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NetBSD/lib/libc/net/res_send.c

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/* $NetBSD: res_send.c,v 1.4 1995/02/25 06:21:01 cgd Exp $ */
/*-
* 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[] = "$Id: res_send.c,v 4.9.1.1 1993/05/02 22:43:03 vixie Rel ";
#else
static char rcsid[] = "$NetBSD: res_send.c,v 1.4 1995/02/25 06:21:01 cgd Exp $";
#endif
#endif /* LIBC_SCCS and not lint */
/*
* Send query to name server and wait for reply.
*/
#include <sys/param.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <errno.h>
#include <resolv.h>
#include <unistd.h>
#include <string.h>
static int s = -1; /* socket used for communications */
static struct sockaddr no_addr;
#ifndef FD_SET
#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
res_send(buf, buflen, answer, anslen)
const char *buf;
int buflen;
char *answer;
int anslen;
{
register int n;
int try, v_circuit, resplen, ns;
int gotsomewhere = 0, connected = 0;
int connreset = 0;
u_short id, len;
char *cp;
fd_set dsmask;
struct timeval timeout;
HEADER *hp = (HEADER *) buf;
HEADER *anhp = (HEADER *) answer;
u_int badns; /* XXX NSMAX can't exceed #/bits per this */
struct iovec iov[2];
int terrno = ETIMEDOUT;
char junk[512];
#ifdef DEBUG
if ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY)) {
printf(";; res_send()\n");
__p_query(buf);
}
#endif
if (!(_res.options & RES_INIT))
if (res_init() == -1) {
return(-1);
}
v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
id = hp->id;
badns = 0;
/*
* Send request, RETRY times, or until successful
*/
for (try = 0; try < _res.retry; try++) {
for (ns = 0; ns < _res.nscount; ns++) {
if (badns & (1<<ns))
continue;
#ifdef DEBUG
if (_res.options & RES_DEBUG)
printf(";; Querying server (# %d) address = %s\n",
ns+1,
inet_ntoa(_res.nsaddr_list[ns].sin_addr));
#endif
usevc:
if (v_circuit) {
int truncated = 0;
/*
* Use virtual circuit;
* at most one attempt per server.
*/
try = _res.retry;
if (s < 0) {
s = socket(AF_INET, SOCK_STREAM, 0);
if (s < 0) {
terrno = errno;
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("socket (vc) failed");
#endif
continue;
}
if (connect(s,
(struct sockaddr *)&(_res.nsaddr_list[ns]),
sizeof(struct sockaddr)) < 0) {
terrno = errno;
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("connect failed");
#endif
(void) close(s);
s = -1;
continue;
}
}
/*
* Send length & message
*/
len = htons((u_short)buflen);
iov[0].iov_base = (caddr_t)&len;
iov[0].iov_len = sizeof(len);
iov[1].iov_base = (char *)buf;
iov[1].iov_len = buflen;
if (writev(s, iov, 2) != sizeof(len) + buflen) {
terrno = errno;
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("write failed");
#endif
(void) close(s);
s = -1;
continue;
}
/*
* Receive length & response
*/
cp = answer;
len = sizeof(short);
while (len != 0 &&
(n = read(s, (char *)cp, (int)len)) > 0) {
cp += n;
len -= n;
}
if (n <= 0) {
terrno = errno;
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("read failed");
#endif
(void) close(s);
s = -1;
/*
* 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;
ns--;
}
continue;
}
cp = answer;
if ((resplen = ntohs(*(u_short *)cp)) > anslen) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
fprintf(stderr,
";; response truncated\n");
#endif
len = anslen;
truncated = 1;
} else
len = resplen;
while (len != 0 &&
(n = read(s, (char *)cp, (int)len)) > 0) {
cp += n;
len -= n;
}
if (n <= 0) {
terrno = errno;
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("read failed");
#endif
(void) close(s);
s = -1;
continue;
}
if (truncated) {
/*
* Flush rest of answer
* so connection stays in synch.
*/
anhp->tc = 1;
len = resplen - anslen;
while (len != 0) {
n = (len > sizeof(junk) ?
sizeof(junk) : len);
if ((n = read(s, junk, n)) > 0)
len -= n;
else
break;
}
}
} else {
/*
* Use datagrams.
*/
if (s < 0) {
s = socket(AF_INET, SOCK_DGRAM, 0);
if (s < 0) {
terrno = errno;
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("socket (dg) failed");
#endif
continue;
}
}
/*
* I'm tired of answering this question, so:
* 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)) {
/*
* Don't use connect if we might
* still receive a response
* from another server.
*/
if (connected == 0) {
if (connect(s,
(struct sockaddr *)
&_res.nsaddr_list[ns],
sizeof(struct sockaddr)) < 0) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("connect");
#endif
continue;
}
connected = 1;
}
if (send(s, buf, buflen, 0) != buflen) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("send");
#endif
continue;
}
} else {
/*
* Disconnect if we want to listen
* for responses from more than one server.
*/
if (connected) {
(void) connect(s, &no_addr,
sizeof(no_addr));
connected = 0;
}
if (sendto(s, buf, buflen, 0,
(struct sockaddr *)&_res.nsaddr_list[ns],
sizeof(struct sockaddr)) != buflen) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("sendto");
#endif
continue;
}
}
/*
* 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) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("select");
#endif
continue;
}
if (n == 0) {
/*
* timeout
*/
#ifdef DEBUG
if (_res.options & RES_DEBUG)
printf(";; timeout\n");
#endif
gotsomewhere = 1;
continue;
}
if ((resplen = recv(s, answer, anslen, 0)) <= 0) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("recvfrom");
#endif
continue;
}
gotsomewhere = 1;
if (id != anhp->id) {
/*
* response from old query, ignore it
*/
#ifdef DEBUG
if ((_res.options & RES_DEBUG) ||
(_res.pfcode & RES_PRF_REPLY)) {
printf(";; old answer:\n");
__p_query(answer);
}
#endif
goto wait;
}
if (anhp->rcode == SERVFAIL || anhp->rcode == NOTIMP ||
anhp->rcode == REFUSED) {
#ifdef DEBUG
if (_res.options & RES_DEBUG) {
printf("server rejected query:\n");
__p_query(answer);
}
#endif
badns |= (1<<ns);
continue;
}
if (!(_res.options & RES_IGNTC) && anhp->tc) {
/*
* get rest of answer;
* use TCP with same server.
*/
#ifdef DEBUG
if (_res.options & RES_DEBUG)
printf(";; truncated answer\n");
#endif
(void) close(s);
s = -1;
v_circuit = 1;
goto usevc;
}
}
#ifdef DEBUG
if (_res.options & RES_DEBUG)
printf(";; got answer:\n");
if ((_res.options & RES_DEBUG) ||
(_res.pfcode & RES_PRF_REPLY))
__p_query(answer);
#endif
/*
* 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) == 0 || ns != 0)) ||
(_res.options & RES_STAYOPEN) == 0) {
(void) close(s);
s = -1;
}
return (resplen);
}
}
if (s >= 0) {
(void) close(s);
s = -1;
}
if (v_circuit == 0)
if (gotsomewhere == 0)
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.
*/
_res_close()
{
if (s != -1) {
(void) close(s);
s = -1;
}
}
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