Im having trouble getting my very basic and simple TCP Server to properly work with http requests. This is what I have so far
from socket import *
import sys
serverSocket = socket(AF_INET, SOCK_STREAM)
serverSocket.bind(('', 4567))
serverSocket.listen(1)
while True:
print('Ready to serve...')
connectionSocket, addr = serverSocket.accept()
print("connected from: ", addr)
try:
message = connectionSocket.recv(1024)
filename = message.split()[1]
f = open(filename[1:])
outputdata = f.read()
connectionSocket.send("HTTP/1.1 200 OK\r\n")
for i in range(0, len(outputdata)):
connectionSocket.send(outputdata[i].encode())
connectionSocket.send("\r\n".encode())
connectionSocket.close()
except IOError:
connectionSocket.send("file not found")
serverSocket.close()
sys.exit()
The error comes from the open statement. I dont fully understand how this line of code's return value is organized.
message = connectionSocket.recv(1024)
I know that the return value is in bytes but when I try to use a fuction to turn it into a string like decode() i get errors as well
I have the .py file and the html file sitting in the same directory on my local machine and the way I test this is I just run this and open up a browser and type in
http://127.0.0.1:4567/helloworld.html
My code then promptly crashes after receiving the HTTP request.
Any and all help will be greatly appreciated!
There are numerous problems with your code and since you don't state what specific issues you are concerned about, here is what I see:
connectionSocket.send(outputdata[i].encode())
connectionSocket.send("\r\n".encode())
That appears to send a newline after every character you send back to the client.
Also, it doesn't deal with the client disconnecting because you're sending back invalid data.
Even if what you were trying to do didn't have these errors in it, you don't appear to be attempting to send back a valid http response.
https://www.w3.org/Protocols/rfc2616/rfc2616-sec6.html
Related
I am trying to establish a client-server communication. The client is written in Ruby whereas the server is written in Python.
client.rb
require 'socket'
hostname = 'localhost'
port = 7778
s = TCPSocket.open(hostname, port)
s.write("2020-06-25T11:11:00+00:00 5 127.0.0.1 printer: event")
while line = s.gets
puts line.chop
end
s.close()
The ruby client sends a log to the Python server and tries to receive it back.
server.py
import socket
#Create a TCP/IP socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#bind the socket to the port - tuple
server_address = ('localhost', 7778)
print('starting up on %s port %s' %server_address)
sock.bind(server_address)
#Listen for incoming connections
sock.listen(1)
while True:
print('waiting for a connection')
connection, client_address = sock.accept()
while True:
data = connection.recv(1024)
print('received "%s"' % data)
if data:
print('sending data back to the client')
connection.send(data)
else:
print('no more data from', client_address)
break
connection.close()
The log is sent to the python server and when the python server sends it back. When the ruby client receives it, it doesn't receive the full log.
example:
2020-06-25T11:11:00+00:00 5 127.0.0.1 printer: eve
I think this comes from the fact that TCP is a streaming protocol and we never know if we can get the full message each time.
Could you propose me a solution for both the client and the server so I can be sure they always receive the full message between each other? I would really appreciate it if anyone would help.
So the issue is that you're assuming the data received has a new line character - however the data you're sending is not terminated by a new line.
s.write("2020-06-25T11:11:00+00:00 5 127.0.0.1 printer: event") will not write the string with a new line character - you should use puts IO#puts
s.gets will return the data because the socket is closed by the python server after it has sent the data. So even getssays it will read the next line from the socket, in reality its just reading what remained in the buffer after the socket was closed.
line.chop will remove the last character, and you're using it here to strip a newline character (assuming that it has one from gets). However since there is no newline character it will remove the last character instead.
So the fix would be to replace in the ruby client s.write with s.puts.
I've set up a python client and server with socket in Python, that allows the server to send text to the client and I've been trying to extend it so that images can be sent to the client.
Server code:
import socket
#setup and bind server socket
s_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)#setup socket
s_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)#reuses same port (allows reconnection)
s_socket.bind(('192.168.178.52', 9001))
s_socket.listen(1)
#connects and prints clients data and send message
clientsocket, address = s_socket.accept()
print('Connection from {}'.format(address))
clientsocket.send(bytes('Welcome to the server', 'utf-8'))
#Loops for server to sent text data to client
while True:
m = input('Enter')
try:
file = open(m, 'rb')
b = file.read(2048)
clientsocket.send(b)
except:
clientsocket.send(bytes(m, 'utf-8'))
Client code:
import socket
import webbrowser
import os
import pyautogui
#setup and bind client socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.connect(('----------', 9001))#ip swapped for post
while True:
message = s.recv(2048)#recieves all messages sent with buffer size
if message:
txt = str(message)
with open('plswork.png', 'wb') as file:
file.write(message)
file.close()
The problem I'm having is that it will send the file over and create it perfectly fine, but only part of the image will load in when i open it (see image) I am pretty sure this is something to do with the buffer size however when I increase it, it wont recognise the file at all and I'll get an error trying to open the photo (preferably you would be able to send most photos). New to python sockets so any help would be appreciated!
(at the moment trying to send a pic of tux...)
https://i.stack.imgur.com/lBblq.png
I don't know the size of the file, but shouldn't you read the file until it is read completely and send data in chunks?
while True:
m = input('Enter')
try:
file = open(m, 'rb')
while True:
b = file.read(2048)
if not b:
break
clientsocket.send(b)
except:
clientsocket.send(bytes(m, 'utf-8'))
Client side had to be adapted as well.
Most network protocols add more information to simplify reception.
It could for example be a good idea, if you first send the number of bytes, that the welcome message contains, then the welcome message, then some indicator, that you will send a file, then some information, how many bytes you will send for the image and only then the bytes of the image
You will also find out, that it is complicated for the client to know what is the text message and what is part of the png file.
In fact if you would remove the input() command from the server and hard code a file name you might probably notice. that the welcome message and the png file could arrive combined at the client side. and it would have difficulties separating the two.
So to make your code robust, there's a lot of work to do.
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())
We're learning about sockets in Networking and we've been tasked to fill out a template in Python (teacher's using Python2.x while I'm using Python3.x).
# Import socket module
from socket import *
# Create a TCP server socket
#(AF_INET is used for IPv4 protocols)
#(SOCK_STREAM is used for TCP)
serverSocket = socket(AF_INET, SOCK_STREAM)
# Assign a port number
serverPort = 6789
# Bind the socket to server address and server port
serverSocket.bind(('',serverPort))
# Listen to at most 1 connection at a time
serverSocket.listen(1)
# Server should be up and running and listening to the incoming connections
while True:
print ("Ready to serve...")
# Set up a new connection from the client
connectionSocket, addr = serverSocket.accept()
# If an exception occurs during the execution of try clause
# the rest of the clause is skipped
# If the exception type matches the word after except
# the except clause is executed
try:
# Receive the request message from the client
message = connectionSocket.recv(4096).decode()
# Extract the path of the requested object from the message
# The path is the second part of HTTP header, identified by [1]
filename = message.split()[1]
# Because the extracted path of the HTTP request includes
# a character '\', we read the path from the second character
f = open(filename[1:])
# Store the entire contenet of the requested file in a temporary buffer
outputdata = f.read()
# Send the HTTP response header line to the connection socket
connectionSocket.send(("HTTP/1.1 200 OK \r\n").encode())
# Send the content of the requested file to the connection socket
for i in range(0, len(outputdata.encode())):
connectionSocket.send(outputdata.encode())
connectionSocket.send(("\r\n").encode())
# Close the client connection socket
connectionSocket.close()
break
except IOError:
# Send HTTP response message for file not found
connectionSocket.send(("HTTP/1.1 404 NOT FOUND\r\n").encode())
connectionSocket.send(("<html><head></head><body><h1>ERROR. TRY AGAIN</h1></body></html>\r\n").encode())
# Close the client connection socket
connectionSocket.close()
break
#Close the Socket
serverSocket.close()
The file I'm reading into it is a .htm file:
<html><head><title>HTML Test File</title></head><body><h1>Trying to Get This Frickin' Program to Work</h1></body></html>
When I run the program and enter: localhost:6789/TestFile.htm, it prints the file contents over and over and gives me the error message: line 34, indexerror: list index out of range. edit: break takes care of the error message, but file is still being printed over and over
What am I doing wrong?
edit #2: now I'm trying to do the error handling, but it merely states that no data was sent when I type in a file that doesn't exist (i.e. localhost:6789/Test.htm). How do I get the error message to print?
for i in range(0, len(outputdata.encode())):
connectionSocket.send(outputdata.encode())
This code:
encodes the text twice
loops 121 times (which is the length of the file you posted, encoded as ASCII or UTF-8)
sends the entire file each of the 121 times
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.