CreateUnicastIpAddressEntry function

The CreateUnicastIpAddressEntry function adds a new unicast IP address entry on the local computer.

Syntax

NETIOAPI_API CreateUnicastIpAddressEntry(
  _In_ const MIB_UNICASTIPADDRESS_ROW *Row
);

Parameters

• Row [in]
  A pointer to a MIB_UNICASTIPADDRESS_ROW structure entry for a unicast IP address entry.

Return value

CreateUnicastIpAddressEntry returns STATUS_SUCCESS if the function succeeds.

If the function fails, CreateUnicastIpAddressEntry returns one of the following error codes:

Remarks

Use the InitializeUnicastIpAddressEntry function to initialize the members of a MIB_UNICASTIPADDRESS_ROW structure entry with default values. A driver can then change the members in the MIB_UNICASTIPADDRESS_ROW entry that it wants to modify, and then call the CreateUnicastIpAddressEntry function.

On input, your driver must initialize the following members of the MIB_UNICASTIPADDRESS_ROW structure that the Row parameter points to.

• Address
  Set to a valid unicast IPv4 or IPv6 address and family.

• InterfaceLuid or InterfaceIndex
  These members are used in the order that is listed earlier. So if InterfaceLuid is specified, this member is used to determine the interface to add the unicast IP address to. If no value was set for the InterfaceLuid member (the value of this member was set to zero), the InterfaceIndex member is next used to determine the interface.

If the OnLinkPrefixLength member of the MIB_UNICASTIPADDRESS_ROW structure that the Row parameter points to is set to 255, CreateUnicastIpAddressEntry adds the new unicast IP address with the OnLinkPrefixLength member set equal to the length of the IP address. So for a unicast IPv4 address, the OnLinkPrefixLength is set to 32 and the OnLinkPrefixLength is set to 128 for a unicast IPv6 address. If this setting would result in the incorrect subnet mask for an IPv4 address or the incorrect link prefix for an IPv6 address, the driver should set the OnLinkPrefixLength member to the correct value before calling CreateUnicastIpAddressEntry.

If a unicast IP address is created with the OnLinkPrefixLength member set incorrectly, your driver can change the IP address by calling SetUnicastIpAddressEntry with the OnLinkPrefixLength member set to the correct value.

The DadState, ScopeId, and CreationTimeStamp members of the MIB_UNICASTIPADDRESS_ROW structure that the Row parameter points to are ignored when the CreateUnicastIpAddressEntry function is called. These members are set by the network stack. The ScopeId member is automatically determined by the interface that the address is added on.

The CreateUnicastIpAddressEntry function fails if the unicast IP address that is passed in the Address member of the MIB_UNICASTIPADDRESS_ROW structure that the Row parameter points to is a duplicate of an existing unicast IP address on the interface. Note that your driver can add a loopback IP address to a loopback interface only by using the CreateUnicastIpAddressEntry function.

The unicast IP address that is passed in the Address member of the MIB_UNICASTIPADDRESS_ROW structure that the Row parameter points to is not usable immediately. The IP address is usable after the duplicate address detection process has completed successfully. It can take several seconds for the duplicate address detection process to complete because IP packets must be sent and potential responses must be waited for. For IPv6, the duplicate address detection process typically takes about 1 second. For IPv4, the duplicate address detection process typically takes about 3 seconds.

After a driver calls the CreateUnicastIpAddressEntry function, it can use the following methods to determine if an IP address is still usable:

• Use polling and the GetUnicastIpAddressEntry function
  After the call to the CreateUnicastIpAddressEntry function returns successfully, pause for 1 to 3 seconds (depending on whether an IPv6 or IPv4 address is being created) to allow time for the successful completion of the duplication address detection process. Then, call GetUnicastIpAddressEntry to retrieve the updated MIB_UNICASTIPADDRESS_ROW structure and examine the value of the DadState member. If the value of the DadState member is set to IpDadStatePreferred, the IP address is now usable. If the value of the DadState member is set to IpDadStateTentative, duplicate address detection has not yet completed. In this case, call the GetUnicastIpAddressEntry function again every 0.5 seconds while the DadState member is still set to IpDadStateTentative. If the value of the DadState member returns with some value other than IpDadStatePreferred or IpDadStateTentative, duplicate address detection has failed and the IP address is not usable.

• Call one of the IP Helper NotifyXxx notification functions to set up an asynchronous notification for when an address changes
  After the call to the CreateUnicastIpAddressEntry function returns successfully, call the NotifyUnicastIpAddressChange function to register the driver to be notified of changes to either IPv6 or IPv4 unicast IP addresses, depending on the type of IP address that is being created. When a notification is received for the IP address that is being created, call the GetUnicastIpAddressEntry function to retrieve the DadState member. If the value of the DadState member is set to IpDadStatePreferred, the IP address is now usable. If the value of the DadState member is set to IpDadStateTentative, duplicate address detection has not yet completed and the driver must wait for future notifications. If the value of the DadState member returns with some value other than IpDadStatePreferred or IpDadStateTentative, duplicate address detection has failed and the IP address is not usable.

  If, during the duplicate address detection process, the media is disconnected and then reconnected, the duplicate address detection process is restarted. So the time to complete the process might increase beyond the typical 1 second value for IPv6 or 3 second value for IPv4.

Requirements

See also

DeleteUnicastIpAddressEntry

GetUnicastIpAddressEntry

GetUnicastIpAddressTable

InitializeUnicastIpAddressEntry

MIB_UNICASTIPADDRESS_ROW

MIB_UNICASTIPADDRESS_TABLE

NL_PREFIX_ORIGIN

NL_SUFFIX_ORIGIN

NotifyIpInterfaceChange

NotifyRouteChange2

NotifyStableUnicastIpAddressTable

NotifyTeredoPortChange

NotifyUnicastIpAddressChange

SetUnicastIpAddressEntry