Permanent Programming 2

[sesteves86]

It was tought to make it under the 15 sec and to discover the 1st character problem, but it tastes good when we solve it
1st I was trying to decode the image with smallbasic, then the output I would copy-paste throught notepad to excel and get the remaining decoding there, but would take 15-20 sec to do the job.
I see that the goal is to make all the work with only 1 program.

[zyewni]

Weirdest thing - decided I'd have a go at this mission this morning.
Had to learn to work with images in PHP - interesting and fun. So script connects, logs in, hits the challenge page, goes and gets the image.
Spent a good hour working out the next bit (cut me some slack, had the baby to care for too).

Once I had everything worked out, and had verified that my responses were making sense over and over, I added in the lines to put the solution in the post data and send it. First try, I got an error, but not the one I was expecting - "YOU HAVE ALREADY COMPLETED THIS MISSION".

This script couldn't have sent the answer during my tests, because I never added it to the post data. And it's impossible that I would have completed it before - I just learned the necessary skills this morning. Odd.

And I never did figure out how to display the image in my browser after

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$source = connect($sess,"missions/prog/2/PNG/",$postdata);
$image = imagecreatefromstring($source);

I tried all sorts of function calls, just kept displaying symbol soup. Everything parses fine, I just would have liked to output the image as well as debugging strings.

[wan26]

I did this in c++ by saving the .png [set the download path to my codeblocks project directory] and pasted the answer from my terminal, for a bit I was wondering why my answer was wrong. This is the place in my function that creates morse tripped up;

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for (int x = 1; x<=49; x++) { // I set the max value of x to 39 because i was testing a particular image for a while, finally changed it 49 to accept more values ha

    outfile << char(array[x] - array[y]);
        y++;
    }


Glad it's over! But at least I have some nifty things to re use later. I recommend the cimg library if you're going to write it all in c++, it worked wonders.

[That_One_Hacker]

I used c++ as well and I would also recommend the CImg library. It's quick and easy to learn (if you already know c++). These are definately some great challenges to help yourself become a better programmer. So if you are thinking about cheating, I would suggest writing the code yourself, instead of just blowing through all of the chellenges, so you can learn something new. I've only done 2 of the programming challenges so far but I have been challenged more with this program than any of the programming courses I have taken at my college (as of now). Then again, I have never thought about doing anything like parsing through pixels of an image but that just means this was a good mission.

[Pure_Cadence]

I solved it in Java. Make sure to add the first byte into the array. I skipped over the first one (lets say 46) and that messed me up.

[oasis]

I'm having trouble doing this in Java. I'm trying to use the getRbg(x,y) method but I'm not sure how to check if the pixel is white. I tried

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if(red == 255 && green == 255 && blue == 255)

with no luck.

-- Tue Nov 08, 2016 9:46 am --

I'm having trouble doing this in Java. I'm trying to use the getRbg(x,y) method but I'm not sure how to check if the pixel is white. I tried

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if(red == 255 && green == 255 && blue == 255)

with no luck.

I've figured it out. Now I need to try and convert the morse code to text. Is it all in capital letters? Also do the pixels in the picture change every time we load the page?

EDIT: I have completed the mission. I had to slightly cheat. I knew my first letter wasn't right so I added "-" to my first array and it worked! You need a black belt in copy and paste. It would be good to do this without copy and paste but no idea how that would be done with Java.

[Diggersby]

I am attempting to solve this problem in J, but I am having difficulty requesting the image from the website. I successfully make a socket connection to the website:

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NB. Define verb (function) socketinit
socketinit =: 3 : 0
NB. Create socket named sk
sk =: 0 >@{ sdcheck sdsocket''
NB. Retrieve IP of y (or for non-J programmers, the parameter to the right of socketinit)
IP=. sdcheck sdgethostbyname (y)
NB. define port
prt=. 80
NB. make socket connection
sdconnect sk;IP,(<prt)
NB.defining the HTTP GET request
getreq =: (; format httpReq)
req sdsend sk,0
getres =: sdcheck sdrecv sk,100000,0
)

NB. formats the httpReq I have defined below to be of the
NB. proper format.
format =: (CR,LF)&(,~)&.>@:<;._2

NB. HTTP Request to retrieve image.
httpReq =: 0 : 0
GET /missions/prog/2/PNG.png/ HTTP/1.1
Host: www.hackthissite.org
Connection: keep-alive
)

I know not all of you are familiar with this language, so I would like to make it clear that my question is more to do with my GET request being formatted properly. Or if I'm overlooking some important prerequisite to requesting the image.
I should be clear that after the use of the "format" function on the httpreq, the variable "getreq" goes,
'GET /missions/prog/2/PNG.png/ HTTP/1.1',CR,LF,'Host: www.hackthissite.org',CR,LF,'Connection: keep-alive',CR,LF,CR,LF

Thanks for reading!

[boriz666]

Greetings Sir,
I am not familiar with J myself, but I believe you have not logged in to the
site, that is needed in order to get the image. In http terms you need to set
the cookie you get when providing the correct credentials.

In my case i program in perl and i have made a function in order to log into
hts programmatically. The $ua object is a global variable that holds state
like cookies and other useragent settings.

I am not familiar with J, what mechanisms you have available for storing the
cookies the website sends you, but when you login you have to save the
Set-Cookie header field and resend it as a Cookie header field in subsequent
requests.

I hope this clears it up and will get you on the path.

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sub siteLogin {
  my $login = shift;
  my $pass = shift;

  my $req = HTTP::Request->new(POST => "https://www.hackthissite.org/user/login");
  $req->header('Host', 'www.hackthissite.org');
  $req->header('Referer', 'https://www.hackthissite.org/');
  $req->content_type('application/x-www-form-urlencoded');
  $req->content("username=" . $login . "&password=" . $pass . "&btn_submit=Login");

  my $res = $ua->request($req);
  return 1;
}


[Diggersby]

Greetings Sir,
I am not familiar with J myself, but I believe you have not logged in to the
site, that is needed in order to get the image. In http terms you need to set
the cookie you get when providing the correct credentials.

In my case i program in perl and i have made a function in order to log into
hts programmatically. The $ua object is a global variable that holds state
like cookies and other useragent settings.

I am not familiar with J, what mechanisms you have available for storing the
cookies the website sends you, but when you login you have to save the
Set-Cookie header field and resend it as a Cookie header field in subsequent
requests.

I hope this clears it up and will get you on the path.

Thank you very much. I had also tried logging in with a post request but I had kept neglecting to copy down the cookie. I feel silly now. Your assistance is greatly appreciated.

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