summaryrefslogtreecommitdiff
path: root/src/dnsstub/dns_random.c
diff options
context:
space:
mode:
authorJannis Hoffmann <jannis@fehcom.de>2024-07-09 13:58:20 +0200
committerJannis Hoffmann <jannis@fehcom.de>2024-07-09 13:58:20 +0200
commit249866e3d1e11dc72eaa1305f4bb479ded92ef38 (patch)
tree7118c5f58e29fe61c100e4d067bb90ba8d52589e /src/dnsstub/dns_random.c
parent96cf8dffe4f7b0b910f790066ae622dc429eb522 (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.c70
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;
+}