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How to set subnet mask using Windows API function?

Posted on 2013-10-23
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Last Modified: 2013-10-29
I want to set subnet mask for Windows (.eg: 255.255.255.0). Which Windows API functions is suitable for this?

I try using CreateUnicastIpAddressEntry(&ipRow) with the parameter ipRow. OnLinkPrefixLength that content size of subnet to set (prefixlength get based on calling ConvertIpv4MaskToLength(&mask, maskLength)). However, there is two problems:
1.    the input parameter mask is kind of integer I don’t know how to set it from “255.255.255.0”.

2. I try setting mask with value 16777215 and ConvertIpv4MaskToLength(&mask, maskLength) return error “Access violation writing location 0x00000000” related memory area of parameter maskLength.

Regards.
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Question by:FSOFT-SA
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jkr earned 500 total points
ID: 39594342
As for 1: To convert a string netmask or IP address to it's integer equivalent, use 'inet_addr()' (http://msdn.microsoft.com/en-us/library/windows/desktop/ms738563(v=vs.85).aspx), e.g.

ULONG ulMask = inet_addr("255.255.255.0");

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As for 2: Can you post your code for that call?  This should be something like

UINT8 MaskLength;
ULONG ulMask = inet_addr("255.255.255.0");

ConvertIpv4MaskToLength(ulMask,&MaskLength); // use the address of an UINT8 here, not an PUINT8!

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I assume the latter (using a pointer instead the address of a variable) was/is the issue here.
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