GetAdaptersInfo function - Windows IP Helper API

GetAdaptersInfo

Retrieves adapter information for the local computer. This function is superseded by GetAdaptersAddresses, but it remains supported for compatibility.

Syntax

DWORD GetAdaptersInfo(
  PIP_ADAPTER_INFO pAdapterInfo,
  PULONG           pOutBufLen
);

Parameters

Parameter	Type	Description
pAdapterInfo	PIP_ADAPTER_INFO	Pointer to a buffer that receives an array of `IP_ADAPTER_INFO` structures. If the function fails because the buffer is too small, this parameter is ignored.
pOutBufLen	PULONG	On input, the size of the buffer pointed to by `pAdapterInfo`, in bytes. On output, receives the required size when the buffer is insufficient.

Return Value

The function returns ERROR_SUCCESS (0) if the call succeeds. On failure it returns a Windows error code, such as ERROR_BUFFER_OVERFLOW (111) when the supplied buffer is too small.

Remarks

The IP_ADAPTER_INFO structure contains fields like AdapterName, Description, IpAddressList, and GatewayList.
To retrieve the full list, first call the function with pAdapterInfo set to NULL to obtain the required buffer size.
For IPv6 and more detailed information, use GetAdaptersAddresses.

Example

#include <windows.h>
#include <iphlpapi.h>
#pragma comment(lib, "iphlpapi.lib")

int main() {
    ULONG buflen = 0;
    GetAdaptersInfo(NULL, &buflen); // Get required size

    PIP_ADAPTER_INFO adapter = (PIP_ADAPTER_INFO)malloc(buflen);
    if (adapter == NULL) return 1;

    DWORD rc = GetAdaptersInfo(adapter, &buflen);
    if (rc == ERROR_SUCCESS) {
        PIP_ADAPTER_INFO cur = adapter;
        while (cur) {
            wprintf(L"Adapter: %S\n", cur->Description);
            wprintf(L"IP Address: %s\n", cur->IpAddressList.IpAddress.String);
            cur = cur->Next;
        }
    }
    free(adapter);
    return 0;
}

Microsoft Docs