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/* runtime-ipv6 - Check that system is able to set IPv6 address.
Copyright (C) 2020-2025 Free Software Foundation, Inc.
This file is part of GNU Inetutils.
GNU Inetutils is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
GNU Inetutils is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see `http://www.gnu.org/licenses/'. */
/* Written by Mats Erik Andersson. */
/* Runtime-ipv6 determines by default whether IPv6 address ::1 can
* be selected. The switch `-6' is identical, whereas `-4' probes
* for 127.0.0.1.
*
* Invocation:
*
* runtime-ipv6 [-4] [-6]
*
* Return value is 0 (zero) when successful, otherwise -1.
* On failure a message is printed to stderr: `IPv# disabled in system'.
*
* By defining the shell environment variable VERBOSE, a short affirmative
* message is printed also in case of successful testing.
*/
#include <config.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#define RESOLVE_OK 0
#define RESOLVE_FAIL -1
/* The default action is to investigate localhost as IPv6. */
int tested_family = AF_INET6;
char *tested_family_name = "IPv6";
char *tested_localhost = "::1";
int
main (int argc, char *argv[])
{
int err, ch;
struct addrinfo hints, *aiptr;
while ((ch = getopt (argc, argv, "46")) != -1)
{
switch (ch)
{
case '4':
tested_family = AF_INET;
tested_family_name = "IPv4";
tested_localhost = "127.0.0.1";
break;
case '6':
tested_family = AF_INET6;
tested_family_name = "IPv6";
tested_localhost = "::1";
break;
default:
fprintf (stderr, "Usage: %s [-4 | -6]\n"
"Determines presence of selected INET address family.\n",
argv[0]);
return EXIT_FAILURE;
}
}
memset (&hints, 0, sizeof (hints));
hints.ai_family = tested_family;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_NUMERICHOST | AI_NUMERICSERV;
#ifdef AI_ADDRCONFIG
hints.ai_flags |= AI_ADDRCONFIG;
#endif
err = getaddrinfo (tested_localhost, "1237", &hints, &aiptr);
if (!err)
{
/* Should not really happen. */
if (aiptr == NULL)
#ifdef EAI_NODATA
err = EAI_NODATA;
#else
err = EAI_FAIL;
#endif
freeaddrinfo (aiptr);
}
if (err)
{
/* Not able to select localhost as IPv6. */
fprintf (stderr, "%s is disabled in this running system: \"%s\" %s\n",
tested_family_name, tested_localhost, gai_strerror (err));
return RESOLVE_FAIL;
}
else if (getenv ("VERBOSE"))
printf ("Detection of %s address %s was successful.\n",
tested_family_name, tested_localhost);
return RESOLVE_OK;
}
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