Socket编程学习-基础操作

socket的基本操作

可参考，https://blog.csdn.net/sinat_36645384/article/details/79128137

核心问题1-UDP与TCP的区别

1、TCP是基于连接的基础上，而UDP是不需要的。这就导致了，TCP一般用recv获取数据，而UDP用recvfrom获取数据和地址。因为TCP是基于连接的基础上，所以获取地址就是多此一举了。

创建socket

try:
    #create an AF_INET, STREAM socket (TCP)
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error as msg:
    print('Failed to create socket. Error code: ' + str(msg[0]) + ' , Error message : ' + msg[1])
    sys.exit()

注意，这里的socket.SOCK_STREAM指的是TCP。UDP用SOCK_DGRAM

连接指定ip

import socket   #for sockets
import sys  #for exit

try:
    #create an AF_INET, STREAM socket (TCP)
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error as msg:
    print('Failed to create socket. Error code: ' + str(msg[0]) + ' , Error message : ' + msg[1])
    sys.exit();

print('Socket Created')

host = 'www.oschina.net'
port = 80

try:
    remote_ip = socket.gethostbyname( host )

except socket.gaierror:
    #could not resolve
    print('Hostname could not be resolved. Exiting')
    sys.exit()

print('Ip address of ' + host + ' is ' + remote_ip)

#Connect to remote server
s.connect((remote_ip , port))

print('Socket Connected to ' + host + ' on ip ' + remote_ip)

Socket Created
Ip address of www.oschina.net is 180.97.125.228
Socket Connected to www.oschina.net on ip 180.97.125.228

发送数据

#Send some data to remote server
message = "GET / HTTP/1.1\r\n\r\n"

try :
    #Set the whole string
    s.sendall(message)
except socket.error:
    #Send failed
    print('Send failed')
    sys.exit()

print('Message send successfully')

报错：

s.sendall(message)

TypeError: a bytes-like object is required, not ‘str’

socket.socket def sendall(self,
data: bytes,
flags: int = …) -> None
< Python 3.7 (pythonProject) (2) >

于是：

message = "GET / HTTP/1.1\r\n\r\n".encode()

接受数据

#Now receive data
reply = s.recv(4096)

print reply

Socket Created
Ip address of www.oschina.net is 180.97.125.228
Socket Connected to www.oschina.net on ip 180.97.125.228
Message send successfully
b’HTTP/1.1 400 Bad Request\r\nServer: stgw/1.3.12_1.13.5\r\nDate: Sun, 23 Jan 2022 13:31:23 GMT\r\nContent-Type: text/html\r\nContent-Length: 179\r\nConnection: close\r\n\r\n\r\n400 Bad Request\r\n\r\n

400 Bad Request

\r\n

stgw/1.3.12_1.13.5 \r\n\r\n\r\n’

因为 reply: bytes = s.recv(4096)

于是：

reply = s.recv(4096).decode()

Socket Created
Ip address of www.oschina.net is 180.97.125.228
Socket Connected to www.oschina.net on ip 180.97.125.228
Message send successfully
HTTP/1.1 400 Bad Request
Server: stgw/1.3.12_1.13.5
Date: Sun, 23 Jan 2022 13:32:35 GMT
Content-Type: text/html
Content-Length: 179
Connection: close

400 Bad Request

stgw/1.3.12_1.13.5