4ef23ce695
package does have BXA export approval, but the licensing strings on the dnssafe code are a bit unpleasant. The crypto is easy to restore and bind will run without it - just without full dnssec support. Obtained from: The Internet Software Consortium (www.isc.org)
582 lines
16 KiB
Groff
582 lines
16 KiB
Groff
.\" Copyright (c) 1985, 1995 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms are permitted provided
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.\" that: (1) source distributions retain this entire copyright notice and
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.\" comment, and (2) distributions including binaries display the following
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.\" acknowledgement: ``This product includes software developed by the
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.\" University of California, Berkeley and its contributors'' in the
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.\" documentation or other materials provided with the distribution and in
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.\" all advertising materials mentioning features or use of this software.
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.\" Neither the name of the University nor the names of its contributors may
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.\" be used to endorse or promote products derived from this software without
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.\" specific prior written permission.
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.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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.\"
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.\" @(#)resolver.3 6.5 (Berkeley) 6/23/90
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.\" $Id: resolver.3,v 8.11 1999/09/13 23:33:24 vixie Exp $
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.\"
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.Dd October 19, 1998
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.Dt RESOLVER @LIB_NETWORK_EXT_U@
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.Os BSD 4
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.Sh NAME
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.Nm res_ninit ,
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|
.Nm res_nisourserver ,
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.Nm fp_resstat ,
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.Nm res_npquery ,
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.Nm res_hostalias ,
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.Nm res_nquery ,
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.Nm res_nsearch ,
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.Nm res_nquerydomain ,
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.Nm res_nmkquery ,
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.Nm res_nsend ,
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.Nm res_nupdate ,
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.Nm res_nmkupdate ,
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.Nm res_nclose ,
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.Nm res_nsendsigned ,
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.Nm res_nsendupdate ,
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.Nm res_findzonecut ,
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.Nm dn_comp ,
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.Nm dn_expand ,
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.Nm hstrerror ,
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.Nm res_init ,
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.Nm res_isourserver ,
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.Nm p_nquery ,
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.Mm p_query ,
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.Mm hostalias ,
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.Nm res_query ,
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.Nm res_search ,
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.Nm res_querydomain ,
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.Nm res_mkquery ,
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.Nm res_send ,
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.Nm res_update ,
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.Nm res_close ,
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.Nm herror
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.Nd resolver routines
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|
.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <netinet/in.h>
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.Fd #include <arpa/nameser.h>
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.Fd #include <resolv.h>
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.Fn res_ninit "res_state statp"
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.Fn res_nisourserver "const res_state statp" "const struct sockaddr_in *addr"
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.Fn fp_resstat "const res_state statp" "FILE *fp"
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.Fn res_npquery "const res_state statp" "const u_char *msg" "int msglen" "FILE *fp"
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.Fn res_hostalias "const res_state statp" "const char *name" "char *buf" "size_t buflen"
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.Fn res_nquery "res_state statp" "const char *dname" "int class" "int type" "u_char *answer" "int anslen"
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.Fn res_nsearch "res_state statp" "const char *dname" "int class" "int type" "u_char * answer" "int anslen"
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.Fn res_nquerydomain "res_state statp" "const char *name" "const char *domain" "int class" "int type" "u_char *answer" "int anslen"
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.Fn res_nmkquery "res_state statp, int op, const char *dname" "int class" "int type" "const u_char *data" "int datalen" "const u_char *newrr" "u_char *buf" "int buflen"
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.Fn res_nsend "res_state statp" "const u_char *msg" "int msglen" "u_char *answer" "int anslen"
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.Fn res_nupdate "res_state statp" "ns_updrec *rrecp_in"
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.Fn res_nmkupdate "res_state statp" "ns_updrec *rrecp_in" "u_char *buf" "int buflen"
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.Fn res_nclose "res_state statp"
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.Fn res_nsendsigned "res_state statp" "const u_char *msg" "int msglen" "ns_tsig_key *key" "u_char *answer" "int anslen"
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.Fn res_findzonecut "res_state statp" "const char *dname" "ns_class class" "int options" "char *zname" "size_t zsize" "struct in_addr *addrs" "int naddrs"
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.Fn res_nsendupdate "res_state statp" "ns_updrec *rrecp_in" "ns_tsig_key *key" "char *zname" "struct in_addr addr"
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|
.Fn dn_comp "const char *exp_dn" "u_char *comp_dn" "int length" "u_char **dnptrs, **lastdnptr"
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|
.Fn dn_expand "const u_char *msg, *eomorig, *comp_dn" "char *exp_dn" "int length"
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|
.Fn hstrerror "int err"
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|
.Sh DEPRECATED
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.nr nS 1
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.Fd #include <sys/types.h>
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.Fd #include <netinet/in.h>
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.Fd #include <arpa/nameser.h>
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.Fd #include <resolv.h>
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|
.Fn res_init "void"
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.Fn res_isourserver "const struct sockaddr_in *addr"
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.Fn p_nquery "const u_char *msg" "int msglen" "FILE *fp"
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|
.Fn p_query "const u_char *msg" "FILE *fp"
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.Fn hostalias "const char *name"
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.Fn res_query "const char *dname" "int class, type" "u_char *answer" "int anslen"
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.Fn res_search "const char *dname" "int class, type" "u_char *answer" "int anslen"
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.Fn res_querydomain "const char *name" "const char *domain" "int class" "int type" "u_char *answer" "int anslen"
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.Fn res_mkquery "int op" "const char *dname, int class, type" "const char *data" "int datalen" "struct rrec *newrr" "u_char *buf" "int buflen"
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.Fn res_send "const u_char *msg" "int msglen" "u_char *answer" "int anslen"
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.Fn res_update "ns_updrec *rrecp_in"
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.Fn res_close "void"
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.Fn herror "const char *s"
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.Sh DESCRIPTION
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|
These routines are used for making, sending and interpreting
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query and reply messages with Internet domain name servers.
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.Pp
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|
State information is kept in
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.Fa statp
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and is used to control the behavior of these functions.
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|
.Fa statp
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should be set to all zeros prior to the first call to any of these functions.
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.Pp
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|
The functions
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.Fn res_init ,
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.Fn res_isourserver ,
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.Fn p_nquery ,
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.Fn p_query ,
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.Fn hostalias ,
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.Fn res_query ,
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.Fn res_search ,
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.Fn res_querydomain ,
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.Fn res_mkquery ,
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.Fn res_send ,
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.Fn res_update ,
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.Fn res_close
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and
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.Fn herror
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are deprecated and are supplied for compatability with old source
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code.
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|
They use global configuration and state information that is
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kept in the structure
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.Ft _res
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rather than that referenced through
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.Ft statp .
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.Pp
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Most of the values in
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.Ft statp
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and
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.Ft _res
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are initialized on the first call to
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.Fn res_ninit
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/
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.Fn res_init
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to reasonable defaults and can be ignored.
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Options
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stored in
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.Ft statp->options
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/
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.Ft _res.options
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are defined in
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.Pa resolv.h
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and are as follows.
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Options are stored as a simple bit mask containing the bitwise
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.Dq OR
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of the options enabled.
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.Bl -tag -width "RES_DEB"
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.It Dv RES_INIT
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True if the initial name server address and default domain name are
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initialized (i.e.,
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.Fn res_ninit
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/
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.Fn res_init
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|
has been called).
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.It Dv RES_DEBUG
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|
Print debugging messages.
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.It Dv RES_AAONLY
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|
Accept authoritative answers only.
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should continue until it finds an authoritative answer or finds an error.
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Currently this is not implemented.
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.It Dv RES_USEVC
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Use TCP connections for queries instead of UDP datagrams.
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.It Dv RES_STAYOPEN
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Used with
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.Dv RES_USEVC
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|
to keep the TCP connection open between queries.
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This is useful only in programs that regularly do many queries.
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|
UDP should be the normal mode used.
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.It Dv RES_IGNTC
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|
Ignore truncation errors, i.e., don't retry with TCP.
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.It Dv RES_RECURSE
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Set the recursion-desired bit in queries.
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|
This is the default.
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|
(\c
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|
.Fn res_nsend
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|
/
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|
.Fn res_send
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|
does not do iterative queries and expects the name server
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|
to handle recursion.)
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.It Dv RES_DEFNAMES
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|
If set,
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.Fn res_nsearch
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|
/
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.Fn res_search
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|
will append the default domain name to single-component names
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|
(those that do not contain a dot).
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|
This option is enabled by default.
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.It Dv RES_DNSRCH
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|
If this option is set,
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.Fn res_nsearch
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|
/
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.Fn res_search
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|
will search for host names in the current domain and in parent domains; see
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.Xr hostname @DESC_EXT@ .
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|
This is used by the standard host lookup routine
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.Xr gethostbyname @LIB_NETWORK_EXT@ .
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|
This option is enabled by default.
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.It Dv RES_NOALIASES
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|
This option turns off the user level aliasing feature controlled by
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the
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.Ev HOSTALIASES
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environment variable.
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|
Network daemons should set this option.
|
|
.It Dv RES_USE_INET6
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|
This option causes
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|
.Xr gethostbyname @LIB_NETWORK_EXT@
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|
to look for AAAA records before looking for A records if none are found.
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|
.It Dv RES_ROTATE
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|
This options causes the
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|
.Fn res_nsend
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|
/
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.Fn res_send
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|
to rotate the list of nameservers in
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|
.Fa statp->nsaddr_list
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|
/
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|
.Fa _res.nsaddr_list .
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|
.It Dv RES_KEEPTSIG
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|
This option causes
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|
.Fn res_nsendsigned
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|
to leave the message unchanged after TSIG verification; otherwise the TSIG
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|
record would be removed and the header updated.
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|
.El
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|
.Pp
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|
The
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|
.Fn res_ninit
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|
/
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|
.Fn res_init
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|
routine
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|
reads the configuration file (if any; see
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.Xr resolver @FORMAT_EXT@ )
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|
to get the default domain name, search list and
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the Internet address of the local name server(s).
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|
If no server is configured, the host running the resolver is tried.
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|
The current domain name is defined by the hostname
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|
if not specified in the configuration file;
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|
it can be overridden by the environment variable
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|
.Ev LOCALDOMAIN .
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|
This environment variable may contain several blank-separated
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|
tokens if you wish to override the
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|
.Dq search list
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|
on a per-process basis. This is similar to the
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|
.Ic search
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|
command in the configuration file.
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|
Another environment variable
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|
.Pq Dq Ev RES_OPTIONS
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|
can be set to override certain internal resolver options which are otherwise
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|
set by changing fields in the
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|
.Ft statp
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|
/
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|
.Ft _res
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|
structure or are inherited from the configuration file's
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|
.Ic options
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|
command. The syntax of the
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|
.Dq Ev RES_OPTIONS
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|
environment variable is explained in
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|
.Xr resolver @FORMAT_EXT@ .
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|
Initialization normally occurs on the first call
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to one of the other resolver routines.
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|
.Pp
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|
The
|
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.Fn res_nquery
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/
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|
.Fn res_query
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|
functions provides interfaces to the server query mechanism.
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They constructs a query, sends it to the local server,
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|
awaits a response, and makes preliminary checks on the reply.
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|
The query requests information of the specified
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.Fa type
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and
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|
.Fa class
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|
for the specified fully-qualified domain name
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|
.Fa dname .
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|
The reply message is left in the
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|
.Fa answer
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|
buffer with length
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|
.Fa anslen
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|
supplied by the caller.
|
|
.Fn res_nquery
|
|
/
|
|
.Fn res_query
|
|
return -1 on error or the length of the answer.
|
|
.Pp
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|
The
|
|
.Fn res_nsearch
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|
/
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.Fn res_search
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routines make a query and awaits a response like
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|
.Fn res_nquery
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|
/
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|
.Fn res_query ,
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|
but in addition, it implements the default and search rules
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|
controlled by the
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.Dv RES_DEFNAMES
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|
and
|
|
.Dv RES_DNSRCH
|
|
options.
|
|
It returns the length of the first successful reply which is stored in
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|
.Ft answer
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|
or -1 on error.
|
|
.Pp
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|
The remaining routines are lower-level routines used by
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.Fn res_nquery
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|
/
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|
.Fn res_query .
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|
The
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.Fn res_nmkquery
|
|
/
|
|
.Fn res_mkquery
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|
functions
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|
constructs a standard query message and places it in
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|
.Fa buf .
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|
It returns the size of the query, or \-1 if the query is
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|
larger than
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|
.Fa buflen .
|
|
The query type
|
|
.Fa op
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|
is usually
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|
.Dv QUERY ,
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|
but can be any of the query types defined in
|
|
.Pa <arpa/nameser.h> .
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|
The domain name for the query is given by
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|
.Fa dname .
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|
.Fa Newrr
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|
is currently unused but is intended for making update messages.
|
|
.Pp
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|
The
|
|
.Fn res_nsend
|
|
/
|
|
.Fn res_send
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|
/
|
|
.Fn res_nsendsigned
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|
routines
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|
sends a pre-formatted query and returns an answer.
|
|
It will call
|
|
.Fn res_ninit
|
|
/
|
|
.Fn res_init
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|
if
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|
.Dv RES_INIT
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|
is not set, send the query to the local name server, and
|
|
handle timeouts and retries. Additionally,
|
|
.Fn res_nsendsigned
|
|
will use TSIG signatures to add authentication to the query and verify the
|
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response. In this case, only one nameserver will be contacted.
|
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The length of the reply message is returned, or \-1 if there were errors.
|
|
.Pp
|
|
.Fn res_nquery
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|
/
|
|
.Fn res_query ,
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|
.Fn res_nsearch
|
|
/
|
|
.Fn res_search
|
|
and
|
|
.Fn res_nsend
|
|
/
|
|
.Fn res_send
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|
return a length that may be bigger than
|
|
.Fa anslen .
|
|
In that case the query should be retried with a bigger buffer.
|
|
NOTE the answer to the second query may be larger still so supplying
|
|
a buffer that bigger that the answer returned by the previous
|
|
query is recommended.
|
|
.Pp
|
|
.Fa answer
|
|
MUST be big enough to receive a maximum UDP response from the server or
|
|
parts of the answer will be silently discarded.
|
|
The default maximum UDP response size is 512 bytes.
|
|
.Pp
|
|
The functions
|
|
.Fn res_nisourserver
|
|
/
|
|
.Fn res_isourserver
|
|
return true when
|
|
.Fa inp
|
|
is one of the servers in
|
|
.Fa statp->nsaddr_list
|
|
/
|
|
.Fa _res.nsaddr_list .
|
|
.Pp
|
|
The functions
|
|
.Fn res_npquery
|
|
/
|
|
.Fn p_nquery
|
|
/
|
|
.Fn p_query
|
|
print out the query and any answer in
|
|
.Fa msg
|
|
on
|
|
.Fa fp .
|
|
.Fn p_query
|
|
is equivalent to
|
|
.Fn p_nquery
|
|
with
|
|
.Fa msglen
|
|
set to 512.
|
|
.Pp
|
|
The function
|
|
.Fn fp_resstat
|
|
prints out the active flag bits in
|
|
.Fa statp->options
|
|
preceeded by the text ";; res options:" on
|
|
.Fa file .
|
|
.Pp
|
|
The functions
|
|
.Fn res_hostalias
|
|
/
|
|
.Fn hostalias
|
|
lookup up name in the file referred to by the
|
|
.Ev HOSTALIASES files return a fully qualified hostname if found or NULL if
|
|
not found or an error occurred.
|
|
.Fn res_hostalias
|
|
uses
|
|
.Fa buf
|
|
to store the result in,
|
|
.Fn hostalias
|
|
uses a static buffer.
|
|
.Pp
|
|
The functions
|
|
.Fn res_nupdate
|
|
/
|
|
.Fn res_update
|
|
take a list of ns_updrec
|
|
.Fa rrecp_in .
|
|
Identifies the containing zone for each record and groups the records
|
|
according to containing zone maintaining in zone order then sends and
|
|
update request to the servers for these zones.
|
|
The number of zones updated is returned or -1 on error.
|
|
.Pp
|
|
The function
|
|
.Fn res_findzonecut
|
|
discovers the closest enclosing zone cut for a specified domain name,
|
|
and finds the IP addresses of the zone's master servers.
|
|
.Pp
|
|
The function
|
|
.Fn res_nsendupdate
|
|
is used to perform TSIG authenticated dynamic update operations.
|
|
.Fn res_nsendupdate
|
|
sends a dynamic update to the specified IP address, authenticating the update
|
|
if the key is not NULL.
|
|
.Pp
|
|
The functions
|
|
.Fn res_nmkupdate
|
|
/
|
|
.Fn res_mkupdate
|
|
take a linked list of ns_updrec
|
|
.Fa rrecp_in
|
|
and construct a UPDATE message in
|
|
.Fa buf .
|
|
.Fn res_nmkupdate
|
|
/
|
|
.Fn res_mkupdate
|
|
return the length of the constructed message on no error or one of the
|
|
following error values.
|
|
.Bl -inset -width "-5"
|
|
.It -1
|
|
An error occurred parsing
|
|
.Fa rrecp_in .
|
|
.It -2
|
|
The buffer
|
|
.Fa buf
|
|
was too small.
|
|
.It -3
|
|
The first record was not a zone section or there was a section order problem.
|
|
The section order is S_ZONE, S_PREREQ and S_UPDATE.
|
|
.It -4
|
|
A number overflow occurred.
|
|
.It -5
|
|
Unknown operation or no records.
|
|
.El
|
|
.Pp
|
|
The functions
|
|
.Fn res_nclose
|
|
/
|
|
.Fn res_close
|
|
close any open files referenced through
|
|
.Fa statp
|
|
/
|
|
.Fa _res .
|
|
.Pp
|
|
The
|
|
.Fn dn_comp
|
|
function
|
|
compresses the domain name
|
|
.Fa exp_dn
|
|
and stores it in
|
|
.Fa comp_dn .
|
|
The size of the compressed name is returned or \-1 if there were errors.
|
|
The size of the array pointed to by
|
|
.Fa comp_dn
|
|
is given by
|
|
.Fa length .
|
|
The compression uses
|
|
an array of pointers
|
|
.Fa dnptrs
|
|
to previously-compressed names in the current message.
|
|
The first pointer points to
|
|
to the beginning of the message and the list ends with
|
|
.Dv NULL .
|
|
The limit to the array is specified by
|
|
.Fa lastdnptr .
|
|
A side effect of
|
|
.Fn dn_comp
|
|
is to update the list of pointers for labels inserted into the message
|
|
as the name is compressed. If
|
|
.Fa dnptr
|
|
is
|
|
.Dv NULL ,
|
|
names are not compressed. If
|
|
.Fa lastdnptr
|
|
is
|
|
.Dv NULL ,
|
|
the list of labels is not updated.
|
|
.Pp
|
|
The
|
|
.Fn dn_expand
|
|
entry
|
|
expands the compressed domain name
|
|
.Fa comp_dn
|
|
to a full domain name.
|
|
The compressed name is contained in a query or reply message;
|
|
.Fa msg
|
|
is a pointer to the beginning of the message.
|
|
The uncompressed name is placed in the buffer indicated by
|
|
.Fa exp_dn
|
|
which is of size
|
|
.Fa length .
|
|
The size of compressed name is returned or \-1 if there was an error.
|
|
.Pp
|
|
The variables
|
|
.Ft statp->res_h_errno
|
|
/
|
|
.Ft _res.res_h_errno
|
|
and external variable
|
|
.Ft h_errno
|
|
is set whenever an error occurs during resolver operation. The following
|
|
definitions are given in
|
|
.Pa <netdb.h> :
|
|
.Bd -literal
|
|
#define NETDB_INTERNAL -1 /* see errno */
|
|
#define NETDB_SUCCESS 0 /* no problem */
|
|
#define HOST_NOT_FOUND 1 /* Authoritative Answer Host not found */
|
|
#define TRY_AGAIN 2 /* Non-Authoritative not found, or SERVFAIL */
|
|
#define NO_RECOVERY 3 /* Non-Recoverable: FORMERR, REFUSED, NOTIMP */
|
|
#define NO_DATA 4 /* Valid name, no data for requested type */
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Fn herror
|
|
function writes a message to the diagnostic output consisting of the string
|
|
parameter
|
|
.Fa s ,
|
|
the constant string ": ", and a message corresponding to the value of
|
|
.Ft h_errno .
|
|
.Pp
|
|
The
|
|
.Fn hstrerror
|
|
function returns a string which is the message text corresponding to the
|
|
value of the
|
|
.Fa err
|
|
parameter.
|
|
.Sh FILES
|
|
.Bl -tag -width "/etc/resolv.conf "
|
|
.It Pa /etc/resolv.conf
|
|
See
|
|
.Xr resolver @FORMAT_EXT@ .
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr gethostbyname @LIB_NETWORK_EXT@ ,
|
|
.Xr hostname @DESC_EXT@ ,
|
|
.Xr @INDOT@named @SYS_OPS_EXT@ ,
|
|
.Xr resolver @FORMAT_EXT@ ;
|
|
RFC1032, RFC1033, RFC1034, RFC1035, RFC974;
|
|
SMM:11,
|
|
.Dq Name Server Operations Guide for Sy BIND
|