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 #include <ngx_config.h>
  15 #include <ngx_core.h>
  16 #include <ngx_http.h>
  17
  18 /*
  19  * Declarations
  20  */
  21
  22 /* Constants */
  23
  24 const ngx_uint_t WEEK_LENGTH = 7;
  25 const char * CLOSED_TOKEN = "closed";
  26 const ngx_str_t TIME_REGEX = ngx_string("([0-9]{1,2})(?:\\:([0-9]{2}))?\\-([0-9]{1,2})(?:\\:([0-9]{2}))?");
  27 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>");
  28 const ngx_str_t OPEN_SERVER_TIME_HTML = ngx_string("</ul><p><em>Current Server Time is: ");
  29 const ngx_str_t CLOSE_SERVER_TIME_HTML = ngx_string("</em></p>");
  30 const ngx_str_t FOOT_HTML = ngx_string("</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_str_t   additional_information;
  46 } ngx_http_office_hours_conf_t;
  47
  48 /* Lifecycle Functions For Module Context */
  49
  50 static void *ngx_http_office_hours_create_conf(ngx_conf_t * cf);
  51 static char *ngx_http_office_hours_merge_conf(ngx_conf_t * cf,
  52         void *parent, void *child);
  53 static ngx_int_t ngx_http_office_hours_init(ngx_conf_t * cf);
  54
  55 /* Configuration Handler */
  56
  57 static char *ngx_http_office_hours(ngx_conf_t * cf, ngx_command_t * cmd,
  58                                    void *conf);
  59
  60 /* Filter Storage */
  61
  62 static ngx_http_output_header_filter_pt ngx_http_next_header_filter;
  63 static ngx_http_output_body_filter_pt ngx_http_next_body_filter;
  64
  65 /* Utility Functions */
  66 static ngx_uint_t ** parse_office_hours(ngx_array_t * office_hours);
  67 static ngx_uint_t * parse_office_hours_string(ngx_str_t office_hours);
  68 static ngx_flag_t within_office_hours(ngx_uint_t ** office_hours);
  69 static ngx_uint_t get_day_of_week(time_t time);
  70 static ngx_uint_t get_seconds_of_day(time_t time);
  71 static ngx_uint_t parse_number(ngx_str_t string, ngx_uint_t start, ngx_uint_t end);
  72 static ngx_str_t create_output_html(ngx_http_office_hours_conf_t * conf);
  73 static char * format_hours(ngx_uint_t * seconds, char * day);
  74 static char * format_seconds(ngx_uint_t seconds);
  75 static char * left_pad(unsigned int number);
  76
  77 /* Globals */
  78 ngx_regex_compile_t rc;
  79 ngx_str_t OUTPUT_HTML;
  80
  81 /*
  82  * Module Definitions
  83  */
  84
  85 /* Module Directives */
  86
  87 static ngx_command_t ngx_http_office_hours_commands[] = {
  88     {
  89         ngx_string("office_hours"),
  90         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,
  91         ngx_http_office_hours,
  92         NGX_HTTP_LOC_CONF_OFFSET,
  93         offsetof(ngx_http_office_hours_conf_t, office_hours),
  94         NULL
  95     },
  96     {
  97         ngx_string("office_hours_additional_information"),
  98         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,
  99         ngx_conf_set_str_slot,
 100         NGX_HTTP_LOC_CONF_OFFSET,
 101         offsetof(ngx_http_office_hours_conf_t, additional_information),
 102         NULL
 103     },
 104
 105     ngx_null_command
 106 };
 107
 108 /* Module Context */
 109
 110 static ngx_http_module_t ngx_http_office_hours_filter_module_ctx = {
 111     NULL,                       /* Preconfiguration */
 112     ngx_http_office_hours_init, /* Postconfiguration */
 113
 114     NULL,                       /* Create main configuration */
 115     NULL,                       /* Initialize main configuration */
 116
 117     NULL,                       /* Create server configuration */
 118     NULL,                       /* Merge server configuration */
 119
 120     ngx_http_office_hours_create_conf,  /* Create location configuration */
 121     ngx_http_office_hours_merge_conf    /* Merge location configuration */
 122 };
 123
 124 /* Module Definition */
 125
 126 ngx_module_t ngx_http_office_hours_filter_module = {
 127     NGX_MODULE_V1,              //Module Version
 128     &ngx_http_office_hours_filter_module_ctx,   //Module context
 129     ngx_http_office_hours_commands,     //Module commands
 130     NGX_HTTP_MODULE,            //Module Type
 131     NULL,                       //Initialize Master
 132     NULL,                       //Initialize Module
 133     NULL,                       //Initialize Process
 134     NULL,                       //Initialize Thread
 135     NULL,                       //Exit Thread
 136     NULL,                       //Exit Process
 137     NULL,                       //Exit Master
 138     NGX_MODULE_V1_PADDING
 139 };
 140
 141 /*
 142  * Main Header Filter
 143  * If the current time is within office hours, it goes to the next
 144  * handler. Otherwise it sets the headers to 403
 145  */
 146
 147 static ngx_int_t
 148 ngx_http_office_hours_header_filter(ngx_http_request_t * r)
 149 {
 150
 151     ngx_uint_t ** parsed_office_hours;
 152     ngx_http_office_hours_conf_t *conf;
 153
 154     conf =
 155         ngx_http_get_module_loc_conf(r,
 156                                      ngx_http_office_hours_filter_module);
 157
 158     if (conf->office_hours == NULL) {
 159         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 160                       "Office hours disabled");
 161         return ngx_http_next_header_filter(r);
 162     }
 163
 164     parsed_office_hours = parse_office_hours(conf->office_hours);
 165
 166     if (within_office_hours(parsed_office_hours)) {
 167         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 168                       "Within office hours");
 169         return ngx_http_next_header_filter(r);
 170     }
 171
 172     ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 173                   "Outside office hours");
 174
 175     if (OUTPUT_HTML.data == NULL) {
 176         OUTPUT_HTML = create_output_html(conf);
 177     }
 178
 179     r->headers_out.status = NGX_HTTP_FORBIDDEN;
 180     r->headers_out.content_length_n = OUTPUT_HTML.len;
 181
 182     return ngx_http_next_header_filter(r);
 183 }
 184
 185 /*
 186  * Main Body Filter
 187  * If the current time is within office hours, it goes to the next
 188  * handler. Otherwise it replaces the body with the office hours.
 189  */
 190
 191 static ngx_int_t
 192 ngx_http_office_hours_body_filter(ngx_http_request_t * r, ngx_chain_t *in)
 193 {
 194
 195     ngx_buf_t    *b;
 196     ngx_uint_t ** parsed_office_hours;
 197     ngx_chain_t   out;
 198     ngx_http_office_hours_conf_t *conf;
 199
 200     conf =
 201         ngx_http_get_module_loc_conf(r,
 202                                      ngx_http_office_hours_filter_module);
 203
 204     if (conf->office_hours == NULL) {
 205         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 206                       "Office hours disabled");
 207         return ngx_http_next_body_filter(r, in);
 208     }
 209
 210     parsed_office_hours = parse_office_hours(conf->office_hours);
 211
 212     if (within_office_hours(parsed_office_hours)) {
 213         ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 214                       "Within office hours");
 215         return ngx_http_next_body_filter(r, in);
 216     }
 217
 218     ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
 219                   "Outside office hours");
 220
 221     if (OUTPUT_HTML.data == NULL) {
 222         OUTPUT_HTML = create_output_html(conf);
 223     }
 224
 225     b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
 226     if (b == NULL) {
 227         ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "Failed to allocate response buffer.");
 228         return NGX_HTTP_INTERNAL_SERVER_ERROR;
 229     }
 230
 231     out.buf = b;
 232     out.next = NULL;
 233
 234     b->start = OUTPUT_HTML.data;
 235     b->pos = b->start;
 236     b->end = OUTPUT_HTML.data + OUTPUT_HTML.len;
 237     b->last = b->end;
 238
 239     b->memory = 1;
 240     b->last_buf = 1;
 241
 242     return ngx_http_next_body_filter(r, &out);
 243 }
 244
 245 /*
 246  * Callback for `office_hours ` directive
 247  * Reads the configuration loaded from the config file(cf)
 248  * And writes it to the right place in the module configuration(conf)
 249  */
 250
 251 static char *ngx_http_office_hours(ngx_conf_t * cf, ngx_command_t * cmd,
 252                                    void *conf)
 253 {
 254
 255     char *conf_structure = conf;
 256
 257     ngx_str_t *hours, *value;
 258     ngx_array_t **office_hours;
 259     ngx_uint_t i;
 260
 261     /* Gets the array from the config structure using the defined
 262      * offset, and if the pointer is unset it creates a new one.
 263      * (The first element is the directive itself, so we should be
 264      * offset by 1)
 265      */
 266     office_hours = (ngx_array_t **) (conf_structure + cmd->offset);
 267
 268     if (*office_hours == NGX_CONF_UNSET_PTR) {
 269         *office_hours = ngx_array_create(cf->pool, cf->args->nelts - 1,
 270                                          sizeof(ngx_str_t));
 271
 272         if (*office_hours == NULL) {
 273             return NGX_CONF_ERROR;
 274         }
 275     }
 276     value = cf->args->elts;
 277
 278     for (i = 1; i < cf->args->nelts; ++i) {
 279         hours = ngx_array_push(*office_hours);
 280         if (hours == NULL) {
 281             return NGX_CONF_ERROR;
 282         }
 283         *hours = value[i];
 284     }
 285
 286     return NGX_CONF_OK;
 287 }
 288
 289 /*
 290  * Config Creator
 291  * Initializes the configuration structure
 292  */
 293
 294 static void *ngx_http_office_hours_create_conf(ngx_conf_t * cf)
 295 {
 296
 297     ngx_http_office_hours_conf_t *conf;
 298
 299     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_office_hours_conf_t));
 300
 301     if (conf == NULL) {
 302         return NULL;
 303     }
 304     conf->office_hours = NGX_CONF_UNSET_PTR;
 305
 306     return conf;
 307 }
 308
 309 /*
 310  * Merge Config Values
 311  * Sets the defaults for the configuration and merges
 312  * with other configurations
 313  */
 314
 315 static char *ngx_http_office_hours_merge_conf(ngx_conf_t * cf,
 316         void *parent, void *child)
 317 {
 318
 319     ngx_http_office_hours_conf_t *prev = parent;
 320     ngx_http_office_hours_conf_t *conf = child;
 321
 322     ngx_conf_merge_ptr_value(conf->office_hours, prev->office_hours, NULL);
 323
 324     return NGX_CONF_OK;
 325 }
 326
 327 /*
 328  * Parse the office hour strings in the configuration file
 329  * to fill out the hours array (in seconds)
 330  */
 331
 332 static ngx_uint_t ** parse_office_hours(ngx_array_t * office_hours)
 333 {
 334
 335     ngx_str_t *hours;
 336     ngx_uint_t ** parsed_office_hours;
 337     ngx_uint_t i, j;
 338
 339     parsed_office_hours = malloc(7 * sizeof(ngx_uint_t *));
 340
 341     hours = office_hours->elts;
 342
 343     /*
 344      * On the configuration file, the leftmost element
 345      * always applies to all remaining days, all others
 346      * are read from right to left. So first we will apply
 347      * the initial override, and then iterate based on the
 348      * number of overrides
 349      */
 350
 351     for (i = 0; i < WEEK_LENGTH + 1 - office_hours->nelts; ++i) {
 352         parsed_office_hours[i] = parse_office_hours_string(hours[0]);
 353     }
 354
 355     for (i = 1; i < office_hours->nelts; ++i) {
 356         j = WEEK_LENGTH - office_hours->nelts + i;
 357         parsed_office_hours[j] = parse_office_hours_string(hours[i]);
 358     }
 359
 360     return parsed_office_hours;
 361 }
 362
 363 /*
 364  * Given a time string or the closed token, return a tuple
 365  * of numbers representing opening and closing hours
 366  */
 367
 368 static ngx_uint_t * parse_office_hours_string(ngx_str_t office_hours)
 369 {
 370
 371     int captures[(1 + 4) * 3];
 372     ngx_int_t n;
 373     ngx_uint_t * parsed_hours;
 374
 375     parsed_hours = malloc(2 * sizeof(ngx_uint_t));
 376
 377     if(ngx_strcmp(office_hours.data, CLOSED_TOKEN) == 0) {
 378         parsed_hours[0] = 0;
 379         parsed_hours[1] = 0;
 380         return parsed_hours;
 381     }
 382
 383     n = ngx_regex_exec(rc.regex, &office_hours, captures, (1 + 4) * 3);
 384
 385     if (n >= 0) {
 386         /* Opening Hours */
 387
 388         parsed_hours[0] = 60 * 60 * parse_number(office_hours, captures[2], captures[3]);
 389         parsed_hours[0] = parsed_hours[0] + 60 * parse_number(office_hours, captures[4], captures[5]);
 390
 391         parsed_hours[1] = 60 * 60 * parse_number(office_hours, captures[6], captures[7]);
 392         parsed_hours[1] = parsed_hours[1] + 60 * parse_number(office_hours, captures[8], captures[9]);
 393
 394         return parsed_hours;
 395     }
 396
 397     /* Non-matching strings count as open */
 398
 399     parsed_hours[0] = 0;
 400     parsed_hours[1] = 86400;
 401     return parsed_hours;
 402 }
 403
 404 /*
 405  * Given an office hours array, it returns whether or not
 406  * it is currently within office hours.
 407  */
 408
 409 static ngx_flag_t within_office_hours(ngx_uint_t ** office_hours)
 410 {
 411
 412     time_t now;
 413     ngx_uint_t day_of_week, seconds_of_day;
 414     ngx_uint_t * current_hours;
 415
 416     ngx_time_update();
 417     now = ngx_time();
 418     day_of_week = get_day_of_week(now);
 419     seconds_of_day = get_seconds_of_day(now);
 420     current_hours = office_hours[day_of_week];
 421
 422     return seconds_of_day >= current_hours[0] && seconds_of_day <= current_hours[1];
 423 }
 424
 425 /*
 426  * Calculate the day of the week given a timestamp
 427  */
 428
 429 static ngx_uint_t get_day_of_week(time_t time)
 430 {
 431
 432     /* Epoch was thursday, so add 3 so we start on monday */
 433     return (time / 86400 + 3) % 7;
 434 }
 435
 436 /*
 437  * Calculate the number of seconds elapsed today
 438  */
 439
 440 static ngx_uint_t get_seconds_of_day(time_t time)
 441 {
 442
 443     return time - (time / 86400) * 86400;
 444 }
 445
 446 /*
 447  * Parses a string, returns 0 if match was not found
 448  */
 449
 450 static ngx_uint_t parse_number(ngx_str_t string, ngx_uint_t start, ngx_uint_t end)
 451 {
 452
 453     if (end - start == 0) {
 454         return 0;
 455     }
 456
 457     return ngx_atoi(&string.data[start], end - start);
 458 }
 459
 460 /*
 461  * Given the current office hours configuration it creates the custom
 462  * HTML
 463  */
 464
 465 static ngx_str_t create_output_html(ngx_http_office_hours_conf_t * conf)
 466 {
 467
 468     char * output_buffer;
 469     time_t now;
 470     ngx_str_t output_html;
 471     ngx_uint_t i, seconds_of_day;
 472     ngx_uint_t ** parsed_office_hours;
 473
 474     size_t base_size = 1024;
 475     size_t additional_info_size = conf->additional_information.len;
 476     size_t buffer_size = base_size + additional_info_size + 1;
 477     output_buffer = malloc(buffer_size * sizeof(char));
 478
 479     /* UH-OH we couldn't allocate the bufer */
 480     if (!output_buffer) {
 481         output_html.data = NULL;
 482         output_html.len = 0;
 483         return output_html;
 484     }
 485
 486     parsed_office_hours = parse_office_hours(conf->office_hours);
 487     now = ngx_time();
 488     seconds_of_day = get_seconds_of_day(now);
 489
 490     int written = 0;
 491
 492     written += snprintf(output_buffer + written, buffer_size - written, "%s", (char *) HEAD_HTML.data);
 493
 494     for (i = 0; i < 7; ++i) {
 495         written +=  snprintf(output_buffer + written, buffer_size - written, "%s", format_hours(parsed_office_hours[i], (char *) DAY_NAMES[i]));
 496     }
 497
 498     written += snprintf(output_buffer + written, buffer_size - written, "%s", (char *) OPEN_SERVER_TIME_HTML.data);
 499     written += snprintf(output_buffer + written, buffer_size - written, "%s", format_seconds(seconds_of_day));
 500     written += snprintf(output_buffer + written, buffer_size - written, "%s", (char *) CLOSE_SERVER_TIME_HTML.data);
 501
 502     if (conf->additional_information.len > 0) {
 503         char additional_info[conf->additional_information.len + 1];
 504         ngx_memcpy(additional_info, conf->additional_information.data, conf->additional_information.len);
 505         additional_info[conf->additional_information.len] = '\0';
 506         written += snprintf(output_buffer + written, buffer_size - written, "%s", additional_info);
 507     }
 508
 509     snprintf(output_buffer + written, buffer_size - written, "%s", (char *) FOOT_HTML.data);
 510
 511     output_html.data = (unsigned char *) output_buffer;
 512     output_html.len = strlen(output_buffer);
 513
 514     return output_html;
 515 }
 516
 517 /*
 518  * Given a tuple of seconds and a day name, outputs an HTML
 519  * string containing the formatted data as a list item
 520  */
 521
 522 static char * format_hours(ngx_uint_t * hours, char * day)
 523 {
 524
 525     char * output_html;
 526
 527     output_html = malloc(64 * sizeof(char));
 528     if (hours[0] == hours[1]) {
 529         sprintf(output_html, "<li><strong>%s</strong>: CLOSED</li>",
 530                 day
 531                );
 532         return output_html;
 533     }
 534
 535     sprintf(output_html, "<li><strong>%s</strong>: %s - %s</li>",
 536             day,
 537             (char *) format_seconds(hours[0]),
 538             (char *) format_seconds(hours[1])
 539            );
 540
 541     return output_html;
 542 }
 543
 544 /*
 545  * Given seconds of the day, it returns a string showing
 546  * HH:MM in 24 hour format
 547  */
 548
 549 static char * format_seconds(ngx_uint_t seconds)
 550 {
 551
 552     char * output_html;
 553     unsigned int hours, minutes;
 554
 555     output_html = malloc(6 * sizeof(char));
 556
 557     hours = seconds / 60 / 60;
 558     minutes = (seconds / 60) % 60;
 559
 560     sprintf(output_html, "%s:%s",
 561             left_pad(hours),
 562             left_pad(minutes)
 563            );
 564
 565     return output_html;
 566 }
 567
 568 /*
 569  * Returns a number as a string adding 0 if < 10
 570  */
 571
 572 static char * left_pad(unsigned int number)
 573 {
 574
 575     char * output_string;
 576     char * padding;
 577
 578     padding = "";
 579     output_string = malloc(4 * sizeof(char));
 580
 581     if (number < 10) {
 582         padding = "0";
 583     }
 584
 585     snprintf(output_string, 4, "%s%u", padding, number);
 586
 587     return output_string;
 588 }
 589
 590 /*
 591  * Postconfig Initialization Handler
 592  * Sets the request filter at the top of the chain
 593  */
 594
 595 static ngx_int_t ngx_http_office_hours_init(ngx_conf_t * cf)
 596 {
 597
 598     ngx_http_next_header_filter = ngx_http_top_header_filter;
 599     ngx_http_top_header_filter = ngx_http_office_hours_header_filter;
 600
 601     ngx_http_next_body_filter = ngx_http_top_body_filter;
 602     ngx_http_top_body_filter = ngx_http_office_hours_body_filter;
 603
 604     rc.pattern = TIME_REGEX;
 605     rc.pool = cf->pool;
 606     if (ngx_regex_compile(&rc) != NGX_OK) {
 607         return NGX_ERROR;
 608     }
 609
 610     return NGX_OK;
 611 }