Question

In the command prompt I could use:

netsh int tcp set global congestionprovider=ctcp

I’m wondering if there is a way I could accomplish the same thing programically in C/C++ without using system().

I’m assuming i’m probably going to have to use COM?

EDIT: Also information about how I could access other information that I would normally access through netsh in C/C++, would be nice 🙂 (Example: netsh int tcp show global)

Answer 1

Reading between the lines, this might be achievable using a manual registry modification in the same way described for the Windows XP/Windows Server 2003 backport of CTCP. Hypothetically, you would have to set the given value to 1 using RegSetValueEx and inspect it using RegQueryValueEx to see what is the state at this time.

When you apply this hotfix, the following registry subkey is created: 
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
The properties of this subkey are as follows: 
Name: TCPCongestionControl
Type: REG_DWORD
Value: 1
When the value is set to 1, CTCP support is enabled. When the value is set to 0, CTCP support is disabled.

Whether this works for you at all, or without a reboot or not depends on 1) whether the appropriate component auto-detects registry mods and 2) whether that’s all there is to it on the newer OSes. Does not seem like this would be too hard to try out, though.