GetAdaptersInfo Function

GetAdaptersInfo Function
The GetAdaptersInfo function retrieves adapter information for the local computer.
On Windows XP and later: Use the
GetAdaptersAddresses function instead of
GetAdaptersInfo.

Syntax

DWORD GetAdaptersInfo(
  __out    PIP_ADAPTER_INFO pAdapterInfo,
  __inout  PULONG pOutBufLen
);

Parameters

pAdapterInfo [out]
A pointer to a buffer that receives a linked list of IP_ADAPTER_INFO structures.
pOutBufLen [in, out]
A pointer to a ULONG variable that specifies the size of the buffer pointed to by the pAdapterInfo parameter. If this size is insufficient to hold the adapter information, GetAdaptersInfo fills in this variable with the required size, and returns an error code of ERROR_BUFFER_OVERFLOW.

Return Value

If the function succeeds, the return value is ERROR_SUCCESS.
If the function fails, the return value is one of the following error codes.
Return code
Description
ERROR_BUFFER_OVERFLOW
The buffer to receive the adapter information is too small. This value is returned if the buffer size indicated by the pOutBufLen parameter is too small to hold the adapter information or the pAdapterInfo parameter was a NULL pointer. When this error code is returned, the pOutBufLen parameter points to the required buffer size.
ERROR_INVALID_DATA
Invalid adapter information was retrieved.
ERROR_INVALID_PARAMETER
One of the parameters is invalid. This error is returned if the pOutBufLen parameter is a NULL pointer, or the calling process does not have read/write access to the memory pointed to by pOutBufLen or the calling process does not have write access to the memory pointed to by the pAdapterInfo parameter.
ERROR_NO_DATA
No adapter information exists for the local computer.
ERROR_NOT_SUPPORTED
The GetAdaptersInfo function is not supported by the operating system running on the local computer.
Other
If the function fails, use FormatMessage to obtain the message string for the returned error.

Remarks

The GetAdaptersInfo function can retrieve information only for IPv4 addresses.
The order in which adapters appear in the list returned by this function can be controlled from the Network Connections folder: select the Advanced Settings menu item from the Advanced menu.
The GetAdaptersInfo and GetInterfaceInfo functions do not return information about the IPv4 loopback interface. Information on the loopback interface is returned by the GetIpAddrTable function.
On Windows XP and later: The list of adapters returned by
GetAdaptersInfo includes unidirectional adapters. To generate a list of adapters that can both send and receive data, call
GetUniDirectionalAdapterInfo, and exclude the returned adapters from the list returned by
GetAdaptersInfo.

Examples

This example retrieves the adapter information and prints various properties of each adapter.
Copy Code

 #include <winsock2.h>
#include <iphlpapi.h>
#include <stdio.h>
#include <stdlib.h>

#define MALLOC(x) HeapAlloc(GetProcessHeap(), 0, (x))
#define FREE(x) HeapFree(GetProcessHeap(), 0, (x))
/* Note: could also use malloc() and free() */

int __cdecl main()
{

    /* Declare and initialize variables */

// It is possible for an adapter to have multiple
// IPv4 addresses, gateways, and secondary WINS servers
// assigned to the adapter. 
//
// Note that this sample code only prints out the 
// first entry for the IP address/mask, and gateway, and
// the primary and secondary WINS server for each adapter. 

    PIP_ADAPTER_INFO pAdapterInfo;
    PIP_ADAPTER_INFO pAdapter = NULL;
    DWORD dwRetVal = 0;
    UINT i;

/* variables used to print DHCP time info */
    struct tm newtime;
    char buffer[32];
    errno_t error;

    ULONG ulOutBufLen = sizeof (IP_ADAPTER_INFO);
    pAdapterInfo = (IP_ADAPTER_INFO *) MALLOC(sizeof (IP_ADAPTER_INFO));
    if (pAdapterInfo == NULL) {
        printf("Error allocating memory needed to call GetAdaptersinfo/n");
        return 1;
    }
// Make an initial call to GetAdaptersInfo to get
// the necessary size into the ulOutBufLen variable
    if (GetAdaptersInfo(pAdapterInfo, &ulOutBufLen) == ERROR_BUFFER_OVERFLOW) {
        FREE(pAdapterInfo);
        pAdapterInfo = (IP_ADAPTER_INFO *) MALLOC(ulOutBufLen);
        if (pAdapterInfo == NULL) {
            printf("Error allocating memory needed to call GetAdaptersinfo/n");
            return 1;
        }
    }

    if ((dwRetVal = GetAdaptersInfo(pAdapterInfo, &ulOutBufLen)) == NO_ERROR) {
        pAdapter = pAdapterInfo;
        while (pAdapter) {
            printf("/tComboIndex: /t5d/n", pAdapter->ComboIndex);
            printf("/tAdapter Name: /t%s/n", pAdapter->AdapterName);
            printf("/tAdapter Desc: /t%s/n", pAdapter->Description);
            printf("/tAdapter Addr: /t");
            for (i = 0; i < pAdapter->AddressLength; i++) {
                if (i == (pAdapter->AddressLength - 1))
                    printf("%.2X/n", (int) pAdapter->Address[i]);
                else
                    printf("%.2X-", (int) pAdapter->Address[i]);
            }
            printf("/tIndex: /t%d/n", pAdapter->Index);
            printf("/tType: /t");
            switch (pAdapter->Type) {
            case MIB_IF_TYPE_OTHER:
                printf("Other/n");
                break;
            case MIB_IF_TYPE_ETHERNET:
                printf("Ethernet/n");
                break;
            case MIB_IF_TYPE_TOKENRING:
                printf("Token Ring/n");
                break;
            case MIB_IF_TYPE_FDDI:
                printf("FDDI/n");
                break;
            case MIB_IF_TYPE_PPP:
                printf("PPP/n");
                break;
            case MIB_IF_TYPE_LOOPBACK:
                printf("Lookback/n");
                break;
            case MIB_IF_TYPE_SLIP:
                printf("Slip/n");
                break;
            default:
                printf("Unknown type %ld/n", pAdapter->Type);
                break;
            }

            printf("/tIP Address: /t%s/n",
                   pAdapter->IpAddressList.IpAddress.String);
            printf("/tIP Mask: /t%s/n", pAdapter->IpAddressList.IpMask.String);

            printf("/tGateway: /t%s/n", pAdapter->GatewayList.IpAddress.String);
            printf("/t***/n");

            if (pAdapter->DhcpEnabled) {
                printf("/tDHCP Enabled: Yes/n");
                printf("/t  DHCP Server: /t%s/n",
                       pAdapter->DhcpServer.IpAddress.String);

                printf("/t  Lease Obtained: ");
                /* Display local time */
                error = _localtime32_s(&newtime, &pAdapter->LeaseObtained);
                if (error)
                    printf("Invalid Argument to _localtime32_s/n");
                else {
                    // Convert to an ASCII representation 
                    error = asctime_s(buffer, 32, &newtime);
                    if (error)
                        printf("Invalid Argument to asctime_s/n");
                    else
                        /* asctime_s returns the string terminated by /n/0 */
                        printf("%s", buffer);
                }

                printf("/t  Lease Expires:  ");
                error = _localtime32_s(&newtime, &pAdapter->LeaseExpires);
                if (error)
                    printf("Invalid Argument to _localtime32_s/n");
                else {
                    // Convert to an ASCII representation 
                    error = asctime_s(buffer, 32, &newtime);
                    if (error)
                        printf("Invalid Argument to asctime_s/n");
                    else
                        /* asctime_s returns the string terminated by /n/0 */
                        printf("%s", buffer);
                }
            } else
                printf("/tDHCP Enabled: No/n");

            if (pAdapter->HaveWins) {
                printf("/tHave Wins: Yes/n");
                printf("/t  Primary Wins Server:    %s/n",
                       pAdapter->PrimaryWinsServer.IpAddress.String);
                printf("/t  Secondary Wins Server:  %s/n",
                       pAdapter->SecondaryWinsServer.IpAddress.String);
            } else
                printf("/tHave Wins: No/n");
            pAdapter = pAdapter->Next;
            printf("/n");
        }
    } else {
        printf("GetAdaptersInfo failed with error: %d/n", dwRetVal);

    }
    if (pAdapterInfo)
        FREE(pAdapterInfo);

    return 0;
}

Requirements

Client
Requires Windows Vista, Windows XP, Windows 2000 Professional, Windows Me, or Windows 98.
Server
Requires Windows Server 2008, Windows Server 2003, or Windows 2000 Server.
Header
Declared in Iphlpapi.h.
Library
Use Iphlpapi.lib.
DLL
Requires Iphlpapi.dll.