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| Input and Security Class | |
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| <h1>Input Class</h1> | |
| <p>The Input Class serves two purposes:</p> | |
| <ol> | |
| <li>It pre-processes global input data for security.</li> | |
| <li>It provides some helper functions for fetching input data and pre-processing it.</li> | |
| </ol> | |
| <p class="important"><strong>Note:</strong> This class is initialized automatically by the system so there is no need to do it manually.</p> | |
| <h2>Security Filtering</h2> | |
| <p>The security filtering function is called automatically when a new <a href="../general/controllers.html">controller</a> is invoked. It does the following:</p> | |
| <ul> | |
| <li>Destroys the global GET array. Since CodeIgniter does not utilize GET strings, there is no reason to allow it.</li> | |
| <li>Destroys all global variables in the event register_globals is turned on.</li> | |
| <li>Filters the POST/COOKIE array keys, permitting only alpha-numeric (and a few other) characters.</li> | |
| <li>Provides XSS (Cross-site Scripting Hacks) filtering. This can be enabled globally, or upon request.</li> | |
| <li>Standardizes newline characters to \n</li> | |
| </ul> | |
| <h2>XSS Filtering</h2> | |
| <p>CodeIgniter comes with a Cross Site Scripting Hack prevention filter which can either run automatically to filter | |
| all POST and COOKIE data that is encountered, or you can run it on a per item basis. By default it does <strong>not</strong> | |
| run globally since it requires a bit of processing overhead, and since you may not need it in all cases.</p> | |
| <p>The XSS filter looks for commonly used techniques to trigger Javascript or other types of code that attempt to hijack cookies | |
| or do other malicious things. If anything disallowed is encountered it is rendered safe by converting the data to character entities.</p> | |
| <p> | |
| Note: This function should only be used to deal with data upon submission. It's not something that should be used for general runtime processing since it requires a fair amount of processing overhead.</p> | |
| <p>To filter data through the XSS filter use this function:</p> | |
| <h2>$this->input->xss_clean()</h2> | |
| <p>Here is an usage example:</p> | |
| <code>$data = $this->input->xss_clean($data);</code> | |
| <p>If you want the filter to run automatically every time it encounters POST or COOKIE data you can enable it by opening your | |
| <kbd>application/config/config.php</kbd> file and setting this:</p> | |
| <code>$config['global_xss_filtering'] = TRUE;</code> | |
| <p>Note: If you use the form validation class, it gives you the option of XSS filtering as well.</p> | |
| <h2>Using POST, COOKIE, or SERVER Data</h2> | |
| <p>CodeIgniter comes with three helper functions that let you fetch POST, COOKIE or SERVER items. The main advantage of using the provided | |
| functions rather then fetching an item directly ($_POST['something']) is that the functions will check to see if the item is set and | |
| return false (boolean) if not. This lets you conveniently use data without having to test whether an item exists first. | |
| In other words, normally you might do something like this:</p> | |
| <code> | |
| if ( ! isset($_POST['something']))<br /> | |
| {<br /> | |
| $something = FALSE;<br /> | |
| }<br /> | |
| else<br /> | |
| {<br /> | |
| $something = $_POST['something'];<br /> | |
| }</code> | |
| <p>With CodeIgniter's built in functions you can simply do this:</p> | |
| <code>$something = $this->input->post('something');</code> | |
| <p>The three functions are:</p> | |
| <ul> | |
| <li>$this->input->post()</li> | |
| <li>$this->input->cookie()</li> | |
| <li>$this->input->server()</li> | |
| </ul> | |
| <h2>$this->input->post()</h2> | |
| <p>The first parameter will contain the name of the POST item you are looking for:</p> | |
| <code>$this->input->post('some_data');</code> | |
| <p>The function returns FALSE (boolean) if the item you are attempting to retrieve does not exist.</p> | |
| <p>The second optional parameter lets you run the data through the XSS filter. It's enabled by setting the second parameter to boolean TRUE;</p> | |
| <code>$this->input->post('some_data', TRUE);</code> | |
| <h2>$this->input->cookie()</h2> | |
| <p>This function is identical to the post function, only it fetches cookie data:</p> | |
| <code>$this->input->cookie('some_data', TRUE);</code> | |
| <h2>$this->input->server()</h2> | |
| <p>This function is identical to the above functions, only it fetches server data:</p> | |
| <code>$this->input->server('some_data');</code> | |
| <h2>$this->input->ip_address()</h2> | |
| <p>Returns the IP address for the current user. If the IP address is not valid, the function will return an IP of: 0.0.0.0</p> | |
| <code>echo $this->input->ip_address();</code> | |
| <h2>$this->input->valid_ip(<var>$ip</var>)</h2> | |
| <p>Takes an IP address as input and returns TRUE or FALSE (boolean) if it is valid or not. Note: The $this->input->ip_address() function above | |
| validates the IP automatically.</p> | |
| <code>if ( ! valid_ip($ip))<br /> | |
| {<br /> | |
| echo 'Not Valid';<br /> | |
| }<br /> | |
| else<br /> | |
| {<br /> | |
| echo 'Valid';<br /> | |
| }</code> | |
| <h2>$this->input->user_agent()</h2> | |
| <p>Returns the user agent (web browser) being used by the current user. Returns FALSE if it's not available.</p> | |
| <code>echo $this->input->user_agent();</code> | |
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