/*-
 * Copyright 2016 Vsevolod Stakhov
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


#include <contrib/librdns/rdns.h>
#include "config.h"
#include "dns.h"
#include "rspamd.h"
#include "utlist.h"
#include "contrib/librdns/rdns.h"
#include "contrib/librdns/dns_private.h"
#include "contrib/librdns/rdns_ev.h"
#include "unix-std.h"

static const gchar *M = "rspamd dns";

static struct rdns_upstream_elt* rspamd_dns_select_upstream (const char *name,
		size_t len, void *ups_data);
static struct rdns_upstream_elt* rspamd_dns_select_upstream_retransmit (
		const char *name,
		size_t len,
		struct rdns_upstream_elt *prev_elt,
		void *ups_data);
static void rspamd_dns_upstream_ok (struct rdns_upstream_elt *elt,
		void *ups_data);
static void rspamd_dns_upstream_fail (struct rdns_upstream_elt *elt,
		void *ups_data, const gchar *reason);
static unsigned int rspamd_dns_upstream_count (void *ups_data);

static struct rdns_upstream_context rspamd_ups_ctx = {
		.select = rspamd_dns_select_upstream,
		.select_retransmit = rspamd_dns_select_upstream_retransmit,
		.ok = rspamd_dns_upstream_ok,
		.fail = rspamd_dns_upstream_fail,
		.count = rspamd_dns_upstream_count,
		.data = NULL
};

struct rspamd_dns_request_ud {
	struct rspamd_async_session *session;
	dns_callback_type cb;
	gpointer ud;
	rspamd_mempool_t *pool;
	struct rspamd_task *task;
	struct rspamd_symcache_item *item;
	struct rdns_request *req;
	struct rdns_reply *reply;
};

struct rspamd_dns_fail_cache_entry {
	const char *name;
	gint32 namelen;
	enum rdns_request_type type;
};

static guint
rspamd_dns_fail_hash (gconstpointer ptr)
{
	struct rspamd_dns_fail_cache_entry *elt =
			(struct rspamd_dns_fail_cache_entry *)ptr;

	/* We don't care about type when doing hashing */
	return rspamd_cryptobox_fast_hash (elt->name, elt->namelen,
			rspamd_hash_seed ());
}

static gboolean
rspamd_dns_fail_equal (gconstpointer p1, gconstpointer p2)
{
	struct rspamd_dns_fail_cache_entry *e1 = (struct rspamd_dns_fail_cache_entry *)p1,
			*e2 = (struct rspamd_dns_fail_cache_entry *)p2;

	if (e1->type == e2->type && e1->namelen == e2->namelen) {
		return memcmp (e1->name, e2->name, e1->namelen) == 0;
	}

	return FALSE;
}

static void
rspamd_dns_fin_cb (gpointer arg)
{
	struct rspamd_dns_request_ud *reqdata = (struct rspamd_dns_request_ud *)arg;

	if (reqdata->item) {
		rspamd_symcache_set_cur_item (reqdata->task, reqdata->item);
	}

	if (reqdata->reply) {
		reqdata->cb (reqdata->reply, reqdata->ud);
	}
	else {
		struct rdns_reply fake_reply;

		memset (&fake_reply, 0, sizeof (fake_reply));
		fake_reply.code = RDNS_RC_TIMEOUT;
		fake_reply.request = reqdata->req;
		fake_reply.resolver = reqdata->req->resolver;
		fake_reply.requested_name = reqdata->req->requested_names[0].name;

		reqdata->cb (&fake_reply, reqdata->ud);
	}

	rdns_request_release (reqdata->req);

	if (reqdata->item) {
		rspamd_symcache_item_async_dec_check (reqdata->task,
				reqdata->item, M);
	}

	if (reqdata->pool == NULL) {
		g_free (reqdata);
	}
}

static void
rspamd_dns_callback (struct rdns_reply *reply, gpointer ud)
{
	struct rspamd_dns_request_ud *reqdata = ud;

	reqdata->reply = reply;


	if (reqdata->session) {
		if (reply->code == RDNS_RC_SERVFAIL &&
			reqdata->task &&
			reqdata->task->resolver->fails_cache) {

			/* Add to cache... */
			const gchar *name = reqdata->req->requested_names[0].name;
			gchar *target;
			gsize namelen;
			struct rspamd_dns_fail_cache_entry *nentry;

			/* Allocate in a single entry to allow further free in a single call */
			namelen = strlen (name);
			nentry = g_malloc (sizeof (nentry) + namelen + 1);
			target = ((gchar *)nentry) + sizeof (nentry);
			rspamd_strlcpy (target, name, namelen + 1);
			nentry->type = reqdata->req->requested_names[0].type;
			nentry->name = target;
			nentry->namelen = namelen;

			/* Rdns request is retained there */
			rspamd_lru_hash_insert (reqdata->task->resolver->fails_cache,
					nentry, rdns_request_retain (reply->request),
					reqdata->task->task_timestamp,
					reqdata->task->resolver->fails_cache_time);
		}

		/*
		 * Ref event to avoid double unref by
		 * event removing
		 */
		rdns_request_retain (reply->request);
		rspamd_session_remove_event (reqdata->session,
				rspamd_dns_fin_cb, reqdata);
	}
	else {
		reqdata->cb (reply, reqdata->ud);

		if (reqdata->pool == NULL) {
			g_free (reqdata);
		}
	}
}

struct rspamd_dns_request_ud *
rspamd_dns_resolver_request (struct rspamd_dns_resolver *resolver,
							 struct rspamd_async_session *session,
							 rspamd_mempool_t *pool,
							 dns_callback_type cb,
							 gpointer ud,
							 enum rdns_request_type type,
							 const char *name)
{
	struct rdns_request *req;
	struct rspamd_dns_request_ud *reqdata = NULL;

	g_assert (resolver != NULL);

	if (resolver->r == NULL) {
		return NULL;
	}

	if (session && rspamd_session_blocked (session)) {
		return NULL;
	}

	if (pool != NULL) {
		reqdata =
			rspamd_mempool_alloc0 (pool, sizeof (struct rspamd_dns_request_ud));
	}
	else {
		reqdata = g_malloc0 (sizeof (struct rspamd_dns_request_ud));
	}

	reqdata->pool = pool;
	reqdata->session = session;
	reqdata->cb = cb;
	reqdata->ud = ud;

	req = rdns_make_request_full (resolver->r, rspamd_dns_callback, reqdata,
			resolver->request_timeout, resolver->max_retransmits, 1, name,
			type);
	reqdata->req = req;

	if (session) {
		if (req != NULL) {
			rspamd_session_add_event (session,
					(event_finalizer_t) rspamd_dns_fin_cb,
					reqdata,
					M);
		}
	}

	if (req == NULL) {
		if (pool == NULL) {
			g_free (reqdata);
		}

		return NULL;
	}

	return reqdata;
}

struct rspamd_dns_cached_delayed_cbdata {
	struct rspamd_task *task;
	dns_callback_type cb;
	gpointer ud;
	ev_timer tm;
	struct rdns_request *req;
};

static void
rspamd_fail_cache_cb (EV_P_ ev_timer *w, int revents)
{
	struct rspamd_dns_cached_delayed_cbdata *cbd =
			(struct rspamd_dns_cached_delayed_cbdata *)w->data;
	struct rdns_reply fake_reply;

	ev_timer_stop (EV_A_ w);
	memset (&fake_reply, 0, sizeof (fake_reply));
	fake_reply.code = RDNS_RC_SERVFAIL;
	fake_reply.request = cbd->req;
	fake_reply.resolver = cbd->req->resolver;
	fake_reply.requested_name = cbd->req->requested_names[0].name;
	cbd->cb (&fake_reply, cbd->ud);
	rdns_request_release (cbd->req);
}

static gboolean
make_dns_request_task_common (struct rspamd_task *task,
							  dns_callback_type cb,
							  gpointer ud,
							  enum rdns_request_type type,
							  const char *name,
							  gboolean forced)
{
	struct rspamd_dns_request_ud *reqdata;

	if (!forced && task->dns_requests >= task->cfg->dns_max_requests) {
		return FALSE;
	}

	if (task->resolver->fails_cache) {
		/* Search in failures cache */
		struct rspamd_dns_fail_cache_entry search;
		struct rdns_request *req;

		search.name = name;
		search.namelen = strlen (name);
		search.type = type;

		if ((req = rspamd_lru_hash_lookup (task->resolver->fails_cache,
				&search, task->task_timestamp)) != NULL) {
			/*
			 * We need to reply with SERVFAIL again to the API, so add a special
			 * timer, uh-oh, and fire it
			 */
			struct rspamd_dns_cached_delayed_cbdata *cbd =
					rspamd_mempool_alloc0 (task->task_pool, sizeof (*cbd));

			ev_timer_init (&cbd->tm, rspamd_fail_cache_cb, 0.0, 0.0);
			cbd->task = task;
			cbd->cb = cb;
			cbd->ud = ud;
			cbd->req = rdns_request_retain (req);
			cbd->tm.data = cbd;

			return TRUE;
		}
	}

	reqdata = rspamd_dns_resolver_request (
			task->resolver, task->s, task->task_pool, cb, ud,
			type, name);

	if (reqdata) {
		task->dns_requests ++;

		reqdata->task = task;
		reqdata->item = rspamd_symcache_get_cur_item (task);

		if (reqdata->item) {
			/* We are inside some session */
			rspamd_symcache_item_async_inc (task, reqdata->item, M);
		}

		if (!forced && task->dns_requests >= task->cfg->dns_max_requests) {
			msg_info_task ("stop resolving on reaching %ud requests",
					task->dns_requests);
		}

		return TRUE;
	}

	return FALSE;
}

gboolean
rspamd_dns_resolver_request_task (struct rspamd_task *task,
								  dns_callback_type cb,
								  gpointer ud,
								  enum rdns_request_type type,
								  const char *name)
{
	return make_dns_request_task_common (task, cb, ud, type, name, FALSE);
}

gboolean
rspamd_dns_resolver_request_task_forced (struct rspamd_task *task,
										 dns_callback_type cb,
										 gpointer ud,
										 enum rdns_request_type type,
										 const char *name)
{
	return make_dns_request_task_common (task, cb, ud, type, name, TRUE);
}

static void rspamd_rnds_log_bridge (
		void *log_data,
		enum rdns_log_level level,
		const char *function,
		const char *format,
		va_list args)
{
	rspamd_logger_t *logger = log_data;

	rspamd_common_logv (logger, (GLogLevelFlags)level, "rdns", NULL,
			function, format, args);
}

static void
rspamd_dns_server_init (struct upstream *up, guint idx, gpointer ud)
{
	struct rspamd_dns_resolver *r = ud;
	rspamd_inet_addr_t *addr;
	void *serv;
	struct rdns_upstream_elt *elt;

	addr = rspamd_upstream_addr_next (up);

	if (r->cfg) {
		serv = rdns_resolver_add_server (r->r, rspamd_inet_address_to_string (addr),
				rspamd_inet_address_get_port (addr), 0, r->cfg->dns_io_per_server);
	}
	else {
		serv = rdns_resolver_add_server (r->r, rspamd_inet_address_to_string (addr),
				rspamd_inet_address_get_port (addr), 0, 8);
	}

	g_assert (serv != NULL);

	elt = rspamd_mempool_alloc0 (r->cfg->cfg_pool, sizeof (*elt));
	elt->server = serv;
	elt->lib_data = up;

	rspamd_upstream_set_data (up, elt);
}

static void
rspamd_dns_server_reorder (struct upstream *up, guint idx, gpointer ud)
{
	struct rspamd_dns_resolver *r = ud;

	rspamd_upstream_set_weight (up, rspamd_upstreams_count (r->ups) - idx + 1);
}

static bool
rspamd_dns_resolv_conf_on_server (struct rdns_resolver *resolver,
		const char *name, unsigned int port,
		int priority, unsigned int io_cnt, void *ud)
{
	struct rspamd_dns_resolver *dns_resolver = ud;
	struct rspamd_config *cfg;
	rspamd_inet_addr_t *addr;
	gint test_fd;

	cfg = dns_resolver->cfg;

	msg_info_config ("parsed nameserver %s from resolv.conf", name);

	/* Try to open a connection */
	if (!rspamd_parse_inet_address (&addr, name, strlen (name),
			RSPAMD_INET_ADDRESS_PARSE_DEFAULT)) {
		msg_warn_config ("cannot parse nameserver address %s", name);

		return FALSE;
	}

	rspamd_inet_address_set_port (addr, port);
	test_fd = rspamd_inet_address_connect (addr, SOCK_DGRAM, TRUE);

	if (test_fd == -1 && (errno != EINTR || errno != ECONNREFUSED || errno != ECONNRESET)) {
		msg_info_config ("cannot open connection to nameserver at address %s: %s",
				name, strerror (errno));
		rspamd_inet_address_free (addr);

		return FALSE;
	}

	rspamd_inet_address_free (addr);
	close (test_fd);

	return rspamd_upstreams_add_upstream (dns_resolver->ups, name, port,
			RSPAMD_UPSTREAM_PARSE_NAMESERVER,
			NULL);
}

static void
rspamd_process_fake_reply (struct rspamd_config *cfg,
		struct rspamd_dns_resolver *dns_resolver,
		const ucl_object_t *cur_arr)
{
	const ucl_object_t *cur;
	ucl_object_iter_t it;

	it = ucl_object_iterate_new (cur_arr);

	while ((cur = ucl_object_iterate_safe (it, true))) {
		const ucl_object_t *type_obj, *name_obj, *code_obj, *replies_obj;
		enum rdns_request_type rtype = RDNS_REQUEST_A;
		enum dns_rcode rcode = RDNS_RC_NOERROR;
		struct rdns_reply_entry *replies = NULL;
		const gchar *name = NULL;

		if (ucl_object_type (cur) != UCL_OBJECT) {
			continue;
		}

		name_obj = ucl_object_lookup (cur, "name");
		if (name_obj == NULL ||
			(name = ucl_object_tostring (name_obj)) == NULL) {
			msg_err_config ("no name for fake dns reply");
			continue;
		}

		type_obj = ucl_object_lookup (cur, "type");
		if (type_obj) {
			rtype = rdns_type_fromstr (ucl_object_tostring (type_obj));

			if (rtype == RDNS_REQUEST_INVALID) {
				msg_err_config ("invalid type for %s: %s", name,
						ucl_object_tostring (type_obj));
				continue;
			}
		}

		code_obj = ucl_object_lookup_any (cur, "code", "rcode", NULL);
		if (code_obj) {
			rcode = rdns_rcode_fromstr (ucl_object_tostring (code_obj));

			if (rcode == RDNS_RC_INVALID) {
				msg_err_config ("invalid rcode for %s: %s", name,
						ucl_object_tostring (code_obj));
				continue;
			}
		}

		if (rcode == RDNS_RC_NOERROR) {
			/* We want replies to be set for this rcode */
			replies_obj = ucl_object_lookup (cur, "replies");

			if (replies_obj == NULL || ucl_object_type (replies_obj) != UCL_ARRAY) {
				msg_err_config ("invalid replies for fake DNS record %s", name);
				continue;
			}

			ucl_object_iter_t rep_it;
			const ucl_object_t *rep_obj;

			rep_it = ucl_object_iterate_new (replies_obj);

			while ((rep_obj = ucl_object_iterate_safe (rep_it, true))) {
				const gchar *str_rep = ucl_object_tostring (rep_obj);
				struct rdns_reply_entry *rep;
				gchar **svec;

				if (str_rep == NULL) {
					msg_err_config ("invalid reply element for fake DNS record %s",
							name);
					continue;
				}

				rep = calloc (1, sizeof (*rep));
				g_assert (rep != NULL);

				rep->type = rtype;
				rep->ttl = 0;

				switch (rtype) {
				case RDNS_REQUEST_A:
					if (inet_pton (AF_INET, str_rep, &rep->content.a.addr) != 1) {
						msg_err_config ("invalid A reply element for fake "
										"DNS record %s: %s",
								name, str_rep);
						free (rep);
					}
					else {
						DL_APPEND (replies, rep);
					}
					break;
				case RDNS_REQUEST_NS:
					rep->content.ns.name = strdup (str_rep);
					DL_APPEND (replies, rep);
					break;
				case RDNS_REQUEST_PTR:
					rep->content.ptr.name = strdup (str_rep);
					DL_APPEND (replies, rep);
					break;
				case RDNS_REQUEST_MX:
					svec = g_strsplit_set (str_rep, " :", -1);

					if (svec && svec[0] && svec[1]) {
						rep->content.mx.priority = strtoul (svec[0], NULL, 10);
						rep->content.mx.name = strdup (svec[1]);
						DL_APPEND (replies, rep);
					}
					else {
						msg_err_config ("invalid MX reply element for fake "
										"DNS record %s: %s",
								name, str_rep);
						free (rep);
					}

					g_strfreev (svec);
					break;
				case RDNS_REQUEST_TXT:
					rep->content.txt.data = strdup (str_rep);
					DL_APPEND (replies, rep);
					break;
				case RDNS_REQUEST_SOA:
					svec = g_strsplit_set (str_rep, " :", -1);

					/* 7 elements */
					if (svec && svec[0] && svec[1] && svec[2] &&
						svec[3] && svec[4] && svec[5] && svec[6]) {
						rep->content.soa.mname = strdup (svec[0]);
						rep->content.soa.admin = strdup (svec[1]);
						rep->content.soa.serial = strtoul (svec[2], NULL, 10);
						rep->content.soa.refresh = strtol (svec[3], NULL, 10);
						rep->content.soa.retry = strtol (svec[4], NULL, 10);
						rep->content.soa.expire = strtol (svec[5], NULL, 10);
						rep->content.soa.minimum = strtoul (svec[6], NULL, 10);
						DL_APPEND (replies, rep);
					}
					else {
						msg_err_config ("invalid MX reply element for fake "
										"DNS record %s: %s",
								name, str_rep);
						free (rep);
					}

					g_strfreev (svec);
					break;
				case RDNS_REQUEST_AAAA:
					if (inet_pton (AF_INET6, str_rep, &rep->content.aaa.addr) != 1) {
						msg_err_config ("invalid AAAA reply element for fake "
										"DNS record %s: %s",
								name, str_rep);
						free (rep);
					}
					else {
						DL_APPEND (replies, rep);
					}
				case RDNS_REQUEST_SRV:
				default:
					msg_err_config ("invalid or unsupported reply element "
									"for fake DNS record %s(%s): %s",
							name, rdns_str_from_type (rtype), str_rep);
					free (rep);
					break;
				}
			}

			ucl_object_iterate_free (rep_it);

			if (replies) {
				struct rdns_reply_entry *tmp_entry;
				guint i = 0;
				DL_COUNT (replies, tmp_entry, i);

				msg_info_config ("added fake record: %s(%s); %d replies", name,
						rdns_str_from_type (rtype), i);
				rdns_resolver_set_fake_reply (dns_resolver->r,
						name, rtype, rcode, replies);
			}
			else {
				msg_warn_config ("record %s has no replies, not adding",
						name);
			}
		}
		else {
			/* This entry returns some non valid code, no replies are possible */
			replies_obj = ucl_object_lookup (cur, "replies");

			if (replies_obj) {
				msg_warn_config ("replies are set for non-successful return "
								 "code for %s(%s), they will be ignored", name, rdns_str_from_type (rtype));
			}

			rdns_resolver_set_fake_reply (dns_resolver->r,
					name, rtype, rcode, NULL);
		}
	}

	ucl_object_iterate_free (it);
}

static bool
rspamd_dns_read_hosts_file (struct rspamd_config *cfg,
							struct rspamd_dns_resolver *dns_resolver,
							const gchar *fname)
{
	gchar *linebuf = NULL;
	gsize buflen = 0;
	gssize r;
	FILE *fp;
	guint nadded = 0;

	fp = fopen (fname, "r");

	if (fp == NULL) {
		/* Hack to reduce noise */
		if (strcmp (fname, "/etc/hosts") == 0) {
			msg_info_config ("cannot open hosts file %s: %s", fname,
					strerror (errno));
		}
		else {
			msg_err_config ("cannot open hosts file %s: %s", fname,
					strerror (errno));
		}

		return false;
	}

	while ((r = getline (&linebuf, &buflen, fp)) > 0) {
		if (linebuf[0] == '#' || g_ascii_isspace (linebuf[0])) {
			/* Skip comment or empty line */
			continue;
		}

		g_strchomp (linebuf);

		gchar **elts = g_strsplit_set (linebuf, " \t\v", -1);
		rspamd_inet_addr_t *addr;

		if (!rspamd_parse_inet_address (&addr, elts[0], strlen (elts[0]),
				RSPAMD_INET_ADDRESS_PARSE_REMOTE|RSPAMD_INET_ADDRESS_PARSE_NO_UNIX)) {
			msg_warn_config ("bad hosts file line: %s; cannot parse address", linebuf);
		}
		else {
			/* Add all FQDN + aliases if any */
			gchar **cur_name = &elts[1];

			while (*cur_name) {
				if (strlen (*cur_name) == 0) {
					cur_name ++;
					continue;
				}

				if (*cur_name[0] == '#') {
					/* Start of the comment */
					break;
				}

				struct rdns_reply_entry *rep;
				rep = calloc (1, sizeof (*rep));
				g_assert (rep != NULL);

				rep->ttl = 0;

				if (rspamd_inet_address_get_af (addr) == AF_INET) {
					socklen_t unused;
					const struct sockaddr_in *sin = (const struct sockaddr_in *)
							rspamd_inet_address_get_sa (addr, &unused);
					rep->type = RDNS_REQUEST_A;
					memcpy (&rep->content.a.addr, &sin->sin_addr,
							sizeof (rep->content.a.addr));
				}
				else {
					socklen_t unused;
					const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)
							rspamd_inet_address_get_sa (addr, &unused);
					rep->type = RDNS_REQUEST_AAAA;
					memcpy (&rep->content.aaa.addr, &sin6->sin6_addr,
							sizeof (rep->content.aaa.addr));
				}

				rep->next = NULL;
				rep->prev = rep;
				rdns_resolver_set_fake_reply (dns_resolver->r,
						g_strdup (*cur_name), rep->type, RDNS_RC_NOERROR, rep);
				msg_debug_config ("added fake record %s -> %s from hosts file %s",
						*cur_name, rspamd_inet_address_to_string (addr), fname);
				cur_name ++;
				nadded ++;
			}

			rspamd_inet_address_free (addr);
		}

		g_strfreev (elts);
	}

	msg_info_config ("processed host file %s; %d records added", fname, nadded);
	fclose (fp);

	return true;
}

static void
rspamd_dns_resolver_config_ucl (struct rspamd_config *cfg,
								struct rspamd_dns_resolver *dns_resolver,
								const ucl_object_t *dns_section)
{
	const ucl_object_t *fake_replies, *fails_cache_size, *fails_cache_time,
		*hosts;
	static const ev_tstamp default_fails_cache_time = 10.0;

	/* Process fake replies */
	fake_replies = ucl_object_lookup_any (dns_section, "fake_records",
			"fake_replies", NULL);

	if (fake_replies && ucl_object_type (fake_replies) == UCL_ARRAY) {
		const ucl_object_t *cur_arr;

		DL_FOREACH (fake_replies, cur_arr) {
			rspamd_process_fake_reply (cfg, dns_resolver, cur_arr);
		}
	}

	hosts = ucl_object_lookup (dns_section, "hosts");

	if (hosts == NULL) {
		/* Read normal `/etc/hosts` file */
		rspamd_dns_read_hosts_file (cfg, dns_resolver, "/etc/hosts");
	}
	else if (ucl_object_type (hosts) == UCL_NULL) {
		/* Do nothing, hosts are explicitly disabled */
	}
	else if (ucl_object_type (hosts) == UCL_STRING) {
		if (!rspamd_dns_read_hosts_file (cfg, dns_resolver, ucl_object_tostring (hosts))) {
			msg_err_config ("cannot read hosts file %s", ucl_object_tostring (hosts));
		}
	}
	else if (ucl_object_type (hosts) == UCL_ARRAY) {
		const ucl_object_t *cur;
		ucl_object_iter_t it = NULL;

		while ((cur = ucl_object_iterate (hosts, &it, true)) != NULL) {
			if (!rspamd_dns_read_hosts_file (cfg, dns_resolver, ucl_object_tostring (cur))) {
				msg_err_config ("cannot read hosts file %s", ucl_object_tostring (cur));
			}
		}
	}
	else {
		msg_err_config ("invalid type for hosts parameter: %s",
				ucl_object_type_to_string (ucl_object_type (hosts)));
	}

	fails_cache_size = ucl_object_lookup (dns_section, "fails_cache_size");
	if (fails_cache_size && ucl_object_type (fails_cache_size) == UCL_INT) {

		dns_resolver->fails_cache_time = default_fails_cache_time;
		fails_cache_time = ucl_object_lookup (dns_section, "fails_cache_time");

		if (fails_cache_time) {
			dns_resolver->fails_cache_time = ucl_object_todouble (fails_cache_time);
		}

		dns_resolver->fails_cache = rspamd_lru_hash_new_full (
				ucl_object_toint (fails_cache_size),
				g_free, (GDestroyNotify)rdns_request_release,
				rspamd_dns_fail_hash, rspamd_dns_fail_equal);
	}
}

struct rspamd_dns_resolver *
rspamd_dns_resolver_init (rspamd_logger_t *logger,
						  struct ev_loop *ev_base,
						  struct rspamd_config *cfg)
{
	struct rspamd_dns_resolver *dns_resolver;

	dns_resolver = g_malloc0 (sizeof (struct rspamd_dns_resolver));
	dns_resolver->event_loop = ev_base;
	if (cfg != NULL) {
		dns_resolver->request_timeout = cfg->dns_timeout;
		dns_resolver->max_retransmits = cfg->dns_retransmits;
	}
	else {
		dns_resolver->request_timeout = 1;
		dns_resolver->max_retransmits = 2;
	}

	dns_resolver->r = rdns_resolver_new ();
	rdns_bind_libev (dns_resolver->r, dns_resolver->event_loop);

	if (cfg != NULL) {
		rdns_resolver_set_log_level (dns_resolver->r, cfg->log_level);
		dns_resolver->cfg = cfg;
		rdns_resolver_set_dnssec (dns_resolver->r, cfg->enable_dnssec);

		if (cfg->nameservers == NULL) {
			/* Parse resolv.conf */
			dns_resolver->ups = rspamd_upstreams_create (cfg->ups_ctx);
			rspamd_upstreams_set_flags (dns_resolver->ups,
					RSPAMD_UPSTREAM_FLAG_NORESOLVE);
			rspamd_upstreams_set_rotation (dns_resolver->ups,
					RSPAMD_UPSTREAM_MASTER_SLAVE);

			if (!rdns_resolver_parse_resolv_conf_cb (dns_resolver->r,
					"/etc/resolv.conf",
					rspamd_dns_resolv_conf_on_server,
					dns_resolver)) {
				msg_err ("cannot parse resolv.conf and no nameservers defined, "
						"so no ways to resolve addresses");
				rdns_resolver_release (dns_resolver->r);
				dns_resolver->r = NULL;

				return dns_resolver;
			}

			/* Use normal resolv.conf rules */
			rspamd_upstreams_foreach (dns_resolver->ups, rspamd_dns_server_reorder,
					dns_resolver);
		}
		else {
			dns_resolver->ups = rspamd_upstreams_create (cfg->ups_ctx);
			rspamd_upstreams_set_flags (dns_resolver->ups,
					RSPAMD_UPSTREAM_FLAG_NORESOLVE);

			if (!rspamd_upstreams_from_ucl (dns_resolver->ups, cfg->nameservers,
					53, dns_resolver)) {
				msg_err_config ("cannot parse DNS nameservers definitions");
				rdns_resolver_release (dns_resolver->r);
				dns_resolver->r = NULL;

				return dns_resolver;
			}
		}

		rspamd_upstreams_foreach (dns_resolver->ups, rspamd_dns_server_init,
				dns_resolver);
		rdns_resolver_set_upstream_lib (dns_resolver->r, &rspamd_ups_ctx,
				dns_resolver->ups);
		cfg->dns_resolver = dns_resolver;

		if (cfg->rcl_obj) {
			/* Configure additional options */
			const ucl_object_t *opts_section, *dns_section, *tmp;

			opts_section = ucl_object_lookup (cfg->rcl_obj, "options");

			if (opts_section) {
				/* TODO: implement a more simple merge logic */
				DL_FOREACH (opts_section, tmp) {
					dns_section = ucl_object_lookup (opts_section, "dns");

					if (dns_section) {
						rspamd_dns_resolver_config_ucl (cfg, dns_resolver,
								dns_section);
					}
				}
			}
		}
	}

	rdns_resolver_set_logger (dns_resolver->r, rspamd_rnds_log_bridge, logger);
	rdns_resolver_init (dns_resolver->r);

	return dns_resolver;
}

void
rspamd_dns_resolver_deinit (struct rspamd_dns_resolver *resolver)
{
	if (resolver) {
		if (resolver->r) {
			rdns_resolver_release (resolver->r);
		}

		if (resolver->ups) {
			rspamd_upstreams_destroy (resolver->ups);
		}

		if (resolver->fails_cache) {
			rspamd_lru_hash_destroy (resolver->fails_cache);
		}

		g_free (resolver);
	}
}


static struct rdns_upstream_elt*
rspamd_dns_select_upstream (const char *name,
		size_t len, void *ups_data)
{
	struct upstream_list *ups = ups_data;
	struct upstream *up;

	up = rspamd_upstream_get (ups, RSPAMD_UPSTREAM_ROUND_ROBIN, name, len);

	if (up) {
		msg_debug ("select %s", rspamd_upstream_name (up));

		return rspamd_upstream_get_data (up);
	}

	return NULL;
}

static struct rdns_upstream_elt*
rspamd_dns_select_upstream_retransmit (
		const char *name,
		size_t len,
		struct rdns_upstream_elt *prev_elt,
		void *ups_data)
{
	struct upstream_list *ups = ups_data;
	struct upstream *up;

	if (prev_elt) {
		up = rspamd_upstream_get_except (ups, (struct upstream *)prev_elt->lib_data,
				RSPAMD_UPSTREAM_MASTER_SLAVE, name, len);
	}
	else {
		up = rspamd_upstream_get_forced (ups, RSPAMD_UPSTREAM_RANDOM, name, len);
	}

	if (up) {
		msg_debug ("select forced %s", rspamd_upstream_name (up));

		return rspamd_upstream_get_data (up);
	}

	return NULL;
}

static void
rspamd_dns_upstream_ok (struct rdns_upstream_elt *elt,
		void *ups_data)
{
	struct upstream *up = elt->lib_data;

	rspamd_upstream_ok (up);
}

static void
rspamd_dns_upstream_fail (struct rdns_upstream_elt *elt,
		void *ups_data, const gchar *reason)
{
	struct upstream *up = elt->lib_data;

	rspamd_upstream_fail (up, FALSE, reason);
}

static unsigned int
rspamd_dns_upstream_count (void *ups_data)
{
	struct upstream_list *ups = ups_data;

	return rspamd_upstreams_alive (ups);
}