ISC_EVENTCLASS_SOCKET
#define ISC_SOCKEVENT_RECVDONE (ISC_EVENTCLASS_SOCKET + 1)
#define ISC_SOCKEVENT_SENDDONE (ISC_EVENTCLASS_SOCKET + 2)
#define ISC_SOCKEVENT_NEWCONN (ISC_EVENTCLASS_SOCKET + 3)
#define ISC_SOCKEVENT_CONNECT (ISC_EVENTCLASS_SOCKET + 4)
#define ISC_SOCKEVENT_INTR (ISC_EVENTCLASS_SOCKET + 256)
#define ISC_SOCKEVENT_INTW (ISC_EVENTCLASS_SOCKET + 257)