mod_proxy_balancer.c

来自「linux网络服务器工具」· C语言 代码 · 共 1,123 行 · 第 1/3 页

    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->name, path, NULL);

    return OK;
}

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;
    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)))
        return DECLINED;

    /* Step 2: find the session route */

    runtime = find_session_route(*balancer, r, &route, &sticky, url);
    /* Lock the LoadBalancer
     * XXX: perhaps we need the process lock here
     */
    if ((rv = PROXY_THREAD_LOCK(*balancer)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
                     "proxy: BALANCER: (%s). Lock failed for pre_request",
                     (*balancer)->name);
        return DECLINED;
    }
    if (runtime) {
        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.
             *
             * TODO: Abstract the below, since this is dependent
             *       on the LB implementation
             */
            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)->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_error(APLOG_MARK, APLOG_ERR, 0, r->server,
                         "proxy: BALANCER: (%s). All workers are in error state for route (%s)",
                         (*balancer)->name, route);
            if ((rv = PROXY_THREAD_UNLOCK(*balancer)) != APR_SUCCESS) {
                ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
                             "proxy: BALANCER: (%s). Unlock failed for pre_request",
                             (*balancer)->name);
            }
            return HTTP_SERVICE_UNAVAILABLE;
        }
    }

    if ((rv = PROXY_THREAD_UNLOCK(*balancer)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
                     "proxy: BALANCER: (%s). Unlock failed for pre_request",
                     (*balancer)->name);
    }
    if (!*worker) {
        runtime = find_best_worker(*balancer, r);
        if (!runtime) {
            ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
                         "proxy: BALANCER: (%s). All workers are in error state",
                         (*balancer)->name);

            return HTTP_SERVICE_UNAVAILABLE;
        }
        if ((*balancer)->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;
    }

    /* Add balancer/worker info to env. */
    apr_table_setn(r->subprocess_env,
                   "BALANCER_NAME", (*balancer)->name);
    apr_table_setn(r->subprocess_env,
                   "BALANCER_WORKER_NAME", (*worker)->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_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
                 "proxy: BALANCER (%s) worker (%s) rewritten to %s",
                 (*balancer)->name, (*worker)->name, *url);

    return access_status;
}

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

#if 0
    apr_status_t rv;

    if ((rv = PROXY_THREAD_LOCK(balancer)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
            "proxy: BALANCER: (%s). Lock failed for post_request",
            balancer->name);
        return HTTP_INTERNAL_SERVER_ERROR;
    }
    /* TODO: placeholder for post_request actions
     */

    if ((rv = PROXY_THREAD_UNLOCK(balancer)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
            "proxy: BALANCER: (%s). Unlock failed for post_request",
            balancer->name);
    }
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
                 "proxy_balancer_post_request for (%s)", balancer->name);

#endif

    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 it's
     * load factor will always be 1
     */
    if (balancer->workers->nelts == 1) {
        workers->s->lbstatus = workers->s->lbfactor = 1;
        return;
    }
    for (i = 0; i < balancer->workers->nelts; i++) {
        /* Update the status entries */
        workers[i].s->lbstatus = workers[i].s->lbfactor;
    }
}

/* post_config hook: */
static int balancer_init(apr_pool_t *p, apr_pool_t *plog,
                         apr_pool_t *ptemp, server_rec *s)
{
    void *data;
    const char *userdata_key = "mod_proxy_balancer_init";
    apr_uuid_t uuid;

    /* balancer_init() will be called twice during startup.  So, only
     * set up the static data the second time through. */
    apr_pool_userdata_get(&data, userdata_key, s->process->pool);
    if (!data) {
        apr_pool_userdata_set((const void *)1, userdata_key,
                               apr_pool_cleanup_null, s->process->pool);
        return OK;
    }

    /* Retrieve a UUID and store the nonce for the lifetime of
     * the process. */
    apr_uuid_get(&uuid);
    apr_uuid_format(balancer_nonce, &uuid);

    return OK;
}

/* Manages the loadfactors and member status
 */
static int balancer_handler(request_rec *r)
{
    void *sconf = r->server->module_config;
    proxy_server_conf *conf = (proxy_server_conf *)
        ap_get_module_config(sconf, &proxy_module);
    proxy_balancer *balancer, *bsel = NULL;
    proxy_worker *worker, *wsel = NULL;
    apr_table_t *params = apr_table_make(r->pool, 10);
    int access_status;
    int i, n;
    const char *name;

    /* is this for us? */
    if (strcmp(r->handler, "balancer-manager"))
        return DECLINED;
    r->allowed = (AP_METHOD_BIT << M_GET);
    if (r->method_number != M_GET)
        return DECLINED;

    if (r->args) {
        char *args = apr_pstrdup(r->pool, r->args);
        char *tok, *val;
        while (args && *args) {
            if ((val = ap_strchr(args, '='))) {
                *val++ = '\0';
                if ((tok = ap_strchr(val, '&')))
                    *tok++ = '\0';
                /*
                 * Special case: workers are allowed path information
                 */
                if ((access_status = ap_unescape_url(val)) != OK)
                    if (strcmp(args, "w") || (access_status !=  HTTP_NOT_FOUND))
                        return access_status;
                apr_table_setn(params, args, val);
                args = tok;
            }
            else
                return HTTP_BAD_REQUEST;
        }
    }
    
    /* Check that the supplied nonce matches this server's nonce;
     * otherwise ignore all parameters, to prevent a CSRF attack. */
    if ((name = apr_table_get(params, "nonce")) == NULL 
        || strcmp(balancer_nonce, name) != 0) {
        apr_table_clear(params);
    }

    if ((name = apr_table_get(params, "b")))
        bsel = ap_proxy_get_balancer(r->pool, conf,
            apr_pstrcat(r->pool, "balancer://", name, NULL));
    if ((name = apr_table_get(params, "w"))) {
        proxy_worker *ws;

        ws = ap_proxy_get_worker(r->pool, conf, name);
        if (bsel && ws) {
            worker = (proxy_worker *)bsel->workers->elts;
            for (n = 0; n < bsel->workers->nelts; n++) {
                if (strcasecmp(worker->name, ws->name) == 0) {
                    wsel = worker;
                    break;
                }
                ++worker;
            }
        }
    }
    /* First set the params */
    /*
     * Note that it is not possible set the proxy_balancer because it is not
     * in shared memory.
     */
    if (wsel) {
        const char *val;
        if ((val = apr_table_get(params, "lf"))) {
            int ival = atoi(val);
            if (ival >= 1 && ival <= 100) {
                wsel->s->lbfactor = ival;
                if (bsel)
                    recalc_factors(bsel);
            }
        }
        if ((val = apr_table_get(params, "wr"))) {
            if (strlen(val) && strlen(val) < PROXY_WORKER_MAX_ROUTE_SIZ)
                strcpy(wsel->s->route, val);
            else
                *wsel->s->route = '\0';
        }
        if ((val = apr_table_get(params, "rr"))) {
            if (strlen(val) && strlen(val) < PROXY_WORKER_MAX_ROUTE_SIZ)
                strcpy(wsel->s->redirect, val);
            else
                *wsel->s->redirect = '\0';
        }
        if ((val = apr_table_get(params, "dw"))) {
            if (!strcasecmp(val, "Disable"))
                wsel->s->status |= PROXY_WORKER_DISABLED;
            else if (!strcasecmp(val, "Enable"))
                wsel->s->status &= ~PROXY_WORKER_DISABLED;
        }
        if ((val = apr_table_get(params, "ls"))) {
            int ival = atoi(val);
            if (ival >= 0 && ival <= 99) {
                wsel->s->lbset = ival;
             }
        }

    }
    if (apr_table_get(params, "xml")) {
        ap_set_content_type(r, "text/xml");
        ap_rputs("<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n", r);
        ap_rputs("<httpd:manager xmlns:httpd=\"http://httpd.apache.org\">\n", r);
        ap_rputs("  <httpd:balancers>\n", r);
        balancer = (proxy_balancer *)conf->balancers->elts;
        for (i = 0; i < conf->balancers->nelts; i++) {
            ap_rputs("    <httpd:balancer>\n", r);
            ap_rvputs(r, "      <httpd:name>", balancer->name, "</httpd:name>\n", NULL);
            ap_rputs("      <httpd:workers>\n", r);
            worker = (proxy_worker *)balancer->workers->elts;
            for (n = 0; n < balancer->workers->nelts; n++) {
                ap_rputs("        <httpd:worker>\n", r);
                ap_rvputs(r, "          <httpd:scheme>", worker->scheme,
                          "</httpd:scheme>\n", NULL);
                ap_rvputs(r, "          <httpd:hostname>", worker->hostname,
                          "</httpd:hostname>\n", NULL);
               ap_rprintf(r, "          <httpd:loadfactor>%d</httpd:loadfactor>\n",
                          worker->s->lbfactor);
                ap_rputs("        </httpd:worker>\n", r);
                ++worker;
            }
            ap_rputs("      </httpd:workers>\n", r);