From 483e783649b0cb8341803ced63c0f72acb4a35db Mon Sep 17 00:00:00 2001
From: kcwu <kcwu@63ad8ddf-47c3-0310-b6dd-a9e9d9715204>
Date: Wed, 5 Oct 2005 19:35:25 +0000
Subject: make the ticket number less preditable.

git-svn-id: http://opensvn.csie.org/pttbbs/trunk/pttbbs@3220 63ad8ddf-47c3-0310-b6dd-a9e9d9715204
---
 util/openticket.c | 65 ++++++-------------------------------------------------
 1 file changed, 7 insertions(+), 58 deletions(-)

(limited to 'util')

diff --git a/util/openticket.c b/util/openticket.c
index f24aaea3..c200510d 100644
--- a/util/openticket.c
+++ b/util/openticket.c
@@ -56,64 +56,13 @@ int main(int argc, char **argv)
 	fclose(fp);
     }
 
-  srandom(33); //   固定一個  seed 但盡量要避免跟別人的seed同
- 
-  for( n = (now / (60*60*3)) - 62820; n >0; n--) random();
- 
-
-/* 
- * 正確的random number generator的用法
- * 是用同一個 seed後取 第一個 第二個 地三個.... 數
- * srand() 設完seed後
- * 每呼叫一次rand()就取下一個數
- *
- * 但因為我們沒有記錄上次取到第幾個
- * 所以用每增四小時()就多取一次 => now / (60*60*4) (每五小時開一次獎)
- * (減 61820 是減少 loop 數)
- *
- * 本來是用srand(time(0))  不是正確的用法
- * 因為開獎時間有規率 所以會被找出規律
- *
- *                                     ~Ptt
- */
-
- bet=random() % 8;
- /* 以上的說法及 code 並沒比 srand(time(0)) 好. 甚至更好預測. */
- 
-
- //XXX: resolve_utmp();
- attach_SHM();
-    bet = SHM->UTMPnumber % 8;
-  /* FIXME 現在完全依 UTMPnumber 取值, 並沒用到 random function.
-   * 小站的 UTMPnumber 可視為定值... */
-
-/*
-
- *
- * 若要以rand inplement 整數的亂數 要注意以下 (man page中有)
- *
- *     In Numerical Recipes in C: The Art of Scientific Computing
- *     (William  H.  Press, Brian P. Flannery, Saul A. Teukolsky,
- *     William T.  Vetterling;  New  York:  Cambridge  University
- *     Press,  1990 (1st ed, p. 207)), the following comments are
- *     made:
- *            "If you want to generate a random integer between 1
- *            and 10, you should always do it by
- *
- *                   j=1+(int) (10.0*rand()/(RAND_MAX+1.0));
- *
- *            and never by anything resembling
- *
- *                   j=1+((int) (1000000.0*rand()) % 10);
- *
- *            (which uses lower-order bits)."
- *
- *     Random-number  generation is a complex topic.  The Numeri-
- *     cal Recipes in C book (see reference  above)  provides  an
- *     excellent discussion of practical random-number generation
- *     issues in Chapter 7 (Random Numbers).
- *                                                     ~ Ptt
- */
+    /* 現在開獎號碼並沒用到 random function.
+     * 小站的 UTMPnumber 可視為定值, 且 UTMPnumber 預設一秒才更新一次
+     * 開站一段時間的開獎 pid 應該無法預測.
+     * 若是小站當站開獎前開站, 則有被猜中的可能 */
+    attach_SHM();
+    bet = (SHM->UTMPnumber+getpid()) % 8;
+
 
 
     money = ticket[bet] ? total * 95 / ticket[bet] : 9999999;
-- 
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