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Diffstat (limited to 'openvpn/tap-win32/macinfo.c')
| -rwxr-xr-x | openvpn/tap-win32/macinfo.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/openvpn/tap-win32/macinfo.c b/openvpn/tap-win32/macinfo.c new file mode 100755 index 0000000..bc75f3d --- /dev/null +++ b/openvpn/tap-win32/macinfo.c @@ -0,0 +1,158 @@ +/* + * TAP-Win32 -- A kernel driver to provide virtual tap device functionality + * on Windows. Originally derived from the CIPE-Win32 + * project by Damion K. Wilson, with extensive modifications by + * James Yonan. + * + * All source code which derives from the CIPE-Win32 project is + * Copyright (C) Damion K. Wilson, 2003, and is released under the + * GPL version 2 (see below). + * + * All other source code is Copyright (C) 2002-2005 OpenVPN Solutions LLC, + * 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; +} |