res_send.c

bind 9.3结合mysql数据库

#ifdef HAVE_SA_LEN
	/* There are people do not set sa_len.  Be forgiving to them. */
	if (sa->sa_len)
		return (sa->sa_len);
#endif

	if (sa->sa_family == AF_INET)
		return (sizeof(struct sockaddr_in));
	else if (sa->sa_family == AF_INET6)
		return (sizeof(struct sockaddr_in6));
	else
		return (0);	/* unknown, die on connect */
}

/*
 * pick appropriate nsaddr_list for use.  see res_init() for initialization.
 */
static struct sockaddr *
get_nsaddr(statp, n)
	res_state statp;
	size_t n;
{

	if (!statp->nsaddr_list[n].sin_family && EXT(statp).ext) {
		/*
		 * - EXT(statp).ext->nsaddrs[n] holds an address that is larger
		 *   than struct sockaddr, and
		 * - user code did not update statp->nsaddr_list[n].
		 */
		return (struct sockaddr *)(void *)&EXT(statp).ext->nsaddrs[n];
	} else {
		/*
		 * - user code updated statp->nsaddr_list[n], or
		 * - statp->nsaddr_list[n] has the same content as
		 *   EXT(statp).ext->nsaddrs[n].
		 */
		return (struct sockaddr *)(void *)&statp->nsaddr_list[n];
	}
}

static int
send_vc(res_state statp,
	const u_char *buf, int buflen, u_char *ans, int anssiz,
	int *terrno, int ns)
{
	const HEADER *hp = (const HEADER *) buf;
	HEADER *anhp = (HEADER *) ans;
	struct sockaddr *nsap;
	int nsaplen;
	int truncating, connreset, resplen, n;
	struct iovec iov[2];
	u_short len;
	u_char *cp;
	void *tmp;

	nsap = get_nsaddr(statp, ns);
	nsaplen = get_salen(nsap);

	connreset = 0;
 same_ns:
	truncating = 0;

	/* Are we still talking to whom we want to talk to? */
	if (statp->_vcsock >= 0 && (statp->_flags & RES_F_VC) != 0) {
		struct sockaddr_storage peer;
		ISC_SOCKLEN_T size = sizeof peer;

		if (getpeername(statp->_vcsock,
				(struct sockaddr *)&peer, &size) < 0 ||
		    !sock_eq((struct sockaddr *)&peer, nsap)) {
			res_nclose(statp);
			statp->_flags &= ~RES_F_VC;
		}
	}

	if (statp->_vcsock < 0 || (statp->_flags & RES_F_VC) == 0) {
		if (statp->_vcsock >= 0)
			res_nclose(statp);

		statp->_vcsock = socket(nsap->sa_family, SOCK_STREAM, 0);
		if (statp->_vcsock > highestFD) {
			res_nclose(statp);
			errno = ENOTSOCK;
		}
		if (statp->_vcsock < 0) {
			switch (errno) {
			case EPROTONOSUPPORT:
#ifdef EPFNOSUPPORT
			case EPFNOSUPPORT:
#endif
			case EAFNOSUPPORT:
				Perror(statp, stderr, "socket(vc)", errno);
				return (0);
			default:
				*terrno = errno;
				Perror(statp, stderr, "socket(vc)", errno);
				return (-1);
			}
		}
		errno = 0;
		if (connect(statp->_vcsock, nsap, nsaplen) < 0) {
			*terrno = errno;
			Aerror(statp, stderr, "connect/vc", errno, nsap,
			    nsaplen);
			res_nclose(statp);
			return (0);
		}
		statp->_flags |= RES_F_VC;
	}

	/*
	 * Send length & message
	 */
	ns_put16((u_short)buflen, (u_char*)&len);
	iov[0] = evConsIovec(&len, INT16SZ);
	DE_CONST(buf, tmp);
	iov[1] = evConsIovec(tmp, buflen);
	if (writev(statp->_vcsock, iov, 2) != (INT16SZ + buflen)) {
		*terrno = errno;
		Perror(statp, stderr, "write failed", errno);
		res_nclose(statp);
		return (0);
	}
	/*
	 * Receive length & response
	 */
 read_len:
	cp = ans;
	len = INT16SZ;
	while ((n = read(statp->_vcsock, (char *)cp, (int)len)) > 0) {
		cp += n;
		if ((len -= n) == 0)
			break;
	}
	if (n <= 0) {
		*terrno = errno;
		Perror(statp, stderr, "read failed", errno);
		res_nclose(statp);
		/*
		 * 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_nclose(statp);
			goto same_ns;
		}
		res_nclose(statp);
		return (0);
	}
	resplen = ns_get16(ans);
	if (resplen > anssiz) {
		Dprint(statp->options & RES_DEBUG,
		       (stdout, ";; response truncated\n")
		       );
		truncating = 1;
		len = anssiz;
	} else
		len = resplen;
	if (len < HFIXEDSZ) {
		/*
		 * Undersized message.
		 */
		Dprint(statp->options & RES_DEBUG,
		       (stdout, ";; undersized: %d\n", len));
		*terrno = EMSGSIZE;
		res_nclose(statp);
		return (0);
	}
	cp = ans;
	while (len != 0 && (n = read(statp->_vcsock, (char *)cp, (int)len)) > 0){
		cp += n;
		len -= n;
	}
	if (n <= 0) {
		*terrno = errno;
		Perror(statp, stderr, "read(vc)", errno);
		res_nclose(statp);
		return (0);
	}
	if (truncating) {
		/*
		 * Flush rest of answer so connection stays in synch.
		 */
		anhp->tc = 1;
		len = resplen - anssiz;
		while (len != 0) {
			char junk[PACKETSZ];

			n = read(statp->_vcsock, junk,
				 (len > sizeof junk) ? sizeof junk : len);
			if (n > 0)
				len -= n;
			else
				break;
		}
	}
	/*
	 * If 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, then drop the packet and
	 * wait for the correct one.
	 */
	if (hp->id != anhp->id) {
		DprintQ((statp->options & RES_DEBUG) ||
			(statp->pfcode & RES_PRF_REPLY),
			(stdout, ";; old answer (unexpected):\n"),
			ans, (resplen > anssiz) ? anssiz: resplen);
		goto read_len;
	}

	/*
	 * All is well, or the error is fatal.  Signal that the
	 * next nameserver ought not be tried.
	 */
	return (resplen);
}

static int
send_dg(res_state statp,
	const u_char *buf, int buflen, u_char *ans, int anssiz,
	int *terrno, int ns, int *v_circuit, int *gotsomewhere)
{
	const HEADER *hp = (const HEADER *) buf;
	HEADER *anhp = (HEADER *) ans;
	const struct sockaddr *nsap;
	int nsaplen;
	struct timespec now, timeout, finish;
	fd_set dsmask;
	struct sockaddr_storage from;
	ISC_SOCKLEN_T fromlen;
	int resplen, seconds, n, s;

	nsap = get_nsaddr(statp, ns);
	nsaplen = get_salen(nsap);
	if (EXT(statp).nssocks[ns] == -1) {
		EXT(statp).nssocks[ns] = socket(nsap->sa_family, SOCK_DGRAM, 0);
		if (EXT(statp).nssocks[ns] > highestFD) {
			res_nclose(statp);
			errno = ENOTSOCK;
		}
		if (EXT(statp).nssocks[ns] < 0) {
			switch (errno) {
			case EPROTONOSUPPORT:
#ifdef EPFNOSUPPORT
			case EPFNOSUPPORT:
#endif
			case EAFNOSUPPORT:
				Perror(statp, stderr, "socket(dg)", errno);
				return (0);
			default:
				*terrno = errno;
				Perror(statp, stderr, "socket(dg)", errno);
				return (-1);
			}
		}
#ifndef CANNOT_CONNECT_DGRAM
		/*
		 * 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 (connect(EXT(statp).nssocks[ns], nsap, nsaplen) < 0) {
			Aerror(statp, stderr, "connect(dg)", errno, nsap,
			    nsaplen);
			res_nclose(statp);
			return (0);
		}
#endif /* !CANNOT_CONNECT_DGRAM */
		Dprint(statp->options & RES_DEBUG,
		       (stdout, ";; new DG socket\n"))
	}
	s = EXT(statp).nssocks[ns];
#ifndef CANNOT_CONNECT_DGRAM
	if (send(s, (const char*)buf, buflen, 0) != buflen) {
		Perror(statp, stderr, "send", errno);
		res_nclose(statp);
		return (0);
	}
#else /* !CANNOT_CONNECT_DGRAM */
	if (sendto(s, (const char*)buf, buflen, 0, nsap, nsaplen) != buflen)
	{
		Aerror(statp, stderr, "sendto", errno, nsap, nsaplen);
		res_nclose(statp);
		return (0);
	}
#endif /* !CANNOT_CONNECT_DGRAM */

	/*
	 * Wait for reply.
	 */
	seconds = (statp->retrans << ns);
	if (ns > 0)
		seconds /= statp->nscount;
	if (seconds <= 0)
		seconds = 1;
	now = evNowTime();
	timeout = evConsTime(seconds, 0);
	finish = evAddTime(now, timeout);
	goto nonow;
 wait:
	now = evNowTime();
 nonow:
	FD_ZERO(&dsmask);
	FD_SET(s, &dsmask);
	if (evCmpTime(finish, now) > 0)
		timeout = evSubTime(finish, now);
	else
		timeout = evConsTime(0, 0);
	n = pselect(s + 1, &dsmask, NULL, NULL, &timeout, NULL);
	if (n == 0) {
		Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n"));
		*gotsomewhere = 1;
		return (0);
	}
	if (n < 0) {
		if (errno == EINTR)
			goto wait;
		Perror(statp, stderr, "select", errno);
		res_nclose(statp);
		return (0);
	}
	errno = 0;
	fromlen = sizeof(from);
	resplen = recvfrom(s, (char*)ans, anssiz,0,
			   (struct sockaddr *)&from, &fromlen);
	if (resplen <= 0) {
		Perror(statp, stderr, "recvfrom", errno);
		res_nclose(statp);
		return (0);
	}
	*gotsomewhere = 1;
	if (resplen < HFIXEDSZ) {
		/*
		 * Undersized message.
		 */
		Dprint(statp->options & RES_DEBUG,
		       (stdout, ";; undersized: %d\n",
			resplen));
		*terrno = EMSGSIZE;
		res_nclose(statp);
		return (0);
	}
	if (hp->id != anhp->id) {
		/*
		 * response from old query, ignore it.
		 * XXX - potential security hazard could
		 *	 be detected here.
		 */
		DprintQ((statp->options & RES_DEBUG) ||
			(statp->pfcode & RES_PRF_REPLY),
			(stdout, ";; old answer:\n"),
			ans, (resplen > anssiz) ? anssiz : resplen);
		goto wait;
	}
	if (!(statp->options & RES_INSECURE1) &&
	    !res_ourserver_p(statp, (struct sockaddr *)&from)) {
		/*
		 * response from wrong server? ignore it.
		 * XXX - potential security hazard could
		 *	 be detected here.
		 */
		DprintQ((statp->options & RES_DEBUG) ||
			(statp->pfcode & RES_PRF_REPLY),
			(stdout, ";; not our server:\n"),
			ans, (resplen > anssiz) ? anssiz : resplen);
		goto wait;
	}
#ifdef RES_USE_EDNS0
	if (anhp->rcode == FORMERR && (statp->options & RES_USE_EDNS0) != 0U) {
		/*
		 * Do not retry if the server do not understand EDNS0.
		 * The case has to be captured here, as FORMERR packet do not
		 * carry query section, hence res_queriesmatch() returns 0.
		 */
		DprintQ(statp->options & RES_DEBUG,
			(stdout, "server rejected query with EDNS0:\n"),
			ans, (resplen > anssiz) ? anssiz : resplen);
		/* record the error */
		statp->_flags |= RES_F_EDNS0ERR;
		res_nclose(statp);
		return (0);
	}
#endif
	if (!(statp->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((statp->options & RES_DEBUG) ||
			(statp->pfcode & RES_PRF_REPLY),
			(stdout, ";; wrong query name:\n"),
			ans, (resplen > anssiz) ? anssiz : resplen);
		goto wait;
	}
	if (anhp->rcode == SERVFAIL ||
	    anhp->rcode == NOTIMP ||
	    anhp->rcode == REFUSED) {
		DprintQ(statp->options & RES_DEBUG,
			(stdout, "server rejected query:\n"),
			ans, (resplen > anssiz) ? anssiz : resplen);
		res_nclose(statp);
		/* don't retry if called from dig */
		if (!statp->pfcode)
			return (0);
	}
	if (!(statp->options & RES_IGNTC) && anhp->tc) {
		/*
		 * To get the rest of answer,
		 * use TCP with same server.
		 */
		Dprint(statp->options & RES_DEBUG,
		       (stdout, ";; truncated answer\n"));
		*v_circuit = 1;
		res_nclose(statp);
		return (1);
	}
	/*
	 * All is well, or the error is fatal.  Signal that the
	 * next nameserver ought not be tried.
	 */
	return (resplen);
}

static void
Aerror(const res_state statp, FILE *file, const char *string, int error,
       const struct sockaddr *address, int alen)
{
	int save = errno;
	char hbuf[NI_MAXHOST];
	char sbuf[NI_MAXSERV];

	alen = alen;

	if ((statp->options & RES_DEBUG) != 0U) {
		if (getnameinfo(address, alen, hbuf, sizeof(hbuf),
		    sbuf, sizeof(sbuf), niflags)) {
			strncpy(hbuf, "?", sizeof(hbuf) - 1);
			hbuf[sizeof(hbuf) - 1] = '\0';
			strncpy(sbuf, "?", sizeof(sbuf) - 1);
			sbuf[sizeof(sbuf) - 1] = '\0';
		}
		fprintf(file, "res_send: %s ([%s].%s): %s\n",
			string, hbuf, sbuf, strerror(error));
	}
	errno = save;
}

static void
Perror(const res_state statp, FILE *file, const char *string, int error) {
	int save = errno;

	if ((statp->options & RES_DEBUG) != 0U)
		fprintf(file, "res_send: %s: %s\n",
			string, strerror(error));
	errno = save;
}

static int
sock_eq(struct sockaddr *a, struct sockaddr *b) {
	struct sockaddr_in *a4, *b4;
	struct sockaddr_in6 *a6, *b6;

	if (a->sa_family != b->sa_family)
		return 0;
	switch (a->sa_family) {
	case AF_INET:
		a4 = (struct sockaddr_in *)a;
		b4 = (struct sockaddr_in *)b;
		return a4->sin_port == b4->sin_port &&
		    a4->sin_addr.s_addr == b4->sin_addr.s_addr;
	case AF_INET6:
		a6 = (struct sockaddr_in6 *)a;
		b6 = (struct sockaddr_in6 *)b;
		return a6->sin6_port == b6->sin6_port &&
#ifdef HAVE_SIN6_SCOPE_ID
		    a6->sin6_scope_id == b6->sin6_scope_id &&
#endif
		    IN6_ARE_ADDR_EQUAL(&a6->sin6_addr, &b6->sin6_addr);
	default:
		return 0;
	}
}

#ifdef NEED_PSELECT
/* XXX needs to move to the porting library. */
static int
pselect(int nfds, void *rfds, void *wfds, void *efds,
	struct timespec *tsp, const sigset_t *sigmask)
{
	struct timeval tv, *tvp;
	sigset_t sigs;
	int n;

	if (tsp) {
		tvp = &tv;
		tv = evTimeVal(*tsp);
	} else
		tvp = NULL;
	if (sigmask)
		sigprocmask(SIG_SETMASK, sigmask, &sigs);
	n = select(nfds, rfds, wfds, efds, tvp);
	if (sigmask)
		sigprocmask(SIG_SETMASK, &sigs, NULL);
	if (tsp)
		*tsp = evTimeSpec(tv);
	return (n);
}
#endif