app/nginx/src/http/modules/ngx_http_not_modified_filter_module.c

   1
   2 /*
   3  * Copyright (C) Igor Sysoev
   4  * Copyright (C) Nginx, Inc.
   5  */
   6
   7
   8 #include <ngx_config.h>
   9 #include <ngx_core.h>
  10 #include <ngx_http.h>
  11
  12
  13 static ngx_uint_t ngx_http_test_if_unmodified(ngx_http_request_t *r);
  14 static ngx_uint_t ngx_http_test_if_modified(ngx_http_request_t *r);
  15 static ngx_uint_t ngx_http_test_if_match(ngx_http_request_t *r,
  16     ngx_table_elt_t *header, ngx_uint_t weak);
  17 static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf);
  18
  19
  20 static ngx_http_module_t  ngx_http_not_modified_filter_module_ctx = {
  21     NULL,                                  /* preconfiguration */
  22     ngx_http_not_modified_filter_init,     /* postconfiguration */
  23
  24     NULL,                                  /* create main configuration */
  25     NULL,                                  /* init main configuration */
  26
  27     NULL,                                  /* create server configuration */
  28     NULL,                                  /* merge server configuration */
  29
  30     NULL,                                  /* create location configuration */
  31     NULL                                   /* merge location configuration */
  32 };
  33
  34
  35 ngx_module_t  ngx_http_not_modified_filter_module = {
  36     NGX_MODULE_V1,
  37     &ngx_http_not_modified_filter_module_ctx, /* module context */
  38     NULL,                                  /* module directives */
  39     NGX_HTTP_MODULE,                       /* module type */
  40     NULL,                                  /* init master */
  41     NULL,                                  /* init module */
  42     NULL,                                  /* init process */
  43     NULL,                                  /* init thread */
  44     NULL,                                  /* exit thread */
  45     NULL,                                  /* exit process */
  46     NULL,                                  /* exit master */
  47     NGX_MODULE_V1_PADDING
  48 };
  49
  50
  51 static ngx_http_output_header_filter_pt  ngx_http_next_header_filter;
  52
  53
  54 static ngx_int_t
  55 ngx_http_not_modified_header_filter(ngx_http_request_t *r)
  56 {
  57     if (r->headers_out.status != NGX_HTTP_OK
  58         || r != r->main
  59         || r->disable_not_modified)
  60     {
  61         return ngx_http_next_header_filter(r);
  62     }
  63
  64     if (r->headers_in.if_unmodified_since
  65         && !ngx_http_test_if_unmodified(r))
  66     {
  67         return ngx_http_filter_finalize_request(r, NULL,
  68                                                 NGX_HTTP_PRECONDITION_FAILED);
  69     }
  70
  71     if (r->headers_in.if_match
  72         && !ngx_http_test_if_match(r, r->headers_in.if_match, 0))
  73     {
  74         return ngx_http_filter_finalize_request(r, NULL,
  75                                                 NGX_HTTP_PRECONDITION_FAILED);
  76     }
  77
  78     if (r->headers_in.if_modified_since || r->headers_in.if_none_match) {
  79
  80         if (r->headers_in.if_modified_since
  81             && ngx_http_test_if_modified(r))
  82         {
  83             return ngx_http_next_header_filter(r);
  84         }
  85
  86         if (r->headers_in.if_none_match
  87             && !ngx_http_test_if_match(r, r->headers_in.if_none_match, 1))
  88         {
  89             return ngx_http_next_header_filter(r);
  90         }
  91
  92         /* not modified */
  93
  94         r->headers_out.status = NGX_HTTP_NOT_MODIFIED;
  95         r->headers_out.status_line.len = 0;
  96         r->headers_out.content_type.len = 0;
  97         ngx_http_clear_content_length(r);
  98         ngx_http_clear_accept_ranges(r);
  99
 100         if (r->headers_out.content_encoding) {
 101             r->headers_out.content_encoding->hash = 0;
 102             r->headers_out.content_encoding = NULL;
 103         }
 104
 105         return ngx_http_next_header_filter(r);
 106     }
 107
 108     return ngx_http_next_header_filter(r);
 109 }
 110
 111
 112 static ngx_uint_t
 113 ngx_http_test_if_unmodified(ngx_http_request_t *r)
 114 {
 115     time_t  iums;
 116
 117     if (r->headers_out.last_modified_time == (time_t) -1) {
 118         return 0;
 119     }
 120
 121     iums = ngx_parse_http_time(r->headers_in.if_unmodified_since->value.data,
 122                                r->headers_in.if_unmodified_since->value.len);
 123
 124     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
 125                  "http iums:%T lm:%T", iums, r->headers_out.last_modified_time);
 126
 127     if (iums >= r->headers_out.last_modified_time) {
 128         return 1;
 129     }
 130
 131     return 0;
 132 }
 133
 134
 135 static ngx_uint_t
 136 ngx_http_test_if_modified(ngx_http_request_t *r)
 137 {
 138     time_t                     ims;
 139     ngx_http_core_loc_conf_t  *clcf;
 140
 141     if (r->headers_out.last_modified_time == (time_t) -1) {
 142         return 1;
 143     }
 144
 145     clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
 146
 147     if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) {
 148         return 1;
 149     }
 150
 151     ims = ngx_parse_http_time(r->headers_in.if_modified_since->value.data,
 152                               r->headers_in.if_modified_since->value.len);
 153
 154     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
 155                    "http ims:%T lm:%T", ims, r->headers_out.last_modified_time);
 156
 157     if (ims == r->headers_out.last_modified_time) {
 158         return 0;
 159     }
 160
 161     if (clcf->if_modified_since == NGX_HTTP_IMS_EXACT
 162         || ims < r->headers_out.last_modified_time)
 163     {
 164         return 1;
 165     }
 166
 167     return 0;
 168 }
 169
 170
 171 static ngx_uint_t
 172 ngx_http_test_if_match(ngx_http_request_t *r, ngx_table_elt_t *header,
 173     ngx_uint_t weak)
 174 {
 175     u_char     *start, *end, ch;
 176     ngx_str_t   etag, *list;
 177
 178     list = &header->value;
 179
 180     if (list->len == 1 && list->data[0] == '*') {
 181         return 1;
 182     }
 183
 184     if (r->headers_out.etag == NULL) {
 185         return 0;
 186     }
 187
 188     etag = r->headers_out.etag->value;
 189
 190     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
 191                    "http im:\"%V\" etag:%V", list, &etag);
 192
 193     if (weak
 194         && etag.len > 2
 195         && etag.data[0] == 'W'
 196         && etag.data[1] == '/')
 197     {
 198         etag.len -= 2;
 199         etag.data += 2;
 200     }
 201
 202     start = list->data;
 203     end = list->data + list->len;
 204
 205     while (start < end) {
 206
 207         if (weak
 208             && end - start > 2
 209             && start[0] == 'W'
 210             && start[1] == '/')
 211         {
 212             start += 2;
 213         }
 214
 215         if (etag.len > (size_t) (end - start)) {
 216             return 0;
 217         }
 218
 219         if (ngx_strncmp(start, etag.data, etag.len) != 0) {
 220             goto skip;
 221         }
 222
 223         start += etag.len;
 224
 225         while (start < end) {
 226             ch = *start;
 227
 228             if (ch == ' ' || ch == '\t') {
 229                 start++;
 230                 continue;
 231             }
 232
 233             break;
 234         }
 235
 236         if (start == end || *start == ',') {
 237             return 1;
 238         }
 239
 240     skip:
 241
 242         while (start < end && *start != ',') { start++; }
 243         while (start < end) {
 244             ch = *start;
 245
 246             if (ch == ' ' || ch == '\t' || ch == ',') {
 247                 start++;
 248                 continue;
 249             }
 250
 251             break;
 252         }
 253     }
 254
 255     return 0;
 256 }
 257
 258
 259 static ngx_int_t
 260 ngx_http_not_modified_filter_init(ngx_conf_t *cf)
 261 {
 262     ngx_http_next_header_filter = ngx_http_top_header_filter;
 263     ngx_http_top_header_filter = ngx_http_not_modified_header_filter;
 264
 265     return NGX_OK;
 266 }