name6.c

用于嵌入式Linux系统的标准C的库函数

	hp->h_aliases = aliases;
	nalias = 0;
	for (i = 1; i <= 2; i++) {
		if ((pp = HP(i)->h_aliases) == NULL)
			continue;
		for (; nalias < MAXALIASES && *pp != NULL; pp++) {
			/* check duplicates */
			for (j = 0; j < nalias; j++)
				if (strcasecmp(*pp, aliases[j]) == 0)
					break;
			if (j == nalias)
				aliases[nalias++] = *pp;
		}
	}
	aliases[nalias] = NULL;
#ifdef INET6
	if (hp1->h_length != hp2->h_length) {
		hp->h_addrtype = AF_INET6;
		hp->h_length = sizeof(struct in6_addr);
	} else {
#endif
		hp->h_addrtype = hp1->h_addrtype;
		hp->h_length = hp1->h_length;
#ifdef INET6
	}
#endif
	hp->h_addr_list = addrs;
	naddr = 0;
	for (i = 1; i <= 2; i++) {
		if ((pp = HP(i)->h_addr_list) == NULL)
			continue;
		if (HP(i)->h_length == hp->h_length) {
			while (naddr < MAXADDRS && *pp != NULL)
				addrs[naddr++] = *pp++;
		} else {
			/* copy IPv4 addr as mapped IPv6 addr */
			while (naddr < MAXADDRS && *pp != NULL) {
				MAPADDR(&addrbuf[naddr], *pp++);
				addrs[naddr] = (char *)&addrbuf[naddr];
				naddr++;
			}
		}
	}
	addrs[naddr] = NULL;
	hp = _hpcopy(hp, errp);
	freehostent(hp1);
	freehostent(hp2);
	return hp;
}

/*
 * _hpmapv6: convert IPv4 hostent into IPv4-mapped IPv6 addresses
 */
#ifdef INET6
static struct hostent *
_hpmapv6(struct hostent *hp, int *errp)
{
	struct hostent *hp6;

	if (hp == NULL)
		return NULL;
	if (hp->h_addrtype == AF_INET6)
		return hp;

	/* make dummy hostent to convert IPv6 address */
	if ((hp6 = (struct hostent *)malloc(sizeof(struct hostent))) == NULL) {
		*errp = TRY_AGAIN;
		return NULL;
	}
	hp6->h_name = NULL;
	hp6->h_aliases = NULL;
	hp6->h_addrtype = AF_INET6;
	hp6->h_length = sizeof(struct in6_addr);
	hp6->h_addr_list = NULL;
	return _hpmerge(hp6, hp, errp);
}
#endif

/*
 * _hpsort: sort address by sortlist
 */
static struct hostent *
_hpsort(struct hostent *hp)
{
	int i, j, n;
	u_char *ap, *sp, *mp, **pp;
	char t;
	char order[MAXADDRS];
	int nsort = _res.nsort;

	if (hp == NULL || hp->h_addr_list[1] == NULL || nsort == 0)
		return hp;
	for (i = 0; (ap = (u_char *)hp->h_addr_list[i]); i++) {
		for (j = 0; j < nsort; j++) {
#ifdef INET6
			if (_res_ext.sort_list[j].af != hp->h_addrtype)
				continue;
			sp = (u_char *)&_res_ext.sort_list[j].addr;
			mp = (u_char *)&_res_ext.sort_list[j].mask;
#else
			sp = (u_char *)&_res.sort_list[j].addr;
			mp = (u_char *)&_res.sort_list[j].mask;
#endif
			for (n = 0; n < hp->h_length; n++) {
				if ((ap[n] & mp[n]) != sp[n])
					break;
			}
			if (n == hp->h_length)
				break;
		}
		order[i] = j;
	}
	n = i;
	pp = (u_char **)hp->h_addr_list;
	for (i = 0; i < n - 1; i++) {
		for (j = i + 1; j < n; j++) {
			if (order[i] > order[j]) {
				ap = pp[i];
				pp[i] = pp[j];
				pp[j] = ap;
				t = order[i];
				order[i] = order[j];
				order[j] = t;
			}
		}
	}
	return hp;
}

static char *
_hgetword(char **pp)
{
	char c, *p, *ret;
	const char *sp;
	static const char sep[] = "# \t\n";

	ret = NULL;
	for (p = *pp; (c = *p) != '\0'; p++) {
		for (sp = sep; *sp != '\0'; sp++) {
			if (c == *sp)
				break;
		}
		if (c == '#')
			p[1] = '\0';	/* ignore rest of line */
		if (ret == NULL) {
			if (*sp == '\0')
				ret = p;
		} else {
			if (*sp != '\0') {
				*p++ = '\0';
				break;
			}
		}
	}
	*pp = p;
	if (ret == NULL || *ret == '\0')
		return NULL;
	return ret;
}

/*
 * FILES (/etc/hosts)
 */

static FILE *
_files_open(int *errp)
{
	FILE *fp;
	fp = fopen(_PATH_HOSTS, "r");
	if (fp == NULL)
		*errp = NO_RECOVERY;
	return fp;
}

static int
_files_ghbyname(void *rval, void *cb_data, va_list ap)
{
	const char *name;
	int af; 
	int *errp;
	int match, nalias;
	char *p, *line, *addrstr, *cname;
	FILE *fp;
	struct hostent *rethp, *hp, hpbuf;
	char *aliases[MAXALIASES + 1], *addrs[2];
	union inx_addr addrbuf;
	char buf[BUFSIZ];
	int af0;

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

	*(struct hostent **)rval = NULL;

	if ((fp = _files_open(errp)) == NULL)
		return NS_UNAVAIL;
	rethp = hp = NULL;

	af0 = af;
	while (fgets(buf, sizeof(buf), fp)) {
		line = buf;
		if ((addrstr = _hgetword(&line)) == NULL
		||  (cname = _hgetword(&line)) == NULL)
			continue;
		match = (strcasecmp(cname, name) == 0);
		nalias = 0;
		while ((p = _hgetword(&line)) != NULL) {
			if (!match)
				match = (strcasecmp(p, name) == 0);
			if (nalias < MAXALIASES)
				aliases[nalias++] = p;
		}
		if (!match)
			continue;
		switch (af0) {
		case AF_INET:
			if (inet_aton(addrstr, (struct in_addr *)&addrbuf)
			    != 1) {
				*errp = NO_DATA;	/* name found */
				continue;
			}
			af = af0;
			break;
#ifdef INET6
		case AF_INET6:
			if (inet_pton(af, addrstr, &addrbuf) != 1) {
				*errp = NO_DATA;	/* name found */
				continue;
			}
			af = af0;
			break;
#endif
		case AF_UNSPEC:
			if (inet_aton(addrstr, (struct in_addr *)&addrbuf)
			    == 1) {
				af = AF_INET;
				break;
			}
#ifdef INET6
			if (inet_pton(AF_INET6, addrstr, &addrbuf) == 1) {
				af = AF_INET6;
				break; 
			}
#endif
			*errp = NO_DATA;	/* name found */
			continue;
			/* NOTREACHED */
		}
		hp = &hpbuf;
		hp->h_name = cname;
		hp->h_aliases = aliases;
		aliases[nalias] = NULL;
		hp->h_addrtype = af;
		hp->h_length = ADDRLEN(af);
		hp->h_addr_list = addrs;
		addrs[0] = (char *)&addrbuf;
		addrs[1] = NULL;
		hp = _hpcopy(hp, errp);
		rethp = _hpmerge(rethp, hp, errp);
	}
	fclose(fp);
	*(struct hostent **)rval = rethp;
	return (rethp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
}

static int
_files_ghbyaddr(void *rval, void *cb_data, va_list ap)
{
	const void *addr; 
	int addrlen; 
	int af; 
	int *errp;
	int nalias;
	char *p, *line;
	FILE *fp;
	struct hostent *hp, hpbuf;
	char *aliases[MAXALIASES + 1], *addrs[2];
	union inx_addr addrbuf;
	char buf[BUFSIZ];

	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;

	if ((fp = _files_open(errp)) == NULL)
		return NS_UNAVAIL;
	hp = NULL;
	while (fgets(buf, sizeof(buf), fp)) {
		line = buf;
		if ((p = _hgetword(&line)) == NULL
		||  (af == AF_INET
		     ? inet_aton(p, (struct in_addr *)&addrbuf)
		     : inet_pton(af, p, &addrbuf)) != 1
		||  memcmp(addr, &addrbuf, addrlen) != 0
		||  (p = _hgetword(&line)) == NULL)
			continue;
		hp = &hpbuf;
		hp->h_name = p;
		hp->h_aliases = aliases;
		nalias = 0;
		while ((p = _hgetword(&line)) != NULL) {
			if (nalias < MAXALIASES)
				aliases[nalias++] = p;
		}
		aliases[nalias] = NULL;
		hp->h_addrtype = af;
		hp->h_length = addrlen;
		hp->h_addr_list = addrs;
		addrs[0] = (char *)&addrbuf;
		addrs[1] = NULL;
		hp = _hpcopy(hp, errp);
		break;
	}
	fclose(fp);
	*(struct hostent **)rval = hp;
	return (hp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
}

#ifdef YP
/*
 * NIS
 *
 * XXX actually a hack, these are INET4 specific.
 */
static int
_nis_ghbyname(void *rval, void *cb_data, va_list ap)
{
	const char *name;
	int af;
	int *errp;
	struct hostent *hp = NULL;

	name = va_arg(ap, const char *);
	af = va_arg(ap, int);
	errp = va_arg(ap, int *);
	
	if (af == AF_UNSPEC)
		af = AF_INET;
	if (af == AF_INET) {
		hp = _gethostbynisname(name, af);
		if (hp != NULL)
			hp = _hpcopy(hp, errp);
	}
	
	*(struct hostent **)rval = hp;
	return (hp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
	
}

static int
_nis_ghbyaddr(void *rval, void *cb_data, va_list ap)
{
	const void *addr;
	int addrlen;
	int af;
	int *errp;
	struct hostent *hp = NULL;

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

	if (af == AF_INET) {
		hp = _gethostbynisaddr(addr, addrlen, af);
		if (hp != NULL)
			hp = _hpcopy(hp, errp);
	}
	*(struct hostent **)rval = hp;
	return (hp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
}
#endif
typedef struct __res_type_list res_type_list;

struct __res_type_list {
        res_type_list * rtl_entry;
        int     rtl_type;
};

#if PACKETSZ > 1024
#define	MAXPACKET	PACKETSZ
#else
#define	MAXPACKET	1024
#endif

typedef union {
	HEADER hdr;
	u_char buf[MAXPACKET];
} querybuf;

static struct hostent *getanswer(const querybuf *, int, const char *, int,
	    struct hostent *, int *);

/*
 * we don't need to take care about sorting, nor IPv4 mapped address here.
 */
static struct hostent *
getanswer(answer, anslen, qname, qtype, template, errp)
	const querybuf *answer;
	int anslen;
	const char *qname;
	int qtype;
	struct hostent *template;
	int *errp;
{
	const HEADER *hp;
	const u_char *cp;
	int n;
	const u_char *eom, *erdata;
	char *bp, **ap, **hap;
	int type, class, buflen, ancount, qdcount;
	int haveanswer, had_error;
	char tbuf[MAXDNAME];
	const char *tname;
	int (*name_ok)(const char *);
	static char *h_addr_ptrs[MAXADDRS + 1];
	static char *host_aliases[MAXALIASES];
	static char hostbuf[8*1024];

#define BOUNDED_INCR(x) \
	do { \
		cp += x; \
		if (cp > eom) { \
			*errp = NO_RECOVERY; \
			return (NULL); \
		} \
	} while (0)

#define BOUNDS_CHECK(ptr, count) \
	do { \
		if ((ptr) + (count) > eom) { \
			*errp = NO_RECOVERY; \
			return (NULL); \
		} \
	} while (0)

/* XXX do {} while (0) cannot be put here */
#define DNS_ASSERT(x) \
	{				\
		if (!(x)) {		\
			cp += n;	\
			continue;	\
		}			\
	}

/* XXX do {} while (0) cannot be put here */
#define DNS_FATAL(x) \
	{				\
		if (!(x)) {		\
			had_error++;	\
			continue;	\
		}			\
	}

	tname = qname;
	template->h_name = NULL;
	eom = answer->buf + anslen;
	switch (qtype) {
	case T_A:
	case T_AAAA:
		name_ok = res_hnok;
		break;
	case T_PTR:
		name_ok = res_dnok;
		break;
	default:
		return (NULL);	/* XXX should be abort(); */
	}
	/*
	 * find first satisfactory answer
	 */
	hp = &answer->hdr;
	ancount = ntohs(hp->ancount);
	qdcount = ntohs(hp->qdcount);
	bp = hostbuf;
	buflen = sizeof hostbuf;
	cp = answer->buf;
	BOUNDED_INCR(HFIXEDSZ);
	if (qdcount != 1) {
		*errp = NO_RECOVERY;
		return (NULL);
	}
	n = dn_expand(answer->buf, eom, cp, bp, buflen);
	if ((n < 0) || !(*name_ok)(bp)) {
		*errp = NO_RECOVERY;
		return (NULL);
	}
	BOUNDED_INCR(n + QFIXEDSZ);
	if (qtype == T_A || qtype == T_AAAA) {
		/* res_send() has already verified that the query name is the
		 * same as the one we sent; this just gets the expanded name
		 * (i.e., with the succeeding search-domain tacked on).
		 */
		n = strlen(bp) + 1;		/* for the \0 */
		if (n >= MAXHOSTNAMELEN) {
			*errp = NO_RECOVERY;
			return (NULL);
		}
		template->h_name = bp;
		bp += n;
		buflen -= n;
		/* The qname can be abbreviated, but h_name is now absolute. */
		qname = template->h_name;
	}
	ap = host_aliases;
	*ap = NULL;
	template->h_aliases = host_aliases;
	hap = h_addr_ptrs;
	*hap = NULL;
	template->h_addr_list = h_addr_ptrs;
	haveanswer = 0;
	had_error = 0;
	while (ancount-- > 0 && cp < eom && !had_error) {
		n = dn_expand(answer->buf, eom, cp, bp, buflen);
		DNS_FATAL(n >= 0);
		DNS_FATAL((*name_ok)(bp));
		cp += n;			/* name */
		BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
		type = _getshort(cp);
 		cp += INT16SZ;			/* type */
		class = _getshort(cp);
 		cp += INT16SZ + INT32SZ;	/* class, TTL */
		n = _getshort(cp);
		cp += INT16SZ;			/* len */
		BOUNDS_CHECK(cp, n);
		erdata = cp + n;
		DNS_ASSERT(class == C_IN);
		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
			if (ap >= &host_aliases[MAXALIASES-1])
				continue;
			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
			DNS_FATAL(n >= 0);
			DNS_FATAL((*name_ok)(tbuf));
			cp += n;
			if (cp != erdata) {
				*errp = NO_RECOVERY;
				return (NULL);
			}
			/* Store alias. */
			*ap++ = bp;
			n = strlen(bp) + 1;	/* for the \0 */
			DNS_FATAL(n < MAXHOSTNAMELEN);
			bp += n;
			buflen -= n;
			/* Get canonical name. */
			n = strlen(tbuf) + 1;	/* for the \0 */
			DNS_FATAL(n <= buflen);
			DNS_FATAL(n < MAXHOSTNAMELEN);
			strcpy(bp, tbuf);
			template->h_name = bp;
			bp += n;
			buflen -= n;
			continue;
		}
		if (qtype == T_PTR && type == T_CNAME) {
			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
			if (n < 0 || !res_dnok(tbuf)) {
				had_error++;
				continue;
			}
			cp += n;
			if (cp != erdata) {
				*errp = NO_RECOVERY;
				return (NULL);
			}
			/* Get canonical name. */
			n = strlen(tbuf) + 1;	/* for the \0 */
			if (n > buflen || n >= MAXHOSTNAMELEN) {
				had_error++;
				continue;
			}
			strcpy(bp, tbuf);
			tname = bp;
			bp += n;
			buflen -= n;
			continue;
		}
		DNS_ASSERT(type == qtype);
		switch (type) {
		case T_PTR:
			DNS_ASSERT(strcasecmp(tname, bp) == 0);
			n = dn_expand(answer->buf, eom, cp, bp, buflen);
			DNS_FATAL(n >= 0);
			DNS_FATAL(res_hnok(bp));
#if MULTI_PTRS_ARE_ALIASES
			cp += n;
			if (cp != erdata) {
				*errp = NO_RECOVERY;
				return (NULL);
			}
			if (!haveanswer)
				template->h_name = bp;
			else if (ap < &host_aliases[MAXALIASES-1])
				*ap++ = bp;
			else
				n = -1;
			if (n != -1) {
				n = strlen(bp) + 1;	/* for the \0 */
				if (n >= MAXHOSTNAMELEN) {
					had_error++;
					break;
				}