/* * 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. * 4. 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. */ /* * Portions Copyright (c) 1996-1999 by Internet Software Consortium. * * 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. * * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE * CONSORTIUM 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[] = "$BINDId: res_query.c,v 8.20 2000/02/29 05:39:12 vixie Exp $"; #endif /* LIBC_SCCS and not lint */ #include #include #include #include #include #include #include #include #include #include #include #include #include /* Options. Leave them on. */ /* #undef DEBUG */ #if PACKETSZ > 65536 #define MAXPACKET PACKETSZ #else #define MAXPACKET 65536 #endif #define QUERYSIZE (HFIXEDSZ + QFIXEDSZ + MAXCDNAME + 1) static int __libc_res_nquerydomain(res_state statp, const char *name, const char *domain, int class, int type, u_char *answer, int anslen, u_char **answerp, u_char **answerp2, int *nanswerp2, int *resplen2); /* * 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 __libc_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 **answerp, /* if buffer needs to be enlarged */ u_char **answerp2, int *nanswerp2, int *resplen2) { HEADER *hp = (HEADER *) answer; int n, use_malloc = 0; u_int oflags = statp->_flags; size_t bufsize = (type == T_UNSPEC ? 2 : 1) * QUERYSIZE; u_char *buf = alloca (bufsize); u_char *query1 = buf; int nquery1 = -1; u_char *query2 = NULL; int nquery2 = 0; again: hp->rcode = NOERROR; /* default */ #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query(%s, %d, %d)\n", name, class, type); #endif if (type == T_UNSPEC) { n = res_nmkquery(statp, QUERY, name, class, T_A, NULL, 0, NULL, query1, bufsize); if (n > 0) { if ((oflags & RES_F_EDNS0ERR) == 0 && (statp->options & RES_USE_EDNS0) != 0) { n = __res_nopt(statp, n, query1, bufsize, anslen / 2); if (n < 0) goto unspec_nomem; } nquery1 = n; /* Align the buffer. */ int npad = ((nquery1 + __alignof__ (HEADER) - 1) & ~(__alignof__ (HEADER) - 1)) - nquery1; if (n > bufsize - npad) { n = -1; goto unspec_nomem; } int nused = n + npad; query2 = buf + nused; n = res_nmkquery(statp, QUERY, name, class, T_AAAA, NULL, 0, NULL, query2, bufsize - nused); if (n > 0 && (oflags & RES_F_EDNS0ERR) == 0 && (statp->options & RES_USE_EDNS0) != 0) n = __res_nopt(statp, n, query2, bufsize - nused - n, anslen / 2); nquery2 = n; } unspec_nomem:; } else { n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, query1, bufsize); if (n > 0 && (oflags & RES_F_EDNS0ERR) == 0 && (statp->options & RES_USE_EDNS0) != 0) n = __res_nopt(statp, n, query1, bufsize, anslen); nquery1 = n; } if (__builtin_expect (n <= 0, 0) && !use_malloc) { /* Retry just in case res_nmkquery failed because of too short buffer. Shouldn't happen. */ bufsize = (type == T_UNSPEC ? 2 : 1) * MAXPACKET; buf = malloc (bufsize); if (buf != NULL) { query1 = buf; use_malloc = 1; goto again; } } if (__builtin_expect (n <= 0, 0)) { /* If the query choked with EDNS0, retry without EDNS0. */ if ((statp->options & RES_USE_EDNS0) != 0 && ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { statp->_flags |= RES_F_EDNS0ERR; #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_nquery: retry without EDNS0\n"); #endif goto again; } #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query: mkquery failed\n"); #endif RES_SET_H_ERRNO(statp, NO_RECOVERY); if (use_malloc) free (buf); return (n); } assert (answerp == NULL || (void *) *answerp == (void *) answer); n = __libc_res_nsend(statp, query1, nquery1, query2, nquery2, answer, anslen, answerp, answerp2, nanswerp2, resplen2); if (use_malloc) free (buf); if (n < 0) { #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query: send error\n"); #endif RES_SET_H_ERRNO(statp, TRY_AGAIN); return (n); } if (answerp != NULL) /* __libc_res_nsend might have reallocated the buffer. */ hp = (HEADER *) *answerp; /* We simplify the following tests by assigning HP to HP2. It is easy to verify that this is the same as ignoring all tests of HP2. */ HEADER *hp2 = answerp2 ? (HEADER *) *answerp2 : hp; if (n < (int) sizeof (HEADER) && answerp2 != NULL && *resplen2 > (int) sizeof (HEADER)) { /* Special case of partial answer. */ assert (hp != hp2); hp = hp2; } else if (answerp2 != NULL && *resplen2 < (int) sizeof (HEADER) && n > (int) sizeof (HEADER)) { /* Special case of partial answer. */ assert (hp != hp2); hp2 = hp; } if ((hp->rcode != NOERROR || ntohs(hp->ancount) == 0) && (hp2->rcode != NOERROR || ntohs(hp2->ancount) == 0)) { #ifdef DEBUG if (statp->options & RES_DEBUG) { printf(";; rcode = %d, ancount=%d\n", hp->rcode, ntohs(hp->ancount)); if (hp != hp2) printf(";; rcode2 = %d, ancount2=%d\n", hp2->rcode, ntohs(hp2->ancount)); } #endif switch (hp->rcode == NOERROR ? hp2->rcode : hp->rcode) { case NXDOMAIN: if ((hp->rcode == NOERROR && ntohs (hp->ancount) != 0) || (hp2->rcode == NOERROR && ntohs (hp2->ancount) != 0)) goto success; RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); break; case SERVFAIL: RES_SET_H_ERRNO(statp, TRY_AGAIN); break; case NOERROR: if (ntohs (hp->ancount) != 0 || ntohs (hp2->ancount) != 0) goto success; 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); } success: return (n); } libresolv_hidden_def (__libc_res_nquery) 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 */ { return __libc_res_nquery(statp, name, class, type, answer, anslen, NULL, NULL, NULL, NULL); } libresolv_hidden_def (res_nquery) /* * 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 __libc_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 */ u_char **answerp, u_char **answerp2, int *nanswerp2, int *resplen2) { const char *cp, * const *domain; HEADER *hp = (HEADER *) 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; __set_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 (__libc_res_nquery(statp, cp, class, type, answer, anslen, answerp, answerp2, nanswerp2, resplen2)); #ifdef DEBUG if (statp->options & RES_DEBUG) printf("dots=%d, statp->ndots=%d, trailing_dot=%d, name=%s\n", (int)dots,(int)statp->ndots,(int)trailing_dot,name); #endif /* * 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 = __libc_res_nquerydomain(statp, name, NULL, class, type, answer, anslen, answerp, answerp2, nanswerp2, resplen2); if (ret > 0 || trailing_dot) return (ret); saved_herrno = h_errno; tried_as_is++; if (answerp && *answerp != answer) { answer = *answerp; anslen = MAXPACKET; } if (answerp2 && (*answerp2 < answer || *answerp2 >= answer + anslen)) { free (*answerp2); *answerp2 = NULL; } } /* * 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) != 0) || (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) { int done = 0; for (domain = (const char * const *)statp->dnsrch; *domain && !done; domain++) { if (domain[0][0] == '\0' || (domain[0][0] == '.' && domain[0][1] == '\0')) root_on_list++; ret = __libc_res_nquerydomain(statp, name, *domain, class, type, answer, anslen, answerp, answerp2, nanswerp2, resplen2); if (ret > 0) return (ret); if (answerp && *answerp != answer) { answer = *answerp; anslen = MAXPACKET; } if (answerp2 && (*answerp2 < answer || *answerp2 >= answer + anslen)) { free (*answerp2); *answerp2 = NULL; } /* * 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) == 0) done++; } } /* * If the name has any dots at all, and no earlier 'as-is' query * for the name, and "." is not on the search list, then try an as-is * query now. */ if (dots && !(tried_as_is || root_on_list)) { ret = __libc_res_nquerydomain(statp, name, NULL, class, type, answer, anslen, answerp, answerp2, nanswerp2, resplen2); 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 (answerp2 && (*answerp2 < answer || *answerp2 >= answer + anslen)) { free (*answerp2); *answerp2 = NULL; } 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); } libresolv_hidden_def (__libc_res_nsearch) 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 */ { return __libc_res_nsearch(statp, name, class, type, answer, anslen, NULL, NULL, NULL, NULL); } libresolv_hidden_def (res_nsearch) /* * Perform a call on res_query on the concatenation of name and domain, * removing a trailing dot from name if domain is NULL. */ static int __libc_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 */ u_char **answerp, u_char **answerp2, int *nanswerp2, int *resplen2) { char nbuf[MAXDNAME]; const char *longname = nbuf; int n, d; #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_nquerydomain(%s, %s, %d, %d)\n", name, domain?domain:"", 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); } n--; if (n >= 0 && 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 (__libc_res_nquery(statp, longname, class, type, answer, anslen, answerp, answerp2, nanswerp2, resplen2)); } 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 */ { return __libc_res_nquerydomain(statp, name, domain, class, type, answer, anslen, NULL, NULL, NULL, NULL); } libresolv_hidden_def (res_nquerydomain) 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, "r")) == NULL) return (NULL); setbuf(fp, NULL); buf[sizeof(buf) - 1] = '\0'; while (fgets(buf, sizeof(buf), fp)) { for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1) ; if (!*cp1) break; *cp1 = '\0'; if (ns_samename(buf, name) == 1) { while (isspace(*++cp1)) ; if (!*cp1) break; for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2) ; *cp2 = '\0'; strncpy(dst, cp1, siz - 1); dst[siz - 1] = '\0'; fclose(fp); return (dst); } } fclose(fp); return (NULL); } libresolv_hidden_def (res_hostalias)