view src/http/modules/ngx_http_empty_gif_module.c @ 9299:2706b60dc225 default tip

Core: error logging rate limiting. With this change, error logging to files can be rate-limited with the "rate=" parameter. The parameter specifies allowed log messages rate to a particular file (per worker), in messages per second (m/s). By default, "rate=1000m/s" is used. Rate limiting is implemented using the "leaky bucket" method, similarly to the limit_req module. Maximum burst size is set to the number of log messages per second for each severity level, so "error" messages are logged even if the rate limit is hit by "info" messages (but not vice versa). When the limit is reached for a particular level, the "too many log messages, limiting" message is logged at this level. If debug logging is enabled, either for the particular log file or for the particular connection, rate limiting is not used.
author Maxim Dounin <mdounin@mdounin.ru>
date Tue, 25 Jun 2024 22:58:56 +0300
parents d620f497c50f
children
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */

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


static char *ngx_http_empty_gif(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);

static ngx_command_t  ngx_http_empty_gif_commands[] = {

    { ngx_string("empty_gif"),
      NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS,
      ngx_http_empty_gif,
      0,
      0,
      NULL },

      ngx_null_command
};


/* the minimal single pixel transparent GIF, 43 bytes */

static u_char  ngx_empty_gif[] = {

    'G', 'I', 'F', '8', '9', 'a',  /* header                                 */

                                   /* logical screen descriptor              */
    0x01, 0x00,                    /* logical screen width                   */
    0x01, 0x00,                    /* logical screen height                  */
    0x80,                          /* global 1-bit color table               */
    0x01,                          /* background color #1                    */
    0x00,                          /* no aspect ratio                        */

                                   /* global color table                     */
    0x00, 0x00, 0x00,              /* #0: black                              */
    0xff, 0xff, 0xff,              /* #1: white                              */

                                   /* graphic control extension              */
    0x21,                          /* extension introducer                   */
    0xf9,                          /* graphic control label                  */
    0x04,                          /* block size                             */
    0x01,                          /* transparent color is given,            */
                                   /*     no disposal specified,             */
                                   /*     user input is not expected         */
    0x00, 0x00,                    /* delay time                             */
    0x01,                          /* transparent color #1                   */
    0x00,                          /* block terminator                       */

                                   /* image descriptor                       */
    0x2c,                          /* image separator                        */
    0x00, 0x00,                    /* image left position                    */
    0x00, 0x00,                    /* image top position                     */
    0x01, 0x00,                    /* image width                            */
    0x01, 0x00,                    /* image height                           */
    0x00,                          /* no local color table, no interlaced    */

                                   /* table based image data                 */
    0x02,                          /* LZW minimum code size,                 */
                                   /*     must be at least 2-bit             */
    0x02,                          /* block size                             */
    0x4c, 0x01,                    /* compressed bytes 01_001_100, 0000000_1 */
                                   /* 100: clear code                        */
                                   /* 001: 1                                 */
                                   /* 101: end of information code           */
    0x00,                          /* block terminator                       */

    0x3B                           /* trailer                                */
};


static ngx_http_module_t  ngx_http_empty_gif_module_ctx = {
    NULL,                          /* preconfiguration */
    NULL,                          /* postconfiguration */

    NULL,                          /* create main configuration */
    NULL,                          /* init main configuration */

    NULL,                          /* create server configuration */
    NULL,                          /* merge server configuration */

    NULL,                          /* create location configuration */
    NULL                           /* merge location configuration */
};


ngx_module_t  ngx_http_empty_gif_module = {
    NGX_MODULE_V1,
    &ngx_http_empty_gif_module_ctx, /* module context */
    ngx_http_empty_gif_commands,   /* module directives */
    NGX_HTTP_MODULE,               /* module type */
    NULL,                          /* init master */
    NULL,                          /* init module */
    NULL,                          /* init process */
    NULL,                          /* init thread */
    NULL,                          /* exit thread */
    NULL,                          /* exit process */
    NULL,                          /* exit master */
    NGX_MODULE_V1_PADDING
};


static ngx_str_t  ngx_http_gif_type = ngx_string("image/gif");


static ngx_int_t
ngx_http_empty_gif_handler(ngx_http_request_t *r)
{
    ngx_http_complex_value_t  cv;

    if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) {
        return NGX_HTTP_NOT_ALLOWED;
    }

    ngx_memzero(&cv, sizeof(ngx_http_complex_value_t));

    cv.value.len = sizeof(ngx_empty_gif);
    cv.value.data = ngx_empty_gif;
    r->headers_out.last_modified_time = 23349600;

    return ngx_http_send_response(r, NGX_HTTP_OK, &ngx_http_gif_type, &cv);
}


static char *
ngx_http_empty_gif(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_core_loc_conf_t  *clcf;

    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
    clcf->handler = ngx_http_empty_gif_handler;

    return NGX_CONF_OK;
}