问题
We have a C# application that can join and receives data from a multicast group. This works well. We now want to support IGMPv3 and be able to specify the IP of the source when joining a multicast group. From the MSDN documentation, I don't see how to do this. I have found the following link that seems to answer my question.
http://social.msdn.microsoft.com/Forums/en/netfxnetcom/thread/e8063f6d-22f5-445e-a00c-bf46b46c1561
And here is how I implemented this:
byte[] membershipAddresses = new byte[12]; // 3 IPs * 4 bytes (IPv4)
Buffer.BlockCopy(multicastIp.GetAddressBytes(), 0, membershipAddresses, 0, 4);
Buffer.BlockCopy(sourceIp.GetAddressBytes(), 0, membershipAddresses, 4, 4);
Buffer.BlockCopy(localIp.GetAddressBytes(), 0, membershipAddresses, 8, 4);
socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, membershipAddresses);
But I get a SocketException when calling SetSocketOption() with this error: The requested address is not valid in its context
.
Can someone points me what I am doing wrong here? Thanks!
回答1:
The link states SocketOptionName.AddSourceMembership
, you are using AddMembership
.
回答2:
For enyone struggling with source multicast
static void StartListner(IPAddress sourceIp, IPAddress multicastGroupIp, IPAddress localIp, int port)
{
Task.Run(() =>
{
try
{
Console.WriteLine("Starting: " + sourceIp + " - " + multicastGroupIp + " - " + localIp + " / " + port);
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPEndPoint localEndpoint = new IPEndPoint(localIp, port);
socket.Bind(localEndpoint);
byte[] membershipAddresses = new byte[12]; // 3 IPs * 4 bytes (IPv4)
Buffer.BlockCopy(multicastGroupIp.GetAddressBytes(), 0, membershipAddresses, 0, 4);
Buffer.BlockCopy(sourceIp.GetAddressBytes(), 0, membershipAddresses, 4, 4);
Buffer.BlockCopy(localIp.GetAddressBytes(), 0, membershipAddresses, 8, 4);
socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddSourceMembership, membershipAddresses);
while (true)
{
byte[] b = new byte[1024];
int length = socket.Receive(b);
Console.WriteLine("PORT: " + port + " : " + Encoding.ASCII.GetString(b, 0, length));
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
});
}
来源:https://stackoverflow.com/questions/5145804/how-to-join-source-specific-multicast-group-in-c-sharp-igmpv3