mod_proxy_balancer.c

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* Load balancer module for Apache proxy */

#include "mod_proxy.h"
#include "scoreboard.h"
#include "ap_mpm.h"
#include "apr_version.h"
#include "ap_hooks.h"
#include "apr_date.h"
#include "mod_watchdog.h"

static const char *balancer_mutex_type = "proxy-balancer-shm";
ap_slotmem_provider_t *storage = NULL;

module AP_MODULE_DECLARE_DATA proxy_balancer_module;

static APR_OPTIONAL_FN_TYPE(set_worker_hc_param) *set_worker_hc_param_f = NULL;

static int (*ap_proxy_retry_worker_fn)(const char *proxy_function,
        proxy_worker *worker, server_rec *s) = NULL;

static APR_OPTIONAL_FN_TYPE(hc_show_exprs) *hc_show_exprs_f = NULL;
static APR_OPTIONAL_FN_TYPE(hc_select_exprs) *hc_select_exprs_f = NULL;
static APR_OPTIONAL_FN_TYPE(hc_valid_expr) *hc_valid_expr_f = NULL;


/*
 * Register our mutex type before the config is read so we
 * can adjust the mutex settings using the Mutex directive.
 */
static int balancer_pre_config(apr_pool_t *pconf, apr_pool_t *plog,
                               apr_pool_t *ptemp)
{

    apr_status_t rv;

    rv = ap_mutex_register(pconf, balancer_mutex_type, NULL,
                               APR_LOCK_DEFAULT, 0);
    if (rv != APR_SUCCESS) {
        return rv;
    }
    set_worker_hc_param_f = APR_RETRIEVE_OPTIONAL_FN(set_worker_hc_param);
    hc_show_exprs_f = APR_RETRIEVE_OPTIONAL_FN(hc_show_exprs);
    hc_select_exprs_f = APR_RETRIEVE_OPTIONAL_FN(hc_select_exprs);
    hc_valid_expr_f = APR_RETRIEVE_OPTIONAL_FN(hc_valid_expr);
    return OK;
}

#if 0
extern void proxy_update_members(proxy_balancer **balancer, request_rec *r,
                                 proxy_server_conf *conf);
#endif

static int proxy_balancer_canon(request_rec *r, char *url)
{
    char *host, *path;
    char *search = NULL;
    const char *err;
    apr_port_t port = 0;

    /* TODO: offset of BALANCER_PREFIX ?? */
    if (strncasecmp(url, "balancer:", 9) == 0) {
        url += 9;
    }
    else {
        return DECLINED;
    }

    ap_log_rerror(APLOG_MARK, APLOG_TRACE1, 0, r, "canonicalising URL %s", url);

    /* do syntatic check.
     * We break the URL into host, port, path, search
     */
    err = ap_proxy_canon_netloc(r->pool, &url, NULL, NULL, &host, &port);
    if (err) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01157)
                      "error parsing URL %s: %s",
                      url, err);
        return HTTP_BAD_REQUEST;
    }
    /*
     * now parse path/search args, according to rfc1738:
     * process the path. With proxy-noncanon set (by
     * mod_proxy) we use the raw, unparsed uri
     */
    if (apr_table_get(r->notes, "proxy-nocanon")) {
        path = url;   /* this is the raw path */
    }
    else {
        path = ap_proxy_canonenc(r->pool, url, strlen(url), enc_path, 0,
                                 r->proxyreq);
        search = r->args;
    }
    if (path == NULL)
        return HTTP_BAD_REQUEST;

    r->filename = apr_pstrcat(r->pool, "proxy:" BALANCER_PREFIX, host,
            "/", path, (search) ? "?" : "", (search) ? search : "", NULL);

    r->path_info = apr_pstrcat(r->pool, "/", path, NULL);

    return OK;
}

static void init_balancer_members(apr_pool_t *p, server_rec *s,
                                 proxy_balancer *balancer)
{
    int i;
    proxy_worker **workers;

    workers = (proxy_worker **)balancer->workers->elts;

    for (i = 0; i < balancer->workers->nelts; i++) {
        int worker_is_initialized;
        proxy_worker *worker = *workers;
        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01158)
                     "Looking at %s -> %s initialized?", balancer->s->name,
                     ap_proxy_worker_name(p, worker));
        worker_is_initialized = PROXY_WORKER_IS_INITIALIZED(worker);
        if (!worker_is_initialized) {
            ap_proxy_initialize_worker(worker, s, p);
        }
        ++workers;
    }

    /* Set default number of attempts to the number of
     * workers.
     */
    if (!balancer->s->max_attempts_set && balancer->workers->nelts > 1) {
        balancer->s->max_attempts = balancer->workers->nelts - 1;
        balancer->s->max_attempts_set = 1;
    }
}

/* Retrieve the parameter with the given name
 * Something like 'JSESSIONID=12345...N'
 */
static char *get_path_param(apr_pool_t *pool, char *url,
                            const char *name, int scolon_sep)
{
    char *path = NULL;
    char *pathdelims = "?&";

    if (scolon_sep) {
        pathdelims = ";?&";
    }
    for (path = strstr(url, name); path; path = strstr(path + 1, name)) {
        path += strlen(name);
        if (*path == '=') {
            /*
             * Session path was found, get its value
             */
            ++path;
            if (*path) {
                char *q;
                path = apr_strtok(apr_pstrdup(pool, path), pathdelims, &q);
                return path;
            }
        }
    }
    return NULL;
}

static char *get_cookie_param(request_rec *r, const char *name)
{
    const char *cookies;
    const char *start_cookie;

    if ((cookies = apr_table_get(r->headers_in, "Cookie"))) {
        for (start_cookie = ap_strstr_c(cookies, name); start_cookie;
             start_cookie = ap_strstr_c(start_cookie + 1, name)) {
            if (start_cookie == cookies ||
                start_cookie[-1] == ';' ||
                start_cookie[-1] == ',' ||
                isspace(start_cookie[-1])) {

                start_cookie += strlen(name);
                while(*start_cookie && isspace(*start_cookie))
                    ++start_cookie;
                if (*start_cookie++ == '=' && *start_cookie) {
                    /*
                     * Session cookie was found, get its value
                     */
                    char *end_cookie, *cookie;
                    cookie = apr_pstrdup(r->pool, start_cookie);
                    if ((end_cookie = strchr(cookie, ';')) != NULL)
                        *end_cookie = '\0';
                    if((end_cookie = strchr(cookie, ',')) != NULL)
                        *end_cookie = '\0';
                    return cookie;
                }
            }
        }
    }
    return NULL;
}

/* Find the worker that has the 'route' defined
 */
static proxy_worker *find_route_worker(proxy_balancer *balancer,
                                       const char *route, request_rec *r,
                                       int recursion)
{
    int i;
    int checking_standby;
    int checked_standby;

    proxy_worker **workers;

    checking_standby = checked_standby = 0;
    while (!checked_standby) {
        workers = (proxy_worker **)balancer->workers->elts;
        for (i = 0; i < balancer->workers->nelts; i++, workers++) {
            proxy_worker *worker = *workers;
            if ( (checking_standby ? !PROXY_WORKER_IS_STANDBY(worker) : PROXY_WORKER_IS_STANDBY(worker)) )
                continue;
            if (*(worker->s->route) && strcmp(worker->s->route, route) == 0) {
                if (PROXY_WORKER_IS_USABLE(worker)) {
                    return worker;
                } else {
                    /*
                     * If the worker is in error state run
                     * retry on that worker. It will be marked as
                     * operational if the retry timeout is elapsed.
                     * The worker might still be unusable, but we try
                     * anyway.
                     */
                    ap_proxy_retry_worker_fn("BALANCER", worker, r->server);
                    if (PROXY_WORKER_IS_USABLE(worker)) {
                            return worker;
                    } else {
                        /*
                         * We have a worker that is unusable.
                         * It can be in error or disabled, but in case
                         * it has a redirection set use that redirection worker.
                         * This enables to safely remove the member from the
                         * balancer. Of course you will need some kind of
                         * session replication between those two remote.
                         * Also check that we haven't gone thru all the
                         * balancer members by means of redirects.
                         * This should avoid redirect cycles.
                         */
                        if ((*worker->s->redirect)
                            && (recursion < balancer->workers->nelts)) {
                            proxy_worker *rworker = NULL;
                            rworker = find_route_worker(balancer, worker->s->redirect,
                                                        r, recursion + 1);
                            /* Check if the redirect worker is usable */
                            if (rworker && !PROXY_WORKER_IS_USABLE(rworker)) {
                                /*
                                 * If the worker is in error state run
                                 * retry on that worker. It will be marked as
                                 * operational if the retry timeout is elapsed.
                                 * The worker might still be unusable, but we try
                                 * anyway.
                                 */
                                ap_proxy_retry_worker_fn("BALANCER", rworker, r->server);
                            }
                            if (rworker && PROXY_WORKER_IS_USABLE(rworker))
                                return rworker;
                        }
                    }
                }
            }
        }
        checked_standby = checking_standby++;
    }
    return NULL;
}

static proxy_worker *find_session_route(proxy_balancer *balancer,
                                        request_rec *r,
                                        char **route,
                                        const char **sticky_used,
                                        char **url)
{
    proxy_worker *worker = NULL;

    if (!*balancer->s->sticky)
        return NULL;
    /* Try to find the sticky route inside url */
    *route = get_path_param(r->pool, *url, balancer->s->sticky_path, balancer->s->scolonsep);
    if (*route) {
        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01159)
                     "Found value %s for stickysession %s",
                     *route, balancer->s->sticky_path);
        *sticky_used =  balancer->s->sticky_path;
    }
    else {
        *route = get_cookie_param(r, balancer->s->sticky);
        if (*route) {
            *sticky_used =  balancer->s->sticky;
            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01160)
                         "Found value %s for stickysession %s",
                         *route, balancer->s->sticky);
        }
    }
    /*
     * If we found a value for stickysession, find the first '.' (or whatever
     * sticky_separator is set to) within. Everything after '.' (if present)
     * is our route. 
     */
    if ((*route) && (balancer->s->sticky_separator != 0) && ((*route = strchr(*route, balancer->s->sticky_separator)) != NULL ))
        (*route)++;
    if ((*route) && (**route)) {
        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01161) "Found route %s", *route);
        /* We have a route in path or in cookie
         * Find the worker that has this route defined.
         */
        worker = find_route_worker(balancer, *route, r, 1);
        if (worker && strcmp(*route, worker->s->route)) {
            /*
             * Notice that the route of the worker chosen is different from
             * the route supplied by the client.
             */
            apr_table_setn(r->subprocess_env, "BALANCER_ROUTE_CHANGED", "1");
            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01162)
                          "Route changed from %s to %s",
                          *route, worker->s->route);
        }
        return worker;
    }
    else
        return NULL;
}

static proxy_worker *find_best_worker(proxy_balancer *balancer,
                                      request_rec *r)
{
    proxy_worker *candidate = NULL;
    apr_status_t rv;

    if ((rv = PROXY_THREAD_LOCK(balancer)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(01163)
                      "%s: Lock failed for find_best_worker()",
                      balancer->s->name);
        return NULL;
    }

    candidate = (*balancer->lbmethod->finder)(balancer, r);

    if (candidate)
        candidate->s->elected++;

    if ((rv = PROXY_THREAD_UNLOCK(balancer)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(01164)
                      "%s: Unlock failed for find_best_worker()",
                      balancer->s->name);
    }

    if (candidate == NULL) {
        /* All the workers are in error state or disabled.
         * If the balancer has a timeout sleep for a while
         * and try again to find the worker. The chances are
         * that some other thread will release a connection.
         * By default the timeout is not set, and the server
         * returns SERVER_BUSY.
         */
        if (balancer->s->timeout) {
            /* XXX: This can perhaps be build using some
             * smarter mechanism, like tread_cond.
             * But since the statuses can came from
             * different childs, use the provided algo.
             */
            apr_interval_time_t timeout = balancer->s->timeout;
            apr_interval_time_t step, tval = 0;
            /* Set the timeout to 0 so that we don't
             * end in infinite loop
             */
            balancer->s->timeout = 0;
            step = timeout / 100;
            while (tval < timeout) {
                apr_sleep(step);
                /* Try again */
                if ((candidate = find_best_worker(balancer, r)))
                    break;
                tval += step;
            }
            /* restore the timeout */
            balancer->s->timeout = timeout;
        }
    }

    return candidate;

}

static int rewrite_url(request_rec *r, proxy_worker *worker,
                        char **url)
{
    const char *scheme = strstr(*url, "://");
    const char *path = NULL;

    if (scheme)
        path = ap_strchr_c(scheme + 3, '/');

    /* we break the URL into host, port, uri */
    if (!worker) {
        return ap_proxyerror(r, HTTP_BAD_REQUEST, apr_pstrcat(r->pool,
                             "missing worker. URI cannot be parsed: ", *url,
                             NULL));
    }

    *url = apr_pstrcat(r->pool, worker->s->name, path, NULL);

    return OK;
}

static void force_recovery(proxy_balancer *balancer, server_rec *s)
{
    int i;
    int ok = 0;
    proxy_worker **worker;

    worker = (proxy_worker **)balancer->workers->elts;
    for (i = 0; i < balancer->workers->nelts; i++, worker++) {
        if (!((*worker)->s->status & PROXY_WORKER_IN_ERROR)) {
            ok = 1;
            break;
        }
        else {
            /* Try if we can recover */
            ap_proxy_retry_worker_fn("BALANCER", *worker, s);
            if (!((*worker)->s->status & PROXY_WORKER_IN_ERROR)) {
                ok = 1;
                break;
            }
        }
    }
    if (!ok && balancer->s->forcerecovery) {
        /* If all workers are in error state force the recovery.
         */
        worker = (proxy_worker **)balancer->workers->elts;
        for (i = 0; i < balancer->workers->nelts; i++, worker++) {
            ++(*worker)->s->retries;
            (*worker)->s->status &= ~PROXY_WORKER_IN_ERROR;
            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01165)
                         "%s: Forcing recovery for worker (%s)",
                         balancer->s->name, (*worker)->s->hostname);
        }
    }
}

static apr_status_t decrement_busy_count(void *worker_)
{
    proxy_worker *worker = worker_;
    
    if (worker->s->busy) {
        worker->s->busy--;
    }

    return APR_SUCCESS;
}

static int proxy_balancer_pre_request(proxy_worker **worker,
                                      proxy_balancer **balancer,
                                      request_rec *r,
                                      proxy_server_conf *conf, char **url)
{
    int access_status;
    proxy_worker *runtime;
    char *route = NULL;
    const char *sticky = NULL;
    apr_status_t rv;

    *worker = NULL;
    /* Step 1: check if the url is for us
     * The url we can handle starts with 'balancer://'
     * If balancer is already provided skip the search
     * for balancer, because this is failover attempt.
     */
    if (!*balancer &&
        !(*balancer = ap_proxy_get_balancer(r->pool, conf, *url, 1)))
        return DECLINED;

    /* Step 2: Lock the LoadBalancer
     * XXX: perhaps we need the process lock here
     */
    if ((rv = PROXY_THREAD_LOCK(*balancer)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(01166)
                      "%s: Lock failed for pre_request", (*balancer)->s->name);
        return DECLINED;
    }

    /* Step 3: force recovery */
    force_recovery(*balancer, r->server);

    /* Step 3.5: Update member list for the balancer */
    /* TODO: Implement as provider! */
    ap_proxy_sync_balancer(*balancer, r->server, conf);

    /* Step 4: find the session route */
    runtime = find_session_route(*balancer, r, &route, &sticky, url);
    if (runtime) {
        if ((*balancer)->lbmethod && (*balancer)->lbmethod->updatelbstatus) {
            /* Call the LB implementation */
            (*balancer)->lbmethod->updatelbstatus(*balancer, runtime, r->server);
        }
        else { /* Use the default one */
            int i, total_factor = 0;
            proxy_worker **workers;
            /* We have a sticky load balancer
             * Update the workers status
             * so that even session routes get
             * into account.
             */
            workers = (proxy_worker **)(*balancer)->workers->elts;
            for (i = 0; i < (*balancer)->workers->nelts; i++) {
                /* Take into calculation only the workers that are
                 * not in error state or not disabled.
                 */
                if (PROXY_WORKER_IS_USABLE(*workers)) {
                    (*workers)->s->lbstatus += (*workers)->s->lbfactor;
                    total_factor += (*workers)->s->lbfactor;
                }
                workers++;
            }
            runtime->s->lbstatus -= total_factor;
        }
        runtime->s->elected++;

        *worker = runtime;
    }
    else if (route && (*balancer)->s->sticky_force) {
        int i, member_of = 0;
        proxy_worker **workers;
        /*
         * We have a route provided that doesn't match the
         * balancer name. See if the provider route is the
         * member of the same balancer in which case return 503
         */
        workers = (proxy_worker **)(*balancer)->workers->elts;
        for (i = 0; i < (*balancer)->workers->nelts; i++) {
            if (*((*workers)->s->route) && strcmp((*workers)->s->route, route) == 0) {
                member_of = 1;
                break;
            }
            workers++;
        }
        if (member_of) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01167)
                          "%s: All workers are in error state for route (%s)",
                          (*balancer)->s->name, route);
            if ((rv = PROXY_THREAD_UNLOCK(*balancer)) != APR_SUCCESS) {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(01168)
                              "%s: Unlock failed for pre_request",
                              (*balancer)->s->name);
            }
            return HTTP_SERVICE_UNAVAILABLE;
        }
    }

    if ((rv = PROXY_THREAD_UNLOCK(*balancer)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(01169)
                      "%s: Unlock failed for pre_request",
                      (*balancer)->s->name);
    }
    if (!*worker) {
        runtime = find_best_worker(*balancer, r);
        if (!runtime) {
            if ((*balancer)->workers->nelts) {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01170)
                              "%s: All workers are in error state",
                              (*balancer)->s->name);
            } else {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01171)
                              "%s: No workers in balancer",
                              (*balancer)->s->name);
            }

            return HTTP_SERVICE_UNAVAILABLE;
        }
        if (*(*balancer)->s->sticky && runtime) {
            /*
             * This balancer has sticky sessions and the client either has not
             * supplied any routing information or all workers for this route
             * including possible redirect and hotstandby workers are in error
             * state, but we have found another working worker for this
             * balancer where we can send the request. Thus notice that we have
             * changed the route to the backend.
             */
            apr_table_setn(r->subprocess_env, "BALANCER_ROUTE_CHANGED", "1");
        }
        *worker = runtime;
    }

    (*worker)->s->busy++;
    apr_pool_cleanup_register(r->pool, *worker, decrement_busy_count,
                              apr_pool_cleanup_null);

    /* Add balancer/worker info to env. */
    apr_table_setn(r->subprocess_env,
                   "BALANCER_NAME", (*balancer)->s->name);
    apr_table_setn(r->subprocess_env,
                   "BALANCER_WORKER_NAME", (*worker)->s->name);
    apr_table_setn(r->subprocess_env,
                   "BALANCER_WORKER_ROUTE", (*worker)->s->route);

    /* Rewrite the url from 'balancer://url'
     * to the 'worker_scheme://worker_hostname[:worker_port]/url'
     * This replaces the balancers fictional name with the
     * real hostname of the elected worker.
     */
    access_status = rewrite_url(r, *worker, url);
    /* Add the session route to request notes if present */
    if (route) {
        apr_table_setn(r->notes, "session-sticky", sticky);
        apr_table_setn(r->notes, "session-route", route);

        /* Add session info to env. */
        apr_table_setn(r->subprocess_env,
                       "BALANCER_SESSION_STICKY", sticky);
        apr_table_setn(r->subprocess_env,
                       "BALANCER_SESSION_ROUTE", route);
    }
    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01172)
                  "%s: worker (%s) rewritten to %s",
                  (*balancer)->s->name, (*worker)->s->name, *url);

    return access_status;
}

static int proxy_balancer_post_request(proxy_worker *worker,
                                       proxy_balancer *balancer,
                                       request_rec *r,
                                       proxy_server_conf *conf)
{

    apr_status_t rv;

    if ((rv = PROXY_THREAD_LOCK(balancer)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(01173)
                      "%s: Lock failed for post_request",
                      balancer->s->name);
        return HTTP_INTERNAL_SERVER_ERROR;
    }

    if (!apr_is_empty_array(balancer->errstatuses)
        && !(worker->s->status & PROXY_WORKER_IGNORE_ERRORS)) {
        int i;
        for (i = 0; i < balancer->errstatuses->nelts; i++) {
            int val = ((int *)balancer->errstatuses->elts)[i];
            if (r->status == val) {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01174)
                              "%s: Forcing worker (%s) into error state "
                              "due to status code %d matching 'failonstatus' "
                              "balancer parameter",
                              balancer->s->name, ap_proxy_worker_name(r->pool, worker),
                              val);
                worker->s->status |= PROXY_WORKER_IN_ERROR;
                worker->s->error_time = apr_time_now();
                break;
            }
        }
    }

    if (balancer->failontimeout
        && !(worker->s->status & PROXY_WORKER_IGNORE_ERRORS)
        && (apr_table_get(r->notes, "proxy_timedout")) != NULL) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02460)
                      "%s: Forcing worker (%s) into error state "
                      "due to timeout and 'failontimeout' parameter being set",
                       balancer->s->name, ap_proxy_worker_name(r->pool, worker));
        worker->s->status |= PROXY_WORKER_IN_ERROR;
        worker->s->error_time = apr_time_now();

    }

    if ((rv = PROXY_THREAD_UNLOCK(balancer)) != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(01175)
                      "%s: Unlock failed for post_request", balancer->s->name);
    }
    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01176)
                  "proxy_balancer_post_request for (%s)", balancer->s->name);

    return OK;
}

static void recalc_factors(proxy_balancer *balancer)
{
    int i;
    proxy_worker **workers;


    /* Recalculate lbfactors */
    workers = (proxy_worker **)balancer->workers->elts;
    /* Special case if there is only one worker its
     * load factor will always be 100
     */
    if (balancer->workers->nelts == 1) {
        (*workers)->s->lbstatus = (*workers)->s->lbfactor = 100;
        return;
    }
    for (i = 0; i < balancer->workers->nelts; i++) {
        /* Update the status entries */
        workers[i]->s->lbstatus = workers[i]->s->lbfactor;
    }
}

static apr_status_t lock_remove(void *data)
{
    int i;
    proxy_balancer *balancer;
    server_rec *s = data;
    void *sconf = s->module_config;
    proxy_server_conf *conf = (proxy_server_conf *) ap_get_module_config(sconf, &proxy_module);

    balancer = (proxy_balancer *)conf->balancers->elts;
    for (i = 0; i < conf->balancers->nelts; i++, balancer++) {
        if (balancer->gmutex) {
            apr_global_mutex_destroy(balancer->gmutex);
            balancer->gmutex = NULL;
        }
    }
    return(0);
}

/* post_config hook: */
static int balancer_post_config(apr_pool_t *pconf, apr_pool_t *plog,
                         apr_pool_t *ptemp, server_rec *s)
{
    apr_status_t rv;
    proxy_server_conf *conf;
    ap_slotmem_instance_t *new = NULL;
    apr_time_t tstamp;

    /* balancer_post_config() will be called twice during startup.  So, don't
     * set up the static data the 1st time through. */
    if (ap_state_query(AP_SQ_MAIN_STATE) == AP_SQ_MS_CREATE_PRE_CONFIG) {
        return OK;
    }

    if (!ap_proxy_retry_worker_fn) {
        ap_proxy_retry_worker_fn =
                APR_RETRIEVE_OPTIONAL_FN(ap_proxy_retry_worker);
        if (!ap_proxy_retry_worker_fn) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(02230)
                         "mod_proxy must be loaded for mod_proxy_balancer");
            return !OK;
        }
    }

    /*
     * Get slotmem setups
     */
    storage = ap_lookup_provider(AP_SLOTMEM_PROVIDER_GROUP, "shm",
                                 AP_SLOTMEM_PROVIDER_VERSION);
    if (!storage) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01177)
                     "Failed to lookup provider 'shm' for '%s': is "
                     "mod_slotmem_shm loaded??",
                     AP_SLOTMEM_PROVIDER_GROUP);
        return !OK;
    }

    tstamp = apr_time_now();
    /*
     * Go thru each Vhost and create the shared mem slotmem for
     * each balancer's workers
     */
    while (s) {
        int i,j;
        char *id;
        proxy_balancer *balancer;
        ap_slotmem_type_t type;
        void *sconf = s->module_config;
        conf = (proxy_server_conf *)ap_get_module_config(sconf, &proxy_module);
        /*
         * During create_proxy_config() we created a dummy id. Now that
         * we have identifying info, we can create the real id
         */
        id = apr_psprintf(pconf, "%s.%s.%d.%s.%s.%u.%s",
                          (s->server_scheme ? s->server_scheme : "????"),
                          (s->server_hostname ? s->server_hostname : "???"),
                          (int)s->port,
                          (s->server_admin ? s->server_admin : "??"),
                          (s->defn_name ? s->defn_name : "?"),
                          s->defn_line_number,
                          (s->error_fname ? s->error_fname : DEFAULT_ERRORLOG));
        conf->id = apr_psprintf(pconf, "p%x",
                                ap_proxy_hashfunc(id, PROXY_HASHFUNC_DEFAULT));
        if (conf->bslot) {
            /* Shared memory already created for this proxy_server_conf.
             */
            s = s->next;
            continue;
        }
        if (conf->bal_persist) {
            type = AP_SLOTMEM_TYPE_PERSIST;
        } else {
            type = 0;
        }
        if (conf->balancers->nelts) {
            conf->max_balancers = conf->balancers->nelts + conf->bgrowth;
            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01178) "Doing balancers create: %d, %d (%d)",
                         (int)ALIGNED_PROXY_BALANCER_SHARED_SIZE,
                         (int)conf->balancers->nelts, conf->max_balancers);

            rv = storage->create(&new, conf->id,
                                 ALIGNED_PROXY_BALANCER_SHARED_SIZE,
                                 conf->max_balancers, type, pconf);
            if (rv != APR_SUCCESS) {
                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01179) "balancer slotmem_create failed");
                return !OK;
            }
            conf->bslot = new;
        }
        conf->storage = storage;

        /* Initialize shared scoreboard data */
        balancer = (proxy_balancer *)conf->balancers->elts;
        for (i = 0; i < conf->balancers->nelts; i++, balancer++) {
            proxy_worker **workers;
            proxy_worker *worker;
            proxy_balancer_shared *bshm;
            const char *sname;
            unsigned int index;

            /* now that we have the right id, we need to redo the sname field */
            ap_pstr2_alnum(pconf, balancer->s->name + sizeof(BALANCER_PREFIX) - 1,
                           &sname);
            sname = apr_pstrcat(pconf, conf->id, "_", sname, NULL);
            PROXY_STRNCPY(balancer->s->sname, sname); /* We know this will succeed */

            balancer->max_workers = balancer->workers->nelts + balancer->growth;

            /* Create global mutex */
            rv = ap_global_mutex_create(&(balancer->gmutex), NULL, balancer_mutex_type,
                                        balancer->s->sname, s, pconf, 0);
            if (rv != APR_SUCCESS || !balancer->gmutex) {
                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01180)
                             "mutex creation of %s : %s failed", balancer_mutex_type,
                             balancer->s->sname);
                return HTTP_INTERNAL_SERVER_ERROR;
            }

            apr_pool_cleanup_register(pconf, (void *)s, lock_remove,
                                      apr_pool_cleanup_null);

            /* setup shm for balancers */
            bshm = ap_proxy_find_balancershm(storage, conf->bslot, balancer, &index);
            if (bshm) {
                if ((rv = storage->fgrab(conf->bslot, index)) != APR_SUCCESS) {
                    ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(02408) "balancer slotmem_fgrab failed");
                    return !OK;
                }
            }
            else {
                if ((rv = storage->grab(conf->bslot, &index)) != APR_SUCCESS) {
                    ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01181) "balancer slotmem_grab failed");
                    return !OK;
                }
                if ((rv = storage->dptr(conf->bslot, index, (void *)&bshm)) != APR_SUCCESS) {
                    ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01182) "balancer slotmem_dptr failed");
                    return !OK;
                }
            }
            if ((rv = ap_proxy_share_balancer(balancer, bshm, index)) != APR_SUCCESS) {
                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01183) "Cannot share balancer");
                return !OK;
            }

            /* create slotmem slots for workers */
            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01184) "Doing workers create: %s (%s), %d, %d [%u]",
                         balancer->s->name, balancer->s->sname,
                         (int)ALIGNED_PROXY_WORKER_SHARED_SIZE,
                         (int)balancer->max_workers, i);

            rv = storage->create(&new, balancer->s->sname,
                                 ALIGNED_PROXY_WORKER_SHARED_SIZE,
                                 balancer->max_workers, type, pconf);
            if (rv != APR_SUCCESS) {
                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01185) "worker slotmem_create failed");
                return !OK;
            }
            balancer->wslot = new;
            balancer->storage = storage;

            /* sync all timestamps */
            balancer->wupdated = balancer->s->wupdated = tstamp;

            /* now go thru each worker */
            workers = (proxy_worker **)balancer->workers->elts;
            for (j = 0; j < balancer->workers->nelts; j++, workers++) {
                proxy_worker_shared *shm;

                worker = *workers;

                shm = ap_proxy_find_workershm(storage, balancer->wslot, worker, &index);
                if (shm) {
                    if ((rv = storage->fgrab(balancer->wslot, index)) != APR_SUCCESS) {
                        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(02409) "worker slotmem_fgrab failed");
                        return !OK;
                    }
                }
                else {
                    if ((rv = storage->grab(balancer->wslot, &index)) != APR_SUCCESS) {
                        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01186) "worker slotmem_grab failed");
                        return !OK;

                    }
                    if ((rv = storage->dptr(balancer->wslot, index, (void *)&shm)) != APR_SUCCESS) {
                        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01187) "worker slotmem_dptr failed");
                        return !OK;
                    }
                }
                if ((rv = ap_proxy_share_worker(worker, shm, index)) != APR_SUCCESS) {
                    ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01188) "Cannot share worker");
                    return !OK;
                }
                worker->s->updated = tstamp;
            }
            if (conf->bal_persist) {
                /* We could have just read-in a persisted config. Force a sync. */
                balancer->wupdated--;
                ap_proxy_sync_balancer(balancer, s, conf);
            }
        }
        s = s->next;
    }

    return OK;
}

static void create_radio(const char *name, unsigned int flag, request_rec *r)
{
    ap_rvputs(r, "<td><label for='", name, "1'>On</label> <input name='", name, "' id='", name, "1' value='1' type=radio", NULL);
    if (flag)
        ap_rputs(" checked", r);
    ap_rvputs(r, "> <br/> <label for='", name, "0'>Off</label> <input name='", name, "' id='", name, "0' value='0' type=radio", NULL);
    if (!flag)
        ap_rputs(" checked", r);
    ap_rputs("></td>\n", r);
}

static void push2table(const char *input, apr_table_t *params,
                       const char *allowed[], apr_pool_t *p)
{
    char *args;
    char *tok, *val;
    char *key;

    if (input == NULL) {
        return;
    }
    args = apr_pstrdup(p, input);

    key = apr_strtok(args, "&", &tok);
    while (key) {
        val = strchr(key, '=');
        if (val) {
            *val++ = '\0';
        }
        else {
            val = "";
        }
        ap_unescape_url(key);
        ap_unescape_url(val);
        if (allowed == NULL) { /* allow all */
            apr_table_set(params, key, val);
        }
        else {
            const char **ok = allowed;
            while (*ok) {
                if (strcmp(*ok, key) == 0) {
                    apr_table_set(params, key, val);
                    break;
                }
                ok++;
            }
        }
        key = apr_strtok(NULL, "&", &tok);
    }
}

/* Manages the loadfactors and member status
 *   The balancer, worker and nonce are obtained from
 *   the request args (?b=...&w=...&nonce=....).
 *   All other params are pulled from any POST
 *   data that exists.
 * TODO:
 *   /.../<whatever>/balancer/worker/nonce
 */
static int balancer_handler(request_rec *r)
{