对于编程练习(来自计算机网络:Kurose 和 Ross 的自顶向下方法(第 6 版)),我们正在尝试用 python 开发一个简单的代理服务器。
我们得到了以下代码,只要它说#Fill in start. ... #Fill in end.
是我们需要编写代码的地方。我的具体问题和尝试将在这个原始片段下方。
我们需要使用以下命令启动 python 服务器:python proxyserver.py [server_ip]
然后导航到localhost:8888/google.com
它应该在我们完成后工作。
from socket import *
import sys
if len(sys.argv) <= 1:
print 'Usage : "python ProxyServer.py server_ip"\n[server_ip : It is the IP Address Of Proxy Server'
sys.exit(2)
# Create a server socket, bind it to a port and start listening
tcpSerSock = socket(AF_INET, SOCK_STREAM)
# Fill in start.
# Fill in end.
while 1:
# Strat receiving data from the client
print 'Ready to serve...'
tcpCliSock, addr = tcpSerSock.accept()
print 'Received a connection from:', addr
message = # Fill in start. # Fill in end. print message
# Extract the filename from the given message print message.split()[1]
filename = message.split()[1].partition("/")[2] print filename
fileExist = "false"
filetouse = "/" + filename
print filetouse
try:
# Check wether the file exist in the cache
f = open(filetouse[1:], "r")
outputdata = f.readlines()
fileExist = "true"
# ProxyServer finds a cache hit and generates a response message
tcpCliSock.send("HTTP/1.0 200 OK\r\n")
tcpCliSock.send("Content-Type:text/html\r\n")
# Fill in start.
# Fill in end.
print 'Read from cache'
# Error handling for file not found in cache
except IOError:
if fileExist == "false":
# Create a socket on the proxyserver
c = # Fill in start. # Fill in end.
hostn = filename.replace("www.","",1)
print hostn
try:
# Connect to the socket to port 80
# Fill in start.
# Fill in end.
# Create a temporary file on this socket and ask port 80 for the file requested by the client
fileobj = c.makefile('r', 0)
fileobj.write("GET "+"http://" + filename + "HTTP/1.0\n\n")
# Read the response into buffer
# Fill in start.
# Fill in end.
# Create a new file in the cache for the requested file.
# Also send the response in the buffer to client socket and the corresponding file in the cache
tmpFile = open("./" + filename,"wb")
# Fill in start.
# Fill in end.
except:
print "Illegal request"
else:
# HTTP response message for file not found
# Fill in start.
# Fill in end.
# Close the client and the server sockets
tcpCliSock.close()
# Fill in start.
# Fill in end.
它在哪里说:
# Create a socket on the proxyserver
c = # Fill in start. # Fill in end.
我试过:
c = socket(AF_INET, SOCK_STREAM)
这似乎是您创建套接字的方式,然后为了连接到主机的端口 80,我有:
c.connect((hostn, 80))
在这里,根据我的一些本地打印语句hostn
是正确的。google.com
我要填写的下一部分说,#Read response into buffer
但我真的不明白这意味着什么。我认为它与fileobj
上面创建的内容有关。
在此先感谢,如果我错过了任何我应该添加的内容,请告诉我。
更新
我当前的代码可以在这里找到,看看我一直在尝试什么:
https://github.com/ardavis/Computer-Networks/blob/master/Lab%203/ProxyServer.py