/*
**  MasqMail
**  Copyright (C) 1999 Oliver Kurth
**
**  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 2 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, write to the Free Software
**  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "masqmail.h"

static GList*
resolve_ip(gchar *ip)
{
	struct in_addr ia;
	mxip_addr mxip;

	if (!inet_aton(ip, &ia)) {
		/* No dots-and-numbers notation. */
		return NULL;
	}
	mxip.name = g_strdup(ip);
	mxip.pref = 0;
	mxip.ip = (guint32) * (guint32 *) (&ia);
	return g_list_append(NULL, g_memdup(&mxip, sizeof(mxip)));
}

mxip_addr*
connect_hostlist(int *psockfd, gchar *host, guint port, GList *addr_list)
{
	GList *addr_node;
	struct sockaddr_in saddr;
	int saved_errno;

	DEBUG(5) debugf("connect_hostlist entered\n");

	for (addr_node = g_list_first(addr_list); addr_node;
			addr_node = g_list_next(addr_node)) {
		mxip_addr *addr = (mxip_addr *) (addr_node->data);
		*psockfd = socket(PF_INET, SOCK_STREAM, 0);

		memset(&saddr, 0, sizeof(saddr));
		saddr.sin_family = AF_INET;
		saddr.sin_port = htons(port);
		/* clumsy, but makes compiler happy: */
		saddr.sin_addr = *(struct in_addr *) (&(addr->ip));

		DEBUG(5) debugf("  trying ip %s port %d\n",
				inet_ntoa(saddr.sin_addr), port);

		if (connect(*psockfd, (struct sockaddr *) &saddr,
				sizeof(saddr))==0) {
			DEBUG(5) debugf("  connected to %s\n",
					inet_ntoa(saddr.sin_addr));
			return addr;
		}

		saved_errno = errno;
		close(*psockfd);
		logwrite(LOG_WARNING, "connection to %s failed: %s\n",
				inet_ntoa(saddr.sin_addr), strerror(errno));
		errno = saved_errno;

		if ((saved_errno != ECONNREFUSED) &&
				(saved_errno != ETIMEDOUT) &&
				(saved_errno != ENETUNREACH) &&
				(saved_errno != EHOSTUNREACH)) {
			return NULL;
		}
	}
	return NULL;
}

/*
**  Given a list of resolver functions, this function
**  resolve the host and tries to connect to the addresses
**  returned. If a connection attemp is timed out or refused,
**  the next address is tried.
**
**  TODO: the resolver functions might return duplicate addresses,
**  if attempt failed for one it should not be tried again.
*/
mxip_addr*
connect_resolvelist(int *psockfd, gchar *host, guint port,
		GList *res_func_list)
{
	GList *res_node;
	GList *addr_list;

	DEBUG(5) debugf("connect_resolvelist entered\n");

	h_errno = 0;
	if (isdigit(*host)) {
		mxip_addr *addr;

		if ((addr_list = resolve_ip(host))) {
			addr = connect_hostlist(psockfd, host, port,
					addr_list);
			g_list_free(addr_list);
			return addr;
		}
		/*
		**  Probably a hostname that begins with a digit.
		**  E.g. '3dwars.de'. Thus fall ...
		*/
	}

	if (!res_func_list) {
		logwrite(LOG_ALERT, "res_funcs not set!\n");
		exit(1);
	}

	foreach(res_func_list, res_node) {
		resolve_func res_func;
		DEBUG(6) debugf("  foreach() body\n");

		res_func = (resolve_func) res_node->data;
		if (!res_func) {
			logwrite(LOG_ALERT, "Empty res_func!\n");
			exit(1);
		}

		errno = 0;
		if ((addr_list = res_func(NULL, host))) {

			mxip_addr *addr;
			if ((addr = connect_hostlist(psockfd, host, port,
					addr_list))) {
				return addr;
			}
			DEBUG(5) debugf("connect_hostlist failed: %s\n",
					strerror(errno));
			g_list_free(addr_list);
		} else if (!g_list_next(res_node)) {
			logwrite(LOG_ALERT, "could not resolve %s: %s\n",
					host, hstrerror(h_errno));
		}
	}
	return NULL;

}