Flag Bits for WSASocket

In some instances sockets joined to a multipoint session may have some differences in behavior from point-to-point sockets. For example, a d_leaf socket in a rooted data plane scheme can only send information to the d_root participant. This creates a need for the application to be able to indicate the intended use of a socket coincident with its creation. This is done through four-flag bits that can be set in the dwFlags parameter to WSASocket:

• WSA_FLAG_MULTIPOINT_C_ROOT, for the creation of a socket acting as a c_root, and only allowed if a rooted control plane is indicated in the corresponding WSAPROTOCOL_INFO entry.
• WSA_FLAG_MULTIPOINT_C_LEAF, for the creation of a socket acting as a c_leaf, and only allowed if XP1_SUPPORT_MULTIPOINT is indicated in the corresponding WSAPROTOCOL_INFO entry.
• WSA_FLAG_MULTIPOINT_D_ROOT, for the creation of a socket acting as a d_root, and only allowed if a rooted data plane is indicated in the corresponding WSAPROTOCOL_INFO entry.
• WSA_FLAG_MULTIPOINT_D_LEAF, for the creation of a socket acting as a d_leaf, and only allowed if XP1_SUPPORT_MULTIPOINT is indicated in the corresponding WSAPROTOCOL_INFO entry.

Note that when creating a multipoint socket, exactly one of the two control-plane flags, and one of the two data-plane flags must be set in WSASocket's dwFlags parameter. Thus, the four possibilities for creating multipoint sockets are:

• "c_root/d_root"
• "c_root/d_leaf"
• "c_leaf/d_root"
• "c_leaf /d_leaf"