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Operating Systems
Homework Assignment #5
Due 15.1.2014, 23:59
Part 1
In this section you will write an HTTP server.
The HTTP server listens for connections, with worker threads constantly running in the background. Whenever a
client connects, its socket is enqueued to a shared queue, to be handled by one of the worker threads.
Write a program http_server.o. It will receive three arguments: number of threads, max requests, and port
number. Port number is an optional argument, use default HTTP port if not provided.
Implement a shared Queue data structure:
ο· Implemented by a linked-list (singly-linked) with a global lock, and head and tail pointers.
ο· The maximal size of the queue is determined by the πππ₯ ππππ’ππ π‘π argument. On an enqueue operation
that exceeds this size, return an error code (-1) to the calling thread.
ο· You may assume max ππππ’ππ π‘π β₯ 0, where an argument of 0 is valid and can be used for testing.
ο· To enqueue or dequeue, grab the lock and perform the required operation.
o Grab and release the lock in appropriate places! Do not hold the lock for performing operations
where the lock isnβt needed (allocating a queue item before enqueue, etc.).
ο· Use condition variables where appropriate.
In the main thread:
ο· Create the required number of worker threads.
ο· Create a socket and listen for incoming connections.
o When a connection is made, enqueue the new socket into the shared queue.
o If the queue is full, return Service Unavailable (HTTP 503) to the client and close the connection.
In each worker thread, repeatedly:
ο· Dequeue a socket item from the queue.
ο· Read the clientβs HTTP request and parse it.
o Only GET/POST operations β return Not Implemented (HTTP 501) for any other operation.
o Do not parse any info except the request line. Ignore request headers, cookies, etc.
ο· Return a minimal HTTP response to the client according to the request
o Find the requested file on your machine (treat it as a path).
o If it is not found, return Not Found (HTTP 404) response (including simple body).
o If it is a directory, create a simple HTTP body listing the directoryβs contents.
o If it is a file, return an HTTP response with the fileβs contents as the body.
ο· Close the socket.
Pressing CTRL+C (SIGINT) should exit the server properly!
i.e., use a signal handler to stop any running threads, close sockets, etc., before terminating.
You can & should wait for threads to finish handling any current clients before terminating (i.e., empty the queue).
Your browser should work with your server (navigate to URL βπ‘π‘π://πππππβππ π‘: < ππππ‘ >/< ππππ >).
