release/src/router/nginx/src/http/modules/ngx_http_empty_gif_module.c

   1
   2 /*
   3  * Copyright (C) Igor Sysoev
   4  * Copyright (C) Nginx, Inc.
   5  */
   6
   7 #include <ngx_config.h>
   8 #include <ngx_core.h>
   9 #include <ngx_http.h>
  10
  11
  12 static char *ngx_http_empty_gif(ngx_conf_t *cf, ngx_command_t *cmd,
  13     void *conf);
  14
  15 static ngx_command_t  ngx_http_empty_gif_commands[] = {
  16
  17     { ngx_string("empty_gif"),
  18       NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS,
  19       ngx_http_empty_gif,
  20       0,
  21       0,
  22       NULL },
  23
  24       ngx_null_command
  25 };
  26
  27
  28 /* the minimal single pixel transparent GIF, 43 bytes */
  29
  30 static u_char  ngx_empty_gif[] = {
  31
  32     'G', 'I', 'F', '8', '9', 'a',  /* header                                 */
  33
  34                                    /* logical screen descriptor              */
  35     0x01, 0x00,                    /* logical screen width                   */
  36     0x01, 0x00,                    /* logical screen height                  */
  37     0x80,                          /* global 1-bit color table               */
  38     0x01,                          /* background color #1                    */
  39     0x00,                          /* no aspect ratio                        */
  40
  41                                    /* global color table                     */
  42     0x00, 0x00, 0x00,              /* #0: black                              */
  43     0xff, 0xff, 0xff,              /* #1: white                              */
  44
  45                                    /* graphic control extension              */
  46     0x21,                          /* extension introducer                   */
  47     0xf9,                          /* graphic control label                  */
  48     0x04,                          /* block size                             */
  49     0x01,                          /* transparent color is given,            */
  50                                    /*     no disposal specified,             */
  51                                    /*     user input is not expected         */
  52     0x00, 0x00,                    /* delay time                             */
  53     0x01,                          /* transparent color #1                   */
  54     0x00,                          /* block terminator                       */
  55
  56                                    /* image descriptor                       */
  57     0x2c,                          /* image separator                        */
  58     0x00, 0x00,                    /* image left position                    */
  59     0x00, 0x00,                    /* image top position                     */
  60     0x01, 0x00,                    /* image width                            */
  61     0x01, 0x00,                    /* image height                           */
  62     0x00,                          /* no local color table, no interlaced    */
  63
  64                                    /* table based image data                 */
  65     0x02,                          /* LZW minimum code size,                 */
  66                                    /*     must be at least 2-bit             */
  67     0x02,                          /* block size                             */
  68     0x4c, 0x01,                    /* compressed bytes 01_001_100, 0000000_1 */
  69                                    /* 100: clear code                        */
  70                                    /* 001: 1                                 */
  71                                    /* 101: end of information code           */
  72     0x00,                          /* block terminator                       */
  73
  74     0x3B                           /* trailer                                */
  75 };
  76
  77
  78 static ngx_http_module_t  ngx_http_empty_gif_module_ctx = {
  79     NULL,                          /* preconfiguration */
  80     NULL,                          /* postconfiguration */
  81
  82     NULL,                          /* create main configuration */
  83     NULL,                          /* init main configuration */
  84
  85     NULL,                          /* create server configuration */
  86     NULL,                          /* merge server configuration */
  87
  88     NULL,                          /* create location configuration */
  89     NULL                           /* merge location configuration */
  90 };
  91
  92
  93 ngx_module_t  ngx_http_empty_gif_module = {
  94     NGX_MODULE_V1,
  95     &ngx_http_empty_gif_module_ctx, /* module context */
  96     ngx_http_empty_gif_commands,   /* module directives */
  97     NGX_HTTP_MODULE,               /* module type */
  98     NULL,                          /* init master */
  99     NULL,                          /* init module */
 100     NULL,                          /* init process */
 101     NULL,                          /* init thread */
 102     NULL,                          /* exit thread */
 103     NULL,                          /* exit process */
 104     NULL,                          /* exit master */
 105     NGX_MODULE_V1_PADDING
 106 };
 107
 108
 109 static ngx_str_t  ngx_http_gif_type = ngx_string("image/gif");
 110
 111
 112 static ngx_int_t
 113 ngx_http_empty_gif_handler(ngx_http_request_t *r)
 114 {
 115     ngx_http_complex_value_t  cv;
 116
 117     if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) {
 118         return NGX_HTTP_NOT_ALLOWED;
 119     }
 120
 121     ngx_memzero(&cv, sizeof(ngx_http_complex_value_t));
 122
 123     cv.value.len = sizeof(ngx_empty_gif);
 124     cv.value.data = ngx_empty_gif;
 125     r->headers_out.last_modified_time = 23349600;
 126
 127     return ngx_http_send_response(r, NGX_HTTP_OK, &ngx_http_gif_type, &cv);
 128 }
 129
 130
 131 static char *
 132 ngx_http_empty_gif(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 133 {
 134     ngx_http_core_loc_conf_t  *clcf;
 135
 136     clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
 137     clcf->handler = ngx_http_empty_gif_handler;
 138
 139     return NGX_CONF_OK;
 140 }