/**
 * mod_range_limit
 * ---------------
 * Limit the number of range-requests per connection
 * 
 * Configuration:
 *   RangeLimit {On|Off}	Enable/Disable usage of module, works per vhost
 *   RangeCount {int}		Set the maximum number of range-requests, works per vhost
 * 
 * 
 * Author: Bernd Holzmueller <bernd@tiggerswelt.net>
 * Contributions by: Jan Philipp Guenther <jan.guenther@tiggerswelt.net>
 * 
 * License: Creative Commons Attribution-Share Alike 3.0 Germany
 *          http://creativecommons.org/licenses/by-sa/3.0/de/
 * 
 * Copyright (C) tiggersWelt.net, 2011
 **/

#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"
#include "http_vhost.h"
#include "apr_strings.h"

module AP_MODULE_DECLARE_DATA range_limit_module;

typedef struct {
    int enable;
    int count;
} range_limit_server_cfg;


void *range_limit_create_dir_cfg (apr_pool_t *p, char *dummy) {
  range_limit_server_cfg *cfg = (range_limit_server_cfg *)apr_pcalloc (p, sizeof(range_limit_server_cfg));
  
  if (!cfg)
    return NULL;
  
  cfg->enable = 0;
  cfg->count = 0;
  
  return (void *)cfg;
}


static const char *range_limit_enable (cmd_parms *cmd, void *config, int flag) {
  server_rec *s = cmd->server;
  range_limit_server_cfg *cfg = (range_limit_server_cfg *)config;
  
  if (!cfg)
    return NULL;
  
  cfg->enable = flag;
  
  return NULL;
}

static const char *range_limit_counter (cmd_parms *cmd, void *config, const char *arg) {
  server_rec *s = cmd->server;
  range_limit_server_cfg *cfg = (range_limit_server_cfg *)config;
  
  if (!cfg)
    return NULL;
  
  cfg->count = atol (arg);
  
  return NULL;
}

static int range_limit (request_rec *r) {
  range_limit_server_cfg *cfg = (range_limit_server_cfg *)ap_get_module_config (r->per_dir_config, &range_limit_module);
  const char *range;
  int counter = 0;
  
  if (!cfg)
    return DECLINED;
  
  if (!cfg->enable || !cfg->count)
    return DECLINED;
  
  if (!(range = apr_table_get(r->headers_in, "Range")))
    if (!(range = apr_table_get(r->headers_in, "Request-Range")))
      return DECLINED;
  
  for (; *range; range++)
    if ((*range == ',') && (++counter > cfg->count))
      return HTTP_RANGE_NOT_SATISFIABLE;
  
  return DECLINED;
}

static const command_rec range_limit_cmds[] = {
  AP_INIT_FLAG (
    "RangeLimit",
    range_limit_enable,
    NULL,
    RSRC_CONF,
    "Enable Limits for Range-Headers"
  ),
  AP_INIT_TAKE1 (
    "RangeCount",
    range_limit_counter,
    NULL,
    RSRC_CONF,
    "Set the maximum number of range chunks per request"
  ),
  { NULL }
};

static void register_hooks(apr_pool_t *p) {
    ap_hook_post_read_request (range_limit, NULL, NULL, APR_HOOK_FIRST);
}

module AP_MODULE_DECLARE_DATA range_limit_module = {
    STANDARD20_MODULE_STUFF,
    range_limit_create_dir_cfg,
    NULL,
    NULL,
    NULL,
    range_limit_cmds,
    register_hooks,
};