Homework 3: Writing a Web server
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Due Thursday, Sep 18th, at 12:40pm (class start).

Section 0: Cleanup
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Deal with my comments on the second homework: fix problems, etc.

Section 1: Non-blocking TCP echo server
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Write a non-blocking version of the TCP echo server that can accept
and handle multiple connections **without using threads or multiple
processes**.  You should use ``sockobj.setblocking(0)`` to set your
sockets to non-blocking.

Please be sure separate the code that handles reading and writing into
a function ``handle_connection(sockobj)`` separate from the main body of
the code; that is, you should have a main block that deals with
accepting new connections and then calls the ``handle_connection``
function to do read/write.  ``handle_connection`` should take precisely
one argument and return ``True`` if the connection remains open and
``False`` otherwise.

Be sure to test that your program can handle 2 or more connections
simultaneously.  I would suggest writing a test client program, but
that's up to you.

The echo server should be submitted via the Subversion server and
be executable like so: ::

  python homework3/echo-server-nb <host> <port>

Section 2: Write a simple Web server
------------------------------------

Using only the socket networking library, write an HTTP server that returns
"hello, %s" to a GET URL request, where '%s' is replaced by the URL path being
requested.  For example, ::

  python homework3/webserve <port>

starts a Web server that answers on the given port and can be accessed at ::

  http://localhost:<port>/

If the Web server is accessed at

  http://localhost:<port>/some/random/url

then the returned page content is

  hello, /some/random/url

The returned code should be 200 and the returned content-type should
be ``text/html``.

This HTTP server should *ignore* any query strings; that is,
/some/random/url?BLAH will return the same thing as /some/random/URL.
The HTTP server should also ignore any non-GET requests; it's ok to
leave the behavior undefined for non-GET requests (i.e. don't bother
putting in error-handling for them unless you want to).

Your Web server should be implemented well enough that Firefox or
Safari can talk to it, but this doesn't mean you need to implement the
full HTTP/1.0 spec.