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),

AUTHOR

       Dominick Meglio
       Copyright 2005 by Dominick Meglio.

                                            1 May 2009                        ARES_GETNAMEINFO(3)