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AlexP



Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.
AlexP
I have a function that performs both encryption and decryption the same, but to conform to the others I would like to have two names for it, one for both encryption and decryption. Could I do this?:
Code:
export 'MyDLL.dll',\
    function,'FunctionEncrypt',\
    function,'FunctionDecrypt'
    

I wouldn't like to break any sort of standard, but which choice should I make?
Post 26 Mar 2008, 02:09
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
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revolution
Sure you can do that. It is only a pointer there are no special requirements about duplication.
Post 26 Mar 2008, 02:34
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itsnobody



Joined: 01 Feb 2008
Posts: 93
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itsnobody
yeah there's no problems with this, you can do it, make sure the export names are in alphabetical order though....having it not in alphabetical order may cause problems
Post 26 Mar 2008, 20:40
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AlexP



Joined: 14 Nov 2007
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AlexP
Yeah, but I was just wondering if it was proper to do Smile I'll probably end up having only one, and making a good note of it in the header to avoid confusion from the user. THanks!
Post 26 Mar 2008, 23:30
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asmfan



Joined: 11 Aug 2006
Posts: 392
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asmfan
Quote:

having it not in alphabetical order may cause problems

what kind of problems you encountered? May be it's just recommendation to arrange alphabetically?
Post 27 Mar 2008, 06:33
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AlexP



Joined: 14 Nov 2007
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AlexP
I highly doubt that Windows would trust every library to have their exported strings in alphabetical order, or many would have encountered those problems..
Post 27 Mar 2008, 07:30
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
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Location: In your JS exploiting you and your system
revolution
AlexP wrote:
I highly doubt that Windows would trust every library to have their exported strings in alphabetical order, or many would have encountered those problems..
The default macros in the fasm download will sort the export strings for you so that is why you don't see the problem. If you didn't use the macros and also didn't manually sort your strings then you can have problems.
Post 27 Mar 2008, 08:01
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asmfan



Joined: 11 Aug 2006
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asmfan
From MS PE & COFF documentation.
Quote:

6.3.3. Export Name Pointer Table
The export name pointer table is an array of addresses (RVAs) into the export name table. The pointers are 32 bits each and are relative to the image base. The pointers are ordered lexically to allow binary searches.
An export name is defined only if the export name pointer table contains a pointer to it.
Post 27 Mar 2008, 08:07
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revolution
When all else fails, read the source


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revolution
Hehe, if all else fails RTFM. Thanks for posting that asmfan Smile
Post 27 Mar 2008, 08:14
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asmfan



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asmfan
But notice: not a word like "must", "should" be ordered lexically... Then I can think the order only have enfluence on speed.
Post 27 Mar 2008, 08:31
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revolution
When all else fails, read the source


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revolution
asmfan wrote:
But notice: not a word like "must", "should" be ordered lexically... Then I can think the order only have enfluence on speed.
It is not possible to do a binary search on unsorted data, so it is implied that the exports must be sorted else you will be sorry.
Post 27 Mar 2008, 09:01
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asmfan



Joined: 11 Aug 2006
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asmfan
Actually I always thought Win loader searches among every entry in export table not only till the first letter of next export func. name greather lexically than the letter of nedded name.
(too lazy moment to make any tests on unsorted lists of export funcs)
Post 27 Mar 2008, 09:52
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asmfan



Joined: 11 Aug 2006
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asmfan
Just made some tests: unsorted export table works perfectly on both static linking & dynamic dll linking. Tested on Win 32-bit XP SP2+. Still no "must" word met.
Post 27 Mar 2008, 10:24
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revolution
When all else fails, read the source


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revolution
Okay, now please test with Win95 Win98, WinNT, Win2K, WinVista all versions and all patch levels. Also remember to keep testing for all future versions to be sure that MS don't screw it up some time later by deciding to enforce it due a lame "for security reasons" excuse.

Seriously, I think it would be easier to just use the macros and sort the table, then there is no need to worry about any future/past incompatibility.
Post 27 Mar 2008, 10:55
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asmfan



Joined: 11 Aug 2006
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asmfan
Some times I hate MS documentation cuz it sometimes lacks those keywords like "must" and othert. For example - lots of Native APIs take structures as parameters but nowhere you can find that the structure "must" be aligned on 4 or more and this leads to dummy mistakes. Of course we now that performance suffers because of misalignment but nowhere you meet "must". E.g. NtQueryPerformanceCounter (and its not Nt* analog) takes only 4 bytes aligned data. Of course it's natural alignment but where it's said to align data so?
Post 27 Mar 2008, 11:41
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revolution
When all else fails, read the source


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revolution
I think the reason that alignment is not mentioned in the docs is because they are aimed at HLL programmers (note all the C examples in the SDK) and they expect the HLL compiler to have nicely aligned things on the natural boundaries.
Post 27 Mar 2008, 12:14
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f0dder



Joined: 19 Feb 2004
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f0dder
asmfan: did you make a large number of exports, very scrambled, and did you import all those exports from your test exe?

Last time I checked, export-sorting was necessary on XP SP2.
Post 27 Mar 2008, 15:03
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asmfan



Joined: 11 Aug 2006
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asmfan
Nope, just imported 1 proc. which is the last in export table containing 4/5 scrambled exports in dll. A bit later I'll test it more according your advice with multiple imports from dll.
Post 27 Mar 2008, 17:22
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asmfan



Joined: 11 Aug 2006
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asmfan
Again worked fine addresses found by loader both statically and dynamically.
Post 27 Mar 2008, 18:47
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itsnobody



Joined: 01 Feb 2008
Posts: 93
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itsnobody
asmfan wrote:
Quote:

having it not in alphabetical order may cause problems

what kind of problems you encountered? May be it's just recommendation to arrange alphabetically?


A while back I was having problems with it, I was using an older version of FASM and couldn't figure out what was wrong with the DLL why some people couldn't get it to work, then I put the export names in alphabetical order and it worked

I don't know if FASM automatically does this now...
Post 27 Mar 2008, 20:52
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