124 lines
4.2 KiB
C
124 lines
4.2 KiB
C
/****************************************************************************
|
|
* apps/netutils/netlib/netlib_prefix2ipv6netmask.c
|
|
*
|
|
* Copyright (C) 2015 Gregory Nutt. All rights reserved.
|
|
* Author: Gregory Nutt <gnutt@nuttx.org>
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* 3. Neither the name NuttX nor the names of its contributors may be
|
|
* used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
|
|
#include <stdint.h>
|
|
#include <netinet/ip.h>
|
|
|
|
#include <apps/netutils/netlib.h>
|
|
|
|
#ifdef CONFIG_NET_IPv6
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Function: netlib_prefix2ipv6netmask
|
|
*
|
|
* Description:
|
|
* Convert a IPv6 prefix length to a network mask. The prefix length
|
|
* specifies the number of MS bits under mask (0-128)
|
|
*
|
|
* Parameters:
|
|
* preflen - Determines the width of the netmask (in bits). Range 0-128
|
|
* netmask - The location to return the netmask.
|
|
*
|
|
* Returned Value:
|
|
* None
|
|
*
|
|
****************************************************************************/
|
|
|
|
void netlib_prefix2ipv6netmask(uint8_t preflen, FAR struct in6_addr *netmask)
|
|
{
|
|
FAR uint16_t *mask = netmask->s6_addr16;
|
|
unsigned int bit;
|
|
unsigned int i;
|
|
|
|
/* Set the network mask. preflen is the number of MS bits under the mask.
|
|
*
|
|
* Eg. preflen = 38
|
|
* NETMASK: ffff ffff fc00 0000 0000 0000 0000 0000
|
|
* bit: 1 1..1
|
|
* 1 1..3 3..4 4..6 6..7 8..9 9..1 1..2
|
|
* 0..5 6..1 2..7 8..3 4..9 0..5 6..1 2..7
|
|
* preflen: 1 1..1
|
|
* 1 1..3 3..4 4..6 6..8 8..9 9..1 1..2
|
|
* 1..6 7..2 3..8 9..4 5..0 1..6 7..2 3..8
|
|
*/
|
|
|
|
for (i = 0; i < 7; i++)
|
|
{
|
|
/* bit = {0, 16, 32, 48, 64, 80, 96, 112} */
|
|
|
|
bit = i << 4;
|
|
|
|
if (preflen > bit)
|
|
{
|
|
/* Eg. preflen = 38, bit = {0, 16, 32} */
|
|
|
|
if (preflen > (bit + 16))
|
|
{
|
|
/* Eg. preflen = 38, bit = {0, 16} */
|
|
|
|
mask[i] = 0xffff;
|
|
}
|
|
else
|
|
{
|
|
/* Eg. preflen = 38, bit = {32}
|
|
* bit - preflen = 6
|
|
* make = 0xffff << (16-6)
|
|
* = 0xfc00
|
|
*/
|
|
|
|
mask[i] = 0xffff << (16 - (bit - preflen));
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* Eg. preflen=38, bit= {48, 64, 80, 112} */
|
|
|
|
mask[i] = 0x0000;
|
|
}
|
|
}
|
|
}
|
|
|
|
#endif /* CONFIG_NET_IPv6 */
|