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/*
* TAP-Win32/TAP-Win64 -- A kernel driver to provide virtual tap
* device functionality on Windows.
*
* This code was inspired by the CIPE-Win32 driver by Damion K. Wilson.
*
* This source code is Copyright (C) 2002-2010 OpenVPN Technologies, Inc.,
* and is released under the GPL version 2 (see below).
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program 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 (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "macinfo.h"
int
HexStringToDecimalInt (const int p_Character)
{
int l_Value = 0;
if (p_Character >= 'A' && p_Character <= 'F')
l_Value = (p_Character - 'A') + 10;
else if (p_Character >= 'a' && p_Character <= 'f')
l_Value = (p_Character - 'a') + 10;
else if (p_Character >= '0' && p_Character <= '9')
l_Value = p_Character - '0';
return l_Value;
}
BOOLEAN
ParseMAC (MACADDR dest, const char *src)
{
int c;
int mac_index = 0;
BOOLEAN high_digit = FALSE;
int delim_action = 1;
MYASSERT (src);
MYASSERT (dest);
CLEAR_MAC (dest);
while (c = *src++)
{
if (IsMacDelimiter (c))
{
mac_index += delim_action;
high_digit = FALSE;
delim_action = 1;
}
else if (IsHexDigit (c))
{
const int digit = HexStringToDecimalInt (c);
if (mac_index < sizeof (MACADDR))
{
if (!high_digit)
{
dest[mac_index] = (char)(digit);
high_digit = TRUE;
delim_action = 1;
}
else
{
dest[mac_index] = (char)(dest[mac_index] * 16 + digit);
++mac_index;
high_digit = FALSE;
delim_action = 0;
}
}
else
return FALSE;
}
else
return FALSE;
}
return (mac_index + delim_action) >= sizeof (MACADDR);
}
/*
* Generate a MAC using the GUID in the adapter name.
*
* The mac is constructed as 00:FF:xx:xx:xx:xx where
* the Xs are taken from the first 32 bits of the GUID in the
* adapter name. This is similar to the Linux 2.4 tap MAC
* generator, except linux uses 32 random bits for the Xs.
*
* In general, this solution is reasonable for most
* applications except for very large bridged TAP networks,
* where the probability of address collisions becomes more
* than infintesimal.
*
* Using the well-known "birthday paradox", on a 1000 node
* network the probability of collision would be
* 0.000116292153. On a 10,000 node network, the probability
* of collision would be 0.01157288998621678766.
*/
VOID GenerateRandomMac (MACADDR mac, const unsigned char *adapter_name)
{
unsigned const char *cp = adapter_name;
unsigned char c;
unsigned int i = 2;
unsigned int byte = 0;
int brace = 0;
int state = 0;
CLEAR_MAC (mac);
mac[0] = 0x00;
mac[1] = 0xFF;
while (c = *cp++)
{
if (i >= sizeof (MACADDR))
break;
if (c == '{')
brace = 1;
if (IsHexDigit (c) && brace)
{
const unsigned int digit = HexStringToDecimalInt (c);
if (state)
{
byte <<= 4;
byte |= digit;
mac[i++] = (unsigned char) byte;
state = 0;
}
else
{
byte = digit;
state = 1;
}
}
}
}
VOID GenerateRelatedMAC (MACADDR dest, const MACADDR src, const int delta)
{
COPY_MAC (dest, src);
dest[2] += (UCHAR) delta;
}
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