diff options
author | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 13:58:20 +0200 |
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committer | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 13:58:20 +0200 |
commit | 249866e3d1e11dc72eaa1305f4bb479ded92ef38 (patch) | |
tree | 7118c5f58e29fe61c100e4d067bb90ba8d52589e /src/dnsstub/dns_random.c | |
parent | 96cf8dffe4f7b0b910f790066ae622dc429eb522 (diff) |
reorganized file structure
Moved c files into src/.
Corrected VERSION file.
Removed BUILD and FILES.
Diffstat (limited to 'src/dnsstub/dns_random.c')
-rw-r--r-- | src/dnsstub/dns_random.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/src/dnsstub/dns_random.c b/src/dnsstub/dns_random.c new file mode 100644 index 0000000..200cd6c --- /dev/null +++ b/src/dnsstub/dns_random.c @@ -0,0 +1,70 @@ +#include <unistd.h> +#include "taia.h" +#include "uint_t.h" +#include "dnsresolv.h" + +/** + @file dns_random.c + @author djb + @source ucspi-tcp + @brief random use of DNS resolvers given their IP +*/ + +static uint32 seed[32]; +static uint32 in[12]; +static uint32 out[8]; +static int outleft = 0; + +#define ROTATE(x,b) (((x) << (b)) | ((x) >> (32 - (b)))) +#define MUSH(i,b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x,b)); + +static void surf(void) +{ + uint32 t[12]; uint32 x; uint32 sum = 0; + int r; int i; int loop; + + for (i = 0; i < 12; ++i) t[i] = in[i] ^ seed[12 + i]; + for (i = 0; i < 8; ++i) out[i] = seed[24 + i]; + x = t[11]; + for (loop = 0; loop < 2; ++loop) { + for (r = 0; r < 16; ++r) { + sum += 0x9e3779b9; + MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13) + MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13) + MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13) + } + for (i = 0; i < 8; ++i) out[i] ^= t[i + 4]; + } +} + +void dns_random_init(const char data[128]) +{ + int i; + struct taia t; + char tpack[16]; + + for (i = 0; i < 32; ++i) + uint32_unpack((char *)data + 4 * i,seed + i); + + taia_now(&t); + taia_pack(tpack,&t); + for (i = 0; i < 4; ++i) + uint32_unpack(tpack + 4 * i,in + 4 + i); + + in[8] = getpid(); + in[9] = getppid(); + /* more space in 10 and 11, but this is probably enough */ +} + +unsigned int dns_random(unsigned int n) +{ + if (!n) return 0; + + if (!outleft) { + if (!++in[0]) if (!++in[1]) if (!++in[2]) ++in[3]; + surf(); + outleft = 8; + } + + return out[--outleft] % n; +} |