NAME

       ares_getnameinfo - Address-to-nodename translation in protocol-independent manner

SYNOPSIS

       #include <ares.h>

       typedef void (*ares_nameinfo_callback)(void *arg, int status,
                                              int timeouts, char *node,
                                              char *service)

       void ares_getnameinfo(ares_channel_t *channel, const struct sockaddr *sa,
                             ares_socklen_t salen, int flags,
                             ares_nameinfo_callback callback, void *arg)

DESCRIPTION

       The  ares_getnameinfo function is defined for protocol-independent address translation. The function is a
       combination of ares_gethostbyaddr(3) and getservbyport(3). The function will translate the address either
       by executing a host query on the name service channel identified by channel or it will attempt to resolve
       it locally if possible.  The parameters sa and len give the address as a sockaddr  structure,  and  flags
       gives the options that the function will use.  Valid flags are listed below:

       ARES_NI_NOFQDN     Only the nodename portion of the FQDN is returned for local hosts.

       ARES_NI_NUMERICHOST
                          The numeric form of the hostname is returned rather than the name.

       ARES_NI_NAMEREQD   An error is returned if the hostname cannot be found in the DNS.

       ARES_NI_NUMERICSERV
                          The numeric form of the service is returned rather than the name.

       ARES_NI_TCP        The service name is to be looked up for the TCP protocol.

       ARES_NI_UDP        The service name is to be looked up for the UDP protocol.

       ARES_NI_SCTP       The service name is to be looked up for the SCTP protocol.

       ARES_NI_DCCP       The service name is to be looked up for the DCCP protocol.

       ARES_NI_NUMERICSCOPE
                          The numeric form of the scope ID is returned rather than the name.

       ARES_NI_LOOKUPHOST A hostname lookup is being requested.

       ARES_NI_LOOKUPSERVICE
                          A service name lookup is being requested.

       When  the  query is complete or has failed, the ares library will invoke callback.  Completion or failure
       of  the  query  may  happen  immediately,  or  may  happen  during  a  later  call  to   ares_process(3),
       ares_destroy(3) or ares_cancel(3).

       When  the associated callback is called, it is called with a channel lock so care must be taken to ensure
       any processing is minimal to prevent DNS channel stalls.

       The callback may be triggered from a different thread than the one which called ares_getnameinfo(3).

       For integrators running their own event loops and not using ARES_OPT_EVENT_THREAD, care needs to be taken
       to ensure any file descriptor lists are updated immediately within the eventloop when notified.

       The callback argument arg is copied from the ares_getnameinfo argument arg.  The callback argument status
       indicates whether the query succeeded and, if not, how it failed.  It  may  have  any  of  the  following
       values:

       ARES_SUCCESS       The host lookup completed successfully.

       ARES_ENOTIMP       The ares library does not know how to look up addresses of type family.

       ARES_ENOTFOUND     The address addr was not found.

       ARES_ENOMEM        Memory was exhausted.

       ARES_ECANCELLED    The query was cancelled.

       ARES_EDESTRUCTION  The name service channel channel is being destroyed; the query will not be completed.

       ARES_EBADFLAGS     The flags parameter contains an illegal value.

       The callback argument timeouts reports how many times a query timed out during the execution of the given
       request.

       On  successful  completion  of  the  query, the callback argument node contains a string representing the
       hostname  (assuming  ARES_NI_LOOKUPHOST  was  specified).  Additionally,  service   contains   a   string
       representing  the  service  name  (assuming  ARES_NI_LOOKUPSERVICE  was specified).  If the query did not
       complete successfully, or one of the values was not requested, node or service will be NULL.

SEE ALSO

       ares_process(3),

                                                   1 May 2009                                ARES_GETNAMEINFO(3)