第二章 网络编程
1、学习笔记
2、课后习题
答案是按照自己理解和查阅资料来的，不保证正确性。如由错误欢迎指出，谢谢
1. 套接字：A network socket is an endpoint of a connection across a computer network,Sockets are often represented internally as simple integers, which identify which connection to use.
套接字是网络通信的一个通信端点
有两种类型：
Stream Socket使用TCP协议的面向连接的socket ，SOCK_STREAM
Datagram Socket：使用UDP协议的无连接的socket， SOCK_DGRAM
2. Client/Server 构架
C/S构架
3. TCP和UDP套接字的工作原理
5.使用os.listdir("/etc")返回目录列表，os.curdir 表示当前的目录 .
os.name 返回操作系统信息
#!/usr/bin/python
#Filename : tsUserv.py
from socket import *
from time import ctime
import os
HOST = ""
PORT = 31080
BUFSIZ = 1024
ADDR = (HOST, PORT)
udpSerSock = socket(AF_INET, SOCK_DGRAM)
udpSerSock.bind(ADDR)
while True:
print "waiting for connection"
sysname = os.name
curdir = os.curdir
data, addr = udpSerSock.recvfrom(BUFSIZ)
dir = os.listdir("/etc")
udpSerSock.sendto("[%s] %s %s %s %s" %(ctime(),data,sysname,curdir,dir),addr)
print "received from and retrurned to :",addr
udpSerSock.close()
6.Daytime 服务,获取ssh服务的默认端口号返回给客户端
客户端使用的还是书中的例子，只是改了下服务端口
#!/usr/bin/python
# Filename : 2.6.ser.py
from socket import *
from time import ctime
HOST = "192.168.40.128"
PORT = 40026
ADDR = (HOST,PORT)
BUFSIZ = 1024
udpSerSock = socket(AF_INET,SOCK_DGRAM)
udpSerSock.bind(ADDR)
while True:
print "waiting for messages"
data,addr = udpSerSock.recvfrom(BUFSIZ)
portNum = getservbyname("telnet") #return an integer value ，and the function get the number from the file /etc/services.
# portNum = udpSerSock.getservbyname("ssh")
udpSerSock.sendto("%d"%portNum,addr)
# udpSerSock.sendto("%s"%portNum,addr)
print "received from and returned to:",addr
udpSerSock.close()
7. 半双工聊天
目前实现只能通过client 发起会话，无法从server发起会话，后续考虑如何实现从两侧都能主动发起会话。
server端代码：
#!/usr/bin/python
# Filename : 2.7_server.py
from socket import *
from time import ctime
HOST = "192.168.40.128"
PORT = 40027
BUFSIZ = 10240
ADDR = (HOST,PORT)
tcpSerSock = socket(AF_INET,SOCK_STREAM)
tcpSerSock.bind(ADDR)
tcpSerSock.listen(5)
print "waiting for messages"
while True:
tcpCliSock,addr = tcpSerSock.accept()
print "connected from :",addr
#这里可以实现从两端发起会话，但是会导致一段的消息在另外一端不能及时显示，必须输入要发送的消息之后才能看到上一条对方发送的消息。
# while True:
# data_local = raw_input("waiting for input>>>")
# if not data_local:
# continue
# tcpCliSock.send("[%s] %s"%(ctime(),data_local))
# print "send message to client successful,waiting for response"
while True:
data_remote = tcpCliSock.recv(BUFSIZ)
if not data_remote:
break
print "He says : ",data_remote
while True:
data_local = raw_input("waitint for input>>>")
if not data_local:
continue
tcpCliSock.send("[%s] %s"%(ctime(),data_local))
print "send message to client successful,waitinf for response"
break
tcpSerSock.close()
client端代码：
#!/usr/bin/python
# Filename : 2.7_client.py
from socket import *
from time import ctime
HOST = "192.168.40.128"
PORT = 40027
BUFSIZ = 10240
ADDR = (HOST,PORT)
tcpCliSock = socket(AF_INET,SOCK_STREAM)
tcpCliSock.connect(ADDR)
print "waiting for messages"
while True:
while True:
data_local = raw_input("waiting for input>>>")
if not data_local:
continue
tcpCliSock.send("[%s] %s"%(ctime(),data_local))
print "send message to server successful,waiting for response"
while True:
data_remote = tcpCliSock.recv(BUFSIZ)
if not data_remote:
break
print "He says : ",data_remote
break
tcpCliSock.close()
8.全双工聊天