correct non-repetitive ID code, based on comments from niels provos.

- seed2 is necessary, but use it as "seed2 + x" not "seed2 ^ x".
- skipping number is not needed, so disable it for 16bit generator (makes
  the repetition period to 30000)

1 files changed, 16 insertions, 12 deletions

diff --git a/src/lib/libc/net/res_random.c b/src/lib/libc/net/res_random.c
index c739e4a952..82d81e038a 100644
--- a/src/lib/libc/net/res_random.c
+++ b/src/lib/libc/net/res_random.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: res_random.c,v 1.12 2002/06/27 10:14:02 itojun Exp $ */
+/* $OpenBSD: res_random.c,v 1.13 2003/12/10 07:21:01 itojun Exp $ */
 
 /*
  * Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
@@ -111,9 +111,9 @@ pmod(u_int16_t gen, u_int16_t exp, u_int16_t mod)
 
         while (u) {
                 if (u & 1)
-                        s = (s*t) % mod;
+                        s = (s * t) % mod;
                 u >>= 1;
-                t = (t*t) % mod;
+                t = (t * t) % mod;
         }
         return (s);
 }
@@ -146,7 +146,7 @@ res_initid()
         ru_b = (tmp & 0xfffe) | 1;
         ru_a = pmod(RU_AGEN, (tmp >> 16) & 0xfffe, RU_M);
         while (ru_b % 3 == 0)
-          ru_b += 2;
+                ru_b += 2;
         
         tmp = arc4random();
         j = tmp % RU_N;
@@ -159,17 +159,17 @@ res_initid()
          */
 
         while (noprime) {
-                for (i=0; i<PFAC_N; i++)
-                        if (j%pfacts[i] == 0)
+                for (i = 0; i < PFAC_N; i++)
+                        if (j % pfacts[i] == 0)
                                 break;
 
-                if (i>=PFAC_N)
+                if (i >= PFAC_N)
                         noprime = 0;
                 else 
-                        j = (j+1) % RU_N;
+                        j = (j + 1) % RU_N;
         }
 
-        ru_g = pmod(RU_GEN,j,RU_N);
+        ru_g = pmod(RU_GEN, j, RU_N);
         ru_counter = 0;
 
         gettimeofday(&tv, NULL);
@@ -189,18 +189,22 @@ res_randomid()
         if (!tmp)
                 tmp = arc4random();
 
+#if 0
         /* Skip a random number of ids */
         n = tmp & 0x7; tmp = tmp >> 3;
         if (ru_counter + n >= RU_MAX)
                 res_initid();
+#else
+        n = 0;
+#endif
 
-        for (i=0; i<=n; i++)
+        for (i = 0; i <= n; i++)
                 /* Linear Congruential Generator */
-                ru_x = (ru_a*ru_x + ru_b) % RU_M;
+                ru_x = (ru_a * ru_x + ru_b) % RU_M;
 
         ru_counter += i;
 
-        return (ru_seed ^ pmod(ru_g,ru_seed2 ^ ru_x,RU_N)) | ru_msb;
+        return (ru_seed ^ pmod(ru_g, ru_seed2 + ru_x, RU_N)) | ru_msb;
 }
 
 #if 0