I am not sure if rundll will run all the functions in a dll, only those with a winmain like signiture. Possibly I am quoting out of context but the rundll does seem to be what you want to do
The Run DLL utility (Rundll32.exe) included in Windows enables you to call functions exported from a 32-bit DLL. These functions must have the following syntax:
void CALLBACK EntryPoint(
HWND hwnd, // handle to owner window
HINSTANCE hinst, // instance handle for the DLL
LPTSTR lpCmdLine, // string the DLL will parse
int nCmdShow // show state
);
Typically, you would not run a dll by itself, but an application would make calls on functions in the dll. Running the dll by itself usually does not produce the same effect as the application. The application has an overall purpose defined in its main entry point. What Leo says is true. If you want to see the overall purpose of a dll then you should compile your source to an exe, where the main entry point has the word "main" in it, usually.
In you are working with a .net dll, then you can get a list of all the functions in the dll using VS or "C:\Program Files\Microsoft Visual Studio .NET\FrameworkSDK\Bin\Ildasm.exe"
For non .net dlls, I think you can use a Windows exe tool to extract a list of functions within a dll. Google the windows exe tools.
After you get the function name, if it is in .net then you can rebuild the .net dll to an exe with "C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\AL.ex e" and specify one of the functions as the entry point (what about parameter list :eusa_thin) You do not need source code. Note that you might not get any purpose from just the one function call unless it was written with an overall purpose, eg, something that would be typically hosted in a process.
If the function is not in a .Net dll but you are using VB.net then, use VS to compile a new exe aplication and import the dll and rewrite the function entry point. Then call it from within main and build a new exe application.
VB.Net
<DllImport("KERNEL32.DLL", EntryPoint := "MoveFileW", _
SetLastError := True, CharSet := CharSet.Unicode, _
ExactSpelling := True, _
CallingConvention := CallingConvention.StdCall)> _
Public Shared Function MoveFile(src As String, dst As String) As Boolean
' Leave function empty - DLLImport attribute forwards calls to MoveFile to
' MoveFileW in KERNEL32.DLL.
End Function
Public Main ...
If you want to see the functions that are listed in dlls in the Windows directory, then check msdn documentation. I will try to look up the tool that list them, but do a google. You can also get documentation on their functionality.
Please forgive me of any errors and correct me.