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resolvers.c
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/*
* 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/dns_ring.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/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>
#if defined(USE_PROMEX)
#include <promex/promex.h>
#endif
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 stat_col 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 int resolv_fill_stats(void *d, struct field *stats, unsigned int *selected_field)
{
struct dns_counters *counters = d;
unsigned int current_field = (selected_field != NULL ? *selected_field : 0);
for (; current_field < RSLV_STAT_END; current_field++) {
struct field metric = { 0 };
switch (current_field) {
case RSLV_STAT_ID:
metric = mkf_str(FO_CONFIG, counters->id);
break;
case RSLV_STAT_PID:
metric = mkf_str(FO_CONFIG, counters->pid);
break;
case RSLV_STAT_SENT:
metric = mkf_u64(FN_GAUGE, counters->sent);
break;
case RSLV_STAT_SND_ERROR:
metric = mkf_u64(FN_GAUGE, counters->snd_error);
break;
case RSLV_STAT_VALID:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.valid);
break;
case RSLV_STAT_UPDATE:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.update);
break;
case RSLV_STAT_CNAME:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.cname);
break;
case RSLV_STAT_CNAME_ERROR:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.cname_error);
break;
case RSLV_STAT_ANY_ERR:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.any_err);
break;
case RSLV_STAT_NX:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.nx);
break;
case RSLV_STAT_TIMEOUT:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.timeout);
break;
case RSLV_STAT_REFUSED:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.refused);
break;
case RSLV_STAT_OTHER:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.other);
break;
case RSLV_STAT_INVALID:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.invalid);
break;
case RSLV_STAT_TOO_BIG:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.too_big);
break;
case RSLV_STAT_TRUNCATED:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.truncated);
break;
case RSLV_STAT_OUTDATED:
metric = mkf_u64(FN_GAUGE, counters->app.resolver.outdated);
break;
default:
/* not used for frontends. If a specific metric
* is requested, return an error. Otherwise continue.
*/
if (selected_field != NULL)
return 0;
continue;
}
stats[current_field] = metric;
if (selected_field != NULL)
break;
}
return 1;
}
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 to the nameserver matching numerical <id> within <parent>
* resolver section. NULL is returned if no match is found.
*/
struct dns_nameserver *find_nameserver_by_resolvers_and_id(struct resolvers *parent, unsigned int id)
{
struct dns_nameserver *ns;
list_for_each_entry(ns, &parent->nameservers, list) {
if (ns->puid == id)
return ns;
}
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)
{
struct server_inetaddr srv_addr;
_resolv_unlink_resolution(srv->resolv_requester);
HA_SPIN_LOCK(SERVER_LOCK, &srv->lock);
srvrq_set_srv_down(srv);
ha_free(&srv->hostname);
ha_free(&srv->hostname_dn);
srv->hostname_dn_len = 0;
memset(&srv_addr, 0, sizeof(srv_addr));
/* unset server's addr AND port */
server_set_inetaddr(srv, &srv_addr, SERVER_INETADDR_UPDATER_NONE, NULL);
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) {
struct server_inetaddr srv_addr;
uint8_t ip_change = 0;
/* re-enable DNS resolution for this server by default */
srv->flags &= ~SRV_F_NO_RESOLUTION;
srv->srvrq_check->expire = TICK_ETERNITY;
server_get_inetaddr(srv, &srv_addr);
srv_addr.port.svc = item->port;
srv_addr.port.map = 0;
/* 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_addr.family = AF_INET;
srv_addr.addr.v4 = item->ar_item->data.in4.sin_addr;
break;
case DNS_RTYPE_AAAA:
srv_addr.family = AF_INET6;
srv_addr.addr.v6 = item->ar_item->data.in6.sin6_addr;
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);
ip_change = 1;
}
if (ip_change)
server_set_inetaddr_warn(srv, &srv_addr, SERVER_INETADDR_UPDATER_DNS_AR);
else
server_set_inetaddr(srv, &srv_addr, SERVER_INETADDR_UPDATER_NONE, NULL);
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);
}
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;