NAME

       ares_gethostbyname - Initiate a host query by name

SYNOPSIS

       #include <ares.h>

       typedef void (*ares_host_callback)(void *arg, int status,
       int timeouts, struct hostent *hostent)

       void ares_gethostbyname(ares_channel channel, const char *name,
            int family, ares_host_callback callback, void *arg)

DESCRIPTION

       The ares_gethostbyname function initiates a host query by name on the name service channel
       identified by channel.  The parameter name  gives  the  hostname  as  a  NUL-terminated  C
       string,  and  family gives the desired type of address for the resulting host entry.  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).

       The callback argument arg  is  copied  from  the  ares_gethostbyname  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 find addresses of type family.

       ARES_EBADNAME      The hostname name is composed entirely of numbers and periods,  but  is
                          not a valid representation of an Internet address.

       ARES_ENODATA       There was no data returned to extract a result from.

       ARES_ENOTFOUND     The name name 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.

       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 hostent points to a struct
       hostent containing the name of the host returned by the query.  The callback need not  and
       should not attempt to free the memory pointed to by hostent; the ares library will free it
       when the callback returns.  If the query did not complete successfully,  hostent  will  be
       NULL.

SEE ALSO

       ares_process(3), ares_gethostbyaddr(3)

AUTHOR

       Greg Hudson, MIT Information Systems
       Copyright 1998 by the Massachusetts Institute of Technology.

                                           25 July 1998                     ARES_GETHOSTBYNAME(3)