/src/haproxy/src/check.c

Source
/*
 * Health-checks functions.
 *
 * Copyright 2000-2009 Willy Tarreau <w@1wt.eu>
 * Copyright 2007-2009 Krzysztof Piotr Oledzki <ole@ans.pl>
 *
 * 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 <assert.h>
#include <ctype.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>

#include <haproxy/action.h>
#include <haproxy/api.h>
#include <haproxy/arg.h>
#include <haproxy/cfgparse.h>
#include <haproxy/check.h>
#include <haproxy/chunk.h>
#include <haproxy/counters.h>
#include <haproxy/dgram.h>
#include <haproxy/dynbuf.h>
#include <haproxy/extcheck.h>
#include <haproxy/fd.h>
#include <haproxy/global.h>
#include <haproxy/h1.h>
#include <haproxy/http.h>
#include <haproxy/http_htx.h>
#include <haproxy/htx.h>
#include <haproxy/istbuf.h>
#include <haproxy/list.h>
#include <haproxy/log.h>
#include <haproxy/mailers.h>
#include <haproxy/port_range.h>
#include <haproxy/proto_tcp.h>
#include <haproxy/protocol.h>
#include <haproxy/proxy.h>
#include <haproxy/queue.h>
#include <haproxy/regex.h>
#include <haproxy/resolvers.h>
#include <haproxy/sample.h>
#include <haproxy/server.h>
#include <haproxy/ssl_sock.h>
#include <haproxy/stats-t.h>
#include <haproxy/task.h>
#include <haproxy/tcpcheck.h>
#include <haproxy/thread.h>
#include <haproxy/time.h>
#include <haproxy/tools.h>
#include <haproxy/trace.h>
#include <haproxy/vars.h>

/* trace source and events */
static void check_trace(enum trace_level level, uint64_t mask,
      const struct trace_source *src,
      const struct ist where, const struct ist func,
      const void *a1, const void *a2, const void *a3, const void *a4);

/* The event representation is split like this :
 *   check  - check
 *
 * CHECK_EV_* macros are defined in <haproxy/check.h>
 */
static const struct trace_event check_trace_events[] = {
  { .mask = CHK_EV_TASK_WAKE,   .name = "task_wake",        .desc = "Check task woken up" },
  { .mask = CHK_EV_HCHK_START,  .name = "hchck_start",      .desc = "Health-check started" },
  { .mask = CHK_EV_HCHK_WAKE,   .name = "hchck_wake",       .desc = "Health-check woken up" },
  { .mask = CHK_EV_HCHK_RUN,    .name = "hchck_run",        .desc = "Health-check running" },
  { .mask = CHK_EV_HCHK_END,    .name = "hchck_end",        .desc = "Health-check terminated" },
  { .mask = CHK_EV_HCHK_SUCC,   .name = "hchck_succ",       .desc = "Health-check success" },
  { .mask = CHK_EV_HCHK_ERR,    .name = "hchck_err",        .desc = "Health-check failure" },

  { .mask = CHK_EV_TCPCHK_EVAL, .name = "tcp_check_eval",   .desc = "tcp-check rules evaluation" },
  { .mask = CHK_EV_TCPCHK_ERR,  .name = "tcp_check_err",    .desc = "tcp-check evaluation error" },
  { .mask = CHK_EV_TCPCHK_CONN, .name = "tcp_check_conn",   .desc = "tcp-check connection rule" },
  { .mask = CHK_EV_TCPCHK_SND,  .name = "tcp_check_send",   .desc = "tcp-check send rule" },
  { .mask = CHK_EV_TCPCHK_EXP,  .name = "tcp_check_expect", .desc = "tcp-check expect rule" },
  { .mask = CHK_EV_TCPCHK_ACT,  .name = "tcp_check_action", .desc = "tcp-check action rule" },

  { .mask = CHK_EV_RX_DATA,     .name = "rx_data",          .desc = "receipt of data" },
  { .mask = CHK_EV_RX_BLK,      .name = "rx_blk",           .desc = "receipt blocked" },
  { .mask = CHK_EV_RX_ERR,      .name = "rx_err",           .desc = "receipt error" },

  { .mask = CHK_EV_TX_DATA,     .name = "tx_data",          .desc = "transmission of data" },
  { .mask = CHK_EV_TX_BLK,      .name = "tx_blk",           .desc = "transmission blocked" },
  { .mask = CHK_EV_TX_ERR,      .name = "tx_err",           .desc = "transmission error" },

  {}
};

static const struct name_desc check_trace_lockon_args[4] = {
  /* arg1 */ { /* already used by the check */ },
  /* arg2 */ { },
  /* arg3 */ { },
  /* arg4 */ { }
};

static const struct name_desc check_trace_decoding[] = {
#define CHK_VERB_CLEAN    1
  { .name="clean",    .desc="only user-friendly stuff, generally suitable for level \"user\"" },
#define CHK_VERB_MINIMAL  2
  { .name="minimal",  .desc="report info on streams and connectors" },
#define CHK_VERB_SIMPLE   3
  { .name="simple",   .desc="add info on request and response channels" },
#define CHK_VERB_ADVANCED 4
  { .name="advanced", .desc="add info on channel's buffer for data and developer levels only" },
#define CHK_VERB_COMPLETE 5
  { .name="complete", .desc="add info on channel's buffer" },
  { /* end */ }
};

struct trace_source trace_check = {
  .name = IST("check"),
  .desc = "Health-check",
  .arg_def = TRC_ARG1_CHK,  // TRACE()'s first argument is always a stream
  .default_cb = check_trace,
  .known_events = check_trace_events,
  .lockon_args = check_trace_lockon_args,
  .decoding = check_trace_decoding,
  .report_events = ~0,  // report everything by default
};

#define TRACE_SOURCE &trace_check
INITCALL1(STG_REGISTER, trace_register_source, TRACE_SOURCE);


/* Dummy frontend used to create all checks sessions. */
struct proxy checks_fe;


static inline void check_trace_buf(const struct buffer *buf, size_t ofs, size_t len)
{
  size_t block1, block2;
  int line, ptr, newptr;

  block1 = b_contig_data(buf, ofs);
  block2 = 0;
  if (block1 > len)
    block1 = len;
  block2 = len - block1;

  ofs = b_peek_ofs(buf, ofs);

  line = 0;
  ptr = ofs;
  while (ptr < ofs + block1) {
    newptr = dump_text_line(&trace_buf, b_orig(buf), b_size(buf), ofs + block1, &line, ptr);
    if (newptr == ptr)
      break;
    ptr = newptr;
  }

  line = ptr = 0;
  while (ptr < block2) {
    newptr = dump_text_line(&trace_buf, b_orig(buf), b_size(buf), block2, &line, ptr);
    if (newptr == ptr)
      break;
    ptr = newptr;
  }
}

/* trace source and events */
static void check_trace(enum trace_level level, uint64_t mask,
      const struct trace_source *src,
      const struct ist where, const struct ist func,
      const void *a1, const void *a2, const void *a3, const void *a4)
{
  const struct check *check = a1;
  const struct server *srv = (check ? check->server : NULL);
  const size_t        *val = a4;
  const char *res;

  if (!check || src->verbosity < CHK_VERB_CLEAN)
    return;

  BUG_ON(!srv);
  chunk_appendf(&trace_buf, " : [%c] SRV=%s",
          ((check->type == PR_O2_EXT_CHK) ? 'E' : (check->state & CHK_ST_AGENT ? 'A' : 'H')),
          srv->id);

  chunk_appendf(&trace_buf, " status=%d/%d %s exp=%d",
          (check->health >= check->rise) ? check->health - check->rise + 1 : check->health,
          (check->health >= check->rise) ? check->fall : check->rise,
          (check->health >= check->rise) ? (srv->uweight ? "UP" : "DRAIN") : "DOWN",
          (check->task->expire ? TICKS_TO_MS(check->task->expire - now_ms) : 0));

  switch (check->result) {
  case CHK_RES_NEUTRAL: res = "-";     break;
  case CHK_RES_FAILED:   res = "FAIL"; break;
  case CHK_RES_PASSED:   res = "PASS"; break;
  case CHK_RES_CONDPASS: res = "COND"; break;
  default:               res = "UNK";  break;
  }

  if (src->verbosity == CHK_VERB_CLEAN)
    return;

  chunk_appendf(&trace_buf, " - last=%s(%d)/%s(%d)",
          get_check_status_info(check->status), check->status,
          res, check->result);

  /* Display the value to the 4th argument (level > STATE) */
  if (src->level > TRACE_LEVEL_STATE && val)
    chunk_appendf(&trace_buf, " - VAL=%lu", (long)*val);

  chunk_appendf(&trace_buf, " check=%p(0x%08x)", check, check->state);

  if (src->verbosity == CHK_VERB_MINIMAL)
    return;


  if (check->sc) {
    struct connection *conn = sc_conn(check->sc);

    chunk_appendf(&trace_buf, " - conn=%p(0x%08x)", conn, conn ? conn->flags : 0);
    chunk_appendf(&trace_buf, " sc=%p(0x%08x)", check->sc, check->sc->flags);
  }

  if (mask & CHK_EV_TCPCHK) {
    const char *type;

    switch (check->tcpcheck_rules->flags & TCPCHK_RULES_PROTO_CHK) {
      case TCPCHK_RULES_PGSQL_CHK: type = "PGSQL"; break;
      case TCPCHK_RULES_REDIS_CHK: type = "REDIS"; break;
      case TCPCHK_RULES_SMTP_CHK:  type = "SMTP";  break;
      case TCPCHK_RULES_HTTP_CHK:  type = "HTTP";  break;
      case TCPCHK_RULES_MYSQL_CHK: type = "MYSQL"; break;
      case TCPCHK_RULES_LDAP_CHK:  type = "LDAP";  break;
      case TCPCHK_RULES_SSL3_CHK:  type = "SSL3";  break;
      case TCPCHK_RULES_AGENT_CHK: type = "AGENT"; break;
      case TCPCHK_RULES_SPOP_CHK:  type = "SPOP";  break;
      case TCPCHK_RULES_TCP_CHK:   type = "TCP";   break;
      default:                     type = "???"; break;
    }
    if (check->current_step)
      chunk_appendf(&trace_buf, " - tcp-check=(%s,%d)", type, tcpcheck_get_step_id(check, NULL));
    else
      chunk_appendf(&trace_buf, " - tcp-check=(%s,-)", type);
  }

  /* Display bi and bo buffer info (level > USER & verbosity > SIMPLE) */
  if (src->level > TRACE_LEVEL_USER) {
    const struct buffer *buf = NULL;

    chunk_appendf(&trace_buf, " bi=%u@%p+%u/%u",
            (unsigned int)b_data(&check->bi), b_orig(&check->bi),
            (unsigned int)b_head_ofs(&check->bi), (unsigned int)b_size(&check->bi));
    chunk_appendf(&trace_buf, " bo=%u@%p+%u/%u",
            (unsigned int)b_data(&check->bo), b_orig(&check->bo),
            (unsigned int)b_head_ofs(&check->bo), (unsigned int)b_size(&check->bo));

    if (src->verbosity >= CHK_VERB_ADVANCED && (mask & (CHK_EV_RX)))
      buf = (b_is_null(&check->bi) ? NULL : &check->bi);
    else if (src->verbosity >= CHK_VERB_ADVANCED && (mask & (CHK_EV_TX)))
      buf = (b_is_null(&check->bo) ? NULL : &check->bo);

    if (buf) {
      if ((check->tcpcheck_rules->flags & TCPCHK_RULES_PROTO_CHK) == TCPCHK_RULES_HTTP_CHK) {
        int full = (src->verbosity == CHK_VERB_COMPLETE);

        chunk_memcat(&trace_buf, "\n\t", 2);
        htx_dump(&trace_buf, htxbuf(buf), full);
      }
      else {
        int max = ((src->verbosity == CHK_VERB_COMPLETE) ? 1024 : 256);

        chunk_memcat(&trace_buf, "\n", 1);
        if (b_data(buf) > max) {
          check_trace_buf(buf, 0, max);
          chunk_memcat(&trace_buf, "  ...\n", 6);
        }
        else
          check_trace_buf(buf, 0, b_data(buf));
      }

    }
  }

}


/**************************************************************************/
/************************ Handle check results ****************************/
/**************************************************************************/
struct check_status {
  short result;     /* one of SRV_CHK_* */
  char *info;     /* human readable short info */
  char *desc;     /* long description */
};

struct analyze_status {
  char *desc;       /* description */
  unsigned char lr[HANA_OBS_SIZE];  /* result for l4/l7: 0 = ignore, 1 - error, 2 - OK */
};

static const struct check_status check_statuses[HCHK_STATUS_SIZE] = {
  [HCHK_STATUS_UNKNOWN] = { CHK_RES_UNKNOWN,  "UNK",     "Unknown" },
  [HCHK_STATUS_INI] = { CHK_RES_UNKNOWN,  "INI",     "Initializing" },
  [HCHK_STATUS_START] = { /* SPECIAL STATUS*/ },

  /* Below we have finished checks */
  [HCHK_STATUS_CHECKED] = { CHK_RES_NEUTRAL,  "CHECKED", "No status change" },
  [HCHK_STATUS_HANA]  = { CHK_RES_FAILED,   "HANA",    "Health analyze" },

  [HCHK_STATUS_SOCKERR] = { CHK_RES_FAILED,   "SOCKERR", "Socket error" },

  [HCHK_STATUS_L4OK]  = { CHK_RES_PASSED,   "L4OK",    "Layer4 check passed" },
  [HCHK_STATUS_L4TOUT]  = { CHK_RES_FAILED,   "L4TOUT",  "Layer4 timeout" },
  [HCHK_STATUS_L4CON] = { CHK_RES_FAILED,   "L4CON",   "Layer4 connection problem" },

  [HCHK_STATUS_L6OK]  = { CHK_RES_PASSED,   "L6OK",    "Layer6 check passed" },
  [HCHK_STATUS_L6TOUT]  = { CHK_RES_FAILED,   "L6TOUT",  "Layer6 timeout" },
  [HCHK_STATUS_L6RSP] = { CHK_RES_FAILED,   "L6RSP",   "Layer6 invalid response" },

  [HCHK_STATUS_L7TOUT]  = { CHK_RES_FAILED,   "L7TOUT",  "Layer7 timeout" },
  [HCHK_STATUS_L7RSP] = { CHK_RES_FAILED,   "L7RSP",   "Layer7 invalid response" },

  [HCHK_STATUS_L57DATA] = { /* DUMMY STATUS */ },

  [HCHK_STATUS_L7OKD] = { CHK_RES_PASSED,   "L7OK",    "Layer7 check passed" },
  [HCHK_STATUS_L7OKCD]  = { CHK_RES_CONDPASS, "L7OKC",   "Layer7 check conditionally passed" },
  [HCHK_STATUS_L7STS] = { CHK_RES_FAILED,   "L7STS",   "Layer7 wrong status" },

  [HCHK_STATUS_PROCERR] = { CHK_RES_FAILED,   "PROCERR",  "External check error" },
  [HCHK_STATUS_PROCTOUT]  = { CHK_RES_FAILED,   "PROCTOUT", "External check timeout" },
  [HCHK_STATUS_PROCOK]  = { CHK_RES_PASSED,   "PROCOK",   "External check passed" },
};

static const struct analyze_status analyze_statuses[HANA_STATUS_SIZE] = {   /* 0: ignore, 1: error, 2: OK */
  [HANA_STATUS_UNKNOWN]   = { "Unknown",                         { 0, 0 }},

  [HANA_STATUS_L4_OK]   = { "L4 successful connection",        { 2, 0 }},
  [HANA_STATUS_L4_ERR]    = { "L4 unsuccessful connection",      { 1, 1 }},

  [HANA_STATUS_HTTP_OK]   = { "Correct http response",           { 0, 2 }},
  [HANA_STATUS_HTTP_STS]    = { "Wrong http response",             { 0, 1 }},
  [HANA_STATUS_HTTP_HDRRSP] = { "Invalid http response (headers)", { 0, 1 }},
  [HANA_STATUS_HTTP_RSP]    = { "Invalid http response",           { 0, 1 }},

  [HANA_STATUS_HTTP_READ_ERROR] = { "Read error (http)",               { 0, 1 }},
  [HANA_STATUS_HTTP_READ_TIMEOUT] = { "Read timeout (http)",             { 0, 1 }},
  [HANA_STATUS_HTTP_BROKEN_PIPE]  = { "Close from server (http)",        { 0, 1 }},
};

/* checks if <err> is a real error for errno or one that can be ignored, and
 * return 0 for these ones or <err> for real ones.
 */
static inline int unclean_errno(int err)
{
  if (err == EAGAIN || err == EWOULDBLOCK || err == EINPROGRESS ||
      err == EISCONN || err == EALREADY)
    return 0;
  return err;
}

/* Converts check_status code to result code */
short get_check_status_result(short check_status)
{
  if (check_status < HCHK_STATUS_SIZE)
    return check_statuses[check_status].result;
  else
    return check_statuses[HCHK_STATUS_UNKNOWN].result;
}

/* Converts check_status code to description */
const char *get_check_status_description(short check_status) {

  const char *desc;

  if (check_status < HCHK_STATUS_SIZE)
    desc = check_statuses[check_status].desc;
  else
    desc = NULL;

  if (desc && *desc)
    return desc;
  else
    return check_statuses[HCHK_STATUS_UNKNOWN].desc;
}

/* Converts check_status code to short info */
const char *get_check_status_info(short check_status)
{
  const char *info;

  if (check_status < HCHK_STATUS_SIZE)
    info = check_statuses[check_status].info;
  else
    info = NULL;

  if (info && *info)
    return info;
  else
    return check_statuses[HCHK_STATUS_UNKNOWN].info;
}

/* Convert analyze_status to description */
const char *get_analyze_status(short analyze_status) {

  const char *desc;

  if (analyze_status < HANA_STATUS_SIZE)
    desc = analyze_statuses[analyze_status].desc;
  else
    desc = NULL;

  if (desc && *desc)
    return desc;
  else
    return analyze_statuses[HANA_STATUS_UNKNOWN].desc;
}

/* append check info to buffer msg */
void check_append_info(struct buffer *msg, struct check *check)
{
  if (!check)
    return;
  chunk_appendf(msg, ", reason: %s", get_check_status_description(check->status));

  if (check->status >= HCHK_STATUS_L57DATA)
    chunk_appendf(msg, ", code: %d", check->code);

  if (check->desc[0]) {
    struct buffer src;

    chunk_appendf(msg, ", info: \"");

    chunk_initlen(&src, check->desc, 0, strlen(check->desc));
    chunk_asciiencode(msg, &src, '"');

    chunk_appendf(msg, "\"");
  }

  if (check->duration >= 0)
    chunk_appendf(msg, ", check duration: %ldms", check->duration);
}

/* Sets check->status, update check->duration and fill check->result with an
 * adequate CHK_RES_* value. The new check->health is computed based on the
 * result.
 *
 * Shows information in logs about failed health check if server is UP or
 * succeeded health checks if server is DOWN.
 */
void set_server_check_status(struct check *check, short status, const char *desc)
{
  struct server *s = check->server;
  short prev_status = check->status;
  int report = (status != prev_status) ? 1 : 0;

  TRACE_POINT(CHK_EV_HCHK_RUN, check);

  if (status == HCHK_STATUS_START) {
    check->result = CHK_RES_UNKNOWN;  /* no result yet */
    check->desc[0] = '\0';
    check->start = now_ns;
    return;
  }

  if (!check->status)
    return;

  if (desc && *desc) {
    strncpy(check->desc, desc, HCHK_DESC_LEN-1);
    check->desc[HCHK_DESC_LEN-1] = '\0';
  } else
    check->desc[0] = '\0';

  check->status = status;
  if (check_statuses[status].result)
    check->result = check_statuses[status].result;

  if (status == HCHK_STATUS_HANA)
    check->duration = -1;
  else if (check->start) {
    /* set_server_check_status() may be called more than once */
    check->duration = ns_to_ms(now_ns - check->start);
    check->start = 0;
  }

  /* no change is expected if no state change occurred */
  if (check->result == CHK_RES_NEUTRAL)
    return;

  /* If the check was really just sending a mail, it won't have an
   * associated server, so we're done now.
   */
  if (!s)
      return;

  switch (check->result) {
  case CHK_RES_FAILED:
    /* Failure to connect to the agent as a secondary check should not
     * cause the server to be marked down.
     */
    if ((!(check->state & CHK_ST_AGENT) ||
        (check->status >= HCHK_STATUS_L57DATA)) &&
        (check->health > 0)) {
      if (s->counters.shared.tg[tgid - 1])
        _HA_ATOMIC_INC(&s->counters.shared.tg[tgid - 1]->failed_checks);
      report = 1;
      check->health--;
      if (check->health < check->rise)
        check->health = 0;
    }
    break;

  case CHK_RES_PASSED:
  case CHK_RES_CONDPASS:
    if (check->health < check->rise + check->fall - 1) {
      report = 1;
      check->health++;

      if (check->health >= check->rise)
        check->health = check->rise + check->fall - 1; /* OK now */
    }

    /* clear consecutive_errors if observing is enabled */
    if (s->onerror)
      HA_ATOMIC_STORE(&s->consecutive_errors, 0);
    break;

  default:
    break;
  }

  if (report)
    srv_event_hdl_publish_check(s, check);

  if (s->proxy->options2 & PR_O2_LOGHCHKS && report) {
    chunk_printf(&trash,
                 "%s check for %sserver %s/%s %s%s",
           (check->state & CHK_ST_AGENT) ? "Agent" : "Health",
                 s->flags & SRV_F_BACKUP ? "backup " : "",
                 s->proxy->id, s->id,
                 (check->result == CHK_RES_CONDPASS) ? "conditionally ":"",
                 (check->result >= CHK_RES_PASSED)   ? "succeeded" : "failed");

    check_append_info(&trash, check);

    chunk_appendf(&trash, ", status: %d/%d %s",
                 (check->health >= check->rise) ? check->health - check->rise + 1 : check->health,
                 (check->health >= check->rise) ? check->fall : check->rise,
           (check->health >= check->rise) ? (s->uweight ? "UP" : "DRAIN") : "DOWN");

    ha_warning("%s.\n", trash.area);
    send_log(s->proxy, LOG_NOTICE, "%s.\n", trash.area);
  }
}

static inline enum srv_op_st_chg_cause check_notify_cause(struct check *check)
{
  struct server *s = check->server;

  /* We only report a cause for the check if we did not do so previously */
  if (!s->track && !(s->proxy->options2 & PR_O2_LOGHCHKS))
    return (check->state & CHK_ST_AGENT) ? SRV_OP_STCHGC_AGENT : SRV_OP_STCHGC_HEALTH;
  return SRV_OP_STCHGC_NONE;
}

/* Marks the check <check>'s server down if the current check is already failed
 * and the server is not down yet nor in maintenance.
 */
void check_notify_failure(struct check *check)
{
  struct server *s = check->server;

  /* The agent secondary check should only cause a server to be marked
   * as down if check->status is HCHK_STATUS_L7STS, which indicates
   * that the agent returned "fail", "stopped" or "down".
   * The implication here is that failure to connect to the agent
   * as a secondary check should not cause the server to be marked
   * down. */
  if ((check->state & CHK_ST_AGENT) && check->status != HCHK_STATUS_L7STS)
    return;

  if (check->health > 0)
    return;

  TRACE_STATE("health-check failed, set server DOWN", CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
  srv_set_stopped(s, check_notify_cause(check));
}

/* Marks the check <check> as valid and tries to set its server up, provided
 * it isn't in maintenance, it is not tracking a down server and other checks
 * comply. The rule is simple : by default, a server is up, unless any of the
 * following conditions is true :
 *   - health check failed (check->health < rise)
 *   - agent check failed (agent->health < rise)
 *   - the server tracks a down server (track && track->state == STOPPED)
 * Note that if the server has a slowstart, it will switch to STARTING instead
 * of RUNNING. Also, only the health checks support the nolb mode, so the
 * agent's success may not take the server out of this mode.
 */
void check_notify_success(struct check *check)
{
  struct server *s = check->server;

  if (s->next_admin & SRV_ADMF_MAINT)
    return;

  if (s->track && s->track->next_state == SRV_ST_STOPPED)
    return;

  if ((s->check.state & CHK_ST_ENABLED) && (s->check.health < s->check.rise))
    return;

  if ((s->agent.state & CHK_ST_ENABLED) && (s->agent.health < s->agent.rise))
    return;

  if ((check->state & CHK_ST_AGENT) && s->next_state == SRV_ST_STOPPING)
    return;

  TRACE_STATE("health-check succeeded, set server RUNNING", CHK_EV_HCHK_END|CHK_EV_HCHK_SUCC, check);
  srv_set_running(s, check_notify_cause(check));
}

/* Marks the check <check> as valid and tries to set its server into stopping mode
 * if it was running or starting, and provided it isn't in maintenance and other
 * checks comply. The conditions for the server to be marked in stopping mode are
 * the same as for it to be turned up. Also, only the health checks support the
 * nolb mode.
 */
void check_notify_stopping(struct check *check)
{
  struct server *s = check->server;

  if (s->next_admin & SRV_ADMF_MAINT)
    return;

  if (check->state & CHK_ST_AGENT)
    return;

  if (s->track && s->track->next_state == SRV_ST_STOPPED)
    return;

  if ((s->check.state & CHK_ST_ENABLED) && (s->check.health < s->check.rise))
    return;

  if ((s->agent.state & CHK_ST_ENABLED) && (s->agent.health < s->agent.rise))
    return;

  TRACE_STATE("health-check condionnaly succeeded, set server STOPPING", CHK_EV_HCHK_END|CHK_EV_HCHK_SUCC, check);
  srv_set_stopping(s, check_notify_cause(check));
}

/* note: use health_adjust() only, which first checks that the observe mode is
 * enabled. This will take the server lock if needed.
 */
void __health_adjust(struct server *s, short status)
{
  int failed;

  if (s->observe >= HANA_OBS_SIZE)
    return;

  if (status >= HANA_STATUS_SIZE || !analyze_statuses[status].desc)
    return;

  switch (analyze_statuses[status].lr[s->observe - 1]) {
    case 1:
      failed = 1;
      break;

    case 2:
      failed = 0;
      break;

    default:
      return;
  }

  if (!failed) {
    /* good: clear consecutive_errors */
    HA_ATOMIC_STORE(&s->consecutive_errors, 0);
    return;
  }

  if (HA_ATOMIC_ADD_FETCH(&s->consecutive_errors, 1) < s->consecutive_errors_limit)
    return;

  chunk_printf(&trash, "Detected %d consecutive errors, last one was: %s",
               HA_ATOMIC_LOAD(&s->consecutive_errors), get_analyze_status(status));

  HA_SPIN_LOCK(SERVER_LOCK, &s->lock);

  /* force fastinter for upcoming check
   * (does nothing if fastinter is not enabled)
   */
  s->check.state |= CHK_ST_FASTINTER;

  switch (s->onerror) {
    case HANA_ONERR_FASTINTER:
    /* force fastinter - nothing to do here as all modes force it */
      break;

    case HANA_ONERR_SUDDTH:
    /* simulate a pre-fatal failed health check */
      if (s->check.health > s->check.rise)
        s->check.health = s->check.rise + 1;

      __fallthrough;

    case HANA_ONERR_FAILCHK:
    /* simulate a failed health check */
      set_server_check_status(&s->check, HCHK_STATUS_HANA,
            trash.area);
      check_notify_failure(&s->check);
      break;

    case HANA_ONERR_MARKDWN:
    /* mark server down */
      s->check.health = s->check.rise;
      set_server_check_status(&s->check, HCHK_STATUS_HANA,
            trash.area);
      check_notify_failure(&s->check);
      break;

    default:
      /* write a warning? */
      break;
  }

  HA_SPIN_UNLOCK(SERVER_LOCK, &s->lock);

  HA_ATOMIC_STORE(&s->consecutive_errors, 0);
  if (s->counters.shared.tg[tgid - 1])
    _HA_ATOMIC_INC(&s->counters.shared.tg[tgid - 1]->failed_hana);

  if (s->check.fastinter) {
    /* timer might need to be advanced, it might also already be
     * running in another thread. Let's just wake the task up, it
     * will automatically adjust its timer.
     */
    task_wakeup(s->check.task, TASK_WOKEN_MSG);
  }
}

/* Checks the connection. If an error has already been reported or the socket is
 * closed, keep errno intact as it is supposed to contain the valid error code.
 * If no error is reported, check the socket's error queue using getsockopt().
 * Warning, this must be done only once when returning from poll, and never
 * after an I/O error was attempted, otherwise the error queue might contain
 * inconsistent errors. If an error is detected, the CO_FL_ERROR is set on the
 * socket. Returns non-zero if an error was reported, zero if everything is
 * clean (including a properly closed socket).
 */
static int retrieve_errno_from_socket(struct connection *conn)
{
  int skerr;
  socklen_t lskerr = sizeof(skerr);

  if (conn->flags & CO_FL_ERROR && (unclean_errno(errno) || !conn->ctrl))
    return 1;

  if (!conn_ctrl_ready(conn))
    return 0;

  BUG_ON(conn->flags & CO_FL_FDLESS);

  if (getsockopt(conn->handle.fd, SOL_SOCKET, SO_ERROR, &skerr, &lskerr) == 0)
    errno = skerr;

  errno = unclean_errno(errno);

  if (!errno) {
    /* we could not retrieve an error, that does not mean there is
     * none. Just don't change anything and only report the prior
     * error if any.
     */
    if (conn->flags & CO_FL_ERROR)
      return 1;
    else
      return 0;
  }

  conn->flags |= CO_FL_ERROR | CO_FL_SOCK_WR_SH | CO_FL_SOCK_RD_SH;
  return 1;
}

/* Tries to collect as much information as possible on the connection status,
 * and adjust the server status accordingly. It may make use of <errno_bck>
 * if non-null when the caller is absolutely certain of its validity (eg:
 * checked just after a syscall). If the caller doesn't have a valid errno,
 * it can pass zero, and retrieve_errno_from_socket() will be called to try
 * to extract errno from the socket. If no error is reported, it will consider
 * the <expired> flag. This is intended to be used when a connection error was
 * reported in conn->flags or when a timeout was reported in <expired>. The
 * function takes care of not updating a server status which was already set.
 * All situations where at least one of <expired> or CO_FL_ERROR are set
 * produce a status.
 */
void chk_report_conn_err(struct check *check, int errno_bck, int expired)
{
  struct stconn *sc = check->sc;
  struct connection *conn = sc_conn(sc);
  const char *err_msg;
  struct buffer *chk;
  int step;

  if (check->result != CHK_RES_UNKNOWN) {
    return;
  }

  errno = unclean_errno(errno_bck);
  if (conn && errno)
    retrieve_errno_from_socket(conn);

  TRACE_ENTER(CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check, 0, 0, (size_t[]){expired});

  /* we'll try to build a meaningful error message depending on the
   * context of the error possibly present in conn->err_code, and the
   * socket error possibly collected above. This is useful to know the
   * exact step of the L6 layer (eg: SSL handshake).
   */
  chk = get_trash_chunk();

  if (check->type == PR_O2_TCPCHK_CHK &&
      (check->tcpcheck_rules->flags & TCPCHK_RULES_PROTO_CHK) == TCPCHK_RULES_TCP_CHK) {
    step = tcpcheck_get_step_id(check, NULL);
    if (!step) {
      TRACE_DEVEL("initial connection failure", CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
      chunk_printf(chk, " at initial connection step of tcp-check");
    }
    else {
      chunk_printf(chk, " at step %d of tcp-check", step);
      /* we were looking for a string */
      if (check->current_step && check->current_step->action == TCPCHK_ACT_CONNECT) {
        if (check->current_step->connect.port)
          chunk_appendf(chk, " (connect port %d)" ,check->current_step->connect.port);
        else
          chunk_appendf(chk, " (connect)");
        TRACE_DEVEL("connection failure", CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
      }
      else if (check->current_step && check->current_step->action == TCPCHK_ACT_EXPECT) {
        struct tcpcheck_expect *expect = &check->current_step->expect;

        switch (expect->type) {
        case TCPCHK_EXPECT_STRING:
          chunk_appendf(chk, " (expect string '%.*s')", (unsigned int)istlen(expect->data), istptr(expect->data));
          break;
        case TCPCHK_EXPECT_BINARY:
          chunk_appendf(chk, " (expect binary '");
          dump_binary(chk, istptr(expect->data), (int)istlen(expect->data));
          chunk_appendf(chk, "')");
          break;
        case TCPCHK_EXPECT_STRING_REGEX:
          chunk_appendf(chk, " (expect regex)");
          break;
        case TCPCHK_EXPECT_BINARY_REGEX:
          chunk_appendf(chk, " (expect binary regex)");
          break;
        case TCPCHK_EXPECT_STRING_LF:
          chunk_appendf(chk, " (expect log-format string)");
          break;
        case TCPCHK_EXPECT_BINARY_LF:
          chunk_appendf(chk, " (expect log-format binary)");
          break;
        case TCPCHK_EXPECT_HTTP_STATUS:
          chunk_appendf(chk, " (expect HTTP status codes)");
          break;
        case TCPCHK_EXPECT_HTTP_STATUS_REGEX:
          chunk_appendf(chk, " (expect HTTP status regex)");
          break;
        case TCPCHK_EXPECT_HTTP_HEADER:
          chunk_appendf(chk, " (expect HTTP header pattern)");
          break;
        case TCPCHK_EXPECT_HTTP_BODY:
          chunk_appendf(chk, " (expect HTTP body content '%.*s')", (unsigned int)istlen(expect->data), istptr(expect->data));
          break;
        case TCPCHK_EXPECT_HTTP_BODY_REGEX:
          chunk_appendf(chk, " (expect HTTP body regex)");
          break;
        case TCPCHK_EXPECT_HTTP_BODY_LF:
          chunk_appendf(chk, " (expect log-format HTTP body)");
          break;
        case TCPCHK_EXPECT_CUSTOM:
          chunk_appendf(chk, " (expect custom function)");
          break;
        case TCPCHK_EXPECT_UNDEF:
          chunk_appendf(chk, " (undefined expect!)");
          break;
        }
        TRACE_DEVEL("expect rule failed", CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
      }
      else if (check->current_step && check->current_step->action == TCPCHK_ACT_SEND) {
        chunk_appendf(chk, " (send)");
        TRACE_DEVEL("send rule failed", CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
      }

      if (check->current_step && check->current_step->comment)
        chunk_appendf(chk, " comment: '%s'", check->current_step->comment);
    }
  }

  if (conn && conn->err_code) {
    if (unclean_errno(errno))
      chunk_printf(&trash, "%s (%s)%s", conn_err_code_str(conn), strerror(errno),
             chk->area);
    else
      chunk_printf(&trash, "%s%s", conn_err_code_str(conn),
             chk->area);
    err_msg = trash.area;
  }
  else {
    if (unclean_errno(errno)) {
      chunk_printf(&trash, "%s%s", strerror(errno),
             chk->area);
      err_msg = trash.area;
    }
    else {
      err_msg = chk->area;
    }
  }

  if (check->state & CHK_ST_PORT_MISS) {
    /* NOTE: this is reported after <fall> tries */
    set_server_check_status(check, HCHK_STATUS_SOCKERR, err_msg);
  }

  if (!conn || !conn->ctrl) {
    /* error before any connection attempt (connection allocation error or no control layer) */
    set_server_check_status(check, HCHK_STATUS_SOCKERR, err_msg);
  }
  else if (conn->flags & CO_FL_WAIT_L4_CONN) {
    /* L4 not established (yet) */
    if (conn->flags & CO_FL_ERROR || sc_ep_test(sc, SE_FL_ERROR))
      set_server_check_status(check, HCHK_STATUS_L4CON, err_msg);
    else if (expired)
      set_server_check_status(check, HCHK_STATUS_L4TOUT, err_msg);

    /*
     * might be due to a server IP change.
     * Let's trigger a DNS resolution if none are currently running.
     */
    if (check->server)
      resolv_trigger_resolution(check->server->resolv_requester);

  }
  else if (conn->flags & CO_FL_WAIT_L6_CONN) {
    /* L6 not established (yet) */
    if (conn->flags & CO_FL_ERROR || sc_ep_test(sc, SE_FL_ERROR))
      set_server_check_status(check, HCHK_STATUS_L6RSP, err_msg);
    else if (expired)
      set_server_check_status(check, HCHK_STATUS_L6TOUT, err_msg);
  }
  else if (conn->flags & CO_FL_ERROR || sc_ep_test(sc, SE_FL_ERROR)) {
    /* I/O error after connection was established and before we could diagnose */
    set_server_check_status(check, HCHK_STATUS_SOCKERR, err_msg);
  }
  else if (expired) {
    enum healthcheck_status tout = HCHK_STATUS_L7TOUT;

    /* connection established but expired check */
    if (check->current_step && check->current_step->action == TCPCHK_ACT_EXPECT &&
        check->current_step->expect.tout_status != HCHK_STATUS_UNKNOWN)
      tout = check->current_step->expect.tout_status;
    set_server_check_status(check, tout, err_msg);
  }

  if (check->result == CHK_RES_UNKNOWN) {
    /* No other reason found, report a socket error (may be an internal or a ressournce error) */
    set_server_check_status(check, HCHK_STATUS_SOCKERR, err_msg);
  }

  TRACE_LEAVE(CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
  return;
}


/* Builds the server state header used by HTTP health-checks */
int httpchk_build_status_header(struct server *s, struct buffer *buf)
{
  int sv_state;
  int ratio;
  char addr[46];
  char port[6];
  const char *srv_hlt_st[7] = { "DOWN", "DOWN %d/%d",
              "UP %d/%d", "UP",
              "NOLB %d/%d", "NOLB",
              "no check" };
  unsigned long last_change = s->last_change;

  if (!(s->check.state & CHK_ST_ENABLED))
    sv_state = 6;
  else if (s->cur_state != SRV_ST_STOPPED) {
    if (s->check.health == s->check.rise + s->check.fall - 1)
      sv_state = 3; /* UP */
    else
      sv_state = 2; /* going down */

    if (s->cur_state == SRV_ST_STOPPING)
      sv_state += 2;
  } else {
    if (s->check.health)
      sv_state = 1; /* going up */
    else
      sv_state = 0; /* DOWN */
  }

  chunk_appendf(buf, srv_hlt_st[sv_state],
          (s->cur_state != SRV_ST_STOPPED) ? (s->check.health - s->check.rise + 1) : (s->check.health),
          (s->cur_state != SRV_ST_STOPPED) ? (s->check.fall) : (s->check.rise));

  addr_to_str(&s->addr, addr, sizeof(addr));
  if (s->addr.ss_family == AF_INET || s->addr.ss_family == AF_INET6)
    snprintf(port, sizeof(port), "%u", s->svc_port);
  else
    *port = 0;

  chunk_appendf(buf, "; address=%s; port=%s; name=%s/%s; node=%s; weight=%d/%d; scur=%d/%d; qcur=%d",
          addr, port, s->proxy->id, s->id,
          global.node,
          (s->cur_eweight * s->proxy->lbprm.wmult + s->proxy->lbprm.wdiv - 1) / s->proxy->lbprm.wdiv,
          (s->proxy->lbprm.tot_weight * s->proxy->lbprm.wmult + s->proxy->lbprm.wdiv - 1) / s->proxy->lbprm.wdiv,
          s->cur_sess, s->proxy->beconn - s->proxy->queueslength,
          s->queueslength);

  if ((s->cur_state == SRV_ST_STARTING) &&
      ns_to_sec(now_ns) < last_change + s->slowstart &&
      ns_to_sec(now_ns) >= last_change) {
    ratio = MAX(1, 100 * (ns_to_sec(now_ns) - last_change) / s->slowstart);
    chunk_appendf(buf, "; throttle=%d%%", ratio);
  }

  return b_data(buf);
}

/**************************************************************************/
/***************** Health-checks based on connections *********************/
/**************************************************************************/
/* This function is used only for server health-checks. It handles connection
 * status updates including errors. If necessary, it wakes the check task up.
 * It returns 0 on normal cases, <0 if at least one close() has happened on the
 * connection (eg: reconnect). It relies on tcpcheck_main().
 */
int wake_srv_chk(struct stconn *sc)
{
  struct connection *conn;
  struct check *check = __sc_check(sc);
  int ret = 0;

  BUG_ON(!check->server);

  TRACE_ENTER(CHK_EV_HCHK_WAKE, check);
  if (check->result != CHK_RES_UNKNOWN)
    goto end;

  HA_SPIN_LOCK(SERVER_LOCK, &check->server->lock);

  /* we may have to make progress on the TCP checks */
  ret = tcpcheck_main(check);

  sc = check->sc;
  conn = sc_conn(sc);

  if (unlikely(!conn || conn->flags & CO_FL_ERROR || sc_ep_test(sc, SE_FL_ERROR))) {
    /* We may get error reports bypassing the I/O handlers, typically
     * the case when sending a pure TCP check which fails, then the I/O
     * handlers above are not called. This is completely handled by the
     * main processing task so let's simply wake it up. If we get here,
     * we expect errno to still be valid.
     */
    TRACE_ERROR("report connection error", CHK_EV_HCHK_WAKE|CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
    chk_report_conn_err(check, errno, 0);
    task_wakeup(check->task, TASK_WOKEN_IO);
  }

  if (check->result != CHK_RES_UNKNOWN || ret == -1) {
    /* Check complete or aborted. Wake the check task up to be sure
     * the result is handled ASAP. */
    ret = -1;
    task_wakeup(check->task, TASK_WOKEN_IO);
  }
  else {
    /* Check in progress. Queue it to eventually handle timeout
     * update */
    task_queue(check->task);
  }

  HA_SPIN_UNLOCK(SERVER_LOCK, &check->server->lock);

  end:
  TRACE_LEAVE(CHK_EV_HCHK_WAKE, check);
  return ret;
}

/* This function checks if any I/O is wanted, and if so, attempts to do so */
struct task *srv_chk_io_cb(struct task *t, void *ctx, unsigned int state)
{
  struct stconn *sc = ctx;

  wake_srv_chk(sc);
  return t;
}

/* returns <0, 0, >0 if check thread 1 is respectively less loaded than,
 * equally as, or more loaded than thread 2. This is made to decide on
 * migrations so a margin is applied in either direction. For ease of
 * remembering the direction, consider this returns load1 - load2.
 */
static inline int check_thread_cmp_load(int thr1, int thr2)
{
  uint t1_load = _HA_ATOMIC_LOAD(&ha_thread_ctx[thr1].rq_total);
  uint t1_act  = _HA_ATOMIC_LOAD(&ha_thread_ctx[thr1].active_checks);
  uint t2_load = _HA_ATOMIC_LOAD(&ha_thread_ctx[thr2].rq_total);
  uint t2_act  = _HA_ATOMIC_LOAD(&ha_thread_ctx[thr2].active_checks);

  /* twice as more active checks is a significant difference */
  if (t1_act * 2 < t2_act)
    return -1;

  if (t2_act * 2 < t1_act)
    return 1;

  /* twice as more rqload with more checks is also a significant
   * difference.
   */
  if (t1_act <= t2_act && t1_load * 2 < t2_load)
    return -1;

  if (t2_act <= t1_act && t2_load * 2 < t1_load)
    return 1;

  /* otherwise they're roughly equal */
  return 0;
}

/* returns <0, 0, >0 if check thread 1's active checks count is respectively
 * higher than, equal, or lower than thread 2's. This is made to decide on
 * forced migrations upon overload, so only a very little margin is applied
 * here (~1%). For ease of remembering the direction, consider this returns
 * active1 - active2.
 */
static inline int check_thread_cmp_active(int thr1, int thr2)
{
  uint t1_act  = _HA_ATOMIC_LOAD(&ha_thread_ctx[thr1].active_checks);
  uint t2_act  = _HA_ATOMIC_LOAD(&ha_thread_ctx[thr2].active_checks);

  if (t1_act * 128 >= t2_act * 129)
    return 1;
  if (t2_act * 128 >= t1_act * 129)
    return -1;
  return 0;
}


/* manages a server health-check that uses a connection. Returns
 * the time the task accepts to wait, or TIME_ETERNITY for infinity.
 *
 * Please do NOT place any return statement in this function and only leave
 * via the out_unlock label.
 */
struct task *process_chk_conn(struct task *t, void *context, unsigned int state)
{
  struct check *check = context;
  struct proxy *proxy = check->proxy;
  struct stconn *sc;
  struct connection *conn;
  int rv;
  int expired = tick_is_expired(t->expire, now_ms);

  TRACE_ENTER(CHK_EV_TASK_WAKE, check);

  if (check->state & CHK_ST_SLEEPING) {
    /* This check just restarted. It's still time to verify if
     * we're on an overloaded thread or if a more suitable one is
     * available. This helps spread the load over the available
     * threads, without migrating too often. For this we'll check
     * our load, and pick a random thread, check if it has less
     * than half of the current thread's load, and if so we'll
     * bounce the task there. It's possible because it's not yet
     * tied to the current thread. The other thread will not bounce
     * the task again because we're setting CHK_ST_READY indicating
     * a migration.
     */
    uint run_checks = _HA_ATOMIC_LOAD(&th_ctx->running_checks);
    uint my_load = HA_ATOMIC_LOAD(&th_ctx->rq_total);
    uint attempts = MIN(global.nbthread, 3);

    if (check->state & CHK_ST_READY) {
      /* check was migrated, active already counted */
      activity[tid].check_adopted++;
    }
    else {
      /* first wakeup, let's check if another thread is less loaded
       * than this one in order to smooth the load. If the current
       * thread is not yet overloaded, we attempt an opportunistic
       * migration to another thread that is not full and that is
       * significantly less loaded. And if the current thread is
       * already overloaded, we attempt a forced migration to a
       * thread with less active checks. We try at most 3 random
       * other thread.
       */
      while (attempts-- > 0 &&
             (!LIST_ISEMPTY(&th_ctx->queued_checks) || my_load >= 3) &&
             _HA_ATOMIC_LOAD(&th_ctx->active_checks) >= 3) {
        uint new_tid  = statistical_prng_range(global.nbthread);

        if (new_tid == tid)
          continue;

        ALREADY_CHECKED(new_tid);

        if (check_thread_cmp_active(tid, new_tid) > 0 &&
            (run_checks >= global.tune.max_checks_per_thread ||
             check_thread_cmp_load(tid, new_tid) > 0)) {
          /* Found one. Let's migrate the task over there. We have to
           * remove it from the WQ first and kill its expire time
           * otherwise the scheduler will reinsert it and trigger a
           * BUG_ON() as we're not allowed to call task_queue() for a
           * foreign thread. The recipient will restore the expiration.
           */
          check->state |= CHK_ST_READY;
          HA_ATOMIC_INC(&ha_thread_ctx[new_tid].active_checks);
          task_unlink_wq(t);
          t->expire = TICK_ETERNITY;
          task_set_thread(t, new_tid);
          task_wakeup(t, TASK_WOKEN_MSG);
          TRACE_LEAVE(CHK_EV_TASK_WAKE, check);
          return t;
        }
      }
      /* check just woke up, count it as active */
      _HA_ATOMIC_INC(&th_ctx->active_checks);
    }

    /* OK we're keeping it so this check is ours now */
    task_set_thread(t, tid);
    check->state &= ~CHK_ST_SLEEPING;

    /* if we just woke up and the thread is full of running, or
     * already has others waiting, we might have to wait in queue
     * (for health checks only). This means !SLEEPING && !READY.
     */
    if (check->server &&
        (!LIST_ISEMPTY(&th_ctx->queued_checks) ||
         (global.tune.max_checks_per_thread &&
          _HA_ATOMIC_LOAD(&th_ctx->running_checks) >= global.tune.max_checks_per_thread))) {
      TRACE_DEVEL("health-check queued", CHK_EV_TASK_WAKE, check);
      t->expire = TICK_ETERNITY;
      LIST_APPEND(&th_ctx->queued_checks, &check->check_queue);

      /* reset fastinter flag (if set) so that srv_getinter()
       * only returns fastinter if server health is degraded
       */
      check->state &= ~CHK_ST_FASTINTER;
      goto out_leave;
    }

    /* OK let's run, now we cannot roll back anymore */
    check->state |= CHK_ST_READY;
    activity[tid].check_started++;
    _HA_ATOMIC_INC(&th_ctx->running_checks);
  }

  /* at this point, CHK_ST_SLEEPING = 0 and CHK_ST_READY = 1*/

  if (check->server)
    HA_SPIN_LOCK(SERVER_LOCK, &check->server->lock);

  if (!(check->state & (CHK_ST_INPROGRESS|CHK_ST_IN_ALLOC|CHK_ST_OUT_ALLOC))) {
    /* This task might have bounced from another overloaded thread, it
     * needs an expiration timer that was supposed to be now, but that
     * was erased during the bounce.
     */
    if (!tick_isset(t->expire)) {
      t->expire = tick_add(now_ms, 0);
      expired = 0;
    }
  }

  if (unlikely(check->state & CHK_ST_PURGE)) {
    TRACE_STATE("health-check state to purge", CHK_EV_TASK_WAKE, check);
  }
  else if (!(check->state & (CHK_ST_INPROGRESS))) {
    /* no check currently running, but we might have been woken up
     * before the timer's expiration to update it according to a
     * new state (e.g. fastinter), in which case we'll reprogram
     * the new timer.
     */
    if (!tick_is_expired(t->expire, now_ms)) { /* woke up too early */
      if (check->server) {
        int new_exp = tick_add(now_ms, MS_TO_TICKS(srv_getinter(check)));

        if (tick_is_expired(new_exp, t->expire)) {
          TRACE_STATE("health-check was advanced", CHK_EV_TASK_WAKE, check);
          goto update_timer;
        }
      }

      TRACE_STATE("health-check wake up too early", CHK_EV_TASK_WAKE, check);
      goto out_unlock;
    }

    /* we don't send any health-checks when the proxy is
     * stopped, the server should not be checked or the check
     * is disabled.
     */
    if (((check->state & (CHK_ST_ENABLED | CHK_ST_PAUSED)) != CHK_ST_ENABLED) ||
        (proxy->flags & (PR_FL_DISABLED|PR_FL_STOPPED))) {
      TRACE_STATE("health-check paused or disabled", CHK_EV_TASK_WAKE, check);
      goto reschedule;
    }

    /* we'll initiate a new check */
    set_server_check_status(check, HCHK_STATUS_START, NULL);

    check->state |= CHK_ST_INPROGRESS;
    TRACE_STATE("init new health-check", CHK_EV_TASK_WAKE|CHK_EV_HCHK_START, check);

    check->current_step = NULL;

    check->sc = sc_new_from_check(check, SC_FL_NONE);
    if (!check->sc) {
      set_server_check_status(check, HCHK_STATUS_SOCKERR, NULL);
      goto end;
    }
    tcpcheck_main(check);
    expired = 0;
  }

  /* there was a test running.
   * First, let's check whether there was an uncaught error,
   * which can happen on connect timeout or error.
   */
  if (check->result == CHK_RES_UNKNOWN && likely(!(check->state & CHK_ST_PURGE))) {
    sc = check->sc;
    conn = sc_conn(sc);

    /* Here the connection must be defined. Otherwise the
     * error would have already been detected
     */
    if ((conn && ((conn->flags & CO_FL_ERROR) || sc_ep_test(sc, SE_FL_ERROR))) || expired) {
      TRACE_ERROR("report connection error", CHK_EV_TASK_WAKE|CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
      chk_report_conn_err(check, 0, expired);
    }
    else {
      if (check->state & CHK_ST_CLOSE_CONN) {
        TRACE_DEVEL("closing current connection", CHK_EV_TASK_WAKE|CHK_EV_HCHK_RUN, check);
        check->state &= ~CHK_ST_CLOSE_CONN;
        if (!sc_reset_endp(check->sc)) {
          /* error will be handled by tcpcheck_main().
           * On success, remove all flags except SE_FL_DETACHED
           */
          sc_ep_clr(check->sc, ~SE_FL_DETACHED);
        }
        tcpcheck_main(check);
      }
      if (check->result == CHK_RES_UNKNOWN) {
        TRACE_DEVEL("health-check not expired", CHK_EV_TASK_WAKE|CHK_EV_HCHK_RUN, check);
        goto out_unlock; /* timeout not reached, wait again */
      }
    }
  }

  /* check complete or aborted */
  TRACE_STATE("health-check complete or aborted", CHK_EV_TASK_WAKE|CHK_EV_HCHK_END, check);

  /* check->sc may be NULL when the healthcheck is purged */
  check->current_step = NULL;
  sc = check->sc;
  conn = (sc ? sc_conn(sc) : NULL);

  if (conn && conn->xprt) {
    /* The check was aborted and the connection was not yet closed.
     * This can happen upon timeout, or when an external event such
     * as a failed response coupled with "observe layer7" caused the
     * server state to be suddenly changed.
     */
    se_shutdown(sc->sedesc, SE_SHR_DRAIN|SE_SHW_SILENT);
  }

  if (sc) {
    sc_destroy(sc);
    check->sc = NULL;
  }

  if (check->sess != NULL) {
    vars_prune(&check->vars, check->sess, NULL);
    session_free(check->sess);
    check->sess = NULL;
  }

  end:
  if (check->server && likely(!(check->state & CHK_ST_PURGE))) {
    if (check->result == CHK_RES_FAILED) {
      /* a failure or timeout detected */
      TRACE_DEVEL("report failure", CHK_EV_TASK_WAKE|CHK_EV_HCHK_END|CHK_EV_HCHK_ERR, check);
      check_notify_failure(check);
    }
    else if (check->result == CHK_RES_CONDPASS) {
      /* check is OK but asks for stopping mode */
      TRACE_DEVEL("report conditional success", CHK_EV_TASK_WAKE|CHK_EV_HCHK_END|CHK_EV_HCHK_SUCC, check);
      check_notify_stopping(check);
    }
    else if (check->result == CHK_RES_PASSED) {
      /* a success was detected */
      TRACE_DEVEL("report success", CHK_EV_TASK_WAKE|CHK_EV_HCHK_END|CHK_EV_HCHK_SUCC, check);
      check_notify_success(check);
    }
  }

  b_dequeue(&check->buf_wait);

  check_release_buf(check, &check->bi);
  check_release_buf(check, &check->bo);
  _HA_ATOMIC_DEC(&th_ctx->running_checks);
  _HA_ATOMIC_DEC(&th_ctx->active_checks);
  check->state &= ~(CHK_ST_INPROGRESS|CHK_ST_IN_ALLOC|CHK_ST_OUT_ALLOC);
  check->state &= ~CHK_ST_READY;
  check->state |= CHK_ST_SLEEPING;

 update_timer:
  /* when going to sleep, we need to check if other checks are waiting
   * for a slot. If so we pick them out of the queue and wake them up.
   */
  if (check->server && (check->state & CHK_ST_SLEEPING)) {
    if (!LIST_ISEMPTY(&th_ctx->queued_checks) &&
        _HA_ATOMIC_LOAD(&th_ctx->running_checks) < global.tune.max_checks_per_thread) {
      struct check *next_chk = LIST_ELEM(th_ctx->queued_checks.n, struct check *, check_queue);

      /* wake up pending task */
      LIST_DEL_INIT(&next_chk->check_queue);

      activity[tid].check_started++;
      _HA_ATOMIC_INC(&th_ctx->running_checks);
      next_chk->state |= CHK_ST_READY;
      /* now running */
      task_wakeup(next_chk->task, TASK_WOKEN_RES);
    }
  }

  if (check->server) {
    rv = 0;
    if (global.spread_checks > 0) {
      rv = srv_getinter(check) * global.spread_checks / 100;
      rv -= (int) (2 * rv * (statistical_prng() / 4294967295.0));
    }
    t->expire = tick_add(now_ms, MS_TO_TICKS(srv_getinter(check) + rv));
    /* reset fastinter flag (if set) so that srv_getinter()
     * only returns fastinter if server health is degraded
     */
    check->state &= ~CHK_ST_FASTINTER;
  }

 reschedule:
  if (proxy->flags & (PR_FL_DISABLED|PR_FL_STOPPED))
    t->expire = TICK_ETERNITY;
  else {
    while (tick_is_expired(t->expire, now_ms))
      t->expire = tick_add(t->expire, MS_TO_TICKS(check->inter));
  }

 out_unlock:
  if (check->server)
    HA_SPIN_UNLOCK(SERVER_LOCK, &check->server->lock);

 out_leave:
  TRACE_LEAVE(CHK_EV_TASK_WAKE, check);

  /* Free the check if set to PURGE. After this, the check instance may be
   * freed via the srv_drop invocation, so it must not be accessed after
   * this point.
   */
  if (unlikely(check->state & CHK_ST_PURGE)) {
    free_check(check);
    if (check->server)
      srv_drop(check->server);

    t = NULL;
  }

  return t;
}


/**************************************************************************/
/************************** Init/deinit checks ****************************/
/**************************************************************************/
/*
 * Tries to grab a buffer and to re-enables processing on check <target>. The
 * check flags are used to figure what buffer was requested. It returns 1 if the
 * allocation succeeds, in which case the I/O tasklet is woken up, or 0 if it's
 * impossible to wake up and we prefer to be woken up later.
 */
int check_buf_available(void *target)
{
  struct check *check = target;

  BUG_ON(!check->sc);

  if ((check->state & CHK_ST_IN_ALLOC) && b_alloc(&check->bi, DB_CHANNEL)) {
    TRACE_STATE("unblocking check, input buffer allocated", CHK_EV_TCPCHK_EXP|CHK_EV_RX_BLK, check);
    check->state &= ~CHK_ST_IN_ALLOC;
    tasklet_wakeup(check->sc->wait_event.tasklet);
    return 1;
  }
  if ((check->state & CHK_ST_OUT_ALLOC) && b_alloc(&check->bo, DB_CHANNEL)) {
    TRACE_STATE("unblocking check, output buffer allocated", CHK_EV_TCPCHK_SND|CHK_EV_TX_BLK, check);
    check->state &= ~CHK_ST_OUT_ALLOC;
    tasklet_wakeup(check->sc->wait_event.tasklet);
    return 1;
  }

  return 0;
}

/*
 * Allocate a buffer. If it fails, it adds the check in buffer wait queue.
 */
struct buffer *check_get_buf(struct check *check, struct buffer *bptr)
{
  struct buffer *buf = NULL;

  if (likely(!LIST_INLIST(&check->buf_wait.list)) &&
      unlikely((buf = b_alloc(bptr, DB_CHANNEL)) == NULL)) {
    b_queue(DB_CHANNEL, &check->buf_wait, check, check_buf_available);
  }
  return buf;
}

/*
 * Release a buffer, if any, and try to wake up entities waiting in the buffer
 * wait queue.
 */
void check_release_buf(struct check *check, struct buffer *bptr)
{
  if (bptr->size) {
    b_free(bptr);
    offer_buffers(check->buf_wait.target, 1);
  }
}

const char *init_check(struct check *check, int type)
{
  check->type = type;

  check->bi = BUF_NULL;
  check->bo = BUF_NULL;
  LIST_INIT(&check->buf_wait.list);
  LIST_INIT(&check->check_queue);
  return NULL;
}

/* Liberates the resources allocated for a check.
 *
 * This function must only be run by the thread owning the check.
 */
void free_check(struct check *check)
{
  /* For agent-check, free the rules / vars from the server. This is not
   * done for health-check : the proxy is the owner of the rules / vars
   * in this case.
   */
  if (check->state & CHK_ST_AGENT) {
    free_tcpcheck_vars(&check->tcpcheck_rules->preset_vars);
    ha_free(&check->tcpcheck_rules);
  }

  ha_free(&check->pool_conn_name);
  ha_free(&check->sni);
  ha_free(&check->alpn_str);
  task_destroy(check->task);

  check_release_buf(check, &check->bi);
  check_release_buf(check, &check->bo);
  if (check->sc) {
    sc_destroy(check->sc);
    check->sc = NULL;
  }
}

/* This function must be used in order to free a started check. The check will
 * be scheduled for a next execution in order to properly close and free all
 * check elements.
 *
 * Non thread-safe.
 */
void check_purge(struct check *check)
{
  check->state |= CHK_ST_PURGE;
  task_wakeup(check->task, TASK_WOKEN_OTHER);
}

/* manages a server health-check. Returns the time the task accepts to wait, or
 * TIME_ETERNITY for infinity.
 */
struct task *process_chk(struct task *t, void *context, unsigned int state)
{
  struct check *check = context;

  if (check->type == PR_O2_EXT_CHK)
    return process_chk_proc(t, context, state);
  return process_chk_conn(t, context, state);

}


int start_check_task(struct check *check, int mininter,
          int nbcheck, int srvpos)
{
  struct task *t;

  /* task for the check. Process-based checks exclusively run on thread 1. */
  if (check->type == PR_O2_EXT_CHK)
    t = task_new_on(0);
  else
    t = task_new_anywhere();

  if (!t)
    goto fail_alloc_task;

  check->task = t;
  t->process = process_chk;
  t->context = check;

  if (mininter < srv_getinter(check))
    mininter = srv_getinter(check);

  if (global.spread_checks > 0) {
    int rnd;

    rnd  = srv_getinter(check) * global.spread_checks / 100;
    rnd -= (int) (2 * rnd * (ha_random32() / 4294967295.0));
    mininter += rnd;
  }

  if (global.max_spread_checks && mininter > global.max_spread_checks)
    mininter = global.max_spread_checks;

  /* check this every ms */
  t->expire = tick_add(now_ms, MS_TO_TICKS(mininter * srvpos / nbcheck));
  check->start = now_ns;
  task_queue(t);

  return 1;

  fail_alloc_task:
  ha_alert("Starting [%s:%s] check: out of memory.\n",
     check->server->proxy->id, check->server->id);
  return 0;
}

/*
 * Start health-check.
 * Returns 0 if OK, ERR_FATAL on error, and prints the error in this case.
 */
static int start_checks()
{

  struct proxy *px;
  struct server *s;
  char *errmsg = NULL;
  int nbcheck=0, mininter=0, srvpos=0;

  /* 0- init the dummy frontend used to create all checks sessions */
  if (!setup_new_proxy(&checks_fe, "CHECKS-FE", PR_CAP_FE | PR_CAP_BE | PR_CAP_INT, &errmsg)) {
    ha_alert("error during checks frontend creation: %s\n", errmsg);
    ha_free(&errmsg);
    return ERR_ALERT | ERR_FATAL;
  }
        checks_fe.mode = PR_MODE_TCP;
  checks_fe.maxconn = 0;
  checks_fe.conn_retries = CONN_RETRIES;
  checks_fe.options2 |= PR_O2_INDEPSTR | PR_O2_SMARTCON | PR_O2_SMARTACC;
  checks_fe.timeout.client = TICK_ETERNITY;

  /* 1- count the checkers to run simultaneously.
   * We also determine the minimum interval among all of those which
   * have an interval larger than SRV_CHK_INTER_THRES. This interval
   * will be used to spread their start-up date. Those which have
   * a shorter interval will start independently and will not dictate
   * too short an interval for all others.
   */
  for (px = proxies_list; px; px = px->next) {
    for (s = px->srv; s; s = s->next) {
      if (s->check.state & CHK_ST_CONFIGURED) {
        nbcheck++;
        if ((srv_getinter(&s->check) >= SRV_CHK_INTER_THRES) &&
            (!mininter || mininter > srv_getinter(&s->check)))
          mininter = srv_getinter(&s->check);
      }

      if (s->agent.state & CHK_ST_CONFIGURED) {
        nbcheck++;
        if ((srv_getinter(&s->agent) >= SRV_CHK_INTER_THRES) &&
            (!mininter || mininter > srv_getinter(&s->agent)))
          mininter = srv_getinter(&s->agent);
      }
    }
  }

  if (!nbcheck)
    return ERR_NONE;

  srand((unsigned)time(NULL));

  /* 2- start them as far as possible from each other. For this, we will
   * start them after their interval is set to the min interval divided
   * by the number of servers, weighted by the server's position in the
   * list.
   */
  for (px = proxies_list; px; px = px->next) {
    if ((px->options2 & PR_O2_CHK_ANY) == PR_O2_EXT_CHK) {
      if (init_pid_list()) {
        ha_alert("Starting [%s] check: out of memory.\n", px->id);
        return ERR_ALERT | ERR_FATAL;
      }
    }

    for (s = px->srv; s; s = s->next) {
      /* A task for the main check */
      if (s->check.state & CHK_ST_CONFIGURED) {
        if (s->check.type == PR_O2_EXT_CHK) {
          if (!prepare_external_check(&s->check))
            return ERR_ALERT | ERR_FATAL;
        }
        if (!start_check_task(&s->check, mininter, nbcheck, srvpos))
          return ERR_ALERT | ERR_FATAL;
        srvpos++;
      }

      /* A task for a auxiliary agent check */
      if (s->agent.state & CHK_ST_CONFIGURED) {
        if (!start_check_task(&s->agent, mininter, nbcheck, srvpos)) {
          return ERR_ALERT | ERR_FATAL;
        }
        srvpos++;
      }
    }
  }
  return ERR_NONE;
}

/* called during deinit */
static void clear_checks()
{
  if (checks_fe.id)
    deinit_proxy(&checks_fe);
}

/*
 * Return value:
 *   the port to be used for the health check
 *   0 in case no port could be found for the check
 */
static int srv_check_healthcheck_port(struct check *chk)
{
  int i = 0;
  struct server *srv = NULL;

  srv = chk->server;

  /* by default, we use the health check port configured */
  if (chk->port > 0)
    return chk->port;

  /* try to get the port from check_core.addr if check.port not set */
  i = get_host_port(&chk->addr);
  if (i > 0)
    return i;

  /* try to get the port from server address */
  /* prevent MAPPORTS from working at this point, since checks could
   * not be performed in such case (MAPPORTS impose a relative ports
   * based on live traffic)
   */
  if (srv->flags & SRV_F_MAPPORTS)
    return 0;

  i = srv->svc_port; /* by default */
  if (i > 0)
    return i;

  return 0;
}

/* Initializes an health-check attached to the server <srv>. Non-zero is returned
 * if an error occurred.
 */
int init_srv_check(struct server *srv)
{
  const char *err;
  struct tcpcheck_rule *r;
  int ret = ERR_NONE;
  int check_type;

  if (!srv->do_check || !(srv->proxy->cap & PR_CAP_BE))
    goto out;

  check_type = srv->check.tcpcheck_rules->flags & TCPCHK_RULES_PROTO_CHK;

  if (!(srv->flags & SRV_F_DYNAMIC)) {
    /* If neither a port nor an addr was specified and no check
     * transport layer is forced, then the transport layer used by
     * the checks is the same as for the production traffic.
     * Otherwise we use raw_sock by default, unless one is
     * specified.
     */
    if (!srv->check.port && !is_addr(&srv->check.addr)) {
      if (!srv->check.use_ssl && srv->use_ssl != -1)
        srv->check.xprt = srv->xprt;
      else if (srv->check.use_ssl == 1)
        srv->check.xprt = xprt_get(XPRT_SSL);
      srv->check.send_proxy |= (srv->pp_opts);
    }
    else if (srv->check.use_ssl == 1)
      srv->check.xprt = xprt_get(XPRT_SSL);
  }
  else {
    /* For dynamic servers, check-ssl and check-send-proxy must be
     * explicitly defined even if the check port was not
     * overridden.
     */
    if (srv->check.use_ssl == 1)
      srv->check.xprt = xprt_get(XPRT_SSL);
  }

  /* Inherit the mux protocol from the server if not already defined for
   * the check
   */
  if (srv->mux_proto && !srv->check.mux_proto &&
      ((srv->mux_proto->mode == PROTO_MODE_HTTP && check_type == TCPCHK_RULES_HTTP_CHK) ||
       (srv->mux_proto->mode == PROTO_MODE_SPOP && check_type == TCPCHK_RULES_SPOP_CHK) ||
       (srv->mux_proto->mode == PROTO_MODE_TCP && check_type != TCPCHK_RULES_HTTP_CHK))) {
    srv->check.mux_proto = srv->mux_proto;
  }
  /* test that check proto is valid if explicitly defined */
  else if (srv->check.mux_proto &&
           ((srv->check.mux_proto->mode == PROTO_MODE_HTTP && check_type != TCPCHK_RULES_HTTP_CHK) ||
      (srv->check.mux_proto->mode == PROTO_MODE_SPOP && check_type != TCPCHK_RULES_SPOP_CHK) ||
            (srv->check.mux_proto->mode == PROTO_MODE_TCP && check_type == TCPCHK_RULES_HTTP_CHK))) {
    ha_alert("config: %s '%s': server '%s' uses an incompatible MUX protocol for the selected check type\n",
             proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
    ret |= ERR_ALERT | ERR_FATAL;
    goto out;
  }

  /* validate <srv> server health-check settings */

  if (srv_is_quic(srv)) {
    if (srv->check.mux_proto && srv->check.mux_proto != get_mux_proto(ist("quic"))) {
      ha_alert("config: %s '%s': QUIC server '%s' uses an incompatible MUX protocol for checks.\n",
               proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
      ret |= ERR_ALERT | ERR_FATAL;
      goto out;
    }

    if (srv->check.use_ssl < 0) {
      ha_alert("config: %s '%s': SSL is mandatory for checks on QUIC server '%s'.\n",
               proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
      ret |= ERR_ALERT | ERR_FATAL;
    }

    if (srv->check.send_proxy) {
      ha_alert("config: %s '%s': cannot use PROXY protocol for checks on QUIC server '%s'.\n",
               proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
      ret |= ERR_ALERT | ERR_FATAL;
    }
  }
  else {
    if (srv->check.mux_proto && srv->check.mux_proto == get_mux_proto(ist("quic"))) {
      ha_alert("config: %s '%s': QUIC checks on non-QUIC server '%s' is not yet supported.\n",
               proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
      ret |= ERR_ALERT | ERR_FATAL;
      goto out;
    }
  }

  /* We need at least a service port, a check port or the first tcp-check
   * rule must be a 'connect' one when checking an IPv4/IPv6 server.
   */
  if ((srv_check_healthcheck_port(&srv->check) != 0) ||
      (!is_inet_addr(&srv->check.addr) && (is_addr(&srv->check.addr) || !is_inet_addr(&srv->addr))))
    goto init;

  if (!srv->proxy->tcpcheck_rules.list || LIST_ISEMPTY(srv->proxy->tcpcheck_rules.list)) {
    ha_alert("config: %s '%s': server '%s' has neither service port nor check port.\n",
       proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
    ret |= ERR_ALERT | ERR_ABORT;
    goto out;
  }

  /* search the first action (connect / send / expect) in the list */
  r = get_first_tcpcheck_rule(&srv->proxy->tcpcheck_rules);
  if (!r || (r->action != TCPCHK_ACT_CONNECT) || (!r->connect.port && !get_host_port(&r->connect.addr))) {
    ha_alert("config: %s '%s': server '%s' has neither service port nor check port "
       "nor tcp_check rule 'connect' with port information.\n",
       proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
    ret |= ERR_ALERT | ERR_ABORT;
    goto out;
  }

  /* scan the tcp-check ruleset to ensure a port has been configured */
  list_for_each_entry(r, srv->proxy->tcpcheck_rules.list, list) {
    if ((r->action == TCPCHK_ACT_CONNECT) && (!r->connect.port && !get_host_port(&r->connect.addr))) {
      ha_alert("config: %s '%s': server '%s' has neither service port nor check port, "
         "and a tcp_check rule 'connect' with no port information.\n",
         proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
      ret |= ERR_ALERT | ERR_ABORT;
      goto out;
    }
  }

  init:
  err = init_check(&srv->check, srv->proxy->options2 & PR_O2_CHK_ANY);
  if (err) {
    ha_alert("config: %s '%s': unable to init check for server '%s' (%s).\n",
       proxy_type_str(srv->proxy), srv->proxy->id, srv->id, err);
    ret |= ERR_ALERT | ERR_ABORT;
    goto out;
  }
  srv->check.state |= CHK_ST_CONFIGURED | CHK_ST_ENABLED | CHK_ST_SLEEPING;
  srv_take(srv);

  /* Only increment maxsock for servers from the configuration. Dynamic
   * servers at the moment are not taken into account for the estimation
   * of the resources limits.
   */
  if (global.mode & MODE_STARTING)
    global.maxsock++;

  out:
  return ret;
}

/* Initializes an agent-check attached to the server <srv>. Non-zero is returned
 * if an error occurred.
 */
int init_srv_agent_check(struct server *srv)
{
  struct tcpcheck_rule *chk;
  const char *err;
  int ret = ERR_NONE;

  if (!srv->do_agent || !(srv->proxy->cap & PR_CAP_BE))
    goto out;

  /* If there is no connect rule preceding all send / expect rules, an
   * implicit one is inserted before all others.
   */
  chk = get_first_tcpcheck_rule(srv->agent.tcpcheck_rules);
  if (!chk || chk->action != TCPCHK_ACT_CONNECT) {
    chk = calloc(1, sizeof(*chk));
    if (!chk) {
      ha_alert("%s '%s': unable to add implicit tcp-check connect rule"
         " to agent-check for server '%s' (out of memory).\n",
         proxy_type_str(srv->proxy), srv->proxy->id, srv->id);
      ret |= ERR_ALERT | ERR_FATAL;
      goto out;
    }
    chk->action = TCPCHK_ACT_CONNECT;
    chk->connect.options = (TCPCHK_OPT_DEFAULT_CONNECT|TCPCHK_OPT_IMPLICIT);
    LIST_INSERT(srv->agent.tcpcheck_rules->list, &chk->list);
  }

  /* <chk> is always defined here and it is a CONNECT action. If there is
   * a preset variable, it means there is an agent string defined and data
   * will be sent after the connect.
   */
  if (!LIST_ISEMPTY(&srv->agent.tcpcheck_rules->preset_vars))
    chk->connect.options |= TCPCHK_OPT_HAS_DATA;


  err = init_check(&srv->agent, PR_O2_TCPCHK_CHK);
  if (err) {
    ha_alert("config: %s '%s': unable to init agent-check for server '%s' (%s).\n",
       proxy_type_str(srv->proxy), srv->proxy->id, srv->id, err);
    ret |= ERR_ALERT | ERR_ABORT;
    goto out;
  }

  if (!srv->agent.inter)
    srv->agent.inter = srv->check.inter;

  srv->agent.state |= CHK_ST_CONFIGURED | CHK_ST_ENABLED | CHK_ST_SLEEPING | CHK_ST_AGENT;
  srv_take(srv);

  /* Only increment maxsock for servers from the configuration. Dynamic
   * servers at the moment are not taken into account for the estimation
   * of the resources limits.
   */
  if (global.mode & MODE_STARTING)
    global.maxsock++;

  out:
  return ret;
}

static void deinit_srv_check(struct server *srv)
{
  if (srv->check.state & CHK_ST_CONFIGURED) {
    free_check(&srv->check);
    /* it is safe to drop now since the main server reference is still held by the proxy */
    srv_drop(srv);
  }
  srv->check.state &= ~CHK_ST_CONFIGURED & ~CHK_ST_ENABLED;
  srv->do_check = 0;
}


static void deinit_srv_agent_check(struct server *srv)
{
  if (srv->agent.state & CHK_ST_CONFIGURED) {
    free_check(&srv->agent);
    /* it is safe to drop now since the main server reference is still held by the proxy */
    srv_drop(srv);
  }

  srv->agent.state &= ~CHK_ST_CONFIGURED & ~CHK_ST_ENABLED & ~CHK_ST_AGENT;
  srv->do_agent = 0;
}

REGISTER_POST_SERVER_CHECK(init_srv_check);
REGISTER_POST_SERVER_CHECK(init_srv_agent_check);
REGISTER_POST_CHECK(start_checks);

REGISTER_SERVER_DEINIT(deinit_srv_check);
REGISTER_SERVER_DEINIT(deinit_srv_agent_check);
REGISTER_POST_DEINIT(clear_checks);

/* perform minimal initializations */
static void init_checks()
{
  int i;

  for (i = 0; i < MAX_THREADS; i++)
    LIST_INIT(&ha_thread_ctx[i].queued_checks);
}

INITCALL0(STG_PREPARE, init_checks);

/**************************************************************************/
/************************** Check sample fetches **************************/
/**************************************************************************/

static struct sample_fetch_kw_list smp_kws = {ILH, {
  { /* END */ },
}};

INITCALL1(STG_REGISTER, sample_register_fetches, &smp_kws);


/**************************************************************************/
/************************ Check's parsing functions ***********************/
/**************************************************************************/
/* Parse the "addr" server keyword */
static int srv_parse_addr(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
        char **errmsg)
{
  struct sockaddr_storage *sk;
  int port1, port2, err_code = 0;


  if (!*args[*cur_arg+1]) {
    memprintf(errmsg, "'%s' expects <ipv4|ipv6> as argument.", args[*cur_arg]);
    goto error;
  }

  sk = str2sa_range(args[*cur_arg+1], NULL, &port1, &port2, NULL, NULL, NULL, errmsg, NULL, NULL, NULL,
                    PA_O_RESOLVE | PA_O_PORT_OK | PA_O_STREAM | PA_O_CONNECT);
  if (!sk) {
    memprintf(errmsg, "'%s' : %s", args[*cur_arg], *errmsg);
    goto error;
  }

  srv->check.addr = *sk;
  /* if agentaddr was never set, we can use addr */
  if (!(srv->flags & SRV_F_AGENTADDR))
    srv->agent.addr = *sk;

  out:
  return err_code;

 error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "agent-addr" server keyword */
static int srv_parse_agent_addr(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
        char **errmsg)
{
  struct sockaddr_storage sk;
  int err_code = 0;

  if (!*(args[*cur_arg+1])) {
    memprintf(errmsg, "'%s' expects an address as argument.", args[*cur_arg]);
    goto error;
  }
  memset(&sk, 0, sizeof(sk));
  if (str2ip(args[*cur_arg + 1], &sk) == NULL) {
    memprintf(errmsg, "parsing agent-addr failed. Check if '%s' is correct address.", args[*cur_arg+1]);
    goto error;
  }
  set_srv_agent_addr(srv, &sk);

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "agent-check" server keyword */
static int srv_parse_agent_check(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
         char **errmsg)
{
  struct tcpcheck_ruleset *rs = NULL;
  struct tcpcheck_rules *rules = srv->agent.tcpcheck_rules;
  struct tcpcheck_rule *chk;
  int err_code = 0;

  if (srv->do_agent)
    goto out;

  if (!(curpx->cap & PR_CAP_BE)) {
    memprintf(errmsg, "'%s' ignored because %s '%s' has no backend capability",
        args[*cur_arg], proxy_type_str(curpx), curpx->id);
    return ERR_WARN;
  }

  if (!rules) {
    rules = calloc(1, sizeof(*rules));
    if (!rules) {
      memprintf(errmsg, "out of memory.");
      goto error;
    }
    LIST_INIT(&rules->preset_vars);
    srv->agent.tcpcheck_rules = rules;
  }
  rules->list  = NULL;
  rules->flags = 0;

  rs = find_tcpcheck_ruleset("*agent-check");
  if (rs)
    goto ruleset_found;

  rs = create_tcpcheck_ruleset("*agent-check");
  if (rs == NULL) {
    memprintf(errmsg, "out of memory.");
    goto error;
  }

  chk = parse_tcpcheck_send((char *[]){"tcp-check", "send-lf", "%[var(check.agent_string)]", ""},
          1, curpx, &rs->rules, srv->conf.file, srv->conf.line, errmsg);
  if (!chk) {
    memprintf(errmsg, "'%s': %s", args[*cur_arg], *errmsg);
    goto error;
  }
  chk->index = 0;
  LIST_APPEND(&rs->rules, &chk->list);

  chk = parse_tcpcheck_expect((char *[]){"tcp-check", "expect", "custom", ""},
                        1, curpx, &rs->rules, TCPCHK_RULES_AGENT_CHK,
            srv->conf.file, srv->conf.line, errmsg);
  if (!chk) {
    memprintf(errmsg, "'%s': %s", args[*cur_arg], *errmsg);
    goto error;
  }
  chk->expect.custom = tcpcheck_agent_expect_reply;
  chk->index = 1;
  LIST_APPEND(&rs->rules, &chk->list);

  ruleset_found:
  rules->list = &rs->rules;
  rules->flags &= ~(TCPCHK_RULES_PROTO_CHK|TCPCHK_RULES_UNUSED_RS);
  rules->flags |= TCPCHK_RULES_AGENT_CHK;
  srv->do_agent = 1;

  out:
  return err_code;

  error:
  deinit_srv_agent_check(srv);
  free_tcpcheck_ruleset(rs);
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "agent-inter" server keyword */
static int srv_parse_agent_inter(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
         char **errmsg)
{
  const char *err = NULL;
  unsigned int delay;
  int err_code = 0;

  if (!*(args[*cur_arg+1])) {
    memprintf(errmsg, "'%s' expects a delay as argument.", args[*cur_arg]);
    goto error;
  }

  err = parse_time_err(args[*cur_arg+1], &delay, TIME_UNIT_MS);
  if (err == PARSE_TIME_OVER) {
    memprintf(errmsg, "timer overflow in argument <%s> to <%s> of server %s, maximum value is 2147483647 ms (~24.8 days).",
        args[*cur_arg+1], args[*cur_arg], srv->id);
    goto error;
  }
  else if (err == PARSE_TIME_UNDER) {
    memprintf(errmsg, "timer underflow in argument <%s> to <%s> of server %s, minimum non-null value is 1 ms.",
        args[*cur_arg+1], args[*cur_arg], srv->id);
    goto error;
  }
  else if (err) {
    memprintf(errmsg, "unexpected character '%c' in 'agent-inter' argument of server %s.",
        *err, srv->id);
    goto error;
  }
  if (delay <= 0) {
    memprintf(errmsg, "invalid value %d for argument '%s' of server %s.",
        delay, args[*cur_arg], srv->id);
    goto error;
  }
  srv->agent.inter = delay;

  if (warn_if_lower(args[*cur_arg+1], 100)) {
    memprintf(errmsg, "'%s %u' in server '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent",
              args[*cur_arg], delay, srv->id, delay);
    err_code |= ERR_WARN;
  }

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "agent-port" server keyword */
static int srv_parse_agent_port(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
        char **errmsg)
{
  int err_code = 0;

  if (!*(args[*cur_arg+1])) {
    memprintf(errmsg, "'%s' expects a port number as argument.", args[*cur_arg]);
    goto error;
  }

  /* Only increment maxsock for servers from the configuration. Dynamic
   * servers at the moment are not taken into account for the estimation
   * of the resources limits.
   */
  if (global.mode & MODE_STARTING)
    global.maxsock++;

  set_srv_agent_port(srv, atol(args[*cur_arg + 1]));

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

int set_srv_agent_send(struct server *srv, const char *send)
{
  struct tcpcheck_rules *rules = srv->agent.tcpcheck_rules;
  struct tcpcheck_var *var = NULL;
  char *str;

  str = strdup(send);
  var = create_tcpcheck_var(ist("check.agent_string"));
  if (str == NULL || var == NULL)
    goto error;

  free_tcpcheck_vars(&rules->preset_vars);

  var->data.type = SMP_T_STR;
  var->data.u.str.area = str;
  var->data.u.str.data = strlen(str);
  LIST_INIT(&var->list);
  LIST_APPEND(&rules->preset_vars, &var->list);

  return 1;

  error:
  free(str);
  free(var);
  return 0;
}

/* Parse the "agent-send" server keyword */
static int srv_parse_agent_send(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
        char **errmsg)
{
  struct tcpcheck_rules *rules = srv->agent.tcpcheck_rules;
  int err_code = 0;

  if (!*(args[*cur_arg+1])) {
    memprintf(errmsg, "'%s' expects a string as argument.", args[*cur_arg]);
    goto error;
  }

  if (!rules) {
    rules = calloc(1, sizeof(*rules));
    if (!rules) {
      memprintf(errmsg, "out of memory.");
      goto error;
    }
    LIST_INIT(&rules->preset_vars);
    srv->agent.tcpcheck_rules = rules;
  }

  if (!set_srv_agent_send(srv, args[*cur_arg+1])) {
    memprintf(errmsg, "out of memory.");
    goto error;
  }

  out:
  return err_code;

  error:
  deinit_srv_agent_check(srv);
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "no-agent-send" server keyword */
static int srv_parse_no_agent_check(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
            char **errmsg)
{
  deinit_srv_agent_check(srv);
  return 0;
}

/* Parse the "check" server keyword */
static int srv_parse_check(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
         char **errmsg)
{
  if (!(curpx->cap & PR_CAP_BE)) {
    memprintf(errmsg, "'%s' ignored because %s '%s' has no backend capability",
        args[*cur_arg], proxy_type_str(curpx), curpx->id);
    return ERR_WARN;
  }

  srv->do_check = 1;
  return 0;
}

/* Parse the "check-send-proxy" server keyword */
static int srv_parse_check_send_proxy(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
              char **errmsg)
{
  srv->check.send_proxy = 1;
  return 0;
}

/* Parse the "check-via-socks4" server keyword */
static int srv_parse_check_via_socks4(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
              char **errmsg)
{
  srv->check.via_socks4 = 1;
  return 0;
}

/* Parse the "no-check" server keyword */
static int srv_parse_no_check(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
            char **errmsg)
{
  deinit_srv_check(srv);
  return 0;
}

/* Parse the "no-check-reuse-pool" server keyword */
static int srv_parse_no_check_reuse_pool(char **args, int *cur_arg,
                                         struct proxy *curpx, struct server *srv,
                                         char **errmsg)
{
  srv->check.reuse_pool = 0;
  return 0;
}

/* Parse the "no-check-send-proxy" server keyword */
static int srv_parse_no_check_send_proxy(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
           char **errmsg)
{
  srv->check.send_proxy = 0;
  return 0;
}

/* parse the "check-pool-conn-name" server keyword */
static int srv_parse_check_pool_conn_name(char **args, int *cur_arg,
                                          struct proxy *px,
                                          struct server *newsrv, char **err)
{
  int err_code = 0;

  if (!*args[*cur_arg + 1]) {
    memprintf(err, "'%s' : missing value", args[*cur_arg]);
    goto error;
  }

  ha_free(&newsrv->check.pool_conn_name);
  newsrv->check.pool_conn_name = strdup(args[*cur_arg + 1]);
  if (!newsrv->check.pool_conn_name) {
    memprintf(err, "'%s' : out of memory", args[*cur_arg]);
    return ERR_ALERT | ERR_FATAL;
  }

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}


/* parse the "check-proto" server keyword */
static int srv_parse_check_proto(char **args, int *cur_arg,
         struct proxy *px, struct server *newsrv, char **err)
{
  int err_code = 0;

  if (!*args[*cur_arg + 1]) {
    memprintf(err, "'%s' : missing value", args[*cur_arg]);
    goto error;
  }
  newsrv->check.mux_proto = get_mux_proto(ist(args[*cur_arg + 1]));
  if (!newsrv->check.mux_proto) {
    memprintf(err, "'%s' :  unknown MUX protocol '%s'", args[*cur_arg], args[*cur_arg+1]);
    goto error;
  }

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "check-reuse-pool" server keyword */
static int srv_parse_check_reuse_pool(char **args, int *cur_arg,
                                      struct proxy *curpx, struct server *srv,
                                      char **errmsg)
{
  srv->check.reuse_pool = 1;
  return 0;
}


/* Parse the "rise" server keyword */
static int srv_parse_check_rise(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
        char **errmsg)
{
  int err_code = 0;

  if (!*args[*cur_arg + 1]) {
    memprintf(errmsg, "'%s' expects an integer argument.", args[*cur_arg]);
    goto error;
  }

  srv->check.rise = atol(args[*cur_arg+1]);
  if (srv->check.rise <= 0) {
    memprintf(errmsg, "'%s' has to be > 0.", args[*cur_arg]);
    goto error;
  }

  if (srv->check.health)
    srv->check.health = srv->check.rise;

  out:
  return err_code;

  error:
  deinit_srv_agent_check(srv);
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "fall" server keyword */
static int srv_parse_check_fall(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
        char **errmsg)
{
  int err_code = 0;

  if (!*args[*cur_arg + 1]) {
    memprintf(errmsg, "'%s' expects an integer argument.", args[*cur_arg]);
    goto error;
  }

  srv->check.fall = atol(args[*cur_arg+1]);
  if (srv->check.fall <= 0) {
    memprintf(errmsg, "'%s' has to be > 0.", args[*cur_arg]);
    goto error;
  }

  out:
  return err_code;

  error:
  deinit_srv_agent_check(srv);
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "inter" server keyword */
static int srv_parse_check_inter(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
         char **errmsg)
{
  const char *err = NULL;
  unsigned int delay;
  int err_code = 0;

  if (!*(args[*cur_arg+1])) {
    memprintf(errmsg, "'%s' expects a delay as argument.", args[*cur_arg]);
    goto error;
  }

  err = parse_time_err(args[*cur_arg+1], &delay, TIME_UNIT_MS);
  if (err == PARSE_TIME_OVER) {
    memprintf(errmsg, "timer overflow in argument <%s> to <%s> of server %s, maximum value is 2147483647 ms (~24.8 days).",
        args[*cur_arg+1], args[*cur_arg], srv->id);
    goto error;
  }
  else if (err == PARSE_TIME_UNDER) {
    memprintf(errmsg, "timer underflow in argument <%s> to <%s> of server %s, minimum non-null value is 1 ms.",
        args[*cur_arg+1], args[*cur_arg], srv->id);
    goto error;
  }
  else if (err) {
    memprintf(errmsg, "unexpected character '%c' in 'agent-inter' argument of server %s.",
        *err, srv->id);
    goto error;
  }
  if (delay <= 0) {
    memprintf(errmsg, "invalid value %d for argument '%s' of server %s.",
        delay, args[*cur_arg], srv->id);
    goto error;
  }
  srv->check.inter = delay;

  if (warn_if_lower(args[*cur_arg+1], 100)) {
    memprintf(errmsg, "'%s %u' in server '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent",
              args[*cur_arg], delay, srv->id, delay);
    err_code |= ERR_WARN;
  }

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}


/* Parse the "fastinter" server keyword */
static int srv_parse_check_fastinter(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
             char **errmsg)
{
  const char *err = NULL;
  unsigned int delay;
  int err_code = 0;

  if (!*(args[*cur_arg+1])) {
    memprintf(errmsg, "'%s' expects a delay as argument.", args[*cur_arg]);
    goto error;
  }

  err = parse_time_err(args[*cur_arg+1], &delay, TIME_UNIT_MS);
  if (err == PARSE_TIME_OVER) {
    memprintf(errmsg, "timer overflow in argument <%s> to <%s> of server %s, maximum value is 2147483647 ms (~24.8 days).",
        args[*cur_arg+1], args[*cur_arg], srv->id);
    goto error;
  }
  else if (err == PARSE_TIME_UNDER) {
    memprintf(errmsg, "timer underflow in argument <%s> to <%s> of server %s, minimum non-null value is 1 ms.",
        args[*cur_arg+1], args[*cur_arg], srv->id);
    goto error;
  }
  else if (err) {
    memprintf(errmsg, "unexpected character '%c' in 'agent-inter' argument of server %s.",
        *err, srv->id);
    goto error;
  }
  if (delay <= 0) {
    memprintf(errmsg, "invalid value %d for argument '%s' of server %s.",
        delay, args[*cur_arg], srv->id);
    goto error;
  }
  srv->check.fastinter = delay;

  if (warn_if_lower(args[*cur_arg+1], 100)) {
    memprintf(errmsg, "'%s %u' in server '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent",
              args[*cur_arg], delay, srv->id, delay);
    err_code |= ERR_WARN;
  }

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}


/* Parse the "downinter" server keyword */
static int srv_parse_check_downinter(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
             char **errmsg)
{
  const char *err = NULL;
  unsigned int delay;
  int err_code = 0;

  if (!*(args[*cur_arg+1])) {
    memprintf(errmsg, "'%s' expects a delay as argument.", args[*cur_arg]);
    goto error;
  }

  err = parse_time_err(args[*cur_arg+1], &delay, TIME_UNIT_MS);
  if (err == PARSE_TIME_OVER) {
    memprintf(errmsg, "timer overflow in argument <%s> to <%s> of server %s, maximum value is 2147483647 ms (~24.8 days).",
        args[*cur_arg+1], args[*cur_arg], srv->id);
    goto error;
  }
  else if (err == PARSE_TIME_UNDER) {
    memprintf(errmsg, "timer underflow in argument <%s> to <%s> of server %s, minimum non-null value is 1 ms.",
        args[*cur_arg+1], args[*cur_arg], srv->id);
    goto error;
  }
  else if (err) {
    memprintf(errmsg, "unexpected character '%c' in 'agent-inter' argument of server %s.",
        *err, srv->id);
    goto error;
  }
  if (delay <= 0) {
    memprintf(errmsg, "invalid value %d for argument '%s' of server %s.",
        delay, args[*cur_arg], srv->id);
    goto error;
  }
  srv->check.downinter = delay;

  if (warn_if_lower(args[*cur_arg+1], 100)) {
    memprintf(errmsg, "'%s %u' in server '%s' is suspiciously small for a value in milliseconds. Please use an explicit unit ('%ums') if that was the intent",
              args[*cur_arg], delay, srv->id, delay);
    err_code |= ERR_WARN;
  }

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* Parse the "port" server keyword */
static int srv_parse_check_port(char **args, int *cur_arg, struct proxy *curpx, struct server *srv,
        char **errmsg)
{
  int err_code = 0;

  if (!*(args[*cur_arg+1])) {
    memprintf(errmsg, "'%s' expects a port number as argument.", args[*cur_arg]);
    goto error;
  }

  /* Only increment maxsock for servers from the configuration. Dynamic
   * servers at the moment are not taken into account for the estimation
   * of the resources limits.
   */
  if (global.mode & MODE_STARTING)
    global.maxsock++;

  srv->check.port = atol(args[*cur_arg+1]);
  /* if agentport was never set, we can use port */
  if (!(srv->flags & SRV_F_AGENTPORT))
    srv->agent.port = srv->check.port;

  out:
  return err_code;

  error:
  err_code |= ERR_ALERT | ERR_FATAL;
  goto out;
}

/* config parser for global "tune.max-checks-per-thread" */
static int check_parse_global_max_checks(char **args, int section_type, struct proxy *curpx,
                                       const struct proxy *defpx, const char *file, int line,
                                       char **err)
{
  if (too_many_args(1, args, err, NULL))
    return -1;
  global.tune.max_checks_per_thread = atoi(args[1]);
  return 0;
}

/* register "global" section keywords */
static struct cfg_kw_list chk_cfg_kws = {ILH, {
  { CFG_GLOBAL, "tune.max-checks-per-thread", check_parse_global_max_checks },
  { 0, NULL, NULL }
}};

INITCALL1(STG_REGISTER, cfg_register_keywords, &chk_cfg_kws);

/* register "server" line keywords */
static struct srv_kw_list srv_kws = { "CHK", { }, {
  { "addr",                srv_parse_addr,                1,  1,  1 }, /* IP address to send health to or to probe from agent-check */
  { "agent-addr",          srv_parse_agent_addr,          1,  1,  1 }, /* Enable an auxiliary agent check */
  { "agent-check",         srv_parse_agent_check,         0,  1,  1 }, /* Enable agent checks */
  { "agent-inter",         srv_parse_agent_inter,         1,  1,  1 }, /* Set the interval between two agent checks */
  { "agent-port",          srv_parse_agent_port,          1,  1,  1 }, /* Set the TCP port used for agent checks. */
  { "agent-send",          srv_parse_agent_send,          1,  1,  1 }, /* Set string to send to agent. */
  { "check",               srv_parse_check,               0,  1,  1 }, /* Enable health checks */
  { "check-pool-conn-name", srv_parse_check_pool_conn_name, 1, 1, 1 }, /* */
  { "check-proto",         srv_parse_check_proto,         1,  1,  1 }, /* Set the mux protocol for health checks  */
  { "check-reuse-pool",    srv_parse_check_reuse_pool,    0,  1,  1 }, /* Allows to reuse idle connections for checks */
  { "check-send-proxy",    srv_parse_check_send_proxy,    0,  1,  1 }, /* Enable PROXY protocol for health checks */
  { "check-via-socks4",    srv_parse_check_via_socks4,    0,  1,  1 }, /* Enable socks4 proxy for health checks */
  { "no-agent-check",      srv_parse_no_agent_check,      0,  1,  0 }, /* Do not enable any auxiliary agent check */
  { "no-check",            srv_parse_no_check,            0,  1,  0 }, /* Disable health checks */
  { "no-check-reuse-pool", srv_parse_no_check_reuse_pool, 0,  1,  0 }, /* Disable PROXY protocol for health checks */
  { "no-check-send-proxy", srv_parse_no_check_send_proxy, 0,  1,  0 }, /* Disable PROXY protocol for health checks */
  { "rise",                srv_parse_check_rise,          1,  1,  1 }, /* Set rise value for health checks */
  { "fall",                srv_parse_check_fall,          1,  1,  1 }, /* Set fall value for health checks */
  { "inter",               srv_parse_check_inter,         1,  1,  1 }, /* Set inter value for health checks */
  { "fastinter",           srv_parse_check_fastinter,     1,  1,  1 }, /* Set fastinter value for health checks */
  { "downinter",           srv_parse_check_downinter,     1,  1,  1 }, /* Set downinter value for health checks */
  { "port",                srv_parse_check_port,          1,  1,  1 }, /* Set the TCP port used for health checks. */
  { NULL, NULL, 0 },
}};

INITCALL1(STG_REGISTER, srv_register_keywords, &srv_kws);

/*
 * Local variables:
 *  c-indent-level: 8
 *  c-basic-offset: 8
 * End:
 */

Coverage Report

Created: 2026-01-10 06:07