0701 nwnss: make rand helpers seed deterministic

src/nwnss/library/misc/rand.c

@@ -4,12 +4,18 @@
  |
  |      The shipped NSS sources contain shared/sdk/library/rand.h and export
  |      these symbols from the NSS library import lists, but no corresponding
- |      C implementation was present in the supplied source archives.
+ |      C implementation was present in the supplied source archives or public
+ |      sources checked during the nwnss import audit.
  |
- |      Keep the NSS symbol surface and back every generated value with the
- |      bundled libsodium randombytes backend.  The seed entry points are kept
- |      as API-compatible state hooks only; they do not replace OS entropy with
- |      a private deterministic generator.
+ |      Novell LibC documents rand()/rand_r() as seeded pseudo-random sequence
+ |      APIs.  Keep the same seed-driven model for the wider NSS QUAD helpers:
+ |      srandQuad()/srndQuad()/srndLong() set deterministic state and subsequent
+ |      randQuad()/rndQuad()/rndLong() calls advance that state.  If callers use
+ |      the generator before explicitly seeding it, initialize the state once
+ |      from libsodium randombytes_buf(), which is the userspace equivalent of a
+ |      kernel random-byte source.
+ |
+ |      This is a MARS userspace port, not Novell original source.
  +-------------------------------------------------------------------------*/
 #include <rand.h>
 
@@ -18,12 +24,11 @@
 #include <sodium/core.h>
 #include <sodium/randombytes.h>
 
-static QUAD seedSalt;
-static QUAD seedCounter;
-static int haveSeedSalt;
+static QUAD randState;
+static int haveRandState;
 static int sodiumReady;
 
-static void nwnssRandInit(void)
+static void nwnssRandInitSodium(void)
 {
     if (!sodiumReady) {
         int rc = sodium_init();
@@ -32,34 +37,37 @@ static void nwnssRandInit(void)
     }
 }
 
-static QUAD nwnssSeedMix(void)
+static QUAD nwnssRandNextFromState(QUAD *state)
 {
     QUAD z;
 
-    if (!haveSeedSalt)
-        return 0;
-
-    z = seedSalt + (++seedCounter * 0x9e3779b97f4a7c15ULL);
+    *state += 0x9e3779b97f4a7c15ULL;
+    z = *state;
     z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9ULL;
     z = (z ^ (z >> 27)) * 0x94d049bb133111ebULL;
     return z ^ (z >> 31);
 }
 
+static void nwnssRandEnsureSeeded(void)
+{
+    if (haveRandState)
+        return;
+
+    nwnssRandInitSodium();
+    randombytes_buf(&randState, sizeof(randState));
+    haveRandState = 1;
+}
+
 void srandQuad(QUAD seed)
 {
-    seedSalt ^= seed + 0x4e53534c49424e57ULL;
-    seedCounter = 0;
-    haveSeedSalt = 1;
+    randState = seed;
+    haveRandState = 1;
 }
 
 SQUAD randQuad(void)
 {
-    QUAD value;
-
-    nwnssRandInit();
-    randombytes_buf(&value, sizeof(value));
-    value ^= nwnssSeedMix();
-    return (SQUAD)value;
+    nwnssRandEnsureSeeded();
+    return (SQUAD)nwnssRandNextFromState(&randState);
 }
 
 void srndQuad(QUAD seed)