Exercise 1: Change the socket program socket1.py to prompt the user
for the URL so it can read any web page. You can use split('/') to
break the URL into its component parts so you can extract the host
name for the socket connect call. Add error checking using try and
except to handle the condition where the user enters an improperly
formatted or non-existent URL.
import socket
url = input('name:')
word = url.split('/')
host = word[2]
print(host)
try:
mysock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
mysock.connect(('host', 80))
mysock.send(('GET '+url+' HTTP/1.0\r\n\r\n').encode())
except:
print ("Try your best")
while True:
data = mysock.recv(512)
if len(data) < 1:
break
print(data.decode(),end='')
mysock.close()
OSError: [WinError 10057] A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied
would you please help me? why code return me this error? how can I resolve it without any other new function?
mysock.connect(('host', 80))
Should be
mysock.connect((host, 80))
Related
I have been trying to create a messaging service in python using sockets. I have written the code to host two connections and allow one to send messages to the other using username and host_addr.
But every time I try to connect the second client and send a message from the first getting the following error.
ConnectionResetError: [Errno 54] Connection reset by peer
Server.py
import socket
import _thread as thread
HOST = "127.0.0.1" # Standard loopback interface address (localhost)
PORT = 1237 # Port to listen on (non-privileged ports are > 1023)
user_mapping = {}
def on_new_client(conn, addr):
data = conn.recv(1024)
data = data.decode()
print(data)
print(user_mapping)
if data[:8] == "username":
user_mapping[data[9:]] = (addr, data[9:])
elif data[0] == "#":
for i in user_mapping.values():
if i[0] == addr:
from_user = i[1]
else:
str = "user not found"
conn.sendto(str.encode(), addr)
str = "%s:%s" % (from_user, data[data.find(":") + 1:])
conn.sendto(str.encode(), user_mapping[data[1:data.find(":")](0)])
else:
pass
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(10)
while True:
conn, addr = s.accept()
thread.start_new_thread(on_new_client,(conn,addr))
s.close()
Client.py
import socket
HOST = "127.0.0.1" # The server's hostname or IP address
PORT = 1237 # The port used by the server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
username = input("Enter user name")
str = "username: %s" % username
s.send(str.encode())
while True:
message = input(username+">")
s.send(message.encode())
data = s.recv(1024)
print(data)
Was hoping some would could answer why this is happening and guide me to any good links where there is Information on creating a messaging service in python.
Client is sending 2 messages and then receiving one.
But server just listen once and then send one or two packages.
Chronologically:
Client sends a package, and server reads it.
Then both client and server try to send a package. Both packages that won't meet a listening peer.
Then client try to receive a package, but server won't send (he already sent it before) or it may send but its too late because communication is already broken.
Concepts you may implement always:
If one talk, another one may listen.
If a package is mean to be sent, it shall be sent anyway. Dont let a 'if' statment that send package when at 'else' that does not (or viceversa).
==== EDIT ====
About solution:
You need to work with paralel loops.
Take a look at this code https://www.neuralnine.com/tcp-chat-in-python/
He uses two threads on client, one for keep listening for new server updates (messages for other people) and another one to wait input from user.
I am writing a very simple Python socket program to read an HTML body from the server. If I create a HelloWorld.html file and open it with the designated host and port, I can open the file in my browser with the following server and read the message in the HTML file. However, I am having trouble reading in the same information from my client.
Server
from socket import *
serverSocket = socket(AF_INET,SOCK_STREAM)
host = '127.0.0.1'
port = 6789
serverSocket.bind((host,port))
serverSocket.listen(5)
print("server started...")
(connectionSocket, addr) = serverSocket.accept()
try:
message = connectionSocket.recv(1024).decode()
filename = message.split()[1]
f = open(filename[1:]) # Throws IOError if file not found
print(filename, "found")
connectionSocket.send("HTTP/1.0 200 OK\r\n".encode())
connectionSocket.send("Content-Type: text/html\r\n".encode())
connectionSocket.send(message.encode())
outputdata = f.read()
for i in range(0, len(outputdata)):
connectionSocket.send(outputdata[i].encode())
connectionSocket.send("\r\n".encode())
connectionSocket.close()
print(filename, "delivered")
except IOError:
print(filename, "NOT found")
connectionSocket.send('HTTP/1.0 404 NOT FOUND\r\n')
connectionSocket.close()
print("file not found message delivered")
serverSocket.close()
print("server closed...")
My server seems to be working. However, when my client tries to send the HTML object path to the socket and have the server read it, it does not seem to be picking up the message. I have just started socket programming in Python and I am trying to understand how the server receives the message from the socket. My initial thought was if I send the path of the HTML object (located in same directory as client and server) to the socket, the server should be able to read that information, open it, and return the information to the client.
Client
from socket import *
import sys
client = socket(AF_INET, SOCK_STREAM)
host = sys.argv[1]
port = sys.argv[2]
obj = sys.argv[3]
port = int(port)
client.connect((host, port))
print(client.getsockname())
request = obj
client.send("hello".encode())
client.send(request.encode())
s = client.recv(1024).decode()
print(s)
For my client, I accept the host,port, and the path to the HTML from a commandline argument and establish a connection.
When I run the browser for my HTML file with the url http://127.0.0.1:6789/HelloWorld.html, the server responds well. However, when I run the server and run the client with the command py capClient.py 127.0.0.1 6789 HelloWorld.html on the shell, it returns the filename = message.split()[1] IndexError: list index out of range error. I am assuming that this problem is coming from the server not being able to split the message coming in from the connectionSocket as an acceptable HTML object path.
What are some tips on modifying the client code to receive HTML file from servers?
This trouble is because you await message string is 'hello HelloWorld.html', but it is 'helloHelloWorld.html' and split() get you list ['helloHelloWorld.html'] where index 1 not exists.
f = open(filename[1:])
# must be replaced with [1:] give you a list, not string
f = open(filename)
# there needs encode()
connectionSocket.send('HTTP/1.0 404 NOT FOUND\r\n'.encode())
I have a homework assignment which involves implementing a proxy cache server in Python. The idea is to write the web pages I access to temporary files on my local machine and then access them as requests come in if they are stored. Right now the code looks like this:
from socket import *
import sys
def main():
#Create a server socket, bind it to a port and start listening
tcpSerSock = socket(AF_INET, SOCK_STREAM) #Initializing socket
tcpSerSock.bind(("", 8030)) #Binding socket to port
tcpSerSock.listen(5) #Listening for page requests
while True:
#Start receiving data from the client
print 'Ready to serve...'
tcpCliSock, addr = tcpSerSock.accept()
print 'Received a connection from:', addr
message = tcpCliSock.recv(1024)
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 whether the file exists 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")
for data in outputdata:
tcpCliSock.send(data)
print 'Read from cache'
except IOError: #Error handling for file not found in cache
if fileExist == "false":
c = socket(AF_INET, SOCK_STREAM) #Create a socket on the proxyserver
hostn = filename.replace("www.","",1)
print hostn
try:
c.connect((hostn, 80)) #https://docs.python.org/2/library/socket.html
# 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\r\n")
# Read the response into buffer
buffr = fileobj.readlines()
# 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")
for data in buffr:
tmpFile.write(data)
tcpCliSock.send(data)
except:
print "Illegal request"
else: #File not found
print "404: File Not Found"
tcpCliSock.close() #Close the client and the server sockets
main()
To test my code, I run the proxy cache on my localhost and set my browser proxy settings accordingly like so
However, when I run this code and try to access google with Chrome, I'm greeting with an error page saying err_empty_response.
Stepping through the code with the debugger made me realizing it's failing on this line
c.connect((hostn, 80))
and I have no idea why. Any help would be greatly appreciated.
P.S. I'm testing this with Google Chrome, Python 2.7, and Windows 10
You cannot use a name on connect. Connect expects an IP address to connect to.
You can get the socket information you need to build the connection using getaddrinfo(). In my pure-python-whois package I used the following code to create a connection:
def _openconn(self, server, timeout, port=None):
port = port if port else 'nicname'
try:
for srv in socket.getaddrinfo(server, port, socket.AF_UNSPEC, socket.SOCK_STREAM, 0, socket.AI_ADDRCONFIG):
af, socktype, proto, _, sa = srv
try:
c = socket.socket(af, socktype, proto)
except socket.error:
c = None
continue
try:
if self.source_addr:
c.bind(self.source_addr)
c.settimeout(timeout)
c.connect(sa)
except socket.error:
c.close()
c = None
continue
break
except socket.gaierror:
return False
return c
Note that this isn't great code because the loop is actually there for nothing instead of using the different alternatives. You should only break the loop once you have established a connection. However, this should work as an illustration for using getaddrinfo()
EDIT:
You are also not cleaning your hostname correctly. I get /www.example.com/ when I try accessing http://www.example.com/ which obviously won't resolve. I'd suggest that you use a regular expression to get the file name for your cache.
I can't seem to figure out why my code can't handle the exception of reporting an error if my web server does not contain a file. In the directory of my server I have the code for it and HelloWorld.html. For other files it should report an error. I'm looking through my code and it would seem that it is reading any file and just saying that its contents are blank without actually throwing an error that the file is not on the server. What is going on here?
#Tasks: Create a socket, bind to a specific address and port, send and receive an HTTP packet.
#Description: Web server should handle one HTTP request at a time. So the serve closes its TCP connection after response.
#Accept and parse the HTTP request, get the requested file from the server (i.e. HelloWorld.html), create a response
#message with the requested file and header lines, then send the response to the client.
#Error handling: If file not found then send HTTP "404 Not Found" Message back to client.
#import socket module: here we are using a low-level networking class from Python
from socket import *
#create the socket that belongs to the server.
#AF_INTET represents the address families and protocols.
#SOCK_STREAM represents the socket type
serverSocket = socket(AF_INET, SOCK_STREAM)
#Prepare a server socket
#Define variable for serverPort; we'll use the one in the helper page of the book
serverPort = 51350
#Define host address
serverHost = ''
#Bind the socket to the local host machine address and port
serverSocket.bind((serverHost, serverPort))
#Listen for TCP connections from the client
serverSocket.listen(1)
#Verify setup for receiving
print 'Server is ready to receive'
while True:
#Establish the connection
print 'Ready to serve...'
#When the server receive a request from the client it must establish a new connectionSocket and begin taking in the data.
connectionSocket, addr = serverSocket.accept()
try:
#Take data from connectionSocket and place in message.
#.recvfrom doesn't work because it expects data and return address variables.
message = connectionSocket.recv(1024)
#uncomment for header information
#print message
#parse the message
filename = message.split()[1]
f = open(filename[1:])
outputdata = f.read();
#Send one HTTP header line into socket
connectionSocket.send('HTTP/1.1 200 OK\r\n\r\n')
#Send the content of the requested file to the client
for i in range(0, len(outputdata)):
connectionSocket.send(outputdata[i])
connectionSocket.close()
except IOError:
#Send response message for file not found
connectionSocket.send('404 Not Found')
connectionSocket.close()
#Close client socket
serverSocket.close()
Perhaps you need "HTTP/1.1 404 Not Found\r\n\r\n" instead of "404 Not Found".
Also, you seem to close serverSocket within the loop, thus next accept() fails.
I am trying to connect to URL https://www.ssehl.co.uk/HALO/publicLogon.do in Python.
The simple solution using requests fails:
import requests
r = requests.get('https://www.ssehl.co.uk/HALO/publicLogon.do')
print r.text
with error
File "c:\Python27\lib\site-packages\requests\adapters.py", line 327, in send
raise ConnectionError(e)
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='www.ssehl.co.uk', port=443): Max retries exceeded with url: /HALO/publicLogon.do (Caused by <class 'httplib.BadStatusLine'>: '')
so I tried to get the raw response from the server using library socket:
import socket #for sockets
import sys #for exit
#create an INET, STREAMing socket
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error:
print 'Failed to create socket'
sys.exit()
print 'Socket Created'
host = 'www.ssehl.co.uk';
port = 443;
try:
remote_ip = socket.gethostbyname(host)
except socket.gaierror:
#could not resolve
print 'Hostname could not be resolved. Exiting'
sys.exit()
#Connect to remote server
s.connect((remote_ip , port))
print 'Socket Connected to ' + host + ' on ip ' + remote_ip
#Send some data to remote server
message = "GET /HALO/publicLogon.do HTTP/1.1\r\n\r\n"
try :
#Set the whole string
s.sendall(message)
except socket.error:
#Send failed
print 'Send failed'
sys.exit()
print 'Message send successfully'
#Now receive data
reply = s.recv(4096)
print reply
will output:
Socket Created
Socket Connected to www.ssehl.co.uk on ip 161.12.7.194
Message send successfully
Reply:
after reply there is some garbage which I can't paste, however this is a sublime console screenshot:
Screenshot
Is there any way to get a 200 response from the server, just like a browser?
For some reason when you use either Python's built in stuff (urllib2, requests, httplib) or even command line stuff (curl, wget) over https the server spazzes out and gives an erroneous response.
However when you request the page over regular http, it works fine, for example:
import urllib2
print urllib2.urlopen('http://www.ssehl.co.uk/HALO/publicLogon.do').getcode()
prints out
>> 200
My guess is that their servers are configured wrong and your browser somehow deals with it silently.
It worked for me when I used port 80. Sooo:
port = 80;
There must be some error when using HTTPS servers thought Python...
Also, you are sending wrong request. You are not sending the hostname. Fixed request:
message = "GET /HALO/publicLogon.do HTTP/1.1\r\nHostname: %s\r\n\r\n"%host
So here is working code.
I think the problem exists, because port 443 is encrypted. And Python doesn't support encryption (probably).
You should use ssl.wrap_socket if you want support https.
See http://docs.python.org/2/library/ssl.html for details.