/* $OpenBSD: res_send.c,v 1.4 1997/03/13 19:07:41 downsj Exp $ */ /* * ++Copyright++ 1985, 1989, 1993 * - * Copyright (c) 1985, 1989, 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. 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. * - * 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. * - * --Copyright-- */ #if defined(LIBC_SCCS) && !defined(lint) #if 0 static char sccsid[] = "@(#)res_send.c 8.1 (Berkeley) 6/4/93"; static char rcsid[] = "$From: res_send.c,v 8.12 1996/10/08 04:51:06 vixie Exp $"; #else static char rcsid[] = "$OpenBSD: res_send.c,v 1.4 1997/03/13 19:07:41 downsj Exp $"; #endif #endif /* LIBC_SCCS and not lint */ /* change this to "0" * if you talk to a lot * of multi-homed SunOS * ("broken") name servers. */ #define CHECK_SRVR_ADDR 1 /* XXX - should be in options.h */ /* * Send query to name server and wait for reply. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static int s = -1; /* socket used for communications */ static int connected = 0; /* is the socket connected */ static int vc = 0; /* is the socket a virtual ciruit? */ #ifndef FD_SET /* XXX - should be in portability.h */ #define NFDBITS 32 #define FD_SETSIZE 32 #define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS))) #define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS))) #define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS))) #define FD_ZERO(p) bzero((char *)(p), sizeof(*(p))) #endif #define CAN_RECONNECT 1 #ifndef DEBUG # define Dprint(cond, args) /*empty*/ # define DprintQ(cond, args, query, size) /*empty*/ # define Aerror(file, string, error, address) /*empty*/ # define Perror(file, string, error) /*empty*/ #else # define Dprint(cond, args) if (cond) {fprintf args;} else {} # define DprintQ(cond, args, query, size) if (cond) {\ fprintf args;\ __fp_nquery(query, size, stdout);\ } else {} static void Aerror(file, string, error, address) FILE *file; char *string; int error; struct sockaddr_in address; { int save = errno; if (_res.options & RES_DEBUG) { fprintf(file, "res_send: %s ([%s].%u): %s\n", string, inet_ntoa(address.sin_addr), ntohs(address.sin_port), strerror(error)); } errno = save; } static void Perror(file, string, error) FILE *file; char *string; int error; { int save = errno; if (_res.options & RES_DEBUG) { fprintf(file, "res_send: %s: %s\n", string, strerror(error)); } errno = save; } #endif static res_send_qhook Qhook = NULL; static res_send_rhook Rhook = NULL; void res_send_setqhook(hook) res_send_qhook hook; { Qhook = hook; } void res_send_setrhook(hook) res_send_rhook hook; { Rhook = hook; } /* int * res_isourserver(ina) * looks up "ina" in _res.ns_addr_list[] * returns: * 0 : not found * >0 : found * author: * paul vixie, 29may94 */ int res_isourserver(inp) const struct sockaddr_in *inp; { struct sockaddr_in ina; register int ns, ret; ina = *inp; ret = 0; for (ns = 0; ns < _res.nscount; ns++) { register const struct sockaddr_in *srv = &_res.nsaddr_list[ns]; if (srv->sin_family == ina.sin_family && srv->sin_port == ina.sin_port && (srv->sin_addr.s_addr == INADDR_ANY || srv->sin_addr.s_addr == ina.sin_addr.s_addr)) { ret++; break; } } return (ret); } /* int * res_nameinquery(name, type, class, buf, eom) * look for (name,type,class) in the query section of packet (buf,eom) * returns: * -1 : format error * 0 : not found * >0 : found * author: * paul vixie, 29may94 */ int res_nameinquery(name, type, class, buf, eom) const char *name; register int type, class; const u_char *buf, *eom; { register const u_char *cp = buf + HFIXEDSZ; int qdcount = ntohs(((HEADER*)buf)->qdcount); while (qdcount-- > 0) { char tname[MAXDNAME+1]; register int n, ttype, tclass; n = dn_expand(buf, eom, cp, tname, sizeof tname); if (n < 0) return (-1); cp += n; ttype = _getshort(cp); cp += INT16SZ; tclass = _getshort(cp); cp += INT16SZ; if (ttype == type && tclass == class && strcasecmp(tname, name) == 0) return (1); } return (0); } /* int * res_queriesmatch(buf1, eom1, buf2, eom2) * is there a 1:1 mapping of (name,type,class) * in (buf1,eom1) and (buf2,eom2)? * returns: * -1 : format error * 0 : not a 1:1 mapping * >0 : is a 1:1 mapping * author: * paul vixie, 29may94 */ int res_queriesmatch(buf1, eom1, buf2, eom2) const u_char *buf1, *eom1; const u_char *buf2, *eom2; { register const u_char *cp = buf1 + HFIXEDSZ; int qdcount = ntohs(((HEADER*)buf1)->qdcount); if (qdcount != ntohs(((HEADER*)buf2)->qdcount)) return (0); while (qdcount-- > 0) { char tname[MAXDNAME+1]; register int n, ttype, tclass; n = dn_expand(buf1, eom1, cp, tname, sizeof tname); if (n < 0) return (-1); cp += n; ttype = _getshort(cp); cp += INT16SZ; tclass = _getshort(cp); cp += INT16SZ; if (!res_nameinquery(tname, ttype, tclass, buf2, eom2)) return (0); } return (1); } int res_send(buf, buflen, ans, anssiz) const u_char *buf; int buflen; u_char *ans; int anssiz; { HEADER *hp = (HEADER *) buf; HEADER *anhp = (HEADER *) ans; int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns; register int n; u_int badns; /* XXX NSMAX can't exceed #/bits in this var */ if ((_res.options & RES_INIT) == 0 && res_init() == -1) { /* errno should have been set by res_init() in this case. */ return (-1); } DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY), (stdout, ";; res_send()\n"), buf, buflen); v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ; gotsomewhere = 0; connreset = 0; terrno = ETIMEDOUT; badns = 0; /* * Send request, RETRY times, or until successful */ for (try = 0; try < _res.retry; try++) { for (ns = 0; ns < _res.nscount; ns++) { struct sockaddr_in *nsap = &_res.nsaddr_list[ns]; same_ns: if (badns & (1 << ns)) { res_close(); goto next_ns; } if (Qhook) { int done = 0, loops = 0; do { res_sendhookact act; act = (*Qhook)(&nsap, &buf, &buflen, ans, anssiz, &resplen); switch (act) { case res_goahead: done = 1; break; case res_nextns: res_close(); goto next_ns; case res_done: return (resplen); case res_modified: /* give the hook another try */ if (++loops < 42) /*doug adams*/ break; /*FALLTHROUGH*/ case res_error: /*FALLTHROUGH*/ default: return (-1); } } while (!done); } Dprint(_res.options & RES_DEBUG, (stdout, ";; Querying server (# %d) address = %s\n", ns + 1, inet_ntoa(nsap->sin_addr))); if (v_circuit) { int truncated; struct iovec iov[2]; u_short len; u_char *cp; /* * Use virtual circuit; * at most one attempt per server. */ try = _res.retry; truncated = 0; if ((s < 0) || (!vc)) { if (s >= 0) res_close(); s = socket(PF_INET, SOCK_STREAM, 0); if (s < 0) { terrno = errno; Perror(stderr, "socket(vc)", errno); return (-1); } errno = 0; if (connect(s, (struct sockaddr *)nsap, sizeof(struct sockaddr)) < 0) { terrno = errno; Aerror(stderr, "connect/vc", errno, *nsap); badns |= (1 << ns); res_close(); goto next_ns; } vc = 1; } /* * Send length & message */ putshort((u_short)buflen, (u_char*)&len); iov[0].iov_base = (caddr_t)&len; iov[0].iov_len = INT16SZ; iov[1].iov_base = (caddr_t)buf; iov[1].iov_len = buflen; if (writev(s, iov, 2) != (INT16SZ + buflen)) { terrno = errno; Perror(stderr, "write failed", errno); badns |= (1 << ns); res_close(); goto next_ns; } /* * Receive length & response */ read_len: cp = ans; len = INT16SZ; while ((n = read(s, (char *)cp, (int)len)) > 0) { cp += n; if ((len -= n) <= 0) break; } if (n <= 0) { terrno = errno; Perror(stderr, "read failed", errno); res_close(); /* * A long running process might get its TCP * connection reset if the remote server was * restarted. Requery the server instead of * trying a new one. When there is only one * server, this means that a query might work * instead of failing. We only allow one reset * per query to prevent looping. */ if (terrno == ECONNRESET && !connreset) { connreset = 1; res_close(); goto same_ns; } res_close(); goto next_ns; } resplen = _getshort(ans); if (resplen > anssiz) { Dprint(_res.options & RES_DEBUG, (stdout, ";; response truncated\n") ); truncated = 1; len = anssiz; } else len = resplen; cp = ans; while (len != 0 && (n = read(s, (char *)cp, (int)len)) > 0) { cp += n; len -= n; } if (n <= 0) { terrno = errno; Perror(stderr, "read(vc)", errno); res_close(); goto next_ns; } if (truncated) { /* * Flush rest of answer * so connection stays in synch. */ anhp->tc = 1; len = resplen - anssiz; while (len != 0) { char junk[PACKETSZ]; n = (len > sizeof(junk) ? sizeof(junk) : len); if ((n = read(s, junk, n)) > 0) len -= n; else break; } } /* * The calling applicating has bailed out of * a previous call and failed to arrange to have * the circuit closed or the server has got * itself confused. Anyway drop the packet and * wait for the correct one. */ if (hp->id != anhp->id) { DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_REPLY), (stdout, ";; old answer (unexpected):\n"), ans, (resplen>anssiz)?anssiz:resplen); goto read_len; } } else { /* * Use datagrams. */ struct timeval timeout; fd_set dsmask; struct sockaddr_in from; int fromlen; if ((s < 0) || vc) { if (vc) res_close(); s = socket(PF_INET, SOCK_DGRAM, 0); if (s < 0) { #if !CAN_RECONNECT bad_dg_sock: #endif terrno = errno; Perror(stderr, "socket(dg)", errno); return (-1); } connected = 0; } /* * On a 4.3BSD+ machine (client and server, * actually), sending to a nameserver datagram * port with no nameserver will cause an * ICMP port unreachable message to be returned. * If our datagram socket is "connected" to the * server, we get an ECONNREFUSED error on the next * socket operation, and select returns if the * error message is received. We can thus detect * the absence of a nameserver without timing out. * If we have sent queries to at least two servers, * however, we don't want to remain connected, * as we wish to receive answers from the first * server to respond. */ if (_res.nscount == 1 || (try == 0 && ns == 0)) { /* * Connect only if we are sure we won't * receive a response from another server. */ if (!connected) { if (connect(s, (struct sockaddr *)nsap, sizeof(struct sockaddr) ) < 0) { Aerror(stderr, "connect(dg)", errno, *nsap); badns |= (1 << ns); res_close(); goto next_ns; } connected = 1; } if (send(s, (char*)buf, buflen, 0) != buflen) { Perror(stderr, "send", errno); badns |= (1 << ns); res_close(); goto next_ns; } } else { /* * Disconnect if we want to listen * for responses from more than one server. */ if (connected) { #if CAN_RECONNECT struct sockaddr_in no_addr; no_addr.sin_family = AF_INET; no_addr.sin_addr.s_addr = INADDR_ANY; no_addr.sin_port = 0; (void) connect(s, (struct sockaddr *) &no_addr, sizeof(no_addr)); #else int s1 = socket(PF_INET, SOCK_DGRAM,0); if (s1 < 0) goto bad_dg_sock; (void) dup2(s1, s); (void) close(s1); Dprint(_res.options & RES_DEBUG, (stdout, ";; new DG socket\n")) #endif connected = 0; errno = 0; } if (sendto(s, (char*)buf, buflen, 0, (struct sockaddr *)nsap, sizeof(struct sockaddr)) != buflen) { Aerror(stderr, "sendto", errno, *nsap); badns |= (1 << ns); res_close(); goto next_ns; } } /* * Wait for reply */ timeout.tv_sec = (_res.retrans << try); if (try > 0) timeout.tv_sec /= _res.nscount; if ((long) timeout.tv_sec <= 0) timeout.tv_sec = 1; timeout.tv_usec = 0; wait: FD_ZERO(&dsmask); FD_SET(s, &dsmask); n = select(s+1, &dsmask, (fd_set *)NULL, (fd_set *)NULL, &timeout); if (n < 0) { if (errno == EINTR) goto wait; Perror(stderr, "select", errno); res_close(); goto next_ns; } if (n == 0) { /* * timeout */ Dprint(_res.options & RES_DEBUG, (stdout, ";; timeout\n")); gotsomewhere = 1; res_close(); goto next_ns; } errno = 0; fromlen = sizeof(struct sockaddr_in); resplen = recvfrom(s, (char*)ans, anssiz, 0, (struct sockaddr *)&from, &fromlen); if (resplen <= 0) { Perror(stderr, "recvfrom", errno); res_close(); goto next_ns; } gotsomewhere = 1; if (hp->id != anhp->id) { /* * response from old query, ignore it. * XXX - potential security hazard could * be detected here. */ DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_REPLY), (stdout, ";; old answer:\n"), ans, (resplen>anssiz)?anssiz:resplen); goto wait; } #if CHECK_SRVR_ADDR if (!(_res.options & RES_INSECURE1) && !res_isourserver(&from)) { /* * response from wrong server? ignore it. * XXX - potential security hazard could * be detected here. */ DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_REPLY), (stdout, ";; not our server:\n"), ans, (resplen>anssiz)?anssiz:resplen); goto wait; } #endif if (!(_res.options & RES_INSECURE2) && !res_queriesmatch(buf, buf + buflen, ans, ans + anssiz)) { /* * response contains wrong query? ignore it. * XXX - potential security hazard could * be detected here. */ DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_REPLY), (stdout, ";; wrong query name:\n"), ans, (resplen>anssiz)?anssiz:resplen); goto wait; } if (anhp->rcode == SERVFAIL || anhp->rcode == NOTIMP || anhp->rcode == REFUSED) { DprintQ(_res.options & RES_DEBUG, (stdout, "server rejected query:\n"), ans, (resplen>anssiz)?anssiz:resplen); badns |= (1 << ns); res_close(); /* don't retry if called from dig */ if (!_res.pfcode) goto next_ns; } if (!(_res.options & RES_IGNTC) && anhp->tc) { /* * get rest of answer; * use TCP with same server. */ Dprint(_res.options & RES_DEBUG, (stdout, ";; truncated answer\n")); v_circuit = 1; res_close(); goto same_ns; } } /*if vc/dg*/ Dprint((_res.options & RES_DEBUG) || ((_res.pfcode & RES_PRF_REPLY) && (_res.pfcode & RES_PRF_HEAD1)), (stdout, ";; got answer:\n")); DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_REPLY), (stdout, ""), ans, (resplen>anssiz)?anssiz:resplen); /* * If using virtual circuits, we assume that the first server * is preferred over the rest (i.e. it is on the local * machine) and only keep that one open. * If we have temporarily opened a virtual circuit, * or if we haven't been asked to keep a socket open, * close the socket. */ if ((v_circuit && (!(_res.options & RES_USEVC) || ns != 0)) || !(_res.options & RES_STAYOPEN)) { res_close(); } if (Rhook) { int done = 0, loops = 0; do { res_sendhookact act; act = (*Rhook)(nsap, buf, buflen, ans, anssiz, &resplen); switch (act) { case res_goahead: case res_done: done = 1; break; case res_nextns: res_close(); goto next_ns; case res_modified: /* give the hook another try */ if (++loops < 42) /*doug adams*/ break; /*FALLTHROUGH*/ case res_error: /*FALLTHROUGH*/ default: return (-1); } } while (!done); } return (resplen); next_ns: ; } /*foreach ns*/ } /*foreach retry*/ res_close(); if (!v_circuit) if (!gotsomewhere) errno = ECONNREFUSED; /* no nameservers found */ else errno = ETIMEDOUT; /* no answer obtained */ else errno = terrno; return (-1); } /* * This routine is for closing the socket if a virtual circuit is used and * the program wants to close it. This provides support for endhostent() * which expects to close the socket. * * This routine is not expected to be user visible. */ void res_close() { if (s >= 0) { (void) close(s); s = -1; connected = 0; vc = 0; } }