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view src/http/modules/ngx_http_empty_gif_module.c @ 4248:2fad4d19ea4b stable-1.0

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Merging r4151, r4152, r4177: HTTP cache related fixes: *) Cache: fix for sending of empty responses. Revert wrong fix for empty responses introduced in 0.8.31 and apply new one, rewritten to match things done by static module as close as possible. *) Cache: fix for sending of stale responses. For normal cached responses ngx_http_cache_send() sends last buffer and then request finalized via ngx_http_finalize_request() call, i.e. everything is ok. But for stale responses (i.e. when upstream died, but we have something in cache) the same ngx_http_cache_send() sends last buffer, but then in ngx_http_upstream_finalize_request() another last buffer is send. This causes duplicate final chunk to appear if chunked encoding is used (and resulting problems with keepalive connections and so on). Fix this by not sending in ngx_http_upstream_finalize_request() another last buffer if we know response was from cache. *) Fixed cache bypass caching of non-cacheable replies (ticket #21). If cache was bypassed with proxy_cache_bypass, cache-controlling headers (Cache-Control, Expires) wasn't considered and response was cached even if it was actually non-cacheable. Patch by John Ferlito.
author Igor Sysoev <igor@sysoev.ru>
date Tue, 01 Nov 2011 13:49:31 +0000
parents b79dbadb3d5e
children d620f497c50f
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 */

#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;
}