support/support_format_hostent.c

   1 /* Convert a struct hostent object to a string.
   2    Copyright (C) 2016-2023 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 <support/format_nss.h>
  20
  21 #include <arpa/inet.h>
  22 #include <errno.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <support/support.h>
  26 #include <support/xmemstream.h>
  27
  28 static int
  29 address_length (int family)
  30 {
  31   switch (family)
  32     {
  33     case AF_INET:
  34       return 4;
  35     case AF_INET6:
  36       return 16;
  37     }
  38   return -1;
  39 }
  40
  41 char *
  42 support_format_hostent (struct hostent *h)
  43 {
  44   if (h == NULL)
  45     {
  46       if (h_errno == NETDB_INTERNAL)
  47         return xasprintf ("error: NETDB_INTERNAL (errno %d, %m)\n", errno);
  48       else
  49         {
  50           char *value = support_format_herrno (h_errno);
  51           char *result = xasprintf ("error: %s\n", value);
  52           free (value);
  53           return result;
  54         }
  55     }
  56
  57   struct xmemstream mem;
  58   xopen_memstream (&mem);
  59
  60   fprintf (mem.out, "name: %s\n", h->h_name);
  61   for (char **alias = h->h_aliases; *alias != NULL; ++alias)
  62     fprintf (mem.out, "alias: %s\n", *alias);
  63   for (unsigned i = 0; h->h_addr_list[i] != NULL; ++i)
  64     {
  65       char buf[128];
  66       if (inet_ntop (h->h_addrtype, h->h_addr_list[i],
  67                      buf, sizeof (buf)) == NULL)
  68         fprintf (mem.out, "error: inet_ntop failed: %m\n");
  69       else
  70         fprintf (mem.out, "address: %s\n", buf);
  71     }
  72   if (h->h_length != address_length (h->h_addrtype))
  73     {
  74       char *family = support_format_address_family (h->h_addrtype);
  75       fprintf (mem.out, "error: invalid address length %d for %s\n",
  76                h->h_length, family);
  77       free (family);
  78     }
  79
  80   xfclose_memstream (&mem);
  81   return mem.buffer;
  82 }