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glibc/resolv/res_send.c

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/*
* ++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.
* 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)
static char sccsid[] = "@(#)res_send.c 8.1 (Berkeley) 6/4/93";
static char rcsid[] = "$Id$";
#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 <sys/types.h>
#include <sys/param.h>
#include <sys/poll.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 <netdb.h>
#include <errno.h>
#include <resolv.h>
#if defined(BSD) && (BSD >= 199306)
# include <stdlib.h>
# include <string.h>
# include <unistd.h>
#else
# include "../conf/portability.h"
#endif
#include <bits/libc-lock.h>
/* Lock to protect the connection use. */
__libc_lock_define_initialized (static, lock)
static void res_close_internal (void);
#if defined(USE_OPTIONS_H)
# include <../conf/options.h>
#endif
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 circuit? */
/* XXX - this should be done in portability.h */
#if (defined(BSD) && (BSD >= 199103)) || defined(linux)
# define CAN_RECONNECT 1
#else
# define CAN_RECONNECT 0
#endif
#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));
}
__set_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));
}
__set_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)
* requires:
* buf + HFIXESDZ <= 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;
if (cp + 2 * INT16SZ > eom)
return (-1);
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 (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
return (-1);
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;
if (cp + 2 * INT16SZ > eom1)
return (-1);
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 */
int result = -1;
if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
/* errno should have been set by res_init() in this case. */
return (-1);
}
if (anssiz < HFIXEDSZ) {
__set_errno (EINVAL);
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;
__libc_lock_lock (lock);
/*
* 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_internal();
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_internal();
goto next_ns;
case res_done:
result = resplen;
goto and_out;
case res_modified:
/* give the hook another try */
if (++loops < 42) /*doug adams*/
break;
/*FALLTHROUGH*/
case res_error:
/*FALLTHROUGH*/
default:
goto and_out;
}
} 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_internal();
s = socket(PF_INET, SOCK_STREAM, 0);
if (s < 0) {
terrno = errno;
Perror(stderr, "socket(vc)", errno);
goto and_out;
}
__set_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_internal();
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_internal();
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_internal();
/*
* 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_internal();
goto same_ns;
}
res_close_internal();
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;
if (len < HFIXEDSZ) {
/*
* Undersized message.
*/
Dprint(_res.options & RES_DEBUG,
(stdout, ";; undersized: %d\n", len));
terrno = EMSGSIZE;
badns |= (1 << ns);
res_close_internal();
goto next_ns;
}
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_internal();
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 = ((size_t) 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.
*/
int timeout;
struct pollfd pfd[1];
struct sockaddr_in from;
socklen_t fromlen;
time_t curtime;
time_t endtime;
if ((s < 0) || vc) {
if (vc)
res_close_internal();
s = socket(PF_INET, SOCK_DGRAM, 0);
if (s < 0) {
#if !CAN_RECONNECT
bad_dg_sock:
#endif
terrno = errno;
Perror(stderr, "socket(dg)", errno);
goto and_out;
}
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_internal();
goto next_ns;
}
connected = 1;
}
if (send(s, (char*)buf, buflen, 0) != buflen) {
Perror(stderr, "send", errno);
badns |= (1 << ns);
res_close_internal();
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;
__set_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_internal();
goto next_ns;
}
}
/*
* Wait for reply
*/
curtime = time (NULL);
if (try > 0)
endtime = (_res.retrans << try) / _res.nscount;
else {
endtime = _res.retrans;
if (endtime <= 0)
endtime = 1;
}
endtime += curtime;
wait:
timeout = MAX (endtime - curtime, 0) * 1000;
#if 0
if (s < 0 || s >= FD_SETSIZE) {
Perror(stderr, "s out-of-bounds", EMFILE);
res_close_internal();
goto next_ns;
}
#endif
pfd[0].fd = s;
pfd[0].events = POLLIN;
n = __poll(pfd, 1, timeout);
if (n < 0) {
if (errno == EINTR) {
curtime = time (NULL);
goto wait;
}
Perror(stderr, "poll", errno);
res_close_internal();
goto next_ns;
}
if (n == 0) {
/*
* timeout
*/
Dprint(_res.options & RES_DEBUG,
(stdout, ";; timeout\n"));
gotsomewhere = 1;
res_close_internal();
goto next_ns;
}
__set_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_internal();
goto next_ns;
}
gotsomewhere = 1;
if (resplen < HFIXEDSZ) {
/*
* Undersized message.
*/
Dprint(_res.options & RES_DEBUG,
(stdout, ";; undersized: %d\n",
resplen));
terrno = EMSGSIZE;
badns |= (1 << ns);
res_close_internal();
goto next_ns;
}
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);
curtime = time (NULL);
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);
curtime = time (NULL);
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);
curtime = time (NULL);
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_internal();
/* 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_internal();
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_internal();
}
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_internal();
goto next_ns;
case res_modified:
/* give the hook another try */
if (++loops < 42) /*doug adams*/
break;
/*FALLTHROUGH*/
case res_error:
/*FALLTHROUGH*/
default:
goto and_out;
}
} while (!done);
}
result = resplen;
goto and_out;
next_ns: ;
} /*foreach ns*/
} /*foreach retry*/
res_close_internal();
if (!v_circuit) {
if (!gotsomewhere)
__set_errno (ECONNREFUSED); /* no nameservers found */
else
__set_errno (ETIMEDOUT); /* no answer obtained */
} else
__set_errno (terrno);
and_out:
__libc_lock_unlock (lock);
return result;
}
/*
* 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.
*/
static void
res_close_internal()
{
if (s >= 0) {
(void) close(s);
s = -1;
connected = 0;
vc = 0;
}
}
void
res_close ()
{
__libc_lock_lock (lock);
res_close_internal ();
__libc_lock_unlock (lock);
}
#ifdef ultrix
/* ultrix 4.0 had some icky packaging in its libc.a. alias for it here.
* there is more gunk of this kind over in res_debug.c.
*/
void
_res_close()
{
res_close();
}
#undef res_send
int
res_send(buf, buflen, ans, anssiz)
const u_char *buf;
int buflen;
u_char *ans;
int anssiz;
{
return (__res_send(buf, buflen, ans, anssiz));
}
#endif /* Ultrix 4.0 hackery */
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