1  /* Compare two binary domain names for quality.
       2     Copyright (C) 2022-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <arpa/nameser.h>
      20  #include <stdbool.h>
      21  
      22  /* Convert ASCII letters to upper case.  */
      23  static inline int
      24  ascii_toupper (unsigned char ch)
      25  {
      26    if (ch >= 'a' && ch <= 'z')
      27      return ch - 'a' + 'A';
      28    else
      29      return ch;
      30  }
      31  
      32  bool
      33  __ns_samebinaryname (const unsigned char *a, const unsigned char *b)
      34  {
      35    while (*a != 0 && *b != 0)
      36      {
      37        if (*a != *b)
      38          /* Different label length.  */
      39          return false;
      40        int labellen = *a;
      41        ++a;
      42        ++b;
      43        for (int i = 0; i < labellen; ++i)
      44          {
      45            if (*a != *b && ascii_toupper (*a) != ascii_toupper (*b))
      46              /* Different character in label.  */
      47              return false;
      48            ++a;
      49            ++b;
      50          }
      51      }
      52  
      53    /* Match if both names are at the root label.  */
      54    return *a == 0 && *b == 0;
      55  }