SCTP_PCB_FLAGS_ACCEPTING
#define SCTP_IS_LISTENING(inp) ((inp->sctp_flags & SCTP_PCB_FLAGS_ACCEPTING) != 0)
inp->sctp_flags |= SCTP_PCB_FLAGS_ACCEPTING;
inp->sctp_flags |= SCTP_PCB_FLAGS_ACCEPTING;
inp->sctp_flags &= ~SCTP_PCB_FLAGS_ACCEPTING;