4.3BSD-UWisc/man/cat3/resolver.3

RESOLVER(3)         UNIX Programmer's Manual          RESOLVER(3)



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 __r_e_s.  Most of the values have reasonable defaults and
     can be ignored. Options stored in __r_e_s._o_p_t_i_o_n_s are defined
     in _r_e_s_o_l_v._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., _r_e_s__i_n_i_t has been
          called).




Printed 12/27/86        15 November 1985                        1






RESOLVER(3)         UNIX Programmer's Manual          RESOLVER(3)



     RES_DEBUG
          Print debugging messages.

     RES_AAONLY
          Accept authoritative answers only.  _R_e_s__s_e_n_d 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.  ( _r_e_s__s_e_n_d 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.

     _R_e_s__i_n_i_t

     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.  _R_e_s__m_k_q_u_e_r_y makes a standard query
     message and places it in _b_u_f.  _R_e_s__m_k_q_u_e_r_y will return the
     size of the query or -1 if the query is larger than _b_u_f_l_e_n.
     _O_p is usually QUERY but can be any of the query types
     defined in _n_a_m_e_s_e_r._h.  _D_n_a_m_e is the domain name. If _d_n_a_m_e
     consists of a single label and the RES_DEFNAMES flag is
     enabled (the default), _d_n_a_m_e 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 vari-
     able LOCALDOMAIN.  _N_e_w_r_r is currently unused but is intended
     for making update messages.

     _R_e_s__s_e_n_d sends a query to name servers and returns an
     answer.  It will call _r_e_s__i_n_i_t 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.



Printed 12/27/86        15 November 1985                        2






RESOLVER(3)         UNIX Programmer's Manual          RESOLVER(3)



     _D_n__e_x_p_a_n_d expands the compressed domain name _c_o_m_p__d_n to a
     full domain name.  Expanded names are converted to upper
     case.  _M_s_g is a pointer to the beginning of the message,
     _e_x_p__d_n is a pointer to a buffer of size _l_e_n_g_t_h for the
     result.  The size of compressed name is returned or -1 if
     there was an error.

     _D_n__c_o_m_p compresses the domain name _e_x_p__d_n and stores it in
     _c_o_m_p__d_n.  The size of the compressed name is returned or -1
     if there were errors.  _l_e_n_g_t_h _i_s _t_h_e _s_i_z_e _o_f _t_h_e _c_o_m_p__d_n.
     _D_n_p_t_r_s is a list of pointers to previously compressed names
     in the current message.  The first pointer points to to the
     beginning of the message and the list ends with NULL.
     _l_a_s_t_d_n_p_t_r is a pointer to the end of the array pointed to
     _d_n_p_t_r_s.  A side effect is to update the list of pointers for
     labels inserted into the message by _d_n__c_o_m_p as the name is
     compressed.  If _d_n_p_t_r is NULL, we don't try to compress
     names. If _l_a_s_t_d_n_p_t_r is NULL, we don't update the list.

FILES
     /etc/resolv.conf see resolver(5)

SEE ALSO
     named(8), resolver(5), RFC882, RFC883, RFC973, RFC974,
     SMM:11 Name Server Operations Guide for BIND






























Printed 12/27/86        15 November 1985                        3