xref: /csrg-svn/lib/libc/net/res_send.c (revision 18548)

#ifndef lint
static char sccsid[] = "@(#)res_send.c	4.4 (Berkeley) 04/01/85";
#endif

/*
 * Copyright (c) 1985 Regents of the University of California
 *	All Rights Reserved
 */

/*
 * Send query to name server and wait for reply.
 */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <errno.h>
#include <nameser.h>
#include <resolv.h>

extern int errno;

res_send(buf, buflen, answer, anslen)
	char *buf;
	int buflen;
	char *answer;
	int anslen;
{
	register int n;
	int s, retry, v_circuit, resplen;
	u_short id, len;
	char *cp;
	int dsmask;
	struct timeval timeout;
	HEADER *hp = (HEADER *) buf;
	HEADER *anhp = (HEADER *) answer;

	if (_res.options & RES_DEBUG) {
		printf("res_send()\n");
		p_query(buf);
	}
	if (!(_res.options & RES_INIT))
		res_init();
	s = -1;
	v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
	id = hp->id;
	/*
	 * Send request, RETRY times, or until successful
	 */
	for (retry = _res.retry; --retry >= 0; ) {
		if (v_circuit) {
			/*
			 * Use virtual circuit.
			 */
			if (s < 0)
				s = socket(AF_INET, SOCK_STREAM, 0);
			if (connect(s, &_res.nsaddr, sizeof(_res.nsaddr)) < 0) {
				if (_res.options & RES_DEBUG)
					printf("connect failed %d\n", errno);
				(void) close(s);
				s = -1;
				continue;
			}
			/*
			 * Send length & message
			 */
			len = htons(buflen);
			if (write(s, &len, sizeof(len)) != sizeof(len) ||
			    write(s, buf, buflen) != buflen) {
				if (_res.options & RES_DEBUG)
					printf("write failed %d\n", errno);
				(void) close(s);
				s = -1;
				continue;
			}
			/*
			 * Receive length & response
			 */
			cp = answer;
			len = sizeof(short);
			while (len > 0 && (n = read(s, cp, len)) > 0) {
				cp += n;
				len -= n;
			}
			if (n <= 0) {
				if (_res.options & RES_DEBUG)
					printf("read failed %d\n", errno);
				(void) close(s);
				s = -1;
				continue;
			}
			cp = answer;
			resplen = len = ntohs(*(short *)cp);
			while (len > 0 && (n = read(s, cp, len)) > 0) {
				cp += n;
				len -= n;
			}
			if (n <= 0) {
				if (_res.options & RES_DEBUG)
					printf("read failed %d\n", errno);
				(void) close(s);
				s = -1;
				continue;
			}
		} else {
			/*
			 * Use datagrams.
			 */
			if (s < 0)
				s = socket(AF_INET, SOCK_DGRAM, 0);
			if (sendto(s, buf, buflen, 0, &_res.nsaddr,
			    sizeof(_res.nsaddr)) != buflen) {
				if (_res.options & RES_DEBUG)
					printf("sendto errno = %d\n", errno);
			}
			/*
			 * Wait for reply
			 */
			timeout.tv_sec = _res.retrans;
			timeout.tv_usec = 0;
			dsmask = 1 << s;
			n = select(s+1, &dsmask, 0, 0, &timeout);
			if (n < 0) {
				if (_res.options & RES_DEBUG)
					printf("select errno = %d\n", errno);
				continue;
			}
			if (n == 0) {
				/*
				 * timeout
				 */
				if (_res.options & RES_DEBUG)
					printf("timeout\n");
				continue;
			}
			if ((resplen = recvfrom(s, answer, anslen,
			    0, 0, 0)) <= 0) {
				if (_res.options & RES_DEBUG)
					printf("recvfrom, errno=%d\n", errno);
				continue;
			}
			if (id != anhp->id) {
				/*
				 * response from old query, ignore it
				 */
				if (_res.options & RES_DEBUG) {
					printf("old answer:\n");
					p_query(answer);
				}
				continue;
			}
			if (!(_res.options & RES_IGNTC) && anhp->tc) {
				/*
				 * get rest of answer
				 */
				if (_res.options & RES_DEBUG)
					printf("truncated answer\n");
				(void) close(s);
				s = -1;
				retry = _res.retry;
				v_circuit = 1;
				continue;
			}
		}
		if (_res.options & RES_DEBUG) {
			printf("got answer:\n");
			p_query(answer);
		}
		return (resplen);
	}
	return (-1);
}