text: /**
   * @file netmask.c
   * @author Ambroz Bizjak <ambrop7@gmail.com>
   * 
   * @section LICENSE
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the author nor the
   *    names of its contributors may be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   * 
   * @section DESCRIPTION
   * 
   * Synopsis:
   *   ipv4_prefix_to_mask(string prefix)
   * 
   * Variables:
   *   string (empty) - prefix, converted to dotted decimal format without leading
   *                    zeros
   * 
   * Synopsis:
   *   ipv4_mask_to_prefix(string mask)
   * 
   * Variables:
   *   string (empty) - mask, converted to prefix length
   * 
   * Synopsis:
   *   ipv4_net_from_addr_and_prefix(string addr, string prefix)
   * 
   * Variables:
   *   string (empty) - network part of the address, according to given prefix
   *                    length, in dotted decimal format without leading zeros
   */
  
  #include <stdlib.h>
  #include <string.h>
  #include <stdio.h>
  #include <inttypes.h>
  
  #include <misc/ipaddr.h>
  #include <misc/parse_number.h>
  
  #include <ncd/module_common.h>
  
  #include <generated/blog_channel_ncd_netmask.h>
  
  struct addr_instance {
      NCDModuleInst *i;
      uint32_t addr;
  };
  
  struct prefix_instance {
      NCDModuleInst *i;
      int prefix;
  };
  
  static void addr_func_init_templ (void *vo, NCDModuleInst *i, uint32_t addr)
  {
      struct addr_instance *o = vo;
      o->i = i;
      
      // remember address
      o->addr = addr;
      
      // signal up
      NCDModuleInst_Backend_Up(i);
  }
  
  static void prefix_to_mask_func_init (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
  {
      // read arguments
      NCDValRef prefix_arg;
      if (!NCDVal_ListRead(params->args, 1, &prefix_arg)) {
          ModuleLog(i, BLOG_ERROR, "wrong arity");
          goto fail0;
      }
      if (!NCDVal_IsString(prefix_arg)) {
          ModuleLog(i, BLOG_ERROR, "wrong type");
          goto fail0;
      }
      
      // parse prefix
      int prefix;
      if (!ipaddr_parse_ipv4_prefix(NCDVal_StringMemRef(prefix_arg), &prefix)) {
          ModuleLog(i, BLOG_ERROR, "bad prefix");
          goto fail0;
      }
      
      // make mask
      uint32_t mask = ipaddr_ipv4_mask_from_prefix(prefix);
      
      addr_func_init_templ(vo, i, mask);
      return;
      
  fail0:
      NCDModuleInst_Backend_DeadError(i);
  }
  
  static void ipv4_net_from_addr_and_prefix_func_init (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
  {
      // read arguments
      NCDValRef addr_arg;
      NCDValRef prefix_arg;
      if (!NCDVal_ListRead(params->args, 2, &addr_arg, &prefix_arg)) {
          ModuleLog(i, BLOG_ERROR, "wrong arity");
          goto fail0;
      }
      if (!NCDVal_IsString(addr_arg) || !NCDVal_IsString(prefix_arg)) {
          ModuleLog(i, BLOG_ERROR, "wrong type");
          goto fail0;
      }
      
      // parse addr
      uint32_t addr;
      if (!ipaddr_parse_ipv4_addr(NCDVal_StringMemRef(addr_arg), &addr)) {
          ModuleLog(i, BLOG_ERROR, "bad addr");
          goto fail0;
      }
      
      // parse prefix
      int prefix;
      if (!ipaddr_parse_ipv4_prefix(NCDVal_StringMemRef(prefix_arg), &prefix)) {
          ModuleLog(i, BLOG_ERROR, "bad prefix");
          goto fail0;
      }
      
      // make network
      uint32_t network = (addr & ipaddr_ipv4_mask_from_prefix(prefix));
      
      addr_func_init_templ(vo, i, network);
      return;
      
  fail0:
      NCDModuleInst_Backend_DeadError(i);
  }
  
  static void addr_func_die (void *vo)
  {
      struct addr_instance *o = vo;
      
      NCDModuleInst_Backend_Dead(o->i);
  }
  
  static int addr_func_getvar2 (void *vo, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out)
  {
      struct addr_instance *o = vo;
      
      if (name == NCD_STRING_EMPTY) {
          char buf[IPADDR_PRINT_MAX];
          ipaddr_print_addr(o->addr, buf);
          
          *out = NCDVal_NewString(mem, buf);
          return 1;
      }
      
      return 0;
  }
  
  static void mask_to_prefix_func_init (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
  {
      struct prefix_instance *o = vo;
      o->i = i;
      
      // read arguments
      NCDValRef mask_arg;
      if (!NCDVal_ListRead(params->args, 1, &mask_arg)) {
          ModuleLog(i, BLOG_ERROR, "wrong arity");
          goto fail0;
      }
      if (!NCDVal_IsString(mask_arg)) {
          ModuleLog(i, BLOG_ERROR, "wrong type");
          goto fail0;
      }
      
      // parse mask
      uint32_t mask;
      if (!ipaddr_parse_ipv4_addr(NCDVal_StringMemRef(mask_arg), &mask)) {
          ModuleLog(i, BLOG_ERROR, "bad mask");
          goto fail0;
      }
      
      // build prefix
      if (!ipaddr_ipv4_prefix_from_mask(mask, &o->prefix)) {
          ModuleLog(i, BLOG_ERROR, "bad mask");
          goto fail0;
      }
      
      // signal up
      NCDModuleInst_Backend_Up(i);
      return;
      
  fail0:
      NCDModuleInst_Backend_DeadError(i);
  }
  
  static void prefix_func_die (void *vo)
  {
      struct prefix_instance *o = vo;
      
      NCDModuleInst_Backend_Dead(o->i);
  }
  
  static int prefix_func_getvar2 (void *vo, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out)
  {
      struct prefix_instance *o = vo;
      
      if (name == NCD_STRING_EMPTY) {
          char buf[6];
          sprintf(buf, "%d", o->prefix);
          
          *out = NCDVal_NewString(mem, buf);
          return 1;
      }
      
      return 0;
  }
  
  static struct NCDModule modules[] = {
      {
          .type = "ipv4_prefix_to_mask",
          .func_new2 = prefix_to_mask_func_init,
          .func_die = addr_func_die,
          .func_getvar2 = addr_func_getvar2,
          .alloc_size = sizeof(struct addr_instance)
      }, {
          .type = "ipv4_mask_to_prefix",
          .func_new2 = mask_to_prefix_func_init,
          .func_die = prefix_func_die,
          .func_getvar2 = prefix_func_getvar2,
          .alloc_size = sizeof(struct prefix_instance)
      }, {
          .type = "ipv4_net_from_addr_and_prefix",
          .func_new2 = ipv4_net_from_addr_and_prefix_func_init,
          .func_die = addr_func_die,
          .func_getvar2 = addr_func_getvar2,
          .alloc_size = sizeof(struct addr_instance)
      }, {
          .type = NULL
      }
  };
  
  const struct NCDModuleGroup ncdmodule_netmask = {
      .modules = modules
  };
  