NotifyIpInterfaceChange function (netioapi.h) does not notify on manual DNS changes

Question

NotifyIpInterfaceChange function (netioapi.h) does not notify on manual DNS changes

Brad House 0

I work on the c-ares open source asynchronous DNS library (https://c-ares.org) and we have recently added automatic configuration reloading when we detect a network configuration change has occurred.

We get notifications properly when network interfaces go up or down, or IP addresses change (e.g. DHCP), but we aren't getting notifications for a user manually changing a DNS server via Control Panel -> Network and Internet -> Network Connections, then right click on an interface and go to properties then modify the DNS server in "Internet Protocol Version 4 (TCP/IPv4)" or "Internet Protocol Version 6 (TCP/IPv6)".

We used NotifyIpInterfaceChange() for this (https://learn.microsoft.com/en-us/windows/win32/api/netioapi/nf-netioapi-notifyipinterfacechange), which the documentation seems to indicate since we made a change to the interface we should be notified, however no notification is sent. We would expect to get a MibParameterNotification.

We also tried using NotifyUnicastIpAddressChange() but that didn't notify on that condition either.

This was tested on an up-to-date Windows 11 development machine. I would consider this a bug in NotifyIpInterfaceChange() since it doesn't match the description in the documentation.

Xiaopo Yang - MSFT 12,731 Reputation points Microsoft External Staff

2024-06-06T01:45:33.71+00:00
There is no NotifyIpInterfaceChange identifier when I include the Iphlpapi.h header. Update: reproduced with the following code in a Windows desktop application. Exactly to say, I cannot make the callback triggered including changing a DNS server via Control Panel -> Network and Internet -> Network Connections.

#include <ws2tcpip.h> #include <iphlpapi.h> VOID (NETIOAPI_API_ MyCallback) ( _In_ PVOID CallerContext, _In_ PMIB_IPINTERFACE_ROW Row OPTIONAL, _In_ MIB_NOTIFICATION_TYPE NotificationType ) { } HANDLE h{}; DWORD d = NotifyIpInterfaceChange(AF_UNSPEC, MyCallback, NULL, FALSE, &h);
Brad House 0 Reputation points

2024-06-09T15:12:02.22+00:00

Glad you were able to confirm my findings. Where do we go from here?
Gary Nebbett 6,216 Reputation points

2024-06-09T17:51:09.61+00:00

Hello Brad,

The documentation is not specific about exactly which type of events/changes trigger a notification. A quick look at the behaviour and binary code suggests that the notifications relate to the kernel-mode aspects of network interfaces. The name server settings are a purely user-mode concern.

I traced the user-mode behaviour and there does not seem to be any general notification feature. One can see that dnsapi!Reg_SetValuePropertyAndAlertCache calls dnsapi!DnsNotifyResolverEx, but this notification is just an RPC to the Dnscache service.

What one could do is to use a routine like RegNotifyChangeKeyValue to monitor the HKLM\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\Interfaces and HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces keys.

Gary
Brad House 0 Reputation points

2024-06-11T18:33:03.72+00:00

@Gary Nebbett Thanks for the hint regarding RegNotifyChangeKeyValue, I'll look into that and see if I can use that. We're currently using GetAdaptersAddresses() to retrieve the DNS server configuration but if that is really pulling in some data stored in the registry then that sounds like a viable workaround.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.

Gary Nebbett 6,216

Hello Brad,

This is the list of reasons that I think trigger a NotifyIpInterfaceChange callback:

<valueMap name="IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap">
  <map value="0" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.InterfaceAddition)" />
  <map value="1" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.InterfaceDeletion)" />
  <map value="2" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.ZoneChange)" />
  <map value="3" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.ConfigurationFlagChange)" />
  <map value="4" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.ForwardingEnable)" />
  <map value="5" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.ForwardingDisable)" />
  <map value="6" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.WeakHostReceiveEnable)" />
  <map value="7" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.WeakHostReceiveDisable)" />
  <map value="8" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.NetworkCategoryStateChange)" />
  <map value="9" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.MetricChange)" />
  <map value="10" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.MediaConnect)" />
  <map value="11" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.MediaDisconnect)" />
  <map value="12" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.OffloadCapabilityChange)" />
  <map value="13" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.DisableDefaultRoutesSet)" />
  <map value="14" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.DisableDefaultRoutesReset)" />
  <map value="15" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.ForceTunnelingSet)" />
  <map value="16" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.ForceTunnelingReset)" />
  <map value="17" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.LimitedLinkConnectivitySet)" />
  <map value="18" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.LimitedLinkConnectivityReset)" />
  <map value="19" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.LocalityConfigChange)" />
  <map value="20" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.RoutingFlagsSet)" />
  <map value="21" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.RoutingFlagsReset)" />
  <map value="22" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.PortStateChange)" />
  <map value="23" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.RscUnawareIpsnpiClientPresent)" />
  <map value="24" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.RscUnawareIpsnpiClientAbsent)" />
  <map value="25" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.PromiscuousModeEnabled)" />
  <map value="26" message="$(string.valueMap.IP_INTERFACE_CHANGE_NOTIFY_REASON_ValueMap.PromiscuousModeDisabled)" />
</valueMap>

Gary

1 answer

Your answer

Xiaopo Yang - MSFT 12,731 Reputation points Microsoft External Staff

2024-06-06T01:45:33.71+00:00

There is no NotifyIpInterfaceChange identifier when I include the Iphlpapi.h header. Update: reproduced with the following code in a Windows desktop application. Exactly to say, I cannot make the callback triggered including changing a DNS server via Control Panel -> Network and Internet -> Network Connections.

#include <ws2tcpip.h> #include <iphlpapi.h> VOID (NETIOAPI_API_ MyCallback) ( _In_ PVOID CallerContext, _In_ PMIB_IPINTERFACE_ROW Row OPTIONAL, _In_ MIB_NOTIFICATION_TYPE NotificationType ) { } HANDLE h{}; DWORD d = NotifyIpInterfaceChange(AF_UNSPEC, MyCallback, NULL, FALSE, &h);
Brad House 0 Reputation points

2024-06-09T15:12:02.22+00:00

Glad you were able to confirm my findings. Where do we go from here?
Gary Nebbett 6,216 Reputation points

2024-06-09T17:51:09.61+00:00

Hello Brad,

The documentation is not specific about exactly which type of events/changes trigger a notification. A quick look at the behaviour and binary code suggests that the notifications relate to the kernel-mode aspects of network interfaces. The name server settings are a purely user-mode concern.

I traced the user-mode behaviour and there does not seem to be any general notification feature. One can see that dnsapi!Reg_SetValuePropertyAndAlertCache calls dnsapi!DnsNotifyResolverEx, but this notification is just an RPC to the Dnscache service.

What one could do is to use a routine like RegNotifyChangeKeyValue to monitor the HKLM\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\Interfaces and HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces keys.

Gary
Brad House 0 Reputation points

2024-06-11T18:33:03.72+00:00

@Gary Nebbett Thanks for the hint regarding RegNotifyChangeKeyValue, I'll look into that and see if I can use that. We're currently using GetAdaptersAddresses() to retrieve the DNS server configuration but if that is really pulling in some data stored in the registry then that sounds like a viable workaround.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.

Answer 1

Xiaopo Yang - MSFT 12,731 Microsoft External Staff

Hello @Brad House,

Where do we go from here?

If the issue has a big impact on you, you can open a Windows SDK incident at https://developer.microsoft.com/en-us/windows/support/?tabs=Contact-us so that our engineer can work with you closely and please choose the 'Networking Development - Internet Protocol Helper (IP Helper) API' for this issue. In-addition, if the support engineer determines that the issue is the result of a bug the service request will be a no-charge case and you won't be charged.

Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.

Share via

NotifyIpInterfaceChange function (netioapi.h) does not notify on manual DNS changes

1 answer

Your answer