28 粘包

一粘包现象:

粘包1:连续的小包,会被优化机制给合并

粘包2:服务端一次性无法完全就收完客户端发送的数据,第二再次接收的时候,会接收到第一次遗留的内容

 

解决粘包的方案:

方案1:先告诉客户端,数据信息的长度,然后等客户端确认之后,再发送真实内容

方案2:通过struct模块,将要发送的真实数据的长度进行打包,打包成4个字节,和真实数据一起一次性发送个客户端.

   客户端取出前4个字节,通过struct解包获得后面真实数据的长度,根据这个长度再进行数据的接受

黏包现象只发生在tcp协议中：

1.从表面上看，黏包问题主要是因为发送方和接收方的缓存机制、tcp协议面向流通信的特点。

2.实际上，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。

 

二.struct  打包模块

import struct

num = 12235667
num_str = struct.pack('i',num)
print(num_str) #b'\x0c\x00\x00\x00'
print(len(num_str))

a = struct.unpack('i',num_str)[0] #12235667

print(a) #(12235667,) #

#服务端
import socket

server = socket.socket()
ip_port = ('127.0.0.1',8001)

server.bind(ip_port)
server.listen()

conn,addr = server.accept()

from_client_msg1 = conn.recv(1024).decode('utf-8')
from_client_msg2 = conn.recv(1024).decode('utf-8')

print('from_client_msg1>>>',from_client_msg1)
print('from_client_msg2>>>',from_client_msg2)

#客户端
import json
import socket

client = socket.socket()
ip_port = ('127.0.0.1',8001)
client.connect(ip_port)

client.send(b'12')
client.send(b'22')

#服务端
import socket
import subprocess
server = socket.socket()
ip_port = ('127.0.0.1',8001)
server.bind(ip_port)
server.listen()
conn,addr = server.accept()
while 1:
    from_client_cmd = conn.recv(1024).decode('utf-8')

    sub_obj = subprocess.Popen(
        from_client_cmd,
        shell=True,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
    )
    #subprocess对象.read 得到的结果是bytes类型的
    cmd_res = sub_obj.stdout.read()
    print('结果长度>>>',len(cmd_res))
    conn.send(cmd_res)

#客户端
import json
import socket

client = socket.socket()
ip_port = ('127.0.0.1',8001)
client.connect(ip_port)



while 1:
    client_cmd = input('请输入系统指令>>>')
    client.send(client_cmd.encode('utf-8'))

    from_server_result = client.recv(1024)

    print(from_server_result.decode('gbk'))

　　

import socket
import subprocess
server = socket.socket()
ip_port = ('127.0.0.1',8001)
data_full_len = 0 #统计发送数据的长度
server.bind(ip_port)
server.listen()
conn,addr = server.accept()
while 1:
    from_client_cmd = conn.recv(1024).decode('utf-8')

    sub_obj = subprocess.Popen(
        from_client_cmd,
        shell=True,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
    )
    #subprocess对象.read 得到的结果是bytes类型的
    cmd_res = sub_obj.stdout.read()
    data_len = len(cmd_res)  #总数据长度
    data_len_str = str(data_len)
    print('结果长度>>>',data_len)

    conn.send(data_len_str.encode('utf-8'))
    client_stutas = conn.recv(1024).decode('utf-8')

    if client_stutas == 'ok':
        #发送真实数据
        while data_full_len < data_len:
            every_send_data = cmd_res[data_full_len:data_full_len + 1024]
            every_send_datalen = len(every_send_data)
            conn.send(every_send_data)
            data_full_len += 1024

    else:
        print('客户端长度信息没有收到')

import json
import socket

client = socket.socket()
ip_port = ('127.0.0.1',8001)
client.connect(ip_port)
all_recv_len = 0
all_data_byte = b''

while 1:
    client_cmd = input('请输入系统指令>>>')
    client.send(client_cmd.encode('utf-8'))
    from_server_datalen = client.recv(1024).decode('utf-8')
    all_data_len = int(from_server_datalen)  #服务端发送的总数据长度

    client.send(b'ok')

    while all_recv_len < all_data_len:

        from_server_result = client.recv(1024)
        every_recv_len = len(from_server_result) #每次接受的数据长度
        all_recv_len += every_recv_len
        all_data_byte += from_server_result


    print(all_data_byte.decode('gbk'))

import socket
import subprocess
import struct
server = socket.socket()
ip_port = ('127.0.0.1',8001)
data_full_len = 0 #统计发送数据的长度
server.bind(ip_port)
server.listen()
conn,addr = server.accept()
while 1:
    from_client_cmd = conn.recv(1024).decode('utf-8')

    sub_obj = subprocess.Popen(
        from_client_cmd,
        shell=True,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
    )
    #subprocess对象.read 得到的结果是bytes类型的
    cmd_res = sub_obj.stdout.read()
    data_len = len(cmd_res)  #总数据长度
    data_len_str = str(data_len)
    print('结果长度>>>',data_len)

    #将真实数据长度打包成4个字节的数据
    struct_data_len = struct.pack('i',data_len)

    conn.send(struct_data_len + cmd_res)

import json
import socket
import struct
client = socket.socket()
ip_port = ('127.0.0.1',8001)
client.connect(ip_port)
all_recv_len = 0
all_data_byte = b''

while 1:
    client_cmd = input('请输入系统指令>>>')
    client.send(client_cmd.encode('utf-8'))
    #先接收4个字节,这4个字节是真实数据长度加工成的
    recv_data_len = client.recv(4)
    #将4个字节长度的数据,解包成后面真实数据的长度
    real_data_len = struct.unpack('i',recv_data_len)[0]

    print(real_data_len)

    server_result = client.recv(real_data_len)

    print(server_result.decode('gbk'))

合法性连接

from socket import *
import hmac,os

secret_key=b'Jedan has a big key!'
def conn_auth(conn):
    '''
    验证客户端到服务器的链接
    :param conn:
    :return:
    '''
    msg=conn.recv(32)
    h=hmac.new(secret_key,msg)
    digest=h.digest()
    conn.sendall(digest)

def client_handler(ip_port,bufsize=1024):
    tcp_socket_client=socket(AF_INET,SOCK_STREAM)
    tcp_socket_client.connect(ip_port)

    conn_auth(tcp_socket_client)

    while True:
        data=input('>>: ').strip()
        if not data:continue
        if data == 'quit':break

        tcp_socket_client.sendall(data.encode('utf-8'))
        respone=tcp_socket_client.recv(bufsize)
        print(respone.decode('utf-8'))
    tcp_socket_client.close()

if __name__ == '__main__':
    ip_port=('127.0.0.1',9999)
    bufsize=1024
    client_handler(ip_port,bufsize)

from socket import *
import hmac,os

secret_key=b'Jedan has a big key!'
def conn_auth(conn):
    '''
    认证客户端链接
    :param conn:
    :return:
    '''
    print('开始验证新链接的合法性')
    msg=os.urandom(32)#生成一个32字节的随机字符串
    conn.sendall(msg)
    h=hmac.new(secret_key,msg)
    digest=h.digest()
    respone=conn.recv(len(digest))
    return hmac.compare_digest(respone,digest)

def data_handler(conn,bufsize=1024):
    if not conn_auth(conn):
        print('该链接不合法,关闭')
        conn.close()
        return
    print('链接合法,开始通信')
    while True:
        data=conn.recv(bufsize)
        if not data:break
        conn.sendall(data.upper())

def server_handler(ip_port,bufsize,backlog=5):
    '''
    只处理链接
    :param ip_port:
    :return:
    '''
    tcp_socket_server=socket(AF_INET,SOCK_STREAM)
    tcp_socket_server.bind(ip_port)
    tcp_socket_server.listen(backlog)
    while True:
        conn,addr=tcp_socket_server.accept()
        print('新连接[%s:%s]' %(addr[0],addr[1]))
        data_handler(conn,bufsize)

if __name__ == '__main__':
    ip_port=('127.0.0.1',9999)
    bufsize=1024
    server_handler(ip_port,bufsize)

获取缓存区大小

import socket
from socket import SOL_SOCKET,SO_REUSEADDR,SO_SNDBUF,SO_RCVBUF
sk = socket.socket(type=socket.SOCK_DGRAM)
# sk.setsockopt(SOL_SOCKET,SO_RCVBUF,80*1024)
sk.bind(('127.0.0.1',8090))
print('>>>>', (sk.getsockopt(SOL_SOCKET, SO_SNDBUF))/1024)
print('>>>>', sk.getsockopt(SOL_SOCKET, SO_RCVBUF))