Take data from socket connection and split it

Question

This is from a homework question but I'm not too familiar with Python and couldn't find any information on what is going on in the statements below.

 message = connectionSocket.recvfrom(1024)
 filename = message.split()[1] 
 f = open(filename[1:]) 

So, message is just taking the data from the client connected to connectionSocket and putting it in message. From there I can tell that the message is split which means its taking the string in message and returning a list of words (which I'm guessing the delimiter is just a space). But what is that [1]?

It's supposed to be a webserver so I'm thinking of a scenario such as if I go to serverAddress:serverPort/HelloWorld.html the message is the 'HelloWorld.html" part, right? and then I am opening the file. But I'm lost on the purpose of [1] and [1:].

Answer 1

filename = message.split()[1]

You guessed (correctly) that the string in message is split and returned as a list of words.

If this is a HTTP request, then the first 1024 bytes of message will be something like:

"GET /file.html cruft..." or "GET /path/file.html cruft..." .

By split ting this string you generate a list beginning:

["GET", "/file.html", "cruft..."] .

The [1] denotes the element indexed [1] within the list, ie the second element, the first index position being [0]. So filename = "/file.html" or = "/directory/subdirectory/file.html"

---

f = open(filename[1:]) 

This slices whatever is in filename , again using the indices. [1:] returns every element of filename from [1] to the end. If the assumptions above are right, then it'll discard the leading / and allow the file to be opened.