support/support_format_hostent.c

   1 /* Convert a struct hostent object to a string.
   2    Copyright (C) 2016-2017 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <support/format_nss.h>
  20
  21 #include <arpa/inet.h>
  22 #include <stdio.h>
  23 #include <support/support.h>
  24 #include <support/xmemstream.h>
  25
  26 static int
  27 address_length (int family)
  28 {
  29   switch (family)
  30     {
  31     case AF_INET:
  32       return 4;
  33     case AF_INET6:
  34       return 16;
  35     }
  36   return -1;
  37 }
  38
  39 char *
  40 support_format_hostent (struct hostent *h)
  41 {
  42   if (h == NULL)
  43     {
  44       char *value = support_format_herrno (h_errno);
  45       char *result = xasprintf ("error: %s\n", value);
  46       free (value);
  47       return result;
  48     }
  49
  50   struct xmemstream mem;
  51   xopen_memstream (&mem);
  52
  53   fprintf (mem.out, "name: %s\n", h->h_name);
  54   for (char **alias = h->h_aliases; *alias != NULL; ++alias)
  55     fprintf (mem.out, "alias: %s\n", *alias);
  56   for (unsigned i = 0; h->h_addr_list[i] != NULL; ++i)
  57     {
  58       char buf[128];
  59       if (inet_ntop (h->h_addrtype, h->h_addr_list[i],
  60                      buf, sizeof (buf)) == NULL)
  61         fprintf (mem.out, "error: inet_ntop failed: %m\n");
  62       else
  63         fprintf (mem.out, "address: %s\n", buf);
  64     }
  65   if (h->h_length != address_length (h->h_addrtype))
  66     {
  67       char *family = support_format_address_family (h->h_addrtype);
  68       fprintf (mem.out, "error: invalid address length %d for %s\n",
  69                h->h_length, family);
  70       free (family);
  71     }
  72
  73   xfclose_memstream (&mem);
  74   return mem.buffer;
  75 }