$queryDetails = mysql_query("SELECT * from members WHERE username = '$current_url' ");
I'm trying to use fwrite to create a page on register. This is the only thing what is going wrong. As I'm using 'fwrite', I cannot use speech marks as it ends the 'fwrite' command.
I've tried escaping the query out;
$queryDetails = mysql_query('SELECT * from members WHERE username = \'$current_url\' ');
But that hasn't worked. I can't use " as it closes the fwrite.
Any help?
The full code is
$queryDetails = mysql_query('SELECT * from members WHERE username = \'$current_url\' ');
$queryNumRowsDetails = #mysql_num_rows($queryDetails);
if ($queryNumRowsDetails != 0){
//collect data from SQL database
while ($row = mysql_fetch_assoc($queryDetails)){
$dbUsername = $row['username'];
$dbClub = $row['club'];
$dbReputation = $row['reputation'];
}
}
else{
die("There was a problem gathering user data.");
}
And if I try to escape the ' as shown in the second code block. It goes to the "There was a problem gathering user data."
$current_url is a variable collecting the current URL and taking away a few bits, leaving only a username remaining. Meaning example.com/users/AdziHades/index.php equates to just AdziHades.
Though your question lacks the information indicating what's not working, it looks like your problem with the query might be that you're using single quotes and trying to have it evaluate the variable inside. For example:
$myvar = 2;
$mystring = "I have $myvar apples.";
In that code, $mystring would evaluate to I have 2 apples.. If, instead, you use single quotes, like so:
$myvar = 2;
$mystring = 'I have $myvar apples.';
You will get I have $myvar apples.'. This is because single quotes will not evaluate variables automatically. Note: I am NOT referring to the quotes used in the query itself (around $current_url), I'm talking about the quotes around the entire query.
You have two options here. The 'easy' option is to just concatenate the value of the variable. The better, more future-proof way is to switch to using prepared statements with PDO (here is a page that explains why you should be using this and how to use it or at least mysqli. Prepared statements will allow for more secure queries without you having to manually escape your values to prevent SQL injection. I highly recommend you look at going down this route. The mysql_* extensions you're using have been deprecated and will most likely cause you problems in the future.
I've made a simple search-script in PHP that searches a mySQL database and outputs the result. How this works is like this:
User searches for "jack's" through a search-form.
My PHP-script GETs this search, and sanitizes it.
Then the script, with the use of SELECT and LIKE, gets the results.
The script then outputs the result to the user.
Lastly, the script tells the user that "jack's returned x results." with the help of escaping.
What I would like to ask is, am I doing it right?
This is how I sanitize before SELECTING from the database:
if(isset($_GET['q'])){
if(strlen(trim($_GET['q'])) >= 2){
$q = trim(mysql_real_escape_string(addcslashes($_GET['q'], '%_')));
$sql = "SELECT name, age, address FROM book WHERE name LIKE '%".$q."%'";
}
}
And this is how I escape before outputting "jack's returned x results.":
echo htmlspecialchars(stripslashes($q)) . " returned x results.";
Is this the correct way to do it?
By the way, I know that PDO and mySQLi is preferred as they sanitize themselves through the use of prepared statements, but I have no real experience with them whatsoever. But I would gladly take a look, if you guys could link me some newbie tutorials/explanations.
Furthermore, I heard that magic_quotes and charset could in some way or another lead to injections -- is this correct?
For some reason we need also escape a backslash too.
So, the proper code would be, I believe
if(isset($_GET['q'])){
$_GET['q'] = trim($_GET['q']);
if(strlen($_GET['q']) >= 2){
$q = $_GET['q'];
$q = '%'.addCslashes($q, '\%_').'%';
// now we have the value ready either for escaping or binding
$q = mysql_real_escape_string($q);
$sql = "SELECT name, age, address FROM book WHERE name LIKE '$q'";
//or
$sql = "SELECT name, age, address FROM book WHERE name LIKE ?";
$stm = $pdo->prepare($sql);
$stm->execute(array($q));
$data = $stm->fetchAll();
}
}
For the output, use
echo htmlspecialchars($_GET['q']);
stripslashes not needed here.
Furthermore, I heard that magic_quotes and charset could in some way or another lead to injections -- is this correct?
magic quotes won't harm your security if you won't use them.
charset is dangerous in case of some extremely rare encodings but only if improperly set. if mysql(i)_set_charset or DSN (in case of PDO) were used for the purpose - you are safe again.
As for PDO, a tag wiki should be enough for starter, I believe
Where and when do you use the quote method in PDO? I'm asking this in the light of the fact that in PDO, all quoting is done by the PDO object therefore no user input should be escaped/quoted etc. This makes one wonder why worry about a quote method if it's not gonna get used in a prepared statement anyway?
When using Prepared Statements with PDO::prepare() and PDOStatement::execute(), you don't have any quoting to do : this will be done automatically.
But, sometimes, you will not (or cannot) use prepared statements, and will have to write full SQL queries and execute them with PDO::exec() ; in those cases, you will have to make sure strings are quoted properly -- this is when the PDO::quote() method is useful.
While this may not be the only use-case it's the only one I've needed quote for. You can only pass values using PDO_Stmt::execute, so for example this query wouldn't work:
SELECT * FROM tbl WHERE :field = :value
quote comes in so that you can do this:
// Example: filter by a specific column
$columns = array("name", "location");
$column = isset($columns[$_GET["col"]]) ? $columns[$_GET["col"]] : $defaultCol;
$stmt = $pdo->prepare("SELECT * FROM tbl WHERE " . $pdo->quote($column) . " = :value");
$stmt->execute(array(":value" => $value));
$stmt = $pdo->prepare("SELECT * FROM tbl ORDER BY " . $pdo->quote($column) . " ASC");
and still expect $column to be filtered safely in the query.
The PDO system does not have (as far as I can find) any mechanism to bind an array variable in PHP into a set in SQL. That's a limitation of SQL prepared statements as well... thus you are left with the task of stitching together your own function for this purpose. For example, you have this:
$a = array(123, 'xyz', 789);
You want to end up with this:
$sql = "SELECT * FROM mytable WHERE item IN (123, 'xyz', 789)";
Using PDO::prepare() does not work because there's no method to bind the array variable $a into the set. You end up needing a loop where you individually quote each item in the array, then glue them together. In which case PDO::quote() is probably better than nothing, at least you get the character set details right.
Would be excellent if PDO supported a cleaner way to handle this. Don't forget, the empty set in SQL is a disgusting special case... which means any function you build for this purpose becomes more complex than you want it to be. Something like PDO::PARAM_SET as an option on the binding, with the individual driver deciding how to handle the empty set. Of course, that's no longer compatible with SQL prepared statements.
Happy if someone knows a way to avoid this difficulty.
A bit late anwser, but one situation where its useful is if you get a load of data out of your table which you're going to put back in later.
for example, i have a function which gets a load of text out of a table and writes it to a file. that text might later be inserted into another table. the quote() method makes all the quotes safe.
it's real easy:
$safeTextToFile = $DBH->quote($textFromDataBase);
I've always done the simple connection of mysql_connect, mysql_pconnect:
$db = mysql_pconnect('*host*', '*user*', '*pass*');
if (!$db) {
echo("<strong>Error:</strong> Could not connect to the database!");
exit;
}
mysql_select_db('*database*');
While using this I've always used the simple method to escape any data before making a query, whether that be INSERT, SELECT, UPDATE or DELETE by using mysql_real_escape_string
$name = $_POST['name'];
$name = mysql_real_escape_string($name);
$sql = mysql_query("SELECT * FROM `users` WHERE (`name` = '$name')") or die(mysql_error());
Now I understand this is safe, to an extent!
It escapes dangerous characters; however, it is still vulnerable to other attacks which can contain safe characters but may be harmful to either displaying data or in some cases, modifying or deleting data maliciously.
So, I searched a little bit and found out about PDO, MySQLi and prepared statements. Yes, I may be late to the game but I've read many, many tutorials (tizag, W3C, blogs, Google searches) out there and not a single one has mentioned these. It seems very strange as to why, as just escaping user input really isn't secure and not good practice to say the least. Yes, I'm aware you could use Regex to tackle it, but still, I'm pretty sure that's not enough?
It is to my understanding that using PDO/prepared statements is a much safer way to store and retrieve data from a database when the variables are given by user input. The only trouble is, the switch over (especially after being very stuck in my ways/habits of previous coding) is a little difficult.
Right now I understand that to connect to my database using PDO I would use
$hostname = '*host*';
$username = '*user*';
$password = '*pass*';
$database = '*database*'
$dbh = new PDO("mysql:host=$hostname;dbname=$database", $username, $password);
if ($dbh) {
echo 'Connected to database';
} else {
echo 'Could not connect to database';
}
Now, function names are different so no longer will my mysql_query, mysql_fetch_array, mysql_num_rows etc work. So I'm having to read/remember a load of new ones, but this is where I'm getting confused.
If I wanted to insert data from say a sign up/registration form, how would I go about doing this, but mainly how would I go about it securely? I assume this is where prepared statements come in, but by using them does this eliminate the need to use something like mysql_real_escape_string? I know that mysql_real_escape_string requires you to be connected to a database via mysql_connect/mysql_pconnect so now we aren't using either won't this function just produce an error?
I've seen different ways to approach the PDO method too, for example, I've seen :variable and ? as what I think are known as place holders (sorry if that is wrong).
But I think this is roughly the idea of what should be done to fetch a user from a database
$user_id = $_GET['id']; // For example from a URL query string
$stmt = $dbh->prepare("SELECT * FROM `users` WHERE `id` = :user_id");
$stmt->bindParam(':user_id', $user_id, PDO::PARAM_INT);
But then I'm stuck on a couple things, if the variable wasn't a number and was a string of text, you have to given a length after PDO:PARAM_STR if I'm not mistaken. But how can you give a set length if you're not sure on the value given from user in-putted data, it can vary each time? Either way, as far as I know to display the data you then do
$stmt->execute();
$result = $stmt->fetchAll();
// Either
foreach($result as $row) {
echo $row['user_id'].'<br />';
echo $row['user_name'].'<br />';
echo $row['user_email'];
}
// Or
foreach($result as $row) {
$user_id = $row['user_id'];
$user_name = $row['user_name'];
$user_email = $row['user_email'];
}
echo("".$user_id."<br />".$user_name."<br />".$user_email."");
Now, is this all safe?
If I am right, would inserting data be the same for example:
$username = $_POST['username'];
$email = $_POST['email'];
$stmt = $dbh->prepare("INSERT INTO `users` (username, email)
VALUES (:username, :email)");
$stmt->bindParam(':username, $username, PDO::PARAM_STR, ?_LENGTH_?);
$stmt->bindParam(':email, $email, PDO::PARAM_STR, ?_LENGTH_?);
$stmt->execute();
Would that work, and is that safe too? If it is right what value would I put in for the ?_LENGTH_?? Have I got this all completely wrong?
UPDATE
The replies I've had so far have been extremely helpful, can't thank you guys enough! Everyone has got a +1 for opening my eyes up to something a little different. It's difficult to choose the top answer, but I think Col. Shrapnel deserves it as everything is pretty much covered, even going into other arrays with custom libraries which I wasn't aware of!
But thanks to all of you:)
Thanks for the interesting question. Here you go:
It escapes dangerous characters,
Your concept is utterly wrong.
In fact "dangerous characters" is a myth, there are none.
And mysql_real_escape_string escaping but merely a string delimiters. From this definition you can conclude it's limitations - it works only for strings.
however, it is still vulnerable to other attacks which can contain safe characters but may be harmful to either displaying data or in some cases, modifying or deleting data maliciously.
You're mixing here everything.
Speaking of database,
for the strings it is NOT vulnerable. As long as your strings being quoted and escaped, they cannot "modify or delete data maliciously".*
for the other data typedata - yes, it's useless. But not because it is somewhat "unsafe" but just because of improper use.
As for the displaying data, I suppose it is offtopic in the PDO related question, as PDO has nothing to do with displaying data either.
escaping user input
^^^ Another delusion to be noted!
a user input has absolutely nothing to do with escaping. As you can learn from the former definition, you have to escape strings, not whatever "user input". So, again:
you have escape strings, no matter of their source
it is useless to escape other types of data, no matter of the source.
Got the point?
Now, I hope you understand the limitations of escaping as well as the "dangerous characters" misconception.
It is to my understanding that using PDO/prepared statements is a much safer
Not really.
In fact, there are four different query parts which we can add to it dynamically:
a string
a number
an identifier
a syntax keyword.
so, you can see that escaping covers only one issue. (but of course, if you treat numbers as strings (putting them in quotes), when applicable, you can make them safe as well)
while prepared statements cover - ugh - whole 2 isues! A big deal ;-)
For the other 2 issues see my earlier answer, In PHP when submitting strings to the database should I take care of illegal characters using htmlspecialchars() or use a regular expression?
Now, function names are different so no longer will my mysql_query, mysql_fetch_array, mysql_num_rows etc work.
That is another, grave delusion of PHP users, a natural disaster, a catastrophe:
Even when utilizing old mysql driver, one should never use bare API functions in their code! One have to put them in some library function for the everyday usage! (Not as a some magic rite but just to make the code shorter, less repetitive, error-proof, more consistent and readable).
The same goes for the PDO as well!
Now on with your question again.
but by using them does this eliminate the need to use something like mysql_real_escape_string?
YES.
But I think this is roughly the idea of what should be done to fetch a user from a database
Not to fetch, but to add a whatever data to the query!
you have to given a length after PDO:PARAM_STR if I'm not mistaken
You can, but you don't have to.
Now, is this all safe?
In terms of database safety there are just no weak spots in this code. Nothing to secure here.
for the displaying security - just search this site for the XSS keyword.
Hope I shed some light on the matter.
BTW, for the long inserts you can make some use of the function I wrote someday, Insert/update helper function using PDO
However, I am not using prepared statements at the moment, as I prefer my home-brewed placeholders over them, utilizing a library I mentioned above. So, to counter the code posted by the riha below, it would be as short as these 2 lines:
$sql = 'SELECT * FROM `users` WHERE `name`=?s AND `type`=?s AND `active`=?i';
$data = $db->getRow($sql,$_GET['name'],'admin',1);
But of course you can have the same code using prepared statements as well.
* (yes I am aware of the Schiflett's scaring tales)
I never bother with bindParam() or param types or lengths.
I just pass an array of parameter values to execute(), like this:
$stmt = $dbh->prepare("SELECT * FROM `users` WHERE `id` = :user_id");
$stmt->execute( array(':user_id' => $user_id) );
$stmt = $dbh->prepare("INSERT INTO `users` (username, email)
VALUES (:username, :email)");
$stmt->execute( array(':username'=>$username, ':email'=>$email) );
This is just as effective, and easier to code.
You may also be interested in my presentation SQL Injection Myths and Fallacies, or my book SQL Antipatterns Volume 1: Avoiding the Pitfalls of Database Programming.
Yes, :something is a named placeholder in PDO, ? is an anonymous placeholder. They allow you to either bind values one by one or all at once.
So, basically that makes four options to provide your query with values.
One by one with bindValue()
This binds a concrete value to your placeholder as soon as you call it. You may even bind hard coded strings like bindValue(':something', 'foo') if desired.
Providing a parameter type is optional (but suggested). However, since the default is PDO::PARAM_STR, you only need to specify it when it is not a string. Also, PDO will take care of the length here - there is no length parameter.
$sql = '
SELECT *
FROM `users`
WHERE
`name` LIKE :name
AND `type` = :type
AND `active` = :active
';
$stm = $db->prepare($sql);
$stm->bindValue(':name', $_GET['name']); // PDO::PARAM_STR is the default and can be omitted.
$stm->bindValue(':type', 'admin'); // This is not possible with bindParam().
$stm->bindValue(':active', 1, PDO::PARAM_INT);
$stm->execute();
...
I usually prefer this approach. I find it the cleanest and most flexible.
One by one with bindParam()
A variable is bound to your placeholder that will be read when the query is executed, NOT when bindParam() is called. That may or may not be what you want. It comes in handy when you want to repeatedly execute your query with different values.
$sql = 'SELECT * FROM `users` WHERE `id` = :id';
$stm = $db->prepare($sql);
$id = 0;
$stm->bindParam(':id', $id, PDO::PARAM_INT);
$userids = array(2, 7, 8, 9, 10);
foreach ($userids as $userid) {
$id = $userid;
$stm->execute();
...
}
You only prepare and bind once which safes CPU cycles. :)
All at once with named placeholders
You just drop in an array to execute(). Each key is a named placeholder in your query (see Bill Karwins answer). The order of the array is not important.
On a side note: With this approach you cannot provide PDO with data type hints (PDO::PARAM_INT etc.). AFAIK, PDO tries to guess.
All at once with anonymous placeholders
You also drop in an array to execute(), but it is numerically indexed (has no string keys). The values will replace your anonymous placeholders one by one in the order they appear in your query/array - first array value replaces first placeholder and so forth. See erm410's answer.
As with the array and named placeholders, you cannot provide data type hints.
What they have in common
All of those require you to bind/provide as much values as you have
placeholders. If you bind too many/few, PDO will eat your children.
You don't have to take care about escaping, PDO handles that. Prepared PDO statements are SQL injection safe by design. However, that's not true for exec() and query() - you should generally only use those two for hardcoded queries.
Also be aware that PDO throws exceptions. Those could reveal potentially sensitive information to the user. You should at least put your initial PDO setup in a try/catch block!
If you don't want it to throw Exceptions later on, you can set the error mode to warning.
try {
$db = new PDO(...);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING)
} catch (PDOException $e) {
echo 'Oops, something went wrong with the database connection.';
}
To answer the length question, specifying it is optional unless the param you are binding is an OUT parameter from a stored procedure, so in most cases you can safely omit it.
As far as safety goes, escaping is done behind the scenes when you bind the parameters. This is possible because you had to create a database connection when you created the object. You are also protected from SQL injection attacks since by preparing the statement, you are telling your database the format of the statement before user input can get anywhere near to it. An example:
$id = '1; MALICIOUS second STATEMENT';
mysql_query("SELECT * FROM `users` WHERE `id` = $id"); /* selects user with id 1
and the executes the
malicious second statement */
$stmt = $pdo->prepare("SELECT * FROM `users` WHERE `id` = ?") /* Tells DB to expect a
single statement with
a single parameter */
$stmt->execute(array($id)); /* selects user with id '1; MALICIOUS second
STATEMENT' i.e. returns empty set. */
Thus, in terms of safety, your examples above seem fine.
Finally, I agree that binding parameters individually is tedious and is just as effectively done with an array passed to PDOStatement->execute() (see http://www.php.net/manual/en/pdostatement.execute.php).
This question already has answers here:
How do I create a PDO parameterized query with a LIKE statement?
(9 answers)
Closed 3 years ago.
I am new to PHP, and am trying to learn to use PDO to connect to a test MySQL db. I have the following:
try {
$db = new PDO('mysql:dbname=MYDBNAME;host=MYHOST', 'USERNAME', 'PASSWORD');
$query = "select * from books where ? like '%?%'";
$stmt = $db->prepare($query);
$stmt->execute(array($searchtype, $searchterm));
} catch(PDOException $e) {
echo 'PDOException: ' . $e->getMessage();
}
When I try it I get the following warning:
Warning: PDOStatement::execute() [pdostatement.execute]: SQLSTATE[HY093]: Invalid parameter number: number of bound variables does not match number of tokens
When I remove the like clause, and the $searchterm param, it returns the result properly. I thought -- like '%?%' -- might not be a legal way to create this query under double quotes, so I tried escaping ', which did not work. I looked around for a solution, and found that someone moved '% and %' down to where $searchterm is:
$query = "select * from books where ? like ?";
...
$stmt->execute(array($searchtype, '\'%'.$searchterm.'%\''));
I got the same result.
Any help is appreciated. Thanks!
/ UPDATE ****/
I found on example 12 of http://us3.php.net/manual/en/pdo.prepared-statements.php
Example #12 Invalid use of placeholder
<?php
$stmt = $dbh->prepare("SELECT * FROM REGISTRY where name LIKE '%?%'");
$stmt->execute(array($_GET['name']));
// Below is What they suggest is the correct way.
// placeholder must be used in the place of the whole value
$stmt = $dbh->prepare("SELECT * FROM REGISTRY where name LIKE ?");
$stmt->execute(array("%$_GET[name]%"));
?>
I tried this, and even though I no longer get a Warning, I do not get any results. However when I execute the query directly I will get a couple of results. Any thoughts?
Don't add the quotes when binding prepared variables and dont bind the column name
$query = sprintf( "select * from books where %s like ?", $searchtype );
...
$stmt->execute(array($searchtype, '%'.$searchterm.'%'));
$stmt->execute(array($searchtype, '\'%'.$searchterm.'%\''));
This isn't how parameterised queries work. Inserted parameters act as literal strings already, you don't have to add quote delimiters around them or escape them (that's the whole point), and if you try, you're literally comparing against the string single-quote-searchterm-single-quote.
Consequently if you are (as I suspect) intending to compare a particular column against a literal string, you don't parameterise the column name. At the moment you are comparing a literal string to another literal string, so it'll either always be true or always false regardless of the data in the row!
So I think what you probably mean is:
$query= "SELECT * FROM books WHERE $searchtype LIKE ?";
$like= "%$searchterm%";
$stmt->execute(array($like));
thought naturally you will have to be very careful that $searchtype is known-good to avoid SQL-injection. Typically you would compare it against a list of acceptable column names before using it.
(Aside: there is a way of putting arbitrary strings in a schema name that you can use for a column, but it's annoying, varies across databases and there isn't a standard escaping function for it. In MySQL, you backslash-escape the backquote character, quotes and backslashes and surround the name with backquotes. In ANSI SQL you use double-quotes with doubled-double-quotes inside. In SQL Server you use square brackets. However in reality you vary rarely need to do any of this because really you only ever want to allow a few predefined column names.)
(Another aside: if you want to be able to allow $searchterm values with literal percents, underlines or backslashes in—so users can search for “100%” without matching any string with 100 in—you have to use an explicit escape character, which is a bit tedious:)
$query= "SELECT * FROM books WHERE $searchtype LIKE ? ESCAPE '+'";
$like= str_replace(array('+', '%', '_'), array('++', '+%', '+_'), $searchterm);
$stmt->execute(array("%$like%"));
The problem I see is if you had written a wrapper for PDO, then you would have to somehow handle this separately. The answer I had found and loved was write your query and concat the % to the parameter. i.e. "WHERE column like concat('%', :something, '%')"