1*61023Skarels /*- 233736Sbostic * Copyright (c) 1988 Regents of the University of California. 333736Sbostic * All rights reserved. 433736Sbostic * 542627Sbostic * %sccs.include.redist.c% 6*61023Skarels * - 7*61023Skarels * Portions Copyright (c) 1993 by Digital Equipment Corporation. 8*61023Skarels * 9*61023Skarels * Permission to use, copy, modify, and distribute this software for any 10*61023Skarels * purpose with or without fee is hereby granted, provided that the above 11*61023Skarels * copyright notice and this permission notice appear in all copies, and that 12*61023Skarels * the name of Digital Equipment Corporation not be used in advertising or 13*61023Skarels * publicity pertaining to distribution of the document or software without 14*61023Skarels * specific, written prior permission. 15*61023Skarels * 16*61023Skarels * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 17*61023Skarels * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 18*61023Skarels * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 19*61023Skarels * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 20*61023Skarels * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 21*61023Skarels * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 22*61023Skarels * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 23*61023Skarels * SOFTWARE. 24*61023Skarels * - 25*61023Skarels * --Copyright-- 2633736Sbostic */ 2733736Sbostic 2833736Sbostic #if defined(LIBC_SCCS) && !defined(lint) 29*61023Skarels static char sccsid[] = "@(#)res_query.c 5.12 (Berkeley) 06/02/93"; 30*61023Skarels static char rcsid[] = "$Id: res_query.c,v 1.1 1993/06/01 09:42:14 vixie Exp vixie $"; 3133736Sbostic #endif /* LIBC_SCCS and not lint */ 3233736Sbostic 3333736Sbostic #include <sys/param.h> 3433736Sbostic #include <netinet/in.h> 3546604Sbostic #include <arpa/inet.h> 3646604Sbostic #include <arpa/nameser.h> 3733736Sbostic #include <netdb.h> 3846604Sbostic #include <resolv.h> 3933736Sbostic #include <stdio.h> 4046606Sbostic #include <ctype.h> 4133736Sbostic #include <errno.h> 4246604Sbostic #include <stdlib.h> 4342026Sbostic #include <string.h> 4433736Sbostic 4533736Sbostic #if PACKETSZ > 1024 4633736Sbostic #define MAXPACKET PACKETSZ 4733736Sbostic #else 4833736Sbostic #define MAXPACKET 1024 4933736Sbostic #endif 5033736Sbostic 5133736Sbostic int h_errno; 5233736Sbostic 5333736Sbostic /* 5433736Sbostic * Formulate a normal query, send, and await answer. 5533736Sbostic * Returned answer is placed in supplied buffer "answer". 5633736Sbostic * Perform preliminary check of answer, returning success only 5733736Sbostic * if no error is indicated and the answer count is nonzero. 5833736Sbostic * Return the size of the response on success, -1 on error. 5933736Sbostic * Error number is left in h_errno. 6033826Skarels * Caller must parse answer and determine whether it answers the question. 6133736Sbostic */ 6233736Sbostic res_query(name, class, type, answer, anslen) 6333736Sbostic char *name; /* domain name */ 6433736Sbostic int class, type; /* class and type of query */ 6533736Sbostic u_char *answer; /* buffer to put answer */ 6633736Sbostic int anslen; /* size of answer buffer */ 6733736Sbostic { 6833736Sbostic char buf[MAXPACKET]; 6933736Sbostic HEADER *hp; 7033736Sbostic int n; 7133736Sbostic 7233736Sbostic if ((_res.options & RES_INIT) == 0 && res_init() == -1) 7333736Sbostic return (-1); 7433736Sbostic #ifdef DEBUG 7533736Sbostic if (_res.options & RES_DEBUG) 76*61023Skarels printf(";; res_query(%s, %d, %d)\n", name, class, type); 7733736Sbostic #endif 7833736Sbostic n = res_mkquery(QUERY, name, class, type, (char *)NULL, 0, NULL, 7933736Sbostic buf, sizeof(buf)); 8033736Sbostic 8133736Sbostic if (n <= 0) { 8233736Sbostic #ifdef DEBUG 8333736Sbostic if (_res.options & RES_DEBUG) 84*61023Skarels printf(";; res_query: mkquery failed\n"); 8533736Sbostic #endif 8633736Sbostic h_errno = NO_RECOVERY; 8733736Sbostic return (n); 8833736Sbostic } 8946604Sbostic n = res_send(buf, n, (char *)answer, anslen); 9033736Sbostic if (n < 0) { 9133736Sbostic #ifdef DEBUG 9233736Sbostic if (_res.options & RES_DEBUG) 93*61023Skarels printf(";; res_query: send error\n"); 9433736Sbostic #endif 9533736Sbostic h_errno = TRY_AGAIN; 9633736Sbostic return(n); 9733736Sbostic } 9833736Sbostic 9933736Sbostic hp = (HEADER *) answer; 10033736Sbostic if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 10133736Sbostic #ifdef DEBUG 10233736Sbostic if (_res.options & RES_DEBUG) 103*61023Skarels printf(";; rcode = %d, ancount=%d\n", hp->rcode, 10433736Sbostic ntohs(hp->ancount)); 10533736Sbostic #endif 10633736Sbostic switch (hp->rcode) { 10733736Sbostic case NXDOMAIN: 10833826Skarels h_errno = HOST_NOT_FOUND; 10933736Sbostic break; 11033736Sbostic case SERVFAIL: 11133736Sbostic h_errno = TRY_AGAIN; 11233736Sbostic break; 11333736Sbostic case NOERROR: 11433977Skarels h_errno = NO_DATA; 11533736Sbostic break; 11633736Sbostic case FORMERR: 11733736Sbostic case NOTIMP: 11833736Sbostic case REFUSED: 11933826Skarels default: 12033736Sbostic h_errno = NO_RECOVERY; 12133826Skarels break; 12233736Sbostic } 12333736Sbostic return (-1); 12433736Sbostic } 12533736Sbostic return(n); 12633736Sbostic } 12733736Sbostic 12833736Sbostic /* 12933736Sbostic * Formulate a normal query, send, and retrieve answer in supplied buffer. 13033736Sbostic * Return the size of the response on success, -1 on error. 13133736Sbostic * If enabled, implement search rules until answer or unrecoverable failure 13233736Sbostic * is detected. Error number is left in h_errno. 13333736Sbostic * Only useful for queries in the same name hierarchy as the local host 13433736Sbostic * (not, for example, for host address-to-name lookups in domain in-addr.arpa). 13533736Sbostic */ 136*61023Skarels int 13733736Sbostic res_search(name, class, type, answer, anslen) 13833736Sbostic char *name; /* domain name */ 13933736Sbostic int class, type; /* class and type of query */ 14033736Sbostic u_char *answer; /* buffer to put answer */ 14133736Sbostic int anslen; /* size of answer */ 14233736Sbostic { 14333736Sbostic register char *cp, **domain; 14433977Skarels int n, ret, got_nodata = 0; 14547045Sbostic char *__hostalias(); 14633736Sbostic 14733736Sbostic if ((_res.options & RES_INIT) == 0 && res_init() == -1) 14833736Sbostic return (-1); 14933736Sbostic 15033736Sbostic errno = 0; 151*61023Skarels h_errno = HOST_NOT_FOUND; /* default, if we never query */ 15233736Sbostic for (cp = name, n = 0; *cp; cp++) 15333736Sbostic if (*cp == '.') 15433736Sbostic n++; 15547045Sbostic if (n == 0 && (cp = __hostalias(name))) 15633736Sbostic return (res_query(cp, class, type, answer, anslen)); 15733736Sbostic 15835655Skarels /* 15935655Skarels * We do at least one level of search if 16035655Skarels * - there is no dot and RES_DEFNAME is set, or 16135655Skarels * - there is at least one dot, there is no trailing dot, 16235655Skarels * and RES_DNSRCH is set. 16335655Skarels */ 16435655Skarels if ((n == 0 && _res.options & RES_DEFNAMES) || 16535655Skarels (n != 0 && *--cp != '.' && _res.options & RES_DNSRCH)) 16635655Skarels for (domain = _res.dnsrch; *domain; domain++) { 16733736Sbostic ret = res_querydomain(name, *domain, class, type, 16833736Sbostic answer, anslen); 16933736Sbostic if (ret > 0) 17033736Sbostic return (ret); 17133736Sbostic /* 17233736Sbostic * If no server present, give up. 17333736Sbostic * If name isn't found in this domain, 17433736Sbostic * keep trying higher domains in the search list 17533736Sbostic * (if that's enabled). 17633977Skarels * On a NO_DATA error, keep trying, otherwise 17733736Sbostic * a wildcard entry of another type could keep us 17833736Sbostic * from finding this entry higher in the domain. 17935655Skarels * If we get some other error (negative answer or 18035655Skarels * server failure), then stop searching up, 18133736Sbostic * but try the input name below in case it's fully-qualified. 18233736Sbostic */ 18333736Sbostic if (errno == ECONNREFUSED) { 18433736Sbostic h_errno = TRY_AGAIN; 18533736Sbostic return (-1); 18633736Sbostic } 18733977Skarels if (h_errno == NO_DATA) 18833977Skarels got_nodata++; 18933977Skarels if ((h_errno != HOST_NOT_FOUND && h_errno != NO_DATA) || 19033736Sbostic (_res.options & RES_DNSRCH) == 0) 19133736Sbostic break; 19233736Sbostic } 19333736Sbostic /* 19433736Sbostic * If the search/default failed, try the name as fully-qualified, 19533736Sbostic * but only if it contained at least one dot (even trailing). 19635655Skarels * This is purely a heuristic; we assume that any reasonable query 19735655Skarels * about a top-level domain (for servers, SOA, etc) will not use 19835655Skarels * res_search. 19933736Sbostic */ 20035655Skarels if (n && (ret = res_querydomain(name, (char *)NULL, class, type, 20135655Skarels answer, anslen)) > 0) 20235655Skarels return (ret); 20333977Skarels if (got_nodata) 20433977Skarels h_errno = NO_DATA; 20533736Sbostic return (-1); 20633736Sbostic } 20733736Sbostic 20833736Sbostic /* 20933736Sbostic * Perform a call on res_query on the concatenation of name and domain, 21033736Sbostic * removing a trailing dot from name if domain is NULL. 21133736Sbostic */ 21233736Sbostic res_querydomain(name, domain, class, type, answer, anslen) 21333736Sbostic char *name, *domain; 21433736Sbostic int class, type; /* class and type of query */ 21533736Sbostic u_char *answer; /* buffer to put answer */ 21633736Sbostic int anslen; /* size of answer */ 21733736Sbostic { 21833736Sbostic char nbuf[2*MAXDNAME+2]; 21933736Sbostic char *longname = nbuf; 22033736Sbostic int n; 22133736Sbostic 22233977Skarels #ifdef DEBUG 22333977Skarels if (_res.options & RES_DEBUG) 224*61023Skarels printf(";; res_querydomain(%s, %s, %d, %d)\n", 22533977Skarels name, domain, class, type); 22633977Skarels #endif 22733736Sbostic if (domain == NULL) { 22833736Sbostic /* 22933736Sbostic * Check for trailing '.'; 23033736Sbostic * copy without '.' if present. 23133736Sbostic */ 23233736Sbostic n = strlen(name) - 1; 23333736Sbostic if (name[n] == '.' && n < sizeof(nbuf) - 1) { 23433736Sbostic bcopy(name, nbuf, n); 23533736Sbostic nbuf[n] = '\0'; 23633736Sbostic } else 23733736Sbostic longname = name; 23833736Sbostic } else 23933736Sbostic (void)sprintf(nbuf, "%.*s.%.*s", 24033736Sbostic MAXDNAME, name, MAXDNAME, domain); 24133736Sbostic 24233736Sbostic return (res_query(longname, class, type, answer, anslen)); 24333736Sbostic } 24433736Sbostic 24547045Sbostic char * 24647045Sbostic __hostalias(name) 24747045Sbostic register const char *name; 24833736Sbostic { 24933736Sbostic register char *C1, *C2; 25033736Sbostic FILE *fp; 25133736Sbostic char *file, *getenv(), *strcpy(), *strncpy(); 25233736Sbostic char buf[BUFSIZ]; 25333736Sbostic static char abuf[MAXDNAME]; 25433736Sbostic 25533736Sbostic file = getenv("HOSTALIASES"); 25633736Sbostic if (file == NULL || (fp = fopen(file, "r")) == NULL) 25733736Sbostic return (NULL); 25833736Sbostic buf[sizeof(buf) - 1] = '\0'; 25933736Sbostic while (fgets(buf, sizeof(buf), fp)) { 26033736Sbostic for (C1 = buf; *C1 && !isspace(*C1); ++C1); 26133736Sbostic if (!*C1) 26233736Sbostic break; 26333736Sbostic *C1 = '\0'; 26433736Sbostic if (!strcasecmp(buf, name)) { 26533736Sbostic while (isspace(*++C1)); 26633736Sbostic if (!*C1) 26733736Sbostic break; 26833736Sbostic for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2); 26933736Sbostic abuf[sizeof(abuf) - 1] = *C2 = '\0'; 27033736Sbostic (void)strncpy(abuf, C1, sizeof(abuf) - 1); 27133736Sbostic fclose(fp); 27233736Sbostic return (abuf); 27333736Sbostic } 27433736Sbostic } 27533736Sbostic fclose(fp); 27633736Sbostic return (NULL); 27733736Sbostic } 278