1*7c478bd9Sstevel@tonic-gate /* 2*7c478bd9Sstevel@tonic-gate * CDDL HEADER START 3*7c478bd9Sstevel@tonic-gate * 4*7c478bd9Sstevel@tonic-gate * The contents of this file are subject to the terms of the 5*7c478bd9Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only 6*7c478bd9Sstevel@tonic-gate * (the "License"). You may not use this file except in compliance 7*7c478bd9Sstevel@tonic-gate * with the License. 8*7c478bd9Sstevel@tonic-gate * 9*7c478bd9Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10*7c478bd9Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing. 11*7c478bd9Sstevel@tonic-gate * See the License for the specific language governing permissions 12*7c478bd9Sstevel@tonic-gate * and limitations under the License. 13*7c478bd9Sstevel@tonic-gate * 14*7c478bd9Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each 15*7c478bd9Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16*7c478bd9Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the 17*7c478bd9Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying 18*7c478bd9Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner] 19*7c478bd9Sstevel@tonic-gate * 20*7c478bd9Sstevel@tonic-gate * CDDL HEADER END 21*7c478bd9Sstevel@tonic-gate */ 22*7c478bd9Sstevel@tonic-gate /* 23*7c478bd9Sstevel@tonic-gate * Copyright 2003 Sun Microsystems, Inc. All rights reserved. 24*7c478bd9Sstevel@tonic-gate * Use is subject to license terms. 25*7c478bd9Sstevel@tonic-gate */ 26*7c478bd9Sstevel@tonic-gate 27*7c478bd9Sstevel@tonic-gate /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 28*7c478bd9Sstevel@tonic-gate /* All Rights Reserved */ 29*7c478bd9Sstevel@tonic-gate 30*7c478bd9Sstevel@tonic-gate /* 31*7c478bd9Sstevel@tonic-gate * University Copyright- Copyright (c) 1982, 1986, 1988 32*7c478bd9Sstevel@tonic-gate * The Regents of the University of California 33*7c478bd9Sstevel@tonic-gate * All Rights Reserved 34*7c478bd9Sstevel@tonic-gate * 35*7c478bd9Sstevel@tonic-gate * University Acknowledgment- Portions of this document are derived from 36*7c478bd9Sstevel@tonic-gate * software developed by the University of California, Berkeley, and its 37*7c478bd9Sstevel@tonic-gate * contributors. 38*7c478bd9Sstevel@tonic-gate */ 39*7c478bd9Sstevel@tonic-gate 40*7c478bd9Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" 41*7c478bd9Sstevel@tonic-gate 42*7c478bd9Sstevel@tonic-gate /* 43*7c478bd9Sstevel@tonic-gate * Send query to name server and wait for reply. 44*7c478bd9Sstevel@tonic-gate */ 45*7c478bd9Sstevel@tonic-gate 46*7c478bd9Sstevel@tonic-gate #include "synonyms.h" 47*7c478bd9Sstevel@tonic-gate 48*7c478bd9Sstevel@tonic-gate #include <sys/param.h> 49*7c478bd9Sstevel@tonic-gate #include <sys/time.h> 50*7c478bd9Sstevel@tonic-gate #include <sys/socket.h> 51*7c478bd9Sstevel@tonic-gate #include <sys/uio.h> 52*7c478bd9Sstevel@tonic-gate #include <sys/stat.h> 53*7c478bd9Sstevel@tonic-gate #include <netinet/in.h> 54*7c478bd9Sstevel@tonic-gate #include <stdio.h> 55*7c478bd9Sstevel@tonic-gate #include <errno.h> 56*7c478bd9Sstevel@tonic-gate #include <arpa/nameser.h> 57*7c478bd9Sstevel@tonic-gate #include <resolv.h> 58*7c478bd9Sstevel@tonic-gate 59*7c478bd9Sstevel@tonic-gate 60*7c478bd9Sstevel@tonic-gate static int s = -1; /* socket used for communications */ 61*7c478bd9Sstevel@tonic-gate static struct sockaddr no_addr; 62*7c478bd9Sstevel@tonic-gate 63*7c478bd9Sstevel@tonic-gate 64*7c478bd9Sstevel@tonic-gate #ifndef FD_SET 65*7c478bd9Sstevel@tonic-gate #define NFDBITS 32 66*7c478bd9Sstevel@tonic-gate #define FD_SETSIZE 32 67*7c478bd9Sstevel@tonic-gate #define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS))) 68*7c478bd9Sstevel@tonic-gate #define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS))) 69*7c478bd9Sstevel@tonic-gate #define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS))) 70*7c478bd9Sstevel@tonic-gate #ifdef SYSV 71*7c478bd9Sstevel@tonic-gate #define FD_ZERO(p) memset((void *)(p), 0, sizeof (*(p))) 72*7c478bd9Sstevel@tonic-gate #else 73*7c478bd9Sstevel@tonic-gate #define FD_ZERO(p) bzero((char *)(p), sizeof (*(p))) 74*7c478bd9Sstevel@tonic-gate #endif 75*7c478bd9Sstevel@tonic-gate #endif 76*7c478bd9Sstevel@tonic-gate 77*7c478bd9Sstevel@tonic-gate /* 78*7c478bd9Sstevel@tonic-gate * 1247019: Kludge to time out quickly if there is no /etc/resolv.conf 79*7c478bd9Sstevel@tonic-gate * and a TCP connection to the local DNS server fails. 80*7c478bd9Sstevel@tonic-gate */ 81*7c478bd9Sstevel@tonic-gate 82*7c478bd9Sstevel@tonic-gate static int _confcheck() 83*7c478bd9Sstevel@tonic-gate { 84*7c478bd9Sstevel@tonic-gate int ns; 85*7c478bd9Sstevel@tonic-gate struct stat rc_stat; 86*7c478bd9Sstevel@tonic-gate struct sockaddr_in ns_sin; 87*7c478bd9Sstevel@tonic-gate 88*7c478bd9Sstevel@tonic-gate 89*7c478bd9Sstevel@tonic-gate /* First, we check to see if /etc/resolv.conf exists. 90*7c478bd9Sstevel@tonic-gate * If it doesn't, then localhost is mostlikely to be 91*7c478bd9Sstevel@tonic-gate * the nameserver. 92*7c478bd9Sstevel@tonic-gate */ 93*7c478bd9Sstevel@tonic-gate if (stat(_PATH_RESCONF, &rc_stat) == -1 && errno == ENOENT) { 94*7c478bd9Sstevel@tonic-gate 95*7c478bd9Sstevel@tonic-gate /* Next, we check to see if _res.nsaddr is set to loopback. 96*7c478bd9Sstevel@tonic-gate * If it isn't, it has been altered by the application 97*7c478bd9Sstevel@tonic-gate * explicitly and we then want to bail with success. 98*7c478bd9Sstevel@tonic-gate */ 99*7c478bd9Sstevel@tonic-gate if (_res.nsaddr.sin_addr.S_un.S_addr == htonl(INADDR_LOOPBACK)) { 100*7c478bd9Sstevel@tonic-gate 101*7c478bd9Sstevel@tonic-gate /* Lastly, we try to connect to the TCP port of the 102*7c478bd9Sstevel@tonic-gate * nameserver. If this fails, then we know that 103*7c478bd9Sstevel@tonic-gate * DNS is misconfigured and we can quickly exit. 104*7c478bd9Sstevel@tonic-gate */ 105*7c478bd9Sstevel@tonic-gate ns = socket(AF_INET, SOCK_STREAM, 0); 106*7c478bd9Sstevel@tonic-gate IN_SET_LOOPBACK_ADDR(&ns_sin); 107*7c478bd9Sstevel@tonic-gate ns_sin.sin_port = htons(NAMESERVER_PORT); 108*7c478bd9Sstevel@tonic-gate if (connect(ns, (struct sockaddr *) &ns_sin, 109*7c478bd9Sstevel@tonic-gate sizeof ns_sin) == -1) { 110*7c478bd9Sstevel@tonic-gate close(ns); 111*7c478bd9Sstevel@tonic-gate return(-1); 112*7c478bd9Sstevel@tonic-gate } 113*7c478bd9Sstevel@tonic-gate else { 114*7c478bd9Sstevel@tonic-gate close(ns); 115*7c478bd9Sstevel@tonic-gate return(0); 116*7c478bd9Sstevel@tonic-gate } 117*7c478bd9Sstevel@tonic-gate } 118*7c478bd9Sstevel@tonic-gate 119*7c478bd9Sstevel@tonic-gate return(0); 120*7c478bd9Sstevel@tonic-gate } 121*7c478bd9Sstevel@tonic-gate 122*7c478bd9Sstevel@tonic-gate return (0); 123*7c478bd9Sstevel@tonic-gate } 124*7c478bd9Sstevel@tonic-gate 125*7c478bd9Sstevel@tonic-gate res_send(buf, buflen, answer, anslen) 126*7c478bd9Sstevel@tonic-gate char *buf; 127*7c478bd9Sstevel@tonic-gate int buflen; 128*7c478bd9Sstevel@tonic-gate char *answer; 129*7c478bd9Sstevel@tonic-gate int anslen; 130*7c478bd9Sstevel@tonic-gate { 131*7c478bd9Sstevel@tonic-gate register int n; 132*7c478bd9Sstevel@tonic-gate int try, v_circuit, resplen, ns; 133*7c478bd9Sstevel@tonic-gate int gotsomewhere = 0, connected = 0; 134*7c478bd9Sstevel@tonic-gate int connreset = 0; 135*7c478bd9Sstevel@tonic-gate u_short id, len; 136*7c478bd9Sstevel@tonic-gate char *cp; 137*7c478bd9Sstevel@tonic-gate fd_set dsmask; 138*7c478bd9Sstevel@tonic-gate struct timeval timeout; 139*7c478bd9Sstevel@tonic-gate HEADER *hp = (HEADER *) buf; 140*7c478bd9Sstevel@tonic-gate HEADER *anhp = (HEADER *) answer; 141*7c478bd9Sstevel@tonic-gate struct iovec iov[2]; 142*7c478bd9Sstevel@tonic-gate int terrno = ETIMEDOUT; 143*7c478bd9Sstevel@tonic-gate char junk[512]; 144*7c478bd9Sstevel@tonic-gate 145*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 146*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) { 147*7c478bd9Sstevel@tonic-gate printf("res_send()\n"); 148*7c478bd9Sstevel@tonic-gate p_query(buf); 149*7c478bd9Sstevel@tonic-gate } 150*7c478bd9Sstevel@tonic-gate #endif DEBUG 151*7c478bd9Sstevel@tonic-gate if (!(_res.options & RES_INIT)) 152*7c478bd9Sstevel@tonic-gate if (res_init() == -1) { 153*7c478bd9Sstevel@tonic-gate return (-1); 154*7c478bd9Sstevel@tonic-gate } 155*7c478bd9Sstevel@tonic-gate 156*7c478bd9Sstevel@tonic-gate /* 1247019: Check to see if we can bailout quickly. */ 157*7c478bd9Sstevel@tonic-gate if (_confcheck() == -1) 158*7c478bd9Sstevel@tonic-gate return(-1); 159*7c478bd9Sstevel@tonic-gate 160*7c478bd9Sstevel@tonic-gate v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ; 161*7c478bd9Sstevel@tonic-gate id = hp->id; 162*7c478bd9Sstevel@tonic-gate /* 163*7c478bd9Sstevel@tonic-gate * Send request, RETRY times, or until successful 164*7c478bd9Sstevel@tonic-gate */ 165*7c478bd9Sstevel@tonic-gate for (try = 0; try < _res.retry; try++) { 166*7c478bd9Sstevel@tonic-gate for (ns = 0; ns < _res.nscount; ns++) { 167*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 168*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 169*7c478bd9Sstevel@tonic-gate printf("Querying server (# %d) address = %s\n", 170*7c478bd9Sstevel@tonic-gate ns+1, inet_ntoa(_res.nsaddr_list[ns].sin_addr)); 171*7c478bd9Sstevel@tonic-gate #endif DEBUG 172*7c478bd9Sstevel@tonic-gate usevc: 173*7c478bd9Sstevel@tonic-gate if (v_circuit) { 174*7c478bd9Sstevel@tonic-gate int truncated = 0; 175*7c478bd9Sstevel@tonic-gate 176*7c478bd9Sstevel@tonic-gate /* 177*7c478bd9Sstevel@tonic-gate * Use virtual circuit; 178*7c478bd9Sstevel@tonic-gate * at most one attempt per server. 179*7c478bd9Sstevel@tonic-gate */ 180*7c478bd9Sstevel@tonic-gate try = _res.retry; 181*7c478bd9Sstevel@tonic-gate if (s < 0) { 182*7c478bd9Sstevel@tonic-gate s = _socket(AF_INET, SOCK_STREAM, 0); 183*7c478bd9Sstevel@tonic-gate if (s < 0) { 184*7c478bd9Sstevel@tonic-gate terrno = errno; 185*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 186*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) { 187*7c478bd9Sstevel@tonic-gate perror("socket (vc) failed"); 188*7c478bd9Sstevel@tonic-gate } 189*7c478bd9Sstevel@tonic-gate #endif DEBUG 190*7c478bd9Sstevel@tonic-gate continue; 191*7c478bd9Sstevel@tonic-gate } 192*7c478bd9Sstevel@tonic-gate if (connect(s, (struct sockaddr *) &_res.nsaddr_list[ns], 193*7c478bd9Sstevel@tonic-gate sizeof (struct sockaddr)) < 0) { 194*7c478bd9Sstevel@tonic-gate terrno = errno; 195*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 196*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) { 197*7c478bd9Sstevel@tonic-gate perror("connect failed"); 198*7c478bd9Sstevel@tonic-gate } 199*7c478bd9Sstevel@tonic-gate #endif DEBUG 200*7c478bd9Sstevel@tonic-gate (void) close(s); 201*7c478bd9Sstevel@tonic-gate s = -1; 202*7c478bd9Sstevel@tonic-gate continue; 203*7c478bd9Sstevel@tonic-gate } 204*7c478bd9Sstevel@tonic-gate } 205*7c478bd9Sstevel@tonic-gate /* 206*7c478bd9Sstevel@tonic-gate * Send length & message 207*7c478bd9Sstevel@tonic-gate */ 208*7c478bd9Sstevel@tonic-gate len = htons((u_short)buflen); 209*7c478bd9Sstevel@tonic-gate iov[0].iov_base = (caddr_t)&len; 210*7c478bd9Sstevel@tonic-gate iov[0].iov_len = sizeof (len); 211*7c478bd9Sstevel@tonic-gate iov[1].iov_base = buf; 212*7c478bd9Sstevel@tonic-gate iov[1].iov_len = buflen; 213*7c478bd9Sstevel@tonic-gate if (writev(s, iov, 2) != sizeof (len) + 214*7c478bd9Sstevel@tonic-gate buflen) { 215*7c478bd9Sstevel@tonic-gate terrno = errno; 216*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 217*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 218*7c478bd9Sstevel@tonic-gate perror("write failed"); 219*7c478bd9Sstevel@tonic-gate #endif DEBUG 220*7c478bd9Sstevel@tonic-gate (void) close(s); 221*7c478bd9Sstevel@tonic-gate s = -1; 222*7c478bd9Sstevel@tonic-gate continue; 223*7c478bd9Sstevel@tonic-gate } 224*7c478bd9Sstevel@tonic-gate /* 225*7c478bd9Sstevel@tonic-gate * Receive length & response 226*7c478bd9Sstevel@tonic-gate */ 227*7c478bd9Sstevel@tonic-gate cp = answer; 228*7c478bd9Sstevel@tonic-gate len = sizeof (short); 229*7c478bd9Sstevel@tonic-gate while (len != 0 && (n = read 230*7c478bd9Sstevel@tonic-gate (s, (char *)cp, (int)len)) > 0) { 231*7c478bd9Sstevel@tonic-gate cp += n; 232*7c478bd9Sstevel@tonic-gate len -= n; 233*7c478bd9Sstevel@tonic-gate } 234*7c478bd9Sstevel@tonic-gate if (n <= 0) { 235*7c478bd9Sstevel@tonic-gate terrno = errno; 236*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 237*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 238*7c478bd9Sstevel@tonic-gate perror("read failed"); 239*7c478bd9Sstevel@tonic-gate #endif DEBUG 240*7c478bd9Sstevel@tonic-gate (void) close(s); 241*7c478bd9Sstevel@tonic-gate s = -1; 242*7c478bd9Sstevel@tonic-gate /* 243*7c478bd9Sstevel@tonic-gate * A long running process might get its TCP 244*7c478bd9Sstevel@tonic-gate * connection reset if the remote server was 245*7c478bd9Sstevel@tonic-gate * restarted. Requery the server instead of 246*7c478bd9Sstevel@tonic-gate * trying a new one. When there is only one 247*7c478bd9Sstevel@tonic-gate * server, this means that a query might work 248*7c478bd9Sstevel@tonic-gate * instead of failing. We only allow one reset 249*7c478bd9Sstevel@tonic-gate * per query to prevent looping. 250*7c478bd9Sstevel@tonic-gate */ 251*7c478bd9Sstevel@tonic-gate if (terrno == ECONNRESET && 252*7c478bd9Sstevel@tonic-gate !connreset) { 253*7c478bd9Sstevel@tonic-gate connreset = 1; 254*7c478bd9Sstevel@tonic-gate ns--; 255*7c478bd9Sstevel@tonic-gate } 256*7c478bd9Sstevel@tonic-gate continue; 257*7c478bd9Sstevel@tonic-gate } 258*7c478bd9Sstevel@tonic-gate cp = answer; 259*7c478bd9Sstevel@tonic-gate if ((resplen = ntohs(*(u_short *)cp)) > 260*7c478bd9Sstevel@tonic-gate anslen) { 261*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 262*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 263*7c478bd9Sstevel@tonic-gate fprintf(stderr, 264*7c478bd9Sstevel@tonic-gate "response truncated\n"); 265*7c478bd9Sstevel@tonic-gate #endif DEBUG 266*7c478bd9Sstevel@tonic-gate len = anslen; 267*7c478bd9Sstevel@tonic-gate truncated = 1; 268*7c478bd9Sstevel@tonic-gate } else 269*7c478bd9Sstevel@tonic-gate len = resplen; 270*7c478bd9Sstevel@tonic-gate while (len != 0 && 271*7c478bd9Sstevel@tonic-gate (n = read(s, (char *)cp, 272*7c478bd9Sstevel@tonic-gate (int)len)) > 0) { 273*7c478bd9Sstevel@tonic-gate cp += n; 274*7c478bd9Sstevel@tonic-gate len -= n; 275*7c478bd9Sstevel@tonic-gate } 276*7c478bd9Sstevel@tonic-gate if (n <= 0) { 277*7c478bd9Sstevel@tonic-gate terrno = errno; 278*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 279*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 280*7c478bd9Sstevel@tonic-gate perror("read failed"); 281*7c478bd9Sstevel@tonic-gate #endif DEBUG 282*7c478bd9Sstevel@tonic-gate (void) close(s); 283*7c478bd9Sstevel@tonic-gate s = -1; 284*7c478bd9Sstevel@tonic-gate continue; 285*7c478bd9Sstevel@tonic-gate } 286*7c478bd9Sstevel@tonic-gate if (truncated) { 287*7c478bd9Sstevel@tonic-gate /* 288*7c478bd9Sstevel@tonic-gate * Flush rest of answer 289*7c478bd9Sstevel@tonic-gate * so connection stays in synch. 290*7c478bd9Sstevel@tonic-gate */ 291*7c478bd9Sstevel@tonic-gate anhp->tc = 1; 292*7c478bd9Sstevel@tonic-gate len = resplen - anslen; 293*7c478bd9Sstevel@tonic-gate /* 294*7c478bd9Sstevel@tonic-gate * set the value of resplen to anslen, 295*7c478bd9Sstevel@tonic-gate * this is done because the caller 296*7c478bd9Sstevel@tonic-gate * assumes resplen contains the size of 297*7c478bd9Sstevel@tonic-gate * message read into the "answer" buffer 298*7c478bd9Sstevel@tonic-gate * passed in. 299*7c478bd9Sstevel@tonic-gate */ 300*7c478bd9Sstevel@tonic-gate resplen = anslen; 301*7c478bd9Sstevel@tonic-gate 302*7c478bd9Sstevel@tonic-gate while (len != 0) { 303*7c478bd9Sstevel@tonic-gate n = (len > sizeof (junk) ? 304*7c478bd9Sstevel@tonic-gate sizeof (junk) : len); 305*7c478bd9Sstevel@tonic-gate if ((n = read(s, junk, n)) > 0) 306*7c478bd9Sstevel@tonic-gate len -= n; 307*7c478bd9Sstevel@tonic-gate else 308*7c478bd9Sstevel@tonic-gate break; 309*7c478bd9Sstevel@tonic-gate } 310*7c478bd9Sstevel@tonic-gate } 311*7c478bd9Sstevel@tonic-gate } else { 312*7c478bd9Sstevel@tonic-gate /* 313*7c478bd9Sstevel@tonic-gate * Use datagrams. 314*7c478bd9Sstevel@tonic-gate */ 315*7c478bd9Sstevel@tonic-gate if (s < 0) { 316*7c478bd9Sstevel@tonic-gate s = _socket(AF_INET, SOCK_DGRAM, 0); 317*7c478bd9Sstevel@tonic-gate if (s < 0) { 318*7c478bd9Sstevel@tonic-gate terrno = errno; 319*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 320*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) { 321*7c478bd9Sstevel@tonic-gate perror("socket (dg) failed"); 322*7c478bd9Sstevel@tonic-gate } 323*7c478bd9Sstevel@tonic-gate #endif DEBUG 324*7c478bd9Sstevel@tonic-gate continue; 325*7c478bd9Sstevel@tonic-gate } 326*7c478bd9Sstevel@tonic-gate } 327*7c478bd9Sstevel@tonic-gate #if BSD >= 43 328*7c478bd9Sstevel@tonic-gate /* 329*7c478bd9Sstevel@tonic-gate * I'm tired of answering this question, so: 330*7c478bd9Sstevel@tonic-gate * On a 4.3BSD+ machine (client and server, 331*7c478bd9Sstevel@tonic-gate * actually), sending to a nameserver datagram 332*7c478bd9Sstevel@tonic-gate * port with no nameserver will cause an 333*7c478bd9Sstevel@tonic-gate * ICMP port unreachable message to be returned. 334*7c478bd9Sstevel@tonic-gate * If our datagram socket is "connected" to the 335*7c478bd9Sstevel@tonic-gate * server, we get an ECONNREFUSED error on the next 336*7c478bd9Sstevel@tonic-gate * socket operation, and select returns if the 337*7c478bd9Sstevel@tonic-gate * error message is received. We can thus detect 338*7c478bd9Sstevel@tonic-gate * the absence of a nameserver without timing out. 339*7c478bd9Sstevel@tonic-gate * If we have sent queries to at least two servers, 340*7c478bd9Sstevel@tonic-gate * however, we don't want to remain connected, 341*7c478bd9Sstevel@tonic-gate * as we wish to receive answers from the first 342*7c478bd9Sstevel@tonic-gate * server to respond. 343*7c478bd9Sstevel@tonic-gate */ 344*7c478bd9Sstevel@tonic-gate if (_res.nscount == 1 || 345*7c478bd9Sstevel@tonic-gate (try == 0 && ns == 0)) { 346*7c478bd9Sstevel@tonic-gate /* 347*7c478bd9Sstevel@tonic-gate * Don't use connect if we might 348*7c478bd9Sstevel@tonic-gate * still receive a response 349*7c478bd9Sstevel@tonic-gate * from another server. 350*7c478bd9Sstevel@tonic-gate */ 351*7c478bd9Sstevel@tonic-gate if (connected == 0) { 352*7c478bd9Sstevel@tonic-gate if (connect(s, 353*7c478bd9Sstevel@tonic-gate (struct sockaddr *) &_res.nsaddr_list[ns], 354*7c478bd9Sstevel@tonic-gate sizeof (struct sockaddr)) < 0) { 355*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 356*7c478bd9Sstevel@tonic-gate if (_res.options & 357*7c478bd9Sstevel@tonic-gate RES_DEBUG) { 358*7c478bd9Sstevel@tonic-gate perror("connect"); 359*7c478bd9Sstevel@tonic-gate } 360*7c478bd9Sstevel@tonic-gate #endif DEBUG 361*7c478bd9Sstevel@tonic-gate continue; 362*7c478bd9Sstevel@tonic-gate } 363*7c478bd9Sstevel@tonic-gate connected = 1; 364*7c478bd9Sstevel@tonic-gate } 365*7c478bd9Sstevel@tonic-gate if (send(s, buf, buflen, 0) != buflen) { 366*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 367*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 368*7c478bd9Sstevel@tonic-gate perror("send"); 369*7c478bd9Sstevel@tonic-gate #endif DEBUG 370*7c478bd9Sstevel@tonic-gate continue; 371*7c478bd9Sstevel@tonic-gate } 372*7c478bd9Sstevel@tonic-gate } else { 373*7c478bd9Sstevel@tonic-gate /* 374*7c478bd9Sstevel@tonic-gate * Disconnect if we want to listen for 375*7c478bd9Sstevel@tonic-gate * responses from more than one server. 376*7c478bd9Sstevel@tonic-gate */ 377*7c478bd9Sstevel@tonic-gate if (connected) { 378*7c478bd9Sstevel@tonic-gate (void) connect(s, &no_addr, 379*7c478bd9Sstevel@tonic-gate sizeof (no_addr)); 380*7c478bd9Sstevel@tonic-gate connected = 0; 381*7c478bd9Sstevel@tonic-gate } 382*7c478bd9Sstevel@tonic-gate #endif BSD 383*7c478bd9Sstevel@tonic-gate if (sendto(s, buf, buflen, 0, 384*7c478bd9Sstevel@tonic-gate (struct sockaddr *) &_res.nsaddr_list[ns], 385*7c478bd9Sstevel@tonic-gate sizeof (struct sockaddr)) != buflen) { 386*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 387*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 388*7c478bd9Sstevel@tonic-gate perror("sendto"); 389*7c478bd9Sstevel@tonic-gate #endif DEBUG 390*7c478bd9Sstevel@tonic-gate continue; 391*7c478bd9Sstevel@tonic-gate } 392*7c478bd9Sstevel@tonic-gate #if BSD >= 43 393*7c478bd9Sstevel@tonic-gate } 394*7c478bd9Sstevel@tonic-gate #endif 395*7c478bd9Sstevel@tonic-gate 396*7c478bd9Sstevel@tonic-gate /* 397*7c478bd9Sstevel@tonic-gate * Wait for reply 398*7c478bd9Sstevel@tonic-gate */ 399*7c478bd9Sstevel@tonic-gate timeout.tv_sec = (_res.retrans << try); 400*7c478bd9Sstevel@tonic-gate if (try > 0) 401*7c478bd9Sstevel@tonic-gate timeout.tv_sec /= _res.nscount; 402*7c478bd9Sstevel@tonic-gate if (timeout.tv_sec <= 0) 403*7c478bd9Sstevel@tonic-gate timeout.tv_sec = 1; 404*7c478bd9Sstevel@tonic-gate timeout.tv_usec = 0; 405*7c478bd9Sstevel@tonic-gate wait: 406*7c478bd9Sstevel@tonic-gate FD_ZERO(&dsmask); 407*7c478bd9Sstevel@tonic-gate FD_SET(s, &dsmask); 408*7c478bd9Sstevel@tonic-gate n = select(s+1, &dsmask, (fd_set *)NULL, 409*7c478bd9Sstevel@tonic-gate (fd_set *)NULL, &timeout); 410*7c478bd9Sstevel@tonic-gate if (n < 0) { 411*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 412*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 413*7c478bd9Sstevel@tonic-gate perror("select"); 414*7c478bd9Sstevel@tonic-gate #endif DEBUG 415*7c478bd9Sstevel@tonic-gate continue; 416*7c478bd9Sstevel@tonic-gate } 417*7c478bd9Sstevel@tonic-gate if (n == 0) { 418*7c478bd9Sstevel@tonic-gate /* 419*7c478bd9Sstevel@tonic-gate * timeout 420*7c478bd9Sstevel@tonic-gate */ 421*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 422*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 423*7c478bd9Sstevel@tonic-gate printf("timeout\n"); 424*7c478bd9Sstevel@tonic-gate #endif DEBUG 425*7c478bd9Sstevel@tonic-gate #if BSD >= 43 426*7c478bd9Sstevel@tonic-gate gotsomewhere = 1; 427*7c478bd9Sstevel@tonic-gate #endif 428*7c478bd9Sstevel@tonic-gate continue; 429*7c478bd9Sstevel@tonic-gate } 430*7c478bd9Sstevel@tonic-gate if ((resplen = recv(s, answer, anslen, 0)) 431*7c478bd9Sstevel@tonic-gate <= 0) { 432*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 433*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 434*7c478bd9Sstevel@tonic-gate perror("recvfrom"); 435*7c478bd9Sstevel@tonic-gate #endif DEBUG 436*7c478bd9Sstevel@tonic-gate continue; 437*7c478bd9Sstevel@tonic-gate } 438*7c478bd9Sstevel@tonic-gate gotsomewhere = 1; 439*7c478bd9Sstevel@tonic-gate if (id != anhp->id) { 440*7c478bd9Sstevel@tonic-gate /* 441*7c478bd9Sstevel@tonic-gate * response from old query, ignore it 442*7c478bd9Sstevel@tonic-gate */ 443*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 444*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) { 445*7c478bd9Sstevel@tonic-gate printf("old answer:\n"); 446*7c478bd9Sstevel@tonic-gate p_query(answer); 447*7c478bd9Sstevel@tonic-gate } 448*7c478bd9Sstevel@tonic-gate #endif DEBUG 449*7c478bd9Sstevel@tonic-gate goto wait; 450*7c478bd9Sstevel@tonic-gate } 451*7c478bd9Sstevel@tonic-gate if (!(_res.options & RES_IGNTC) && anhp->tc) { 452*7c478bd9Sstevel@tonic-gate /* 453*7c478bd9Sstevel@tonic-gate * get rest of answer; 454*7c478bd9Sstevel@tonic-gate * use TCP with same server. 455*7c478bd9Sstevel@tonic-gate */ 456*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 457*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) 458*7c478bd9Sstevel@tonic-gate printf("truncated answer\n"); 459*7c478bd9Sstevel@tonic-gate #endif DEBUG 460*7c478bd9Sstevel@tonic-gate (void) close(s); 461*7c478bd9Sstevel@tonic-gate s = -1; 462*7c478bd9Sstevel@tonic-gate v_circuit = 1; 463*7c478bd9Sstevel@tonic-gate goto usevc; 464*7c478bd9Sstevel@tonic-gate } 465*7c478bd9Sstevel@tonic-gate } 466*7c478bd9Sstevel@tonic-gate #ifdef DEBUG 467*7c478bd9Sstevel@tonic-gate if (_res.options & RES_DEBUG) { 468*7c478bd9Sstevel@tonic-gate printf("got answer:\n"); 469*7c478bd9Sstevel@tonic-gate p_query(answer); 470*7c478bd9Sstevel@tonic-gate } 471*7c478bd9Sstevel@tonic-gate #endif DEBUG 472*7c478bd9Sstevel@tonic-gate /* 473*7c478bd9Sstevel@tonic-gate * If using virtual circuits, we assume that the first server 474*7c478bd9Sstevel@tonic-gate * is preferred * over the rest (i.e. it is on the local 475*7c478bd9Sstevel@tonic-gate * machine) and only keep that one open. 476*7c478bd9Sstevel@tonic-gate * If we have temporarily opened a virtual circuit, 477*7c478bd9Sstevel@tonic-gate * or if we haven't been asked to keep a socket open, 478*7c478bd9Sstevel@tonic-gate * close the socket. 479*7c478bd9Sstevel@tonic-gate */ 480*7c478bd9Sstevel@tonic-gate if ((v_circuit && 481*7c478bd9Sstevel@tonic-gate ((_res.options & RES_USEVC) == 0 || ns != 0)) || 482*7c478bd9Sstevel@tonic-gate (_res.options & RES_STAYOPEN) == 0) { 483*7c478bd9Sstevel@tonic-gate (void) close(s); 484*7c478bd9Sstevel@tonic-gate s = -1; 485*7c478bd9Sstevel@tonic-gate } 486*7c478bd9Sstevel@tonic-gate return (resplen); 487*7c478bd9Sstevel@tonic-gate } 488*7c478bd9Sstevel@tonic-gate } 489*7c478bd9Sstevel@tonic-gate if (s >= 0) { 490*7c478bd9Sstevel@tonic-gate (void) close(s); 491*7c478bd9Sstevel@tonic-gate s = -1; 492*7c478bd9Sstevel@tonic-gate } 493*7c478bd9Sstevel@tonic-gate if (v_circuit == 0) 494*7c478bd9Sstevel@tonic-gate if (gotsomewhere == 0) 495*7c478bd9Sstevel@tonic-gate errno = ECONNREFUSED; /* no nameservers found */ 496*7c478bd9Sstevel@tonic-gate else 497*7c478bd9Sstevel@tonic-gate errno = ETIMEDOUT; /* no answer obtained */ 498*7c478bd9Sstevel@tonic-gate else 499*7c478bd9Sstevel@tonic-gate errno = terrno; 500*7c478bd9Sstevel@tonic-gate return (-1); 501*7c478bd9Sstevel@tonic-gate } 502*7c478bd9Sstevel@tonic-gate 503*7c478bd9Sstevel@tonic-gate /* 504*7c478bd9Sstevel@tonic-gate * This routine is for closing the socket if a virtual circuit is used and 505*7c478bd9Sstevel@tonic-gate * the program wants to close it. This provides support for endhostent() 506*7c478bd9Sstevel@tonic-gate * which expects to close the socket. 507*7c478bd9Sstevel@tonic-gate * 508*7c478bd9Sstevel@tonic-gate * This routine is not expected to be user visible. 509*7c478bd9Sstevel@tonic-gate */ 510*7c478bd9Sstevel@tonic-gate _res_close() 511*7c478bd9Sstevel@tonic-gate { 512*7c478bd9Sstevel@tonic-gate if (s != -1) { 513*7c478bd9Sstevel@tonic-gate (void) close(s); 514*7c478bd9Sstevel@tonic-gate s = -1; 515*7c478bd9Sstevel@tonic-gate } 516*7c478bd9Sstevel@tonic-gate } 517