[RESOLVED] Comparing input to a password in a flatfile

PanamaKid

Hello,
I'm trying to set up a little puzzle where if someone solves the puzzle a password is displayed in an image. They must then type that password into a text input box to move on to the next page. On page challenge1.php I have the following code:

<form name="nextchallenge" method="post" action="challenge2.php">
Password for next Challenge: <input type="text" name="password">
<input type="submit" value="Submit!" name="submitted">
</form>

On page challenge2.php I have the following code before the <html> tag:

<?php

function CheckLogin($pw)

{

$valid=false;
$f = fopen("password1.txt","r");
$line = fgets($f);
if ($line = $pw)
	$valid=true;
}
if($valid=true)

return=true;
else
	return=false;
?>
<?php
if(!CheckLogin($_POST=['password']))

	echo "Error";
else
	header('Location: challenge2.php');

?>

I'm getting an unexpected '=' on line 10 type of error. Any help would be appreciated!

Derokorian

= is an assignment operator it would be return TRUE; however this return isn't inside of your function so you are just doing it, especially since your if($valid=true) is also wrong, as it is also using an assignment operator (instead of comparison) also you have no brace and the next line is empty, which means your if does nothing, not to mention the else will have no matching if.

bradgrafelman

Derokorian;10990896 wrote:
your if($valid=true) is also wrong, as it is also using an assignment operator (instead of comparison) also you have no brace and the next line is empty, which means your if does nothing, not to mention the else will have no matching if.

Not true - the if/else will work just fine. PHP cares about the next statement, not the next line. You could a 100-line script and (most likely) combine it down to a single line of code, or you could spread it out over 1000 lines; for the most part, PHP ignores whitespace in the code.

PanamaKid

Derokorian;10990896 wrote:
= is an assignment operator it would be return TRUE; however this return isn't inside of your function so you are just doing it, especially since your if($valid=true) is also wrong, as it is also using an assignment operator (instead of comparison) also you have no brace and the next line is empty, which means your if does nothing, not to mention the else will have no matching if.

Thank you for the suggestion Derokorian, but I'm pretty sure I don't need a brace or to fill in the empty lines.... this problem is just so troublesome and I have no idea what it could be... Seems like it should be simple to do this...

bradgrafelman

PanamaKid;10990902 wrote:
Thank you for the suggestion Derokorian, but I'm pretty sure I don't need a brace or to fill in the empty lines.... this problem is just so troublesome and I have no idea what it could be... Seems like it should be simple to do this...

While the missing braces are indeed optional, the other points Derkorian made are definitely not. Here's a list of problems (or possible problems) I see:

```
$f = fopen("password1.txt","r"); 
    $line = fgets($f); 
```
If the file contains even a single line break after the password, it will be included in the return value... meaning a user would have to somehow include the line break (and guess which line break to use - did you know there are three different choices?) in their input.

If this is the case, you might consider using [man]trim/man.
```
    if ($line = $pw) 
        $valid=true; 
```
Inside the if() conditional, you are assigning the value of $pw to the variable $line and evaluating that value as a boolean (meaning anything that can't be loosely typed to boolean false is considered true - regardless of whether it actually matched the password in the text file).

As Derokorian pointed out, the single '=' operator is the assignment operator. Perhaps you meant to compare things instead? (See: [man]operators.comparison[/man])
```
if($valid=true) 

return=true; 
else 
    return=false; 
```
This section has numerous problems. And they are:
1. Again, you're assigning the value of true to the variable $valid.
2. Speaking of that variable, did you know you're actually creating it here, since it isn't defined previously? Note that variables inside of a function's scope stay there - once you're outside of the function, they no longer exist.
3. The [man]return[/man] statement doesn't have an equal sign anywhere in it... at least, not if you expect your code to parse correctly it won't.
4. Even if you got rid of the equal signs, the [man]return[/man]'s would be invalid here since you aren't inside any function. (Hint: Your current function doesn't return anything, meaning it's pretty much useless as-is since it never exposes the result of the attempted comparison.)
```
if(!CheckLogin($_POST=['password'])) 
```
Why is there an equal sign between an array and the index you're attempting to select from it? See the manual page for what an [man]array[/man] is and how to access items at a given index.

Oh, and by the way - when posting PHP code, please use the board's [noparse]

..

[/noparse] bbcode tags as they make your code much easier to read and analyze.

PanamaKid

Thank you both for your help so far! I know it takes a lot more effort to explain and have someone find out the details than it does to just write the code. I understood what you guys have mentioned and have this now

<?php
function CheckLogin($pw)

{

$valid=false;

$f = fopen("password1.txt","r");
$line = fgets($f);
if (line == $pw)
	$valid=true;


if(valid==true)

return true;

else

return false;
}
?>
<?php
if(CheckLogin($_POST['password']))

header('Location: /challenge2.php');

else
	echo "error";

?>

And now I'm getting an unexpected t_string error on the very first line (<?php>...) any further guidance you can provide?

bradgrafelman

I don't see any such error on the first line.. are you sure that code snippet is a direct copy-and-paste from your source code?

The two errors I do see, however, are missing $ signs in front of the variables in the two if() statements inside the function.

Also note that [man]header/man must be called before any output, yet you've got output between the function definition and the last if() statement containing the header() call. Note that any whitespace outside of <?php ... ?> tags is treated the same as any other data outside the tags - as output.

PanamaKid

Brad,
Thanks a bunch for your attention to detail, patience, and time! It's really appreciated and finally managed to get the issue resolved!