name6.c

用于嵌入式Linux系统的标准C的库函数

				bp += n;
				buflen -= n;
			}
			break;
#else
			template->h_name = bp;
			*errp = NETDB_SUCCESS;
			return (template);
#endif
		case T_A:
		case T_AAAA:
			DNS_ASSERT(strcasecmp(template->h_name, bp) == 0);
			DNS_ASSERT(n == template->h_length);
			if (!haveanswer) {
				int nn;

				template->h_name = bp;
				nn = strlen(bp) + 1;	/* for the \0 */
				bp += nn;
				buflen -= nn;
			}
#ifdef ALIGN
			bp = (char *)ALIGN(bp);
#else
			bp = (char *)(bp);
#endif

			DNS_FATAL(bp + n < &hostbuf[sizeof hostbuf]);
			DNS_ASSERT(hap < &h_addr_ptrs[MAXADDRS-1]);
#ifdef FILTER_V4MAPPED
			if (type == T_AAAA) {
				struct in6_addr in6;
				memcpy(&in6, cp, sizeof(in6));
				DNS_ASSERT(IN6_IS_ADDR_V4MAPPED(&in6) == 0);
			}
#endif
			bcopy(cp, *hap++ = bp, n);
			bp += n;
			buflen -= n;
			cp += n;
			if (cp != erdata) {
				*errp = NO_RECOVERY;
				return (NULL);
			}
			break;
		default:
			abort();
		}
		if (!had_error)
			haveanswer++;
	}
	if (haveanswer) {
		*ap = NULL;
		*hap = NULL;
		if (!template->h_name) {
			n = strlen(qname) + 1;	/* for the \0 */
			if (n > buflen || n >= MAXHOSTNAMELEN)
				goto no_recovery;
			strcpy(bp, qname);
			template->h_name = bp;
			bp += n;
			buflen -= n;
		}
		*errp = NETDB_SUCCESS;
		return (template);
	}
 no_recovery:
	*errp = NO_RECOVERY;
	return (NULL);

#undef BOUNDED_INCR
#undef BOUNDS_CHECK
#undef DNS_ASSERT
#undef DNS_FATAL
}

/* res_search() variant with multiple query support. */
static struct hostent *
_res_search_multi(name, rtl, errp)
	const char *name;	/* domain name */
	struct	__res_type_list *rtl; /* list of query types */
	int *errp;
{
	const char *cp, * const *domain;
	struct hostent *hp0 = NULL, *hp;
	struct hostent hpbuf;
	u_int dots;
	int trailing_dot, ret, saved_herrno;
	int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
	struct __res_type_list *rtl0 = rtl;
	querybuf buf;

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		*errp = NETDB_INTERNAL;
		return (NULL);
	}
	dots = 0;
	for (cp = name; *cp; cp++)
		dots += (*cp == '.');
	trailing_dot = 0;
	if (cp > name && *--cp == '.')
		trailing_dot++;

	/* If there aren't any dots, it could be a user-level alias */
	if (!dots && (cp = hostalias(name)) != NULL) {
		for(rtl = rtl0; rtl != NULL;
		    rtl = rtl->rtl_entry) {
			ret = res_query(cp, C_IN, rtl->rtl_type, buf.buf,
					     sizeof(buf.buf));
			if (ret > 0) {
				hpbuf.h_addrtype = (rtl->rtl_type == T_AAAA)
				    ? AF_INET6 : AF_INET;
				hpbuf.h_length = ADDRLEN(hpbuf.h_addrtype);
				hp = getanswer(&buf, ret, name, rtl->rtl_type,
						    &hpbuf, errp);
				if (!hp)
					continue;
				hp = _hpcopy(&hpbuf, errp);
				hp0 = _hpmerge(hp0, hp, errp);
			}
		}
		return (hp0);
	}

	/*
	 * If there are dots in the name already, let's just give it a try
	 * 'as is'.  The threshold can be set with the "ndots" option.
	 */
	saved_herrno = -1;
	if (dots >= _res.ndots) {
		for(rtl = rtl0; rtl != NULL;
		    rtl = rtl->rtl_entry) {
			ret = res_querydomain(name, NULL, C_IN, rtl->rtl_type,
					      buf.buf, sizeof(buf.buf));
			if (ret > 0) {
				hpbuf.h_addrtype = (rtl->rtl_type == T_AAAA)
				    ? AF_INET6 : AF_INET;
				hpbuf.h_length = ADDRLEN(hpbuf.h_addrtype);
				hp = getanswer(&buf, ret, name, rtl->rtl_type,
						    &hpbuf, errp);
				if (!hp)
					continue;
				hp = _hpcopy(&hpbuf, errp);
				hp0 = _hpmerge(hp0, hp, errp);
			}
		}
		if (hp0 != NULL)
			return (hp0);
		saved_herrno = *errp;
		tried_as_is++;
	}

	/*
	 * We do at least one level of search if
	 *	- there is no dot and RES_DEFNAME is set, or
	 *	- there is at least one dot, there is no trailing dot,
	 *	  and RES_DNSRCH is set.
	 */
	if ((!dots && (_res.options & RES_DEFNAMES)) ||
	    (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {
		int done = 0;

		for (domain = (const char * const *)_res.dnsrch;
		     *domain && !done;
		     domain++) {

			for(rtl = rtl0; rtl != NULL;
			    rtl = rtl->rtl_entry) {
				ret = res_querydomain(name, *domain, C_IN,
						      rtl->rtl_type,
						      buf.buf, sizeof(buf.buf));
				if (ret > 0) {
					hpbuf.h_addrtype = (rtl->rtl_type == T_AAAA)
					    ? AF_INET6 : AF_INET;
					hpbuf.h_length = ADDRLEN(hpbuf.h_addrtype);
					hp = getanswer(&buf, ret, name,
					    rtl->rtl_type, &hpbuf, errp);
					if (!hp)
						continue;
					hp = _hpcopy(&hpbuf, errp);
					hp0 = _hpmerge(hp0, hp, errp);
				}
			}
			if (hp0 != NULL)
				return (hp0);

			/*
			 * If no server present, give up.
			 * If name isn't found in this domain,
			 * keep trying higher domains in the search list
			 * (if that's enabled).
			 * On a NO_DATA error, keep trying, otherwise
			 * a wildcard entry of another type could keep us
			 * from finding this entry higher in the domain.
			 * If we get some other error (negative answer or
			 * server failure), then stop searching up,
			 * but try the input name below in case it's
			 * fully-qualified.
			 */
			if (errno == ECONNREFUSED) {
				*errp = TRY_AGAIN;
				return (NULL);
			}

			switch (*errp) {
			case NO_DATA:
				got_nodata++;
				/* FALLTHROUGH */
			case HOST_NOT_FOUND:
				/* keep trying */
				break;
			case TRY_AGAIN:
				if (buf.hdr.rcode == SERVFAIL) {
					/* try next search element, if any */
					got_servfail++;
					break;
				}
				/* FALLTHROUGH */
			default:
				/* anything else implies that we're done */
				done++;
			}

			/* if we got here for some reason other than DNSRCH,
			 * we only wanted one iteration of the loop, so stop.
			 */
			if (!(_res.options & RES_DNSRCH))
				done++;
		}
	}

	/*
	 * If we have not already tried the name "as is", do that now.
	 * note that we do this regardless of how many dots were in the
	 * name or whether it ends with a dot unless NOTLDQUERY is set.
	 */
	if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) {
		for(rtl = rtl0; rtl != NULL;
		    rtl = rtl->rtl_entry) {
			ret = res_querydomain(name, NULL, C_IN, rtl->rtl_type,
					      buf.buf, sizeof(buf.buf));
			if (ret > 0) {
				hpbuf.h_addrtype = (rtl->rtl_type == T_AAAA)
				    ? AF_INET6 : AF_INET;
				hpbuf.h_length = ADDRLEN(hpbuf.h_addrtype);
				hp = getanswer(&buf, ret, name, rtl->rtl_type,
				    &hpbuf, errp);
				if (!hp)
					continue;
				hp = _hpcopy(&hpbuf, errp);
				hp0 = _hpmerge(hp0, hp, errp);
			}
		}
		if (hp0 != NULL)
			return (hp0);
	}

	/* if we got here, we didn't satisfy the search.
	 * if we did an initial full query, return that query's h_errno
	 * (note that we wouldn't be here if that query had succeeded).
	 * else if we ever got a nodata, send that back as the reason.
	 * else send back meaningless h_errno, that being the one from
	 * the last DNSRCH we did.
	 */
	if (saved_herrno != -1)
		*errp = saved_herrno;
	else if (got_nodata)
		*errp = NO_DATA;
	else if (got_servfail)
		*errp = TRY_AGAIN;
	return (NULL);
}

static int
_dns_ghbyname(void *rval, void *cb_data, va_list ap)
{
	const char *name;
	int af;
	int *errp;
	res_type_list *rtl, rtl4;
#ifdef INET6
	res_type_list rtl6;
#endif

	name = va_arg(ap, const char *);
	af = va_arg(ap, int);
	errp = va_arg(ap, int *);

#ifdef INET6
	switch (af) {
	case AF_UNSPEC:
		&rtl4->rtl_entry = NULL; rtl4.rtl_type = T_A;
		&rtl6->rtl_entry = &rtl4; rtl6.rtl_type = T_AAAA;
		rtl = &rtl6;
		break;
	case AF_INET6:
		&rtl6->rtl_entry = NULL; rtl6.rtl_type = T_AAAA;
		rtl = &rtl6;
		break;
	case AF_INET:
		&rtl4->rtl_entry = NULL; rtl4.rtl_type = T_A;
		rtl = &rtl4;
		break;
	}
#else
	(&rtl4)->rtl_entry = NULL;
        rtl4.rtl_type = T_A;
	rtl = &rtl4;
#endif
	*(struct hostent **)rval = _res_search_multi(name, rtl, errp);
	return (*(struct hostent **)rval != NULL) ? NS_SUCCESS : NS_NOTFOUND;
}

static int
_dns_ghbyaddr(void *rval, void *cb_data, va_list ap)
{
	const void *addr;
	int addrlen;
	int af;
	int *errp;
	int n;
	struct hostent *hp;
	u_char c, *cp;
	char *bp;
	struct hostent hbuf;
	int na;
#ifdef INET6
	static const char hex[] = "0123456789abcdef";
#endif
	querybuf buf;
	char qbuf[MAXDNAME+1];
	char *hlist[2];

	addr = va_arg(ap, const void *);
	addrlen = va_arg(ap, int);
	af = va_arg(ap, int);
	errp = va_arg(ap, int *);

	*(struct hostent **)rval = NULL;

#ifdef INET6
	/* XXX */
	if (af == AF_INET6 && IN6_IS_ADDR_LINKLOCAL((struct in6_addr *)addr))
		return NS_NOTFOUND;
#endif

	if ((_res.options & RES_INIT) == 0) {
		if (res_init() < 0) {
			*errp = h_errno;
			return NS_UNAVAIL;
		}
	}
	memset(&hbuf, 0, sizeof(hbuf));
	hbuf.h_name = NULL;
	hbuf.h_addrtype = af;
	hbuf.h_length = addrlen;
	na = 0;

	/* XXX assumes that MAXDNAME is big enough */
	n = 0;
	bp = qbuf;
	cp = (u_char *)addr+addrlen-1;
	switch (af) {
#ifdef INET6
	case AF_INET6:
		for (; n < addrlen; n++, cp--) {
			c = *cp;
			*bp++ = hex[c & 0xf];
			*bp++ = '.';
			*bp++ = hex[c >> 4];
			*bp++ = '.';
		}
		strcpy(bp, "ip6.int");
		break;
#endif
	default:
		for (; n < addrlen; n++, cp--) {
			c = *cp;
			if (c >= 100)
				*bp++ = '0' + c / 100;
			if (c >= 10)
				*bp++ = '0' + (c % 100) / 10;
			*bp++ = '0' + c % 10;
			*bp++ = '.';
		}
		strcpy(bp, "in-addr.arpa");
		break;
	}

	n = res_query(qbuf, C_IN, T_PTR, buf.buf, sizeof buf.buf);
	if (n < 0) {
		*errp = h_errno;
		return NS_UNAVAIL;
	}
	hp = getanswer(&buf, n, qbuf, T_PTR, &hbuf, errp);
	if (!hp)
		return NS_NOTFOUND;
	hbuf.h_addrtype = af;
	hbuf.h_length = addrlen;
	hbuf.h_addr_list = hlist;
	hlist[0] = (char *)addr;
	hlist[1] = NULL;
	*(struct hostent **)rval = _hpcopy(&hbuf, errp);
	return NS_SUCCESS;
}

#if 0 // keep gcc happy
static void
_dns_shent(int stayopen)
{
	if ((_res.options & RES_INIT) == 0) {
		if (res_init() < 0)
			return;
	}
	if (stayopen)
		_res.options |= RES_STAYOPEN | RES_USEVC;
}

static void
_dns_ehent(void)
{
	_res.options &= ~(RES_STAYOPEN | RES_USEVC);
	res_close();
}
#endif

#ifdef ICMPNL

/*
 * experimental:
 *	draft-ietf-ipngwg-icmp-namelookups-02.txt
 *	ifindex is assumed to be encoded in addr.
 */
#include <sys/uio.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>

struct _icmp_host_cache {
	struct _icmp_host_cache *hc_next;
	int hc_ifindex;
	struct in6_addr hc_addr;
	char *hc_name;
};

static char *
_icmp_fqdn_query(const struct in6_addr *addr, int ifindex)
{
	int s;
	struct icmp6_filter filter;
	struct msghdr msg;
	struct cmsghdr *cmsg;
	struct in6_pktinfo *pkt;
	char cbuf[256];
	char buf[1024];
	int cc;
	struct icmp6_fqdn_query *fq;
	struct icmp6_fqdn_reply *fr;
	struct _icmp_host_cache *hc;
	struct sockaddr_in6 sin6;
	struct iovec iov;
	fd_set s_fds, fds;
	struct timeval tout;
	int len;
	char *name;
	static int pid;
	static struct _icmp_host_cache *hc_head;

	for (hc = hc_head; hc; hc = hc->hc_next) {
		if (hc->hc_ifindex == ifindex
		&&  IN6_ARE_ADDR_EQUAL(&hc->hc_addr, addr))
			return hc->hc_name;
	}

	if (pid == 0)
		pid = getpid();

	ICMP6_FILTER_SETBLOCKALL(&filter);
	ICMP6_FILTER_SETPASS(ICMP6_FQDN_REPLY, &filter);

	FD_ZERO(&s_fds);
	tout.tv_sec = 0;
	tout.tv_usec = 200000;	/*XXX: 200ms*/

	fq = (struct icmp6_fqdn_query *)buf;
	fq->icmp6_fqdn_type = ICMP6_FQDN_QUERY;
	fq->icmp6_fqdn_code = 0;
	fq->icmp6_fqdn_cksum = 0;
	fq->icmp6_fqdn_id = (u_short)pid;
	fq->icmp6_fqdn_unused = 0;
	fq->icmp6_fqdn_cookie[0] = 0;
	fq->icmp6_fqdn_cookie[1] = 0;

	memset(&sin6, 0, sizeof(sin6));
	sin6.sin6_family = AF_INET6;
	sin6.sin6_addr = *addr;

	memset(&msg, 0, sizeof(msg));
	msg.msg_name = (caddr_t)&sin6;
	msg.msg_namelen = sizeof(sin6);
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_control = NULL;
	msg.msg_controllen = 0;
	iov.iov_base = (caddr_t)buf;
	iov.iov_len = sizeof(struct icmp6_fqdn_query);

	if (ifindex) {
		msg.msg_control = cbuf;
		msg.msg_controllen = sizeof(cbuf);
		cmsg = CMSG_FIRSTHDR(&msg);
		cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
		cmsg->cmsg_level = IPPROTO_IPV6;
		cmsg->cmsg_type = IPV6_PKTINFO;
		pkt = (struct in6_pktinfo *)&cmsg[1];
		memset(&pkt->ipi6_addr, 0, sizeof(struct in6_addr));
		pkt->ipi6_ifindex = ifindex;
		cmsg = CMSG_NXTHDR(&msg, cmsg);
		msg.msg_controllen = (char *)cmsg - cbuf;
	}

	if ((s = socket(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) < 0)
		return NULL;
	(void)setsockopt(s, IPPROTO_ICMPV6, ICMP6_FILTER,
			 (char *)&filter, sizeof(filter));
	cc = _sendmsg(s, &msg, 0);
	if (cc < 0) {
		close(s);
		return NULL;
	}
	FD_SET(s, &s_fds);
	for (;;) {
		fds = s_fds;
		if (select(s + 1, &fds, NULL, NULL, &tout) <= 0) {
			close(s);
			return NULL;
		}
		len = sizeof(sin6);
		cc = _recvfrom(s, buf, sizeof(buf), 0,
			      (struct sockaddr *)&sin6, &len);
		if (cc <= 0) {
			close(s);
			return NULL;
		}
		if (cc < sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr))
			continue;
		if (!IN6_ARE_ADDR_EQUAL(addr, &sin6.sin6_addr))
			continue;
		fr = (struct icmp6_fqdn_reply *)(buf + sizeof(struct ip6_hdr));
		if (fr->icmp6_fqdn_type == ICMP6_FQDN_REPLY)
			break;
	}
	close(s);
	if (fr->icmp6_fqdn_cookie[1] != 0) {
		/* rfc1788 type */
		name = buf + sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr) + 4;
		len = (buf + cc) - name;
	} else {
		len = fr->icmp6_fqdn_namelen;
		name = fr->icmp6_fqdn_name;
	}
	if (len <= 0)
		return NULL;
	name[len] = 0;

	if ((hc = (struct _icmp_host_cache *)malloc(sizeof(*hc))) == NULL)
		return NULL;
	/* XXX: limit number of cached entries */
	hc->hc_ifindex = ifindex;
	hc->hc_addr = *addr;
	hc->hc_name = strdup(name);
	hc->hc_next = hc_head;
	hc_head = hc;
	return hc->hc_name;
}

static struct hostent *
_icmp_ghbyaddr(const void *addr, int addrlen, int af, int *errp)
{
	char *hname;
	int ifindex;
	struct in6_addr addr6;

	if (af != AF_INET6) {
		/*
		 * Note: rfc1788 defines Who Are You for IPv4,
		 * but no one implements it.
		 */
		return NULL;
	}

	memcpy(&addr6, addr, addrlen);
	ifindex = (addr6.s6_addr[2] << 8) | addr6.s6_addr[3];
	addr6.s6_addr[2] = addr6.s6_addr[3] = 0;

	if (!IN6_IS_ADDR_LINKLOCAL(&addr6))
		return NULL;	/*XXX*/

	if ((hname = _icmp_fqdn_query(&addr6, ifindex)) == NULL)
		return NULL;
	return _hpaddr(af, hname, &addr6, errp);
}
#endif /* ICMPNL */