04python 黏包(網路程式設計)
阿新 • • 發佈:2019-01-09
什麼叫做黏包?
先寫一個小補充:encode()函式、decode()函式:
encode() 是將資料型別轉換成bytes型別
decode()是將bytes型別轉換成其他型別
encode() 叫做編碼, decode( ) 叫做解碼
通過一段程式碼來引出黏包現象(基於TCP的網路通訊)
sever端19 1
import socket
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sk = socket.socket()
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sk .bind(('127.0.0.1', 8080))
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sk.listen()
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conn, addr = sk.accept()
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while True:
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cmd = input('>>>')
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conn.send((cmd.encode('utf-8'))) # 將輸入的資料轉換層(utf-8)的bytes型別,用於網路傳輸
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ret = conn.recv(1024).decode('utf-8') # 將接收到的資料(utf-8)的bytes型別資料,解碼成本身的資料型別
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print(ret)
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conn.close()
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sk.close()
client端
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import socket
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import subprocess
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sk = socket.socket()
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sk.connect(('127.0.0.1', 8080))
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while True:
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cmd = sk.recv(1024).decode('utf-8')
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ret = subprocess.Popen(cmd, shell=True,
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stdout=subprocess.PIPE,
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stderr=subprocess.PIPE)
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std_out = 'stdout :' + (ret.stdout.read()).decode('gbk')
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std_err = 'stderr :' + (ret.stderr.read()).decode('gbk')
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print(std_out)
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print(std_err)
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sk.send(std_out.encode('utf-8'))
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sk.send(std_err.encode('utf-8'))
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sk.close()
仔細觀察控制檯這個時候會發現基於TCP連線從server端傳送指令時,會接收一些並不完整的資料,在一次從server端傳送指令時,client端會發送上一次斷點的資料給server端,我們把這種現象叫做黏包!
基於UDP協議的黏包現象(ps:不存在)
udp_server20 1
import socket
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sk = socket.socket(type=socket.SOCK_DGRAM)
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sk.bind(('127.0.0.1', 8091))
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msg, addr = sk.recvfrom(1024)
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while True:
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cmd = input('>>>')
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if cmd == 'q':
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break
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sk.sendto(cmd.encode('utf-8'), addr)
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msg, addr = sk.recvfrom(1024) # 兩次傳送、兩次接收
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print(msg.decode('utf-8'))
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msg, addr = sk.recvfrom(1024)
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print(msg.decode('utf-8'))
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sk.close()
udp_client
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import socket
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import subprocess
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sk = socket.socket(type=socket.SOCK_DGRAM)
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addr = ('127.0.0.1', 8091)
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sk.sendto('吃了嗎?'.encode('utf-8'), addr)
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while True:
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cmd, addr = sk.recvfrom(1024)
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ret = subprocess.Popen(cmd.decode('gbk'), # 這裡轉碼與解碼的方式前後不一致,但傳送過來的資料是英文。所以無妨!
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shell=True,
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stdout=subprocess.PIPE,
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stderr=subprocess.PIPE
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)
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std_out = 'stdout: ' + (ret.stdout.read()).decode('gbk')
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std_err = 'stderr: ' + (ret.stderr.read()).decode('gbk')
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print(std_out)
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print(std_err)
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sk.sendto(std_out.encode('utf-8'), addr)
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sk.sendto(std_err.encode('utf-8'), addr)
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sk.close()
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