[System] Fix MacOsNetworkInterface.ImplGetAllNetworkInterfaces()

On my (cursed?) MacBook Pro, calling
System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces()
results in an exception:

	System.ArgumentException: length
		at System.Array.Copy (System.Array sourceArray, Int32 sourceIndex, System.Array destinationArray, Int32 destinationIndex, Int32 length) [0x00000] in <filename unknown>:0
		at System.Net.NetworkInformation.MacOsNetworkInterface.ImplGetAllNetworkInterfaces () [0x00000] in <filename unknown>:0
		at System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces () [0x00000] in <filename unknown>:0

Some printfs later, and we see why:

	Array.Copy(array.Length=12, 3, array.Length=0, 0, 0)
	Array.Copy(array.Length=12, 4, array.Length=0, 0, 0)
	Array.Copy(array.Length=12, 4, array.Length=0, 0, 0)
	Array.Copy(array.Length=12, 3, array.Length=6, 0, 6)
	Array.Copy(array.Length=12, 3, array.Length=6, 0, 6)
	Array.Copy(array.Length=12, 3, array.Length=8, 0, 4)
	Array.Copy(array.Length=12, 4, array.Length=6, 0, 6)
	Array.Copy(array.Length=12, 8, array.Length=6, 0, 6)
	# BOOM!

(Apparently I have 8 interfaces: lo0, gif0, stf0, en0, en1, fw0, p2p0,
and vboxnet0.)

The problem is readily obvious: we're trying to read 6 bytes of data
when only 4 are available, and Array.Copy() complains appropriately.

The fix -- which looks to almost contradict a02076ba -- is to use
`sockaddrdl.sdl_data.Length - sockaddrdl.sdl_nlen` instead of
`sockaddrdl.sdl_data.Length - macAddress.Length` (or sdl_alen).
sdl_nlen is the offset into the source sockaddrdl.sdl_data array, and
in this case sockaddrdl.sdl_alen (the length of the destination
macAddress) isn't the same as sockaddrdl.sdl_nlen, hence the breakage.

diff --git a/mcs/class/System/System.Net.NetworkInformation/NetworkInterface.cs b/mcs/class/System/System.Net.NetworkInformation/NetworkInterface.cs
index 92d2e42df66f147255fa82f4d70c0a781d7687f2..9ff82f5ca6ac6b8eb62ce8a3889c901e5b69252d 100644 (file)
--- a/mcs/class/System/System.Net.NetworkInformation/NetworkInterface.cs
+++ b/mcs/class/System/System.Net.NetworkInformation/NetworkInterface.cs
@@ -468,7 +468,7 @@ namespace System.Net.NetworkInformation {
                                                        MacOsStructs.sockaddr_dl sockaddrdl = (MacOsStructs.sockaddr_dl) Marshal.PtrToStructure (addr.ifa_addr, typeof (MacOsStructs.sockaddr_dl));
 
                                                        macAddress = new byte [(int) sockaddrdl.sdl_alen];
-                                                       Array.Copy (sockaddrdl.sdl_data, sockaddrdl.sdl_nlen, macAddress, 0, Math.Min (macAddress.Length, sockaddrdl.sdl_data.Length - macAddress.Length));
+                                                       Array.Copy (sockaddrdl.sdl_data, sockaddrdl.sdl_nlen, macAddress, 0, Math.Min (macAddress.Length, sockaddrdl.sdl_data.Length - sockaddrdl.sdl_nlen));
                                                        index = sockaddrdl.sdl_index;
 
                                                        int hwtype = (int) sockaddrdl.sdl_type;