使用路由Hold-Down状态

以下示例代码演示如何将目标标记为保持状态，以及如何创建包含处于保持状态的路由的目标枚举。

#include <windows.h>

// Macro to allocate a RTM_DEST_INFO on the stack
#define ALLOC_RTM_DEST_INFO(NumViews, NumInfos)
        (PRTM_DEST_INFO) _alloca(RTM_SIZE_OF_DEST_INFO(NumViews) * NumInfos)

void main()
{

// Mark the destination for hold down in Unicast view

Status = RtmHoldDestination(RtmRegHandle,
                            DestHandle,
                            RTM_VIEW_MASK_UCAST,
                            30*1000); // 30 seconds
// Check Status

// When the last route on this destination is deleted,
// it is moved from the ViewInfo's Route to HoldRoute.

// To enumerate all destinations - even the ones with
// just hold down routes, use the following API calls

// Code to enumerate destinations in the table

MaxHandles = RegnProfile.MaxHandlesInEnum;

DestInfos = ALLOC_RTM_DEST_INFO(NumViews, MaxHandles);

DestInfoSize = RTM_SIZE_OF_DEST_INFO(NumViews);

// Enumerate all destinations in the subtree (0 / 0)
// (basically the whole tree; you can
// also achieve this by using RTM_ENUM_START)

RTM_IPV4_MAKE_NET_ADDRESS(&NetAddress,
                          0x00000000,
                          0);

// Create a destination enumeration in views = RTM_VIEW_MASK_ANY.

Status = RtmCreateDestEnum(RtmRegHandle,
                           RTM_VIEW_MASK_ANY, // MUST BE EXACTLY THE SAME AS THIS
                           RTM_ENUM_RANGE,
                           &NetAddress,
                           RTM_BEST_PROTOCOL, // Get best route on each destination
                           &EnumHandle);

if (Status == NO_ERROR)
{
    do
    {
        NumInfos = MaxHandles;

        Status = RtmGetEnumDests(RtmRegHandle
                                 EnumHandle,
                                 &NumInfos,
                                 DestInfos);

        for (i = 0; i < NumInfos; i++)
        {
            DestInfo = (PRTM_DEST_INFO) ((PUCHAR)DestInfos+(i*DestInfoSize));

            // Process the current destination information
            // As RTM_VIEW_MASK_ANY = 0, we have
            // no view information returned in the call
            
            // Get actual DestInfo in the specified views 
            // (Assume that only unicast is specified)
                        
            Status = RtmGetDestInfo(RtmRegHandle,
                                    DestInfo.DestHandle,
                                    RTM_BEST_PROTOCOL,
                                    RTM_VIEW_MASK_UCAST,
                                    &DestInfoActual);

            if (Status == NO_ERROR)
            {
                HoldRoute = DestInfoActual.ViewInfo[0].HoldRoute;
                BestRoute = DestInfoActual.ViewInfo[0].Route;

                // Advertise best unicast route (or the hold down route)

                if (HoldRoute)
                {
                    // HoldRoute exists; Advertise it if hold down protocol
                    ; 
                }

                RtmReleaseDestInfo(RtmRegHandle, &DestInfoActual);
            }

            ...
        }

        RtmReleaseDests(RtmRegHandle, NumInfos, DestInfos);
    }
    while (Status == NO_ERROR)

    // Close the enumeration and release its resources
    RtmDeleteEnumHandle(RtmRegHandle, EnumHandle);
}