resolver(3N)                                         resolver(3N)



NAME
     res_mkquery, res_send, res_init, dn_comp, dn_expand -
     resolver routines

SYNOPSIS
     #include <sys/types.h>
     #include <netinet/in.h>
     #include <arpa/nameser.h>
     #include <resolv.h>

     res_mkquery(op, dname, class, type, data, datalen, newrr,
     buf, buflen)
     int op;
     char *dname;
     int class, type;
     char *data;
     int datalen;
     struct rrec *newrr;
     char *buf;
     int buflen;

     res_send(msg, msglen, answer, anslen)
     char *msg;
     int msglen;
     char *answer;
     int anslen;

     res_init()

     dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr)
     char *exp_dn, *comp_dn;
     int length;
     char **dnptrs, **lastdnptr;

     dn_expand(msg, eomorig, comp_dn, exp_dn, length)
     char *msg, *eomorig, *comp_dn, exp_dn;
     int length;

DESCRIPTION
     These routines are used for making, sending and interpreting
     packets to Internet domain name servers. Global information
     that is used by the resolver routines is kept in the vari-
     able _res.  Most of the values have reasonable defaults and
     can be ignored. Options stored in _res.options are defined
     in resolv.h and are as follows. Options are a simple bit
     mask and are or'ed in to enable.

     RES_INIT
          True if the initial name server address and default
          domain name are initialized (i.e., res_init has been
          called).




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resolver(3N)                                         resolver(3N)



     RES_DEBUG
          Print debugging messages.

     RES_AAONLY
          Accept authoritative answers only.  Res_send will con-
          tinue until it finds an authoritative answer or finds
          an error.  Currently this is not implemented.

     RES_USEVC
          Use TCP connections for queries instead of UDP.

     RES_STAYOPEN
          Used with RES_USEVC to keep the TCP connection open
          between queries.  This is useful only in programs that
          regularly do many queries.  UDP should be the normal
          mode used.

     RES_IGNTC
          Unused currently (ignore truncation errors, i.e., don't
          retry with TCP).

     RES_RECURSE
          Set the recursion desired bit in queries. This is the
          default.  (res_send does not do iterative queries and
          expects the name server to handle recursion.)

     RES_DEFNAMES
          Append the default domain name to single label queries.
          This is the default.

     Res_init reads the initialization file to get the default
     domain name and the Internet address of the initial hosts
     running the name server. If this line does not exist, the
     host running the resolver is tried.

     Res_mkquery makes a standard query message and places it in
     buf.  Res_mkquery will return the size of the query or -1 if
     the query is larger than buflen.  Op is usually QUERY but
     can be any of the query types defined in nameser.h.  Dname
     is the domain name. If dname consists of a single label and
     the RES_DEFNAMES flag is enabled (the default), dname will
     be appended with the current domain name. The current domain
     name is defined in a system file and can be overridden by
     the environment variable LOCALDOMAIN.  Newrr is currently
     unused but is intended for making update messages.

     Res_send sends a query to name servers and returns an
     answer.  It will call res_init if RES_INIT is not set, send
     the query to the local name server, and handle timeouts and
     retries. The length of the message is returned or -1 if
     there were errors.




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resolver(3N)                                         resolver(3N)



     Dn_expand expands the compressed domain name comp_dn to a
     full domain name.  Expanded names are converted to upper
     case.  Msg is a pointer to the beginning of the message,
     exp_dn is a pointer to a buffer of size length for the
     result.  The size of compressed name is returned or -1 if
     there was an error.

     Dn_comp compresses the domain name exp_dn and stores it in
     comp_dn.  The size of the compressed name is returned or -1
     if there were errors.  Length is the size of the array
     pointed to by comp_dn.  Dnptrs is a list of pointers to pre-
     viously compressed names in the current message.  The first
     pointer points to to the beginning of the message and the
     list ends with NULL.  Lastdnptr is a pointer to the end of
     the array pointed to dnptrs.  A side effect is to update the
     list of pointers for labels inserted into the message by
     dn_comp as the name is compressed.  If dnptr is NULL, we
     don't try to compress names. If lastdnptr is NULL, we don't
     update the list.

NOTE
     These functions are defined in the 88open Binary and Object
     Compatibility Standards' Networking Supplements (BCSNS and
     OCSNS) for use in BCSNS/OCSNS compliant applications.
     OCSNS-defined functions may be accessed by passing OCS
     options to cc(1) and ld(1).

FILES
     /etc/resolv.conf

SEE ALSO
     named(1M), resolver(4C), RFC882, RFC883, RFC973, RFC974,
     The Name Server in the CX/UX Networking Reference Manual.






















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