On 01/16/2012 10:31 AM, Steinar H. Gunderson wrote:
On Sun, Jan 15, 2012 at 05:11:14PM +0100, Christian Grothoff wrote:
0.4.6? You got to be kidding me. We're at 0.9.17, 0.4.6 is about 2
years old.
That's the joy of being on Debian stable, I guess :-)
More importantly, the patch is overall not taking the
code in the right direction. The modern, recommended way to do
dual-stack IPv6 is what MHD already supports: use two listen
sockets.
I don't know who's been recommending this, but it's certainly not the
majority opinion in the Internet community at large. However, I guess trying
to convince you would not be a very productive endeavor -- it's a contendable
point, and it's your code.
IPv4-compatible IPv6 addresses are used for the dualstack sockets you
propose to use:
http://tools.ietf.org/html/rfc3493#page-22
But, IPv4-compatible IPv6 addresses are now deprecated:
http://tools.ietf.org/html/rfc4291#section-2.5.5
Also, as discussed here
http://stackoverflow.com/questions/2693709/what-was-the-motivation-for-adding-the-ipv6-v6only-flag
you will find that "Specifically Windows XP/2003 does not support
dualstack sockets."
So for portability, having two sockets and using IPV6_ONLY is a good
idea as well.
In conclusion, I cannot show that my decision is the "majority" of the
Internet community at large (I'm pretty sure the majority has no opinion
on this technical detail), but it is well-founded and in line with IETF
recommendations.
How would using two sockets look like from a client's point of view?
Do you have an API example?
Now I do. I've modified the "minimal_example.c" from src/examples/ to
make it dual-stack. As you can see, the changes are trivial.
Happy hacking,
-Christian
/*
This file is part of libmicrohttpd
(C) 2007, 2012 Christian Grothoff (and other contributing authors)
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file dual_stack_example.c
* @brief how to use MHD with both IPv4 and IPv6 support (dual-stack)
* @author Christian Grothoff
*/
#include "platform.h"
#include <microhttpd.h>
#define PAGE "<html><head><title>libmicrohttpd demo</title></head><body>libmicrohttpd demo</body></html>"
static int
ahc_echo (void *cls,
struct MHD_Connection *connection,
const char *url,
const char *method,
const char *version,
const char *upload_data, size_t *upload_data_size, void **ptr)
{
static int aptr;
const char *me = cls;
struct MHD_Response *response;
int ret;
if (0 != strcmp (method, "GET"))
return MHD_NO; /* unexpected method */
if (&aptr != *ptr)
{
/* do never respond on first call */
*ptr = &aptr;
return MHD_YES;
}
*ptr = NULL; /* reset when done */
response = MHD_create_response_from_buffer (strlen (me),
(void *) me,
MHD_RESPMEM_PERSISTENT);
ret = MHD_queue_response (connection, MHD_HTTP_OK, response);
MHD_destroy_response (response);
return ret;
}
int
main (int argc, char *const *argv)
{
struct MHD_Daemon *d4;
struct MHD_Daemon *d6;
if (argc != 2)
{
printf ("%s PORT\n", argv[0]);
return 1;
}
d4 = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY | MHD_USE_DEBUG,
atoi (argv[1]),
NULL, NULL, &ahc_echo, PAGE,
MHD_OPTION_CONNECTION_TIMEOUT, (unsigned int) 120,
MHD_OPTION_END);
d6 = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY | MHD_USE_DEBUG | MHD_USE_IPv6,
atoi (argv[1]),
NULL, NULL, &ahc_echo, PAGE,
MHD_OPTION_CONNECTION_TIMEOUT, (unsigned int) 120,
MHD_OPTION_END);
(void) getc (stdin);
MHD_stop_daemon (d4);
MHD_stop_daemon (d6);
return 0;
}
