General

codecrafters build your own HTTP server in C

HTTP is the protocol that powers the web. In this challenge, you'll build a HTTP server that's capable of handling simple GET/POST requests, serving files and handling multiple concurrent connections.

Along the way, we'll learn about TCP connections, HTTP headers, HTTP verbs, handling multiple connections and more.

Tasks

Binding to Port

$ ./your_program.sh

Respond with 200

In HTTP response is made up of three parts, each separated by a CRLF (\r\n):

Status line.
Zero or more headers, each ending with a CRLF.
Optional response body.

In this stage, your server's response will only contain a status line. Here's the response your server must send: HTTP/1.1 200 OK\r\n\r\n

To test simply run $ ./your_program.sh and $ curl -v http://localhost:4221

Extract URL path

An HTTP request is made up of three parts, each separated by a CRLF (\r\n):

Request line.
Zero or more headers, each ending with a CRLF.
Optional request body.

Here's an example of an HTTP request: GET /index.html HTTP/1.1\r\nHost: localhost:4221\r\nUser-Agent: curl/7.64.1\r\nAccept: */*\r\n\r\n The "request target" specifies the URL path for this request. In this example, the URL path is /index.html

To test simply run $ ./your_program.sh and $ curl -v http://localhost:4221/abcd

Your server must respond to this request with a 404 response

Respond with body

In this stage, you'll implement the /echo/{str} endpoint, which accepts a string and returns it in the response body. Your /echo/{str} endpoint must return a 200 response, with the response body set to given string, and with a Content-Type and Content-Length header.

To test simply run $ ./your_program.sh and $ curl -v http://localhost:4221/echo/abcd

this will return abcd

Read Header

In this stage, you'll implement the /user-agent endpoint, which reads the User-Agent request header and returns it in the response body. The User-Agent header describes the client's user agent.

Here is an example:

// Status line
HTTP/1.1 200 OK               // Status code must be 200
\r\n

// Headers
Content-Type: text/plain\r\n
Content-Length: 12\r\n
\r\n

// Response body
foobar/1.2.3                  // The value of `User-Agent`

To test simply run $ ./your_program.sh and $ curl -v --header "User-Agent: foobar/1.2.3" http://localhost:4221/user-agent

Concurrent Connections

In this stage, you'll add support for concurrent connections. To test simply run $ ./your_program.sh and

$ (sleep 3 && printf "GET / HTTP/1.1\r\n\r\n") | nc localhost 4221 &
$ (sleep 3 && printf "GET / HTTP/1.1\r\n\r\n") | nc localhost 4221 &
$ (sleep 3 && printf "GET / HTTP/1.1\r\n\r\n") | nc localhost 4221 &

Return a file

In this stage, you'll implement the /files/{filename} endpoint, which returns a requested file to the client. The tester will execute your program with a --directory flag. The --directory flag specifies the directory where the files are stored, as an absolute path.

$ ./your_program.sh --directory /tmp/

The tester will then send two GET requests to the /files/{filename} endpoint on your server.

Read Request body

In this stage, you'll add support for the POST method of the /files/{filename} endpoint, which accepts text from the client and creates a new file with that text.