ares_mkquery.txt

RTL-lwIP is the porting of the lwIP TCP/IP stack to RTLinux-GPL.The focus of the RTL-lwIP stack is

ARES_MKQUERY(3)                                                ARES_MKQUERY(3)



NAME
       ares_mkquery - Compose a single-question DNS query buffer

SYNOPSIS
       #include <ares.h>

       int ares_mkquery(const char *name, int dnsclass, int type,
            unsigned short id, int rd, char **buf,
            int *buflen)

DESCRIPTION
       The  ares_mkquery function composes a DNS query with a single question.
       The parameter name gives the query name as a NUL-terminated C string of
       period-separated  labels  optionally  ending with a period; periods and
       backslashes within a label must be escaped with a backlash.  The param-
       eters  dnsclass and type give the class and type of the query using the
       values defined in <arpa/nameser.h>.  The parameter id  gives  a  16-bit
       identifier for the query.  The parameter rd should be nonzero if recur-
       sion is desired, zero if not.  The query will be placed in an allocated
       buffer, a pointer to which will be stored in the variable pointed to by
       buf, and the length of which will be stored in the variable pointed  to
       by buflen.  It is the caller's responsibility to free this buffer using
       ares_free_string when it is no longer needed.

RETURN VALUES
       ares_mkquery can return any of the following values:

       ARES_SUCCESS   Construction of the DNS query succeeded.

       ARES_EBADNAME  The query name name could not be  encoded  as  a  domain
                      name, either because it contained a zero-length label or
                      because it contained a label of more than 63 characters.

       ARES_ENOMEM    Memory was exhausted.

SEE ALSO
       ares_expand_name(3), ares_free_string(3)

AUTHOR
       Greg Hudson, MIT Information Systems
       Copyright 1998, 2000 by the Massachusetts Institute of Technology.



                                4 January 2000                 ARES_MKQUERY(3)