From: NHOrus <jy6x2b32pie9@yahoo.com>
Date: Thu, 24 Aug 2017 11:48:02 +0000 (+0300)
Subject: Prevent tampering with PRNG parameters in save
X-Git-Tag: 1.5~23
X-Git-Url: https://jxself.org/git/?a=commitdiff_plain;h=e5a0c6e2b723186e452747bccef5f3386ce2f2f9;p=open-adventure.git

Prevent tampering with PRNG parameters in save
---

diff --git a/main.c b/main.c
index 0f245a2..0556c01 100644
--- a/main.c
+++ b/main.c
@@ -1175,9 +1175,6 @@ Lookup:
         default: // LCOV_EXCL_LINE
             BUG(VOCABULARY_TYPE_N_OVER_1000_NOT_BETWEEN_0_AND_3); // LCOV_EXCL_LINE
         }
-        if (!is_valid(game)) {
-            exit(1);
-        }
         switch (action(command)) {
         case GO_TERMINATE:
             return true;
diff --git a/saveresume.c b/saveresume.c
index cf1dd6c..c5d5181 100644
--- a/saveresume.c
+++ b/saveresume.c
@@ -139,6 +139,12 @@ bool is_valid(struct game_t valgame)
         return false;
     }
 
+    /* Prevent RNG substitution. Why we are saving PRNG parameters? */
+
+    if (valgame.lcg_a != game.lcg_a || valgame.lcg_c != game.lcg_c || valgame.lcg_m != game.lcg_m) {
+        return false;
+    }
+
     /*  Bounds check for locations */
     if ( valgame.chloc < -1  || valgame.chloc > NLOCATIONS  ||
          valgame.chloc2 < -1  || valgame.chloc2 > NLOCATIONS  ||