usr/src/lib/libc/net/res_send.c

/*
 * Copyright (c) 1985 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_send.c	6.19 (Berkeley) %G%";
#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 <stdio.h>
#include <errno.h>
#include <arpa/nameser.h>
#include <resolv.h>

extern int errno;

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

#define KEEPOPEN (RES_USEVC|RES_STAYOPEN)

res_send(buf, buflen, answer, anslen)
	char *buf;
	int buflen;
	char *answer;
	int anslen;
{
	register int n;
	int retry, v_circuit, resplen, ns;
	int gotsomewhere = 0, connected = 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];

#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);
		}
	v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
	id = hp->id;
	/*
	 * Send request, RETRY times, or until successful
	 */
	for (retry = _res.retry; retry > 0; retry--) {
	   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
		if (v_circuit) {
			int truncated = 0;

			/*
			 * Use virtual circuit.
			 */
			if (s < 0) {
				s = socket(AF_INET, SOCK_STREAM, 0);
				if (s < 0) {
					terrno = errno;
#ifdef DEBUG
					if (_res.options & RES_DEBUG)
					    perror("socket failed");
#endif DEBUG
					continue;
				}
				if (connect(s, &(_res.nsaddr_list[ns]),
				   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;
				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	BSD >= 43
			if (_res.nscount == 1 || retry == _res.retry) {
				/*
				 * 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
#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;
			}

			/*
			 * Wait for reply
			 */
			timeout.tv_sec = (_res.retrans << (_res.retry - retry))
				/ _res.nscount;
			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\n");
#endif DEBUG
				/*
				 * Disconnect if we want to listen
				 * for responses from more than one server.
				 */
				if (_res.nscount > 1 && connected) {
					(void) connect(s, &no_addr,
					    sizeof(no_addr));
					connected = 0;
				}
				gotsomewhere = 1;
				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
				 */
#ifdef DEBUG
				if (_res.options & RES_DEBUG) {
					printf("old answer:\n");
					p_query(answer);
				}
#endif DEBUG
				goto wait;
			}
			if (!(_res.options & RES_IGNTC) && anhp->tc) {
				/*
				 * get rest of answer
				 */
#ifdef DEBUG
				if (_res.options & RES_DEBUG)
					printf("truncated answer\n");
#endif DEBUG
				(void) close(s);
				s = -1;
				/*
				 * retry decremented on continue
				 * to desired starting value
				 */
				retry = _res.retry + 1;
				v_circuit = 1;
				continue;
			}
		}
#ifdef DEBUG
		if (_res.options & RES_DEBUG) {
			printf("got answer:\n");
			p_query(answer);
		}
#endif DEBUG
		/*
		 * We are going to 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 ((_res.options & KEEPOPEN) == KEEPOPEN && ns == 0) {
			return (resplen);
		} else {
			(void) close(s);
			s = -1;
			return (resplen);
		}
	   }
	}
	if (s >= 0) {
		(void) close(s);
		s = -1;
	}
	if (v_circuit == 0)
		if (gotsomewhere == 0)
			errno = ECONNREFUSED;
		else
			errno = ETIMEDOUT;
	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;
	}
}
Commit	Line	Data
	1	/*
	2	* Copyright (c) 1985 Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms are permitted
	6	* provided that this notice is preserved and that due credit is given
	7	* to the University of California at Berkeley. The name of the University
	8	* may not be used to endorse or promote products derived from this
	9	* software without specific prior written permission. This software
	10	* is provided ``as is'' without express or implied warranty.
	11	*/
	12
	13	#if defined(LIBC_SCCS) && !defined(lint)
	14	static char sccsid[] = "@(#)res_send.c 6.19 (Berkeley) %G%";
	15	#endif /* LIBC_SCCS and not lint */
	16
	17	/*
	18	* Send query to name server and wait for reply.
	19	*/
	20
	21	#include <sys/param.h>
	22	#include <sys/time.h>
	23	#include <sys/socket.h>
	24	#include <sys/uio.h>
	25	#include <netinet/in.h>
	26	#include <stdio.h>
	27	#include <errno.h>
	28	#include <arpa/nameser.h>
	29	#include <resolv.h>
	30
	31	extern int errno;
	32
	33	static int s = -1; /* socket used for communications */
	34	static struct sockaddr no_addr;
	35
	36
	37	#ifndef FD_SET
	38	#define NFDBITS 32
	39	#define FD_SETSIZE 32
	40	#define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] \|= (1 << ((n) % NFDBITS)))
	41	#define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
	42	#define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
	43	#define FD_ZERO(p) bzero((char )(p), sizeof((p)))
	44	#endif
	45
	46	#define KEEPOPEN (RES_USEVC\|RES_STAYOPEN)
	47
	48	res_send(buf, buflen, answer, anslen)
	49	char *buf;
	50	int buflen;
	51	char *answer;
	52	int anslen;
	53	{
	54	register int n;
	55	int retry, v_circuit, resplen, ns;
	56	int gotsomewhere = 0, connected = 0;
	57	u_short id, len;
	58	char *cp;
	59	fd_set dsmask;
	60	struct timeval timeout;
	61	HEADER hp = (HEADER ) buf;
	62	HEADER anhp = (HEADER ) answer;
	63	struct iovec iov[2];
	64	int terrno = ETIMEDOUT;
	65	char junk[512];
	66
	67	#ifdef DEBUG
	68	if (_res.options & RES_DEBUG) {
	69	printf("res_send()\n");
	70	p_query(buf);
	71	}
	72	#endif DEBUG
	73	if (!(_res.options & RES_INIT))
	74	if (res_init() == -1) {
	75	return(-1);
	76	}
	77	v_circuit = (_res.options & RES_USEVC) \|\| buflen > PACKETSZ;
	78	id = hp->id;
	79	/*
	80	* Send request, RETRY times, or until successful
	81	*/
	82	for (retry = _res.retry; retry > 0; retry--) {
	83	for (ns = 0; ns < _res.nscount; ns++) {
	84	#ifdef DEBUG
	85	if (_res.options & RES_DEBUG)
	86	printf("Querying server (# %d) address = %s\n", ns+1,
	87	inet_ntoa(_res.nsaddr_list[ns].sin_addr));
	88	#endif DEBUG
	89	if (v_circuit) {
	90	int truncated = 0;
	91
	92	/*
	93	* Use virtual circuit.
	94	*/
	95	if (s < 0) {
	96	s = socket(AF_INET, SOCK_STREAM, 0);
	97	if (s < 0) {
	98	terrno = errno;
	99	#ifdef DEBUG
	100	if (_res.options & RES_DEBUG)
	101	perror("socket failed");
	102	#endif DEBUG
	103	continue;
	104	}
	105	if (connect(s, &(_res.nsaddr_list[ns]),
	106	sizeof(struct sockaddr)) < 0) {
	107	terrno = errno;
	108	#ifdef DEBUG
	109	if (_res.options & RES_DEBUG)
	110	perror("connect failed");
	111	#endif DEBUG
	112	(void) close(s);
	113	s = -1;
	114	continue;
	115	}
	116	}
	117	/*
	118	* Send length & message
	119	*/
	120	len = htons((u_short)buflen);
	121	iov[0].iov_base = (caddr_t)&len;
	122	iov[0].iov_len = sizeof(len);
	123	iov[1].iov_base = buf;
	124	iov[1].iov_len = buflen;
	125	if (writev(s, iov, 2) != sizeof(len) + buflen) {
	126	terrno = errno;
	127	#ifdef DEBUG
	128	if (_res.options & RES_DEBUG)
	129	perror("write failed");
	130	#endif DEBUG
	131	(void) close(s);
	132	s = -1;
	133	continue;
	134	}
	135	/*
	136	* Receive length & response
	137	*/
	138	cp = answer;
	139	len = sizeof(short);
	140	while (len != 0 &&
	141	(n = read(s, (char *)cp, (int)len)) > 0) {
	142	cp += n;
	143	len -= n;
	144	}
	145	if (n <= 0) {
	146	terrno = errno;
	147	#ifdef DEBUG
	148	if (_res.options & RES_DEBUG)
	149	perror("read failed");
	150	#endif DEBUG
	151	(void) close(s);
	152	s = -1;
	153	continue;
	154	}
	155	cp = answer;
	156	if ((resplen = ntohs((u_short )cp)) > anslen) {
	157	#ifdef DEBUG
	158	if (_res.options & RES_DEBUG)
	159	fprintf(stderr, "response truncated\n");
	160	#endif DEBUG
	161	len = anslen;
	162	truncated = 1;
	163	} else
	164	len = resplen;
	165	while (len != 0 &&
	166	(n = read(s, (char *)cp, (int)len)) > 0) {
	167	cp += n;
	168	len -= n;
	169	}
	170	if (n <= 0) {
	171	terrno = errno;
	172	#ifdef DEBUG
	173	if (_res.options & RES_DEBUG)
	174	perror("read failed");
	175	#endif DEBUG
	176	(void) close(s);
	177	s = -1;
	178	continue;
	179	}
	180	if (truncated) {
	181	/*
	182	* Flush rest of answer
	183	* so connection stays in synch.
	184	*/
	185	anhp->tc = 1;
	186	len = resplen - anslen;
	187	while (len != 0) {
	188	n = (len > sizeof(junk) ?
	189	sizeof(junk) : len);
	190	if ((n = read(s, junk, n)) > 0)
	191	len -= n;
	192	else
	193	break;
	194	}
	195	}
	196	} else {
	197	/*
	198	* Use datagrams.
	199	*/
	200	if (s < 0)
	201	s = socket(AF_INET, SOCK_DGRAM, 0);
	202	#if BSD >= 43
	203	if (_res.nscount == 1 \|\| retry == _res.retry) {
	204	/*
	205	* Don't use connect if we might
	206	* still receive a response
	207	* from another server.
	208	*/
	209	if (connected == 0) {
	210	if (connect(s, &_res.nsaddr_list[ns],
	211	sizeof(struct sockaddr)) < 0) {
	212	#ifdef DEBUG
	213	if (_res.options & RES_DEBUG)
	214	perror("connect");
	215	#endif DEBUG
	216	continue;
	217	}
	218	connected = 1;
	219	}
	220	if (send(s, buf, buflen, 0) != buflen) {
	221	#ifdef DEBUG
	222	if (_res.options & RES_DEBUG)
	223	perror("send");
	224	#endif DEBUG
	225	continue;
	226	}
	227	} else
	228	#endif BSD
	229	if (sendto(s, buf, buflen, 0, &_res.nsaddr_list[ns],
	230	sizeof(struct sockaddr)) != buflen) {
	231	#ifdef DEBUG
	232	if (_res.options & RES_DEBUG)
	233	perror("sendto");
	234	#endif DEBUG
	235	continue;
	236	}
	237
	238	/*
	239	* Wait for reply
	240	*/
	241	timeout.tv_sec = (_res.retrans << (_res.retry - retry))
	242	/ _res.nscount;
	243	if (timeout.tv_sec <= 0)
	244	timeout.tv_sec = 1;
	245	timeout.tv_usec = 0;
	246	wait:
	247	FD_ZERO(&dsmask);
	248	FD_SET(s, &dsmask);
	249	n = select(s+1, &dsmask, (fd_set *)NULL,
	250	(fd_set *)NULL, &timeout);
	251	if (n < 0) {
	252	#ifdef DEBUG
	253	if (_res.options & RES_DEBUG)
	254	perror("select");
	255	#endif DEBUG
	256	continue;
	257	}
	258	if (n == 0) {
	259	/*
	260	* timeout
	261	*/
	262	#ifdef DEBUG
	263	if (_res.options & RES_DEBUG)
	264	printf("timeout\n");
	265	#endif DEBUG
	266	/*
	267	* Disconnect if we want to listen
	268	* for responses from more than one server.
	269	*/
	270	if (_res.nscount > 1 && connected) {
	271	(void) connect(s, &no_addr,
	272	sizeof(no_addr));
	273	connected = 0;
	274	}
	275	gotsomewhere = 1;
	276	continue;
	277	}
	278	if ((resplen = recv(s, answer, anslen, 0)) <= 0) {
	279	#ifdef DEBUG
	280	if (_res.options & RES_DEBUG)
	281	perror("recvfrom");
	282	#endif DEBUG
	283	continue;
	284	}
	285	gotsomewhere = 1;
	286	if (id != anhp->id) {
	287	/*
	288	* response from old query, ignore it
	289	*/
	290	#ifdef DEBUG
	291	if (_res.options & RES_DEBUG) {
	292	printf("old answer:\n");
	293	p_query(answer);
	294	}
	295	#endif DEBUG
	296	goto wait;
	297	}
	298	if (!(_res.options & RES_IGNTC) && anhp->tc) {
	299	/*
	300	* get rest of answer
	301	*/
	302	#ifdef DEBUG
	303	if (_res.options & RES_DEBUG)
	304	printf("truncated answer\n");
	305	#endif DEBUG
	306	(void) close(s);
	307	s = -1;
	308	/*
	309	* retry decremented on continue
	310	* to desired starting value
	311	*/
	312	retry = _res.retry + 1;
	313	v_circuit = 1;
	314	continue;
	315	}
	316	}
	317	#ifdef DEBUG
	318	if (_res.options & RES_DEBUG) {
	319	printf("got answer:\n");
	320	p_query(answer);
	321	}
	322	#endif DEBUG
	323	/*
	324	* We are going to assume that the first server is preferred
	325	* over the rest (i.e. it is on the local machine) and only
	326	* keep that one open.
	327	*/
	328	if ((_res.options & KEEPOPEN) == KEEPOPEN && ns == 0) {
	329	return (resplen);
	330	} else {
	331	(void) close(s);
	332	s = -1;
	333	return (resplen);
	334	}
	335	}
	336	}
	337	if (s >= 0) {
	338	(void) close(s);
	339	s = -1;
	340	}
	341	if (v_circuit == 0)
	342	if (gotsomewhere == 0)
	343	errno = ECONNREFUSED;
	344	else
	345	errno = ETIMEDOUT;
	346	else
	347	errno = terrno;
	348	return (-1);
	349	}
	350
	351	/*
	352	* This routine is for closing the socket if a virtual circuit is used and
	353	* the program wants to close it. This provides support for endhostent()
	354	* which expects to close the socket.
	355	*
	356	* This routine is not expected to be user visible.
	357	*/
	358	_res_close()
	359	{
	360	if (s != -1) {
	361	(void) close(s);
	362	s = -1;
	363	}
	364	}