HTTP Server Development with sockets - python

Objectives

🎯 Check final-server branch for final result - will be working towards it incrementally

• learn and practice the basics of socket programming for TCP connections in Python
  • how to create a socket,
  • bind it to a specific address and port, as well as
  • send and receive a HTTP packet
• get familiar with HTTP request/response format.

Provided Files

Test files are provided, and they should be put in the same directory that the server is in.

• TCPServer.py
  • this is a simple socket server in which the request message is any text line, and the response is the same text line but all letters are in upper case.
• TCPClient.py
  • a simple socket server in which the request message is any text line, and the response is the same text line but all letters are in upper case.
• index.html, flex.html - just to check that different routes are indeed working we will be using form.html later on. But
• form.html - as of now it's just to check (like flex.html)
  • other-git-branches : we will modify the server to handle POST requests
  • other-git-branches : return a templated-html(success.html) page populated from POST request response
  • other-git-branches : make the success.html be only accessible via form submission on form.html, visiting success.html directly will redirect to form.html with warning-text
• .gitignore : you don't need to worry about this file. It's a hidden file which has a lit of all the files we've asked git to not track. E.g.
  • after adding test*.py to .gitignore file
  • now anything which starts with test and ends with .py will not be tracked by git
  • To test this - make a file called test.py or testanything.py, as long as the name starts with test and ends with .py
  • Notice: how git will not include it as part of files to commit

Test if working

Running the Provided Server, open terminal and type :

• python3 file_name.py

  running TCPServer.py/TCPClient.py file will run server/client respectively

FOR BASIC SERVER Files provided in Repo

• run server and client both are running.
• Sending some text(e.g. test-text) from client-temnial should output TEST-TEXT on the client-terminal.
  Meanwhile the server-terminal should print Requested Text: test-text
  

FOR HTTP-WEB-SERVER

UPPERCASE-transformation shouldn't be working anymore.

Run the server file, but for client - your Web-Browser is the client
TCPClient.py file isn't needed anymore at this point.

Open a browser, and type in the request : http://localhost:8000/index.html

All the test files should be successfully retrieved from the server.

💡Pro-tip : don't forget to close the things you open ;)

Deliverables : Web Server : TCPServer.py

We assume no header lines are involved.

• that handles one HTTP request at a time
• should accept and parse the HTTP request,
  • get the requested file from the server’s file system,
  • create an HTTP response message which contains the requested file, and then
  • send the response directly to the client.
  • If the requested file is not present in the server, the server should send an HTTP “404 Not Found” message back to the client.
• if no file is specified - i.e. http://localhost:8000, then the server should return index.html
• If file is sent - a 200 response message should be sent back
• If file does not exist - a 404 response message should be sent back
• If any other error occurs - a 404 response message should be sent back

You may expand the TCPServer.py provided in the github repo to implement the Web server.

Later, not part of this TCPserver.py but in different branch.
TCPServer.py is expanded to,

• http post-request server

• inaccessible webpage (can only be seen after a form submission)

  • this is also a template webpage - which substitute {{fname}} with data from form submission

• gotta look into it

  • serve images, CSS & Js file as well (that would involve headers & MIME types)
  • multiple http connections
  • technically, adding hot-reloading capability is a possibility
    • similar to VS-Code Live server (Readme)
  • try making it accesible via internet (using ngrok)
  • hosting it on a live URL accesible from anywhere on the internet.

Additional Information

In the WebServer, the request message is an HTTP GET request line. In the form of

GET /filename HTTP/1.1

Please notice that this server only process GET, and does not care about the version, so that the only useful portion is the second portion: /filename

Obtain the filename. Any Python string process functions can be used, such as split().

After the filename is retrieved from the message, you may want to open this file. Thus, python file processing functions, such as open(), should be used.

Different mechanisms can be used to determine if a file can be opened. One way is to use try...except...finally structure.

Run the server program. This server and the client may be in different hosts. Here we assume the server and the client are in the same host. Please use port 8000 instead of port 80.

👀 HINT 👀
Printing the request you're getting from the client helps. In the TCPClient.py - you're the one sending some data to the TCPServer, but with web browser - think of it like, web browser already has some templated response ready (in the form of HTTP Get request).

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Credit :

2023F CS-3420-01-Assignment 2 HTTP Server Development

The theory covered in this project is by Jim Kurose (Youtube). I've changed it extensively and built on top of it. The original assignemt was just a simple http-get-server, but I messed around a bit, to see if I can make POST server and kept adding different capabilities.