diff --git a/include/resolv.h b/include/resolv.h index 40ca2e8a467f..f32f52bab431 100644 --- a/include/resolv.h +++ b/include/resolv.h @@ -1,503 +1,504 @@ /*- * SPDX-License-Identifier: (ISC AND BSD-3-Clause) * * Portions Copyright (C) 2004, 2005, 2008, 2009 Internet Systems Consortium, Inc. ("ISC") * Portions Copyright (C) 1995-2003 Internet Software Consortium. * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR * PERFORMANCE OF THIS SOFTWARE. */ /* * Copyright (c) 1983, 1987, 1989 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /*% * $Id: resolv.h,v 1.30 2009/03/03 01:52:48 each Exp $ */ #ifndef _RESOLV_H_ #define _RESOLV_H_ #include #include #include #include #include +#include #include /*% * Revision information. This is the release date in YYYYMMDD format. * It can change every day so the right thing to do with it is use it * in preprocessor commands such as "#if (__RES > 19931104)". Do not * compare for equality; rather, use it to determine whether your resolver * is new enough to contain a certain feature. */ #define __RES 20090302 /*% * This used to be defined in res_query.c, now it's in herror.c. * [XXX no it's not. It's in irs/irs_data.c] * It was * never extern'd by any *.h file before it was placed here. For thread * aware programs, the last h_errno value set is stored in res->h_errno. * * XXX: There doesn't seem to be a good reason for exposing RES_SET_H_ERRNO * (and __h_errno_set) to the public via . * XXX: __h_errno_set is really part of IRS, not part of the resolver. * If somebody wants to build and use a resolver that doesn't use IRS, * what do they do? Perhaps something like * #ifdef WANT_IRS * # define RES_SET_H_ERRNO(r,x) __h_errno_set(r,x) * #else * # define RES_SET_H_ERRNO(r,x) (h_errno = (r)->res_h_errno = (x)) * #endif */ #define RES_SET_H_ERRNO(r,x) __h_errno_set(r,x) struct __res_state; /*%< forward */ __BEGIN_DECLS void __h_errno_set(struct __res_state *, int); __END_DECLS /*% * Resolver configuration file. * Normally not present, but may contain the address of the * initial name server(s) to query and the domain search list. */ #ifndef _PATH_RESCONF #define _PATH_RESCONF "/etc/resolv.conf" #endif typedef enum { res_goahead, res_nextns, res_modified, res_done, res_error } res_sendhookact; typedef res_sendhookact (*res_send_qhook)(struct sockaddr * const *, const u_char **, int *, u_char *, int, int *); typedef res_sendhookact (*res_send_rhook)(const struct sockaddr *, const u_char *, int, u_char *, int, int *); struct res_sym { int number; /*%< Identifying number, like T_MX */ const char * name; /*%< Its symbolic name, like "MX" */ const char * humanname; /*%< Its fun name, like "mail exchanger" */ }; /*% * Global defines and variables for resolver stub. */ #define MAXNS 3 /*%< max # name servers we'll track */ #define MAXDFLSRCH 3 /*%< # default domain levels to try */ #define MAXDNSRCH 6 /*%< max # domains in search path */ #define LOCALDOMAINPARTS 2 /*%< min levels in name that is "local" */ #define RES_TIMEOUT 5 /*%< min. seconds between retries */ #define MAXRESOLVSORT 10 /*%< number of net to sort on */ #define RES_MAXNDOTS 15 /*%< should reflect bit field size */ #define RES_MAXRETRANS 30 /*%< only for resolv.conf/RES_OPTIONS */ #define RES_MAXRETRY 5 /*%< only for resolv.conf/RES_OPTIONS */ #define RES_DFLRETRY 2 /*%< Default #/tries. */ #define RES_MAXTIME 65535 /*%< Infinity, in milliseconds. */ struct __res_state_ext; struct __res_state { int retrans; /*%< retransmission time interval */ int retry; /*%< number of times to retransmit */ /* * XXX: If `sun' is defined, `options' and `pfcode' are * defined as u_int in original BIND9 distribution. However, * it breaks binary backward compatibility against FreeBSD's * resolver. So, we changed not to see `sun'. */ #if defined(sun) && 0 u_int options; /*%< option flags - see below. */ #else u_long options; /*%< option flags - see below. */ #endif int nscount; /*%< number of name servers */ struct sockaddr_in nsaddr_list[MAXNS]; /*%< address of name server */ #define nsaddr nsaddr_list[0] /*%< for backward compatibility */ u_short id; /*%< current message id */ char *dnsrch[MAXDNSRCH+1]; /*%< components of domain to search */ char defdname[256]; /*%< default domain (deprecated) */ #if defined(sun) && 0 u_int pfcode; /*%< RES_PRF_ flags - see below. */ #else u_long pfcode; /*%< RES_PRF_ flags - see below. */ #endif unsigned ndots:4; /*%< threshold for initial abs. query */ unsigned nsort:4; /*%< number of elements in sort_list[] */ char unused[3]; struct { struct in_addr addr; u_int32_t mask; } sort_list[MAXRESOLVSORT]; res_send_qhook qhook; /*%< query hook */ res_send_rhook rhook; /*%< response hook */ int res_h_errno; /*%< last one set for this context */ int _vcsock; /*%< PRIVATE: for res_send VC i/o */ u_int _flags; /*%< PRIVATE: see below */ u_int _pad; /*%< make _u 64 bit aligned */ union { /* On an 32-bit arch this means 512b total. */ char pad[72 - 4*sizeof (int) - 3*sizeof (void *)]; struct { u_int16_t nscount; u_int16_t nstimes[MAXNS]; /*%< ms. */ int nssocks[MAXNS]; struct __res_state_ext *ext; /*%< extension for IPv6 */ } _ext; } _u; u_char *_rnd; /*%< PRIVATE: random state */ }; typedef struct __res_state *res_state; union res_sockaddr_union { struct sockaddr_in sin; #ifdef IN6ADDR_ANY_INIT struct sockaddr_in6 sin6; #endif #ifdef ISC_ALIGN64 int64_t __align64; /*%< 64bit alignment */ #else int32_t __align32; /*%< 32bit alignment */ #endif char __space[128]; /*%< max size */ }; /*% * Resolver flags (used to be discrete per-module statics ints). */ #define RES_F_VC 0x00000001 /*%< socket is TCP */ #define RES_F_CONN 0x00000002 /*%< socket is connected */ #define RES_F_EDNS0ERR 0x00000004 /*%< EDNS0 caused errors */ #define RES_F__UNUSED 0x00000008 /*%< (unused) */ #define RES_F_LASTMASK 0x000000F0 /*%< ordinal server of last res_nsend */ #define RES_F_LASTSHIFT 4 /*%< bit position of LASTMASK "flag" */ #define RES_GETLAST(res) (((res)._flags & RES_F_LASTMASK) >> RES_F_LASTSHIFT) /* res_findzonecut2() options */ #define RES_EXHAUSTIVE 0x00000001 /*%< always do all queries */ #define RES_IPV4ONLY 0x00000002 /*%< IPv4 only */ #define RES_IPV6ONLY 0x00000004 /*%< IPv6 only */ /*% * Resolver options (keep these in synch with res_debug.c, please) */ #define RES_INIT 0x00000001 /*%< address initialized */ #define RES_DEBUG 0x00000002 /*%< print debug messages */ #define RES_AAONLY 0x00000004 /*%< authoritative answers only (!IMPL)*/ #define RES_USEVC 0x00000008 /*%< use virtual circuit */ #define RES_PRIMARY 0x00000010 /*%< query primary server only (!IMPL) */ #define RES_IGNTC 0x00000020 /*%< ignore truncation errors */ #define RES_RECURSE 0x00000040 /*%< recursion desired */ #define RES_DEFNAMES 0x00000080 /*%< use default domain name */ #define RES_STAYOPEN 0x00000100 /*%< Keep TCP socket open */ #define RES_DNSRCH 0x00000200 /*%< search up local domain tree */ #define RES_INSECURE1 0x00000400 /*%< type 1 security disabled */ #define RES_INSECURE2 0x00000800 /*%< type 2 security disabled */ #define RES_NOALIASES 0x00001000 /*%< shuts off HOSTALIASES feature */ #define RES_USE_INET6 0x00002000 /*%< use/map IPv6 in gethostbyname() */ #define RES_ROTATE 0x00004000 /*%< rotate ns list after each query */ #define RES_NOCHECKNAME 0x00008000 /*%< do not check names for sanity. */ #define RES_KEEPTSIG 0x00010000 /*%< do not strip TSIG records */ #define RES_BLAST 0x00020000 /*%< blast all recursive servers */ #define RES_NSID 0x00040000 /*%< request name server ID */ #define RES_NOTLDQUERY 0x00100000 /*%< don't unqualified name as a tld */ #define RES_USE_DNSSEC 0x00200000 /*%< use DNSSEC using OK bit in OPT */ /* #define RES_DEBUG2 0x00400000 */ /* nslookup internal */ /* KAME extensions: use higher bit to avoid conflict with ISC use */ #define RES_USE_DNAME 0x10000000 /*%< use DNAME */ #define RES_USE_EDNS0 0x40000000 /*%< use EDNS0 if configured */ #define RES_NO_NIBBLE2 0x80000000 /*%< disable alternate nibble lookup */ #define RES_DEFAULT (RES_RECURSE | RES_DEFNAMES | \ RES_DNSRCH | RES_NO_NIBBLE2) /*% * Resolver "pfcode" values. Used by dig. */ #define RES_PRF_STATS 0x00000001 #define RES_PRF_UPDATE 0x00000002 #define RES_PRF_CLASS 0x00000004 #define RES_PRF_CMD 0x00000008 #define RES_PRF_QUES 0x00000010 #define RES_PRF_ANS 0x00000020 #define RES_PRF_AUTH 0x00000040 #define RES_PRF_ADD 0x00000080 #define RES_PRF_HEAD1 0x00000100 #define RES_PRF_HEAD2 0x00000200 #define RES_PRF_TTLID 0x00000400 #define RES_PRF_HEADX 0x00000800 #define RES_PRF_QUERY 0x00001000 #define RES_PRF_REPLY 0x00002000 #define RES_PRF_INIT 0x00004000 #define RES_PRF_TRUNC 0x00008000 /* 0x00010000 */ /* Things involving an internal (static) resolver context. */ __BEGIN_DECLS extern struct __res_state *__res_state(void); __END_DECLS #define _res (*__res_state()) #ifndef __BIND_NOSTATIC #define fp_nquery __fp_nquery #define fp_query __fp_query #define hostalias __hostalias #define p_query __p_query #define res_close __res_close #define res_init __res_init #define res_isourserver __res_isourserver #define res_mkquery __res_mkquery #define res_opt __res_opt #define res_query __res_query #define res_querydomain __res_querydomain #define res_search __res_search #define res_send __res_send #define res_sendsigned __res_sendsigned __BEGIN_DECLS void fp_nquery(const u_char *, int, FILE *); void fp_query(const u_char *, FILE *); const char * hostalias(const char *); void p_query(const u_char *); void res_close(void); int res_init(void); int res_isourserver(const struct sockaddr_in *); int res_mkquery(int, const char *, int, int, const u_char *, int, const u_char *, u_char *, int); int res_opt(int, u_char *, int, int); int res_query(const char *, int, int, u_char *, int); int res_querydomain(const char *, const char *, int, int, u_char *, int); int res_search(const char *, int, int, u_char *, int); int res_send(const u_char *, int, u_char *, int); int res_sendsigned(const u_char *, int, ns_tsig_key *, u_char *, int); __END_DECLS #endif #if !defined(SHARED_LIBBIND) || defined(LIB) /* * If libbind is a shared object (well, DLL anyway) * these externs break the linker when resolv.h is * included by a lib client (like named) * Make them go away if a client is including this * */ extern const struct res_sym __p_key_syms[]; extern const struct res_sym __p_cert_syms[]; extern const struct res_sym __p_class_syms[]; extern const struct res_sym __p_type_syms[]; extern const struct res_sym __p_rcode_syms[]; #endif /* SHARED_LIBBIND */ #define b64_ntop __b64_ntop #define b64_pton __b64_pton #define dn_comp __dn_comp #define dn_count_labels __dn_count_labels #define dn_expand __dn_expand #define dn_skipname __dn_skipname #define fp_resstat __fp_resstat #define loc_aton __loc_aton #define loc_ntoa __loc_ntoa #define p_cdname __p_cdname #define p_cdnname __p_cdnname #define p_class __p_class #define p_fqname __p_fqname #define p_fqnname __p_fqnname #define p_option __p_option #define p_secstodate __p_secstodate #define p_section __p_section #define p_time __p_time #define p_type __p_type #define p_rcode __p_rcode #define p_sockun __p_sockun #define putlong __putlong #define putshort __putshort #define res_dnok __res_dnok #if 0 #define res_findzonecut __res_findzonecut #endif #define res_findzonecut2 __res_findzonecut2 #define res_hnok __res_hnok #define res_hostalias __res_hostalias #define res_mailok __res_mailok #define res_nameinquery __res_nameinquery #define res_nclose __res_nclose #define res_ninit __res_ninit #define res_nmkquery __res_nmkquery #define res_pquery __res_pquery #define res_nquery __res_nquery #define res_nquerydomain __res_nquerydomain #define res_nsearch __res_nsearch #define res_nsend __res_nsend #if 0 #define res_nsendsigned __res_nsendsigned #endif #define res_nisourserver __res_nisourserver #define res_ownok __res_ownok #define res_queriesmatch __res_queriesmatch #define res_rndinit __res_rndinit #define res_randomid __res_randomid #define res_nrandomid __res_nrandomid #define sym_ntop __sym_ntop #define sym_ntos __sym_ntos #define sym_ston __sym_ston #define res_nopt __res_nopt #define res_nopt_rdata __res_nopt_rdata #define res_ndestroy __res_ndestroy #define res_nametoclass __res_nametoclass #define res_nametotype __res_nametotype #define res_setservers __res_setservers #define res_getservers __res_getservers #if 0 #define res_buildprotolist __res_buildprotolist #define res_destroyprotolist __res_destroyprotolist #define res_destroyservicelist __res_destroyservicelist #define res_get_nibblesuffix __res_get_nibblesuffix #define res_get_nibblesuffix2 __res_get_nibblesuffix2 #endif #define res_ourserver_p __res_ourserver_p #if 0 #define res_protocolname __res_protocolname #define res_protocolnumber __res_protocolnumber #endif #define res_send_setqhook __res_send_setqhook #define res_send_setrhook __res_send_setrhook #if 0 #define res_servicename __res_servicename #define res_servicenumber __res_servicenumber #endif __BEGIN_DECLS int res_hnok(const char *); int res_ownok(const char *); int res_mailok(const char *); int res_dnok(const char *); int sym_ston(const struct res_sym *, const char *, int *); const char * sym_ntos(const struct res_sym *, int, int *); const char * sym_ntop(const struct res_sym *, int, int *); int b64_ntop(u_char const *, size_t, char *, size_t); int b64_pton(char const *, u_char *, size_t); int loc_aton(const char *, u_char *); const char * loc_ntoa(const u_char *, char *); int dn_skipname(const u_char *, const u_char *); void putlong(u_int32_t, u_char *); void putshort(u_int16_t, u_char *); #ifndef __ultrix__ u_int16_t _getshort(const u_char *); u_int32_t _getlong(const u_char *); #endif const char * p_class(int); const char * p_time(u_int32_t); const char * p_type(int); const char * p_rcode(int); const char * p_sockun(union res_sockaddr_union, char *, size_t); const u_char * p_cdnname(const u_char *, const u_char *, int, FILE *); const u_char * p_cdname(const u_char *, const u_char *, FILE *); const u_char * p_fqnname(const u_char *, const u_char *, int, char *, int); const u_char * p_fqname(const u_char *, const u_char *, FILE *); const char * p_option(u_long); char * p_secstodate(u_long); int dn_count_labels(const char *); int dn_comp(const char *, u_char *, int, u_char **, u_char **); int dn_expand(const u_char *, const u_char *, const u_char *, char *, int); void res_rndinit(res_state); u_int res_randomid(void); u_int res_nrandomid(res_state); int res_nameinquery(const char *, int, int, const u_char *, const u_char *); int res_queriesmatch(const u_char *, const u_char *, const u_char *, const u_char *); const char * p_section(int, int); /* Things involving a resolver context. */ int res_ninit(res_state); int res_nisourserver(const res_state, const struct sockaddr_in *); void fp_resstat(const res_state, FILE *); void res_pquery(const res_state, const u_char *, int, FILE *); const char * res_hostalias(const res_state, const char *, char *, size_t); int res_nquery(res_state, const char *, int, int, u_char *, int); int res_nsearch(res_state, const char *, int, int, u_char *, int); int res_nquerydomain(res_state, const char *, const char *, int, int, u_char *, int); int res_nmkquery(res_state, int, const char *, int, int, const u_char *, int, const u_char *, u_char *, int); int res_nsend(res_state, const u_char *, int, u_char *, int); #if 0 int res_nsendsigned(res_state, const u_char *, int, ns_tsig_key *, u_char *, int); int res_findzonecut(res_state, const char *, ns_class, int, char *, size_t, struct in_addr *, int); #endif int res_findzonecut2(res_state, const char *, ns_class, int, char *, size_t, union res_sockaddr_union *, int); void res_nclose(res_state); int res_nopt(res_state, int, u_char *, int, int); int res_nopt_rdata(res_state, int, u_char *, int, u_char *, u_short, u_short, u_char *); void res_send_setqhook(res_send_qhook); void res_send_setrhook(res_send_rhook); int __res_vinit(res_state, int); #if 0 void res_destroyservicelist(void); const char * res_servicename(u_int16_t, const char *); const char * res_protocolname(int); void res_destroyprotolist(void); void res_buildprotolist(void); const char * res_get_nibblesuffix(res_state); const char * res_get_nibblesuffix2(res_state); #endif void res_ndestroy(res_state); u_int16_t res_nametoclass(const char *, int *); u_int16_t res_nametotype(const char *, int *); void res_setservers(res_state, const union res_sockaddr_union *, int); int res_getservers(res_state, union res_sockaddr_union *, int); __END_DECLS #endif /* !_RESOLV_H_ */ /*! \file */ diff --git a/lib/libc/net/resolver.3 b/lib/libc/net/resolver.3 index 832fa05e994b..f1220dcf9b7f 100644 --- a/lib/libc/net/resolver.3 +++ b/lib/libc/net/resolver.3 @@ -1,454 +1,451 @@ .\" Copyright (c) 1985, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd September 15, 2022 +.Dd January 8, 2024 .Dt RESOLVER 3 .Os .Sh NAME .Nm res_query , .Nm res_search , .Nm res_mkquery , .Nm res_send , .Nm res_init , .Nm dn_comp , .Nm dn_expand , .Nm dn_skipname , .Nm ns_get16 , .Nm ns_get32 , .Nm ns_put16 , .Nm ns_put32 .Nd resolver routines .Sh LIBRARY .Lb libc .Sh SYNOPSIS -.In sys/types.h -.In netinet/in.h -.In arpa/nameser.h .In resolv.h .Ft int .Fo res_query .Fa "const char *dname" .Fa "int class" .Fa "int type" .Fa "u_char *answer" .Fa "int anslen" .Fc .Ft int .Fo res_search .Fa "const char *dname" .Fa "int class" .Fa "int type" .Fa "u_char *answer" .Fa "int anslen" .Fc .Ft int .Fo res_mkquery .Fa "int op" .Fa "const char *dname" .Fa "int class" .Fa "int type" .Fa "const u_char *data" .Fa "int datalen" .Fa "const u_char *newrr_in" .Fa "u_char *buf" .Fa "int buflen" .Fc .Ft int .Fo res_send .Fa "const u_char *msg" .Fa "int msglen" .Fa "u_char *answer" .Fa "int anslen" .Fc .Ft int .Fn res_init void .Ft int .Fo dn_comp .Fa "const char *exp_dn" .Fa "u_char *comp_dn" .Fa "int length" .Fa "u_char **dnptrs" .Fa "u_char **lastdnptr" .Fc .Ft int .Fo dn_expand .Fa "const u_char *msg" .Fa "const u_char *eomorig" .Fa "const u_char *comp_dn" .Fa "char *exp_dn" .Fa "int length" .Fc .Ft int .Fn dn_skipname "const u_char *comp_dn" "const u_char *eom" .Ft u_int .Fn ns_get16 "const u_char *src" .Ft u_long .Fn ns_get32 "const u_char *src" .Ft void .Fn ns_put16 "u_int src" "u_char *dst" .Ft void .Fn ns_put32 "u_long src" "u_char *dst" .Sh DESCRIPTION These routines are used for making, sending and interpreting query and reply messages with Internet domain name servers. .Pp Global configuration and state information that is used by the resolver routines is kept in the structure .Va _res . Most of the values have reasonable defaults and can be ignored. Options stored in .Va _res.options are defined in .In resolv.h and are as follows. Options are stored as a simple bit mask containing the bitwise ``or'' of the options enabled. .Bl -tag -width RES_USE_INET6 .It Dv RES_INIT True if the initial name server address and default domain name are initialized (i.e., .Fn res_init has been called). .It Dv RES_DEBUG Print debugging messages. .It Dv RES_AAONLY Accept authoritative answers only. With this option, .Fn res_send should continue until it finds an authoritative answer or finds an error. Currently this is not implemented. .It Dv RES_USEVC Use .Tn TCP connections for queries instead of .Tn UDP datagrams. .It Dv RES_STAYOPEN Used with .Dv RES_USEVC to keep the .Tn TCP connection open between queries. This is useful only in programs that regularly do many queries. .Tn UDP should be the normal mode used. .It Dv RES_IGNTC Unused currently (ignore truncation errors, i.e., do not retry with .Tn TCP ) . .It Dv RES_RECURSE Set the recursion-desired bit in queries. This is the default. .Pf ( Fn res_send does not do iterative queries and expects the name server to handle recursion.) .It Dv RES_DEFNAMES If set, .Fn res_search will append the default domain name to single-component names (those that do not contain a dot). This option is enabled by default. .It Dv RES_DNSRCH If this option is set, .Fn res_search will search for host names in the current domain and in parent domains; see .Xr hostname 7 . This is used by the standard host lookup routine .Xr gethostbyname 3 . This option is enabled by default. .It Dv RES_NOALIASES This option turns off the user level aliasing feature controlled by the .Dq Ev HOSTALIASES environment variable. Network daemons should set this option. .It Dv RES_USE_INET6 Enables support for IPv6-only applications. This causes IPv4 addresses to be returned as an IPv4 mapped address. For example, .Li 10.1.1.1 will be returned as .Li ::ffff:10.1.1.1 . The option is meaningful with certain kernel configuration only. .It Dv RES_USE_EDNS0 Enables support for OPT pseudo-RR for EDNS0 extension. With the option, resolver code will attach OPT pseudo-RR into DNS queries, to inform of our receive buffer size. The option will allow DNS servers to take advantage of non-default receive buffer size, and to send larger replies. DNS query packets with EDNS0 extension is not compatible with non-EDNS0 DNS servers. .El .Pp The .Fn res_init routine reads the configuration file (if any; see .Xr resolver 5 ) to get the default domain name, search list and the Internet address of the local name server(s). If no server is configured, the host running the resolver is tried. The current domain name is defined by the hostname if not specified in the configuration file; it can be overridden by the environment variable .Ev LOCALDOMAIN . This environment variable may contain several blank-separated tokens if you wish to override the .Em "search list" on a per-process basis. This is similar to the .Ic search command in the configuration file. Another environment variable .Dq Ev RES_OPTIONS can be set to override certain internal resolver options which are otherwise set by changing fields in the .Va _res structure or are inherited from the configuration file's .Ic options command. The syntax of the .Dq Ev RES_OPTIONS environment variable is explained in .Xr resolver 5 . Initialization normally occurs on the first call to one of the following routines. .Pp The .Fn res_query function provides an interface to the server query mechanism. It constructs a query, sends it to the local server, awaits a response, and makes preliminary checks on the reply. The query requests information of the specified .Fa type and .Fa class for the specified fully-qualified domain name .Fa dname . The reply message is left in the .Fa answer buffer with length .Fa anslen supplied by the caller. .Pp The .Fn res_search routine makes a query and awaits a response like .Fn res_query , but in addition, it implements the default and search rules controlled by the .Dv RES_DEFNAMES and .Dv RES_DNSRCH options. It returns the first successful reply. .Pp The remaining routines are lower-level routines used by .Fn res_query . The .Fn res_mkquery function constructs a standard query message and places it in .Fa buf . It returns the size of the query, or \-1 if the query is larger than .Fa buflen . The query type .Fa op is usually .Dv QUERY , but can be any of the query types defined in .In arpa/nameser.h . The domain name for the query is given by .Fa dname . The .Fa newrr_in argument is currently unused but is intended for making update messages. .Pp The .Fn res_send routine sends a pre-formatted query and returns an answer. It will call .Fn res_init if .Dv RES_INIT is not set, send the query to the local name server, and handle timeouts and retries. The length of the reply message is returned, or \-1 if there were errors. .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 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 .Fn dn_skipname function skips over a compressed domain name, which starts at a location pointed to by .Fa comp_dn . The compressed name is contained in a query or reply message; .Fa eom is a pointer to the end of the message. The size of compressed name is returned or \-1 if there was an error. .Pp The .Fn ns_get16 function gets a 16-bit quantity from a buffer pointed to by .Fa src . .Pp The .Fn ns_get32 function gets a 32-bit quantity from a buffer pointed to by .Fa src . .Pp The .Fn ns_put16 function puts a 16-bit quantity .Fa src to a buffer pointed to by .Fa dst . .Pp The .Fn ns_put32 function puts a 32-bit quantity .Fa src to a buffer pointed to by .Fa dst . .Sh IMPLEMENTATION NOTES This implementation of the resolver is thread-safe, but it will not function properly if the programmer attempts to declare his or her own .Va _res structure in an attempt to replace the per-thread version referred to by that macro. .Pp The following compile-time option can be specified to change the default behavior of resolver routines when necessary. .Bl -tag -width RES_ENFORCE_RFC1034 .It Dv RES_ENFORCE_RFC1034 If this symbol is defined during compile-time, .Fn res_search will enforce RFC 1034 check, namely, disallow using of underscore character within host names. This is used by the standard host lookup routines like .Xr gethostbyname 3 . For compatibility reasons this option is not enabled by default. .El .Sh RETURN VALUES The .Fn res_init function will return 0 on success, or \-1 in a threaded program if per-thread storage could not be allocated. .Pp The .Fn res_mkquery , .Fn res_search , and .Fn res_query functions return the size of the response on success, or \-1 if an error occurs. The integer .Vt h_errno may be checked to determine the reason for error. See .Xr gethostbyname 3 for more information. .Sh FILES .Bl -tag -width /etc/resolv.conf .It Pa /etc/resolv.conf The configuration file, see .Xr resolver 5 . .El .Sh SEE ALSO .Xr gethostbyname 3 , .Xr resolver 5 , .Xr hostname 7 .Pp .%T RFC1032 , .%T RFC1033 , .%T RFC1034 , .%T RFC1035 , .%T RFC974 .Sh HISTORY The .Nm function appeared in .Bx 4.3 .