getnameinfo(3)                                           getnameinfo(3)

  getnameinfo

  NAME

    getnameinfo - address-to-name translation in protocol-independent manner

  SYNOPSIS

    #include 
    #include 

    int getnameinfo(const struct sockaddr *sa, socklen_t salen, char *host,
    size_t
                    hostlen, char *serv, size_t servlen, int flags);

  DESCRIPTION

    The getnameinfo() function is defined for protocol-independent address-to-
    nodename translation. It performs functionality of gethostbyaddr(3) and
    getservbyport(3) in more sophisticated manner.

    The sa argument is a pointer to a generic socket address structure of size
    salen. The arguments host and serv are pointers to buffers to hold the
    return values. Their sizes are specified by hostlen and servlen
    respectively. Either host or serv may be NULL if the host name or service
    name is not required.

    The flags argument modifies the behavior of getnameinfo() as follows:

    If NI_NOFQDN is set, only the unqualified host name is returned for local
    fully qualified names.

    If NI_NUMERICHOST is set, then the numeric form of the host name is
    returned.

    If NI_NAMEREQD is set, then a error is returned if the host name cannot be
    looked up.

    If NI_NUMERICSERV is set, then the service is returned in numeric form.

    If NI_DGRAM is set, then the service is UDP based rather than TCP based.

  SEE ALSO

    getaddrinfo(3)

    gethostbyaddr(3)

    getservbyport(3)

    services(5)

    R. Gilligan, S. Thomson, J. Bound, and W. Stevens, "Basic Socket Interface
    Extensions for IPv6," RFC2133, April 1997.

  STANDARDS

    The getaddrinfo() function is defined IEEE POSIX 1003.1g draft
    specification, and documented in "Basic Socket Interface Extensions for
    IPv6" (RFC2133).

  USAGE NOTES

    The getnameinfo function is not thread safe.

    The getnameinfo function is not async-signal safe.