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