getaddrinfo.c

Newlib 嵌入式 C库 标准实现代码

		if (pai->ai_flags & AI_CANONNAME) {
			if (get_canonname(pai, res, cname) != 0) {
				freeaddrinfo(res0);
				goto again;
			}
		}
	}
	return res0;
}

/*ARGSUSED*/
static int
_files_getaddrinfo(rv, cb_data, ap)
	void	*rv;
	void	*cb_data;
	va_list	 ap;
{
	const char *name;
	const struct addrinfo *pai;
	struct addrinfo sentinel, *cur;
	struct addrinfo *p;

	name = va_arg(ap, char *);
	pai = va_arg(ap, struct addrinfo *);

	memset(&sentinel, 0, sizeof(sentinel));
	cur = &sentinel;

	_sethtent();
	while ((p = _gethtent(name, pai)) != NULL) {
		cur->ai_next = p;
		while (cur && cur->ai_next)
			cur = cur->ai_next;
	}
	_endhtent();

	*((struct addrinfo **)rv) = sentinel.ai_next;
	if (sentinel.ai_next == NULL)
		return NS_NOTFOUND;
	return NS_SUCCESS;
}

#ifdef YP
static char *__ypdomain;

/*ARGSUSED*/
static struct addrinfo *
_yphostent(line, pai)
	char *line;
	const struct addrinfo *pai;
{
	struct addrinfo sentinel, *cur;
	struct addrinfo hints, *res, *res0;
	int error;
	char *p = line;
	const char *addr, *canonname;
	char *nextline;
	char *cp;

	addr = canonname = NULL;

	memset(&sentinel, 0, sizeof(sentinel));
	cur = &sentinel;

nextline:
	/* terminate line */
	cp = strchr(p, '\n');
	if (cp) {
		*cp++ = '\0';
		nextline = cp;
	} else
		nextline = NULL;

	cp = strpbrk(p, " \t");
	if (cp == NULL) {
		if (canonname == NULL)
			return (NULL);
		else
			goto done;
	}
	*cp++ = '\0';

	addr = p;

	while (cp && *cp) {
		if (*cp == ' ' || *cp == '\t') {
			cp++;
			continue;
		}
		if (!canonname)
			canonname = cp;
		if ((cp = strpbrk(cp, " \t")) != NULL)
			*cp++ = '\0';
	}

	hints = *pai;
	hints.ai_flags = AI_NUMERICHOST;
	error = getaddrinfo(addr, NULL, &hints, &res0);
	if (error == 0) {
		for (res = res0; res; res = res->ai_next) {
			/* cover it up */
			res->ai_flags = pai->ai_flags;

			if (pai->ai_flags & AI_CANONNAME)
				(void)get_canonname(pai, res, canonname);
		}
	} else
		res0 = NULL;
	if (res0) {
		cur->ai_next = res0;
		while (cur && cur->ai_next)
			cur = cur->ai_next;
	}

	if (nextline) {
		p = nextline;
		goto nextline;
	}

done:
	return sentinel.ai_next;
}

/*ARGSUSED*/
static int
_yp_getaddrinfo(rv, cb_data, ap)
	void	*rv;
	void	*cb_data;
	va_list	 ap;
{
	struct addrinfo sentinel, *cur;
	struct addrinfo *ai = NULL;
	static char *__ypcurrent;
	int __ypcurrentlen, r;
	const char *name;
	const struct addrinfo *pai;

	name = va_arg(ap, char *);
	pai = va_arg(ap, const struct addrinfo *);

	memset(&sentinel, 0, sizeof(sentinel));
	cur = &sentinel;

	if (!__ypdomain) {
		if (_yp_check(&__ypdomain) == 0)
			return NS_UNAVAIL;
	}
	if (__ypcurrent)
		free(__ypcurrent);
	__ypcurrent = NULL;

	/* hosts.byname is only for IPv4 (Solaris8) */
	if (pai->ai_family == PF_UNSPEC || pai->ai_family == PF_INET) {
		r = yp_match(__ypdomain, "hosts.byname", name,
			(int)strlen(name), &__ypcurrent, &__ypcurrentlen);
		if (r == 0) {
			struct addrinfo ai4;

			ai4 = *pai;
			ai4.ai_family = AF_INET;
			ai = _yphostent(__ypcurrent, &ai4);
			if (ai) {
				cur->ai_next = ai;
				while (cur && cur->ai_next)
					cur = cur->ai_next;
			}
		}
	}

	/* ipnodes.byname can hold both IPv4/v6 */
	r = yp_match(__ypdomain, "ipnodes.byname", name,
		(int)strlen(name), &__ypcurrent, &__ypcurrentlen);
	if (r == 0) {
		ai = _yphostent(__ypcurrent, pai);
		if (ai) {
			cur->ai_next = ai;
			while (cur && cur->ai_next)
				cur = cur->ai_next;
		}
	}

	if (sentinel.ai_next == NULL) {
		h_errno = HOST_NOT_FOUND;
		return NS_NOTFOUND;
	}
	*((struct addrinfo **)rv) = sentinel.ai_next;
	return NS_SUCCESS;
}
#endif

/* resolver logic */

extern const char *__hostalias(const char *);
extern int h_errno;

/*
 * Formulate a normal query, send, and await answer.
 * Returned answer is placed in supplied buffer "answer".
 * Perform preliminary check of answer, returning success only
 * if no error is indicated and the answer count is nonzero.
 * Return the size of the response on success, -1 on error.
 * Error number is left in h_errno.
 *
 * Caller must parse answer and determine whether it answers the question.
 */
static int
res_queryN(name, target)
	const char *name;	/* domain name */
	struct res_target *target;
{
	u_char buf[MAXPACKET];
	HEADER *hp;
	int n;
	struct res_target *t;
	int rcode;
	int ancount;

	rcode = NOERROR;
	ancount = 0;

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (-1);
	}

	for (t = target; t; t = t->next) {
		int class, type;
		u_char *answer;
		int anslen;

		hp = (HEADER *)(void *)t->answer;
		hp->rcode = NOERROR;	/* default */

		/* make it easier... */
		class = t->qclass;
		type = t->qtype;
		answer = t->answer;
		anslen = t->anslen;
#ifdef DEBUG
		if (_res.options & RES_DEBUG)
			printf(";; res_query(%s, %d, %d)\n", name, class, type);
#endif

		n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL,
		    buf, sizeof(buf));
		if (n > 0 && (_res.options & RES_USE_EDNS0) != 0)
			n = res_opt(n, buf, sizeof(buf), anslen);
		if (n <= 0) {
#ifdef DEBUG
			if (_res.options & RES_DEBUG)
				printf(";; res_query: mkquery failed\n");
#endif
			h_errno = NO_RECOVERY;
			return (n);
		}
		n = res_send(buf, n, answer, anslen);
#if 0
		if (n < 0) {
#ifdef DEBUG
			if (_res.options & RES_DEBUG)
				printf(";; res_query: send error\n");
#endif
			h_errno = TRY_AGAIN;
			return (n);
		}
#endif

		if (n < 0 || hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
			rcode = hp->rcode;	/* record most recent error */
#ifdef DEBUG
			if (_res.options & RES_DEBUG)
				printf(";; rcode = %d, ancount=%d\n", hp->rcode,
				    ntohs(hp->ancount));
#endif
			continue;
		}

		ancount += ntohs(hp->ancount);

		t->n = n;
	}

	if (ancount == 0) {
		switch (rcode) {
		case NXDOMAIN:
			h_errno = HOST_NOT_FOUND;
			break;
		case SERVFAIL:
			h_errno = TRY_AGAIN;
			break;
		case NOERROR:
			h_errno = NO_DATA;
			break;
		case FORMERR:
		case NOTIMP:
		case REFUSED:
		default:
			h_errno = NO_RECOVERY;
			break;
		}
		return (-1);
	}
	return (ancount);
}

/*
 * Formulate a normal query, send, and retrieve answer in supplied buffer.
 * Return the size of the response on success, -1 on error.
 * If enabled, implement search rules until answer or unrecoverable failure
 * is detected.  Error code, if any, is left in h_errno.
 */
static int
res_searchN(name, target)
	const char *name;	/* domain name */
	struct res_target *target;
{
	const char *cp, * const *domain;
	HEADER *hp = (HEADER *)(void *)target->answer;	/*XXX*/
	u_int dots;
	int trailing_dot, ret, saved_herrno;
	int got_nodata = 0, got_servfail = 0, tried_as_is = 0;

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (-1);
	}

	errno = 0;
	h_errno = HOST_NOT_FOUND;	/* default, if we never query */
	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)
		return (res_queryN(cp, target));

	/*
	 * 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) {
		ret = res_querydomainN(name, NULL, target);
		if (ret > 0)
			return (ret);
		saved_herrno = h_errno;
		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++) {

			ret = res_querydomainN(name, *domain, target);
			if (ret > 0)
				return (ret);

			/*
			 * 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) {
				h_errno = TRY_AGAIN;
				return (-1);
			}

			switch (h_errno) {
			case NO_DATA:
				got_nodata++;
				/* FALLTHROUGH */
			case HOST_NOT_FOUND:
				/* keep trying */
				break;
			case TRY_AGAIN:
				if (hp->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.
	 */
	if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) {
		ret = res_querydomainN(name, NULL, target);
		if (ret > 0)
			return (ret);
	}

	/*
	 * 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)
		h_errno = saved_herrno;
	else if (got_nodata)
		h_errno = NO_DATA;
	else if (got_servfail)
		h_errno = TRY_AGAIN;
	return (-1);
}

/*
 * Perform a call on res_query on the concatenation of name and domain,
 * removing a trailing dot from name if domain is NULL.
 */
static int
res_querydomainN(name, domain, target)
	const char *name, *domain;
	struct res_target *target;
{
	char nbuf[MAXDNAME];
	const char *longname = nbuf;
	size_t n, d;

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (-1);
	}
#ifdef DEBUG
	if (_res.options & RES_DEBUG)
		printf(";; res_querydomain(%s, %s)\n",
			name, domain?domain:"<Nil>");
#endif
	if (domain == NULL) {
		/*
		 * Check for trailing '.';
		 * copy without '.' if present.
		 */
		n = strlen(name);
		if (n >= MAXDNAME) {
			h_errno = NO_RECOVERY;
			return (-1);
		}
		if (n > 0 && name[--n] == '.') {
			strncpy(nbuf, name, n);
			nbuf[n] = '\0';
		} else
			longname = name;
	} else {
		n = strlen(name);
		d = strlen(domain);
		if (n + d + 1 >= MAXDNAME) {
			h_errno = NO_RECOVERY;
			return (-1);
		}
		sprintf(nbuf, "%s.%s", name, domain);
	}
	return (res_queryN(longname, target));
}