Adding upstream version 2.9.5.upstream/2.9.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3813 insertions, 0 deletions

diff --git a/src/resolvers.c b/src/resolvers.c
new file mode 100644
index 0000000..3275cd2
--- /dev/null
+++ b/src/resolvers.c
@@ -0,0 +1,3813 @@
+/*
+ * Name server resolution
+ *
+ * Copyright 2014 Baptiste Assmann <bedis9@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
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+
+#include <import/ebistree.h>
+
+#include <haproxy/action.h>
+#include <haproxy/api.h>
+#include <haproxy/applet.h>
+#include <haproxy/cfgparse.h>
+#include <haproxy/channel.h>
+#include <haproxy/check.h>
+#include <haproxy/cli.h>
+#include <haproxy/dns.h>
+#include <haproxy/errors.h>
+#include <haproxy/fd.h>
+#include <haproxy/http_rules.h>
+#include <haproxy/log.h>
+#include <haproxy/net_helper.h>
+#include <haproxy/protocol.h>
+#include <haproxy/proxy.h>
+#include <haproxy/resolvers.h>
+#include <haproxy/ring.h>
+#include <haproxy/sample.h>
+#include <haproxy/sc_strm.h>
+#include <haproxy/server.h>
+#include <haproxy/stats.h>
+#include <haproxy/stconn.h>
+#include <haproxy/task.h>
+#include <haproxy/tcp_rules.h>
+#include <haproxy/ticks.h>
+#include <haproxy/time.h>
+#include <haproxy/tools.h>
+#include <haproxy/vars.h>
+#include <haproxy/xxhash.h>
+
+
+struct list sec_resolvers  = LIST_HEAD_INIT(sec_resolvers);
+struct list resolv_srvrq_list = LIST_HEAD_INIT(resolv_srvrq_list);
+
+static THREAD_LOCAL struct list death_row; /* list of deferred resolutions to kill, local validity only */
+static THREAD_LOCAL unsigned int recurse = 0; /* counter to track calls to public functions */
+static THREAD_LOCAL uint64_t resolv_query_id_seed = 0; /* random seed */
+struct resolvers *curr_resolvers = NULL;
+
+DECLARE_STATIC_POOL(resolv_answer_item_pool, "resolv_answer_item", sizeof(struct resolv_answer_item));
+DECLARE_STATIC_POOL(resolv_resolution_pool,  "resolv_resolution",  sizeof(struct resolv_resolution));
+DECLARE_POOL(resolv_requester_pool,  "resolv_requester",  sizeof(struct resolv_requester));
+
+static unsigned int resolution_uuid = 1;
+unsigned int resolv_failed_resolutions = 0;
+struct task *process_resolvers(struct task *t, void *context, unsigned int state);
+static void resolv_free_resolution(struct resolv_resolution *resolution);
+static void _resolv_unlink_resolution(struct resolv_requester *requester);
+static void enter_resolver_code();
+static void leave_resolver_code();
+
+enum {
+	RSLV_STAT_ID,
+	RSLV_STAT_PID,
+	RSLV_STAT_SENT,
+	RSLV_STAT_SND_ERROR,
+	RSLV_STAT_VALID,
+	RSLV_STAT_UPDATE,
+	RSLV_STAT_CNAME,
+	RSLV_STAT_CNAME_ERROR,
+	RSLV_STAT_ANY_ERR,
+	RSLV_STAT_NX,
+	RSLV_STAT_TIMEOUT,
+	RSLV_STAT_REFUSED,
+	RSLV_STAT_OTHER,
+	RSLV_STAT_INVALID,
+	RSLV_STAT_TOO_BIG,
+	RSLV_STAT_TRUNCATED,
+	RSLV_STAT_OUTDATED,
+	RSLV_STAT_END,
+};
+
+static struct name_desc resolv_stats[] = {
+	[RSLV_STAT_ID]          = { .name = "id",          .desc = "ID" },
+	[RSLV_STAT_PID]         = { .name = "pid",         .desc = "Parent ID" },
+	[RSLV_STAT_SENT]        = { .name = "sent",        .desc = "Sent" },
+	[RSLV_STAT_SND_ERROR]   = { .name = "send_error",  .desc = "Send error" },
+	[RSLV_STAT_VALID]       = { .name = "valid",       .desc = "Valid" },
+	[RSLV_STAT_UPDATE]      = { .name = "update",      .desc = "Update" },
+	[RSLV_STAT_CNAME]       = { .name = "cname",       .desc = "CNAME" },
+	[RSLV_STAT_CNAME_ERROR] = { .name = "cname_error", .desc = "CNAME error" },
+	[RSLV_STAT_ANY_ERR]     = { .name = "any_err",     .desc = "Any errors" },
+	[RSLV_STAT_NX]          = { .name = "nx",          .desc = "NX" },
+	[RSLV_STAT_TIMEOUT]     = { .name = "timeout",     .desc = "Timeout" },
+	[RSLV_STAT_REFUSED]     = { .name = "refused",     .desc = "Refused" },
+	[RSLV_STAT_OTHER]       = { .name = "other",       .desc = "Other" },
+	[RSLV_STAT_INVALID]     = { .name = "invalid",     .desc = "Invalid" },
+	[RSLV_STAT_TOO_BIG]     = { .name = "too_big",     .desc = "Too big" },
+	[RSLV_STAT_TRUNCATED]   = { .name = "truncated",   .desc = "Truncated" },
+	[RSLV_STAT_OUTDATED]    = { .name = "outdated",    .desc = "Outdated" },
+};
+
+static struct dns_counters dns_counters;
+
+static void resolv_fill_stats(void *d, struct field *stats)
+{
+	struct dns_counters *counters = d;
+	stats[RSLV_STAT_ID]          = mkf_str(FO_CONFIG, counters->id);
+	stats[RSLV_STAT_PID]         = mkf_str(FO_CONFIG, counters->pid);
+	stats[RSLV_STAT_SENT]        = mkf_u64(FN_GAUGE, counters->sent);
+	stats[RSLV_STAT_SND_ERROR]   = mkf_u64(FN_GAUGE, counters->snd_error);
+	stats[RSLV_STAT_VALID]       = mkf_u64(FN_GAUGE, counters->app.resolver.valid);
+	stats[RSLV_STAT_UPDATE]      = mkf_u64(FN_GAUGE, counters->app.resolver.update);
+	stats[RSLV_STAT_CNAME]       = mkf_u64(FN_GAUGE, counters->app.resolver.cname);
+	stats[RSLV_STAT_CNAME_ERROR] = mkf_u64(FN_GAUGE, counters->app.resolver.cname_error);
+	stats[RSLV_STAT_ANY_ERR]     = mkf_u64(FN_GAUGE, counters->app.resolver.any_err);
+	stats[RSLV_STAT_NX]          = mkf_u64(FN_GAUGE, counters->app.resolver.nx);
+	stats[RSLV_STAT_TIMEOUT]     = mkf_u64(FN_GAUGE, counters->app.resolver.timeout);
+	stats[RSLV_STAT_REFUSED]     = mkf_u64(FN_GAUGE, counters->app.resolver.refused);
+	stats[RSLV_STAT_OTHER]       = mkf_u64(FN_GAUGE, counters->app.resolver.other);
+	stats[RSLV_STAT_INVALID]     = mkf_u64(FN_GAUGE, counters->app.resolver.invalid);
+	stats[RSLV_STAT_TOO_BIG]     = mkf_u64(FN_GAUGE, counters->app.resolver.too_big);
+	stats[RSLV_STAT_TRUNCATED]   = mkf_u64(FN_GAUGE, counters->app.resolver.truncated);
+	stats[RSLV_STAT_OUTDATED]    = mkf_u64(FN_GAUGE, counters->app.resolver.outdated);
+}
+
+static struct stats_module rslv_stats_module = {
+	.name          = "resolvers",
+	.domain_flags  = STATS_DOMAIN_RESOLVERS << STATS_DOMAIN,
+	.fill_stats    = resolv_fill_stats,
+	.stats         = resolv_stats,
+	.stats_count   = RSLV_STAT_END,
+	.counters      = &dns_counters,
+	.counters_size = sizeof(dns_counters),
+	.clearable     = 0,
+};
+
+INITCALL1(STG_REGISTER, stats_register_module, &rslv_stats_module);
+
+/* CLI context used during "show resolvers" */
+struct show_resolvers_ctx {
+	struct resolvers *forced_section;
+	struct resolvers *resolvers;
+	struct dns_nameserver *ns;
+};
+
+/* Returns a pointer to the resolvers matching the id <id>. NULL is returned if
+ * no match is found.
+ */
+struct resolvers *find_resolvers_by_id(const char *id)
+{
+	struct resolvers *res;
+
+	list_for_each_entry(res, &sec_resolvers, list) {
+		if (strcmp(res->id, id) == 0)
+			return res;
+	}
+	return NULL;
+}
+
+/* Returns a pointer on the SRV request matching the name <name> for the proxy
+ * <px>. NULL is returned if no match is found.
+ */
+struct resolv_srvrq *find_srvrq_by_name(const char *name, struct proxy *px)
+{
+	struct resolv_srvrq *srvrq;
+
+	list_for_each_entry(srvrq, &resolv_srvrq_list, list) {
+		if (srvrq->proxy == px && strcmp(srvrq->name, name) == 0)
+			return srvrq;
+	}
+	return NULL;
+}
+
+/* Allocates a new SRVRQ for the given server with the name <fqdn>. It returns
+ * NULL if an error occurred. */
+struct resolv_srvrq *new_resolv_srvrq(struct server *srv, char *fqdn)
+{
+	struct proxy     *px    = srv->proxy;
+	struct resolv_srvrq *srvrq = NULL;
+	int fqdn_len, hostname_dn_len;
+
+	fqdn_len = strlen(fqdn);
+	hostname_dn_len = resolv_str_to_dn_label(fqdn, fqdn_len, trash.area,
+					      trash.size);
+	if (hostname_dn_len == -1) {
+		ha_alert("%s '%s', server '%s': failed to parse FQDN '%s'\n",
+			 proxy_type_str(px), px->id, srv->id, fqdn);
+		goto err;
+	}
+
+	if ((srvrq = calloc(1, sizeof(*srvrq))) == NULL) {
+		ha_alert("%s '%s', server '%s': out of memory\n",
+			 proxy_type_str(px), px->id, srv->id);
+		goto err;
+	}
+	srvrq->obj_type        = OBJ_TYPE_SRVRQ;
+	srvrq->proxy           = px;
+	srvrq->name            = strdup(fqdn);
+	srvrq->hostname_dn     = strdup(trash.area);
+	srvrq->hostname_dn_len = hostname_dn_len;
+	if (!srvrq->name || !srvrq->hostname_dn) {
+		ha_alert("%s '%s', server '%s': out of memory\n",
+			 proxy_type_str(px), px->id, srv->id);
+		goto err;
+	}
+	LIST_INIT(&srvrq->attached_servers);
+	srvrq->named_servers = EB_ROOT;
+	LIST_APPEND(&resolv_srvrq_list, &srvrq->list);
+	return srvrq;
+
+  err:
+	if (srvrq) {
+		free(srvrq->name);
+		free(srvrq->hostname_dn);
+		free(srvrq);
+	}
+	return NULL;
+}
+
+
+/* finds and return the SRV answer item associated to a requester (whose type is 'server').
+ *
+ * returns NULL in case of error or not found.
+ */
+struct resolv_answer_item *find_srvrq_answer_record(const struct resolv_requester *requester)
+{
+	struct resolv_resolution *res;
+	struct eb32_node *eb32;
+	struct server *srv;
+
+	if (!requester)
+		return NULL;
+
+	if ((srv = objt_server(requester->owner)) == NULL)
+		return NULL;
+	/* check if the server is managed by a SRV record */
+	if (srv->srvrq == NULL)
+		return NULL;
+
+	res = srv->srvrq->requester->resolution;
+
+	/* search an ANSWER record whose target points to the server's hostname and whose port is
+	 * the same as server's svc_port */
+	for (eb32 = eb32_first(&res->response.answer_tree); eb32 != NULL;  eb32 = eb32_next(eb32)) {
+		struct resolv_answer_item *item = eb32_entry(eb32, typeof(*item), link);
+
+		if (memcmp(srv->hostname_dn, item->data.target, srv->hostname_dn_len) == 0 &&
+		    (srv->svc_port == item->port))
+			return item;
+	}
+
+	return NULL;
+}
+
+/* 2 bytes random generator to generate DNS query ID */
+static inline uint16_t resolv_rnd16(void)
+{
+	if (!resolv_query_id_seed)
+		resolv_query_id_seed = now_ms;
+	resolv_query_id_seed ^= resolv_query_id_seed << 13;
+	resolv_query_id_seed ^= resolv_query_id_seed >> 7;
+	resolv_query_id_seed ^= resolv_query_id_seed << 17;
+	return resolv_query_id_seed;
+}
+
+
+static inline int resolv_resolution_timeout(struct resolv_resolution *res)
+{
+	return res->resolvers->timeout.resolve;
+}
+
+/* Updates a resolvers' task timeout for next wake up and queue it */
+static void resolv_update_resolvers_timeout(struct resolvers *resolvers)
+{
+	struct resolv_resolution *res;
+	int next = TICK_ETERNITY;
+
+	if (!LIST_ISEMPTY(&resolvers->resolutions.curr)) {
+		res  = LIST_NEXT(&resolvers->resolutions.curr, struct resolv_resolution *, list);
+		next = tick_add(now_ms, resolvers->timeout.resolve);
+		next = tick_first(next, tick_add(res->last_query, resolvers->timeout.retry));
+	}
+
+	list_for_each_entry(res, &resolvers->resolutions.wait, list)
+		next = tick_first(next, tick_add(res->last_resolution, resolv_resolution_timeout(res)));
+
+	resolvers->t->expire = next;
+	task_queue(resolvers->t);
+}
+
+/* Forges a DNS query. It needs the following information from the caller:
+ *  - <query_id>        : the DNS query id corresponding to this query
+ *  - <query_type>      : DNS_RTYPE_* request DNS record type (A, AAAA, ANY...)
+ *  - <hostname_dn>     : hostname in domain name format
+ *  - <hostname_dn_len> : length of <hostname_dn>
+ *
+ * To store the query, the caller must pass a buffer <buf> and its size
+ * <bufsize>. It returns the number of written bytes in success, -1 if <buf> is
+ * too short.
+ */
+static int resolv_build_query(int query_id, int query_type, unsigned int accepted_payload_size,
+                              char *hostname_dn, int hostname_dn_len, char *buf, int bufsize)
+{
+	struct dns_header            dns_hdr;
+	struct dns_question          qinfo;
+	struct dns_additional_record edns;
+	char *p = buf;
+
+	if (sizeof(dns_hdr) + sizeof(qinfo) +  sizeof(edns) + hostname_dn_len >= bufsize)
+		return -1;
+
+	memset(buf, 0, bufsize);
+
+	/* Set dns query headers */
+	dns_hdr.id      = (unsigned short) htons(query_id);
+	dns_hdr.flags   = htons(0x0100); /* qr=0, opcode=0, aa=0, tc=0, rd=1, ra=0, z=0, rcode=0 */
+	dns_hdr.qdcount = htons(1);      /* 1 question */
+	dns_hdr.ancount = 0;
+	dns_hdr.nscount = 0;
+	dns_hdr.arcount = htons(1);
+	memcpy(p, &dns_hdr, sizeof(dns_hdr));
+	p += sizeof(dns_hdr);
+
+	/* Set up query hostname */
+	memcpy(p, hostname_dn, hostname_dn_len);
+	p += hostname_dn_len;
+	*p++ = 0;
+
+	/* Set up query info (type and class) */
+	qinfo.qtype  = htons(query_type);
+	qinfo.qclass = htons(DNS_RCLASS_IN);
+	memcpy(p, &qinfo, sizeof(qinfo));
+	p += sizeof(qinfo);
+
+	/* Set the DNS extension */
+	edns.name             = 0;
+	edns.type             = htons(DNS_RTYPE_OPT);
+	edns.udp_payload_size = htons(accepted_payload_size);
+	edns.extension        = 0;
+	edns.data_length      = 0;
+	memcpy(p, &edns, sizeof(edns));
+	p += sizeof(edns);
+
+	return (p - buf);
+}
+
+/* Sends a DNS query to resolvers associated to a resolution. It returns 0 on
+ * success or -1 if trash buffer is not large enough to build a valid query.
+ */
+static int resolv_send_query(struct resolv_resolution *resolution)
+{
+	struct resolvers  *resolvers = resolution->resolvers;
+	struct dns_nameserver *ns;
+	int len;
+
+	/* Update resolution */
+	resolution->nb_queries   = 0;
+	resolution->nb_responses = 0;
+	resolution->last_query   = now_ms;
+
+	len = resolv_build_query(resolution->query_id, resolution->query_type,
+	                      resolvers->accepted_payload_size,
+	                      resolution->hostname_dn, resolution->hostname_dn_len,
+	                      trash.area, trash.size);
+	if (len < 0) {
+		send_log(NULL, LOG_NOTICE,
+			 "can not build the query message for %s, in resolvers %s.\n",
+			 resolution->hostname_dn, resolvers->id);
+		return -1;
+	}
+
+	list_for_each_entry(ns, &resolvers->nameservers, list) {
+		if (dns_send_nameserver(ns, trash.area, len) >= 0)
+			resolution->nb_queries++;
+	}
+
+	/* Push the resolution at the end of the active list */
+	LIST_DEL_INIT(&resolution->list);
+	LIST_APPEND(&resolvers->resolutions.curr, &resolution->list);
+	return 0;
+}
+
+/* Prepares and sends a DNS resolution. It returns 1 if the query was sent, 0 if
+ * skipped and -1 if an error occurred.
+ */
+static int
+resolv_run_resolution(struct resolv_resolution *resolution)
+{
+	struct resolvers  *resolvers = resolution->resolvers;
+	int query_id, i;
+
+	/* Avoid sending requests for resolutions that don't yet have an
+	 * hostname, ie resolutions linked to servers that do not yet have an
+	 * fqdn */
+	if (!resolution->hostname_dn)
+		return 0;
+
+	/* Check if a resolution has already been started for this server return
+	 * directly to avoid resolution pill up. */
+	if (resolution->step != RSLV_STEP_NONE)
+		return 0;
+
+	/* Generates a new query id. We try at most 100 times to find a free
+	 * query id */
+	for (i = 0; i < 100; ++i) {
+		query_id = resolv_rnd16();
+		if (!eb32_lookup(&resolvers->query_ids, query_id))
+			break;
+		query_id = -1;
+	}
+	if (query_id == -1) {
+		send_log(NULL, LOG_NOTICE,
+			 "could not generate a query id for %s, in resolvers %s.\n",
+			 resolution->hostname_dn, resolvers->id);
+		return -1;
+	}
+
+	/* Update resolution parameters */
+	resolution->query_id     = query_id;
+	resolution->qid.key      = query_id;
+	resolution->step         = RSLV_STEP_RUNNING;
+	resolution->query_type   = resolution->prefered_query_type;
+	resolution->try          = resolvers->resolve_retries;
+	eb32_insert(&resolvers->query_ids, &resolution->qid);
+
+	/* Send the DNS query */
+	resolution->try -= 1;
+	resolv_send_query(resolution);
+	return 1;
+}
+
+/* Performs a name resolution for the requester <req> */
+void resolv_trigger_resolution(struct resolv_requester *req)
+{
+	struct resolvers  *resolvers;
+	struct resolv_resolution *res;
+	int exp;
+
+	if (!req || !req->resolution)
+		return;
+	res       = req->resolution;
+	resolvers = res->resolvers;
+
+	enter_resolver_code();
+
+	/* The resolution must not be triggered yet. Use the cached response, if
+	 * valid */
+	exp = tick_add(res->last_resolution, resolvers->hold.valid);
+	if (resolvers->t && (!tick_isset(resolvers->t->expire) || res->status != RSLV_STATUS_VALID ||
+	    !tick_isset(res->last_resolution) || tick_is_expired(exp, now_ms))) {
+		/* If the resolution is not running and the requester is a
+		 * server, reset the resolution timer to force a quick
+		 * resolution.
+		 */
+		if (res->step == RSLV_STEP_NONE &&
+		    (obj_type(req->owner) == OBJ_TYPE_SERVER ||
+		     obj_type(req->owner) == OBJ_TYPE_SRVRQ))
+			res->last_resolution = TICK_ETERNITY;
+		task_wakeup(resolvers->t, TASK_WOKEN_OTHER);
+	}
+
+	leave_resolver_code();
+}
+
+
+/* Resets some resolution parameters to initial values and also delete the query
+ * ID from the resolver's tree.
+ */
+static void resolv_reset_resolution(struct resolv_resolution *resolution)
+{
+	/* update resolution status */
+	resolution->step            = RSLV_STEP_NONE;
+	resolution->try             = 0;
+	resolution->last_resolution = now_ms;
+	resolution->nb_queries      = 0;
+	resolution->nb_responses    = 0;
+	resolution->query_type      = resolution->prefered_query_type;
+
+	/* clean up query id */
+	eb32_delete(&resolution->qid);
+	resolution->query_id = 0;
+	resolution->qid.key   = 0;
+}
+
+/* Returns the query id contained in a DNS response */
+static inline unsigned short resolv_response_get_query_id(unsigned char *resp)
+{
+	return resp[0] * 256 + resp[1];
+}
+
+
+/* Analyses, re-builds and copies the name <name> from the DNS response packet
+ * <buffer>.  <name> must point to the 'data_len' information or pointer 'c0'
+ * for compressed data.  The result is copied into <dest>, ensuring we don't
+ * overflow using <dest_len> Returns the number of bytes the caller can move
+ * forward. If 0 it means an error occurred while parsing the name. <offset> is
+ * the number of bytes the caller could move forward.
+ */
+int resolv_read_name(unsigned char *buffer, unsigned char *bufend,
+		     unsigned char *name, char *destination, int dest_len,
+		     int *offset, unsigned int depth)
+{
+	int nb_bytes = 0, n = 0;
+	int label_len;
+	unsigned char *reader = name;
+	char *dest = destination;
+
+	while (1) {
+		if (reader >= bufend)
+			goto err;
+
+		/* Name compression is in use */
+		if ((*reader & 0xc0) == 0xc0) {
+			if (reader + 1 >= bufend)
+				goto err;
+
+			/* Must point BEFORE current position */
+			if ((buffer + reader[1]) > reader)
+				goto err;
+
+			if (depth++ > 100)
+				goto err;
+
+			n = resolv_read_name(buffer, bufend, buffer + (*reader & 0x3f)*256 + reader[1],
+			                     dest, dest_len - nb_bytes, offset, depth);
+			if (n == 0)
+				goto err;
+
+			dest     += n;
+			nb_bytes += n;
+			goto out;
+		}
+
+		label_len = *reader;
+		if (label_len == 0)
+			goto out;
+
+		/* Check if:
+		 *  - we won't read outside the buffer
+		 *  - there is enough place in the destination
+		 */
+		if ((reader + label_len >= bufend) || (nb_bytes + label_len >= dest_len))
+			goto err;
+
+		/* +1 to take label len + label string */
+		label_len++;
+
+		memcpy(dest, reader, label_len);
+
+		dest     += label_len;
+		nb_bytes += label_len;
+		reader   += label_len;
+	}
+
+  out:
+	/* offset computation:
+	 * parse from <name> until finding either NULL or a pointer "c0xx"
+	 */
+	reader  = name;
+	*offset = 0;
+	while (reader < bufend) {
+		if ((reader[0] & 0xc0) == 0xc0) {
+			*offset += 2;
+			break;
+		}
+		else if (*reader == 0) {
+			*offset += 1;
+			break;
+		}
+		*offset += 1;
+		++reader;
+	}
+	return nb_bytes;
+
+  err:
+	return 0;
+}
+
+/* Reinitialize the list of aborted resolutions before calling certain
+ * functions relying on it. The list must be processed by calling
+ * leave_resolver_code() after operations.
+ */
+static void enter_resolver_code()
+{
+	if (!recurse)
+		LIST_INIT(&death_row);
+	recurse++;
+}
+
+/* Add a resolution to the death_row. */
+static void abort_resolution(struct resolv_resolution *res)
+{
+	/* Remove the resolution from query_ids tree and from any resolvers list */
+	eb32_delete(&res->qid);
+	res->query_id = 0;
+	res->qid.key   = 0;
+
+	LIST_DEL_INIT(&res->list);
+	LIST_APPEND(&death_row, &res->list);
+}
+
+/* This releases any aborted resolution found in the death row. It is mandatory
+ * to call enter_resolver_code() first before the function (or loop) that
+ * needs to defer deletions. Note that some of them are in relation via internal
+ * objects and might cause the deletion of other ones from the same list, so we
+ * must absolutely not use a list_for_each_entry_safe() nor any such thing here,
+ * and solely rely on each call to remove the first remaining list element.
+ */
+static void leave_resolver_code()
+{
+	struct resolv_resolution *res;
+
+	recurse--;
+	if (recurse)
+		return;
+
+	while (!LIST_ISEMPTY(&death_row)) {
+		res = LIST_NEXT(&death_row, struct resolv_resolution *, list);
+		resolv_free_resolution(res);
+	}
+
+	/* make sure nobody tries to add anything without having initialized it */
+	death_row = (struct list){ };
+}
+
+/* Cleanup fqdn/port and address of a server attached to a SRV resolution. This
+ * happens when an SRV item is purged or when the server status is considered as
+ * obsolete.
+ *
+ * Must be called with the DNS lock held, and with the death_row already
+ * initialized via enter_resolver_code().
+ */
+static void resolv_srvrq_cleanup_srv(struct server *srv)
+{
+	_resolv_unlink_resolution(srv->resolv_requester);
+	HA_SPIN_LOCK(SERVER_LOCK, &srv->lock);
+	srvrq_update_srv_status(srv, 1);
+	ha_free(&srv->hostname);
+	ha_free(&srv->hostname_dn);
+	srv->hostname_dn_len = 0;
+	memset(&srv->addr, 0, sizeof(srv->addr));
+	srv->svc_port = 0;
+	srv->flags |= SRV_F_NO_RESOLUTION;
+
+	ebpt_delete(&srv->host_dn);
+	ha_free(&srv->host_dn.key);
+
+	HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
+	LIST_DEL_INIT(&srv->srv_rec_item);
+	LIST_APPEND(&srv->srvrq->attached_servers, &srv->srv_rec_item);
+
+	srv->srvrq_check->expire = TICK_ETERNITY;
+}
+
+/* Takes care to cleanup a server resolution when it is outdated. This only
+ * happens for a server relying on a SRV record.
+ */
+static struct task *resolv_srvrq_expire_task(struct task *t, void *context, unsigned int state)
+{
+	struct server *srv = context;
+
+	if (!tick_is_expired(t->expire, now_ms))
+		goto end;
+
+	enter_resolver_code();
+	HA_SPIN_LOCK(DNS_LOCK, &srv->srvrq->resolvers->lock);
+	resolv_srvrq_cleanup_srv(srv);
+	HA_SPIN_UNLOCK(DNS_LOCK, &srv->srvrq->resolvers->lock);
+	leave_resolver_code();
+
+  end:
+	return t;
+}
+
+/* Checks for any obsolete record, also identify any SRV request, and try to
+ * find a corresponding server.
+ */
+static void resolv_check_response(struct resolv_resolution *res)
+{
+	struct resolvers   *resolvers = res->resolvers;
+	struct resolv_requester   *req;
+	struct eb32_node          *eb32, *eb32_back;
+	struct server          *srv, *srvback;
+	struct resolv_srvrq       *srvrq;
+
+	for (eb32 = eb32_first(&res->response.answer_tree); eb32 && (eb32_back = eb32_next(eb32), 1); eb32 = eb32_back) {
+		struct resolv_answer_item *item = eb32_entry(eb32, typeof(*item), link);
+		struct resolv_answer_item *ar_item = item->ar_item;
+
+		/* clean up obsolete Additional record */
+		if (ar_item && tick_is_lt(tick_add(ar_item->last_seen, resolvers->hold.obsolete), now_ms)) {
+			/* Cleaning up the AR item will trigger an extra DNS  resolution, except if the SRV
+			 * item is also obsolete.
+			 */
+			pool_free(resolv_answer_item_pool, ar_item);
+			item->ar_item = NULL;
+		}
+
+		/* Remove obsolete items */
+		if (tick_is_lt(tick_add(item->last_seen, resolvers->hold.obsolete), now_ms)) {
+			if (item->type == DNS_RTYPE_A || item->type == DNS_RTYPE_AAAA) {
+				/* Remove any associated server */
+				list_for_each_entry_safe(srv, srvback, &item->attached_servers, ip_rec_item) {
+					LIST_DEL_INIT(&srv->ip_rec_item);
+				}
+			}
+			else if (item->type == DNS_RTYPE_SRV) {
+				/* Remove any associated server */
+				list_for_each_entry_safe(srv, srvback, &item->attached_servers, srv_rec_item)
+					resolv_srvrq_cleanup_srv(srv);
+			}
+
+			eb32_delete(&item->link);
+			if (item->ar_item) {
+				pool_free(resolv_answer_item_pool, item->ar_item);
+				item->ar_item = NULL;
+			}
+			pool_free(resolv_answer_item_pool, item);
+			continue;
+		}
+
+		if (item->type != DNS_RTYPE_SRV)
+			continue;
+
+		/* Now process SRV records */
+		list_for_each_entry(req, &res->requesters, list) {
+			struct ebpt_node *node;
+			char target[DNS_MAX_NAME_SIZE+1];
+
+			int i;
+			if ((srvrq = objt_resolv_srvrq(req->owner)) == NULL)
+				continue;
+
+			/* Check if a server already uses that record */
+			srv = NULL;
+			list_for_each_entry(srv, &item->attached_servers, srv_rec_item) {
+				if (srv->srvrq == srvrq) {
+					HA_SPIN_LOCK(SERVER_LOCK, &srv->lock);
+					goto srv_found;
+				}
+			}
+
+
+			/* If not empty we try to match a server
+			 * in server state file tree with the same hostname
+			 */
+			if (!eb_is_empty(&srvrq->named_servers)) {
+				srv = NULL;
+
+				/* convert the key to lookup in lower case */
+				for (i = 0 ; item->data.target[i] ; i++)
+					target[i] = tolower(item->data.target[i]);
+				target[i] = 0;
+
+				node = ebis_lookup(&srvrq->named_servers, target);
+				if (node) {
+					srv = ebpt_entry(node, struct server, host_dn);
+					HA_SPIN_LOCK(SERVER_LOCK, &srv->lock);
+
+					/* an entry was found with the same hostname
+					 * let check this node if the port matches
+					 * and try next node if the hostname
+					 * is still the same
+					 */
+					while (1) {
+						if (srv->svc_port == item->port) {
+							/* server found, we remove it from tree */
+							ebpt_delete(node);
+							ha_free(&srv->host_dn.key);
+							goto srv_found;
+						}
+
+						HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
+
+						node = ebpt_next(node);
+						if (!node)
+							break;
+
+						srv = ebpt_entry(node, struct server, host_dn);
+						HA_SPIN_LOCK(SERVER_LOCK, &srv->lock);
+
+						if ((item->data_len != srv->hostname_dn_len)
+						    || memcmp(srv->hostname_dn, item->data.target, item->data_len) != 0) {
+							HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
+							break;
+						}
+					}
+				}
+			}
+
+			/* Pick the first server listed in srvrq (those ones don't
+			 * have hostname and are free to use)
+			 */
+			srv = NULL;
+			list_for_each_entry(srv, &srvrq->attached_servers, srv_rec_item) {
+				LIST_DEL_INIT(&srv->srv_rec_item);
+				HA_SPIN_LOCK(SERVER_LOCK, &srv->lock);
+				goto srv_found;
+			}
+			srv = NULL;
+
+srv_found:
+			/* And update this server, if found (srv is locked here) */
+			if (srv) {
+				/* re-enable DNS resolution for this server by default */
+				srv->flags &= ~SRV_F_NO_RESOLUTION;
+				srv->srvrq_check->expire = TICK_ETERNITY;
+
+				srv->svc_port = item->port;
+				srv->flags   &= ~SRV_F_MAPPORTS;
+
+				/* Check if an Additional Record is associated to this SRV record.
+				 * Perform some sanity checks too to ensure the record can be used.
+				 * If all fine, we simply pick up the IP address found and associate
+				 * it to the server. And DNS resolution is disabled for this server.
+				 */
+				if ((item->ar_item != NULL) &&
+				    (item->ar_item->type == DNS_RTYPE_A || item->ar_item->type == DNS_RTYPE_AAAA))
+				{
+
+					switch (item->ar_item->type) {
+						case DNS_RTYPE_A:
+							srv_update_addr(srv, &item->ar_item->data.in4.sin_addr, AF_INET, "DNS additional record");
+						break;
+						case DNS_RTYPE_AAAA:
+							srv_update_addr(srv, &item->ar_item->data.in6.sin6_addr, AF_INET6, "DNS additional record");
+						break;
+					}
+
+					srv->flags |= SRV_F_NO_RESOLUTION;
+
+					/* Unlink A/AAAA resolution for this server if there is an AR item.
+					 * It is usless to perform an extra resolution
+					 */
+					_resolv_unlink_resolution(srv->resolv_requester);
+				}
+
+				if (!srv->hostname_dn) {
+					const char *msg = NULL;
+					char hostname[DNS_MAX_NAME_SIZE+1];
+
+					if (resolv_dn_label_to_str(item->data.target, item->data_len,
+					                           hostname, sizeof(hostname)) == -1) {
+						HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
+						continue;
+					}
+					msg = srv_update_fqdn(srv, hostname, "SRV record", 1);
+					if (msg)
+						send_log(srv->proxy, LOG_NOTICE, "%s", msg);
+				}
+
+				if (!LIST_INLIST(&srv->srv_rec_item))
+					LIST_APPEND(&item->attached_servers, &srv->srv_rec_item);
+
+				if (!(srv->flags & SRV_F_NO_RESOLUTION)) {
+					/* If there is no AR item responsible of the FQDN resolution,
+					 * trigger a dedicated DNS resolution
+					 */
+					if (!srv->resolv_requester || !srv->resolv_requester->resolution)
+						resolv_link_resolution(srv, OBJ_TYPE_SERVER, 1);
+				}
+
+				/* Update the server status */
+				srvrq_update_srv_status(srv, (srv->addr.ss_family != AF_INET && srv->addr.ss_family != AF_INET6));
+
+				if (!srv->resolv_opts.ignore_weight) {
+					char weight[9];
+					int ha_weight;
+
+					/* DNS weight range if from 0 to 65535
+					 * HAProxy weight is from 0 to 256
+					 * The rule below ensures that weight 0 is well respected
+					 * while allowing a "mapping" from DNS weight into HAProxy's one.
+					 */
+					ha_weight = (item->weight + 255) / 256;
+
+					snprintf(weight, sizeof(weight), "%d", ha_weight);
+					server_parse_weight_change_request(srv, weight);
+				}
+				HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
+			}
+		}
+	}
+}
+
+/* Validates that the buffer DNS response provided in <resp> and finishing
+ * before <bufend> is valid from a DNS protocol point of view.
+ *
+ * The result is stored in <resolution>' response, buf_response,
+ * response_query_records and response_answer_records members.
+ *
+ * This function returns one of the RSLV_RESP_* code to indicate the type of
+ * error found.
+ */
+static int resolv_validate_dns_response(unsigned char *resp, unsigned char *bufend,
+                                        struct resolv_resolution *resolution, int max_answer_records)
+{
+	unsigned char *reader;
+	char *previous_dname, tmpname[DNS_MAX_NAME_SIZE];
+	int len, flags, offset;
+	int nb_saved_records;
+	struct resolv_query_item *query;
+	struct resolv_answer_item *answer_record, *tmp_record;
+	struct resolv_response *r_res;
+	struct eb32_node *eb32;
+	uint32_t key = 0;
+	int i, found = 0;
+	int cause = RSLV_RESP_ERROR;
+
+	reader         = resp;
+	len            = 0;
+	previous_dname = NULL;
+	query      = NULL;
+	answer_record = NULL;
+
+	/* Initialization of response buffer and structure */
+	r_res = &resolution->response;
+
+	/* query id */
+	if (reader + 2 >= bufend)
+		goto invalid_resp;
+
+	r_res->header.id = reader[0] * 256 + reader[1];
+	reader += 2;
+
+	/* Flags and rcode are stored over 2 bytes
+	 * First byte contains:
+	 *  - response flag (1 bit)
+	 *  - opcode (4 bits)
+	 *  - authoritative (1 bit)
+	 *  - truncated (1 bit)
+	 *  - recursion desired (1 bit)
+	 */
+	if (reader + 2 >= bufend)
+		goto invalid_resp;
+
+	flags = reader[0] * 256 + reader[1];
+
+	if ((flags & DNS_FLAG_REPLYCODE) != DNS_RCODE_NO_ERROR) {
+		if ((flags & DNS_FLAG_REPLYCODE) == DNS_RCODE_NX_DOMAIN) {
+			cause = RSLV_RESP_NX_DOMAIN;
+			goto return_error;
+		}
+		else if ((flags & DNS_FLAG_REPLYCODE) == DNS_RCODE_REFUSED) {
+			cause = RSLV_RESP_REFUSED;
+			goto return_error;
+		}
+		else {
+			cause = RSLV_RESP_ERROR;
+			goto return_error;
+		}
+	}
+
+	/* Move forward 2 bytes for flags */
+	reader += 2;
+
+	/* 2 bytes for question count */
+	if (reader + 2 >= bufend)
+		goto invalid_resp;
+	r_res->header.qdcount = reader[0] * 256 + reader[1];
+	/* (for now) we send one query only, so we expect only one in the
+	 * response too */
+	if (r_res->header.qdcount != 1) {
+		cause = RSLV_RESP_QUERY_COUNT_ERROR;
+		goto return_error;
+	}
+
+	if (r_res->header.qdcount > DNS_MAX_QUERY_RECORDS)
+		goto invalid_resp;
+	reader += 2;
+
+	/* 2 bytes for answer count */
+	if (reader + 2 >= bufend)
+		goto invalid_resp;
+	r_res->header.ancount = reader[0] * 256 + reader[1];
+	if (r_res->header.ancount == 0) {
+		cause = RSLV_RESP_ANCOUNT_ZERO;
+		goto return_error;
+	}
+
+	/* Check if too many records are announced */
+	if (r_res->header.ancount > max_answer_records)
+		goto invalid_resp;
+	reader += 2;
+
+	/* 2 bytes authority count */
+	if (reader + 2 >= bufend)
+		goto invalid_resp;
+	r_res->header.nscount = reader[0] * 256 + reader[1];
+	reader += 2;
+
+	/* 2 bytes additional count */
+	if (reader + 2 >= bufend)
+		goto invalid_resp;
+	r_res->header.arcount = reader[0] * 256 + reader[1];
+	reader += 2;
+
+	/* Parsing dns queries. For now there is only one query and it exists
+	 * because (qdcount == 1).
+	 */
+	query = &resolution->response_query_records[0];
+
+	/* Name is a NULL terminated string in our case, since we have
+	 * one query per response and the first one can't be compressed
+	 * (using the 0x0c format) */
+	offset = 0;
+	len = resolv_read_name(resp, bufend, reader, query->name, DNS_MAX_NAME_SIZE, &offset, 0);
+
+	if (len == 0)
+		goto invalid_resp;
+
+	/* Now let's check the query's dname corresponds to the one we sent. */
+	if (len != resolution->hostname_dn_len ||
+	    memcmp(query->name, resolution->hostname_dn, resolution->hostname_dn_len) != 0) {
+		cause = RSLV_RESP_WRONG_NAME;
+		goto return_error;
+	}
+
+	reader += offset;
+	previous_dname = query->name;
+
+	/* move forward 2 bytes for question type */
+	if (reader + 2 >= bufend)
+		goto invalid_resp;
+	query->type = reader[0] * 256 + reader[1];
+	reader += 2;
+
+	/* move forward 2 bytes for question class */
+	if (reader + 2 >= bufend)
+		goto invalid_resp;
+	query->class = reader[0] * 256 + reader[1];
+	reader += 2;
+
+	/* TRUNCATED flag must be checked after we could read the query type
+	 * because a TRUNCATED SRV query type response can still be exploited
+	 */
+	if (query->type != DNS_RTYPE_SRV && flags & DNS_FLAG_TRUNCATED) {
+		cause = RSLV_RESP_TRUNCATED;
+		goto return_error;
+	}
+
+	/* now parsing response records */
+	nb_saved_records = 0;
+	for (i = 0; i < r_res->header.ancount; i++) {
+		if (reader >= bufend)
+			goto invalid_resp;
+
+		answer_record = pool_alloc(resolv_answer_item_pool);
+		if (answer_record == NULL)
+			goto invalid_resp;
+
+		/* initialization */
+		answer_record->ar_item = NULL;
+		answer_record->last_seen = TICK_ETERNITY;
+		LIST_INIT(&answer_record->attached_servers);
+		answer_record->link.node.leaf_p = NULL;
+
+		offset = 0;
+		len = resolv_read_name(resp, bufend, reader, tmpname, DNS_MAX_NAME_SIZE, &offset, 0);
+
+		if (len == 0)
+			goto invalid_resp;
+
+		/* Check if the current record dname is valid.  previous_dname
+		 * points either to queried dname or last CNAME target */
+		if (query->type != DNS_RTYPE_SRV && memcmp(previous_dname, tmpname, len) != 0) {
+			if (i == 0) {
+				/* First record, means a mismatch issue between
+				 * queried dname and dname found in the first
+				 * record */
+				goto invalid_resp;
+			}
+			else {
+				/* If not the first record, this means we have a
+				 * CNAME resolution error.
+				 */
+				cause = RSLV_RESP_CNAME_ERROR;
+				goto return_error;
+			}
+
+		}
+
+		memcpy(answer_record->name, tmpname, len);
+		answer_record->name[len] = 0;
+
+		reader += offset;
+		if (reader >= bufend)
+			goto invalid_resp;
+
+		/* 2 bytes for record type (A, AAAA, CNAME, etc...) */
+		if (reader + 2 > bufend)
+			goto invalid_resp;
+
+		answer_record->type = reader[0] * 256 + reader[1];
+		reader += 2;
+
+		/* 2 bytes for class (2) */
+		if (reader + 2 > bufend)
+			goto invalid_resp;
+
+		answer_record->class = reader[0] * 256 + reader[1];
+		reader += 2;
+
+		/* 4 bytes for ttl (4) */
+		if (reader + 4 > bufend)
+			goto invalid_resp;
+
+		answer_record->ttl =   reader[0] * 16777216 + reader[1] * 65536
+		                     + reader[2] * 256 + reader[3];
+		reader += 4;
+
+		/* Now reading data len */
+		if (reader + 2 > bufend)
+			goto invalid_resp;
+
+		answer_record->data_len = reader[0] * 256 + reader[1];
+
+		/* Move forward 2 bytes for data len */
+		reader += 2;
+
+		if (reader + answer_record->data_len > bufend)
+			goto invalid_resp;
+
+		/* Analyzing record content */
+		switch (answer_record->type) {
+			case DNS_RTYPE_A:
+				/* ipv4 is stored on 4 bytes */
+				if (answer_record->data_len != 4)
+					goto invalid_resp;
+
+				answer_record->data.in4.sin_family = AF_INET;
+				memcpy(&answer_record->data.in4.sin_addr, reader, answer_record->data_len);
+				key = XXH32(reader, answer_record->data_len, answer_record->type);
+				break;
+
+			case DNS_RTYPE_CNAME:
+				/* Check if this is the last record and update the caller about the status:
+				 * no IP could be found and last record was a CNAME. Could be triggered
+				 * by a wrong query type
+				 *
+				 * + 1 because answer_record_id starts at 0
+				 * while number of answers is an integer and
+				 * starts at 1.
+				 */
+				if (i + 1 == r_res->header.ancount) {
+					cause = RSLV_RESP_CNAME_ERROR;
+					goto return_error;
+				}
+
+				offset = 0;
+				len = resolv_read_name(resp, bufend, reader, tmpname, DNS_MAX_NAME_SIZE, &offset, 0);
+				if (len == 0)
+					goto invalid_resp;
+
+				memcpy(answer_record->data.target, tmpname, len);
+				answer_record->data.target[len] = 0;
+				key = XXH32(tmpname, len, answer_record->type);
+				previous_dname = answer_record->data.target;
+				break;
+
+
+			case DNS_RTYPE_SRV:
+				/* Answer must contain :
+				 * - 2 bytes for the priority
+				 * - 2 bytes for the weight
+				 * - 2 bytes for the port
+				 * - the target hostname
+				 */
+				if (answer_record->data_len <= 6)
+					goto invalid_resp;
+
+				answer_record->priority = read_n16(reader);
+				reader += sizeof(uint16_t);
+				answer_record->weight = read_n16(reader);
+				reader += sizeof(uint16_t);
+				answer_record->port = read_n16(reader);
+				reader += sizeof(uint16_t);
+				offset = 0;
+				len = resolv_read_name(resp, bufend, reader, tmpname, DNS_MAX_NAME_SIZE, &offset, 0);
+				if (len == 0)
+					goto invalid_resp;
+
+				answer_record->data_len = len;
+				memcpy(answer_record->data.target, tmpname, len);
+				answer_record->data.target[len] = 0;
+				key = XXH32(tmpname, len, answer_record->type);
+				if (answer_record->ar_item != NULL) {
+					pool_free(resolv_answer_item_pool, answer_record->ar_item);
+					answer_record->ar_item = NULL;
+				}
+				break;
+
+			case DNS_RTYPE_AAAA:
+				/* ipv6 is stored on 16 bytes */
+				if (answer_record->data_len != 16)
+					goto invalid_resp;
+
+				answer_record->data.in6.sin6_family = AF_INET6;
+				memcpy(&answer_record->data.in6.sin6_addr, reader, answer_record->data_len);
+				key = XXH32(reader, answer_record->data_len, answer_record->type);
+				break;
+
+		} /* switch (record type) */
+
+		/* Increment the counter for number of records saved into our
+		 * local response */
+		nb_saved_records++;
+
+		/* Move forward answer_record->data_len for analyzing next
+		 * record in the response */
+		reader += ((answer_record->type == DNS_RTYPE_SRV)
+			   ? offset
+			   : answer_record->data_len);
+
+		/* Lookup to see if we already had this entry */
+		found = 0;
+
+		for (eb32 = eb32_lookup(&r_res->answer_tree, key); eb32 != NULL;  eb32 = eb32_next(eb32)) {
+			tmp_record = eb32_entry(eb32, typeof(*tmp_record), link);
+			if (tmp_record->type != answer_record->type)
+				continue;
+
+			switch(tmp_record->type) {
+				case DNS_RTYPE_A:
+					if (!memcmp(&answer_record->data.in4.sin_addr,
+						    &tmp_record->data.in4.sin_addr,
+						    sizeof(answer_record->data.in4.sin_addr)))
+						found = 1;
+					break;
+
+				case DNS_RTYPE_AAAA:
+					if (!memcmp(&answer_record->data.in6.sin6_addr,
+						    &tmp_record->data.in6.sin6_addr,
+						    sizeof(answer_record->data.in6.sin6_addr)))
+						found = 1;
+					break;
+
+			case DNS_RTYPE_SRV:
+                                if (answer_record->data_len == tmp_record->data_len &&
+				    memcmp(answer_record->data.target, tmp_record->data.target, answer_record->data_len) == 0 &&
+				    answer_record->port == tmp_record->port) {
+					tmp_record->weight = answer_record->weight;
+                                        found = 1;
+				}
+                                break;
+
+			default:
+				break;
+			}
+
+			if (found == 1)
+				break;
+		}
+
+		if (found == 1) {
+			tmp_record->last_seen = now_ms;
+			pool_free(resolv_answer_item_pool, answer_record);
+			answer_record = NULL;
+		}
+		else {
+			answer_record->last_seen = now_ms;
+			answer_record->ar_item = NULL;
+			answer_record->link.key = key;
+			eb32_insert(&r_res->answer_tree, &answer_record->link);
+			answer_record = NULL;
+		}
+	} /* for i 0 to ancount */
+
+	/* Save the number of records we really own */
+	r_res->header.ancount = nb_saved_records;
+
+	/* now parsing additional records for SRV queries only */
+	if (query->type != DNS_RTYPE_SRV)
+		goto skip_parsing_additional_records;
+
+	/* if we find Authority records, just skip them */
+	for (i = 0; i < r_res->header.nscount; i++) {
+		offset = 0;
+		len = resolv_read_name(resp, bufend, reader, tmpname, DNS_MAX_NAME_SIZE,
+		                    &offset, 0);
+		if (len == 0)
+			continue;
+
+		if (reader + offset + 10 >= bufend)
+			goto invalid_resp;
+
+		reader += offset;
+		/* skip 2 bytes for class */
+		reader += 2;
+		/* skip 2 bytes for type */
+		reader += 2;
+		/* skip 4 bytes for ttl */
+		reader += 4;
+		/* read data len */
+		len = reader[0] * 256 + reader[1];
+		reader += 2;
+
+		if (reader + len >= bufend)
+			goto invalid_resp;
+
+		reader += len;
+	}
+
+	nb_saved_records = 0;
+	for (i = 0; i < r_res->header.arcount; i++) {
+		if (reader >= bufend)
+			goto invalid_resp;
+
+		answer_record = pool_alloc(resolv_answer_item_pool);
+		if (answer_record == NULL)
+			goto invalid_resp;
+		answer_record->last_seen = TICK_ETERNITY;
+		LIST_INIT(&answer_record->attached_servers);
+
+		offset = 0;
+		len = resolv_read_name(resp, bufend, reader, tmpname, DNS_MAX_NAME_SIZE, &offset, 0);
+
+		if (len == 0) {
+			pool_free(resolv_answer_item_pool, answer_record);
+			answer_record = NULL;
+			continue;
+		}
+
+		memcpy(answer_record->name, tmpname, len);
+		answer_record->name[len] = 0;
+
+		reader += offset;
+		if (reader >= bufend)
+			goto invalid_resp;
+
+		/* 2 bytes for record type (A, AAAA, CNAME, etc...) */
+		if (reader + 2 > bufend)
+			goto invalid_resp;
+
+		answer_record->type = reader[0] * 256 + reader[1];
+		reader += 2;
+
+		/* 2 bytes for class (2) */
+		if (reader + 2 > bufend)
+			goto invalid_resp;
+
+		answer_record->class = reader[0] * 256 + reader[1];
+		reader += 2;
+
+		/* 4 bytes for ttl (4) */
+		if (reader + 4 > bufend)
+			goto invalid_resp;
+
+		answer_record->ttl =   reader[0] * 16777216 + reader[1] * 65536
+		                     + reader[2] * 256 + reader[3];
+		reader += 4;
+
+		/* Now reading data len */
+		if (reader + 2 > bufend)
+			goto invalid_resp;
+
+		answer_record->data_len = reader[0] * 256 + reader[1];
+
+		/* Move forward 2 bytes for data len */
+		reader += 2;
+
+		if (reader + answer_record->data_len > bufend)
+			goto invalid_resp;
+
+		/* Analyzing record content */
+		switch (answer_record->type) {
+			case DNS_RTYPE_A:
+				/* ipv4 is stored on 4 bytes */
+				if (answer_record->data_len != 4)
+					goto invalid_resp;
+
+				answer_record->data.in4.sin_family = AF_INET;
+				memcpy(&answer_record->data.in4.sin_addr, reader, answer_record->data_len);
+				break;
+
+			case DNS_RTYPE_AAAA:
+				/* ipv6 is stored on 16 bytes */
+				if (answer_record->data_len != 16)
+					goto invalid_resp;
+
+				answer_record->data.in6.sin6_family = AF_INET6;
+				memcpy(&answer_record->data.in6.sin6_addr, reader, answer_record->data_len);
+				break;
+
+			default:
+				pool_free(resolv_answer_item_pool, answer_record);
+				answer_record = NULL;
+				continue;
+
+		} /* switch (record type) */
+
+		/* Increment the counter for number of records saved into our
+		 * local response */
+		nb_saved_records++;
+
+		/* Move forward answer_record->data_len for analyzing next
+		 * record in the response */
+		reader += answer_record->data_len;
+
+		/* Lookup to see if we already had this entry */
+		found = 0;
+
+		for (eb32 = eb32_first(&r_res->answer_tree); eb32 != NULL;  eb32 = eb32_next(eb32)) {
+			struct resolv_answer_item *ar_item;
+
+			tmp_record = eb32_entry(eb32, typeof(*tmp_record), link);
+			if (tmp_record->type != DNS_RTYPE_SRV || !tmp_record->ar_item)
+				continue;
+
+			ar_item = tmp_record->ar_item;
+			if (ar_item->type != answer_record->type || ar_item->last_seen == now_ms ||
+			    len != tmp_record->data_len ||
+			    memcmp(answer_record->name, tmp_record->data.target, tmp_record->data_len) != 0)
+				continue;
+
+			switch(ar_item->type) {
+				case DNS_RTYPE_A:
+					if (!memcmp(&answer_record->data.in4.sin_addr,
+						    &ar_item->data.in4.sin_addr,
+						    sizeof(answer_record->data.in4.sin_addr)))
+						found = 1;
+					break;
+
+				case DNS_RTYPE_AAAA:
+					if (!memcmp(&answer_record->data.in6.sin6_addr,
+						    &ar_item->data.in6.sin6_addr,
+						    sizeof(answer_record->data.in6.sin6_addr)))
+						found = 1;
+					break;
+
+				default:
+					break;
+			}
+
+			if (found == 1)
+				break;
+		}
+
+		if (found == 1) {
+			tmp_record->ar_item->last_seen = now_ms;
+			pool_free(resolv_answer_item_pool, answer_record);
+			answer_record = NULL;
+		}
+		else {
+			answer_record->last_seen = now_ms;
+			answer_record->ar_item = NULL;
+
+			// looking for the SRV record in the response list linked to this additional record
+			for (eb32 = eb32_first(&r_res->answer_tree); eb32 != NULL;  eb32 = eb32_next(eb32)) {
+				tmp_record = eb32_entry(eb32, typeof(*tmp_record), link);
+
+				if (tmp_record->type == DNS_RTYPE_SRV &&
+				    tmp_record->ar_item == NULL &&
+				    memcmp(tmp_record->data.target, answer_record->name, tmp_record->data_len) == 0) {
+					/* Always use the received additional record to refresh info */
+					pool_free(resolv_answer_item_pool, tmp_record->ar_item);
+					tmp_record->ar_item = answer_record;
+					answer_record = NULL;
+					break;
+				}
+			}
+			if (answer_record) {
+				pool_free(resolv_answer_item_pool, answer_record);
+				answer_record = NULL;
+			}
+		}
+	} /* for i 0 to arcount */
+
+ skip_parsing_additional_records:
+
+	/* Save the number of records we really own */
+	r_res->header.arcount = nb_saved_records;
+	resolv_check_response(resolution);
+	return RSLV_RESP_VALID;
+
+ invalid_resp:
+	cause = RSLV_RESP_INVALID;
+
+ return_error:
+	pool_free(resolv_answer_item_pool, answer_record);
+	return cause;
+}
+
+/* Searches dn_name resolution in resp.
+ * If existing IP not found, return the first IP matching family_priority,
+ * otherwise, first ip found
+ * The following tasks are the responsibility of the caller:
+ *   - <r_res> contains an error free DNS response
+ * For both cases above, resolv_validate_dns_response is required
+ * returns one of the RSLV_UPD_* code
+ */
+int resolv_get_ip_from_response(struct resolv_response *r_res,
+                             struct resolv_options *resolv_opts, void *currentip,
+                             short currentip_sin_family,
+                             void **newip, short *newip_sin_family,
+                             struct server *owner)
+{
+	struct resolv_answer_item *record, *found_record = NULL;
+	struct eb32_node *eb32;
+	int family_priority;
+	int currentip_found;
+	unsigned char *newip4, *newip6;
+	int currentip_sel;
+	int j;
+	int score, max_score;
+	int allowed_duplicated_ip;
+
+	/* srv is linked to an alive ip record */
+	if (owner && LIST_INLIST(&owner->ip_rec_item))
+		return RSLV_UPD_NO;
+
+	family_priority   = resolv_opts->family_prio;
+	allowed_duplicated_ip = resolv_opts->accept_duplicate_ip;
+	*newip = newip4   = newip6 = NULL;
+	currentip_found   = 0;
+	*newip_sin_family = AF_UNSPEC;
+	max_score         = -1;
+
+	/* Select an IP regarding configuration preference.
+	 * Top priority is the preferred network ip version,
+	 * second priority is the preferred network.
+	 * the last priority is the currently used IP,
+	 *
+	 * For these three priorities, a score is calculated. The
+	 * weight are:
+	 *  8 - preferred ip version.
+	 *  4 - preferred network.
+	 *  2 - if the ip in the record is not affected to any other server in the same backend (duplication)
+	 *  1 - current ip.
+	 * The result with the biggest score is returned.
+	 */
+
+	for (eb32 = eb32_first(&r_res->answer_tree); eb32 != NULL;  eb32 = eb32_next(eb32)) {
+		void *ip;
+		unsigned char ip_type;
+
+		record = eb32_entry(eb32, typeof(*record), link);
+		if (record->type == DNS_RTYPE_A) {
+			ip_type = AF_INET;
+			ip = &record->data.in4.sin_addr;
+		}
+		else if (record->type == DNS_RTYPE_AAAA) {
+			ip_type = AF_INET6;
+			ip = &record->data.in6.sin6_addr;
+		}
+		else
+			continue;
+		score = 0;
+
+		/* Check for preferred ip protocol. */
+		if (ip_type == family_priority)
+			score += 8;
+
+		/* Check for preferred network. */
+		for (j = 0; j < resolv_opts->pref_net_nb; j++) {
+
+			/* Compare only the same addresses class. */
+			if (resolv_opts->pref_net[j].family != ip_type)
+				continue;
+
+			if ((ip_type == AF_INET &&
+			     in_net_ipv4(ip,
+			                 &resolv_opts->pref_net[j].mask.in4,
+			                 &resolv_opts->pref_net[j].addr.in4)) ||
+			    (ip_type == AF_INET6 &&
+			     in_net_ipv6(ip,
+			                 &resolv_opts->pref_net[j].mask.in6,
+			                 &resolv_opts->pref_net[j].addr.in6))) {
+				score += 4;
+				break;
+			}
+		}
+
+		/* Check if the IP found in the record is already affected to a
+		 * member of a group.  If not, the score should be incremented
+		 * by 2. */
+		if (owner) {
+			struct server *srv;
+			int already_used = 0;
+
+			list_for_each_entry(srv, &record->attached_servers, ip_rec_item) {
+				if (srv == owner)
+					continue;
+				if (srv->proxy == owner->proxy) {
+					already_used = 1;
+					break;
+				}
+			}
+			if (already_used) {
+				if (!allowed_duplicated_ip) {
+					continue;
+				}
+			}
+			else {
+				score += 2;
+			}
+		} else {
+			score += 2;
+		}
+
+		/* Check for current ip matching. */
+		if (ip_type == currentip_sin_family &&
+		    ((currentip_sin_family == AF_INET &&
+		      !memcmp(ip, currentip, 4)) ||
+		     (currentip_sin_family == AF_INET6 &&
+		      !memcmp(ip, currentip, 16)))) {
+			score++;
+			currentip_sel = 1;
+		}
+		else
+			currentip_sel = 0;
+
+		/* Keep the address if the score is better than the previous
+		 * score. The maximum score is 15, if this value is reached, we
+		 * break the parsing. Implicitly, this score is reached the ip
+		 * selected is the current ip. */
+		if (score > max_score) {
+			if (ip_type == AF_INET)
+				newip4 = ip;
+			else
+				newip6 = ip;
+			found_record = record;
+			currentip_found = currentip_sel;
+			if (score == 15) {
+				/* this was not registered on the current record but it matches
+				 * let's fix it (it may comes from state file */
+				if (owner)
+					LIST_APPEND(&found_record->attached_servers, &owner->ip_rec_item);
+				return RSLV_UPD_NO;
+			}
+			max_score = score;
+		}
+	} /* list for each record entries */
+
+	/* No IP found in the response */
+	if (!newip4 && !newip6)
+		return RSLV_UPD_NO_IP_FOUND;
+
+	/* Case when the caller looks first for an IPv4 address */
+	if (family_priority == AF_INET) {
+		if (newip4) {
+			*newip = newip4;
+			*newip_sin_family = AF_INET;
+		}
+		else if (newip6) {
+			*newip = newip6;
+			*newip_sin_family = AF_INET6;
+		}
+	}
+	/* Case when the caller looks first for an IPv6 address */
+	else if (family_priority == AF_INET6) {
+		if (newip6) {
+			*newip = newip6;
+			*newip_sin_family = AF_INET6;
+		}
+		else if (newip4) {
+			*newip = newip4;
+			*newip_sin_family = AF_INET;
+		}
+	}
+	/* Case when the caller have no preference (we prefer IPv6) */
+	else if (family_priority == AF_UNSPEC) {
+		if (newip6) {
+			*newip = newip6;
+			*newip_sin_family = AF_INET6;
+		}
+		else if (newip4) {
+			*newip = newip4;
+			*newip_sin_family = AF_INET;
+		}
+	}
+
+	/* the ip of this record was chosen for the server */
+	if (owner && found_record) {
+		LIST_DEL_INIT(&owner->ip_rec_item);
+		LIST_APPEND(&found_record->attached_servers, &owner->ip_rec_item);
+	}
+
+	eb32 = eb32_first(&r_res->answer_tree);
+	if (eb32) {
+		/* Move the first record to the end of the list, for internal
+		 * round robin.
+		 */
+		eb32_delete(eb32);
+		eb32_insert(&r_res->answer_tree, eb32);
+	}
+
+	return (currentip_found ? RSLV_UPD_NO : RSLV_UPD_SRVIP_NOT_FOUND);
+}
+
+/* Turns a domain name label into a string: 3www7haproxy3org into www.haproxy.org
+ *
+ * <dn> contains the input label of <dn_len> bytes long and does not need to be
+ * null-terminated. <str> must be allocated large enough to contain a full host
+ * name plus the trailing zero, and the allocated size must be passed in
+ * <str_len>.
+ *
+ * In case of error, -1 is returned, otherwise, the number of bytes copied in
+ * <str> (including the terminating null byte).
+ */
+int resolv_dn_label_to_str(const char *dn, int dn_len, char *str, int str_len)
+{
+	char *ptr;
+	int i, sz;
+
+	if (str_len < dn_len)
+		return -1;
+
+	ptr = str;
+	for (i = 0; i < dn_len; ++i) {
+		sz = dn[i];
+		if (i)
+			*ptr++ = '.';
+		/* copy the string at i+1 to lower case */
+		for (; sz > 0; sz--)
+			*(ptr++) = tolower(dn[++i]);
+	}
+	*ptr++ = '\0';
+	return (ptr - str);
+}
+
+/* Turns a string into domain name label: www.haproxy.org into 3www7haproxy3org
+ *
+ * <str> contains the input string that is <str_len> bytes long (trailing zero
+ * not needed). <dn> buffer must be allocated large enough to contain the
+ * encoded string and a trailing zero, so it must be at least str_len+2, and
+ * this allocated buffer size must be passed in <dn_len>.
+ *
+ * In case of error, -1 is returned, otherwise, the number of bytes copied in
+ * <dn> (excluding the terminating null byte).
+ */
+int resolv_str_to_dn_label(const char *str, int str_len, char *dn, int dn_len)
+{
+	int i, offset;
+
+	if (dn_len < str_len + 2)
+		return -1;
+
+	/* First byte of dn will be used to store the length of the first
+	 * label */
+	offset = 0;
+	for (i = 0; i < str_len; ++i) {
+		if (str[i] == '.') {
+			/* 2 or more consecutive dots is invalid */
+			if (i == offset)
+				return -1;
+
+			/* ignore trailing dot */
+			if (i + 1 == str_len)
+				break;
+
+			dn[offset] = (i - offset);
+			offset = i+1;
+			continue;
+		}
+		dn[i+1] = tolower(str[i]);
+	}
+	dn[offset] = i - offset;
+	dn[i+1] = '\0';
+	return i+1;
+}
+
+/* Validates host name:
+ *  - total size
+ *  - each label size individually
+ * returns:
+ *  0 in case of error. If <err> is not NULL, an error message is stored there.
+ *  1 when no error. <err> is left unaffected.
+ */
+int resolv_hostname_validation(const char *string, char **err)
+{
+	int i;
+
+	if (strlen(string) > DNS_MAX_NAME_SIZE) {
+		if (err)
+			*err = DNS_TOO_LONG_FQDN;
+		return 0;
+	}
+
+	while (*string) {
+		i = 0;
+		while (*string && *string != '.' && i < DNS_MAX_LABEL_SIZE) {
+			if (!(*string == '-' || *string == '_' ||
+			      (*string >= 'a' && *string <= 'z') ||
+			      (*string >= 'A' && *string <= 'Z') ||
+			      (*string >= '0' && *string <= '9'))) {
+				if (err)
+					*err = DNS_INVALID_CHARACTER;
+				return 0;
+			}
+			i++;
+			string++;
+		}
+
+		if (!(*string))
+			break;
+
+		if (*string != '.' && i >= DNS_MAX_LABEL_SIZE) {
+			if (err)
+				*err = DNS_LABEL_TOO_LONG;
+			return 0;
+		}
+
+		string++;
+	}
+	return 1;
+}
+
+/* Picks up an available resolution from the different resolution list
+ * associated to a resolvers section, in this order:
+ *   1. check in resolutions.curr for the same hostname and query_type
+ *   2. check in resolutions.wait for the same hostname and query_type
+ *   3. Get a new resolution from resolution pool
+ *
+ * Returns an available resolution, NULL if none found.
+ */
+static struct resolv_resolution *resolv_pick_resolution(struct resolvers *resolvers,
+							char **hostname_dn, int hostname_dn_len,
+							int query_type)
+{
+	struct resolv_resolution *res;
+
+	if (!*hostname_dn)
+		goto from_pool;
+
+	/* Search for same hostname and query type in resolutions.curr */
+	list_for_each_entry(res, &resolvers->resolutions.curr, list) {
+		if (!res->hostname_dn)
+			continue;
+		if ((query_type == res->prefered_query_type) &&
+		    hostname_dn_len == res->hostname_dn_len  &&
+		    memcmp(*hostname_dn, res->hostname_dn, hostname_dn_len) == 0)
+			return res;
+	}
+
+	/* Search for same hostname and query type in resolutions.wait */
+	list_for_each_entry(res, &resolvers->resolutions.wait, list) {
+		if (!res->hostname_dn)
+			continue;
+		if ((query_type == res->prefered_query_type) &&
+		    hostname_dn_len == res->hostname_dn_len  &&
+		    memcmp(*hostname_dn, res->hostname_dn, hostname_dn_len) == 0)
+			return res;
+	}
+
+  from_pool:
+	/* No resolution could be found, so let's allocate a new one */
+	res = pool_zalloc(resolv_resolution_pool);
+	if (res) {
+		res->resolvers  = resolvers;
+		res->uuid       = resolution_uuid;
+		res->status     = RSLV_STATUS_NONE;
+		res->step       = RSLV_STEP_NONE;
+		res->last_valid = now_ms;
+
+		LIST_INIT(&res->requesters);
+		res->response.answer_tree = EB_ROOT;
+
+		res->prefered_query_type = query_type;
+		res->query_type          = query_type;
+		res->hostname_dn         = *hostname_dn;
+		res->hostname_dn_len     = hostname_dn_len;
+
+		++resolution_uuid;
+
+		/* Move the resolution to the resolvers wait queue */
+		LIST_APPEND(&resolvers->resolutions.wait, &res->list);
+	}
+	return res;
+}
+
+/* deletes and frees all answer_items from the resolution's answer_list */
+static void resolv_purge_resolution_answer_records(struct resolv_resolution *resolution)
+{
+	struct eb32_node *eb32, *eb32_back;
+	struct resolv_answer_item *item;
+
+	for (eb32 = eb32_first(&resolution->response.answer_tree);
+	     eb32 && (eb32_back = eb32_next(eb32), 1);
+	     eb32 = eb32_back) {
+		item = eb32_entry(eb32, typeof(*item), link);
+		eb32_delete(&item->link);
+		pool_free(resolv_answer_item_pool, item->ar_item);
+		pool_free(resolv_answer_item_pool, item);
+	}
+}
+
+/* Releases a resolution from its requester(s) and move it back to the pool */
+static void resolv_free_resolution(struct resolv_resolution *resolution)
+{
+	struct resolv_requester *req, *reqback;
+
+	/* clean up configuration */
+	resolv_reset_resolution(resolution);
+	resolution->hostname_dn = NULL;
+	resolution->hostname_dn_len = 0;
+
+	list_for_each_entry_safe(req, reqback, &resolution->requesters, list) {
+		LIST_DEL_INIT(&req->list);
+		req->resolution = NULL;
+	}
+	resolv_purge_resolution_answer_records(resolution);
+
+	LIST_DEL_INIT(&resolution->list);
+	pool_free(resolv_resolution_pool, resolution);
+}
+
+/* If *<req> is not NULL, returns it, otherwise tries to allocate a requester
+ * and makes it owned by this obj_type, with the proposed callback and error
+ * callback. On success, *req is assigned the allocated requester. Returns
+ * NULL on allocation failure.
+ */
+static struct resolv_requester *
+resolv_get_requester(struct resolv_requester **req, enum obj_type *owner,
+                     int (*cb)(struct resolv_requester *, struct dns_counters *),
+                     int (*err_cb)(struct resolv_requester *, int))
+{
+	struct resolv_requester *tmp;
+
+	if (*req)
+		return *req;
+
+	tmp = pool_alloc(resolv_requester_pool);
+	if (!tmp)
+		goto end;
+
+	LIST_INIT(&tmp->list);
+	tmp->owner              = owner;
+	tmp->resolution         = NULL;
+	tmp->requester_cb       = cb;
+	tmp->requester_error_cb = err_cb;
+	*req = tmp;
+ end:
+	return tmp;
+}
+
+/* Links a requester (a server or a resolv_srvrq) with a resolution. It returns 0
+ * on success, -1 otherwise.
+ */
+int resolv_link_resolution(void *requester, int requester_type, int requester_locked)
+{
+	struct resolv_resolution *res = NULL;
+	struct resolv_requester  *req;
+	struct resolvers  *resolvers;
+	struct server         *srv   = NULL;
+	struct resolv_srvrq      *srvrq = NULL;
+	struct stream         *stream = NULL;
+	char **hostname_dn;
+	int   hostname_dn_len, query_type;
+
+	enter_resolver_code();
+	switch (requester_type) {
+		case OBJ_TYPE_SERVER:
+			srv             = (struct server *)requester;
+
+			if (!requester_locked)
+				HA_SPIN_LOCK(SERVER_LOCK, &srv->lock);
+
+			req = resolv_get_requester(&srv->resolv_requester,
+			                           &srv->obj_type,
+				                   snr_resolution_cb,
+				                   snr_resolution_error_cb);
+
+			if (!requester_locked)
+				HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
+
+			if (!req)
+				goto err;
+
+			hostname_dn     = &srv->hostname_dn;
+			hostname_dn_len = srv->hostname_dn_len;
+			resolvers       = srv->resolvers;
+			query_type      = ((srv->resolv_opts.family_prio == AF_INET)
+					   ? DNS_RTYPE_A
+					   : DNS_RTYPE_AAAA);
+			break;
+
+		case OBJ_TYPE_SRVRQ:
+			srvrq           = (struct resolv_srvrq *)requester;
+
+			req = resolv_get_requester(&srvrq->requester,
+			                           &srvrq->obj_type,
+			                           snr_resolution_cb,
+			                           srvrq_resolution_error_cb);
+			if (!req)
+				goto err;
+
+			hostname_dn     = &srvrq->hostname_dn;
+			hostname_dn_len = srvrq->hostname_dn_len;
+			resolvers       = srvrq->resolvers;
+			query_type      = DNS_RTYPE_SRV;
+			break;
+
+		case OBJ_TYPE_STREAM:
+			stream          = (struct stream *)requester;
+
+			req = resolv_get_requester(&stream->resolv_ctx.requester,
+			                           &stream->obj_type,
+			                           act_resolution_cb,
+			                           act_resolution_error_cb);
+			if (!req)
+				goto err;
+
+			hostname_dn     = &stream->resolv_ctx.hostname_dn;
+			hostname_dn_len = stream->resolv_ctx.hostname_dn_len;
+			resolvers       = stream->resolv_ctx.parent->arg.resolv.resolvers;
+			query_type      = ((stream->resolv_ctx.parent->arg.resolv.opts->family_prio == AF_INET)
+					   ? DNS_RTYPE_A
+					   : DNS_RTYPE_AAAA);
+			break;
+		default:
+			goto err;
+	}
+
+	/* Get a resolution from the resolvers' wait queue or pool */
+	if ((res = resolv_pick_resolution(resolvers, hostname_dn, hostname_dn_len, query_type)) == NULL)
+		goto err;
+
+	req->resolution = res;
+
+	LIST_APPEND(&res->requesters, &req->list);
+	leave_resolver_code();
+	return 0;
+
+  err:
+	if (res && LIST_ISEMPTY(&res->requesters))
+		resolv_free_resolution(res);
+	leave_resolver_code();
+	return -1;
+}
+
+/* This function removes all server/srvrq references on answer items. */
+void resolv_detach_from_resolution_answer_items(struct resolv_resolution *res,  struct resolv_requester *req)
+{
+	struct eb32_node *eb32, *eb32_back;
+	struct resolv_answer_item *item;
+	struct server *srv, *srvback;
+	struct resolv_srvrq    *srvrq;
+
+	enter_resolver_code();
+	if ((srv = objt_server(req->owner)) != NULL) {
+		LIST_DEL_INIT(&srv->ip_rec_item);
+	}
+	else if ((srvrq = objt_resolv_srvrq(req->owner)) != NULL) {
+		for (eb32 = eb32_first(&res->response.answer_tree);
+		     eb32 && (eb32_back = eb32_next(eb32), 1);
+		     eb32 = eb32_back) {
+			item = eb32_entry(eb32, typeof(*item), link);
+			if (item->type == DNS_RTYPE_SRV) {
+				list_for_each_entry_safe(srv, srvback, &item->attached_servers, srv_rec_item) {
+					if (srv->srvrq == srvrq)
+						resolv_srvrq_cleanup_srv(srv);
+				}
+			}
+		}
+	}
+	leave_resolver_code();
+}
+
+/* Removes a requester from a DNS resolution. It takes takes care of all the
+ * consequences. It also cleans up some parameters from the requester.
+ */
+static void _resolv_unlink_resolution(struct resolv_requester *requester)
+{
+	struct resolv_resolution *res;
+	struct resolv_requester  *req;
+
+	/* Nothing to do */
+	if (!requester || !requester->resolution)
+		return;
+	res = requester->resolution;
+
+	/* Clean up the requester */
+	LIST_DEL_INIT(&requester->list);
+	requester->resolution = NULL;
+
+	/* remove ref from the resolution answer item list to the requester */
+	resolv_detach_from_resolution_answer_items(res,  requester);
+
+	/* We need to find another requester linked on this resolution */
+	if (!LIST_ISEMPTY(&res->requesters))
+		req = LIST_NEXT(&res->requesters, struct resolv_requester *, list);
+	else {
+		abort_resolution(res);
+		return;
+	}
+
+	/* Move hostname_dn related pointers to the next requester */
+	switch (obj_type(req->owner)) {
+		case OBJ_TYPE_SERVER:
+			res->hostname_dn     = __objt_server(req->owner)->hostname_dn;
+			res->hostname_dn_len = __objt_server(req->owner)->hostname_dn_len;
+			break;
+		case OBJ_TYPE_SRVRQ:
+			res->hostname_dn     = __objt_resolv_srvrq(req->owner)->hostname_dn;
+			res->hostname_dn_len = __objt_resolv_srvrq(req->owner)->hostname_dn_len;
+			break;
+		case OBJ_TYPE_STREAM:
+			res->hostname_dn     = __objt_stream(req->owner)->resolv_ctx.hostname_dn;
+			res->hostname_dn_len = __objt_stream(req->owner)->resolv_ctx.hostname_dn_len;
+			break;
+		default:
+			res->hostname_dn     = NULL;
+			res->hostname_dn_len = 0;
+			break;
+	}
+}
+
+/* The public version of the function above that deals with the death row. */
+void resolv_unlink_resolution(struct resolv_requester *requester)
+{
+	enter_resolver_code();
+	_resolv_unlink_resolution(requester);
+	leave_resolver_code();
+}
+
+/* Called when a network IO is generated on a name server socket for an incoming
+ * packet. It performs the following actions:
+ *  - check if the packet requires processing (not outdated resolution)
+ *  - ensure the DNS packet received is valid and call requester's callback
+ *  - call requester's error callback if invalid response
+ *  - check the dn_name in the packet against the one sent
+ */
+static int resolv_process_responses(struct dns_nameserver *ns)
+{
+	struct dns_counters   *tmpcounters;
+	struct resolvers  *resolvers;
+	struct resolv_resolution *res;
+	unsigned char  buf[DNS_MAX_UDP_MESSAGE + 1];
+	unsigned char *bufend;
+	int buflen, dns_resp;
+	int max_answer_records;
+	unsigned short query_id;
+	struct eb32_node *eb;
+	struct resolv_requester *req;
+	int keep_answer_items;
+
+	resolvers = ns->parent;
+	enter_resolver_code();
+	HA_SPIN_LOCK(DNS_LOCK, &resolvers->lock);
+
+	/* process all pending input messages */
+	while (1) {
+		/* read message received */
+		memset(buf, '\0', resolvers->accepted_payload_size + 1);
+		if ((buflen = dns_recv_nameserver(ns, (void *)buf, sizeof(buf))) <= 0) {
+			break;
+		}
+
+		/* message too big */
+		if (buflen > resolvers->accepted_payload_size) {
+			ns->counters->app.resolver.too_big++;
+			continue;
+		}
+
+		/* initializing variables */
+		bufend = buf + buflen;	/* pointer to mark the end of the buffer */
+
+		/* read the query id from the packet (16 bits) */
+		if (buf + 2 > bufend) {
+			ns->counters->app.resolver.invalid++;
+			continue;
+		}
+		query_id = resolv_response_get_query_id(buf);
+
+		/* search the query_id in the pending resolution tree */
+		eb = eb32_lookup(&resolvers->query_ids, query_id);
+		if (eb == NULL) {
+			/* unknown query id means an outdated response and can be safely ignored */
+			ns->counters->app.resolver.outdated++;
+			continue;
+		}
+
+		/* known query id means a resolution in progress */
+		res = eb32_entry(eb, struct resolv_resolution, qid);
+		/* number of responses received */
+		res->nb_responses++;
+
+		max_answer_records = (resolvers->accepted_payload_size - DNS_HEADER_SIZE) / DNS_MIN_RECORD_SIZE;
+		dns_resp = resolv_validate_dns_response(buf, bufend, res, max_answer_records);
+
+		switch (dns_resp) {
+			case RSLV_RESP_VALID:
+				break;
+
+			case RSLV_RESP_INVALID:
+			case RSLV_RESP_QUERY_COUNT_ERROR:
+			case RSLV_RESP_WRONG_NAME:
+				res->status = RSLV_STATUS_INVALID;
+				ns->counters->app.resolver.invalid++;
+				break;
+
+			case RSLV_RESP_NX_DOMAIN:
+				res->status = RSLV_STATUS_NX;
+				ns->counters->app.resolver.nx++;
+				break;
+
+			case RSLV_RESP_REFUSED:
+				res->status = RSLV_STATUS_REFUSED;
+				ns->counters->app.resolver.refused++;
+				break;
+
+			case RSLV_RESP_ANCOUNT_ZERO:
+				res->status = RSLV_STATUS_OTHER;
+				ns->counters->app.resolver.any_err++;
+				break;
+
+			case RSLV_RESP_CNAME_ERROR:
+				res->status = RSLV_STATUS_OTHER;
+				ns->counters->app.resolver.cname_error++;
+				break;
+
+			case RSLV_RESP_TRUNCATED:
+				res->status = RSLV_STATUS_OTHER;
+				ns->counters->app.resolver.truncated++;
+				break;
+
+			case RSLV_RESP_NO_EXPECTED_RECORD:
+			case RSLV_RESP_ERROR:
+			case RSLV_RESP_INTERNAL:
+				res->status = RSLV_STATUS_OTHER;
+				ns->counters->app.resolver.other++;
+				break;
+		}
+
+		/* Wait all nameservers response to handle errors */
+		if (dns_resp != RSLV_RESP_VALID && res->nb_responses < res->nb_queries)
+			continue;
+
+		/* Process error codes */
+		if (dns_resp != RSLV_RESP_VALID)  {
+			if (res->prefered_query_type != res->query_type) {
+				/* The fallback on the query type was already performed,
+				 * so check the try counter. If it falls to 0, we can
+				 * report an error. Else, wait the next attempt. */
+				if (!res->try)
+					goto report_res_error;
+			}
+			else {
+				/* Fallback from A to AAAA or the opposite and re-send
+				 * the resolution immediately. try counter is not
+				 * decremented. */
+				if (res->prefered_query_type == DNS_RTYPE_A) {
+					res->query_type = DNS_RTYPE_AAAA;
+					resolv_send_query(res);
+				}
+				else if (res->prefered_query_type == DNS_RTYPE_AAAA) {
+					res->query_type = DNS_RTYPE_A;
+					resolv_send_query(res);
+				}
+			}
+			continue;
+		}
+
+		/* So the resolution succeeded */
+		res->status     = RSLV_STATUS_VALID;
+		res->last_valid = now_ms;
+		ns->counters->app.resolver.valid++;
+		goto report_res_success;
+
+	report_res_error:
+		keep_answer_items = 0;
+		list_for_each_entry(req, &res->requesters, list)
+			keep_answer_items |= req->requester_error_cb(req, dns_resp);
+		if (!keep_answer_items)
+			resolv_purge_resolution_answer_records(res);
+		resolv_reset_resolution(res);
+		LIST_DEL_INIT(&res->list);
+		LIST_APPEND(&resolvers->resolutions.wait, &res->list);
+		continue;
+
+	report_res_success:
+		/* Only the 1rst requester s managed by the server, others are
+		 * from the cache */
+		tmpcounters = ns->counters;
+		list_for_each_entry(req, &res->requesters, list) {
+			struct server *s = objt_server(req->owner);
+
+			if (s)
+				HA_SPIN_LOCK(SERVER_LOCK, &s->lock);
+			req->requester_cb(req, tmpcounters);
+			if (s)
+				HA_SPIN_UNLOCK(SERVER_LOCK, &s->lock);
+			tmpcounters = NULL;
+		}
+
+		resolv_reset_resolution(res);
+		LIST_DEL_INIT(&res->list);
+		LIST_APPEND(&resolvers->resolutions.wait, &res->list);
+		continue;
+	}
+	resolv_update_resolvers_timeout(resolvers);
+	HA_SPIN_UNLOCK(DNS_LOCK, &resolvers->lock);
+	leave_resolver_code();
+	return buflen;
+}
+
+/* Processes DNS resolution. First, it checks the active list to detect expired
+ * resolutions and retry them if possible. Else a timeout is reported. Then, it
+ * checks the wait list to trigger new resolutions.
+ */
+struct task *process_resolvers(struct task *t, void *context, unsigned int state)
+{
+	struct resolvers  *resolvers = context;
+	struct resolv_resolution *res, *resback;
+	int exp;
+
+	enter_resolver_code();
+	HA_SPIN_LOCK(DNS_LOCK, &resolvers->lock);
+
+	/* Handle all expired resolutions from the active list. Elements that
+	 * need to be removed will in fact be moved to the death_row. Other
+	 * ones will be handled normally.
+	 */
+
+	res  = LIST_NEXT(&resolvers->resolutions.curr, struct resolv_resolution *, list);
+	while (&res->list != &resolvers->resolutions.curr) {
+		resback = LIST_NEXT(&res->list, struct resolv_resolution *, list);
+
+		if (LIST_ISEMPTY(&res->requesters)) {
+			abort_resolution(res);
+			res = resback;
+			continue;
+		}
+
+		/* When we find the first resolution in the future, then we can
+		 * stop here */
+		exp = tick_add(res->last_query, resolvers->timeout.retry);
+		if (!tick_is_expired(exp, now_ms))
+			break;
+
+		/* If current resolution has been tried too many times and
+		 * finishes in timeout we update its status and remove it from
+		 * the list */
+		if (!res->try) {
+			struct resolv_requester *req;
+			int keep_answer_items = 0;
+
+			/* Notify the result to the requesters */
+			if (!res->nb_responses)
+				res->status = RSLV_STATUS_TIMEOUT;
+			list_for_each_entry(req, &res->requesters, list)
+				keep_answer_items |= req->requester_error_cb(req, res->status);
+			if (!keep_answer_items)
+				resolv_purge_resolution_answer_records(res);
+
+			/* Clean up resolution info and remove it from the
+			 * current list */
+			resolv_reset_resolution(res);
+
+			/* subsequent entries might have been deleted here */
+			resback = LIST_NEXT(&res->list, struct resolv_resolution *, list);
+			LIST_DEL_INIT(&res->list);
+			LIST_APPEND(&resolvers->resolutions.wait, &res->list);
+			res = resback;
+		}
+		else {
+			/* Otherwise resend the DNS query and requeue the resolution */
+			if (!res->nb_responses || res->prefered_query_type != res->query_type) {
+				/* No response received (a real timeout) or fallback already done */
+				res->query_type = res->prefered_query_type;
+				res->try--;
+			}
+			else {
+				/* Fallback from A to AAAA or the opposite and re-send
+				 * the resolution immediately. try counter is not
+				 * decremented. */
+				if (res->prefered_query_type == DNS_RTYPE_A)
+					res->query_type = DNS_RTYPE_AAAA;
+				else if (res->prefered_query_type == DNS_RTYPE_AAAA)
+					res->query_type = DNS_RTYPE_A;
+				else
+					res->try--;
+			}
+			resolv_send_query(res);
+			resback = LIST_NEXT(&res->list, struct resolv_resolution *, list);
+			res = resback;
+		}
+	}
+
+	/* Handle all resolutions in the wait list */
+	list_for_each_entry_safe(res, resback, &resolvers->resolutions.wait, list) {
+
+		if (unlikely(stopping)) {
+			/* If haproxy is stopping, check if the resolution to know if it must be run or not.
+			 * If at least a requester is a stream (because of a do-resolv action) or if there
+			 * is a requester attached to a running proxy, the resolution is performed.
+			 * Otherwise, it is skipped for now.
+			 */
+			struct resolv_requester *req;
+			int must_run = 0;
+
+			list_for_each_entry(req, &res->requesters, list) {
+				struct proxy *px = NULL;
+
+				switch (obj_type(req->owner)) {
+					case OBJ_TYPE_SERVER:
+						px = __objt_server(req->owner)->proxy;
+						break;
+					case OBJ_TYPE_SRVRQ:
+						px = __objt_resolv_srvrq(req->owner)->proxy;
+						break;
+					case OBJ_TYPE_STREAM:
+						/* Always perform the resolution */
+						must_run = 1;
+						break;
+					default:
+						break;
+				}
+				/* Perform the resolution if the proxy is not stopped or disabled */
+				if (px && !(px->flags & (PR_FL_DISABLED|PR_FL_STOPPED)))
+					must_run = 1;
+
+				if (must_run)
+					break;
+			}
+
+			if (!must_run) {
+				/* Skip the reolsution. reset it and wait for the next wakeup */
+				resolv_reset_resolution(res);
+				continue;
+			}
+		}
+
+		if (LIST_ISEMPTY(&res->requesters)) {
+			abort_resolution(res);
+			continue;
+		}
+
+		exp = tick_add(res->last_resolution, resolv_resolution_timeout(res));
+		if (tick_isset(res->last_resolution) && !tick_is_expired(exp, now_ms))
+			continue;
+
+		if (resolv_run_resolution(res) != 1) {
+			res->last_resolution = now_ms;
+			LIST_DEL_INIT(&res->list);
+			LIST_APPEND(&resolvers->resolutions.wait, &res->list);
+		}
+	}
+
+	resolv_update_resolvers_timeout(resolvers);
+	HA_SPIN_UNLOCK(DNS_LOCK, &resolvers->lock);
+
+	if (unlikely(stopping)) {
+		struct dns_nameserver *ns;
+
+		if (LIST_ISEMPTY(&resolvers->resolutions.curr))
+			t->expire = TICK_ETERNITY;
+
+		list_for_each_entry(ns, &resolvers->nameservers, list) {
+			if (ns->stream)
+				task_wakeup(ns->stream->task_idle, TASK_WOKEN_MSG);
+		}
+	}
+
+	/* now we can purge all queued deletions */
+	leave_resolver_code();
+	return t;
+}
+
+
+/* destroy a resolvers */
+static void resolvers_destroy(struct resolvers *resolvers)
+{
+	struct dns_nameserver *ns, *nsback;
+	struct resolv_resolution *res, *resback;
+	struct resolv_requester  *req, *reqback;
+
+	list_for_each_entry_safe(ns, nsback, &resolvers->nameservers, list) {
+		free(ns->id);
+		free((char *)ns->conf.file);
+		if (ns->dgram) {
+			if (ns->dgram->conn.t.sock.fd != -1) {
+				fd_delete(ns->dgram->conn.t.sock.fd);
+				close(ns->dgram->conn.t.sock.fd);
+			}
+			ring_free(ns->dgram->ring_req);
+			free(ns->dgram);
+		}
+		if (ns->stream) {
+			ring_free(ns->stream->ring_req);
+			task_destroy(ns->stream->task_req);
+			task_destroy(ns->stream->task_rsp);
+			free(ns->stream);
+		}
+		LIST_DEL_INIT(&ns->list);
+		EXTRA_COUNTERS_FREE(ns->extra_counters);
+		free(ns);
+	}
+
+	list_for_each_entry_safe(res, resback, &resolvers->resolutions.curr, list) {
+		list_for_each_entry_safe(req, reqback, &res->requesters, list) {
+			LIST_DEL_INIT(&req->list);
+			pool_free(resolv_requester_pool, req);
+		}
+		resolv_free_resolution(res);
+	}
+
+	list_for_each_entry_safe(res, resback, &resolvers->resolutions.wait, list) {
+		list_for_each_entry_safe(req, reqback, &res->requesters, list) {
+			LIST_DEL_INIT(&req->list);
+			pool_free(resolv_requester_pool, req);
+		}
+		resolv_free_resolution(res);
+	}
+
+	free_proxy(resolvers->px);
+	free(resolvers->id);
+	free((char *)resolvers->conf.file);
+	task_destroy(resolvers->t);
+	LIST_DEL_INIT(&resolvers->list);
+	free(resolvers);
+}
+
+/* Release memory allocated by DNS */
+static void resolvers_deinit(void)
+{
+	struct resolvers  *resolvers, *resolversback;
+	struct resolv_srvrq    *srvrq, *srvrqback;
+
+	list_for_each_entry_safe(resolvers, resolversback, &sec_resolvers, list) {
+		resolvers_destroy(resolvers);
+	}
+
+	list_for_each_entry_safe(srvrq, srvrqback, &resolv_srvrq_list, list) {
+		free(srvrq->name);
+		free(srvrq->hostname_dn);
+		LIST_DEL_INIT(&srvrq->list);
+		free(srvrq);
+	}
+}
+
+/* Finalizes the DNS configuration by allocating required resources and checking
+ * live parameters.
+ * Returns 0 on success, 1 on error.
+ */
+static int resolvers_finalize_config(void)
+{
+	struct resolvers *resolvers;
+	struct proxy	     *px;
+	int err_code = 0;
+
+	enter_resolver_code();
+
+	/* allocate pool of resolution per resolvers */
+	list_for_each_entry(resolvers, &sec_resolvers, list) {
+		struct dns_nameserver *ns;
+		struct task           *t;
+
+		/* Check if we can create the socket with nameservers info */
+		list_for_each_entry(ns, &resolvers->nameservers, list) {
+			int fd;
+
+			if (ns->dgram) {
+				/* Check nameserver info */
+				if ((fd = socket(ns->dgram->conn.addr.to.ss_family, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
+					if (!resolvers->conf.implicit) {  /* emit a warning only if it was configured manually */
+						ha_alert("resolvers '%s': can't create socket for nameserver '%s'.\n",
+							 resolvers->id, ns->id);
+						err_code |= (ERR_ALERT|ERR_ABORT);
+					}
+					continue;
+				}
+				if (connect(fd, (struct sockaddr*)&ns->dgram->conn.addr.to, get_addr_len(&ns->dgram->conn.addr.to)) == -1) {
+					if (!resolvers->conf.implicit) { /* emit a warning only if it was configured manually */
+						ha_warning("resolvers '%s': can't connect socket for nameserver '%s'.\n",
+						            resolvers->id, ns->id);
+					}
+					close(fd);
+					err_code |= ERR_WARN;
+					continue;
+				}
+				close(fd);
+			}
+		}
+
+		/* Create the task associated to the resolvers section */
+		if ((t = task_new_anywhere()) == NULL) {
+			ha_alert("resolvers '%s' : out of memory.\n", resolvers->id);
+			err_code |= (ERR_ALERT|ERR_ABORT);
+			goto err;
+		}
+
+		/* Update task's parameters */
+		t->process   = process_resolvers;
+		t->context   = resolvers;
+		resolvers->t = t;
+		task_wakeup(t, TASK_WOKEN_INIT);
+	}
+
+	for (px = proxies_list; px; px = px->next) {
+		struct server *srv;
+
+		if (px->flags & PR_FL_DISABLED) {
+			/* must not run and will not work anyway since
+			 * nothing in the proxy is initialized.
+			 */
+			continue;
+		}
+
+		for (srv = px->srv; srv; srv = srv->next) {
+			struct resolvers *resolvers;
+
+			if (!srv->resolvers_id)
+				continue;
+
+			if ((resolvers = find_resolvers_by_id(srv->resolvers_id)) == NULL) {
+				ha_alert("%s '%s', server '%s': unable to find required resolvers '%s'\n",
+					 proxy_type_str(px), px->id, srv->id, srv->resolvers_id);
+				err_code |= (ERR_ALERT|ERR_ABORT);
+				continue;
+			}
+			srv->resolvers = resolvers;
+			srv->srvrq_check = NULL;
+			if (srv->srvrq) {
+				if (!srv->srvrq->resolvers) {
+					srv->srvrq->resolvers = srv->resolvers;
+					if (resolv_link_resolution(srv->srvrq, OBJ_TYPE_SRVRQ, 0) == -1) {
+						ha_alert("%s '%s' : unable to set DNS resolution for server '%s'.\n",
+							 proxy_type_str(px), px->id, srv->id);
+						err_code |= (ERR_ALERT|ERR_ABORT);
+						continue;
+					}
+				}
+
+				srv->srvrq_check = task_new_anywhere();
+				if (!srv->srvrq_check) {
+					ha_alert("%s '%s' : unable to create SRVRQ task for server '%s'.\n",
+						 proxy_type_str(px), px->id, srv->id);
+					err_code |= (ERR_ALERT|ERR_ABORT);
+					goto err;
+				}
+				srv->srvrq_check->process = resolv_srvrq_expire_task;
+				srv->srvrq_check->context = srv;
+				srv->srvrq_check->expire = TICK_ETERNITY;
+			}
+			else if (resolv_link_resolution(srv, OBJ_TYPE_SERVER, 0) == -1) {
+				ha_alert("%s '%s', unable to set DNS resolution for server '%s'.\n",
+					 proxy_type_str(px), px->id, srv->id);
+				err_code |= (ERR_ALERT|ERR_ABORT);
+				continue;
+			}
+
+			srv->flags |= SRV_F_NON_PURGEABLE;
+		}
+	}
+
+	if (err_code & (ERR_ALERT|ERR_ABORT))
+		goto err;
+
+	leave_resolver_code();
+	return 0;
+  err:
+	leave_resolver_code();
+	resolvers_deinit();
+	return 1;
+
+}
+
+static int stats_dump_resolv_to_buffer(struct stconn *sc,
+                                    struct dns_nameserver *ns,
+                                    struct field *stats, size_t stats_count,
+                                    struct list *stat_modules)
+{
+	struct appctx *appctx = __sc_appctx(sc);
+	struct stats_module *mod;
+	size_t idx = 0;
+
+	memset(stats, 0, sizeof(struct field) * stats_count);
+
+	list_for_each_entry(mod, stat_modules, list) {
+		struct counters_node *counters = EXTRA_COUNTERS_GET(ns->extra_counters, mod);
+
+		mod->fill_stats(counters, stats + idx);
+		idx += mod->stats_count;
+	}
+
+	if (!stats_dump_one_line(stats, idx, appctx))
+		return 0;
+
+	if (!stats_putchk(appctx, NULL))
+		goto full;
+
+	return 1;
+
+  full:
+	return 0;
+}
+
+/* Uses <appctx.ctx.stats.obj1> as a pointer to the current resolver and <obj2>
+ * as a pointer to the current nameserver.
+ */
+int stats_dump_resolvers(struct stconn *sc,
+                         struct field *stats, size_t stats_count,
+                         struct list *stat_modules)
+{
+	struct appctx *appctx = __sc_appctx(sc);
+	struct show_stat_ctx *ctx = appctx->svcctx;
+	struct channel *rep = sc_ic(sc);
+	struct resolvers *resolver = ctx->obj1;
+	struct dns_nameserver *ns = ctx->obj2;
+
+	if (!resolver)
+		resolver = LIST_NEXT(&sec_resolvers, struct resolvers *, list);
+
+	/* dump resolvers */
+	list_for_each_entry_from(resolver, &sec_resolvers, list) {
+		ctx->obj1 = resolver;
+
+		ns = ctx->obj2 ?
+		     ctx->obj2 :
+		     LIST_NEXT(&resolver->nameservers, struct dns_nameserver *, list);
+
+		list_for_each_entry_from(ns, &resolver->nameservers, list) {
+			ctx->obj2 = ns;
+
+			if (buffer_almost_full(&rep->buf)) {
+				sc_need_room(sc, b_size(&rep->buf) / 2);
+				goto full;
+			}
+
+			if (!stats_dump_resolv_to_buffer(sc, ns,
+			                                 stats, stats_count,
+			                                 stat_modules)) {
+				return 0;
+			}
+		}
+
+		ctx->obj2 = NULL;
+	}
+
+	return 1;
+
+  full:
+	return 0;
+}
+
+void resolv_stats_clear_counters(int clrall, struct list *stat_modules)
+{
+	struct resolvers  *resolvers;
+	struct dns_nameserver *ns;
+	struct stats_module *mod;
+	void *counters;
+
+	list_for_each_entry(mod, stat_modules, list) {
+		if (!mod->clearable && !clrall)
+			continue;
+
+		list_for_each_entry(resolvers, &sec_resolvers, list) {
+			list_for_each_entry(ns, &resolvers->nameservers, list) {
+				counters = EXTRA_COUNTERS_GET(ns->extra_counters, mod);
+				memcpy(counters, mod->counters, mod->counters_size);
+			}
+		}
+	}
+
+}
+
+int resolv_allocate_counters(struct list *stat_modules)
+{
+	struct stats_module *mod;
+	struct resolvers *resolvers;
+	struct dns_nameserver *ns;
+
+	list_for_each_entry(resolvers, &sec_resolvers, list) {
+		list_for_each_entry(ns, &resolvers->nameservers, list) {
+			EXTRA_COUNTERS_REGISTER(&ns->extra_counters, COUNTERS_RSLV,
+			                        alloc_failed);
+
+			list_for_each_entry(mod, stat_modules, list) {
+				EXTRA_COUNTERS_ADD(mod,
+				                   ns->extra_counters,
+				                   mod->counters,
+				                   mod->counters_size);
+			}
+
+			EXTRA_COUNTERS_ALLOC(ns->extra_counters, alloc_failed);
+
+			list_for_each_entry(mod, stat_modules, list) {
+				memcpy(ns->extra_counters->data + mod->counters_off[ns->extra_counters->type],
+				       mod->counters, mod->counters_size);
+
+				/* Store the ns counters pointer */
+				if (strcmp(mod->name, "resolvers") == 0) {
+					ns->counters = (struct dns_counters *)ns->extra_counters->data + mod->counters_off[COUNTERS_RSLV];
+					ns->counters->id = ns->id;
+					ns->counters->pid = resolvers->id;
+				}
+			}
+		}
+	}
+
+	return 1;
+
+alloc_failed:
+	return 0;
+}
+
+/* if an arg is found, it sets the optional resolvers section pointer into a
+ * show_resolvers_ctx struct pointed to by svcctx, or NULL when dumping all.
+ */
+static int cli_parse_stat_resolvers(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	struct show_resolvers_ctx *ctx = applet_reserve_svcctx(appctx, sizeof(*ctx));
+	struct resolvers *presolvers;
+
+	if (*args[2]) {
+		list_for_each_entry(presolvers, &sec_resolvers, list) {
+			if (strcmp(presolvers->id, args[2]) == 0) {
+				ctx->forced_section = presolvers;
+				break;
+			}
+		}
+		if (ctx->forced_section == NULL)
+			return cli_err(appctx, "Can't find that resolvers section\n");
+	}
+	return 0;
+}
+
+/* Dumps counters from all resolvers section and associated name servers. It
+ * returns 0 if the output buffer is full and it needs to be called again,
+ * otherwise non-zero. It may limit itself to the resolver pointed to by the
+ * <resolvers> field of struct show_resolvers_ctx pointed to by <svcctx> if
+ * it's not null.
+ */
+static int cli_io_handler_dump_resolvers_to_buffer(struct appctx *appctx)
+{
+	struct show_resolvers_ctx *ctx = appctx->svcctx;
+	struct resolvers    *resolvers = ctx->resolvers;
+	struct dns_nameserver   *ns;
+
+	chunk_reset(&trash);
+
+	if (LIST_ISEMPTY(&sec_resolvers)) {
+		if (applet_putstr(appctx, "No resolvers found\n") == -1)
+			goto full;
+	}
+	else {
+		if (!resolvers)
+			resolvers = LIST_ELEM(sec_resolvers.n, typeof(resolvers), list);
+
+		list_for_each_entry_from(resolvers, &sec_resolvers, list) {
+			if (ctx->forced_section != NULL && ctx->forced_section != resolvers)
+				continue;
+
+			ctx->resolvers = resolvers;
+			ns = ctx->ns;
+
+			if (!ns) {
+				chunk_printf(&trash, "Resolvers section %s\n", resolvers->id);
+				if (applet_putchk(appctx, &trash) == -1)
+					goto full;
+
+				ns = LIST_ELEM(resolvers->nameservers.n, typeof(ns), list);
+				ctx->ns = ns;
+			}
+
+			list_for_each_entry_from(ns, &resolvers->nameservers, list) {
+				chunk_reset(&trash);
+				chunk_appendf(&trash, " nameserver %s:\n", ns->id);
+				chunk_appendf(&trash, "  sent:        %lld\n", ns->counters->sent);
+				chunk_appendf(&trash, "  snd_error:   %lld\n", ns->counters->snd_error);
+				chunk_appendf(&trash, "  valid:       %lld\n", ns->counters->app.resolver.valid);
+				chunk_appendf(&trash, "  update:      %lld\n", ns->counters->app.resolver.update);
+				chunk_appendf(&trash, "  cname:       %lld\n", ns->counters->app.resolver.cname);
+				chunk_appendf(&trash, "  cname_error: %lld\n", ns->counters->app.resolver.cname_error);
+				chunk_appendf(&trash, "  any_err:     %lld\n", ns->counters->app.resolver.any_err);
+				chunk_appendf(&trash, "  nx:          %lld\n", ns->counters->app.resolver.nx);
+				chunk_appendf(&trash, "  timeout:     %lld\n", ns->counters->app.resolver.timeout);
+				chunk_appendf(&trash, "  refused:     %lld\n", ns->counters->app.resolver.refused);
+				chunk_appendf(&trash, "  other:       %lld\n", ns->counters->app.resolver.other);
+				chunk_appendf(&trash, "  invalid:     %lld\n", ns->counters->app.resolver.invalid);
+				chunk_appendf(&trash, "  too_big:     %lld\n", ns->counters->app.resolver.too_big);
+				chunk_appendf(&trash, "  truncated:   %lld\n", ns->counters->app.resolver.truncated);
+				chunk_appendf(&trash, "  outdated:    %lld\n",  ns->counters->app.resolver.outdated);
+				if (applet_putchk(appctx, &trash) == -1)
+					goto full;
+				ctx->ns = ns;
+			}
+
+			ctx->ns = NULL;
+
+			/* was this the only section to dump ? */
+			if (ctx->forced_section)
+				break;
+		}
+	}
+
+	/* done! */
+	return 1;
+ full:
+	/* the output buffer is full, retry later */
+	return 0;
+}
+
+/* register cli keywords */
+static struct cli_kw_list cli_kws = {{ }, {
+		{ { "show", "resolvers", NULL }, "show resolvers [id]                     : dumps counters from all resolvers section and associated name servers",
+		  cli_parse_stat_resolvers, cli_io_handler_dump_resolvers_to_buffer },
+		{{},}
+	}
+};
+
+INITCALL1(STG_REGISTER, cli_register_kw, &cli_kws);
+
+/*
+ * Prepare <rule> for hostname resolution.
+ * Returns -1 in case of any allocation failure, 0 if not.
+ * On error, a global failure counter is also incremented.
+ */
+static int action_prepare_for_resolution(struct stream *stream, const char *hostname, int hostname_len)
+{
+	char *hostname_dn;
+	int   hostname_dn_len;
+	struct buffer *tmp = get_trash_chunk();
+
+	if (!hostname)
+		return 0;
+
+	hostname_dn     = tmp->area;
+	hostname_dn_len = resolv_str_to_dn_label(hostname, hostname_len,
+	                                         hostname_dn, tmp->size);
+	if (hostname_dn_len == -1)
+		goto err;
+
+
+	stream->resolv_ctx.hostname_dn     = strdup(hostname_dn);
+	stream->resolv_ctx.hostname_dn_len = hostname_dn_len;
+	if (!stream->resolv_ctx.hostname_dn)
+		goto err;
+
+	return 0;
+
+ err:
+	ha_free(&stream->resolv_ctx.hostname_dn);
+	resolv_failed_resolutions += 1;
+	return -1;
+}
+
+
+/*
+ * Execute the "do-resolution" action. May be called from {tcp,http}request.
+ */
+enum act_return resolv_action_do_resolve(struct act_rule *rule, struct proxy *px,
+					      struct session *sess, struct stream *s, int flags)
+{
+	struct resolv_resolution *resolution;
+	struct sample *smp;
+	struct resolv_requester *req;
+	struct resolvers  *resolvers;
+	struct resolv_resolution *res;
+	int exp, locked = 0;
+	enum act_return ret = ACT_RET_CONT;
+
+	resolvers = rule->arg.resolv.resolvers;
+
+	enter_resolver_code();
+
+	/* we have a response to our DNS resolution */
+ use_cache:
+	if (s->resolv_ctx.requester && s->resolv_ctx.requester->resolution != NULL) {
+		resolution = s->resolv_ctx.requester->resolution;
+		if (!locked) {
+			HA_SPIN_LOCK(DNS_LOCK, &resolvers->lock);
+			locked = 1;
+		}
+
+		if (resolution->step == RSLV_STEP_RUNNING)
+			goto yield;
+		if (resolution->step == RSLV_STEP_NONE) {
+			/* We update the variable only if we have a valid
+			 * response. If the response was not received yet, we
+			 * must yield.
+			 */
+			if (resolution->status == RSLV_STATUS_NONE)
+				goto yield;
+			if (resolution->status == RSLV_STATUS_VALID) {
+				struct sample smp;
+				short ip_sin_family = 0;
+				void *ip = NULL;
+
+				resolv_get_ip_from_response(&resolution->response, rule->arg.resolv.opts, NULL,
+							 0, &ip, &ip_sin_family, NULL);
+
+				switch (ip_sin_family) {
+				case AF_INET:
+					smp.data.type = SMP_T_IPV4;
+					memcpy(&smp.data.u.ipv4, ip, 4);
+					break;
+				case AF_INET6:
+					smp.data.type = SMP_T_IPV6;
+					memcpy(&smp.data.u.ipv6, ip, 16);
+					break;
+				default:
+					ip = NULL;
+				}
+
+				if (ip) {
+					smp.px = px;
+					smp.sess = sess;
+					smp.strm = s;
+
+					vars_set_by_name(rule->arg.resolv.varname, strlen(rule->arg.resolv.varname), &smp);
+				}
+			}
+		}
+
+		goto release_requester;
+	}
+
+	/* need to configure and start a new DNS resolution */
+	smp = sample_fetch_as_type(px, sess, s, SMP_OPT_DIR_REQ|SMP_OPT_FINAL, rule->arg.resolv.expr, SMP_T_STR);
+	if (smp == NULL)
+		goto end;
+
+	if (action_prepare_for_resolution(s, smp->data.u.str.area, smp->data.u.str.data) == -1)
+		goto end; /* on error, ignore the action */
+
+	s->resolv_ctx.parent = rule;
+
+	HA_SPIN_LOCK(DNS_LOCK, &resolvers->lock);
+	locked = 1;
+
+	resolv_link_resolution(s, OBJ_TYPE_STREAM, 0);
+
+	/* Check if there is a fresh enough response in the cache of our associated resolution */
+	req = s->resolv_ctx.requester;
+	if (!req || !req->resolution)
+		goto release_requester; /* on error, ignore the action */
+	res = req->resolution;
+
+	exp = tick_add(res->last_resolution, resolvers->hold.valid);
+	if (resolvers->t && res->status == RSLV_STATUS_VALID && tick_isset(res->last_resolution)
+	    && !tick_is_expired(exp, now_ms)) {
+		goto use_cache;
+	}
+
+	resolv_trigger_resolution(s->resolv_ctx.requester);
+
+  yield:
+	if (flags & ACT_OPT_FINAL)
+		goto release_requester;
+	ret = ACT_RET_YIELD;
+
+  end:
+	leave_resolver_code();
+	if (locked)
+		HA_SPIN_UNLOCK(DNS_LOCK, &resolvers->lock);
+	return ret;
+
+  release_requester:
+	ha_free(&s->resolv_ctx.hostname_dn);
+	s->resolv_ctx.hostname_dn_len = 0;
+	if (s->resolv_ctx.requester) {
+		_resolv_unlink_resolution(s->resolv_ctx.requester);
+		pool_free(resolv_requester_pool, s->resolv_ctx.requester);
+		s->resolv_ctx.requester = NULL;
+	}
+	goto end;
+}
+
+static void release_resolv_action(struct act_rule *rule)
+{
+	release_sample_expr(rule->arg.resolv.expr);
+	free(rule->arg.resolv.varname);
+	free(rule->arg.resolv.resolvers_id);
+	free(rule->arg.resolv.opts);
+}
+
+
+/* parse "do-resolve" action
+ * This action takes the following arguments:
+ *   do-resolve(<varName>,<resolversSectionName>,<resolvePrefer>) <expr>
+ *
+ *   - <varName> is the variable name where the result of the DNS resolution will be stored
+ *     (mandatory)
+ *   - <resolversSectionName> is the name of the resolvers section to use to perform the resolution
+ *     (mandatory)
+ *   - <resolvePrefer> can be either 'ipv4' or 'ipv6' and is the IP family we would like to resolve first
+ *     (optional), defaults to ipv6
+ *   - <expr> is an HAProxy expression used to fetch the name to be resolved
+ */
+enum act_parse_ret resolv_parse_do_resolve(const char **args, int *orig_arg, struct proxy *px, struct act_rule *rule, char **err)
+{
+	int cur_arg;
+	struct sample_expr *expr;
+	unsigned int where;
+	const char *beg, *end;
+
+	/* orig_arg points to the first argument, but we need to analyse the command itself first */
+	cur_arg = *orig_arg - 1;
+
+	/* locate varName, which is mandatory */
+	beg = strchr(args[cur_arg], '(');
+	if (beg == NULL)
+		goto do_resolve_parse_error;
+	beg = beg + 1; /* beg should points to the first character after opening parenthesis '(' */
+	end = strchr(beg, ',');
+	if (end == NULL)
+		goto do_resolve_parse_error;
+	rule->arg.resolv.varname = my_strndup(beg, end - beg);
+	if (rule->arg.resolv.varname == NULL)
+		goto do_resolve_parse_error;
+
+
+	/* locate resolversSectionName, which is mandatory.
+	 * Since next parameters are optional, the delimiter may be comma ','
+	 * or closing parenthesis ')'
+	 */
+	beg = end + 1;
+	end = strchr(beg, ',');
+	if (end == NULL)
+		end = strchr(beg, ')');
+	if (end == NULL)
+		goto do_resolve_parse_error;
+	rule->arg.resolv.resolvers_id = my_strndup(beg, end - beg);
+	if (rule->arg.resolv.resolvers_id == NULL)
+		goto do_resolve_parse_error;
+
+
+	rule->arg.resolv.opts = calloc(1, sizeof(*rule->arg.resolv.opts));
+	if (rule->arg.resolv.opts == NULL)
+		goto do_resolve_parse_error;
+
+	/* Default priority is ipv6 */
+	rule->arg.resolv.opts->family_prio = AF_INET6;
+
+	/* optional arguments accepted for now:
+	 *  ipv4 or ipv6
+	 */
+	while (*end != ')') {
+		beg = end + 1;
+		end = strchr(beg, ',');
+		if (end == NULL)
+			end = strchr(beg, ')');
+		if (end == NULL)
+			goto do_resolve_parse_error;
+
+		if (strncmp(beg, "ipv4", end - beg) == 0) {
+			rule->arg.resolv.opts->family_prio = AF_INET;
+		}
+		else if (strncmp(beg, "ipv6", end - beg) == 0) {
+			rule->arg.resolv.opts->family_prio = AF_INET6;
+		}
+		else {
+			goto do_resolve_parse_error;
+		}
+	}
+
+	cur_arg = cur_arg + 1;
+
+	expr = sample_parse_expr((char **)args, &cur_arg, px->conf.args.file, px->conf.args.line, err, &px->conf.args, NULL);
+	if (!expr)
+		goto do_resolve_parse_error;
+
+
+	where = 0;
+	if (px->cap & PR_CAP_FE)
+		where |= SMP_VAL_FE_HRQ_HDR;
+	if (px->cap & PR_CAP_BE)
+		where |= SMP_VAL_BE_HRQ_HDR;
+
+	if (!(expr->fetch->val & where)) {
+		memprintf(err,
+			  "fetch method '%s' extracts information from '%s', none of which is available here",
+			  args[cur_arg-1], sample_src_names(expr->fetch->use));
+		free(expr);
+		return ACT_RET_PRS_ERR;
+	}
+	rule->arg.resolv.expr = expr;
+	rule->action = ACT_CUSTOM;
+	rule->action_ptr = resolv_action_do_resolve;
+	*orig_arg = cur_arg;
+
+	rule->check_ptr = check_action_do_resolve;
+	rule->release_ptr = release_resolv_action;
+
+	return ACT_RET_PRS_OK;
+
+ do_resolve_parse_error:
+	ha_free(&rule->arg.resolv.varname);
+	ha_free(&rule->arg.resolv.resolvers_id);
+	memprintf(err, "Can't parse '%s'. Expects 'do-resolve(<varname>,<resolvers>[,<options>]) <expr>'. Available options are 'ipv4' and 'ipv6'",
+			args[cur_arg]);
+	return ACT_RET_PRS_ERR;
+}
+
+static struct action_kw_list http_req_kws = { { }, {
+	{ "do-resolve", resolv_parse_do_resolve, KWF_MATCH_PREFIX },
+	{ /* END */ }
+}};
+
+INITCALL1(STG_REGISTER, http_req_keywords_register, &http_req_kws);
+
+static struct action_kw_list tcp_req_cont_actions = {ILH, {
+	{ "do-resolve", resolv_parse_do_resolve, KWF_MATCH_PREFIX },
+	{ /* END */ }
+}};
+
+INITCALL1(STG_REGISTER, tcp_req_cont_keywords_register, &tcp_req_cont_actions);
+
+/* Check an "http-request do-resolve" action.
+ *
+ * The function returns 1 in success case, otherwise, it returns 0 and err is
+ * filled.
+ */
+int check_action_do_resolve(struct act_rule *rule, struct proxy *px, char **err)
+{
+	struct resolvers *resolvers = NULL;
+
+	if (rule->arg.resolv.resolvers_id == NULL) {
+		memprintf(err,"Proxy '%s': %s", px->id, "do-resolve action without resolvers");
+		return 0;
+	}
+
+	resolvers = find_resolvers_by_id(rule->arg.resolv.resolvers_id);
+	if (resolvers == NULL) {
+		memprintf(err,"Can't find resolvers section '%s' for do-resolve action", rule->arg.resolv.resolvers_id);
+		return 0;
+	}
+	rule->arg.resolv.resolvers = resolvers;
+
+	return 1;
+}
+
+void resolvers_setup_proxy(struct proxy *px)
+{
+	px->last_change = ns_to_sec(now_ns);
+	px->cap = PR_CAP_FE | PR_CAP_BE;
+	px->maxconn = 0;
+	px->conn_retries = 1;
+	px->timeout.server = TICK_ETERNITY;
+	px->timeout.client = TICK_ETERNITY;
+	px->timeout.connect = 1000; // by default same than timeout.resolve
+	px->accept = NULL;
+	px->options2 |= PR_O2_INDEPSTR | PR_O2_SMARTCON;
+}
+
+static int parse_resolve_conf(char **errmsg, char **warnmsg)
+{
+	struct dns_nameserver *newnameserver = NULL;
+	const char *whitespace = "\r\n\t ";
+	char *resolv_line = NULL;
+	int resolv_linenum = 0;
+	FILE *f = NULL;
+	char *address = NULL;
+	struct sockaddr_storage *sk = NULL;
+	struct protocol *proto;
+	int duplicate_name = 0;
+	int err_code = 0;
+
+	if ((resolv_line = malloc(sizeof(*resolv_line) * LINESIZE)) == NULL) {
+		memprintf(errmsg, "out of memory.\n");
+		err_code |= ERR_ALERT | ERR_FATAL;
+		goto resolv_out;
+	}
+
+	if ((f = fopen("/etc/resolv.conf", "r")) == NULL) {
+		if (errmsg)
+			memprintf(errmsg, "failed to open /etc/resolv.conf.");
+		err_code |= ERR_ALERT | ERR_FATAL;
+		goto resolv_out;
+	}
+
+	sk = calloc(1, sizeof(*sk));
+	if (sk == NULL) {
+		if (errmsg)
+			memprintf(errmsg, "parsing [/etc/resolv.conf:%d] : out of memory.", resolv_linenum);
+		err_code |= ERR_ALERT | ERR_FATAL;
+		goto resolv_out;
+	}
+
+	while (fgets(resolv_line, LINESIZE, f) != NULL) {
+		resolv_linenum++;
+		if (strncmp(resolv_line, "nameserver", 10) != 0)
+			continue;
+
+		address = strtok(resolv_line + 10, whitespace);
+		if (address == resolv_line + 10)
+			continue;
+
+		if (address == NULL) {
+			if (warnmsg)
+				memprintf(warnmsg, "%sparsing [/etc/resolv.conf:%d] : nameserver line is missing address.\n",
+				          *warnmsg ? *warnmsg : "", resolv_linenum);
+			err_code |= ERR_WARN;
+			continue;
+		}
+
+		duplicate_name = 0;
+		list_for_each_entry(newnameserver, &curr_resolvers->nameservers, list) {
+			if (strcmp(newnameserver->id, address) == 0) {
+				if (warnmsg)
+					memprintf(warnmsg, "%sParsing [/etc/resolv.conf:%d] : generated name for /etc/resolv.conf nameserver '%s' conflicts with another nameserver (declared at %s:%d), it appears to be a duplicate and will be excluded.\n",
+						  *warnmsg ? *warnmsg : "", resolv_linenum, address, newnameserver->conf.file, newnameserver->conf.line);
+				err_code |= ERR_WARN;
+				duplicate_name = 1;
+			}
+		}
+
+		if (duplicate_name)
+			continue;
+
+		memset(sk, 0, sizeof(*sk));
+		if (!str2ip2(address, sk, 1)) {
+			if (warnmsg)
+				memprintf(warnmsg, "%sparsing [/etc/resolv.conf:%d] : address '%s' could not be recognized, nameserver will be excluded.\n",
+				          *warnmsg ? *warnmsg : "", resolv_linenum, address);
+			err_code |= ERR_WARN;
+			continue;
+		}
+
+		set_host_port(sk, 53);
+
+		proto = protocol_lookup(sk->ss_family, PROTO_TYPE_STREAM, 0);
+		if (!proto || !proto->connect) {
+			if (warnmsg)
+				memprintf(warnmsg, "%sparsing [/etc/resolv.conf:%d] : '%s' : connect() not supported for this address family.\n",
+				          *warnmsg ? *warnmsg : "", resolv_linenum, address);
+			err_code |= ERR_WARN;
+			continue;
+		}
+
+		if ((newnameserver = calloc(1, sizeof(*newnameserver))) == NULL) {
+			if (errmsg)
+				memprintf(errmsg, "parsing [/etc/resolv.conf:%d] : out of memory.", resolv_linenum);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto resolv_out;
+		}
+
+		if (dns_dgram_init(newnameserver, sk) < 0) {
+			if (errmsg)
+				memprintf(errmsg, "parsing [/etc/resolv.conf:%d] : out of memory.", resolv_linenum);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			free(newnameserver);
+			goto resolv_out;
+		}
+
+		newnameserver->conf.file = strdup("/etc/resolv.conf");
+		if (newnameserver->conf.file == NULL) {
+			if (errmsg)
+				memprintf(errmsg, "parsing [/etc/resolv.conf:%d] : out of memory.", resolv_linenum);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			free(newnameserver);
+			goto resolv_out;
+		}
+
+		newnameserver->id = strdup(address);
+		if (newnameserver->id == NULL) {
+			if (errmsg)
+				memprintf(errmsg, "parsing [/etc/resolv.conf:%d] : out of memory.", resolv_linenum);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			free((char *)newnameserver->conf.file);
+			free(newnameserver);
+			goto resolv_out;
+		}
+
+		newnameserver->parent = curr_resolvers;
+		newnameserver->process_responses = resolv_process_responses;
+		newnameserver->conf.line = resolv_linenum;
+		LIST_APPEND(&curr_resolvers->nameservers, &newnameserver->list);
+	}
+
+resolv_out:
+	free(sk);
+	free(resolv_line);
+	if (f != NULL)
+		fclose(f);
+
+	return err_code;
+}
+
+static int resolvers_new(struct resolvers **resolvers, const char *id, const char *file, int linenum)
+{
+	struct resolvers *r = NULL;
+	struct proxy *p = NULL;
+	int err_code = 0;
+
+	if ((r = calloc(1, sizeof(*r))) == NULL) {
+		err_code |= ERR_ALERT | ERR_ABORT;
+		goto out;
+	}
+
+	/* allocate new proxy to tcp servers */
+	p = calloc(1, sizeof *p);
+	if (!p) {
+		err_code |= ERR_ALERT | ERR_FATAL;
+		goto out;
+	}
+
+	init_new_proxy(p);
+	resolvers_setup_proxy(p);
+	p->parent = r;
+	p->id = strdup(id);
+	p->conf.args.file = p->conf.file = strdup(file);
+	p->conf.args.line = p->conf.line = linenum;
+	r->px = p;
+
+	/* default values */
+	LIST_APPEND(&sec_resolvers, &r->list);
+	r->conf.file = strdup(file);
+	r->conf.line = linenum;
+	r->id = strdup(id);
+	r->query_ids = EB_ROOT;
+	/* default maximum response size */
+	r->accepted_payload_size = 512;
+	/* default hold period for nx, other, refuse and timeout is 30s */
+	r->hold.nx = 30000;
+	r->hold.other = 30000;
+	r->hold.refused = 30000;
+	r->hold.timeout = 30000;
+	r->hold.obsolete = 0;
+	/* default hold period for valid is 10s */
+	r->hold.valid = 10000;
+	r->timeout.resolve = 1000;
+	r->timeout.retry   = 1000;
+	r->resolve_retries = 3;
+	LIST_INIT(&r->nameservers);
+	LIST_INIT(&r->resolutions.curr);
+	LIST_INIT(&r->resolutions.wait);
+	HA_SPIN_INIT(&r->lock);
+
+	*resolvers = r;
+
+out:
+	if (err_code & (ERR_FATAL|ERR_ABORT)) {
+		ha_free(&r);
+		ha_free(&p);
+	}
+
+	return err_code;
+}
+
+
+/*
+ * Parse a <resolvers> section.
+ * Returns the error code, 0 if OK, or any combination of :
+ *  - ERR_ABORT: must abort ASAP
+ *  - ERR_FATAL: we can continue parsing but not start the service
+ *  - ERR_WARN: a warning has been emitted
+ *  - ERR_ALERT: an alert has been emitted
+ * Only the two first ones can stop processing, the two others are just
+ * indicators.
+ */
+int cfg_parse_resolvers(const char *file, int linenum, char **args, int kwm)
+{
+	const char *err;
+	int err_code = 0;
+	char *errmsg = NULL;
+	char *warnmsg = NULL;
+
+	if (strcmp(args[0], "resolvers") == 0) { /* new resolvers section */
+		if (!*args[1]) {
+			ha_alert("parsing [%s:%d] : missing name for resolvers section.\n", file, linenum);
+			err_code |= ERR_ALERT | ERR_ABORT;
+			goto out;
+		}
+
+		err = invalid_char(args[1]);
+		if (err) {
+			ha_alert("parsing [%s:%d] : character '%c' is not permitted in '%s' name '%s'.\n",
+				 file, linenum, *err, args[0], args[1]);
+			err_code |= ERR_ALERT | ERR_ABORT;
+			goto out;
+		}
+
+		list_for_each_entry(curr_resolvers, &sec_resolvers, list) {
+			/* Error if two resolvers owns the same name */
+			if (strcmp(curr_resolvers->id, args[1]) == 0) {
+				ha_alert("Parsing [%s:%d]: resolvers '%s' has same name as another resolvers (declared at %s:%d).\n",
+					 file, linenum, args[1], curr_resolvers->conf.file, curr_resolvers->conf.line);
+				err_code |= ERR_ALERT | ERR_ABORT;
+			}
+		}
+
+		err_code |= resolvers_new(&curr_resolvers, args[1], file, linenum);
+		if (err_code & ERR_ALERT) {
+			ha_alert("parsing [%s:%d] : out of memory.\n", file, linenum);
+			goto out;
+		}
+
+	}
+	else if (strcmp(args[0], "nameserver") == 0) { /* nameserver definition */
+		struct dns_nameserver *newnameserver = NULL;
+		struct sockaddr_storage *sk;
+		int port1, port2;
+		struct protocol *proto;
+
+		if (!*args[2]) {
+			ha_alert("parsing [%s:%d] : '%s' expects <name> and <addr>[:<port>] as arguments.\n",
+				 file, linenum, args[0]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+
+		err = invalid_char(args[1]);
+		if (err) {
+			ha_alert("parsing [%s:%d] : character '%c' is not permitted in server name '%s'.\n",
+				 file, linenum, *err, args[1]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+
+		list_for_each_entry(newnameserver, &curr_resolvers->nameservers, list) {
+			/* Error if two resolvers owns the same name */
+			if (strcmp(newnameserver->id, args[1]) == 0) {
+				ha_alert("Parsing [%s:%d]: nameserver '%s' has same name as another nameserver (declared at %s:%d).\n",
+					 file, linenum, args[1], newnameserver->conf.file, newnameserver->conf.line);
+				err_code |= ERR_ALERT | ERR_FATAL;
+			}
+		}
+
+		sk = str2sa_range(args[2], NULL, &port1, &port2, NULL, &proto, NULL,
+		                  &errmsg, NULL, NULL, PA_O_RESOLVE | PA_O_PORT_OK | PA_O_PORT_MAND | PA_O_DGRAM | PA_O_STREAM | PA_O_DEFAULT_DGRAM);
+		if (!sk) {
+			ha_alert("parsing [%s:%d] : '%s %s' : %s\n", file, linenum, args[0], args[1], errmsg);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+
+		if ((newnameserver = calloc(1, sizeof(*newnameserver))) == NULL) {
+			ha_alert("parsing [%s:%d] : out of memory.\n", file, linenum);
+			err_code |= ERR_ALERT | ERR_ABORT;
+			goto out;
+		}
+
+		if (proto && proto->xprt_type == PROTO_TYPE_STREAM) {
+			err_code |= parse_server(file, linenum, args, curr_resolvers->px, NULL,
+			                         SRV_PARSE_PARSE_ADDR|SRV_PARSE_INITIAL_RESOLVE);
+			if (err_code & (ERR_FATAL|ERR_ABORT)) {
+				err_code |= ERR_ABORT;
+				goto out;
+			}
+
+			if (dns_stream_init(newnameserver, curr_resolvers->px->srv) < 0) {
+				ha_alert("parsing [%s:%d] : out of memory.\n", file, linenum);
+				err_code |= ERR_ALERT|ERR_ABORT;
+				goto out;
+			}
+		}
+		else if (dns_dgram_init(newnameserver, sk) < 0) {
+			ha_alert("parsing [%s:%d] : out of memory.\n", file, linenum);
+			err_code |= ERR_ALERT | ERR_ABORT;
+			goto out;
+		}
+
+		if ((newnameserver->conf.file = strdup(file)) == NULL) {
+			ha_alert("parsing [%s:%d] : out of memory.\n", file, linenum);
+			err_code |= ERR_ALERT | ERR_ABORT;
+			goto out;
+		}
+
+		if ((newnameserver->id = strdup(args[1])) == NULL) {
+			ha_alert("parsing [%s:%d] : out of memory.\n", file, linenum);
+			err_code |= ERR_ALERT | ERR_ABORT;
+			goto out;
+		}
+
+		newnameserver->parent = curr_resolvers;
+		newnameserver->process_responses = resolv_process_responses;
+		newnameserver->conf.line = linenum;
+		/* the nameservers are linked backward first */
+		LIST_APPEND(&curr_resolvers->nameservers, &newnameserver->list);
+	}
+	else if (strcmp(args[0], "parse-resolv-conf") == 0) {
+		err_code |= parse_resolve_conf(&errmsg, &warnmsg);
+		if (err_code & ERR_WARN) {
+			indent_msg(&warnmsg, 8);
+			ha_warning("parsing [%s:%d]: %s\n", file, linenum, warnmsg);
+			ha_free(&warnmsg);
+		}
+		if (err_code & ERR_ALERT) {
+			indent_msg(&errmsg, 8);
+			ha_alert("parsing [%s:%d]: %s\n", file, linenum, errmsg);
+			ha_free(&errmsg);
+			goto out;
+		}
+	}
+	else if (strcmp(args[0], "hold") == 0) { /* hold periods */
+		const char *res;
+		unsigned int time;
+
+		if (!*args[2]) {
+			ha_alert("parsing [%s:%d] : '%s' expects an <event> and a <time> as arguments.\n",
+				 file, linenum, args[0]);
+			ha_alert("<event> can be either 'valid', 'nx', 'refused', 'timeout', or 'other'\n");
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+		res = parse_time_err(args[2], &time, TIME_UNIT_MS);
+		if (res == PARSE_TIME_OVER) {
+			ha_alert("parsing [%s:%d]: timer overflow in argument <%s> to <%s>, maximum value is 2147483647 ms (~24.8 days).\n",
+			         file, linenum, args[1], args[0]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+		else if (res == PARSE_TIME_UNDER) {
+			ha_alert("parsing [%s:%d]: timer underflow in argument <%s> to <%s>, minimum non-null value is 1 ms.\n",
+			         file, linenum, args[1], args[0]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+		else if (res) {
+			ha_alert("parsing [%s:%d]: unexpected character '%c' in argument to <%s>.\n",
+				 file, linenum, *res, args[0]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+		if (strcmp(args[1], "nx") == 0)
+			curr_resolvers->hold.nx = time;
+		else if (strcmp(args[1], "other") == 0)
+			curr_resolvers->hold.other = time;
+		else if (strcmp(args[1], "refused") == 0)
+			curr_resolvers->hold.refused = time;
+		else if (strcmp(args[1], "timeout") == 0)
+			curr_resolvers->hold.timeout = time;
+		else if (strcmp(args[1], "valid") == 0)
+			curr_resolvers->hold.valid = time;
+		else if (strcmp(args[1], "obsolete") == 0)
+			curr_resolvers->hold.obsolete = time;
+		else {
+			ha_alert("parsing [%s:%d] : '%s' unknown <event>: '%s', expects either 'nx', 'timeout', 'valid', 'obsolete' or 'other'.\n",
+				 file, linenum, args[0], args[1]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+
+	}
+	else if (strcmp(args[0], "accepted_payload_size") == 0) {
+		int i = 0;
+
+		if (!*args[1]) {
+			ha_alert("parsing [%s:%d] : '%s' expects <nb> as argument.\n",
+				 file, linenum, args[0]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+
+		i = atoi(args[1]);
+		if (i < DNS_HEADER_SIZE || i > DNS_MAX_UDP_MESSAGE) {
+			ha_alert("parsing [%s:%d] : '%s' must be between %d and %d inclusive (was %s).\n",
+				 file, linenum, args[0], DNS_HEADER_SIZE, DNS_MAX_UDP_MESSAGE, args[1]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+
+		curr_resolvers->accepted_payload_size = i;
+	}
+	else if (strcmp(args[0], "resolution_pool_size") == 0) {
+		ha_alert("parsing [%s:%d] : '%s' directive is not supported anymore (it never appeared in a stable release).\n",
+			   file, linenum, args[0]);
+		err_code |= ERR_ALERT | ERR_FATAL;
+		goto out;
+	}
+	else if (strcmp(args[0], "resolve_retries") == 0) {
+		if (!*args[1]) {
+			ha_alert("parsing [%s:%d] : '%s' expects <nb> as argument.\n",
+				 file, linenum, args[0]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+		curr_resolvers->resolve_retries = atoi(args[1]);
+	}
+	else if (strcmp(args[0], "timeout") == 0) {
+		if (!*args[1]) {
+			ha_alert("parsing [%s:%d] : '%s' expects 'retry' or 'resolve' and <time> as arguments.\n",
+				 file, linenum, args[0]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+		else if (strcmp(args[1], "retry") == 0 ||
+			 strcmp(args[1], "resolve") == 0) {
+			const char *res;
+			unsigned int tout;
+
+			if (!*args[2]) {
+				ha_alert("parsing [%s:%d] : '%s %s' expects <time> as argument.\n",
+					 file, linenum, args[0], args[1]);
+				err_code |= ERR_ALERT | ERR_FATAL;
+				goto out;
+			}
+			res = parse_time_err(args[2], &tout, TIME_UNIT_MS);
+			if (res == PARSE_TIME_OVER) {
+				ha_alert("parsing [%s:%d]: timer overflow in argument <%s> to <%s %s>, maximum value is 2147483647 ms (~24.8 days).\n",
+					 file, linenum, args[2], args[0], args[1]);
+				err_code |= ERR_ALERT | ERR_FATAL;
+				goto out;
+			}
+			else if (res == PARSE_TIME_UNDER) {
+				ha_alert("parsing [%s:%d]: timer underflow in argument <%s> to <%s %s>, minimum non-null value is 1 ms.\n",
+					 file, linenum, args[2], args[0], args[1]);
+				err_code |= ERR_ALERT | ERR_FATAL;
+				goto out;
+			}
+			else if (res) {
+				ha_alert("parsing [%s:%d]: unexpected character '%c' in argument to <%s %s>.\n",
+					 file, linenum, *res, args[0], args[1]);
+				err_code |= ERR_ALERT | ERR_FATAL;
+				goto out;
+			}
+			if (args[1][2] == 't')
+				curr_resolvers->timeout.retry = tout;
+			else {
+				curr_resolvers->timeout.resolve = tout;
+				curr_resolvers->px->timeout.connect = tout;
+			}
+
+		}
+		else {
+			ha_alert("parsing [%s:%d] : '%s' expects 'retry' or 'resolve' and <time> as arguments got '%s'.\n",
+				 file, linenum, args[0], args[1]);
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+	}
+	else if (*args[0] != 0) {
+		ha_alert("parsing [%s:%d] : unknown keyword '%s' in '%s' section\n", file, linenum, args[0], cursection);
+		err_code |= ERR_ALERT | ERR_FATAL;
+		goto out;
+	}
+
+out:
+	free(errmsg);
+	free(warnmsg);
+	return err_code;
+}
+
+/* try to create a "default" resolvers section which uses "/etc/resolv.conf"
+ *
+ * This function is opportunistic and does not try to display errors or warnings.
+ */
+int resolvers_create_default()
+{
+	int err_code = 0;
+
+	if (global.mode & MODE_MWORKER_WAIT) /* does not create the section if in wait mode */
+		return 0;
+
+	/* if the section already exists, do nothing */
+	if (find_resolvers_by_id("default"))
+		return 0;
+
+	curr_resolvers = NULL;
+	err_code |= resolvers_new(&curr_resolvers, "default", "<internal>", 0);
+	if (err_code & ERR_CODE)
+		goto err;
+
+	curr_resolvers->conf.implicit = 1;
+
+	err_code |= parse_resolve_conf(NULL, NULL);
+	if (err_code & ERR_CODE)
+		goto err;
+	/* check if there was any nameserver in the resolvconf file */
+	if (LIST_ISEMPTY(&curr_resolvers->nameservers)) {
+		err_code |= ERR_FATAL;
+		goto err;
+	}
+
+err:
+	if (err_code & ERR_CODE) {
+		resolvers_destroy(curr_resolvers);
+		curr_resolvers = NULL;
+	}
+
+	/* we never return an error there, we only try to create this section
+	 * if that's possible */
+	return 0;
+}
+
+int cfg_post_parse_resolvers()
+{
+	int err_code = 0;
+	struct server *srv;
+
+	if (curr_resolvers) {
+
+		/* prepare forward server descriptors */
+		if (curr_resolvers->px) {
+			srv = curr_resolvers->px->srv;
+			while (srv) {
+				/* init ssl if needed */
+				if (srv->use_ssl == 1 && xprt_get(XPRT_SSL) && xprt_get(XPRT_SSL)->prepare_srv) {
+					if (xprt_get(XPRT_SSL)->prepare_srv(srv)) {
+						ha_alert("unable to prepare SSL for server '%s' in resolvers section '%s'.\n", srv->id, curr_resolvers->id);
+						err_code |= ERR_ALERT | ERR_FATAL;
+						break;
+					}
+				}
+				srv = srv->next;
+			}
+		}
+	}
+	curr_resolvers = NULL;
+	return err_code;
+}
+
+REGISTER_CONFIG_SECTION("resolvers",      cfg_parse_resolvers, cfg_post_parse_resolvers);
+REGISTER_POST_DEINIT(resolvers_deinit);
+REGISTER_CONFIG_POSTPARSER("dns runtime resolver", resolvers_finalize_config);
+REGISTER_PRE_CHECK(resolvers_create_default);