I have imported the ESAPI libraries and try to use the following code in jsp -
<s:set var="varUrl" value="%{'<>'}" />
<s:property value="varUrl" />
<esapi:encodeForHTML><s:property value="varUrl"/></esapi:encodeForHTML>
The above code is working fine and I can see the encoded special chars in the browser.
Now when I try this code -
<input type="hidden" name="test" value="<%=ESAPI.encoder().encodeForHTML("<>")%>"/>
Here in this above line the output is not encoded. It shows plain <>.
Does anyone know the reason? Am I not using this the right way? Please suggest.
I am following this link - Using ESAPI in JSP
The encoding is working as expected. Actually I did a mistake of using the IE debugger to check the encoded values. The IE debugger showed inconsistent encoded values. The best way to check if the symbols are encoded or not is to view the page source. And that is what I did now. The values are encoded as expected.
Consider this form:
<form action="http://www.blabla.com?a=1&b=2" method="GET">
<input type="hidden" name="c" value="3" />
</form>
When submitting this GET form, the parameters a and b are disappearing.
Is there a reason for that?
Is there a way of avoiding this behaviour?
Isn't that what hidden parameters are for to start with...?
<form action="http://www.example.com" method="GET">
<input type="hidden" name="a" value="1" />
<input type="hidden" name="b" value="2" />
<input type="hidden" name="c" value="3" />
<input type="submit" />
</form>
I wouldn't count on any browser retaining any existing query string in the action URL.
As the specifications (RFC1866, page 46; HTML 4.x section 17.13.3) state:
If the method is "get" and the action is an HTTP URI, the user agent takes the value of action, appends a `?' to it, then appends the form data set, encoded using the "application/x-www-form-urlencoded" content type.
Maybe one could percent-encode the action-URL to embed the question mark and the parameters, and then cross one's fingers to hope all browsers would leave that URL as it (and validate that the server understands it too). But I'd never rely on that.
By the way: it's not different for non-hidden form fields. For POST the action URL could hold a query string though.
In HTML5, this is per-spec behaviour.
See Association of controls and forms - Form submission algorithm.
Look at "4.10.22.3 Form submission algorithm", step 17. In the case of a GET form to an http/s URI with a query string:
Let destination be a new URL that is equal to the action except that
its <query> component is replaced by query (adding a U+003F QUESTION
MARK character (?) if appropriate).
So, your browser will trash the existing "?..." part of your URI and replace it with a new one based on your form.
In HTML 4.01, the spec produces invalid URIs - most browsers didn't actually do this though...
See Forms - Processing form data, step four - the URI will have a ? appended, even if it already contains one.
What you can do is using a simple foreach on the table containing the GET information. For example in PHP :
foreach ($_GET as $key => $value) {
$key = htmlspecialchars($key);
$value = htmlspecialchars($value);
echo "<input type='hidden' name='$key' value='$value'/>";
}
As the GET values are coming from the user, we should escape them before printing on screen.
You should include the two items (a and b) as hidden input elements as well as C.
I had a very similar problem where for the form action, I had something like:
<form action="http://www.example.com/?q=content/something" method="GET">
<input type="submit" value="Go away..." />
</form>
The button would get the user to the site, but the query info disappeared so the user landed on the home page rather than the desired content page. The solution in my case was to find out how to code the URL without the query that would get the user to the desired page. In this case my target was a Drupal site, so as it turned out /content/something also worked. I also could have used a node number (i.e. /node/123).
If you need workaround, as this form can be placed in 3rd party systems, you can use Apache mod_rewrite like this:
RewriteRule ^dummy.link$ index.php?a=1&b=2 [QSA,L]
then your new form will look like this:
<form ... action="http:/www.blabla.com/dummy.link" method="GET">
<input type="hidden" name="c" value="3" />
</form>
and Apache will append 3rd parameter to query
When the original query has array, for php:
foreach (explode("\n", http_build_query($query, '', "\n")) as $keyValue) {
[$key, $value] = explode('=', $keyValue, 2);
$key = htmlspecialchars(urldecode($key), ENT_COMPAT | ENT_HTML5);
$value = htmlspecialchars(urldecode($value), ENT_COMPAT | ENT_HTML5);
echo '<input type="hidden" name="' . $key . '" value="' . $value . '"' . "/>\n";
}
To answer your first question yes the browser does that and the reason is
that the browser does not care about existing parameters in the action URL
so it removes them completely
and to prevent this from happening use this JavaScript function that I wrote
using jQuery in:
function addQueryStringAsHidden(form){
if (form.attr("action") === undefined){
throw "form does not have action attribute"
}
let url = form.attr("action");
if (url.includes("?") === false) return false;
let index = url.indexOf("?");
let action = url.slice(0, index)
let params = url.slice(index);
url = new URLSearchParams(params);
for (param of url.keys()){
let paramValue = url.get(param);
let attrObject = {"type":"hidden", "name":param, "value":paramValue};
let hidden = $("<input>").attr(attrObject);
form.append(hidden);
}
form.attr("action", action)
}
My observation
when method is GET and form is submitted, hidden input element was sent as query parmater. Old params in action url were wiped out. So basically in this case, form data is replacing query string in action url
When method is POST, and form is submitted, Query parameters in action url were intact (req.query) and input element data was sent as form data (req.body)
So short story long, if you want to pass query params as well as form data, use method attribute as "POST"
This is in response to the above post by Efx:
If the URL already contains the var you want to change, then it is added yet again as a hidden field.
Here is a modification of that code as to prevent duplicating vars in the URL:
foreach ($_GET as $key => $value) {
if ($key != "my_key") {
echo("<input type='hidden' name='$key' value='$value'/>");
}
}
Your construction is illegal. You cannot include parameters in the action value of a form. What happens if you try this is going to depend on quirks of the browser. I wouldn't be surprised if it worked with one browser and not another. Even if it appeared to work, I would not rely on it, because the next version of the browser might change the behavior.
"But lets say I have parameters in query string and in hidden inputs, what can I do?" What you can do is fix the error. Not to be snide, but this is a little like asking, "But lets say my URL uses percent signs instead of slashes, what can I do?" The only possible answer is, you can fix the URL.
I usually write something like this:
foreach($_GET as $key=>$content){
echo "<input type='hidden' name='$key' value='$content'/>";
}
This is working, but don't forget to sanitize your inputs against XSS attacks!
<form ... action="http:/www.blabla.com?a=1&b=2" method ="POST">
<input type="hidden" name="c" value="3" />
</form>
change the request method to' POST' instead of 'GET'.
I am passing some param with value from my JSP file and before that I am using Apache StringEscapeUtils to avoid any XSS attack script execution using param value
for example, if somebody inserting value like this and gain access
Cross script test is currently failing when something like this is passed as value
site_locale=en_US%2F%3E%3Ciframe+src%3Djavascript%3Aalert%28116%29+
Blind SQL Injection test is currently failing when something like this is passed
isMgr=true%27+and+%27f%27%3D%27f%27%29+--+
My question here is whether StringEscapeUtils.escapeHtml will save from above type of param value passed or do i need any other library
I also wanted to confirm if the way I am calling StringEscapeUtils in JSP is correct or not
<input type="hidden" name="site_locale" value= <%= StringEscapeUtils.escapeHtml(site_locale) %> >
Appreciate any pointers here
Thanks
Try this.
Utility class for HTML form encoding
URLEncoder.encode(yoururlhere, "UTF-8")
Similar way, we have
java.net.URLDecoder.decode(yoururlhere, "UTF-8");
I did a hello world web application in Java on Tomcat container. I have a query string
code=askdfjlskdfslsjdflksfjl#_=_
with underscores on both sides of = in the URL. When I tried to retrieve the query string in the servlet by request.getParameter("code"), I get only askdfjlskdfslsjdflksfjl. The part after # is missing.
How is this caused and how can I solve it?
That's because the part of the url after # is not a part of the query.
Section 3.4 of approprate RFC says:
The query component is indicated by the first question
mark ("?") character and terminated by a number sign ("#") character
or by the end of the URI.
The # is only interpreted by the browser, not the server. If you want to pass the # character to the server, you must URLEncode it.
Example:
URLEncoder.encode("code=askdfjlskdfslsjdflksfjl#=", "UTF-8");
Please read the percent encoding on Wikipedia. The # and = are reserved characters in URLs. Only unreserved characters can be used plain in URLs, all other characters are supposed to be URL-encoded. The URL-encoded value of a # is %23 and = is %3D. So this should do:
code=askdfjlskdfslsjdflksfjl%23_%3D_
If this actually originates from a HTML <a> link in some JSP like so:
some link
then you should actually have changed it to use JSTL's <c:url>:
<c:url var="servletUrlWithParam" value="servletUrl">
<c:param name="code" value="askdfjlskdfslsjdflksfjl#_=_" />
</c:url>
some link
so that it get generated as
some link
Note that this is not related to Java/Servlets per-se, this applies to every web application.
I have a JAVA with JSF/ICEFaces application. I need to pass parameters from one page to another so I user something like:
<f:param name="eventName" value="#{item.event_name}" />
And then get it in the constructor using:
eventName = request.getParameter("eventName");
While works fine unless there is a '/' character in the string submitted, it doesn't get parsed properly. I believe I need to escape the '/' parameter with %2F and then parse it back.
Two things:
1- How to do this in ICEFaces or JSF
2- Are there other parameter I have to escape?
Thanks,
Tam
<h:outputLink value="http://google.com">click
<f:param name="eventName" value="#{param.eventName}" />
</h:outputLink>
works for me - the browser takes care of url-encoding.
Note that you can get request parameters directly in your page, using #{param.paramName}