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64 lines
1.3 KiB
C
64 lines
1.3 KiB
C
#include <unistd.h>
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#include "dns.h"
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#include "taia.h"
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#include "uint32.h"
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static uint32 seed[32];
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static uint32 in[12];
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static uint32 out[8];
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static int outleft = 0;
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#define ROTATE(x,b) (((x) << (b)) | ((x) >> (32 - (b))))
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#define MUSH(i,b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x,b));
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static void surf(void)
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{
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uint32 t[12]; uint32 x; uint32 sum = 0;
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int r; int i; int loop;
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for (i = 0;i < 12;++i) t[i] = in[i] ^ seed[12 + i];
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for (i = 0;i < 8;++i) out[i] = seed[24 + i];
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x = t[11];
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for (loop = 0;loop < 2;++loop) {
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for (r = 0;r < 16;++r) {
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sum += 0x9e3779b9;
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MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13)
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MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13)
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MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13)
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}
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for (i = 0;i < 8;++i) out[i] ^= t[i + 4];
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}
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}
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void dns_random_init(const char data[128])
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{
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int i;
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struct taia t;
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char tpack[16];
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for (i = 0;i < 32;++i)
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uint32_unpack(data + 4 * i,seed + i);
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taia_now(&t);
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taia_pack(tpack,&t);
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for (i = 0;i < 4;++i)
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uint32_unpack(tpack + 4 * i,in + 4 + i);
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in[8] = getpid();
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in[9] = getppid();
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/* more space in 10 and 11, but this is probably enough */
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}
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unsigned int dns_random(unsigned int n)
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{
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if (!n) return 0;
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if (!outleft) {
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if (!++in[0]) if (!++in[1]) if (!++in[2]) ++in[3];
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surf();
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outleft = 8;
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}
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return out[--outleft] % n;
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}
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