The UnblockSource method unblocks multicast packets originating from a specified source address so they can be received. The specified source address must have previously been blocked by a call to the BlockSource method.
The client must have completed a join to the multicast group.
The sourceAddress parameter may be either an IPv6 or IPv4 multicast address.
If the specified source address in the sourceAddress parameter was not previously blocked by a call to the BlockSource method, a SocketException is thrown with AddressNotAvailable.
If there is a socket failure while performing the unblock source operation, a SocketException is thrown. The error received is specified as a member of the SocketError enumeration.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)