getrpcport() - get RPC port number
int getrpcport(char *host, int prognum, int versnum, int proto)
getrpcport(3) returns the port number for version versnum of the RPC program prognum running on host and using protocol proto. It returns 0 if it cannot contact the portmapper, or if prognum is not registered. If prognum is registered but not with version versnum, it will still return a port number (for some version of the program) indicating that the program is indeed registered. The version mismatch will be detected upon the first call to the service.