bionic (3) ares_search.3.gz

NAME

       ares_search - Initiate a DNS query with domain search

SYNOPSIS

       #include <ares.h>

       typedef void (*ares_callback)(void *arg, int status,
       int timeouts, unsigned char *abuf, int alen)

       void ares_search(ares_channel channel, const char *name,
            int dnsclass, int type, ares_callback callback,
       void *arg)

DESCRIPTION

       The  ares_search  function  initiates a series of single-question DNS queries on the name service channel
       identified by channel, using the channel's search domains as well as a  host  alias  file  given  by  the
       HOSTALIAS environment variable.  The parameter name gives the alias name or the base of the query name as
       a NUL-terminated C string of period-separated labels; if it ends with  a  period,  the  channel's  search
       domains  will not be used.  Periods and backslashes within a label must be escaped with a backslash.  The
       parameters dnsclass and type give  the  class  and  type  of  the  query  using  the  values  defined  in
       <arpa/nameser.h>.   When  the  query  sequence  is  complete  or has failed, the ares library will invoke
       callback.  Completion or failure of the query sequence may happen immediately, or  may  happen  during  a
       later call to ares_process(3) or ares_destroy(3).

       The  callback  argument  arg  is  copied from the ares_search argument arg.  The callback argument status
       indicates whether the query sequence ended with a successful query and, if not, how  the  query  sequence
       failed.  It may have any of the following values:

       ARES_SUCCESS       A query completed successfully.

       ARES_ENODATA       No  query  completed  successfully;  when  the query was tried without a search domain
                          appended, a response was returned with no answers.

       ARES_EFORMERR      A query completed but the server claimed that the query was malformatted.

       ARES_ESERVFAIL     No query completed successfully; when the query was  tried  without  a  search  domain
                          appended, the server claimed to have experienced a failure.  (This code can only occur
                          if the ARES_FLAG_NOCHECKRESP  flag  was  specified  at  channel  initialization  time;
                          otherwise, such responses are ignored at the ares_send(3) level.)

       ARES_ENOTFOUND     No  query  completed  successfully;  when  the query was tried without a search domain
                          appended, the server reported that the queried-for domain name was not found.

       ARES_ENOTIMP       A query completed but the server does not implement the  operation  requested  by  the
                          query.   (This  code can only occur if the ARES_FLAG_NOCHECKRESP flag was specified at
                          channel initialization time; otherwise, such responses are ignored at the ares_send(3)
                          level.)

       ARES_EREFUSED      A  query  completed  but  the  server  refused  the  query.  (This code can only occur
                          returned if the ARES_FLAG_NOCHECKRESP flag was  specified  at  channel  initialization
                          time; otherwise, such responses are ignored at the ares_send(3) level.)

       ARES_TIMEOUT       No name servers responded to a query within the timeout period.

       ARES_ECONNREFUSED  No name servers could be contacted.

       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.

       If a query completed successfully, the callback argument abuf points to a result buffer of  length  alen.
       If  the query did not complete successfully, abuf will usually be NULL and alen will usually be 0, but in
       some cases an unsuccessful query result may be placed in abuf.

SEE ALSO

       ares_process(3)

AUTHOR

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

                                                  24 July 1998                                    ARES_SEARCH(3)