How do we control web page caching, across all bro

2020-01-22 11:01发布

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Our investigations have shown us that not all browsers respect the HTTP cache directives in a uniform manner.

For security reasons we do not want certain pages in our application to be cached, ever, by the web browser. This must work for at least the following browsers:

  • Internet Explorer 6+
  • Firefox 1.5+
  • Safari 3+
  • Opera 9+
  • Chrome

Our requirement came from a security test. After logging out from our website you could press the back button and view cached pages.

26条回答
啃猪蹄的小仙女
2楼-- · 2020-01-22 11:34

I found the web.config route useful (tried to add it to the answer but doesn't seem to have been accepted so posting here)

<configuration>
<system.webServer>
    <httpProtocol>
        <customHeaders>
            <add name="Cache-Control" value="no-cache, no-store, must-revalidate" />
            <!-- HTTP 1.1. -->
            <add name="Pragma" value="no-cache" />
            <!-- HTTP 1.0. -->
            <add name="Expires" value="0" />
            <!-- Proxies. -->
        </customHeaders>
    </httpProtocol>
</system.webServer>

And here is the express / node.js way of doing the same:

app.use(function(req, res, next) {
    res.setHeader('Cache-Control', 'no-cache, no-store, must-revalidate');
    res.setHeader('Pragma', 'no-cache');
    res.setHeader('Expires', '0');
    next();
});
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Root（大扎）
3楼-- · 2020-01-22 11:35

DISCLAIMER: I strongly suggest reading @BalusC's answer. After reading the following caching tutorial: http://www.mnot.net/cache_docs/ (I recommend you read it, too), I believe it to be correct. However, for historical reasons (and because I have tested it myself), I will include my original answer below:

I tried the 'accepted' answer for PHP, which did not work for me. Then I did a little research, found a slight variant, tested it, and it worked. Here it is:

header('Cache-Control: no-store, private, no-cache, must-revalidate');     // HTTP/1.1
header('Cache-Control: pre-check=0, post-check=0, max-age=0, max-stale = 0', false);  // HTTP/1.1
header('Pragma: public');
header('Expires: Sat, 26 Jul 1997 05:00:00 GMT');                  // Date in the past  
header('Expires: 0', false); 
header('Last-Modified: '.gmdate('D, d M Y H:i:s') . ' GMT');
header ('Pragma: no-cache');

That should work. The problem was that when setting the same part of the header twice, if the false is not sent as the second argument to the header function, header function will simply overwrite the previous header() call. So, when setting the Cache-Control, for example if one does not want to put all the arguments in one header() function call, he must do something like this:

header('Cache-Control: this');
header('Cache-Control: and, this', false);

See more complete documentation here.

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放我归山
4楼-- · 2020-01-22 11:35

The headers in the answer provided by BalusC does not prevent Safari 5 (and possibly older versions as well) from displaying content from the browser cache when using the browser's back button. A way to prevent this is to add an empty onunload event handler attribute to the body tag:

<body onunload="">

This hack apparently breaks the back-forward cache in Safari: Is there a cross-browser onload event when clicking the back button?

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放荡不羁爱自由
5楼-- · 2020-01-22 11:36

I had no luck with <head><meta> elements. Adding HTTP cache related parameters directly (outside of the HTML doc) does indeed work for me.

Sample code in Python using web.py web.header calls follows. I purposefully redacted my personal irrelevant utility code.


    import web
    import sys
    import PERSONAL-UTILITIES

    myname = "main.py"

    urls = (
        '/', 'main_class'
    )

    main = web.application(urls, globals())

    render = web.template.render("templates/", base="layout", cache=False)

    class main_class(object):
        def GET(self):
            web.header("Cache-control","no-cache, no-store, must-revalidate")
            web.header("Pragma", "no-cache")
            web.header("Expires", "0")
            return render.main_form()

        def POST(self):
            msg = "POSTed:"
            form = web.input(function = None)
            web.header("Cache-control","no-cache, no-store, must-revalidate")
            web.header("Pragma", "no-cache")
            web.header("Expires", "0")
            return render.index_laid_out(greeting = msg + form.function)

    if __name__ == "__main__":
        nargs = len(sys.argv)
        # Ensure that there are enough arguments after python program name
        if nargs != 2:
            LOG-AND-DIE("%s: Command line error, nargs=%s, should be 2", myname, nargs)
        # Make sure that the TCP port number is numeric
        try:
            tcp_port = int(sys.argv[1])
        except Exception as e:
            LOG-AND-DIE ("%s: tcp_port = int(%s) failed (not an integer)", myname, sys.argv[1])
        # All is well!
        JUST-LOG("%s: Running on port %d", myname, tcp_port)
        web.httpserver.runsimple(main.wsgifunc(), ("localhost", tcp_port))
        main.run()
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放我归山
6楼-- · 2020-01-22 11:39 
//In .net MVC
[OutputCache(NoStore = true, Duration = 0, VaryByParam = "*")]
public ActionResult FareListInfo(long id)
{
}

// In .net webform
<%@ OutputCache NoStore="true" Duration="0" VaryByParam="*" %>
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干净又极端
7楼-- · 2020-01-22 11:40

I've had best and most consistent results across all browsers by setting Pragma: no-cache

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