Download a file from a permalink URL, and not a direct exe url

So I am using InnoSetup 6 which natively supports downloading files from the internet during installation. I have figured out downloading files given a direct link, from this thread Inno Setup: Install file from Internet

However, I can't for the life of me figure out how to download the latest version of a file given a permalink URL. My specific example is to download the Microsoft Hosting package. https://dotnet.microsoft.com/permalink/dotnetcore-current-windows-runtime-bundle-installer

Going to this page automatically downloads the latest package. Inno doesn't like this link (or I don't know how to get Inno to use it) since it doesn't point to the direct file. If I use the direct link (https://download.visualstudio.microsoft.com/download/pr/24847c36-9f3a-40c1-8e3f-4389d954086d/0e8ae4f4a8e604a6575702819334d703/dotnet-hosting-5.0.6-win.exe) this works for obvious reasons.

I'd like to always download the latest, but I'm not sure how to accomplish this. Any suggestions? Adding super basic code being used...

DownloadPage.Clear;
DownloadPage.Add('https://dotnet.microsoft.com/permalink/dotnetcore-current-windows-runtime-bundle-installer', 'dotnet-hosting.exe', '');
DownloadPage.Show;

Solution

Without realizing it you are asking two different question here. That is because these "permalinks" aren't really permalinks but redirects to some dynamic resource that has a link to what you are looking for.

So first, addressing the Microsoft "permalink", you need to realize that under the hood you are accessing a URL that redirects to some page which will point to the latest. Then under the hood, that page invokes a JavaScript function, IF YOU ACCESSING VIA A WEB BROWSER, to download the installer. Note that both the page pointed to and the code to invoke the installer WILL eventually change. In fact, the code itself logs a "warning" when people attempt to download directly:

If you do a view source you'll see:

    <script>
        $(function () {
            recordDownload('.NET', 'runtime-aspnetcore-5.0.6-windows-hosting-bundle-installer');
            window.open("https://download.visualstudio.microsoft.com/download/pr/24847c36-9f3a-40c1-8e3f-4389d954086d/0e8ae4f4a8e604a6575702819334d703/dotnet-hosting-5.0.6-win.exe", "_self");
        });

        function recordManualDownload() {
            ga("send", "event", "Download.Warning", "Direct Link Used", "runtime-aspnetcore-5.0.6-windows-hosting-bundle-installer");
        }
    </script>

So you can download the HTML from this page and use some regex to get the directo downloadlink but beware, the link is going to change every time Microsoft releases a new version. Furthermore, WHEN (not if but when) MS decides to rebrand this entire process might break. So the best you can do here is try to download the html and try parse the download URL from this "permalink"

As an alternative. you can to download the latest DotNet powershell install script as described here.

If possible, execute that script directly. If not look at the function Get-AkaMSDownloadLink within the install script to see how it builds the url to get the latest version. You would probably be better served using that building and using that URL as opposed to attempting to download from some arbitrary HTML code.

Now, onto the second question you might not have realized your were asking is how to automate this for any random installer. The answer is you can't. Some might have a permalink that directly points to the latest but you are always going to find cases like Microsoft. Best you can down is hard code some links in some service, as @martin-prikryl suggested, and when the break update the links in those services.