/* * Copyright (c) 1988 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 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. */ #if defined(LIBC_SCCS) && !defined(lint) static char sccsid[] = "@(#)res_query.c 5.11 (Berkeley) 3/6/91"; #endif /* LIBC_SCCS and not lint */ #define KERNEL #include "ixnet.h" #include #include #include #include #include #include #include #include #include #include #include "utils.h" #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_query(char *name, int class, int type, u_char *answer, int anslen) { char buf[MAXPACKET]; HEADER *hp; int n; if ((_res.options & RES_INIT) == 0 && res_init() == -1) return (-1); #ifdef DEBUG if (_res.options & RES_DEBUG) printf("res_query(%s, %d, %d)\n", name, class, type); #endif n = res_mkquery(QUERY, name, class, type, (char *)NULL, 0, NULL, buf, sizeof(buf)); if (n <= 0) { #ifdef DEBUG if (_res.options & RES_DEBUG) printf("res_query: mkquery failed\n"); #endif h_errno = NO_RECOVERY; return (n); } n = res_send(buf, n, (char *)answer, anslen); if (n < 0) { #ifdef DEBUG if (_res.options & RES_DEBUG) printf("res_query: send error\n"); #endif h_errno = TRY_AGAIN; return(n); } hp = (HEADER *) answer; if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { #ifdef DEBUG if (_res.options & RES_DEBUG) printf("rcode = %d, ancount=%d\n", hp->rcode, ntohs(hp->ancount)); #endif switch (hp->rcode) { case NXDOMAIN: h_errno = HOST_NOT_FOUND; break; case SERVFAIL: h_errno = TRY_AGAIN; break; case NOERROR: h_errno = NO_DATA; break; case FORMERR: case NOTIMP: case REFUSED: default: h_errno = 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 number is left in h_errno. * Only useful for queries in the same name hierarchy as the local host * (not, for example, for host address-to-name lookups in domain in-addr.arpa). */ int res_search(char *name, int class, int type, u_char *answer, int anslen) { register char *cp, **domain; int n, ret, got_nodata = 0; char *__hostalias(); if ((_res.options & RES_INIT) == 0 && res_init() == -1) return (-1); errno = 0; h_errno = HOST_NOT_FOUND; /* default, if we never query */ for (cp = name, n = 0; *cp; cp++) if (*cp == '.') n++; if (n == 0 && (cp = __hostalias(name))) return (res_query(cp, class, type, answer, anslen)); /* * 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 ((n == 0 && _res.options & RES_DEFNAMES) || (n != 0 && *--cp != '.' && _res.options & RES_DNSRCH)) for (domain = _res.dnsrch; *domain; domain++) { ret = res_querydomain(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) { h_errno = TRY_AGAIN; return (-1); } if (h_errno == NO_DATA) got_nodata++; if ((h_errno != HOST_NOT_FOUND && h_errno != NO_DATA) || (_res.options & RES_DNSRCH) == 0) break; } /* * If the search/default failed, try the name as fully-qualified, * but only if it contained at least one dot (even trailing). * This is purely a heuristic; we assume that any reasonable query * about a top-level domain (for servers, SOA, etc) will not use * res_search. */ if (n && (ret = res_querydomain(name, (char *)NULL, class, type, answer, anslen)) > 0) return (ret); if (got_nodata) h_errno = NO_DATA; 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_querydomain(char *name, char *domain, int class, int type, u_char *answer, int anslen) { char nbuf[2*MAXDNAME+2]; char *longname = nbuf; int n; #ifdef DEBUG if (_res.options & RES_DEBUG) printf("res_querydomain(%s, %s, %d, %d)\n", name, domain, class, type); #endif if (domain == NULL) { /* * Check for trailing '.'; * copy without '.' if present. */ n = strlen(name) - 1; if (name[n] == '.' && n < sizeof(nbuf) - 1) { bcopy(name, nbuf, n); nbuf[n] = '\0'; } else longname = name; } else (void)sprintf(nbuf, "%.*s.%.*s", MAXDNAME, name, MAXDNAME, domain); return (res_query(longname, class, type, answer, anslen)); } char * __hostalias(const char *name) { register char *C1, *C2; FILE *fp; char *file, *getenv(), *strcpy(), *strncpy(); char buf[BUFSIZ]; static char abuf[MAXDNAME]; file = getenv("HOSTALIASES"); if (file == NULL || (fp = fopen(file, "r")) == NULL) return (NULL); buf[sizeof(buf) - 1] = '\0'; while (fgets(buf, sizeof(buf), fp)) { for (C1 = buf; *C1 && !isspace(*C1); ++C1); if (!*C1) break; *C1 = '\0'; if (!strcasecmp(buf, name)) { while (isspace(*++C1)) ; if (!*C1) break; for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2) ; abuf[sizeof(abuf) - 1] = *C2 = '\0'; (void)strncpy(abuf, C1, sizeof(abuf) - 1); fclose(fp); return (abuf); } } fclose(fp); return (NULL); }