amar-chaudhari / python-webserver

Python WebServer using TCP sockets

TLEN 5330 Programming Assignment 2

Objectives

• To create a HTTP-based web server that handles multiple simultaneous requests from users.

Background

• In this Assignment we are expected to learn basic of TCP socket Programming.
• We are expected to learn the HTTP protocol including various HTTP errors.
• We are also expected to learn socket threading and handle simultaneous requests using threading.

Requirments

• Python 2.7
• Document Directory: www
• Configuration file: ws.conf

Implementation Details

Read configuration parameters

• The server first reads configuration parameters from ws.conf file.
• The file contains derivateives such as server ip, port number and content-types
• If there is an error in the file then the server will start while returning HTTP 500 Internal server for all requests

Handling simultaneous requets

• Server handles simultaneous requests using multi-threading.
• The main server function create a new thread with handler function.
• The handler function then receives data from client, checks the request and then returns httpresponse
• If the handler function receives an Connection: Keep-Alive directive, it will set socket timeout and wait for more data.
• If no data was received in the timeout period or the last packet did not have a Connection: Keep-Alive derivateiv then the handler function will close the socket and kill the thread.

Error Handing

HTTP 400 Bad Request

• Server will first check for the method directive
  • if the method is not (GET,OPTIONS,HEAD,POST,PUT,DELETE,TRACE) it will return Invalid method error
• Server will next check the path of request file
  • if the path does not start with /, server will return Invalid URL error
• Server will next check for the HTTP version
  • if the verion is not HTTP/1.1 or HTTP/1.0, server will return Invalid HTTP-Verion error

HTTP 404 Not Found

• If the server can not find the requested file in DocumentRoot directory, it will return a 404 not found error

HTTP 501 Not Implemented

• If the method in request header is not present in RequestMethodSupport paramter of configuration file then server will return 501 not implemented error

HTTP 500 Internal Server Error

• If there is an error in server configuration file, such as no value specified for content-type or no port specified then server will return a 500 internal server error

How to run the program

Server

python2.7 webServer.py

Error Testing

404 Bad Requests

(echo -en "GET /index.html HTTP/2.1\r\nHost: localhost\r\n\n"; sleep 10) | telnet 127.0.0.1 8080
(echo -en "GRT /index.html HTTP/1.1\r\nHost: localhost\r\n\n"; sleep 10) | telnet 127.0.0.1 8080
(echo -en "GET /index.html HTTP/1.1\r\nHost: localhost\r\n\n"; sleep 10) | telnet 127.0.0.1 8080

501 Not Implemented

(echo -en "POST /index.html HTTP/1.1\r\nHost: localhost\r\n\n"; sleep 10) | telnet 127.0.0.1 8080