nginx/src/http/modules/ngx_http_not_modified_filter_module.c

   1
   2 /*
   3  * Copyright (C) Igor Sysoev
   4  */
   5
   6
   7 #include <ngx_config.h>
   8 #include <ngx_core.h>
   9 #include <ngx_http.h>
  10
  11
  12
  13 static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf);
  14
  15
  16 static ngx_http_module_t  ngx_http_not_modified_filter_module_ctx = {
  17     NULL,                                  /* preconfiguration */
  18     ngx_http_not_modified_filter_init,     /* postconfiguration */
  19
  20     NULL,                                  /* create main configuration */
  21     NULL,                                  /* init main configuration */
  22
  23     NULL,                                  /* create server configuration */
  24     NULL,                                  /* merge server configuration */
  25
  26     NULL,                                  /* create location configuration */
  27     NULL                                   /* merge location configuration */
  28 };
  29
  30
  31 ngx_module_t  ngx_http_not_modified_filter_module = {
  32     NGX_MODULE_V1,
  33     &ngx_http_not_modified_filter_module_ctx, /* module context */
  34     NULL,                                  /* module directives */
  35     NGX_HTTP_MODULE,                       /* module type */
  36     NULL,                                  /* init master */
  37     NULL,                                  /* init module */
  38     NULL,                                  /* init process */
  39     NULL,                                  /* init thread */
  40     NULL,                                  /* exit thread */
  41     NULL,                                  /* exit process */
  42     NULL,                                  /* exit master */
  43     NGX_MODULE_V1_PADDING
  44 };
  45
  46
  47 static ngx_http_output_header_filter_pt  ngx_http_next_header_filter;
  48
  49
  50 static
  51 ngx_int_t ngx_http_not_modified_header_filter(ngx_http_request_t *r)
  52 {
  53     time_t                     ims;
  54     ngx_http_core_loc_conf_t  *clcf;
  55
  56     if (r->headers_out.status != NGX_HTTP_OK
  57         || r != r->main
  58         || r->headers_in.if_modified_since == NULL
  59         || r->headers_out.last_modified_time == -1)
  60     {
  61         return ngx_http_next_header_filter(r);
  62     }
  63
  64     clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
  65
  66     if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) {
  67         return ngx_http_next_header_filter(r);
  68     }
  69
  70     ims = ngx_http_parse_time(r->headers_in.if_modified_since->value.data,
  71                               r->headers_in.if_modified_since->value.len);
  72
  73     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
  74                    "http ims:%d lm:%d", ims, r->headers_out.last_modified_time);
  75
  76     if (ims != r->headers_out.last_modified_time) {
  77
  78         if (clcf->if_modified_since == NGX_HTTP_IMS_EXACT
  79             || ims < r->headers_out.last_modified_time)
  80         {
  81             return ngx_http_next_header_filter(r);
  82         }
  83     }
  84
  85     r->headers_out.status = NGX_HTTP_NOT_MODIFIED;
  86     r->headers_out.content_type.len = 0;
  87     ngx_http_clear_content_length(r);
  88     ngx_http_clear_accept_ranges(r);
  89
  90     return ngx_http_next_header_filter(r);
  91 }
  92
  93
  94 static
  95 ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf)
  96 {
  97     ngx_http_next_header_filter = ngx_http_top_header_filter;
  98     ngx_http_top_header_filter = ngx_http_not_modified_header_filter;
  99
 100     return NGX_OK;
 101 }