I'm creating my own (multi threaded) ISAPI based website in C++ and I'm trying to implement correct session management.
The problem is that when a new session should be created, the session is created twice when using subsequent requests in the generated web page.
Here's how it works:
- Client requests http://localhost and sends either no cookie or a cookie with an old session ID in it.
- Server looks at the session cookie and feels that it needs to create a new one because it no longer exists: it prepares a header with a cookie in it with a new session ID and sends the complete header to the client (I tracked this with http live headers plugin in firefox and it is correct). It also prepares some data like the page and and stuff like that (not yet body data, as it is still processing data from the database and stuff like that) and sends what it has back to the client.
- Client should have this new session cookie now, and sees the stylesheet link and immediately sends the stylesheet request http://localhost/css to my server. But... he still does this with the old session ID for some reason, not with the newly received one!
- Server sees this request (with again an no longer existing session id), generates another new session and sends the new session id with a cookie along with the stylesheet data.
So the client has received two session id's now and will from now on keep using the second one as the first one is overwritten, but nevertheless the first page has used the wrong session (or actually, the second page has).
You could say that this is not a problem, but when I start using personalized stylesheets, I will have the wrong stylesheet on the first page and as the page will use AJAX to refresh the content (if available), it is possible that the stylesheet is never reloaded unless the client refreshes.
So, is this a problem that is always there when doing this kind of thing? Will the browser always send an old cookie although it has already received a new one but is still processing the page? Is this a problem that, for example PHP, also has?
Note: before all the discussions start about "use php instead" or something: I am rewriting a website that I had first written in PHP, it became popular, had thousands of (real) visitors every hour and started killing my server (the website doesn't make that kind of money that I can throw lots of servers at it). By writing it in C++, requests take 2ms instead of 200ms in PHP... I can optimize everything. By taking my time to develop this ISAPI correctly, it is safely multi-threaded and can be multi-processed, multi-servered. And most of all, I like the challenge.
Added note: It seems that the problem is only there when an old session exists in the cookies, because when I completely clear all cookies from my browser, and a new one is created and sent back to the client, the subsequent stylesheet request immediately uses the given session id. This seems to be some kind of proof that I'm doing something wrong when an old session id is sent... Should an existing cookie be deleted first? How?
Added note: The cookie is written with an expire-date one year ahead.
I have found out what the problem was, I was in the assumption that setting a cookie without specifying a path would result in making the session work on all paths on that domain.
By using http://foo.bar/home as main page and http://foo.bar/home/css as stylesheet, internally translating that url to ?s1=home and ?s1=home&css=y, I was actually using two different paths according to the browser which did not pass the cookie to the css-request.
For some reason, they actually got together afterwards, I don't fully understand why.
Isn't this silly? Will people not often have a http://foo.bar/index.php and a http://foo.bar/css/style.css.php , just because they use subdirectories to keep their structure clean?
If anyone knows of a way to fix it, to make subpaths also work with the same cookies, let me know, but as I understand it from the definition of cookies, they are stuck within a specific path (although, it seems that if you specifically add a path other than /, it will work on subdirectories as well?)
Related
I've just noticed my console is littered with this warning, appearing for every single linked resource. This includes all referenced CSS files, javascript files, SVG images, and even URLs from ajax calls (which respond in JSON). But not images.
The warning, for example in case of a style.css file, will say:
Cookie “PHPSESSID” will be soon treated as cross-site cookie against “http://localhost/style.css” because the scheme does not match.
But, the scheme doesn't match what? The document? Because that it does.
The URL of my site is http://localhost/.
The site and its resources are all on http (no https on localhost)
The domain name is definitely not different because everything is referenced relative to the domain name (meaning the filepaths start with a slash href="/style.css")
The Network inspector just reports a green 200 OK response, showing everything as normal.
It's only Mozilla Firefox that is complaining about this. Chromium seems to not be concerned by anything. I don't have any browser add-ons. The warnings seem to originate from the browser, and each warning links to view the corresponding file source in Debugger.
Why is this appearing?
that was exactly same happening with me. the issue was that, firefox keeps me showing even Cookies of different websites hosted on same URL : "localhost:Port number" stored inside browser memory.
In my case, i have two projects configured to run at http://localhost:62601, when i run first project, it saves that cookie in browser memory. when i run second project having same URL, Cookie is available inside that projects console also.
what you can do, is delete the all of the cookies from browser.
#Paramjot Singh's answer is correct and got me most of the way to where I needed to be. I also wasted a lot of time staring at those warnings.
But to clarify a little, you don't have to delete ALL of your cookies to resolve this. In Firefox, you can delete individual site cookies, which will keep your settings on other sites.
To do so, click the hamburger menu in the top right, then, Options->Privacy & Security or Settings->Privacy & Security
From here, scroll down about half-way and find Cookies and Site Data. Don't click Clear Data. Instead, click Manage Data. Then, search for the site you are having the notices on, highlight it, and Remove Selected
Simple, I know, but I made the mistake of clearing everything the first time - maybe this will prevent someone from doing same.
The warning is given because, according to MDN web docs:
Standards related to the Cookie SameSite attribute recently changed such that:
The cookie-sending behaviour if SameSite is not specified is SameSite=Lax. Previously the default was that cookies were sent for all requests.
Cookies with SameSite=None must now also specify the Secure attribute (they require a secure context/HTTPS).
Which indicates that a secure context/HTTPS is required in order to allow cross site cookies by setting SameSite=None Secure for the cookie.
According to Mozilla, you should explicitly communicate the intended SameSite policy for your cookie (rather than relying on browsers to apply SameSite=Lax automatically), otherwise you might get a warning like this:
Cookie “myCookie” has “SameSite” policy set to “Lax” because it is missing a “SameSite” attribute, and “SameSite=Lax” is the default value for this attribute.
The suggestion to simply delete localhost cookies is not actually solving the problem. The solution is to properly set the SameSite attribute of cookies being set by the server and use HTTPS if needed.
Firefox is not the only browser making these changes. Apparently the version of Chrome I am using (84.0.4147.125) has already implemented the changes as I got this message in the console:
The previously mentioned MDN article and this article by Mike Conca have great information about changes to SameSite cookie behavior.
Guess you are using WAMP or LAMP etc. The first thing you need to do is enable ssl on WAMP as you will find many references saying you need to adjust the cookie settings to SameSite=None; Secure That entails your local connection being secure. There are instructions on this link https://articlebin.michaelmilette.com/how-to-add-ssl-https-to-wampserver/ as well as some YouTube vids.
The important thing to note is that when creating the SSL certificate you should use sha256 encoding as sha1 is now deprecated and will throw another warning.
There is a good explanation of SameSite cookies on https://web.dev/samesite-cookies-explained/
I was struggling with the same issue and solved it by making sure the Apache 2.4 headers module was enabled and than added one line of code
Header always edit Set-Cookie ^(.")$ $1;HttpOnly;Secure
I wasted lots of time staring at the same sets of warnings in the Inspector until it dawned on me that the cookies were persisting and needed purging.
Apparently Chrome was going to introduce the new rules by now but Covid-19 meant a lot of websites might have been broken while people worked from home. The major browsers are working together on the SameSite attribute this so it will be in force soon.
I've been looking on the web regarding CORS, and I wanted to confirm if whatever I made of it is, what it actually is.
Mentioned below is a totally fictional scenario.
I'll take an example of a normal website. Say my html page has a form that takes a text field name. On submitting it, it sends the form data to myPage.php. Now, what happens internally is that, the server sends the request to www.mydomain.com/mydirectory/myPage.php along with the text fields. Now, the server sees that the request was fired off from the same domain/port/protocol
(Question 1. How does server know about all these details. Where does it extract all these details froms?)
Nonetheless, since the request is originated from same domain, it server the php script and returns whatever is required off it.
Now, for the sake of argument, let's say I don't want to manually fill the data in text field, but instead I want to do it programmatically. What I do is, I create a html page with javascript and fire off a POST request along with the parameters (i.e. values of textField). Now since my request is not from any domain as such, the server disregards the service to my request. and I get cross domain error?
Similarly, I could have written a Java program also, that makes use of HTTPClient/Post request and do the same thing.
Question 2 : Is this what the problem is?
Now, what CORS provide us is, that the server will say that 'anyone can access myPage.php'.
From enable cors.org it says that
For simple CORS requests, the server only needs to add the following header to its response:
Access-Control-Allow-Origin: *
Now, what exactly is the client going to do with this header. As in, the client anyway wanted to make call to the resources on server right? It should be upto server to just configure itself with whether it wants to accept or not, and act accordingly.
Question 3 : What's the use of sending a header back to client (who has already made a request to the server)?
And finally, what I don't get is that, say I am building some RESTful services for my android app. Now, say I have one POST service www.mydomain.com/rest/services/myPost. I've got my Tomcat server hosting these services on my local machine.
In my android app, I just call this service, and get the result back (if any). Where exactly did I use CORS in this case. Does this fall under a different category of server calls? If yes, then how exactly.
Furthermore, I checked Enable Cors for Tomcat and it says that I can add a filter in my web.xml of my dynamic web project, and then it will start accepting it.
Question 4 : Is that what is enabling the calls from my android device to my webservices?
Thanks
First of all, the cross domain check is performed by the browser, not the server. When the JavaScript makes an XmlHttpRequest to a server other than its origin, if the browser supports CORS it will initialize a CORS process. Or else, the request will result in an error (unless user has deliberately reduced browser security)
When the server encounters Origin HTTP header, server will decide if it is in the list of allowed domains. If it is not in the list, the request will fail (i.e. server will send an error response).
For number 3 and 4, I think you should ask separate questions. Otherwise this question will become too broad. And I think it will quickly get close if you do not remove it.
For an explanation of CORS, please see this answer from programmers: https://softwareengineering.stackexchange.com/a/253043/139479
NOTE: CORS is more of a convention. It does not guarantee security. You can write a malicious browser that disregards the same domain policy. And it will execute JavaScript fetched from any site. You can also create HTTP headers with arbitrary Origin headers, and get information from any third party server that implements CORS. CORS only works if you trust your browser.
For question 3, you need to understand the relationship between the two sites and the client's browser. As Krumia alluded to in their answer, it's more of a convention between the three participants in the request.
I recently posted an article which goes into a bit more detail about how CORS handshakes are designed to work.
Well I am not a security expert but I hope, I can answer this question in one line.
If CORS is enabled then server will just ask browser if you are calling the request from [xyz.com]? If browser say yes it will show the result and if browser says no it is from [abc.com] it will throw error.
So CORS is dependent on browser. And that's why browsers send a preflight request before actual request.
In my case I just added
.authorizeRequests().antMatchers(HttpMethod.OPTIONS, "/**").permitAll()
to my WebSecurityConfiguration file issue is resolved
I am confused about how cookies are set. It seems that cookies can be sent in the request header, even after I have deleted them all.
What I do:
In IE: delete all cookies (wrench-thing->safety->delete browsing history-> check all, except preserve favorites-> Delete)
Go to random site (google.com) and open the Network tab (F12/Network) - because it won't open from blank tab.
Make sure browsing history persists (tools-> clear entries on navigate-> uncheck both)
Click "Start capturing"
Go to site: http://www.klm.com/travel/dk_da/index.htm
Look at Network data. For the first url (http://www.klm.com/travel/dk_da/index.htm ), click "Go to detailed view". Click "cookies"
I look at the cookie that is being sent (in Cookies tab or under 'Request headers') and it's already sending 7 values, for example, EBT_JSESSIONID. But, where do these values come from? I haven't received anything at this point. I realize that cookies can be set via javascript, but I haven't loaded any js at this point either.
I am trying to figure this out as part of webscrabing. Really want to be able to do it without Selenium or the like, and need to generate/use the various IDs that are being passed around the various calls.
Using chrome in Mac we had this issue and restarting the browser did solve the issue. The scenario was weird because the value was being sent only for one specific HTML.
I have created a basic but extensive javascript-html page that depends on cookies to keep user information. It runs perfectly on my computer (MAC - Firefox) but when loaded into my hosted web site (the page is in my domain) the cookies are not being written when the page is opened.
I was hoping that by keeping all the programming in javascript I could get some basic interactivity. Is this assumption wrong? Must the cookies be written using PHP?
My cookie writes are very vanilla.
document.cookie = cookieArray[ja]+expires+"; path=/"; // writes cookie data into browser.
update
well cookies are now being written since I added "path=/; domain=.my.org". But now there is one other problem.
It seems that safari and Firefox write the cookies in reverse order to each other. I create the cookies by altering an array then simply stepping thru the array to write the cookies. I was hoping that I could simply read the cookies one by one and keep the order. Ah well.
Did you added the ";" between cookieArray[ja] and expires?
document.cookie = 'cookie-name=cookie-value; expires=Thu, 01-Jan-70 00:00:01 GMT;';
Also the cookieArray[ja] have to contain the cookie-name.
Do you really need the path? This parameter is also optional.
Cookies are, by default, available to all other files in the same directory the cookie was created in.
http://www.comptechdoc.org/independent/web/cgi/javamanual/javacookie.html
I'm stuck in a cookie related question. I want to write a program that can automate download the attachments of this forum. So I should maintain the cookies this site send to me. When I send a GET request in my program to the login page, I got the cookie such as Set-Cookie: sso_sid=0589a967; domain=.it168.com in my program. Now if I use a cookie viewer such as cookie monster and send the same GET request, my program get the same result, but the cookie viewer shows that the site also send me two cookies which are:
testcookie http://get2know.it/myimages/2009-12-27_072438.jpg and token http://get2know.it/myimages/2009-12-27_072442.jpg
My question is: Where did the two cookie came from? Why they did not show in my program?
Thanks.
Your best bet to figure out screen-scraping problems like this one is to use Fiddler. Using Fiddler, you can compare exactly what is going over the wire in your app vs. when accessing the site from a browser. I suspect you'll see some difference between headers sent by your app vs. headers sent by the browser-- this will likley account for the difference you're seeing.
Next, you can do one of two things:
change your app to send exactly the headers that the browser does (and, if you do this, you should get exactly the response that a real browser gets).
using Fiddler's "request builder" feature, start removing headers one by one and re-issuing the request. At some point, you'll remove a header which makes the response not match the response you're looking for. That means that header is required. Continue for all other headers until you have a list of headers that are required by the site to yield the response you want.
Personally, I like option #2 since it requires a minimum amount of header-setting code, although it's harder initially to figure out which headers the site requires.
On your actual question of why you're seeing 2 cookies, only the diagnosis above will tell you for sure, but I suspect it may have to do with the mechanism that some sites use to detect clients who don't accept cookies. On the first request in a session, many sites will "probe" a client to see if the client accepts cookies. Typically they'll do this:
if the request doesn't have a cookie on it, the site will redirect the client to a special "cookie setting" URL.
The redirect response, in addition to having a Location: header which does the redirect, will also return a Set-Cookie header to set the cookie. The redirect will typically contain the original URL as a query string parameter.
The server-side handler for the "cookie setter" page will then look at the incoming cookie. If it's blank, this means that the user's browser is set to not accept cookies, and the site will typically redirect the user to a "sorry, you must use cookies to use this site" page.
If, however, there is a cookie header send to the "cookie setter" URL, then the client does in fact accept cookies, and the handler will simply redirect the client back to the original URL.
The original URL, once you move on to the next page, may add an additional cookie (e.g. for a login token).
Anyway, that's one way you could end up with two cookies. Only diagnosis with Fiddler (or a similar tool) will tell you for sure, though.