git.r.bdr.sh - rbdr/ngx_http_office_hours_filter_module/blob - ngx_http_office_hours_filter_module.c

   1 /*
   2  * Copyright 2018 Rubén Beltrán del Río
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the
   5  * License. You may obtain a copy of the License at
   6  *
   7  * http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
  10  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
  11  * specific language governing permissions and limitations under the License.
  12  */
  13
  14
  15 #include <ngx_config.h>
  16 #include <ngx_core.h>
  17 #include <ngx_http.h>
  18
  19 /*
  20  * Declarations
  21  */
  22
  23 /* Constants */
  24
  25 const ngx_uint_t WEEK_LENGTH = 7;
  26 const char * CLOSED_TOKEN = "closed";
  27 const ngx_str_t TIME_REGEX = ngx_string("([0-9]{1,2})(?:\\:([0-9]{2}))?\\-([0-9]{1,2})(?:\\:([0-9]{2}))?");
  28
  29 /* Main Configuration Structure */
  30
  31 typedef struct {
  32     ngx_array_t *office_hours;
  33 } ngx_http_office_hours_conf_t;
  34
  35 /* Lifecycle Functions For Module Context */
  36
  37 static void *ngx_http_office_hours_create_conf(ngx_conf_t * cf);
  38 static char *ngx_http_office_hours_merge_conf(ngx_conf_t * cf,
  39         void *parent, void *child);
  40 static ngx_int_t ngx_http_office_hours_init(ngx_conf_t * cf);
  41
  42 /* Configuration Handler */
  43
  44 static char *ngx_http_office_hours(ngx_conf_t * cf, ngx_command_t * cmd,
  45                                    void *conf);
  46
  47 /* Body Filter Storage */
  48
  49 static ngx_http_output_body_filter_pt ngx_http_next_body_filter;
  50
  51 /* Utility Functions */
  52 static ngx_uint_t ** parse_office_hours(ngx_array_t * office_hours);
  53 static ngx_uint_t * parse_office_hours_string(ngx_str_t office_hours);
  54 static ngx_flag_t within_office_hours(ngx_uint_t ** office_hours);
  55 static ngx_uint_t get_day_of_week(time_t time);
  56 static ngx_uint_t get_seconds_of_day(time_t time);
  57
  58 /* Compiled Regex */
  59 ngx_regex_compile_t rc;
  60
  61 /*
  62  * Module Definitions
  63  */
  64
  65 /* Module Directives */
  66
  67 static ngx_command_t ngx_http_office_hours_commands[] = {
  68     {
  69         ngx_string("office_hours"),
  70         NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_TAKE1 | NGX_CONF_TAKE2 | NGX_CONF_TAKE3 | NGX_CONF_TAKE4 | NGX_CONF_TAKE5 | NGX_CONF_TAKE6 | NGX_CONF_TAKE7,
  71         ngx_http_office_hours,
  72         NGX_HTTP_LOC_CONF_OFFSET,
  73         offsetof(ngx_http_office_hours_conf_t, office_hours),
  74         NULL
  75     },
  76
  77     ngx_null_command
  78 };
  79
  80
  81 /* Module Context */
  82
  83 static ngx_http_module_t ngx_http_office_hours_filter_module_ctx = {
  84     NULL,                       /* Preconfiguration */
  85     ngx_http_office_hours_init, /* Postconfiguration */
  86
  87     NULL,                       /* Create main configuration */
  88     NULL,                       /* Initialize main configuration */
  89
  90     NULL,                       /* Create server configuration */
  91     NULL,                       /* Merge server configuration */
  92
  93     ngx_http_office_hours_create_conf,  /* Create location configuration */
  94     ngx_http_office_hours_merge_conf    /* Merge location configuration */
  95 };
  96
  97
  98 /* Module Definition */
  99
 100 ngx_module_t ngx_http_office_hours_filter_module = {
 101     NGX_MODULE_V1,              //Module Version
 102     &ngx_http_office_hours_filter_module_ctx,   //Module context
 103     ngx_http_office_hours_commands,     //Module commands
 104     NGX_HTTP_MODULE,            //Module Type
 105     NULL,                       //Initialize Master
 106     NULL,                       //Initialize Module
 107     NULL,                       //Initialize Process
 108     NULL,                       //Initialize Thread
 109     NULL,                       //Exit Thread
 110     NULL,                       //Exit Process
 111     NULL,                       //Exit Master
 112     NGX_MODULE_V1_PADDING
 113 };
 114
 115
 116 /*
 117  * Main Body Filter
 118  * If the current time is within office hours, it goes to the next
 119  * handler. Otherwise it returns 403 and the office hour listing.
 120  */
 121
 122 static ngx_int_t
 123 ngx_http_office_hours_body_filter(ngx_http_request_t * r, ngx_chain_t * in)
 124 {
 125
 126     ngx_uint_t ** parsed_office_hours;
 127     ngx_http_office_hours_conf_t *conf;
 128
 129     conf =
 130         ngx_http_get_module_loc_conf(r,
 131                                      ngx_http_office_hours_filter_module);
 132
 133
 134     if (conf->office_hours == NULL) {
 135         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 136                       "Office hours disabled");
 137         return ngx_http_next_body_filter(r, in);
 138     }
 139
 140     parsed_office_hours = parse_office_hours(conf->office_hours);
 141
 142     if (within_office_hours(parsed_office_hours)) {
 143         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 144                       "Within office hours");
 145         return ngx_http_next_body_filter(r, in);
 146     }
 147
 148     ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 149                   "Outside office hours");
 150
 151     r->keepalive = 0;
 152     return NGX_HTTP_FORBIDDEN;
 153 }
 154
 155 /*
 156  * Callback for `office_hours ` directive
 157  * Reads the configuration loaded from the config file(cf)
 158  * And writes it to the right place in the module configuration(conf)
 159  */
 160
 161 static char *ngx_http_office_hours(ngx_conf_t * cf, ngx_command_t * cmd,
 162                                    void *conf)
 163 {
 164
 165     char *conf_structure = conf;
 166
 167     ngx_str_t *hours, *value;
 168     ngx_array_t **office_hours;
 169     ngx_uint_t i;
 170
 171     /* Gets the array from the config structure using the defined
 172      * offset, and if the pointer is unset it creates a new one.
 173      * (The first element is the directive itself, so we should be
 174      * offset by 1)
 175      */
 176     office_hours = (ngx_array_t **) (conf_structure + cmd->offset);
 177
 178     if (*office_hours == NGX_CONF_UNSET_PTR) {
 179         *office_hours = ngx_array_create(cf->pool, cf->args->nelts - 1,
 180                                          sizeof(ngx_str_t));
 181
 182         if (*office_hours == NULL) {
 183             return NGX_CONF_ERROR;
 184         }
 185     }
 186     value = cf->args->elts;
 187
 188     for (i = 1; i < cf->args->nelts; ++i) {
 189         hours = ngx_array_push(*office_hours);
 190         if (hours == NULL) {
 191             return NGX_CONF_ERROR;
 192         }
 193         *hours = value[i];
 194     }
 195
 196     return NGX_CONF_OK;
 197 }
 198
 199
 200 /*
 201  * Config Creator
 202  * Initializes the configuration structure
 203  */
 204
 205 static void *ngx_http_office_hours_create_conf(ngx_conf_t * cf)
 206 {
 207
 208     ngx_http_office_hours_conf_t *conf;
 209
 210     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_office_hours_conf_t));
 211
 212     if (conf == NULL) {
 213         return NULL;
 214     }
 215     conf->office_hours = NGX_CONF_UNSET_PTR;
 216
 217     return conf;
 218 }
 219
 220 /*
 221  * Merge Config Values
 222  * Sets the defaults for the configuration and merges
 223  * with other configurations
 224  */
 225
 226 static char *ngx_http_office_hours_merge_conf(ngx_conf_t * cf,
 227         void *parent, void *child)
 228 {
 229
 230     ngx_http_office_hours_conf_t *prev = parent;
 231     ngx_http_office_hours_conf_t *conf = child;
 232
 233     ngx_conf_merge_ptr_value(conf->office_hours, prev->office_hours, NULL);
 234
 235     return NGX_CONF_OK;
 236 }
 237
 238 /*
 239  * Postconfig Initialization Handler
 240  * Sets the request filter at the top of the chain
 241  */
 242
 243 static ngx_int_t ngx_http_office_hours_init(ngx_conf_t * cf)
 244 {
 245
 246     ngx_http_next_body_filter = ngx_http_top_body_filter;
 247     ngx_http_top_body_filter = ngx_http_office_hours_body_filter;
 248
 249     rc.pattern = TIME_REGEX;
 250     rc.pool = cf->pool;
 251     if (ngx_regex_compile(&rc) != NGX_OK) {
 252         return NGX_ERROR;
 253     }
 254
 255     return NGX_OK;
 256 }
 257
 258 /*
 259  * Parse the office hour strings in the configuration file
 260  * to fill out the hours array (in seconds)
 261  */
 262
 263 static ngx_uint_t ** parse_office_hours(ngx_array_t * office_hours)
 264 {
 265
 266     ngx_str_t *hours;
 267     ngx_uint_t ** parsed_office_hours;
 268     ngx_uint_t i, j;
 269
 270     parsed_office_hours = malloc(7 * sizeof(ngx_uint_t *));
 271
 272     hours = office_hours->elts;
 273
 274     /*
 275      * On the configuration file, the leftmost element
 276      * always applies to all remaining days, all others
 277      * are read from right to left. So first we will apply
 278      * the initial override, and then iterate based on the
 279      * number of overrides
 280      */
 281
 282     for (i = 0; i < WEEK_LENGTH + 1 - office_hours->nelts; ++i) {
 283         parsed_office_hours[i] = parse_office_hours_string(hours[0]);
 284     }
 285
 286     for (i = 1; i < office_hours->nelts; ++i) {
 287         j = WEEK_LENGTH - office_hours->nelts + i;
 288         parsed_office_hours[j] = parse_office_hours_string(hours[i]);
 289     }
 290
 291     return parsed_office_hours;
 292 }
 293
 294 /*
 295  * Given a time string or the closed token, return a tuple
 296  * of numbers representing opening and closing hours
 297  */
 298
 299 static ngx_uint_t * parse_office_hours_string(ngx_str_t office_hours)
 300 {
 301
 302     int captures[(1 + 4) * 3];
 303     ngx_int_t n;
 304     ngx_uint_t * parsed_hours;
 305
 306     parsed_hours = malloc(2 * sizeof(ngx_uint_t));
 307
 308     if(ngx_strcmp(office_hours.data, CLOSED_TOKEN) == 0) {
 309         parsed_hours[0] = 0;
 310         parsed_hours[1] = 0;
 311         return parsed_hours;
 312     }
 313
 314     n = ngx_regex_exec(rc.regex, &office_hours, captures, (1 + 4) * 3);
 315
 316     if (n >= 0) {
 317         /* Opening Hours */
 318
 319         parsed_hours[0] = 60 * 60 * ngx_atoi(&office_hours.data[captures[2]], captures[3] - captures[2]);
 320         parsed_hours[0] = parsed_hours[0] + 60 * ngx_atoi(&office_hours.data[captures[4]], captures[5] - captures[4]);
 321
 322         parsed_hours[1] = 60 * 60 * ngx_atoi(&office_hours.data[captures[6]], captures[7] - captures[6]);
 323         parsed_hours[1] = parsed_hours[1] + 60 * ngx_atoi(&office_hours.data[captures[8]], captures[9] - captures[8]);
 324
 325         return parsed_hours;
 326     }
 327
 328     /* Non-matching strings count as open */
 329
 330     parsed_hours[0] = 0;
 331     parsed_hours[1] = 86400;
 332     return parsed_hours;
 333 }
 334
 335 /*
 336  * Given an office hours array, it returns whether or not
 337  * it is currently within office hours.
 338  */
 339
 340 static ngx_flag_t within_office_hours(ngx_uint_t ** office_hours)
 341 {
 342
 343     time_t now;
 344     ngx_uint_t day_of_week, seconds_of_day;
 345     ngx_uint_t * current_hours;
 346
 347     ngx_time_update();
 348     now = ngx_time();
 349     day_of_week = get_day_of_week(now);
 350     seconds_of_day = get_seconds_of_day(now);
 351     current_hours = office_hours[day_of_week];
 352
 353     return seconds_of_day >= current_hours[0] && seconds_of_day <= current_hours[1];
 354 }
 355
 356 /*
 357  * Calculate the day of the week given a timestamp
 358  */
 359 static ngx_uint_t get_day_of_week(time_t time)
 360 {
 361
 362     /* Epoch was thursday, so add 3 so we start on monday */
 363     return (time / 86400 + 3) % 7;
 364 }
 365
 366 /*
 367  * Calculate the number of seconds elapsed today
 368  */
 369 static ngx_uint_t get_seconds_of_day(time_t time)
 370 {
 371
 372     return time - (time / 86400) * 86400;
 373 }