/* $NetBSD: res_query.c,v 1.16 2015/02/24 17:56:20 christos Exp $ */ /* * Portions Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC") * Portions Copyright (C) 1996-2001, 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) 1988, 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. */ /* * Portions Copyright (c) 1993 by Digital Equipment Corporation. * * Permission to use, copy, modify, and 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, and that * the name of Digital Equipment Corporation not be used in advertising or * publicity pertaining to distribution of the document or software without * specific, written prior permission. * * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT * CORPORATION 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. */ #if defined(LIBC_SCCS) && !defined(lint) static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; static const char rcsid[] = "$Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp $"; #endif /* LIBC_SCCS and not lint */ #include "port_before.h" #include <sys/types.h> #include <sys/param.h> #include <netinet/in.h> #include <arpa/inet.h> #include <arpa/nameser.h> #include <ctype.h> #include <errno.h> #include <netdb.h> #include <resolv.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include "port_after.h" /* Options. Leave them on. */ //#define DEBUG #if PACKETSZ > 1024 #define MAXPACKET PACKETSZ #else #define MAXPACKET 1024 #endif /*% * Formulate a normal query, send, and await answer. * Returned answer is placed in supplied buffer "answer". * Perform preliminary check of answer, returning success only * if no error is indicated and the answer count is nonzero. * Return the size of the response on success, -1 on error. * Error number is left in H_ERRNO. * * Caller must parse answer and determine whether it answers the question. */ int res_nquery(res_state statp, const char *name, /*%< domain name */ int class, int type, /*%< class and type of query */ u_char *answer, /*%< buffer to put answer */ int anslen) /*%< size of answer buffer */ { u_char buf[MAXPACKET]; HEADER *hp = (HEADER *)(void *)answer; u_int oflags; u_char *rdata; int n; oflags = statp->_flags; again: hp->rcode = NOERROR; /*%< default */ #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query(%s, %d, %d)\n", name, class, type); #endif n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, buf, (int)sizeof(buf)); #ifdef RES_USE_EDNS0 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID)) != 0U) { n = res_nopt(statp, n, buf, (int)sizeof(buf), anslen); rdata = &buf[n]; if (n > 0 && (statp->options & RES_NSID) != 0U) { n = res_nopt_rdata(statp, n, buf, (int)sizeof(buf), rdata, NS_OPT_NSID, 0, NULL); } } #endif if (n <= 0) { #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query: mkquery failed\n"); #endif RES_SET_H_ERRNO(statp, NO_RECOVERY); return (n); } n = res_nsend(statp, buf, n, answer, anslen); if (n < 0) { #ifdef RES_USE_EDNS0 /* if the query choked with EDNS0, retry without EDNS0 */ if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { statp->_flags |= RES_F_EDNS0ERR; if (statp->options & RES_DEBUG) printf(";; res_nquery: retry without EDNS0\n"); goto again; } #endif #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query: send error\n"); #endif RES_SET_H_ERRNO(statp, TRY_AGAIN); return (n); } if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", p_rcode(hp->rcode), ntohs(hp->ancount), ntohs(hp->nscount), ntohs(hp->arcount)); #endif switch (hp->rcode) { case NXDOMAIN: RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); break; case SERVFAIL: RES_SET_H_ERRNO(statp, TRY_AGAIN); break; case NOERROR: RES_SET_H_ERRNO(statp, NO_DATA); break; case FORMERR: case NOTIMP: case REFUSED: default: RES_SET_H_ERRNO(statp, NO_RECOVERY); break; } return (-1); } return (n); } /*% * Formulate a normal query, send, and retrieve answer in supplied buffer. * Return the size of the response on success, -1 on error. * If enabled, implement search rules until answer or unrecoverable failure * is detected. Error code, if any, is left in H_ERRNO. */ int res_nsearch(res_state statp, const char *name, /*%< domain name */ int class, int type, /*%< class and type of query */ u_char *answer, /*%< buffer to put answer */ int anslen) /*%< size of answer */ { const char *cp, * const *domain; HEADER *hp = (HEADER *)(void *)answer; char tmp[NS_MAXDNAME]; u_int dots; int trailing_dot, ret, saved_herrno; int got_nodata = 0, got_servfail = 0, root_on_list = 0; int tried_as_is = 0; int searched = 0; errno = 0; RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */ dots = 0; for (cp = name; *cp != '\0'; cp++) dots += (*cp == '.'); trailing_dot = 0; if (cp > name && *--cp == '.') trailing_dot++; /* If there aren't any dots, it could be a user-level alias. */ if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) return (res_nquery(statp, cp, class, type, answer, anslen)); /* * If there are enough dots in the name, let's just give it a * try 'as is'. The threshold can be set with the "ndots" option. * Also, query 'as is', if there is a trailing dot in the name. */ saved_herrno = -1; if (dots >= statp->ndots || trailing_dot) { ret = res_nquerydomain(statp, name, NULL, class, type, answer, anslen); if (ret > 0 || trailing_dot) return (ret); saved_herrno = statp->res_h_errno; tried_as_is++; } /* * We do at least one level of search if * - there is no dot and RES_DEFNAME is set, or * - there is at least one dot, there is no trailing dot, * and RES_DNSRCH is set. */ if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { int done = 0; for (domain = (const char * const *)statp->dnsrch; *domain && !done; domain++) { searched = 1; if (domain[0][0] == '\0' || (domain[0][0] == '.' && domain[0][1] == '\0')) root_on_list++; ret = res_nquerydomain(statp, name, *domain, class, type, answer, anslen); if (ret > 0) return (ret); /* * If no server present, give up. * If name isn't found in this domain, * keep trying higher domains in the search list * (if that's enabled). * On a NO_DATA error, keep trying, otherwise * a wildcard entry of another type could keep us * from finding this entry higher in the domain. * If we get some other error (negative answer or * server failure), then stop searching up, * but try the input name below in case it's * fully-qualified. */ if (errno == ECONNREFUSED) { RES_SET_H_ERRNO(statp, TRY_AGAIN); return (-1); } switch (statp->res_h_errno) { case NO_DATA: got_nodata++; /* FALLTHROUGH */ case HOST_NOT_FOUND: /* keep trying */ break; case TRY_AGAIN: if (hp->rcode == SERVFAIL) { /* try next search element, if any */ got_servfail++; break; } /* FALLTHROUGH */ default: /* anything else implies that we're done */ done++; } /* if we got here for some reason other than DNSRCH, * we only wanted one iteration of the loop, so stop. */ if ((statp->options & RES_DNSRCH) == 0U) done++; } } /* * If the query has not already been tried as is then try it * unless RES_NOTLDQUERY is set and there were no dots. */ if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && !(tried_as_is || root_on_list)) { ret = res_nquerydomain(statp, name, NULL, class, type, answer, anslen); if (ret > 0) return (ret); } /* if we got here, we didn't satisfy the search. * if we did an initial full query, return that query's H_ERRNO * (note that we wouldn't be here if that query had succeeded). * else if we ever got a nodata, send that back as the reason. * else send back meaningless H_ERRNO, that being the one from * the last DNSRCH we did. */ if (saved_herrno != -1) RES_SET_H_ERRNO(statp, saved_herrno); else if (got_nodata) RES_SET_H_ERRNO(statp, NO_DATA); else if (got_servfail) RES_SET_H_ERRNO(statp, TRY_AGAIN); return (-1); } /*% * Perform a call on res_query on the concatenation of name and domain, * removing a trailing dot from name if domain is NULL. */ int res_nquerydomain(res_state statp, const char *name, const char *domain, int class, int type, /*%< class and type of query */ u_char *answer, /*%< buffer to put answer */ int anslen) /*%< size of answer */ { char nbuf[MAXDNAME]; const char *longname = nbuf; size_t n, d; #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_nquerydomain(%s, %s, %d, %d)\n", name, domain?domain:"<Nil>", class, type); #endif if (domain == NULL) { /* * Check for trailing '.'; * copy without '.' if present. */ n = strlen(name); if (n >= MAXDNAME) { RES_SET_H_ERRNO(statp, NO_RECOVERY); return (-1); } if (n && name[--n] == '.') { strncpy(nbuf, name, n); nbuf[n] = '\0'; } else longname = name; } else { n = strlen(name); d = strlen(domain); if (n + d + 1 >= MAXDNAME) { RES_SET_H_ERRNO(statp, NO_RECOVERY); return (-1); } sprintf(nbuf, "%s.%s", name, domain); } return (res_nquery(statp, longname, class, type, answer, anslen)); } const char * res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { char *file, *cp1, *cp2; char buf[BUFSIZ]; FILE *fp; if (statp->options & RES_NOALIASES) return (NULL); file = getenv("HOSTALIASES"); if (file == NULL || (fp = fopen(file, "re")) == NULL) return (NULL); buf[sizeof(buf) - 1] = '\0'; while (fgets(buf, (int)sizeof(buf), fp)) { for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) ; if (!*cp1) break; *cp1 = '\0'; if (ns_samename(buf, name) == 1) { while (isspace((unsigned char)*++cp1)) ; if (!*cp1) break; for (cp2 = cp1 + 1; *cp2 && !isspace((unsigned char)*cp2); ++cp2) ; *cp2 = '\0'; strncpy(dst, cp1, siz - 1); dst[siz - 1] = '\0'; fclose(fp); return (dst); } } fclose(fp); return (NULL); } /*! \file */
