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 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23
  24 #include <libloc/address.h>
  25
  26 #define LOC_ADDRESS_BUFFERS                             6
  27 #define LOC_ADDRESS_BUFFER_LENGTH               INET6_ADDRSTRLEN
  28
  29 static char __loc_address_buffers[LOC_ADDRESS_BUFFERS][LOC_ADDRESS_BUFFER_LENGTH + 1];
  30 static int  __loc_address_buffer_idx = 0;
  31
  32 static const char* __loc_address6_str(const struct in6_addr* address, char* buffer, size_t length) {
  33         return inet_ntop(AF_INET6, address, buffer, length);
  34 }
  35
  36 static const char* __loc_address4_str(const struct in6_addr* address, char* buffer, size_t length) {
  37         struct in_addr address4 = {
  38                 .s_addr = address->s6_addr32[3],
  39         };
  40
  41         return inet_ntop(AF_INET, &address4, buffer, length);
  42 }
  43
  44 const char* loc_address_str(const struct in6_addr* address) {
  45         if (!address)
  46                 return NULL;
  47
  48         // Select buffer
  49         char* buffer = __loc_address_buffers[__loc_address_buffer_idx++];
  50
  51         // Prevent index from overflow
  52         __loc_address_buffer_idx %= LOC_ADDRESS_BUFFERS;
  53
  54         if (IN6_IS_ADDR_V4MAPPED(address))
  55                 return __loc_address4_str(address, buffer, LOC_ADDRESS_BUFFER_LENGTH);
  56         else
  57                 return __loc_address6_str(address, buffer, LOC_ADDRESS_BUFFER_LENGTH);
  58 }
  59
  60 static void loc_address_from_address4(struct in6_addr* address,
  61                 const struct in_addr* address4) {
  62         address->s6_addr32[0] = 0;
  63         address->s6_addr32[1] = 0;
  64         address->s6_addr32[2] = htonl(0xffff);
  65         address->s6_addr32[3] = address4->s_addr;
  66 }
  67
  68 int loc_address_parse(struct in6_addr* address, unsigned int* prefix, const char* string) {
  69         char buffer[INET6_ADDRSTRLEN + 4];
  70         int r;
  71
  72         if (!address || !string) {
  73                 errno = EINVAL;
  74                 return 1;
  75         }
  76
  77         // Copy the string into the buffer
  78         r = snprintf(buffer, sizeof(buffer) - 1, "%s", string);
  79         if (r < 0)
  80                 return 1;
  81
  82         // Find /
  83         char* p = strchr(buffer, '/');
  84         if (p) {
  85                 // Terminate the IP address
  86                 *p++ = '\0';
  87         }
  88
  89         int family = AF_UNSPEC;
  90
  91         // Try parsing as an IPv6 address
  92         r = inet_pton(AF_INET6, buffer, address);
  93         switch (r) {
  94                 // This is not a valid IPv6 address
  95                 case 0:
  96                         break;
  97
  98                 // This is a valid IPv6 address
  99                 case 1:
 100                         family = AF_INET6;
 101                         break;
 102
 103                 // Unexpected error
 104                 default:
 105                         return 1;
 106         }
 107
 108         // Try parsing as an IPv4 address
 109         if (!family) {
 110                 struct in_addr address4;
 111
 112                 r = inet_pton(AF_INET, buffer, &address4);
 113                 switch (r) {
 114                         // This was not a valid IPv4 address
 115                         case 0:
 116                                 break;
 117
 118                         // This was a valid IPv4 address
 119                         case 1:
 120                                 family = AF_INET;
 121
 122                                 // Copy the result
 123                                 loc_address_from_address4(address, &address4);
 124                                 break;
 125
 126                         // Unexpected error
 127                         default:
 128                                 return 1;
 129                 }
 130         }
 131
 132         // Invalid input
 133         if (family == AF_UNSPEC) {
 134                 errno = EINVAL;
 135                 return 1;
 136         }
 137
 138         // Did the user request a prefix?
 139         if (prefix) {
 140                 // Set the prefix to the default value
 141                 *prefix = loc_address_family_bit_length(family);
 142
 143                 // Parse the actual string
 144                 if (p)
 145                         *prefix = strtol(p, NULL, 10);
 146         }
 147
 148         return 0;
 149 }