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Is it possible to write an IIS Module in C++ that is compiled 32bit?

Smith, Roland 40 Reputation points
2024-02-08T21:49:27.43+00:00

I've created a Module in C++ which works well so far. The problem I have is that I'd like to have it be 32bit. I compile the DLL as 64-bit and it works fine. I compile as 32-bit and edit applicationHost.config and change preConditions to bitness32 or remove preConditions and it fails. Is it possible or am I missing something? Current entries in applicationHost.config (working 64-bit) that were added by IIS Manager:

<globalModules>
    <add name="TopwizWebModule" image="C:\source\repos\TopwizWebModule\x64\Release\TopwizWebModule.dll" preCondition="bitness64" />
</globalModules>

<handlers accessPolicy="Read, Execute, Script">
    <add name="TopwizWebModule" path="*.topwiz" verb="*" modules="TopwizWebModule" resourceType="File" preCondition="bitness64,winx86_64" />
</handlers>

<modules>
    <add name="TopwizWebModule" preCondition="bitness64" />
</modules>
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  1. XuDong Peng-MSFT 10,341 Reputation points Microsoft Vendor
    2024-02-09T02:09:37.1766667+00:00

    Hi @Smith, Roland，

    Is it possible or am I missing something?

    I think you may have forgotten to set Enable 32-Bit Application to True for the IIS application pool, so that the web application and the dll run at the same bitness.

    User's image

    Best regards,

    Xudong Peng

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  1. Lex Li (Microsoft) 5,322 Reputation points Microsoft Employee
    2024-02-09T05:46:51.8333333+00:00

    First, you will have to prove that you did compile the code to a 32 bit library. Use a tool from Visual Studio command prompt like dumpbin to verify https://learn.microsoft.com/en-us/cpp/build/reference/dumpbin-command-line?view=msvc-170

    Second, I suggest you put 32-bit and 64-bit library files to IIS installation folders (32 bit in %windir%\sysWOW64\inetsrv and 64 bit in %windir%\system32\inetsrv and then registered in <globalModules> as <add name="TopwizWebModule" image="%windir%\System32\inetsrv\TopwizWebModule.dll" />.

    Finally, you can enable the module in your site/application by adding it to <modules> like <add name="TopwizWebModule" />.