view src/event/ngx_event_posted.c @ 7386:9200b41db765 stable-1.14

HTTP/2: limit the number of idle state switches. An attack that continuously switches HTTP/2 connection between idle and active states can result in excessive CPU usage. This is because when a connection switches to the idle state, all of its memory pool caches are freed. This change limits the maximum allowed number of idle state switches to 10 * http2_max_requests (i.e., 10000 by default). This limits possible CPU usage in one connection, and also imposes a limit on the maximum lifetime of a connection. Initially reported by Gal Goldshtein from F5 Networks.
author Ruslan Ermilov <ru@nginx.com>
date Tue, 06 Nov 2018 16:29:49 +0300
parents 3f5f0ab59b35
children 9d2ad2fb4423
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


ngx_queue_t  ngx_posted_accept_events;
ngx_queue_t  ngx_posted_events;


void
ngx_event_process_posted(ngx_cycle_t *cycle, ngx_queue_t *posted)
{
    ngx_queue_t  *q;
    ngx_event_t  *ev;

    while (!ngx_queue_empty(posted)) {

        q = ngx_queue_head(posted);
        ev = ngx_queue_data(q, ngx_event_t, queue);

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                      "posted event %p", ev);

        ngx_delete_posted_event(ev);

        ev->handler(ev);
    }
}