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 static ngx_uint_t parse_number(ngx_str_t string, ngx_uint_t start, ngx_uint_t end);
  58
  59 /* Compiled Regex */
  60 ngx_regex_compile_t rc;
  61
  62 /*
  63  * Module Definitions
  64  */
  65
  66 /* Module Directives */
  67
  68 static ngx_command_t ngx_http_office_hours_commands[] = {
  69     {
  70         ngx_string("office_hours"),
  71         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,
  72         ngx_http_office_hours,
  73         NGX_HTTP_LOC_CONF_OFFSET,
  74         offsetof(ngx_http_office_hours_conf_t, office_hours),
  75         NULL
  76     },
  77
  78     ngx_null_command
  79 };
  80
  81
  82 /* Module Context */
  83
  84 static ngx_http_module_t ngx_http_office_hours_filter_module_ctx = {
  85     NULL,                       /* Preconfiguration */
  86     ngx_http_office_hours_init, /* Postconfiguration */
  87
  88     NULL,                       /* Create main configuration */
  89     NULL,                       /* Initialize main configuration */
  90
  91     NULL,                       /* Create server configuration */
  92     NULL,                       /* Merge server configuration */
  93
  94     ngx_http_office_hours_create_conf,  /* Create location configuration */
  95     ngx_http_office_hours_merge_conf    /* Merge location configuration */
  96 };
  97
  98
  99 /* Module Definition */
 100
 101 ngx_module_t ngx_http_office_hours_filter_module = {
 102     NGX_MODULE_V1,              //Module Version
 103     &ngx_http_office_hours_filter_module_ctx,   //Module context
 104     ngx_http_office_hours_commands,     //Module commands
 105     NGX_HTTP_MODULE,            //Module Type
 106     NULL,                       //Initialize Master
 107     NULL,                       //Initialize Module
 108     NULL,                       //Initialize Process
 109     NULL,                       //Initialize Thread
 110     NULL,                       //Exit Thread
 111     NULL,                       //Exit Process
 112     NULL,                       //Exit Master
 113     NGX_MODULE_V1_PADDING
 114 };
 115
 116
 117 /*
 118  * Main Body Filter
 119  * If the current time is within office hours, it goes to the next
 120  * handler. Otherwise it returns 403 and the office hour listing.
 121  */
 122
 123 static ngx_int_t
 124 ngx_http_office_hours_body_filter(ngx_http_request_t * r, ngx_chain_t * in)
 125 {
 126
 127     ngx_uint_t ** parsed_office_hours;
 128     ngx_http_office_hours_conf_t *conf;
 129
 130     conf =
 131         ngx_http_get_module_loc_conf(r,
 132                                      ngx_http_office_hours_filter_module);
 133
 134
 135     if (conf->office_hours == NULL) {
 136         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 137                       "Office hours disabled");
 138         return ngx_http_next_body_filter(r, in);
 139     }
 140
 141     parsed_office_hours = parse_office_hours(conf->office_hours);
 142
 143     if (within_office_hours(parsed_office_hours)) {
 144         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 145                       "Within office hours");
 146         return ngx_http_next_body_filter(r, in);
 147     }
 148
 149     ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 150                   "Outside office hours");
 151
 152     r->keepalive = 0;
 153     return NGX_HTTP_FORBIDDEN;
 154 }
 155
 156 /*
 157  * Callback for `office_hours ` directive
 158  * Reads the configuration loaded from the config file(cf)
 159  * And writes it to the right place in the module configuration(conf)
 160  */
 161
 162 static char *ngx_http_office_hours(ngx_conf_t * cf, ngx_command_t * cmd,
 163                                    void *conf)
 164 {
 165
 166     char *conf_structure = conf;
 167
 168     ngx_str_t *hours, *value;
 169     ngx_array_t **office_hours;
 170     ngx_uint_t i;
 171
 172     /* Gets the array from the config structure using the defined
 173      * offset, and if the pointer is unset it creates a new one.
 174      * (The first element is the directive itself, so we should be
 175      * offset by 1)
 176      */
 177     office_hours = (ngx_array_t **) (conf_structure + cmd->offset);
 178
 179     if (*office_hours == NGX_CONF_UNSET_PTR) {
 180         *office_hours = ngx_array_create(cf->pool, cf->args->nelts - 1,
 181                                          sizeof(ngx_str_t));
 182
 183         if (*office_hours == NULL) {
 184             return NGX_CONF_ERROR;
 185         }
 186     }
 187     value = cf->args->elts;
 188
 189     for (i = 1; i < cf->args->nelts; ++i) {
 190         hours = ngx_array_push(*office_hours);
 191         if (hours == NULL) {
 192             return NGX_CONF_ERROR;
 193         }
 194         *hours = value[i];
 195     }
 196
 197     return NGX_CONF_OK;
 198 }
 199
 200
 201 /*
 202  * Config Creator
 203  * Initializes the configuration structure
 204  */
 205
 206 static void *ngx_http_office_hours_create_conf(ngx_conf_t * cf)
 207 {
 208
 209     ngx_http_office_hours_conf_t *conf;
 210
 211     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_office_hours_conf_t));
 212
 213     if (conf == NULL) {
 214         return NULL;
 215     }
 216     conf->office_hours = NGX_CONF_UNSET_PTR;
 217
 218     return conf;
 219 }
 220
 221 /*
 222  * Merge Config Values
 223  * Sets the defaults for the configuration and merges
 224  * with other configurations
 225  */
 226
 227 static char *ngx_http_office_hours_merge_conf(ngx_conf_t * cf,
 228         void *parent, void *child)
 229 {
 230
 231     ngx_http_office_hours_conf_t *prev = parent;
 232     ngx_http_office_hours_conf_t *conf = child;
 233
 234     ngx_conf_merge_ptr_value(conf->office_hours, prev->office_hours, NULL);
 235
 236     return NGX_CONF_OK;
 237 }
 238
 239 /*
 240  * Parse the office hour strings in the configuration file
 241  * to fill out the hours array (in seconds)
 242  */
 243
 244 static ngx_uint_t ** parse_office_hours(ngx_array_t * office_hours)
 245 {
 246
 247     ngx_str_t *hours;
 248     ngx_uint_t ** parsed_office_hours;
 249     ngx_uint_t i, j;
 250
 251     parsed_office_hours = malloc(7 * sizeof(ngx_uint_t *));
 252
 253     hours = office_hours->elts;
 254
 255     /*
 256      * On the configuration file, the leftmost element
 257      * always applies to all remaining days, all others
 258      * are read from right to left. So first we will apply
 259      * the initial override, and then iterate based on the
 260      * number of overrides
 261      */
 262
 263     for (i = 0; i < WEEK_LENGTH + 1 - office_hours->nelts; ++i) {
 264         parsed_office_hours[i] = parse_office_hours_string(hours[0]);
 265     }
 266
 267     for (i = 1; i < office_hours->nelts; ++i) {
 268         j = WEEK_LENGTH - office_hours->nelts + i;
 269         parsed_office_hours[j] = parse_office_hours_string(hours[i]);
 270     }
 271
 272     return parsed_office_hours;
 273 }
 274
 275 /*
 276  * Given a time string or the closed token, return a tuple
 277  * of numbers representing opening and closing hours
 278  */
 279
 280 static ngx_uint_t * parse_office_hours_string(ngx_str_t office_hours)
 281 {
 282
 283     int captures[(1 + 4) * 3];
 284     ngx_int_t n;
 285     ngx_uint_t * parsed_hours;
 286
 287     parsed_hours = malloc(2 * sizeof(ngx_uint_t));
 288
 289     if(ngx_strcmp(office_hours.data, CLOSED_TOKEN) == 0) {
 290         parsed_hours[0] = 0;
 291         parsed_hours[1] = 0;
 292         return parsed_hours;
 293     }
 294
 295     n = ngx_regex_exec(rc.regex, &office_hours, captures, (1 + 4) * 3);
 296
 297     if (n >= 0) {
 298         /* Opening Hours */
 299
 300         parsed_hours[0] = 60 * 60 * parse_number(office_hours, captures[2], captures[3]);
 301         parsed_hours[0] = parsed_hours[0] + 60 * parse_number(office_hours, captures[4], captures[5]);
 302
 303         parsed_hours[1] = 60 * 60 * parse_number(office_hours, captures[6], captures[7]);
 304         parsed_hours[1] = parsed_hours[1] + 60 * parse_number(office_hours, captures[8], captures[9]);
 305
 306         return parsed_hours;
 307     }
 308
 309     /* Non-matching strings count as open */
 310
 311     parsed_hours[0] = 0;
 312     parsed_hours[1] = 86400;
 313     return parsed_hours;
 314 }
 315
 316 /*
 317  * Given an office hours array, it returns whether or not
 318  * it is currently within office hours.
 319  */
 320
 321 static ngx_flag_t within_office_hours(ngx_uint_t ** office_hours)
 322 {
 323
 324     time_t now;
 325     ngx_uint_t day_of_week, seconds_of_day;
 326     ngx_uint_t * current_hours;
 327
 328     ngx_time_update();
 329     now = ngx_time();
 330     day_of_week = get_day_of_week(now);
 331     seconds_of_day = get_seconds_of_day(now);
 332     current_hours = office_hours[day_of_week];
 333
 334     return seconds_of_day >= current_hours[0] && seconds_of_day <= current_hours[1];
 335 }
 336
 337 /*
 338  * Calculate the day of the week given a timestamp
 339  */
 340 static ngx_uint_t get_day_of_week(time_t time)
 341 {
 342
 343     /* Epoch was thursday, so add 3 so we start on monday */
 344     return (time / 86400 + 3) % 7;
 345 }
 346
 347 /*
 348  * Calculate the number of seconds elapsed today
 349  */
 350 static ngx_uint_t get_seconds_of_day(time_t time)
 351 {
 352
 353     return time - (time / 86400) * 86400;
 354 }
 355
 356 /*
 357  * Parses a string, returns 0 if match was not found
 358  */
 359 static ngx_uint_t parse_number(ngx_str_t string, ngx_uint_t start, ngx_uint_t end)
 360 {
 361
 362     if (end - start == 0) {
 363         return 0;
 364     }
 365
 366     return ngx_atoi(&string.data[start], end - start);
 367 }
 368
 369 /*
 370  * Postconfig Initialization Handler
 371  * Sets the request filter at the top of the chain
 372  */
 373
 374 static ngx_int_t ngx_http_office_hours_init(ngx_conf_t * cf)
 375 {
 376
 377     ngx_http_next_body_filter = ngx_http_top_body_filter;
 378     ngx_http_top_body_filter = ngx_http_office_hours_body_filter;
 379
 380     rc.pattern = TIME_REGEX;
 381     rc.pool = cf->pool;
 382     if (ngx_regex_compile(&rc) != NGX_OK) {
 383         return NGX_ERROR;
 384     }
 385
 386     return NGX_OK;
 387 }