src/address.c

   1 /*
   2         libloc - A library to determine the location of someone on the Internet
   3
   4         Copyright (C) 2022 IPFire Development Team <info@ipfire.org>
   5
   6         This library is free software; you can redistribute it and/or
   7         modify it under the terms of the GNU Lesser General Public
   8         License as published by the Free Software Foundation; either
   9         version 2.1 of the License, or (at your option) any later version.
  10
  11         This library is distributed in the hope that it will be useful,
  12         but WITHOUT ANY WARRANTY; without even the implied warranty of
  13         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14         Lesser General Public License for more details.
  15 */
  16
  17 #include <arpa/inet.h>
  18 #include <netinet/in.h>
  19 #include <stddef.h>
  20
  21 #include <libloc/address.h>
  22
  23 #define LOC_ADDRESS_BUFFERS                             6
  24 #define LOC_ADDRESS_BUFFER_LENGTH               INET6_ADDRSTRLEN
  25
  26 static char __loc_address_buffers[LOC_ADDRESS_BUFFER_LENGTH + 1][LOC_ADDRESS_BUFFERS];
  27 static int  __loc_address_buffer_idx = 0;
  28
  29 static const char* __loc_address6_str(const struct in6_addr* address, char* buffer, size_t length) {
  30         return inet_ntop(AF_INET6, address, buffer, length);
  31 }
  32
  33 static const char* __loc_address4_str(const struct in6_addr* address, char* buffer, size_t length) {
  34         struct in_addr address4 = {
  35                 .s_addr = address->s6_addr32[3],
  36         };
  37
  38         return inet_ntop(AF_INET, &address4, buffer, length);
  39 }
  40
  41 const char* loc_address_str(const struct in6_addr* address) {
  42         if (!address)
  43                 return NULL;
  44
  45         // Select buffer
  46         char* buffer = __loc_address_buffers[__loc_address_buffer_idx++];
  47
  48         // Prevent index from overflow
  49         __loc_address_buffer_idx %= LOC_ADDRESS_BUFFERS;
  50
  51         if (IN6_IS_ADDR_V4MAPPED(address))
  52                 return __loc_address4_str(address, buffer, LOC_ADDRESS_BUFFER_LENGTH);
  53         else
  54                 return __loc_address6_str(address, buffer, LOC_ADDRESS_BUFFER_LENGTH);
  55 }