Takes a service location (nodename) or a service name (servname),
    or both, and returns a pointer to a linked list of one or more
    structures of type addrinfo.
    Format
      #include  <socket.h>
      #include  <netdb.h>
      int getaddrinfo  ( const char *nodename, const char *servname,
                       const struct addrinfo *hints, struct addrinfo
                       **res );