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 const ngx_str_t HEAD_HTML = ngx_string("<!doctype html><html><head><title>This website is currently closed!</title></head><body><h1>This website is currently closed!</h1><p>This website has closed for the day, please check our office hours below</p><ul>");
  29 const ngx_str_t MIDDLE_HTML = ngx_string("</ul><p><em>Current Server Time is: ");
  30 const ngx_str_t FOOT_HTML = ngx_string("</em></p></body></html>");
  31 const char * DAY_NAMES[7] = {
  32     "Monday",
  33     "Tuesday",
  34     "Wednesday",
  35     "Thursday",
  36     "Friday",
  37     "Saturday",
  38     "Sunday"
  39 };
  40
  41 /* Main Configuration Structure */
  42
  43 typedef struct {
  44     ngx_array_t *office_hours;
  45 } ngx_http_office_hours_conf_t;
  46
  47 /* Lifecycle Functions For Module Context */
  48
  49 static void *ngx_http_office_hours_create_conf(ngx_conf_t * cf);
  50 static char *ngx_http_office_hours_merge_conf(ngx_conf_t * cf,
  51         void *parent, void *child);
  52 static ngx_int_t ngx_http_office_hours_init(ngx_conf_t * cf);
  53
  54 /* Configuration Handler */
  55
  56 static char *ngx_http_office_hours(ngx_conf_t * cf, ngx_command_t * cmd,
  57                                    void *conf);
  58
  59 /* Filter Storage */
  60
  61 static ngx_http_output_header_filter_pt ngx_http_next_header_filter;
  62 static ngx_http_output_body_filter_pt ngx_http_next_body_filter;
  63
  64 /* Utility Functions */
  65 static ngx_uint_t ** parse_office_hours(ngx_array_t * office_hours);
  66 static ngx_uint_t * parse_office_hours_string(ngx_str_t office_hours);
  67 static ngx_flag_t within_office_hours(ngx_uint_t ** office_hours);
  68 static ngx_uint_t get_day_of_week(time_t time);
  69 static ngx_uint_t get_seconds_of_day(time_t time);
  70 static ngx_uint_t parse_number(ngx_str_t string, ngx_uint_t start, ngx_uint_t end);
  71 static ngx_str_t create_output_html(ngx_http_office_hours_conf_t * conf);
  72 static char * format_hours(ngx_uint_t * seconds, char * day);
  73 static char * format_seconds(ngx_uint_t seconds);
  74 static char * left_pad(unsigned int number);
  75
  76 /* Globals */
  77 ngx_regex_compile_t rc;
  78 ngx_str_t OUTPUT_HTML;
  79
  80 /*
  81  * Module Definitions
  82  */
  83
  84 /* Module Directives */
  85
  86 static ngx_command_t ngx_http_office_hours_commands[] = {
  87     {
  88         ngx_string("office_hours"),
  89         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,
  90         ngx_http_office_hours,
  91         NGX_HTTP_LOC_CONF_OFFSET,
  92         offsetof(ngx_http_office_hours_conf_t, office_hours),
  93         NULL
  94     },
  95
  96     ngx_null_command
  97 };
  98
  99
 100 /* Module Context */
 101
 102 static ngx_http_module_t ngx_http_office_hours_filter_module_ctx = {
 103     NULL,                       /* Preconfiguration */
 104     ngx_http_office_hours_init, /* Postconfiguration */
 105
 106     NULL,                       /* Create main configuration */
 107     NULL,                       /* Initialize main configuration */
 108
 109     NULL,                       /* Create server configuration */
 110     NULL,                       /* Merge server configuration */
 111
 112     ngx_http_office_hours_create_conf,  /* Create location configuration */
 113     ngx_http_office_hours_merge_conf    /* Merge location configuration */
 114 };
 115
 116
 117 /* Module Definition */
 118
 119 ngx_module_t ngx_http_office_hours_filter_module = {
 120     NGX_MODULE_V1,              //Module Version
 121     &ngx_http_office_hours_filter_module_ctx,   //Module context
 122     ngx_http_office_hours_commands,     //Module commands
 123     NGX_HTTP_MODULE,            //Module Type
 124     NULL,                       //Initialize Master
 125     NULL,                       //Initialize Module
 126     NULL,                       //Initialize Process
 127     NULL,                       //Initialize Thread
 128     NULL,                       //Exit Thread
 129     NULL,                       //Exit Process
 130     NULL,                       //Exit Master
 131     NGX_MODULE_V1_PADDING
 132 };
 133
 134
 135 /*
 136  * Main Header Filter
 137  * If the current time is within office hours, it goes to the next
 138  * handler. Otherwise it sets the headers to 403
 139  */
 140
 141 static ngx_int_t
 142 ngx_http_office_hours_header_filter(ngx_http_request_t * r)
 143 {
 144
 145     ngx_uint_t ** parsed_office_hours;
 146     ngx_http_office_hours_conf_t *conf;
 147
 148     conf =
 149         ngx_http_get_module_loc_conf(r,
 150                                      ngx_http_office_hours_filter_module);
 151
 152
 153     if (conf->office_hours == NULL) {
 154         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 155                       "Office hours disabled");
 156         return ngx_http_next_header_filter(r);
 157     }
 158
 159     parsed_office_hours = parse_office_hours(conf->office_hours);
 160
 161     if (within_office_hours(parsed_office_hours)) {
 162         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 163                       "Within office hours");
 164         return ngx_http_next_header_filter(r);
 165     }
 166
 167     ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 168                   "Outside office hours");
 169
 170     if (OUTPUT_HTML.data == NULL) {
 171         OUTPUT_HTML = create_output_html(conf);
 172     }
 173
 174     r->headers_out.status = NGX_HTTP_FORBIDDEN;
 175     r->headers_out.content_length_n = OUTPUT_HTML.len;
 176
 177     return ngx_http_next_header_filter(r);
 178 }
 179
 180 /*
 181  * Main Body Filter
 182  * If the current time is within office hours, it goes to the next
 183  * handler. Otherwise it replaces the body with the office hours.
 184  */
 185
 186 static ngx_int_t
 187 ngx_http_office_hours_body_filter(ngx_http_request_t * r, ngx_chain_t *in)
 188 {
 189
 190     ngx_buf_t    *b;
 191     ngx_uint_t ** parsed_office_hours;
 192     ngx_chain_t   out;
 193     ngx_http_office_hours_conf_t *conf;
 194
 195     conf =
 196         ngx_http_get_module_loc_conf(r,
 197                                      ngx_http_office_hours_filter_module);
 198
 199
 200     if (conf->office_hours == NULL) {
 201         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 202                       "Office hours disabled");
 203         return ngx_http_next_body_filter(r, in);
 204     }
 205
 206     parsed_office_hours = parse_office_hours(conf->office_hours);
 207
 208     if (within_office_hours(parsed_office_hours)) {
 209         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 210                       "Within office hours");
 211         return ngx_http_next_body_filter(r, in);
 212     }
 213
 214     ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 215                   "Outside office hours");
 216
 217     if (OUTPUT_HTML.data == NULL) {
 218         OUTPUT_HTML = create_output_html(conf);
 219     }
 220
 221     b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
 222     if (b == NULL) {
 223         ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "Failed to allocate response buffer.");
 224         return NGX_HTTP_INTERNAL_SERVER_ERROR;
 225     }
 226
 227     out.buf = b;
 228     out.next = NULL;
 229
 230     b->start = OUTPUT_HTML.data;
 231     b->pos = b->start;
 232     b->end = OUTPUT_HTML.data + OUTPUT_HTML.len;
 233     b->last = b->end;
 234
 235     b->memory = 1;
 236     b->last_buf = 1;
 237
 238     return ngx_http_next_body_filter(r, &out);
 239 }
 240
 241 /*
 242  * Callback for `office_hours ` directive
 243  * Reads the configuration loaded from the config file(cf)
 244  * And writes it to the right place in the module configuration(conf)
 245  */
 246
 247 static char *ngx_http_office_hours(ngx_conf_t * cf, ngx_command_t * cmd,
 248                                    void *conf)
 249 {
 250
 251     char *conf_structure = conf;
 252
 253     ngx_str_t *hours, *value;
 254     ngx_array_t **office_hours;
 255     ngx_uint_t i;
 256
 257     /* Gets the array from the config structure using the defined
 258      * offset, and if the pointer is unset it creates a new one.
 259      * (The first element is the directive itself, so we should be
 260      * offset by 1)
 261      */
 262     office_hours = (ngx_array_t **) (conf_structure + cmd->offset);
 263
 264     if (*office_hours == NGX_CONF_UNSET_PTR) {
 265         *office_hours = ngx_array_create(cf->pool, cf->args->nelts - 1,
 266                                          sizeof(ngx_str_t));
 267
 268         if (*office_hours == NULL) {
 269             return NGX_CONF_ERROR;
 270         }
 271     }
 272     value = cf->args->elts;
 273
 274     for (i = 1; i < cf->args->nelts; ++i) {
 275         hours = ngx_array_push(*office_hours);
 276         if (hours == NULL) {
 277             return NGX_CONF_ERROR;
 278         }
 279         *hours = value[i];
 280     }
 281
 282     return NGX_CONF_OK;
 283 }
 284
 285
 286 /*
 287  * Config Creator
 288  * Initializes the configuration structure
 289  */
 290
 291 static void *ngx_http_office_hours_create_conf(ngx_conf_t * cf)
 292 {
 293
 294     ngx_http_office_hours_conf_t *conf;
 295
 296     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_office_hours_conf_t));
 297
 298     if (conf == NULL) {
 299         return NULL;
 300     }
 301     conf->office_hours = NGX_CONF_UNSET_PTR;
 302
 303     return conf;
 304 }
 305
 306 /*
 307  * Merge Config Values
 308  * Sets the defaults for the configuration and merges
 309  * with other configurations
 310  */
 311
 312 static char *ngx_http_office_hours_merge_conf(ngx_conf_t * cf,
 313         void *parent, void *child)
 314 {
 315
 316     ngx_http_office_hours_conf_t *prev = parent;
 317     ngx_http_office_hours_conf_t *conf = child;
 318
 319     ngx_conf_merge_ptr_value(conf->office_hours, prev->office_hours, NULL);
 320
 321     return NGX_CONF_OK;
 322 }
 323
 324 /*
 325  * Parse the office hour strings in the configuration file
 326  * to fill out the hours array (in seconds)
 327  */
 328
 329 static ngx_uint_t ** parse_office_hours(ngx_array_t * office_hours)
 330 {
 331
 332     ngx_str_t *hours;
 333     ngx_uint_t ** parsed_office_hours;
 334     ngx_uint_t i, j;
 335
 336     parsed_office_hours = malloc(7 * sizeof(ngx_uint_t *));
 337
 338     hours = office_hours->elts;
 339
 340     /*
 341      * On the configuration file, the leftmost element
 342      * always applies to all remaining days, all others
 343      * are read from right to left. So first we will apply
 344      * the initial override, and then iterate based on the
 345      * number of overrides
 346      */
 347
 348     for (i = 0; i < WEEK_LENGTH + 1 - office_hours->nelts; ++i) {
 349         parsed_office_hours[i] = parse_office_hours_string(hours[0]);
 350     }
 351
 352     for (i = 1; i < office_hours->nelts; ++i) {
 353         j = WEEK_LENGTH - office_hours->nelts + i;
 354         parsed_office_hours[j] = parse_office_hours_string(hours[i]);
 355     }
 356
 357     return parsed_office_hours;
 358 }
 359
 360 /*
 361  * Given a time string or the closed token, return a tuple
 362  * of numbers representing opening and closing hours
 363  */
 364
 365 static ngx_uint_t * parse_office_hours_string(ngx_str_t office_hours)
 366 {
 367
 368     int captures[(1 + 4) * 3];
 369     ngx_int_t n;
 370     ngx_uint_t * parsed_hours;
 371
 372     parsed_hours = malloc(2 * sizeof(ngx_uint_t));
 373
 374     if(ngx_strcmp(office_hours.data, CLOSED_TOKEN) == 0) {
 375         parsed_hours[0] = 0;
 376         parsed_hours[1] = 0;
 377         return parsed_hours;
 378     }
 379
 380     n = ngx_regex_exec(rc.regex, &office_hours, captures, (1 + 4) * 3);
 381
 382     if (n >= 0) {
 383         /* Opening Hours */
 384
 385         parsed_hours[0] = 60 * 60 * parse_number(office_hours, captures[2], captures[3]);
 386         parsed_hours[0] = parsed_hours[0] + 60 * parse_number(office_hours, captures[4], captures[5]);
 387
 388         parsed_hours[1] = 60 * 60 * parse_number(office_hours, captures[6], captures[7]);
 389         parsed_hours[1] = parsed_hours[1] + 60 * parse_number(office_hours, captures[8], captures[9]);
 390
 391         return parsed_hours;
 392     }
 393
 394     /* Non-matching strings count as open */
 395
 396     parsed_hours[0] = 0;
 397     parsed_hours[1] = 86400;
 398     return parsed_hours;
 399 }
 400
 401 /*
 402  * Given an office hours array, it returns whether or not
 403  * it is currently within office hours.
 404  */
 405
 406 static ngx_flag_t within_office_hours(ngx_uint_t ** office_hours)
 407 {
 408
 409     time_t now;
 410     ngx_uint_t day_of_week, seconds_of_day;
 411     ngx_uint_t * current_hours;
 412
 413     ngx_time_update();
 414     now = ngx_time();
 415     day_of_week = get_day_of_week(now);
 416     seconds_of_day = get_seconds_of_day(now);
 417     current_hours = office_hours[day_of_week];
 418
 419     return seconds_of_day >= current_hours[0] && seconds_of_day <= current_hours[1];
 420 }
 421
 422 /*
 423  * Calculate the day of the week given a timestamp
 424  */
 425
 426 static ngx_uint_t get_day_of_week(time_t time)
 427 {
 428
 429     /* Epoch was thursday, so add 3 so we start on monday */
 430     return (time / 86400 + 3) % 7;
 431 }
 432
 433 /*
 434  * Calculate the number of seconds elapsed today
 435  */
 436
 437 static ngx_uint_t get_seconds_of_day(time_t time)
 438 {
 439
 440     return time - (time / 86400) * 86400;
 441 }
 442
 443 /*
 444  * Parses a string, returns 0 if match was not found
 445  */
 446
 447 static ngx_uint_t parse_number(ngx_str_t string, ngx_uint_t start, ngx_uint_t end)
 448 {
 449
 450     if (end - start == 0) {
 451         return 0;
 452     }
 453
 454     return ngx_atoi(&string.data[start], end - start);
 455 }
 456
 457 /*
 458  * Given the current office hours configuration it creates the custom
 459  * HTML
 460  */
 461
 462 static ngx_str_t create_output_html(ngx_http_office_hours_conf_t * conf)
 463 {
 464
 465     char * output_buffer;
 466     time_t now;
 467     ngx_str_t output_html;
 468     ngx_uint_t i, seconds_of_day;
 469     ngx_uint_t ** parsed_office_hours;
 470
 471
 472     output_buffer = malloc(1024 * sizeof(char));
 473     parsed_office_hours = parse_office_hours(conf->office_hours);
 474     now = ngx_time();
 475     seconds_of_day = get_seconds_of_day(now);
 476
 477     sprintf(output_buffer, "%s", (char *) HEAD_HTML.data);
 478
 479     for (i = 0; i < 7; ++i) {
 480         sprintf(output_buffer + strlen(output_buffer), "%s", format_hours(parsed_office_hours[i], (char *) DAY_NAMES[i]));
 481     }
 482
 483     sprintf(output_buffer + strlen(output_buffer), "%s", (char *) MIDDLE_HTML.data);
 484     sprintf(output_buffer + strlen(output_buffer), "%s", format_seconds(seconds_of_day));
 485     sprintf(output_buffer + strlen(output_buffer), "%s", (char *) FOOT_HTML.data);
 486
 487     output_html.data = (unsigned char *) output_buffer;
 488     output_html.len = strlen(output_buffer);
 489
 490     return output_html;
 491 }
 492
 493 /*
 494  * Given a tuple of seconds and a day name, outputs an HTML
 495  * string containing the formatted data as a list item
 496  */
 497
 498 static char * format_hours(ngx_uint_t * hours, char * day)
 499 {
 500
 501     char * output_html;
 502
 503     output_html = malloc(64 * sizeof(char));
 504     if (hours[0] == hours[1]) {
 505         sprintf(output_html, "<li><strong>%s</strong>: CLOSED</li>",
 506                 day
 507                );
 508         return output_html;
 509     }
 510
 511     sprintf(output_html, "<li><strong>%s</strong>: %s - %s</li>",
 512             day,
 513             (char *) format_seconds(hours[0]),
 514             (char *) format_seconds(hours[1])
 515            );
 516
 517     return output_html;
 518 }
 519
 520 /*
 521  * Given seconds of the day, it returns a string showing
 522  * HH:MM in 24 hour format
 523  */
 524
 525 static char * format_seconds(ngx_uint_t seconds)
 526 {
 527
 528     char * output_html;
 529     unsigned int hours, minutes;
 530
 531     output_html = malloc(6 * sizeof(char));
 532
 533     hours = seconds / 60 / 60;
 534     minutes = (seconds / 60) % 60;
 535
 536     sprintf(output_html, "%s:%s",
 537             left_pad(hours),
 538             left_pad(minutes)
 539            );
 540
 541     return output_html;
 542 }
 543
 544 /*
 545  * Returns a number as a string adding 0 if < 10
 546  */
 547
 548 static char * left_pad(unsigned int number)
 549 {
 550
 551     char * output_string;
 552     char * padding;
 553
 554     padding = "";
 555     output_string = malloc(3 * sizeof(char));
 556
 557     if (number < 10) {
 558         padding = "0";
 559     }
 560
 561     sprintf(output_string, "%s%u", padding, number);
 562
 563     return output_string;
 564 }
 565
 566 /*
 567  * Postconfig Initialization Handler
 568  * Sets the request filter at the top of the chain
 569  */
 570
 571 static ngx_int_t ngx_http_office_hours_init(ngx_conf_t * cf)
 572 {
 573
 574     ngx_http_next_header_filter = ngx_http_top_header_filter;
 575     ngx_http_top_header_filter = ngx_http_office_hours_header_filter;
 576
 577     ngx_http_next_body_filter = ngx_http_top_body_filter;
 578     ngx_http_top_body_filter = ngx_http_office_hours_body_filter;
 579
 580     rc.pattern = TIME_REGEX;
 581     rc.pool = cf->pool;
 582     if (ngx_regex_compile(&rc) != NGX_OK) {
 583         return NGX_ERROR;
 584     }
 585
 586     return NGX_OK;
 587 }