socket编程

• setsocketopt(level, optname, value)

• getsocketopt(level, optname[, buflen])

• level一般是SOL_SOCKET, 表示使用socket选项

optname选项名	意义	返回值
SO_BINDTODEVICE	只在某个特殊网卡有效，可能不是移动设备	一个字符串返回设备名称，或默认为空
SO_BROADCAST	允许广播地址发送和接受信息包，只对UDP有效	布尔值
SO_DONTROUTE	禁止通过路由器和网关往外发送信息包，为了安全	布尔值
SO_KEEPALIVE	可以使TCP通信的信息包保持连续性。	布尔值
SO_OOBINLINE	把收到的不正常数据视为正常数据	布尔值
SO_REUSEADDR	当socket被关闭后，占用的端口号能马上重用，不再保留几分钟	布尔值
SO_TYPE	得到传输层协议，只用于get	整数

TCP和UDP编程的区别

客户端

#UDP
from socket import *
serverName = "hostname"
serverPort = 12000
clientSocket = socket(AF_NET,SOCK_DGRAM)
msg = raw_input("input sonething")
clientSocket.sendto(msg,(serverName,serverPort))
recvMsg, serverAddr = clientSocket.recvFrom(2048)
print(recvMsg)
clientSocket.close()

#TCP
from socket import *
serverName = "hostname"
serverPort = 12000
clientSocket = socket(AF_INET, SOCK_STREAM)
clientSocket.connect((serverName,serverPort))
msg = raw_input("input something")
clientSocket.send(msg)
recvMsg = clientSocket.recv(1024)
print(recvMsg)
clientSocket.close()

服务端

#UDP
from socket import *
serverPort = 12000
ServerSocket = socket(AF_INET, SOCK_DGRAM)
serverSocket.bind(("",serverPort))
print("The server is prepared")
while True:
    msg,clientAddr = serverSocket.recvfrom(2048)
    sendMsg = msg.upper()
    serverSocket.sendto(sendMsg,clientAddr)

#TCP
from socket import *
serverPort = 12000
ServerSocket = socket(AF_INET, SOCK_STREAM)
serverSocket.bind(("",serverPort))
serverSocket.listen(1)
print("The server is prepared")
while True:
    connnectedSocket,addr = serverSocket.accept()
    msg = connectedSocket.recv(1024)
    sendMsg = msg.upper()
    connectedSocket.close()

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Socket角度理解TCP连接

socket库允许访问本地C套接字库，通过控制网络层协议与传输层协议来控制如何发送数据

import socket
s = socket.socket(AF_INET, SOCK_STREAM)

网络层协议	传输层协议
AF_INET(IPv4)	SOCK_STEAM(TCP)
AF_INET(IPv6)	SOCK_DGRAM(UDP)
AF_UNIX(使用UNIX操作系统)

#客户端
import socket
host = "localhost"
port = 50007
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:#打开socket
    s.connect((host,port))                                  #连接至服务器，开始握手
    s.sendall(b'Hello World')
    data = s.recv(1024)
                                                            #with结束，调用close()开始挥手
print("receive:",repr(data))

#服务端
import socket
host = ""
port = 50007
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:#打开socket
    s.bind((host,port))                                     #绑定端口
    s.listen(1)                                             #每次只处理一个连接请求
    conn, addr = s.accept()                                 #当客户端发送请求，开始握手
    with conn:
        print("Connected by ",addr)
        while True:
            data = conn.recv(1024)
            if not data: break                             #客户端close()
            conn.sendall(data)
                                                           #内部with代码块，调用close()

建立TCP连接