4.3BSD-Reno/src/usr.sbin/named/tools/nslookup/send.c
/*
* Copyright (c) 1985, 1989 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted provided
* that: (1) source distributions retain this entire copyright notice and
* comment, and (2) distributions including binaries display the following
* acknowledgement: ``This product includes software developed by the
* University of California, Berkeley and its contributors'' in the
* documentation or other materials provided with the distribution and in
* all advertising materials mentioning features or use of this software.
* 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char sccsid[] = "@(#)send.c 5.17 (Berkeley) 6/29/90";
#endif /* not lint */
/*
*******************************************************************************
*
* send.c --
*
* Routine to send request packets to a name server.
*
* Based on "@(#)res_send.c 6.25 (Berkeley) 6/1/90".
*
*******************************************************************************
*/
/*
* 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 <stdio.h>
#include <errno.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>
#include <resolv.h>
#include "res.h"
extern int errno;
static int s = -1; /* socket used for communications */
#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
#define SR 1 /* SendRequest style */
#ifndef DEBUG
#define DEBUG
#endif
unsigned short nsport = NAMESERVER_PORT;
/*
*******************************************************************************
*
* SendRequest --
*
* Sends a request packet to a name server whose address
* is specified by the first argument and returns with
* the answer packet.
*
* Results:
* SUCCESS - the request was sent and an answer
* was received.
* TIME_OUT - the virtual circuit connection timed-out
* or a reply to a datagram wasn't received.
*
*
*******************************************************************************
*/
int
SendRequest(nsAddrPtr, buf, buflen, answer, anslen, trueLenPtr)
struct in_addr *nsAddrPtr;
char *buf;
int buflen;
char *answer;
u_int anslen;
int *trueLenPtr;
{
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;
struct iovec iov[2];
int terrno = ETIMEDOUT;
char junk[512];
#if SR
struct sockaddr_in sin;
if (_res.options & RES_DEBUG2) {
printf("------------\nSendRequest(), len %d\n", buflen);
Print_query(buf, buf+buflen, 1);
}
sin.sin_family = AF_INET;
sin.sin_port = htons(nsport);
sin.sin_addr = *nsAddrPtr;
#else
#ifdef DEBUG
if (_res.options & RES_DEBUG) {
printf("res_send()\n");
p_query(buf);
}
#endif DEBUG
if (!(_res.options & RES_INIT))
if (res_init() == -1) {
return(-1);
}
#endif /* SR */
v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
id = hp->id;
/*
* Send request, RETRY times, or until successful
*/
for (try = 0; try < _res.retry; try++) {
#if !SR
for (ns = 0; ns < _res.nscount; ns++) {
#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 DEBUG
#endif /* !SR */
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 DEBUG
continue;
}
#if SR
if (connect(s, &sin,
#else
if (connect(s, &(_res.nsaddr_list[ns]),
#endif
sizeof(struct sockaddr)) < 0) {
terrno = errno;
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("connect failed");
#endif DEBUG
(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 = 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 DEBUG
(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 DEBUG
(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 DEBUG
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 DEBUG
(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 DEBUG
continue;
}
}
#if SR
/*
* Special case the send code below
* since we have just 1 server.
*/
#if BSD >= 43
if (connected == 0) {
if (connect(s, &sin,
sizeof(struct sockaddr)) < 0) {
if (_res.options & RES_DEBUG)
perror("connect");
continue;
}
connected = 1;
}
if (send(s, buf, buflen, 0) != buflen) {
if (_res.options & RES_DEBUG)
perror("send");
continue;
}
#else /* BSD */
if (sendto(s, buf, buflen, 0, &sin,
sizeof(struct sockaddr)) != buflen) {
if (_res.options & RES_DEBUG)
perror("sendto");
continue;
}
#endif
#else /* SR */
#if BSD >= 43
/*
* 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, &_res.nsaddr_list[ns],
sizeof(struct sockaddr)) < 0) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("connect");
#endif DEBUG
continue;
}
connected = 1;
}
if (send(s, buf, buflen, 0) != buflen) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("send");
#endif DEBUG
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;
}
#endif BSD
if (sendto(s, buf, buflen, 0,
&_res.nsaddr_list[ns],
sizeof(struct sockaddr)) != buflen) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("sendto");
#endif DEBUG
continue;
}
#if BSD >= 43
}
#endif
#endif /* SR */
/*
* Wait for reply
*/
timeout.tv_sec = (_res.retrans << try);
#if !SR
if (try > 0)
timeout.tv_sec /= _res.nscount;
#endif /* SR */
if (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 DEBUG
continue;
}
if (n == 0) {
/*
* timeout
*/
#ifdef DEBUG
if (_res.options & RES_DEBUG)
printf("timeout (%d secs)\n",
timeout.tv_sec);
#endif DEBUG
#if BSD >= 43
gotsomewhere = 1;
#endif
continue;
}
if ((resplen = recv(s, answer, anslen, 0)) <= 0) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
perror("recvfrom");
#endif DEBUG
continue;
}
gotsomewhere = 1;
if (id != anhp->id) {
/*
* response from old query, ignore it
*/
#if SR
if (_res.options & RES_DEBUG2) {
printf("------------\nOld answer:\n");
Print_query(answer, answer+resplen, 1);
}
#else
#ifdef DEBUG
if (_res.options & RES_DEBUG) {
printf("old answer:\n");
p_query(answer);
}
#endif DEBUG
#endif
goto wait;
}
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 DEBUG
(void) close(s);
s = -1;
v_circuit = 1;
goto usevc;
}
}
#if SR
if (_res.options & RES_DEBUG) {
if (_res.options & RES_DEBUG2)
printf("------------\nGot answer (%d bytes):\n",
resplen);
else
printf("------------\nGot answer:\n");
Print_query(answer, answer+resplen, 1);
}
(void) close(s);
s = -1;
*trueLenPtr = resplen;
return (SUCCESS);
#else
#ifdef DEBUG
if (_res.options & RES_DEBUG) {
printf("got answer:\n");
p_query(answer);
}
#endif DEBUG
/*
* 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);
}
#endif /* SR */
}
if (s >= 0) {
(void) close(s);
s = -1;
}
#if SR
if (v_circuit == 0)
if (gotsomewhere == 0)
return NO_RESPONSE; /* no nameservers found */
else
return TIME_OUT; /* no answer obtained */
else
if (errno == ECONNREFUSED)
return NO_RESPONSE;
else
return ERROR;
#else
if (v_circuit == 0)
if (gotsomewhere == 0)
errno = ECONNREFUSED; /* no nameservers found */
else
errno = ETIMEDOUT; /* no answer obtained */
else
errno = terrno;
return (-1);
#endif
}
/*
* This routine is for closing the socket if a virtual circuit is used and
* the program wants to close it.
*
* Called from the interrupt handler.
*/
SendRequest_close()
{
if (s != -1) {
(void) close(s);
s = -1;
}
}