Question

I used two sockets in the same process, one acting as multicast server and the other acting as multicast client. I am trying to combine both server and client functionality in a single socket. Could not succeed till now. Did any one tried making a single socket as multicast server and client. Is it possible? If not any reference that states the limitation would be appreciated. Thank a lot.

Answer 1

It is possible, at least on windows. Try following example(without error checking):

SOCKET the_socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

sockaddr_in service;
service.sin_family = AF_INET;
service.sin_addr.s_addr = inet_addr("192.168.1.117");
service.sin_port = htons(56565);

int ret = bind(the_socket, (SOCKADDR *) &service, sizeof (service));

unsigned int grpaddr = inet_addr("224.4.4.44");
unsigned int iaddr = inet_addr("192.168.1.117");

//You should have the equivalent function in your existing client 
//to join the multicast group
ret = join_source_group(the_socket, grpaddr, service.sin_addr.s_addr, iaddr);

std::string data = "AA";

sockaddr_in group;
group.sin_family = AF_INET;
group.sin_addr.s_addr = inet_addr("224.4.4.44");
group.sin_port = htons(56565);

ret = sendto(the_socket, data.c_str(), data.length(), 0, (const sockaddr*)&group, sizeof(group));

char recvdata[3] = {0};
ret = recv(the_socket, recvdata, 3, 0);

leave_source_group(the_socket, grpaddr, service.sin_addr.s_addr, iaddr);