Tim Zulf- WIP: #212

Tulf · 2018-12-03T20:33:57Z

Days 1 and 2

1. Implement send_response().

This function is responsible for formatting all the pieces that make up an HTTP response into the proper format that clients expect. In other words, it needs to build a complete HTTP response with the given parameters. It should write the response to the string in the response variable.

The total length of the header and body should be stored in the response_length variable so that the send() call knows how many bytes to
send out over the wire.

See the HTTP section above for an example of an HTTP response and use that to build your own.

Hint: sprintf() for creating the HTTP response. strlen() for computing
content length. sprintf() also returns the total number of bytes in the
result string, which might be helpful. For getting the current time for the Date field of the response, you'll want to look at the time() and localtime() functions, both of which are already included in the time.h header file.

The HTTP Content-Length header only includes the length of the body, not
the header. But the response_length variable used by send() is the
total length of both header and body.

You can test whether you've gotten send_response working by calling the resp_404 function from somewhere inside the main function, and seeing if the client receives the 404 response.
2. Examine handle_http_request() in the file server.c.

You'll want to parse the first line of the HTTP request header to see if this is a GET or POST request, and to see what the path is. You'll use this information to decide which handler function to call.

The variable request in handle_http_request() holds the entire HTTP request once the recv() call returns.

Read the three components from the first line of the HTTP header. Hint: sscanf().

Right after that, call the appropriate handler based on the request type
(GET, POST) and the path (/d20 or other file path.) You can start by
just checking for /d20 and then add arbitrary files later.

Hint: strcmp() for matching the request method and path. Another hint:
strcmp() returns 0 if the strings are the same!

Note: you can't switch() on strings in C since it will compare the string pointer values instead of the string contents. You have to use an
if-else block with strcmp() to get the job done.

If you can't find an appropriate handler, call resp_404() instead to give
them a "404 Not Found" response.
3. Implement the get_d20() handler. This will call send_response().

See above at the beginning of the assignment for what get_d20() should pass to send_response().

If you need a hint as to what the send_response() call should look like, check out the usage of it in resp_404(), just above there.

Note that unlike the other responses that send back file contents, the d20 endpoint will simply compute a random number and send it back. It does not read the number from a file.

The fd variable that is passed widely around to all the functions holds a file descriptor. It's just a number use to represent an open
communications path. Usually they point to regular files on disk, but in
this case it points to an open socket network connection. All of the code to create and use fd has been written already, but we still need to pass it around to the points it is used.
4. Implement arbitrary file serving.

Any other URL should map to the serverroot directory and files that lie within. For example:

http://localhost:3490/index.html serves file ./serverroot/index.html.

http://localhost:3490/foo/bar/baz.html serves file
./serverroot/foo/bar/baz.html.

You might make use of the functionality in file.c to make this happen.

You also need to set the Content-Type header depending on what data is in
the file. mime.c has useful functionality for this.

Days 3 and 4

Implement an LRU cache. This will be used to cache files in RAM so you don't have to load them through the OS.

When a file is requested, the cache should be checked to see if it is there. If so, the file is served from the cache. If not, the file is loaded from disk, served, and saved to the cache.

The cache has a maximum number of entries. If it has more entries than the max, the least-recently used entries are discarded.

The cache consists of a doubly-linked
list and a
hash table.

The hashtable code is already written and can be found in hashtable.c.

1. Implement cache_put() in cache.c.

Algorithm:
- Allocate a new cache entry with the passed parameters.
- Insert the entry at the head of the doubly-linked list.
- Store the entry in the hashtable as well, indexed by the entry's path.
- Increment the current size of the cache.
- If the cache size is greater than the max size:
  - Remove the entry from the hashtable, using the entry's path and the hashtable_delete function.
  - Remove the cache entry at the tail of the linked list.
  - Free the cache entry.
  - Ensure the size counter for the number of entries in the cache is correct.
2. Implement cache_get() in cache.c.

Algorithm:
- Attempt to find the cache entry pointer by path in the hash table.
- If not found, return NULL.
- Move the cache entry to the head of the doubly-linked list.
- Return the cache entry pointer.
3. Add caching functionality to server.c.

When a file is requested, first check to see if the path to the file is in
the cache (use the file path as the key).

If it's there, serve it back.

If it's not there:
- Load the file from disk (see file.c)
- Store it in the cache
- Serve it

There's a set of unit tests included to ensure that your cache implementation is functioning correctly. From the src directory, run make tests in order to run the unit tests against your implementation.

coneptual mapping.

NandoTheessen

Left a comment on how you could finish up that send_response().

I know it can be hard sometimes, but please try and put in productive commit messages.
This is one of the things hiring partners are really looking into, so now would be a good time to pick up good habits!

NandoTheessen · 2018-12-04T01:19:18Z

src/server.c

@@ -59,7 +59,8 @@ int send_response(int fd, char *header, char *content_type, void *body, int cont
    // response_length = sizeof(respone)/sizeof(char)?
    // just initalize response length for now
    int response_length = 0;
-    int response_length = sprintf(
+
+    response_length = sprintf(
      response,
      "%s\n connection:\n content_length: %d\n content_type: %s\n\n%s", header, content_length, content_type, body


Almost there, Tim!

I'd go ahead and separate the arguments into strings, something like
response_length = sprintf( response, "%s\n" "connection: close\n" "content_length: %d\n" content_type: %s\n\n" "%s\n", header, content_length, content_type, body);

And you should be good to go!

-send response, -get_d20 -handle_http_request Server returns get request information but stops due to segemnetation fault.

… file for handle request, perhaps I need to set an explicit conditional for each file?

perhaps my get_file logic is just wrong.

for some reason it doesn't read the file in correctly.

…seems, but I'm still not sure why I need to direct to the endpoint in this way.

NandoTheessen

Good job, Tim!
Were you able to test this locally?
Does it work?

NandoTheessen · 2018-12-05T01:11:48Z

src/server.c

+                //    Check if it's /d20 and handle that special case
+                if(strcmp(file, "/d20") == 0) {
+                        get_d20(fd);
+                } else if(strcmp(file, "/index.html") == 0) {


Couldn't we just have the else statement from line 217 here, instead of making 2 additional if's ?

It didn't work until I did that so idk. I'll try to get it to work with a simple if else.

nevermind I got it to work without that stuff. I thought about what I was doing and realized that foobar file was just an example 😂

NandoTheessen · 2018-12-05T01:12:09Z

src/server.c

+        ///////////////////
+        // IMPLEMENT ME! //
+        ///////////////////
+        char file[4096];


Great job on implementing this! 👍

NandoTheessen · 2018-12-05T01:14:35Z

src/server.c


-    // Unreachable code
+        // Unreachable code


This isn't really unreachable code.
What's impossible here is sending out responses or getting at the request because the socket has been closed.
Statement would be true if below the return.

(Of course this is nit-picky. You did a good job today so not much to criticise 🥇 )

NandoTheessen · 2018-12-05T01:16:08Z

A lot better on the commit messages! There are quite a lot and they are meaningful, keep it up!

can now handle arbitrary files.

made body into char.

tests still don't pass.

copied over strings.

Not getting into LRU cache.

Tulf added 6 commits December 3, 2018 15:32

Tim Zulf- WIP:

56bab41

coneptual mapping.

implemented random number

38dafa8

random number

702a66e

send_response.

6d6acdf

sprintf lol

c102306

also lol

3478dd0

NandoTheessen reviewed Dec 4, 2018

View reviewed changes

Tulf added 7 commits December 4, 2018 18:17

implemented functions:

52331d0

-send response, -get_d20 -handle_http_request Server returns get request information but stops due to segemnetation fault.

arbiitrary file handlinge, not fully tested yet.

374dae1

chngaed to conditional print statement, it seems to not read from the…

3f0c3b3

… file for handle request, perhaps I need to set an explicit conditional for each file?

set conditional statements into handle_http request,

934b253

perhaps my get_file logic is just wrong.

renaming it all the same does not seem to work.

4aa91f2

for some reason it doesn't read the file in correctly.

okay there was a silly error, so it does load the file correctlly it …

2ca7524

…seems, but I'm still not sure why I need to direct to the endpoint in this way.

beautified code.

5b5b939

NandoTheessen reviewed Dec 5, 2018

View reviewed changes

Tulf added 11 commits December 4, 2018 22:55

handle_http_request if else simplified.

f48c0af

can now handle arbitrary files.

added date.

e66d525

made body into char.

cast body variable correctly. cacheput and cacheget

bbe7cf2

free and cache entry implemented.

a5854da

cache_create

5de24cb

fix

419261c

fixed put and get

aac283b

can't pass tests idk why

18875fe

Server can run, seem to be able to make requests normally now

2af36de

tests still don't pass.

commiting because whynot?

f6f3ba2

copied over strings.

changed cache.c to be able to serve files.

0413a58

Not getting into LRU cache.

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Tim Zulf- WIP: #212

Tim Zulf- WIP: #212

Tulf commented Dec 3, 2018 •

edited

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NandoTheessen Dec 4, 2018

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NandoTheessen Dec 5, 2018

Tulf Dec 5, 2018

Tulf Dec 5, 2018

NandoTheessen Dec 5, 2018

NandoTheessen Dec 5, 2018

NandoTheessen commented Dec 5, 2018

Tim Zulf- WIP: #212

Are you sure you want to change the base?

Tim Zulf- WIP: #212

Conversation

Tulf commented Dec 3, 2018 • edited

Days 1 and 2

Days 3 and 4

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NandoTheessen commented Dec 5, 2018

Tulf commented Dec 3, 2018 •

edited