/*

 * resolving DNS hostname routine

 *

 * Copyright (C) 2010 Jeff Layton (jlayton@samba.org)

 * Copyright (C) 2010 Igor Druzhinin (jaxbrigs@gmail.com)

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif /* HAVE_CONFIG_H */

#include <stdio.h>

#include <string.h>

#include <sys/socket.h>

#include <arpa/inet.h>

#include <netdb.h>

#include "mount.h"

#include "util.h"

#include "resolve_host.h"

/*

 * resolve hostname to comma-separated list of address(es)

 */

int resolve_host(const char *host, char *addrstr)

{

	int rc;

	/* 10 for max width of decimal scopeid */

	char tmpbuf[NI_MAXHOST + 1 + 10 + 1];

	const char *ipaddr;

	size_t len;

	struct addrinfo *addrlist, *addr;

	struct sockaddr_in *sin;

	struct sockaddr_in6 *sin6;

	rc = getaddrinfo(host, NULL, NULL, &addrlist);

	if (rc != 0)

		return EX_USAGE;

	addr = addrlist;

	while (addr) {

		/* skip non-TCP entries */

		if (addr->ai_socktype != SOCK_STREAM ||

		    addr->ai_protocol != IPPROTO_TCP) {

			addr = addr->ai_next;

			continue;

		}

		switch (addr->ai_addr->sa_family) {

		case AF_INET6:

			sin6 = (struct sockaddr_in6 *)addr->ai_addr;

			ipaddr = inet_ntop(AF_INET6, &sin6->sin6_addr, tmpbuf,

					   sizeof(tmpbuf));

			if (!ipaddr) {

				rc = EX_SYSERR;

				goto resolve_host_out;

			}

			if (sin6->sin6_scope_id) {

				len = strnlen(tmpbuf, sizeof(tmpbuf));

				snprintf(tmpbuf + len, sizeof(tmpbuf) - len, "%%%u",

					 sin6->sin6_scope_id);

			}

			break;

		case AF_INET:

			sin = (struct sockaddr_in *)addr->ai_addr;

			ipaddr = inet_ntop(AF_INET, &sin->sin_addr, tmpbuf,

					   sizeof(tmpbuf));

			if (!ipaddr) {

				rc = EX_SYSERR;

				goto resolve_host_out;

			}

			break;

		default:

			addr = addr->ai_next;

			continue;

		}

		if (addr == addrlist)

			*addrstr = '\0';

		else

			strlcat(addrstr, ",", MAX_ADDR_LIST_LEN);

		strlcat(addrstr, tmpbuf, MAX_ADDR_LIST_LEN);

		addr = addr->ai_next;

	}

resolve_host_out:

	freeaddrinfo(addrlist);

	return rc;

}