.0.0.1", 8080))
while 1:
    try:
        data = input("请输入>>>")
        if not data:
            print("输入内容不为空！")
            continue
        phone.send(data.encode("utf-8"))
        if data.upper() == "Q":
            print("通信关闭！")
            break

        from_server_data = phone.recv(1024)
        print(from_server_data.decode('gbk'))
    except Exception:
        print("通信关闭！")
        break
phone.close()

粘包现象

为什么出现粘包？

只有TCP有粘包现象，UDP永远不会粘包！

操作系统的缓冲区

• 为什么存在缓冲区
  • 暂时存储一些数据
  • 缓冲区存在如果你的网络波动，保证数据的收发稳定，匀速

缺点：造成了粘包现象之一

什么情况下出现粘包？

• 出现粘包的情况

  • 客户端发送了一段数据过大，服务端只收了一部分，服务端下次再收的时候还是从缓冲区拿上次遗留的数据，产生粘包

  server

  # import socket
  # import subprocess
  # phone = socket.socket()
  # phone.bind(('127.0.0.1',8848))
  # phone.listen(2)
  # # listen: 2 允许有两个客户端加到半链接池，超过两个则会报错
  
  # while 1:
  #     conn,addr = phone.accept()  # 等待客户端链接我,阻塞状态中
  #     # print(f'链接来了: {conn,addr}')
  #     while 1:
  #         try:
  #             from_client_data = conn.recv(1024)  # 最多接受1024字节
  #             if from_client_data.upper() == b'Q':
  #                 print('客户端正常退出聊天了')
  #                 break
  #             obj = subprocess.Popen(from_client_data.decode('utf-8'),
  #                                    shell=True,
  #                                    stdout=subprocess.PIPE,
  #                                    stderr=subprocess.PIPE,
  #                                    )
  #             result = obj.stdout.read() + obj.stderr.read()
  #             print(f'总字节数：{len(result)}')
  #             conn.send(result)
  #         except ConnectionResetError:
  #             print('客户端链接中断了')
  #             break
  #     conn.close()
  # phone.close()
  

  client

  # import socket
  #
  # phone = socket.socket()
  #
  # phone.connect(('127.0.0.1',8848))
  # while 1:
  
  # to_server_data = input('>>>输入q或者Q退出').strip().encode('utf-8')
  
  # if not to_server_data:
  
  # # 服务端如果接受到了空的内容，服务端就会一直阻塞中，所以无论哪一端发送内容时，都不能为空发送
  
  # print('发送内容不能为空')
  
  # continue
  
  # phone.send(to_server_data)
  
  # if to_server_data.upper() == b'Q':
  
  # break
  
  # from_server_data = phone.recv(300)  # 最多接受1024字节
  
  # # print(f'{from_server_data.decode("gbk")}')
  
  # print(len(from_server_data))
  
  # phone.close()
  

  • 连续短暂的send多次（数据量很小），你的数据会统一发送出去

server

2. 连续短暂的send多次(数据量很小),你的数据会统一发送出去.
# import socket


# phone = socket.socket()

#

# phone.bind(('127.0.0.1',8848))

#

# phone.listen(5)

#
#

# conn,addr = phone.accept()  # 等待客户端链接我,阻塞状态中

#

# from_client_data = conn.recv(1024)  # 最多接受1024字节

# print(f'来自客户端{addr}消息:{from_client_data.decode("utf-8")}')

# conn.close()

# phone.close()```python

client

  ```python
  # 2. 连续短暂的send多次(数据量很小),你的数据会统一发送出去.
  
  # import socket
  #
  # phone = socket.socket()
#
  # phone.connect(('127.0.0.1',8848))
#
  #
  # phone.send(b'he')
  # phone.send(b'll')
  # phone.send(b'o')
  #
  #
  # phone.close()
  # Nigle算法

深入研究收发

不一定是一收一发

• 发多次收一次

server

# 发多次收一次
# import socket
# phone = socket.socket()
# phone.bind(('127.0.0.1',8848))
# phone.listen(5)

# conn,addr = phone.accept()  # 等待客户端链接我,阻塞状态中
# from_client_data = conn.recv(1024)  # 最多接受1024字节
# print(f'来自客户端{addr}消息:{from_client_data.decode("utf-8")}')

# conn.close()
# phone.close()

client

# 发多次收一次
import socket
phone = socket.socket()
phone.connect(('127.0.0.1',8848))

phone.send(b'he')
phone.send(b'llo')
phone.close()
Nigle算法

• 发一次收多次

server

# 发一次收多次
# import socket
# phone = socket.socket()
# phone.bind(('127.0.0.1',8848))
# phone.listen(5)

# conn,addr = phone.accept()  # 等待客户端链接我,阻塞状态中
# from_client_data = conn.recv(3)  # 最多接受1024字节
# print(f'来自客户端{addr}消息:{from_client_data.decode("utf-8")}')
# from_client_data = conn.recv(3)  # 最多接受1024字节
# print(f'来自客户端{addr}消息:{from_client_data.decode("utf-8")}')
# from_client_data = conn.recv(3)  # 最多接受1024字节
# print(f'来自客户端{addr}消息:{from_client_data.decode("utf-8")}')
# from_client_data = conn.recv(3)  # 最多接受1024字节
# print(f'来自客户端{addr}消息:{from_client_data.decode("utf-8")}')

# conn.close()
# phone.close()

client

# 发一次收多次
# import socket
# phone = socket.socket()
# phone.connect(('127.0.0.1',8848))
# phone.send(b'hello world')
# phone.close()

如何解决粘包现象

解决粘包现象的思路：

服务端发一次数据 10000字节

客户端接收数据时，循环接收，每次（至多）接收1024个字节，直至将所有的字节全部接收完毕，将接收的数据拼接在一起，最后解码

• 遇到的问题1：recv的次数无法确定

  你发送总具体数据之前，先给我发一个总数据长度：5000个字节，如何在发送总数居

  客户端：先接收一个长度，5000个字节

  然后我再循环recv 控制循环的条件就是只要你接收的数据< 5000 一直接收

• 遇到的问题2：总数据的长度转化成的字节数不固定

你要将total_size int类型转化成bytes类型才可以发送

387 ---- > str(387) '387' ---->bytes b'387' 长度 3bytes

4185 ----> str(4185) '4185' ---->bytes b'4185' 长度 4bytes

18000------------------------------------------------------> 长度 5bytes

我们要解决：

将不固定长度的int类型转化成固定长度的bytes并且还可以翻转回来

struct模块

服务端：
import struct
total_size = len(result)
print(f'总字节数：{total_size}')
head_bytes = struct.pack('i',total_size)
conn.send(head_bytes)

conn.send(result)
total_size int类型

客户端：
head_bytes = phone.recv(4)
total_size = struct.unpack('i',head_bytes)[0]

low版解决粘包现象

server

import socket
import subprocess
import struct
phone = socket.socket()
phone.bind(("127.0.0.1", 8080))
phone.listen(3)
while 1:
    conn, addr = phone.accept()
    print(f"{addr}客户端连接了")
    while 1:
        try:
            from_client_data = conn.recv(1024)
            obj = subprocess.Popen(from_client_data.decode('utf-8'),
                                   shell=True,
                                   stdout=subprocess.PIPE,
                                   stderr=subprocess.PIPE,
                                   )
            data = obj.stdout.read() + obj.stderr.read()
            data_len = len(data)
            print(f"长度：{len(data)}")
            conn.send(struct.pack("i", data_len))
            conn.send(data)
        except Exception:
            print(f"{addr}客户端通信关闭！")
            break
    conn.close()
phone.close()

client

import socket
import struct
phone = socket.socket()
phone.connect(("127.0.0.1", 8080))
while 1:
    data = input("请输入>>>")
    if not data:
        print("输入内容不为空！")
        continue
    phone.send(data.encode("utf-8"))
    if data.upper() == "Q":
        print("通信关闭！")
        break

    data_deposit = b""
    data_head = phone.recv(4)
    data_new = struct.unpack("i", data_head)[0]
    while len(data_deposit) < data_new:
        data_deposit += phone.recv(1024)
    print(data_deposit.decode("gbk"))
phone.close()