inet/ether_line.c

   1 /* Copyright (C) 1996-2023 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <ctype.h>
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <netinet/ether.h>
  22 #include <netinet/if_ether.h>
  23
  24
  25 int
  26 ether_line (const char *line, struct ether_addr *addr, char *hostname)
  27 {
  28   for (size_t cnt = 0; cnt < 6; ++cnt)
  29     {
  30       unsigned int number;
  31       char ch;
  32
  33       ch = _tolower (*line++);
  34       if ((ch < '0' || ch > '9') && (ch < 'a' || ch > 'f'))
  35         return -1;
  36       number = isdigit (ch) ? (ch - '0') : (ch - 'a' + 10);
  37
  38       ch = _tolower (*line);
  39       if ((cnt < 5 && ch != ':') || (cnt == 5 && ch != '\0' && !isspace (ch)))
  40         {
  41           ++line;
  42           if ((ch < '0' || ch > '9') && (ch < 'a' || ch > 'f'))
  43             return -1;
  44           number <<= 4;
  45           number += isdigit (ch) ? (ch - '0') : (ch - 'a' + 10);
  46
  47           ch = *line;
  48           if (cnt < 5 && ch != ':')
  49             return -1;
  50         }
  51
  52       /* Store result.  */
  53       addr->ether_addr_octet[cnt] = (unsigned char) number;
  54
  55       /* Skip ':'.  */
  56       if (ch != '\0')
  57         ++line;
  58     }
  59
  60   /* Skip initial whitespace.  */
  61   while (isspace (*line))
  62     ++line;
  63
  64   if (*line == '#' || *line == '\0')
  65     /* No hostname.  */
  66     return -1;
  67
  68   /* The hostname is up to the next non-space character.  */
  69   /* XXX This can cause trouble because the hostname might be too long
  70      but we have no possibility to check it here.  */
  71   while (*line != '\0' && *line != '#' && !isspace (*line))
  72     *hostname++ = *line++;
  73   *hostname = '\0';
  74
  75   return 0;
  76 }