forked from osmocom/wireshark
96 lines
2.2 KiB
C
96 lines
2.2 KiB
C
/* addr_and_mask.c
|
|
* Routines to fetch IPv4 and IPv6 addresses from a tvbuff and then mask
|
|
* out bits other than those covered by a prefix length
|
|
*
|
|
* Wireshark - Network traffic analyzer
|
|
* By Gerald Combs <gerald@wireshark.org>
|
|
* Copyright 1998 Gerald Combs
|
|
*
|
|
* SPDX-License-Identifier: GPL-2.0-or-later
|
|
*/
|
|
|
|
#include "config.h"
|
|
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
|
|
#include "tvbuff.h"
|
|
#include "ipv6.h"
|
|
#include "addr_and_mask.h"
|
|
#include <wsutil/ws_assert.h>
|
|
|
|
guint32
|
|
ip_get_subnet_mask(const guint32 mask_length)
|
|
{
|
|
static const guint32 masks[33] = {
|
|
0x00000000,
|
|
0x80000000, 0xc0000000, 0xe0000000, 0xf0000000,
|
|
0xf8000000, 0xfc000000, 0xfe000000, 0xff000000,
|
|
0xff800000, 0xffc00000, 0xffe00000, 0xfff00000,
|
|
0xfff80000, 0xfffc0000, 0xfffe0000, 0xffff0000,
|
|
0xffff8000, 0xffffc000, 0xffffe000, 0xfffff000,
|
|
0xfffff800, 0xfffffc00, 0xfffffe00, 0xffffff00,
|
|
0xffffff80, 0xffffffc0, 0xffffffe0, 0xfffffff0,
|
|
0xfffffff8, 0xfffffffc, 0xfffffffe, 0xffffffff,
|
|
};
|
|
|
|
ws_assert(mask_length <= 32);
|
|
|
|
return masks[mask_length];
|
|
}
|
|
|
|
/*
|
|
* These routines return the length of the address in bytes on success
|
|
* and -1 if the prefix length is too long.
|
|
*/
|
|
|
|
int
|
|
tvb_get_ipv4_addr_with_prefix_len(tvbuff_t *tvb, int offset, ws_in4_addr *addr,
|
|
guint32 prefix_len)
|
|
{
|
|
guint8 addr_len;
|
|
|
|
if (prefix_len > 32)
|
|
return -1;
|
|
|
|
addr_len = (prefix_len + 7) / 8;
|
|
*addr = 0;
|
|
tvb_memcpy(tvb, addr, offset, addr_len);
|
|
if (prefix_len % 8)
|
|
((guint8*)addr)[addr_len - 1] &= ((0xff00 >> (prefix_len % 8)) & 0xff);
|
|
return addr_len;
|
|
}
|
|
|
|
int
|
|
tvb_get_ipv6_addr_with_prefix_len(tvbuff_t *tvb, int offset, ws_in6_addr *addr,
|
|
guint32 prefix_len)
|
|
{
|
|
guint32 addr_len;
|
|
|
|
if (prefix_len > 128)
|
|
return -1;
|
|
|
|
addr_len = (prefix_len + 7) / 8;
|
|
memset(addr->bytes, 0, 16);
|
|
tvb_memcpy(tvb, addr->bytes, offset, addr_len);
|
|
if (prefix_len % 8) {
|
|
addr->bytes[addr_len - 1] &=
|
|
((0xff00 >> (prefix_len % 8)) & 0xff);
|
|
}
|
|
|
|
return addr_len;
|
|
}
|
|
|
|
/*
|
|
* Editor modelines - https://www.wireshark.org/tools/modelines.html
|
|
*
|
|
* Local variables:
|
|
* c-basic-offset: 8
|
|
* tab-width: 8
|
|
* indent-tabs-mode: t
|
|
* End:
|
|
*
|
|
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
|
|
* :indentSize=8:tabSize=8:noTabs=false:
|
|
*/
|