src/basic/ether-addr-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2014 Tom Gundersen
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   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   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <net/ethernet.h>
  21 #include <stdio.h>
  22 #include <sys/types.h>
  23
  24 #include "ether-addr-util.h"
  25 #include "macro.h"
  26 #include "string-util.h"
  27
  28 char* ether_addr_to_string(const struct ether_addr *addr, char buffer[ETHER_ADDR_TO_STRING_MAX]) {
  29         assert(addr);
  30         assert(buffer);
  31
  32         /* Like ether_ntoa() but uses %02x instead of %x to print
  33          * ethernet addresses, which makes them look less funny. Also,
  34          * doesn't use a static buffer. */
  35
  36         sprintf(buffer, "%02x:%02x:%02x:%02x:%02x:%02x",
  37                 addr->ether_addr_octet[0],
  38                 addr->ether_addr_octet[1],
  39                 addr->ether_addr_octet[2],
  40                 addr->ether_addr_octet[3],
  41                 addr->ether_addr_octet[4],
  42                 addr->ether_addr_octet[5]);
  43
  44         return buffer;
  45 }
  46
  47 bool ether_addr_equal(const struct ether_addr *a, const struct ether_addr *b) {
  48         assert(a);
  49         assert(b);
  50
  51         return  a->ether_addr_octet[0] == b->ether_addr_octet[0] &&
  52                 a->ether_addr_octet[1] == b->ether_addr_octet[1] &&
  53                 a->ether_addr_octet[2] == b->ether_addr_octet[2] &&
  54                 a->ether_addr_octet[3] == b->ether_addr_octet[3] &&
  55                 a->ether_addr_octet[4] == b->ether_addr_octet[4] &&
  56                 a->ether_addr_octet[5] == b->ether_addr_octet[5];
  57 }
  58
  59 int ether_addr_from_string(const char *s, struct ether_addr *ret, size_t *offset) {
  60         size_t pos = 0, n, field;
  61         char sep = '\0';
  62         const char *hex = HEXDIGITS, *hexoff;
  63         size_t x;
  64         bool touched;
  65
  66 #define parse_fields(v)                                         \
  67         for (field = 0; field < ELEMENTSOF(v); field++) {       \
  68                 touched = false;                                \
  69                 for (n = 0; n < (2 * sizeof(v[0])); n++) {      \
  70                         if (s[pos] == '\0')                     \
  71                                 break;                          \
  72                         hexoff = strchr(hex, s[pos]);           \
  73                         if (hexoff == NULL)                     \
  74                                 break;                          \
  75                         assert(hexoff >= hex);                  \
  76                         x = hexoff - hex;                       \
  77                         if (x >= 16)                            \
  78                                 x -= 6; /* A-F */               \
  79                         assert(x < 16);                         \
  80                         touched = true;                         \
  81                         v[field] <<= 4;                         \
  82                         v[field] += x;                          \
  83                         pos++;                                  \
  84                 }                                               \
  85                 if (!touched)                                   \
  86                         return -EINVAL;                         \
  87                 if (field < (ELEMENTSOF(v)-1)) {                \
  88                         if (s[pos] != sep)                      \
  89                                 return -EINVAL;                 \
  90                         else                                    \
  91                                 pos++;                          \
  92                 }                                               \
  93         }
  94
  95         assert(s);
  96         assert(ret);
  97
  98         sep = s[strspn(s, hex)];
  99         if (sep == '\n')
 100                 return -EINVAL;
 101         if (strchr(":.-", sep) == NULL)
 102                 return -EINVAL;
 103
 104         if (sep == '.') {
 105                 uint16_t shorts[3] = { 0 };
 106
 107                 parse_fields(shorts);
 108
 109                 for (n = 0; n < ELEMENTSOF(shorts); n++) {
 110                         ret->ether_addr_octet[2*n] = ((shorts[n] & (uint16_t)0xff00) >> 8);
 111                         ret->ether_addr_octet[2*n + 1] = (shorts[n] & (uint16_t)0x00ff);
 112                 }
 113         } else {
 114                 struct ether_addr out = { .ether_addr_octet = { 0 } };
 115
 116                 parse_fields(out.ether_addr_octet);
 117
 118                 for (n = 0; n < ELEMENTSOF(out.ether_addr_octet); n++)
 119                         ret->ether_addr_octet[n] = out.ether_addr_octet[n];
 120         }
 121
 122         if (offset)
 123                 *offset = pos;
 124         return 0;
 125 }