1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
|
/*
GameSpy GT2 SDK
Dan "Mr. Pants" Schoenblum
dan@gamespy.com
Copyright 2002 GameSpy Industries, Inc
devsupport@gamespy.com
*/
#include "gt2Main.h"
#include "gt2Auth.h"
#include <stdlib.h>
#define CALCULATEODDMODE(buffer, i, oddmode) ((buffer[i-1] & 1) ^ (i & 1) ^ oddmode ^ (buffer[0] & 1) ^ ((buffer[0] < 79) ? 1 : 0) ^ ((buffer[i-1] < buffer[0]) ? 1 : 0));
char GT2ChallengeKey[33] = "3b8dd8995f7c40a9a5c5b7dd5b481341";
static int gti2VerifyChallenge(const GT2Byte *buffer)
{
int oddmode = 0;
int i;
for (i = 1; i < GTI2_CHALLENGE_LEN ; i++)
{
oddmode = CALCULATEODDMODE(buffer,i, oddmode);
if ((oddmode && (buffer[i] & 1) == 0) || (!oddmode && ((buffer[i] & 1) == 1)))
return 0; //failed!!
}
return 1;
}
GT2Byte * gti2GetChallenge
(
GT2Byte * buffer
)
{
int i;
int oddmode;
assert(buffer);
srand((unsigned int)current_time());
buffer[0] = (GT2Byte)(33 + rand() % 93); //use chars in the range 33 - 125
oddmode = 0;
for (i = 1; i < GTI2_CHALLENGE_LEN ; i++)
{
oddmode = CALCULATEODDMODE(buffer,i, oddmode);
buffer[i] = (GT2Byte)(33 + rand() % 93); //use chars in the range 33 - 125
//if oddmode make sure the char is odd, otherwise make sure it's even
if ((oddmode && (buffer[i] & 1) == 0) || (!oddmode && ((buffer[i] & 1) == 1)))
buffer[i]++;
}
return buffer;
}
GT2Byte * gti2GetResponse
(
GT2Byte * buffer,
const GT2Byte * challenge
)
{
int i;
int valid;
char cchar;
int keylen = (int)strlen(GT2ChallengeKey);
int chalrand;
valid = gti2VerifyChallenge(challenge); //it's an invalid challenge, give them a bogus response
//assert(GTI2_RESPONSE_LEN <= GTI2_CHALLENGE_LEN);
for (i = 0 ; i < GTI2_RESPONSE_LEN ; i++)
{
//use random vals for spots 0 and 13
if (!valid || i == 0 || i == 13)
buffer[i] = (GT2Byte)(33 + rand() % 93); //use chars in the range 33 - 125
else
{ //set the character to look back at, never use the random ones!
if (i == 1 || i == 14)
cchar = (char)challenge[i];
else
cchar = (char)challenge[i-1];
chalrand = abs((challenge[((i * challenge[i]) + GT2ChallengeKey[(i + challenge[i]) % keylen]) % GTI2_CHALLENGE_LEN] ^ GT2ChallengeKey[(i * 17991 * cchar) % keylen]));
buffer[i] = (GT2Byte)(33 + chalrand % 93);
}
}
return buffer;
}
GT2Bool gti2CheckResponse
(
const GT2Byte * response1,
const GT2Byte * response2
)
{
int i; //when comparing ignore the ones that are random
for (i = 0 ; i < GTI2_RESPONSE_LEN ; i++)
{
if (i != 0 && i != 13 && response1[i] != response2[i])
return GT2False;
}
return GT2True;
}
|
