socket编程

socket编程，是一切web服务的祖宗，没有socket,就没有其他web服务，因为一切web服务都是在socket基础上进行加工处理。

那么下面直接上示例：

server端的代码

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import socket,os

sk = socket.socket()
sk.bind(('localhost',6969))
sk.listen(5)#这里的数字5表示最后可监听的客户端连接数，参数要写，不写可能会出错，而且数字不要太大
while True:
    print('等客户端连接。。。。')
    conn,addr = sk.accept()
    print('客户端连接进来了，准备收发数据了。。。')
    while True:
        data = conn.recv(1024)
        if not data:
            print('client has losted......')
            break
        #这里要用sendall来代替send，因为sendall会尝试发送所有数据，其实它内部是通过递归调用send
        #将所有内容发送出去。不过不是一次性发送，而是每次按照一定的大小发送。
        res = os.popen(data).read()
        conn.sendall(res)

sk.close()

client端的代码：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import socket

sk = socket.socket()
sk.connect(('localhost',6969))
while True:
    user_input  = raw_input('input>>>:').strip()
    if  len(user_input) == 0:continue
    sk.sendall(user_input.encode(encoding='utf-8'))
    #这里的recv中的数值可以更改，但是接受的数据并不是以数值大小的绝对来接受，
    #当数值输入的很大，但接受数据还会按照一定的大小来接受。
    data = sk.recv(1024)
    print(data.decode())
sk.close()

 socket ssh实例：

1、服务端

import socket ,os,time
server = socket.socket()
server.bind(('localhost',9999) )

server.listen()

while True:
    conn, addr = server.accept()
    print("new conn:",addr)
    while True:
        print("等待新指令")
        data = conn.recv(1024)
        if not data:
            print("客户端已断开")
            break
        print("执行指令:",data)
        cmd_res = os.popen(data.decode()).read() #接受字符串，执行结果也是字符串
        print("before send",len(cmd_res))
        if len(cmd_res) ==0:
            cmd_res = "cmd has no output..."

        conn.send( str(len(cmd_res.encode())).encode("utf-8")    )     #先发大小给客户端
        conn.recv(1024) #这命令主要为了防止粘包
        conn.send(cmd_res.encode("utf-8"))
        print("send done")
server.close()

2、客户端:

import socket
client = socket.socket()

#client.connect(('192.168.16.200',9999))
client.connect(('localhost',9999))

while True:
    cmd = input(">>:").strip()
    if len(cmd) == 0: continue
    client.send(cmd.encode("utf-8"))
    cmd_res_size = client.recv(1024) ##接受命令结果的长度
    print("命令结果大小:",cmd_res_size)
	client.send('准备接受数据'.encode('utf-8')) #这命令主要为了防止粘包
    received_size = 0
    received_data = b''
    while received_size < int(cmd_res_size.decode()) :
        data = client.recv(1024)
        received_size += len(data) #每次收到的有可能小于1024，所以必须用len判断
        #print(data.decode())
        received_data += data
    else:
        print("cmd res receive done...",received_size)
        print(received_data.decode())


client.close()

socket FTP实例：

1、服务端：

import hashlib
import socket ,os,time
server = socket.socket()
server.bind(('0.0.0.0',9999) )
server.listen()
while True:
    conn, addr = server.accept()
    print("new conn:",addr)
    while True:
        print("等待新指令")
        data = conn.recv(1024)
        if not data:
            print("客户端已断开")
            break
        cmd,filename = data.decode().split()
        print(filename)
        if os.path.isfile(filename):
           f = open(filename,"rb")
           m = hashlib.md5()
           file_size = os.stat(filename).st_size
           conn.send( str(file_size).encode() ) #send file size
           conn.recv(1024) #wait for ack
           for line in f:
              m.update(line)
              conn.send(line)
           print("file md5", m.hexdigest())
           f.close()
           conn.send(m.hexdigest().encode()) #send md5
        print("send done")

server.close()

2、客户端：

import socket
import hashlib

client = socket.socket()

client.connect(('localhost', 9999))

while True:
    cmd = input(">>:").strip()
    if len(cmd) == 0: continue
    if cmd.startswith("get"):
        client.send(cmd.encode())
        server_response = client.recv(1024)
        print("servr response:", server_response)
        client.send(b"ready to recv file")
        file_total_size = int(server_response.decode())
        received_size = 0
        filename = cmd.split()[1]
        f = open(filename + ".new", "wb")
        m = hashlib.md5()

        while received_size < file_total_size:
            if file_total_size - received_size > 1024:  # 要收不止一次
                size = 1024
            else:  # 最后一次了，剩多少收多少
                size = file_total_size - received_size
                print("last receive:", size)

            data = client.recv(size)
            received_size += len(data)
            m.update(data)
            f.write(data)
            # print(file_total_size,received_size)
        else:
            new_file_md5 = m.hexdigest()
            print("file recv done", received_size, file_total_size)
            f.close()
        server_file_md5 = client.recv(1024)
        print("server file md5:", server_file_md5)
        print("client file md5:", new_file_md5)

client.close()