getaddrinfo.c

Newlib 嵌入式 C库 标准实现代码

			pai->ai_family = ex->e_af;
		if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
			pai->ai_socktype = ex->e_socktype;
		if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
			pai->ai_protocol = ex->e_protocol;

		if (hostname == NULL)
			error = explore_null(pai, servname, &cur->ai_next);
		else
			error = explore_numeric_scope(pai, hostname, servname, &cur->ai_next);

		if (error)
			goto free;

		while (cur && cur->ai_next)
			cur = cur->ai_next;
	}

	/*
	 * XXX
	 * If numreic representation of AF1 can be interpreted as FQDN
	 * representation of AF2, we need to think again about the code below.
	 */
	if (sentinel.ai_next)
		goto good;

	if (pai->ai_flags & AI_NUMERICHOST)
		ERR(EAI_NONAME);
	if (hostname == NULL)
		ERR(EAI_NODATA);

	if ((pai->ai_flags & AI_ADDRCONFIG) != 0 && !addrconfig(&ai0))
		ERR(EAI_FAIL);

	/*
	 * hostname as alphabetical name.
	 * we would like to prefer AF_INET6 than AF_INET, so we'll make a
	 * outer loop by AFs.
	 */
	for (ex = explore; ex->e_af >= 0; ex++) {
		*pai = ai0;

		/* require exact match for family field */
		if (pai->ai_family != ex->e_af)
			continue;

		if (!MATCH(pai->ai_socktype, ex->e_socktype,
				WILD_SOCKTYPE(ex))) {
			continue;
		}
		if (!MATCH(pai->ai_protocol, ex->e_protocol,
				WILD_PROTOCOL(ex))) {
			continue;
		}

		if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
			pai->ai_socktype = ex->e_socktype;
		if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
			pai->ai_protocol = ex->e_protocol;

		error = explore_fqdn(pai, hostname, servname,
			&cur->ai_next);

		while (cur && cur->ai_next)
			cur = cur->ai_next;
	}

	/* XXX */
	if (sentinel.ai_next)
		error = 0;

	if (error)
		goto free;
	if (error == 0) {
		if (sentinel.ai_next) {
 good:
			*res = sentinel.ai_next;
			return SUCCESS;
		} else
			error = EAI_FAIL;
	}
 free:
 bad:
	if (sentinel.ai_next)
		freeaddrinfo(sentinel.ai_next);
	*res = NULL;
	return error;
}

/*
 * FQDN hostname, DNS lookup
 */
static int
explore_fqdn(pai, hostname, servname, res)
	const struct addrinfo *pai;
	const char *hostname;
	const char *servname;
	struct addrinfo **res;
{
	struct addrinfo *result;
	struct addrinfo *cur;
	int error = 0;
	static const ns_dtab dtab[] = {
		NS_FILES_CB(_files_getaddrinfo, NULL)
		{ NSSRC_DNS, _dns_getaddrinfo, NULL },	/* force -DHESIOD */
		NS_NIS_CB(_yp_getaddrinfo, NULL)
		{ 0 }
	};

	result = NULL;

	/*
	 * if the servname does not match socktype/protocol, ignore it.
	 */
	if (get_portmatch(pai, servname) != 0)
		return 0;

	switch (nsdispatch(&result, dtab, NSDB_HOSTS, "getaddrinfo",
			default_dns_files, hostname, pai)) {
	case NS_TRYAGAIN:
		error = EAI_AGAIN;
		goto free;
	case NS_UNAVAIL:
		error = EAI_FAIL;
		goto free;
	case NS_NOTFOUND:
		error = EAI_NODATA;
		goto free;
	case NS_SUCCESS:
		error = 0;
		for (cur = result; cur; cur = cur->ai_next) {
			GET_PORT(cur, servname);
			/* canonname should be filled already */
		}
		break;
	}

	*res = result;

	return 0;

free:
	if (result)
		freeaddrinfo(result);
	return error;
}

/*
 * hostname == NULL.
 * passive socket -> anyaddr (0.0.0.0 or ::)
 * non-passive socket -> localhost (127.0.0.1 or ::1)
 */
static int
explore_null(pai, servname, res)
	const struct addrinfo *pai;
	const char *servname;
	struct addrinfo **res;
{
	int s;
	const struct afd *afd;
	struct addrinfo *cur;
	struct addrinfo sentinel;
	int error;

	*res = NULL;
	sentinel.ai_next = NULL;
	cur = &sentinel;

	/*
	 * filter out AFs that are not supported by the kernel
	 * XXX errno?
	 */
	s = socket(pai->ai_family, SOCK_DGRAM, 0);
	if (s < 0) {
		if (errno != EMFILE)
			return 0;
	} else
		close(s);

	/*
	 * if the servname does not match socktype/protocol, ignore it.
	 */
	if (get_portmatch(pai, servname) != 0)
		return 0;

	afd = find_afd(pai->ai_family);
	if (afd == NULL)
		return 0;

	if (pai->ai_flags & AI_PASSIVE) {
		GET_AI(cur->ai_next, afd, afd->a_addrany);
		/* xxx meaningless?
		 * GET_CANONNAME(cur->ai_next, "anyaddr");
		 */
		GET_PORT(cur->ai_next, servname);
	} else {
		GET_AI(cur->ai_next, afd, afd->a_loopback);
		/* xxx meaningless?
		 * GET_CANONNAME(cur->ai_next, "localhost");
		 */
		GET_PORT(cur->ai_next, servname);
	}
	cur = cur->ai_next;

	*res = sentinel.ai_next;
	return 0;

free:
	if (sentinel.ai_next)
		freeaddrinfo(sentinel.ai_next);
	return error;
}

/*
 * numeric hostname
 */
static int
explore_numeric(pai, hostname, servname, res)
	const struct addrinfo *pai;
	const char *hostname;
	const char *servname;
	struct addrinfo **res;
{
	const struct afd *afd;
	struct addrinfo *cur;
	struct addrinfo sentinel;
	int error;
	char pton[PTON_MAX];

	*res = NULL;
	sentinel.ai_next = NULL;
	cur = &sentinel;

	/*
	 * if the servname does not match socktype/protocol, ignore it.
	 */
	if (get_portmatch(pai, servname) != 0)
		return 0;

	afd = find_afd(pai->ai_family);
	if (afd == NULL)
		return 0;

	switch (afd->a_af) {
#if 1 /*X/Open spec*/
	case AF_INET:
		if (inet_aton(hostname, (struct in_addr *)pton) == 1) {
			if (pai->ai_family == afd->a_af ||
			    pai->ai_family == PF_UNSPEC /*?*/) {
				GET_AI(cur->ai_next, afd, pton);
				GET_PORT(cur->ai_next, servname);
				while (cur && cur->ai_next)
					cur = cur->ai_next;
			} else
				ERR(EAI_FAMILY);	/*xxx*/
		}
		break;
#endif
	default:
		if (inet_pton(afd->a_af, hostname, pton) == 1) {
			if (pai->ai_family == afd->a_af ||
			    pai->ai_family == PF_UNSPEC /*?*/) {
				GET_AI(cur->ai_next, afd, pton);
				GET_PORT(cur->ai_next, servname);
				while (cur && cur->ai_next)
					cur = cur->ai_next;
			} else
				ERR(EAI_FAMILY);	/*xxx*/
		}
		break;
	}

	*res = sentinel.ai_next;
	return 0;

free:
bad:
	if (sentinel.ai_next)
		freeaddrinfo(sentinel.ai_next);
	return error;
}

/*
 * numeric hostname with scope
 */
static int
explore_numeric_scope(pai, hostname, servname, res)
	const struct addrinfo *pai;
	const char *hostname;
	const char *servname;
	struct addrinfo **res;
{
#if !defined(SCOPE_DELIMITER) || !defined(INET6)
	return explore_numeric(pai, hostname, servname, res);
#else
	const struct afd *afd;
	struct addrinfo *cur;
	int error;
	char *cp, *hostname2 = NULL, *scope, *addr;
	struct sockaddr_in6 *sin6;

	/*
	 * if the servname does not match socktype/protocol, ignore it.
	 */
	if (get_portmatch(pai, servname) != 0)
		return 0;

	afd = find_afd(pai->ai_family);
	if (afd == NULL)
		return 0;

	if (!afd->a_scoped)
		return explore_numeric(pai, hostname, servname, res);

	cp = strchr(hostname, SCOPE_DELIMITER);
	if (cp == NULL)
		return explore_numeric(pai, hostname, servname, res);

	/*
	 * Handle special case of <scoped_address><delimiter><scope id>
	 */
	hostname2 = strdup(hostname);
	if (hostname2 == NULL)
		return EAI_MEMORY;
	/* terminate at the delimiter */
	hostname2[cp - hostname] = '\0';
	addr = hostname2;
	scope = cp + 1;

	error = explore_numeric(pai, addr, servname, res);
	if (error == 0) {
		int scopeid;

		for (cur = *res; cur; cur = cur->ai_next) {
			if (cur->ai_family != AF_INET6)
				continue;
			sin6 = (struct sockaddr_in6 *)(void *)cur->ai_addr;
			if ((scopeid = ip6_str2scopeid(scope, sin6)) == -1) {
				free(hostname2);
				return(EAI_NODATA); /* XXX: is return OK? */
			}
			sin6->sin6_scope_id = scopeid;
		}
	}

	free(hostname2);

	return error;
#endif
}

static int
get_canonname(pai, ai, str)
	const struct addrinfo *pai;
	struct addrinfo *ai;
	const char *str;
{
	if ((pai->ai_flags & AI_CANONNAME) != 0) {
		ai->ai_canonname = (char *)malloc(strlen(str) + 1);
		if (ai->ai_canonname == NULL)
			return EAI_MEMORY;
		strcpy(ai->ai_canonname, str);
	}
	return 0;
}

static struct addrinfo *
get_ai(pai, afd, addr)
	const struct addrinfo *pai;
	const struct afd *afd;
	const char *addr;
{
	char *p;
	struct addrinfo *ai;
#ifdef FAITH
	struct in6_addr faith_prefix;
	char *fp_str;
	int translate = 0;
#endif

#ifdef FAITH
	/*
	 * Transfrom an IPv4 addr into a special IPv6 addr format for
	 * IPv6->IPv4 translation gateway. (only TCP is supported now)
	 *
	 * +-----------------------------------+------------+
	 * | faith prefix part (12 bytes)      | embedded   |
	 * |                                   | IPv4 addr part (4 bytes)
	 * +-----------------------------------+------------+
	 *
	 * faith prefix part is specified as ascii IPv6 addr format
	 * in environmental variable GAI.
	 * For FAITH to work correctly, routing to faith prefix must be
	 * setup toward a machine where a FAITH daemon operates.
	 * Also, the machine must enable some mechanizm
	 * (e.g. faith interface hack) to divert those packet with
	 * faith prefixed destination addr to user-land FAITH daemon.
	 */
	fp_str = getenv("GAI");
	if (fp_str && inet_pton(AF_INET6, fp_str, &faith_prefix) == 1 &&
	    afd->a_af == AF_INET && pai->ai_socktype == SOCK_STREAM) {
		u_int32_t v4a;
		u_int8_t v4a_top;

		memcpy(&v4a, addr, sizeof v4a);
		v4a_top = v4a >> IN_CLASSA_NSHIFT;
		if (!IN_MULTICAST(v4a) && !IN_EXPERIMENTAL(v4a) &&
		    v4a_top != 0 && v4a != IN_LOOPBACKNET) {
			afd = &afdl[N_INET6];
			memcpy(&faith_prefix.s6_addr[12], addr,
			       sizeof(struct in_addr));
			translate = 1;
		}
	}
#endif

	ai = (struct addrinfo *)malloc(sizeof(struct addrinfo)
		+ (afd->a_socklen));
	if (ai == NULL)
		return NULL;

	memcpy(ai, pai, sizeof(struct addrinfo));
	ai->ai_addr = (struct sockaddr *)(void *)(ai + 1);
	memset(ai->ai_addr, 0, (size_t)afd->a_socklen);
	ai->ai_addrlen = afd->a_socklen;
	ai->ai_addr->sa_family = ai->ai_family = afd->a_af;
	p = (char *)(void *)(ai->ai_addr);
#ifdef FAITH
	if (translate == 1)
		memcpy(p + afd->a_off, &faith_prefix, (size_t)afd->a_addrlen);
	else
#endif
	memcpy(p + afd->a_off, addr, (size_t)afd->a_addrlen);
	return ai;
}

static int
get_portmatch(ai, servname)
	const struct addrinfo *ai;
	const char *servname;
{

	/* get_port does not touch first argument. when matchonly == 1. */
	/* LINTED const cast */
	return get_port((struct addrinfo *)ai, servname, 1);
}

static int
get_port(ai, servname, matchonly)
	struct addrinfo *ai;
	const char *servname;
	int matchonly;
{
	const char *proto;
	struct servent *sp;
	int port;
	int allownumeric;

	if (servname == NULL)
		return 0;
	switch (ai->ai_family) {
	case AF_INET:
#ifdef AF_INET6
	case AF_INET6:
#endif
		break;
	default:
		return 0;
	}

	switch (ai->ai_socktype) {
	case SOCK_RAW:
		return EAI_SERVICE;
	case SOCK_DGRAM:
	case SOCK_STREAM:
		allownumeric = 1;
		break;
	case ANY:
		allownumeric = 0;
		break;
	default:
		return EAI_SOCKTYPE;
	}

	if (str_isnumber(servname)) {
		if (!allownumeric)
			return EAI_SERVICE;
		port = htons(atoi(servname));
		if (port < 0 || port > 65535)
			return EAI_SERVICE;
	} else {
		switch (ai->ai_socktype) {
		case SOCK_DGRAM:
			proto = "udp";
			break;