Commit | Line | Data |
---|---|---|
dc0d77d7 CE |
1 | #include <unistd.h> |
2 | #include "dns.h" | |
3 | #include "taia.h" | |
4 | #include "uint32.h" | |
5 | ||
6 | static uint32 seed[32]; | |
7 | static uint32 in[12]; | |
8 | static uint32 out[8]; | |
9 | static int outleft = 0; | |
10 | ||
11 | #define ROTATE(x,b) (((x) << (b)) | ((x) >> (32 - (b)))) | |
12 | #define MUSH(i,b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x,b)); | |
13 | ||
14 | static void surf(void) | |
15 | { | |
16 | uint32 t[12]; uint32 x; uint32 sum = 0; | |
17 | int r; int i; int loop; | |
18 | ||
19 | for (i = 0;i < 12;++i) t[i] = in[i] ^ seed[12 + i]; | |
20 | for (i = 0;i < 8;++i) out[i] = seed[24 + i]; | |
21 | x = t[11]; | |
22 | for (loop = 0;loop < 2;++loop) { | |
23 | for (r = 0;r < 16;++r) { | |
24 | sum += 0x9e3779b9; | |
25 | MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13) | |
26 | MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13) | |
27 | MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13) | |
28 | } | |
29 | for (i = 0;i < 8;++i) out[i] ^= t[i + 4]; | |
30 | } | |
31 | } | |
32 | ||
33 | void dns_random_init(const char data[128]) | |
34 | { | |
35 | int i; | |
36 | struct taia t; | |
37 | char tpack[16]; | |
38 | ||
39 | for (i = 0;i < 32;++i) | |
40 | uint32_unpack(data + 4 * i,seed + i); | |
41 | ||
42 | taia_now(&t); | |
43 | taia_pack(tpack,&t); | |
44 | for (i = 0;i < 4;++i) | |
45 | uint32_unpack(tpack + 4 * i,in + 4 + i); | |
46 | ||
47 | in[8] = getpid(); | |
48 | in[9] = getppid(); | |
49 | /* more space in 10 and 11, but this is probably enough */ | |
50 | } | |
51 | ||
52 | unsigned int dns_random(unsigned int n) | |
53 | { | |
54 | if (!n) return 0; | |
55 | ||
56 | if (!outleft) { | |
57 | if (!++in[0]) if (!++in[1]) if (!++in[2]) ++in[3]; | |
58 | surf(); | |
59 | outleft = 8; | |
60 | } | |
61 | ||
62 | return out[--outleft] % n; | |
63 | } |