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 #include <libloc/compat.h>
  26
  27 #define LOC_ADDRESS_BUFFERS                             6
  28 #define LOC_ADDRESS_BUFFER_LENGTH               INET6_ADDRSTRLEN
  29
  30 static char __loc_address_buffers[LOC_ADDRESS_BUFFERS][LOC_ADDRESS_BUFFER_LENGTH + 1];
  31 static int  __loc_address_buffer_idx = 0;
  32
  33 static const char* __loc_address6_str(const struct in6_addr* address, char* buffer, size_t length) {
  34         return inet_ntop(AF_INET6, address, buffer, length);
  35 }
  36
  37 static const char* __loc_address4_str(const struct in6_addr* address, char* buffer, size_t length) {
  38         struct in_addr address4 = {
  39                 .s_addr = address->s6_addr32[3],
  40         };
  41
  42         return inet_ntop(AF_INET, &address4, buffer, length);
  43 }
  44
  45 const char* loc_address_str(const struct in6_addr* address) {
  46         if (!address)
  47                 return NULL;
  48
  49         // Select buffer
  50         char* buffer = __loc_address_buffers[__loc_address_buffer_idx++];
  51
  52         // Prevent index from overflow
  53         __loc_address_buffer_idx %= LOC_ADDRESS_BUFFERS;
  54
  55         if (IN6_IS_ADDR_V4MAPPED(address))
  56                 return __loc_address4_str(address, buffer, LOC_ADDRESS_BUFFER_LENGTH);
  57         else
  58                 return __loc_address6_str(address, buffer, LOC_ADDRESS_BUFFER_LENGTH);
  59 }
  60
  61 static void loc_address_from_address4(struct in6_addr* address,
  62                 const struct in_addr* address4) {
  63         address->s6_addr32[0] = 0;
  64         address->s6_addr32[1] = 0;
  65         address->s6_addr32[2] = htonl(0xffff);
  66         address->s6_addr32[3] = address4->s_addr;
  67 }
  68
  69 int loc_address_parse(struct in6_addr* address, unsigned int* prefix, const char* string) {
  70         char buffer[INET6_ADDRSTRLEN + 4];
  71         int r;
  72
  73         if (!address || !string) {
  74                 errno = EINVAL;
  75                 return 1;
  76         }
  77
  78         // Copy the string into the buffer
  79         r = snprintf(buffer, sizeof(buffer) - 1, "%s", string);
  80         if (r < 0)
  81                 return 1;
  82
  83         // Find /
  84         char* p = strchr(buffer, '/');
  85         if (p) {
  86                 // Terminate the IP address
  87                 *p++ = '\0';
  88         }
  89
  90         int family = AF_UNSPEC;
  91
  92         // Try parsing as an IPv6 address
  93         r = inet_pton(AF_INET6, buffer, address);
  94         switch (r) {
  95                 // This is not a valid IPv6 address
  96                 case 0:
  97                         break;
  98
  99                 // This is a valid IPv6 address
 100                 case 1:
 101                         family = AF_INET6;
 102                         break;
 103
 104                 // Unexpected error
 105                 default:
 106                         return 1;
 107         }
 108
 109         // Try parsing as an IPv4 address
 110         if (!family) {
 111                 struct in_addr address4;
 112
 113                 r = inet_pton(AF_INET, buffer, &address4);
 114                 switch (r) {
 115                         // This was not a valid IPv4 address
 116                         case 0:
 117                                 break;
 118
 119                         // This was a valid IPv4 address
 120                         case 1:
 121                                 family = AF_INET;
 122
 123                                 // Copy the result
 124                                 loc_address_from_address4(address, &address4);
 125                                 break;
 126
 127                         // Unexpected error
 128                         default:
 129                                 return 1;
 130                 }
 131         }
 132
 133         // Invalid input
 134         if (family == AF_UNSPEC) {
 135                 errno = EINVAL;
 136                 return 1;
 137         }
 138
 139         // Did the user request a prefix?
 140         if (prefix) {
 141                 // Set the prefix to the default value
 142                 const unsigned int max_prefix = loc_address_family_bit_length(family);
 143
 144                 // Parse the actual string
 145                 if (p) {
 146                         *prefix = strtol(p, NULL, 10);
 147
 148                         // Check if prefix is within bounds
 149                         if (*prefix > max_prefix) {
 150                                 errno = EINVAL;
 151                                 return 1;
 152                         }
 153
 154                 // If the string didn't contain a prefix, we set the maximum
 155                 } else {
 156                         *prefix = max_prefix;
 157                 }
 158         }
 159
 160         return 0;
 161 }