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Bug 41897 - NotSupportedException thrown from IPInterfaceProperties.UnicastAddresses
Summary: NotSupportedException thrown from IPInterfaceProperties.UnicastAddresses
Alias: None
Product: Class Libraries
Classification: Mono
Component: System (show other bugs)
Version: master
Hardware: PC Windows
: --- normal
Target Milestone: Untriaged
Assignee: Marek Safar
Depends on:
Reported: 2016-06-16 14:04 UTC by Mike Voorhees
Modified: 2016-06-21 14:04 UTC (History)
2 users (show)

See Also:
Is this bug a regression?: ---
Last known good build:


Description Mike Voorhees 2016-06-16 14:04:55 UTC
Test Case :

foreach (var localAdapter in NetworkInterface.GetAllNetworkInterfaces())
	var ipProperties = localAdapter.GetIPProperties();
	foreach (var localAddress in ipProperties.UnicastAddresses)

Console.WriteLine("All Good!");

Results in exception :

Unhandled Exception:
System.NotSupportedException: The collection is read-only.
  at System.Net.NetworkInformation.UnicastIPAddressInformationCollection.Add (System.Net.NetworkInformation.UnicastIPAddressInformation address) <0x2aa5018 + 0x00037> in <filename unknown>:0
  at System.Net.NetworkInformation.Win32IPInterfaceProperties2.Win32FromUnicast (System.Int32 ifIndex, System.IntPtr ptr) <0x2aa4c20 + 0x0013e> in <filename unknown>:0
  at System.Net.NetworkInformation.Win32IPInterfaceProperties2.get_UnicastAddresses () <0x2aa4388 + 0x00073> in <filename unknown>:0
  at DateTimeProblem.Program.Main (System.String[] args) <0x2aa11a8 + 0x00050> in <filename unknown>:0
[ERROR] FATAL UNHANDLED EXCEPTION: Nested exception trying to figure out what went wrong


UnicastIPAddressInformationCollection is coming from reference source now, while Win32IPInterfaceProperties2 is a mono implementation.  Looks like the assumption made by the following code that it can call Add on UnicastIPAddressInformationCollection is no longer true.

private static UnicastIPAddressInformationCollection Win32FromUnicast(int ifIndex, IntPtr ptr)
	UnicastIPAddressInformationCollection unicastIPAddressInformationCollection = new UnicastIPAddressInformationCollection();
	IntPtr intPtr = ptr;
	while (intPtr != IntPtr.Zero)
		unicastIPAddressInformationCollection.Add(new Win32UnicastIPAddressInformation(ifIndex, info));
		intPtr = info.Next;
	return unicastIPAddressInformationCollection;
Comment 1 Marek Safar 2016-06-21 14:04:07 UTC
Fixed in master and Mono 4.5.1

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